Science.gov

Sample records for large a-fiber activity

  1. Active Q-switching of a fiber laser using a modulated fiber Fabry-Perot filter and a fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Martínez Manuel, Rodolfo; Kaboko, J. J. M.; Shlyagin, M. G.

    2016-02-01

    We propose and demonstrate a simple and robust actively Q-switched erbium-doped fiber ring cavity laser. The Q-switching is based on dynamic spectral overlapping of two filters, namely a fiber Bragg grating-based filter and a fiber Fabry-Perot tunable filter. Using 3.5 m of erbium-doped fiber and a pump power of only 60 mW, Q-switched pulses with a peak power of 9.7 W and a pulse duration of 500 ns were obtained. A pulse repetition rate can be continuously varied from a single shot to a few KHz.

  2. Sea-anemone toxin ATX-II elicits A-fiber-dependent pain and enhances resurgent and persistent sodium currents in large sensory neurons

    PubMed Central

    2012-01-01

    Background Gain-of-function mutations of the nociceptive voltage-gated sodium channel Nav1.7 lead to inherited pain syndromes, such as paroxysmal extreme pain disorder (PEPD). One characteristic of these mutations is slowed fast-inactivation kinetics, which may give rise to resurgent sodium currents. It is long known that toxins from Anemonia sulcata, such as ATX-II, slow fast inactivation and skin contact for example during diving leads to various symptoms such as pain and itch. Here, we investigated if ATX-II induces resurgent currents in sensory neurons of the dorsal root ganglion (DRGs) and how this may translate into human sensations. Results In large A-fiber related DRGs ATX-II (5 nM) enhances persistent and resurgent sodium currents, but failed to do so in small C-fiber linked DRGs when investigated using the whole-cell patch-clamp technique. Resurgent currents are thought to depend on the presence of the sodium channel β4-subunit. Using RT-qPCR experiments, we show that small DRGs express significantly less β4 mRNA than large sensory neurons. With the β4-C-terminus peptide in the pipette solution, it was possible to evoke resurgent currents in small DRGs and in Nav1.7 or Nav1.6 expressing HEK293/N1E115 cells, which were enhanced by the presence of extracellular ATX-II. When injected into the skin of healthy volunteers, ATX-II induces painful and itch-like sensations which were abolished by mechanical nerve block. Increase in superficial blood flow of the skin, measured by Laser doppler imaging is limited to the injection site, so no axon reflex erythema as a correlate for C-fiber activation was detected. Conclusion ATX-II enhances persistent and resurgent sodium currents in large diameter DRGs, whereas small DRGs depend on the addition of β4-peptide to the pipette recording solution for ATX-II to affect resurgent currents. Mechanical A-fiber blockade abolishes all ATX-II effects in human skin (e.g. painful and itch-like paraesthesias), suggesting that

  3. Observations of four types of pulses in a fiber laser with large net-normal dispersion.

    PubMed

    Wang, Leiran; Liu, Xueming; Gong, Yongkang; Mao, Dong; Duan, Lina

    2011-04-11

    Four different types of pulses are experimentally obtained in one erbium-doped all-fiber laser with large net-normal dispersion. The proposed laser can deliver the rectangular-spectrum (RS), Gaussian-spectrum (GS), broadband-spectrum (BS), and noise-like pulses by appropriately adjusting the polarization states. These kinds of pulses have distinctly different characteristics. The RS pulses can easily be compressed to femtosecond level whereas the pulse energy is restricted by the trend of multi-pulse shaping with excessive pump. The GS and BS pulses always maintain the single-pulse operation with much higher pulse-energy and accumulate much more chirp. After launching the pulses into the photonic-crystal fiber, the supercontinuum can be generated with the bandwidth of >700 nm by the BS pulses and of ~400 nm by the GS pulses, whereas it can hardly be generated by the RS pulses. The physical mechanisms behind the continuum generation are qualitatively investigated relating to different operating regimes. This work could help to a deeper insight of the normal-dispersion pulses.

  4. Pulse dynamics of dissipative soliton resonance with large duration-tuning range in a fiber ring laser.

    PubMed

    Luo, Zhi-Chao; Cao, Wen-Jun; Lin, Zhen-Bin; Cai, Ze-Rong; Luo, Ai-Ping; Xu, Wen-Cheng

    2012-11-15

    The pulse dynamics operating in dissipative soliton resonance (DSR) region is experimentally investigated in a fiber ring laser. With the increase of pump power, the pulse profile transit from sech-like to rectangular shape was observed. The generated pulse in DSR region exhibits the conventional soliton spectrum with sideband generation. The duration-tuning range of the rectangular pulse is up to the cavity roundtrip time. Particularly, during the process of pulse duration broadening it was found that the rectangular pulse would trap a weak pulse generated from cw background. The obtained results may be useful for better understanding the DSR phenomenon.

  5. Large-aperture CCD x-ray detector for protein crystallography using a fiber-optic taper

    NASA Astrophysics Data System (ADS)

    Strauss, Michael G.; Westbrook, Edwin M.; Naday, Istvan; Coleman, T. A.; Westbrook, Mary L.; Travis, D. J.; Sweet, Robert M.; Pflugrath, J. W.; Stanton, Martin J.

    1991-07-01

    A detector with a 114 mm aperture, based on a charge-coupled device (CCD), has been designed for x-ray diffraction studies in protein crystallography. The detector was tested on a beamline of the National Synchrotron Light Source at Brookhaven National Laboratory with a beam intensity greater than 10(superscript 9) x-ray photons/s. A fiber-optic taper, an image intensifier, and a lens demagnify, intensify, and focus the image onto a CCD having 512 X 512 pixels. A detective quantum efficiency (DQE) of 0.36 was obtained by evaluating the statistical uncertainty in the detector output. The dynamic range of a 4 X 4 pixel resolution element, comparable in size to a diffraction peak, was 10 (superscript 4). The point-spread function shows FWHM resolution of approximately 1 pixel, where a pixel on the detector face is 160 micrometers . A complete data set, consisting of forty-five 1 degree(s) rotation frames, was obtained in just 36 s of x-ray exposure to a crystal of chicken egg-white lysozyme. In a separate experiment, a lysozyme data set consisting of 495 0.1 degree(s) frames, was processed by the MADNES data reduction program, yielding symmetry R-factors for the data of 3.2- 3.5%. Diffraction images from crystals of the myosin S1 head (a equals 275 angstroms) were also recorded. The Bragg spots, only 5 pixels apart, were resolved but were not sufficiently separated to process these data. Changes in the detector design which will improve the DQE and spatial resolution are outlined. The overall performance showed that this type of detector is well suited for x-ray scattering investigations with synchrotron sources.

  6. The GMT-CFA-CARNEGIE-CATOLICA LARGE EARTH FINDER (G-CLEF): A Fiber-fed, Optical Echelle Spectrograph For The Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Szentgyorgyi, Andrew; Furesz, G.; Frebel, A.; Geary, J.; Evans, I.; Norton, T.; Hertz, E.; DePonte Evans, J.; Jordan, A.; Guzman, D.; Epps, H.; Barnes, S.; Crane, J.

    2011-01-01

    The GMT-CfA-Carnegie-Catolica Large Earth Finder (G-CLEF) is a fiber-fed optical echelle spectrograph in concept design study phase for first light at the Giant Magellan Telescope. G-CLEF is designed to be a multipurpose echelle spectrograph that operates in a number of modes so as to enable precision radial velocity (RV) measurements, detailed abundance studies, isotopic abundance measurements and probe the IGM and ISM at high Z. Four resolution modes are implemented with image and pupil slicing. Extremely precise RV will be achieved by vacuum enclosing the spectrograph, with advanced fiber scrambling and state-of-the-art calibrators, especially ultra stabilized etalons and possibly laser frequency combs. The optical design is a asymmetric white pupil design with two camera arms splitting the 350 nm - 950 nm passband into red and blue channels. G-CLEF will have an extremely large, mosaiced echelle grating and volume phase holograph cross dispersers.

  7. Active stabilization of a fiber-optic two-photon interferometer using continuous optical length control.

    PubMed

    Cho, Seok-Beom; Kim, Heonoh

    2016-05-16

    The practical realization of long-distance entanglement-based quantum communication systems strongly rely on the observation of highly stable quantum interference between correlated single photons. This task must accompany active stabilization of the optical path lengths within the single-photon coherence length. Here, we provide two-step interferometer stabilization methods employing continuous optical length control and experimentally demonstrate two-photon quantum interference using an actively stabilized 6-km-long fiber-optic Hong-Ou-Mandel interferometer. The two-step active control techniques are applied for measuring highly stable two-photon interference fringes by scanning the optical path-length difference. The obtained two-photon interference visibilities with and without accidental subtraction are found to be approximately 90.7% and 65.4%, respectively.

  8. Getting Active in the Large Lecture

    ERIC Educational Resources Information Center

    Huerta, Juan Carlos

    2007-01-01

    The benefits of active learning are well documented; nonetheless, the implementation of active learning strategies can be challenging in large lecture environments. The project will examine the research supporting active learning, present the implementation of simple active learning techniques in large lecture classes, and provide evidence to test…

  9. Patterns of seismic activity preceding large earthquakes

    NASA Technical Reports Server (NTRS)

    Shaw, Bruce E.; Carlson, J. M.; Langer, J. S.

    1992-01-01

    A mechanical model of seismic faults is employed to investigate the seismic activities that occur prior to major events. The block-and-spring model dynamically generates a statistical distribution of smaller slipping events that precede large events, and the results satisfy the Gutenberg-Richter law. The scaling behavior during a loading cycle suggests small but systematic variations in space and time with maximum activity acceleration near the future epicenter. Activity patterns inferred from data on seismicity in California demonstrate a regional aspect; increased activity in certain areas are found to precede major earthquake events. One example is given regarding the Loma Prieta earthquake of 1989 which is located near a fault section associated with increased activity levels.

  10. Patterns of seismic activity preceding large earthquakes

    NASA Technical Reports Server (NTRS)

    Shaw, Bruce E.; Carlson, J. M.; Langer, J. S.

    1992-01-01

    A mechanical model of seismic faults is employed to investigate the seismic activities that occur prior to major events. The block-and-spring model dynamically generates a statistical distribution of smaller slipping events that precede large events, and the results satisfy the Gutenberg-Richter law. The scaling behavior during a loading cycle suggests small but systematic variations in space and time with maximum activity acceleration near the future epicenter. Activity patterns inferred from data on seismicity in California demonstrate a regional aspect; increased activity in certain areas are found to precede major earthquake events. One example is given regarding the Loma Prieta earthquake of 1989 which is located near a fault section associated with increased activity levels.

  11. Large-scale physical activity data reveal worldwide activity inequality.

    PubMed

    Althoff, Tim; Sosič, Rok; Hicks, Jennifer L; King, Abby C; Delp, Scott L; Leskovec, Jure

    2017-07-20

    To be able to curb the global pandemic of physical inactivity and the associated 5.3 million deaths per year, we need to understand the basic principles that govern physical activity. However, there is a lack of large-scale measurements of physical activity patterns across free-living populations worldwide. Here we leverage the wide usage of smartphones with built-in accelerometry to measure physical activity at the global scale. We study a dataset consisting of 68 million days of physical activity for 717,527 people, giving us a window into activity in 111 countries across the globe. We find inequality in how activity is distributed within countries and that this inequality is a better predictor of obesity prevalence in the population than average activity volume. Reduced activity in females contributes to a large portion of the observed activity inequality. Aspects of the built environment, such as the walkability of a city, are associated with a smaller gender gap in activity and lower activity inequality. In more walkable cities, activity is greater throughout the day and throughout the week, across age, gender, and body mass index (BMI) groups, with the greatest increases in activity found for females. Our findings have implications for global public health policy and urban planning and highlight the role of activity inequality and the built environment in improving physical activity and health.

  12. Single and large grain activities at Fermilab

    SciTech Connect

    Antoine, Claire; /Fermilab

    2006-01-01

    This paper describes the ongoing activities at Fermilab for large grains and monocrystalline niobium. In addition to acquisition of local fabrication expertise, we plan to develop an R&D program dedicated to evidence the possible influence of crystal orientation on physical and chemical properties of niobium, such as mechanical properties, magnetic properties or surface contamination. Some considerations are also given about the morphology at grain boundaries and its role on the behavior of superconducting cavities.

  13. Large Active Retrodirective Arrays for Space Applications

    NASA Technical Reports Server (NTRS)

    Chernoff, R. C.

    1978-01-01

    An active retrodirective array (ARA) electronically points a microwave beam back at the apparent source of an incident pilot signal. Retrodirectivity is the result of phase conjugation of the pilot signal received by each element of the array. The problem of supplying the correct phase reference to the phase conjugation circuit (PCC) associated with each element of the array is solved by central phasing. By eliminating the need for structural rigidity, central phasing confers a decisive advantage on ARA's as large spaceborne antennas. A new form of central phasing suitable for very large arrays is described. ARA's may easily be modified to serve both as transmitting and receiving arrays simultaneously. Two new kinds of exact, frequency translating PCC's are described. Such PCC's provide the ARA with input-output isolation and freedom from squint. The pointing errors caused by the radial and transverse components of the ARA's velocity, by the propagation medium, and by multipath are discussed. A two element ARA breadboard was built and tested at JPL. Its performance is limited primarily by multipath induced errors.

  14. Active optics in Large Synoptic Survey Telescope

    NASA Astrophysics Data System (ADS)

    Liang, Ming; Krabbendam, Victor; Claver, Charles F.; Chandrasekharan, Srinivasan; Xin, Bo

    2012-09-01

    The Large Synoptic Survey Telescope (LSST) has a 3.5º field of view and F/1.2 focus that makes the performance quite sensitive to the perturbations of misalignments and mirror surface deformations. In order to maintain the image quality, LSST has an active optics system (AOS) to measure and correct those perturbations in a closed loop. The perturbed wavefront errors are measured by the wavefront sensors (WFS) located at the four corners of the focal plane. The perturbations are solved by the non-linear least square algorithm by minimizing the rms variation of the measured and baseline designed wavefront errors. Then the correction is realized by applying the inverse of the perturbations to the optical system. In this paper, we will describe the correction processing in the LSST AOS. We also will discuss the application of the algorithm, the properties of the sensitivity matrix and the stabilities of the correction. A simulation model, using ZEMAX as a ray tracing engine and MATLAB as an analysis platform, is set up to simulate the testing and correction loop of the LSST AOS. Several simulation examples and results are presented.

  15. Targeted chromosomal insertion of large DNA into the human genome by a fiber-modified high-capacity adenovirus-based vector system.

    PubMed

    Gonçalves, Manuel A F V; Holkers, Maarten; van Nierop, Gijsbert P; Wieringa, Roeland; Pau, Maria G; de Vries, Antoine A F

    2008-08-29

    A prominent goal in gene therapy research concerns the development of gene transfer vehicles that can integrate exogenous DNA at specific chromosomal loci to prevent insertional oncogenesis and provide for long-term transgene expression. Adenovirus (Ad) vectors arguably represent the most efficient delivery systems of episomal DNA into eukaryotic cell nuclei. The most advanced recombinant Ads lack all adenoviral genes. This renders these so-called high-capacity (hc) Ad vectors less cytotoxic/immunogenic than those only deleted in early regions and creates space for the insertion of large/multiple transgenes. The versatility of hcAd vectors is been increased by capsid modifications to alter their tropism and by the incorporation into their genomes of sequences promoting chromosomal insertion of exogenous DNA. Adeno-associated virus (AAV) can insert its genome into a specific human locus designated AAVS1. Trans- and cis-acting elements needed for this reaction are the AAV Rep78/68 proteins and Rep78/68-binding sequences, respectively. Here, we describe the generation, characterization and testing of fiber-modified dual hcAd/AAV hybrid vectors (dHVs) containing both these elements. Due to the inhibitory effects of Rep78/68 on Ad-dependent DNA replication, we deployed a recombinase-inducible gene switch to repress Rep68 synthesis during vector rescue and propagation. Flow cytometric analyses revealed that rep68-positive dHVs can be produced similarly well as rep68-negative control vectors. Western blot experiments and immunofluorescence microscopy analyses demonstrated transfer of recombinase-dependent rep68 genes into target cells. Studies in HeLa cells and in the dystrophin-deficient myoblasts from a Duchenne muscular dystrophy (DMD) patient showed that induction of Rep68 synthesis in cells transduced with fiber-modified and rep68-positive dHVs leads to increased stable transduction levels and AAVS1-targeted integration of vector DNA. These results warrant further

  16. Silent Students' Participation in a Large Active Learning Science Classroom

    ERIC Educational Resources Information Center

    Obenland, Carrie A.; Munson, Ashlyn H.; Hutchinson, John S.

    2012-01-01

    Active learning in large science classrooms furthers opportunities for students to engage in the content and in meaningful learning, yet students can still remain anonymously silent. This study aims to understand the impact of active learning on these silent students in a large General Chemistry course taught via Socratic questioning and…

  17. ACTIVE SOIL DEPRESSURIZATION (ASD) DEMONSTRATION IN A LARGE BUILDING

    EPA Science Inventory

    The report gives results of an evaluation of the feasibility of implementing radon resistant construction techniques -- especially active soil depressurization (ASD) -- in new large buildings in Florida. Indoor radon concentrations and radon entry were monitored in a finished bui...

  18. ACTIVE SOIL DEPRESSURIZATION (ASD) DEMONSTRATION IN A LARGE BUILDING

    EPA Science Inventory

    The report gives results of an evaluation of the feasibility of implementing radon resistant construction techniques -- especially active soil depressurization (ASD) -- in new large buildings in Florida. Indoor radon concentrations and radon entry were monitored in a finished bui...

  19. 105-DR Large Sodium Fire Facility closure activities evaluation report

    SciTech Connect

    Adler, J.G.

    1996-04-11

    This report evaluates the closure activities at the 105-DR Large Sodium Fire Facility. The evaluation compares these activities to the regulatory requirements and closure plan requirements. The report concludes that the areas identified in the closure plan can be clean closed. This report summarizes and evaluates the closure activities performed in support of partial closure of the 105-DR Large Sodium Fire Facility (LSFF). This evaluation will be used in assessing the condition of the 105-DR LSFF for the purpose of meeting the partial clean closure conditions described in the 105-DR Large Sodium Fire Facility Closure Plan (DOE-RL 1995). Based on the evaluation of the decontamination activities, sampling activities, and sample data, it is has been determined that the partial clean closure conditions for the 105-DR LSFF have been met.

  20. Engaging Students in Large Health Classes with Active Learning Strategies

    ERIC Educational Resources Information Center

    Elliott, Steven; Combs, Sue; Huelskamp, Amelia; Hritz, Nancy

    2017-01-01

    Creative K-12 health teachers can engage students in large classes by utilizing active learning strategies. Active learning involves engaging students in higher-order tasks, such as analysis and synthesis, which is a crucial element of the movement toward what is commonly called "learner-centered" teaching. Health education teachers who…

  1. Two Learning Activities for a Large Introductory Statistics Class

    ERIC Educational Resources Information Center

    Zacharopoulou, Hrissoula

    2006-01-01

    In a very large Introductory Statistics class, i.e. in a class of more than 300 students, instructors may hesitate to apply active learning techniques, discouraged by the volume of extra work. In this paper two such activities are presented that evoke student involvement in the learning process. The first is group peer teaching and the second is…

  2. Inhibition of mechanical allodynia in neuropathic pain by TLR5-mediated A-fiber blockade

    PubMed Central

    Xu, Zhen-Zhong; Kim, Yong Ho; Bang, Sangsu; Zhang, Yi; Berta, Temugin; Wang, Fan; Oh, Seog Bae; Ji, Ru-Rong

    2016-01-01

    SUMMARY Mechanical allodynia, induced by normally innocuous low-threshold mechanical stimulation, represents a cardinal feature of neuropathic pain. Blockade or ablation of high-threshold small-diameter unmyelinated C-fibers has limited effects on mechanical allodynia1–4. While large myelinated A-fibers, in particular Aβ-fibers, have previously been implicated in mechanical allodynia5–7, an A-fiber-selective pharmacological blocker is still lacking. Here we report a new method for targeted silencing of A-fibers in neuropathic pain. We found that Toll-like receptor 5 (TLR5) is co-expressed with neurofilament-200 in large-diameter A-fiber neurons in the dorsal root ganglion (DRG). Activation of TLR5 with its ligand flagellin results in neuronal entry of the membrane impermeable lidocaine derivative QX-314, leading to TLR5-dependent blockade of sodium currents predominantly in A-fiber neurons of mouse DRGs. Intraplantar co-application of flagellin and QX-314 (flagellin/QX-314) dose-dependently suppressed mechanical allodynia following chemotherapy, nerve injury, and diabetic neuropathy, but this blockade is abrogated in Tlr5-deficient mice. In vivo electrophysiology demonstrated that flagellin/QX-314 co-application selectively suppressed Aβ-fiber conduction in naive and chemotherapy-treated mice. TLR5-mediated Aβ blockade but not capsaicin-mediated C-fiber blockade also reduced chemotherapy-induced ongoing pain without impairing motor function. Finally, flagellin/QX-314 co-application suppressed sodium currents in large-diameter human DRG neurons. Thus, our findings provide a new tool for targeted silencing of Aβ-fibers and neuropathic pain treatment. PMID:26479925

  3. Distributed active control of large flexible space structures

    NASA Technical Reports Server (NTRS)

    Nguyen, C. C.; Baz, A.

    1986-01-01

    This progress report summarizes the research work performed at the Catholic University of America on the research grant entitled Distributed Active Control of Large Flexible Space Structures, funded by NASA/Goddard Space Flight Center, under grant number NAG5-749, during the period of March 15, 1986 to September 15, 1986.

  4. Development and testing of an actively controlled large-aperture Cassegrain Telescope for spacecraft deployment

    NASA Astrophysics Data System (ADS)

    Boone, Bradley G.; Bruzzi, Jonathan R.; Kluga, Bernard E.; Rogala, Eric W.; Hale, R. D.; Chen, Peter C.

    2004-10-01

    The National Aeronautics and Space Administration (NASA) is planning future deep space missions requiring space-based imaging reconnaissance of planets and recovery of imagery from these missions via optical communications. Both applications have similar requirements that can be met by a common aperture. The Johns Hopkins University Applied Physics Laboratory in collaboration with commercial and academic partners is developing a new approach to deploying and controlling large aperture (meter-class) optical telescopes on spacecraft that can be rapidly launched and deployed. The deployment mechanism uses flexible longeron struts to deploy the secondary. The active control system uses a fiber-coupled laser array near the focal plane that reflects four collimated laser beams off of the periphery of the secondary to four equally-disposed quad cell sensors at the periphery of the primary to correct secondary-to-primary misalignments and enable motion compensation. We describe a compensation technique that uses tip/tilt and piston actuators for quasi-static bias correction and dynamic motion compensation. We also describe preliminary optical tests using a commercial Schmidt-Cassegrain telescope in lieu of an ultra-lightweight composite Cassegrain, which is under development by Composite Mirror Applications, Inc. Finite element and ray trace modeling results for a 40 cm composite telescope design will also be described.

  5. Thermal activation of dislocations in large scale obstacle bypass

    NASA Astrophysics Data System (ADS)

    Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

    2017-08-01

    Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

  6. Large-scale multielectrode recording and stimulation of neural activity

    NASA Astrophysics Data System (ADS)

    Sher, A.; Chichilnisky, E. J.; Dabrowski, W.; Grillo, A. A.; Grivich, M.; Gunning, D.; Hottowy, P.; Kachiguine, S.; Litke, A. M.; Mathieson, K.; Petrusca, D.

    2007-09-01

    Large circuits of neurons are employed by the brain to encode and process information. How this encoding and processing is carried out is one of the central questions in neuroscience. Since individual neurons communicate with each other through electrical signals (action potentials), the recording of neural activity with arrays of extracellular electrodes is uniquely suited for the investigation of this question. Such recordings provide the combination of the best spatial (individual neurons) and temporal (individual action-potentials) resolutions compared to other large-scale imaging methods. Electrical stimulation of neural activity in turn has two very important applications: it enhances our understanding of neural circuits by allowing active interactions with them, and it is a basis for a large variety of neural prosthetic devices. Until recently, the state-of-the-art in neural activity recording systems consisted of several dozen electrodes with inter-electrode spacing ranging from tens to hundreds of microns. Using silicon microstrip detector expertise acquired in the field of high-energy physics, we created a unique neural activity readout and stimulation framework that consists of high-density electrode arrays, multi-channel custom-designed integrated circuits, a data acquisition system, and data-processing software. Using this framework we developed a number of neural readout and stimulation systems: (1) a 512-electrode system for recording the simultaneous activity of as many as hundreds of neurons, (2) a 61-electrode system for electrical stimulation and readout of neural activity in retinas and brain-tissue slices, and (3) a system with telemetry capabilities for recording neural activity in the intact brain of awake, naturally behaving animals. We will report on these systems, their various applications to the field of neurobiology, and novel scientific results obtained with some of them. We will also outline future directions.

  7. Large Roads Reduce Bat Activity across Multiple Species

    PubMed Central

    Kitzes, Justin; Merenlender, Adina

    2014-01-01

    Although the negative impacts of roads on many terrestrial vertebrate and bird populations are well documented, there have been few studies of the road ecology of bats. To examine the effects of large roads on bat populations, we used acoustic recorders to survey bat activity along ten 300 m transects bordering three large highways in northern California, applying a newly developed statistical classifier to identify recorded calls to the species level. Nightly counts of bat passes were analyzed with generalized linear mixed models to determine the relationship between bat activity and distance from a road. Total bat activity recorded at points adjacent to roads was found to be approximately one-half the level observed at 300 m. Statistically significant road effects were also found for the Brazilian free-tailed bat (Tadarida brasiliensis), big brown bat (Eptesicus fuscus), hoary bat (Lasiurus cinereus), and silver-haired bat (Lasionycteris noctivagans). The road effect was found to be temperature dependent, with hot days both increasing total activity at night and reducing the difference between activity levels near and far from roads. These results suggest that the environmental impacts of road construction may include degradation of bat habitat and that mitigation activities for this habitat loss may be necessary to protect bat populations. PMID:24823689

  8. Large roads reduce bat activity across multiple species.

    PubMed

    Kitzes, Justin; Merenlender, Adina

    2014-01-01

    Although the negative impacts of roads on many terrestrial vertebrate and bird populations are well documented, there have been few studies of the road ecology of bats. To examine the effects of large roads on bat populations, we used acoustic recorders to survey bat activity along ten 300 m transects bordering three large highways in northern California, applying a newly developed statistical classifier to identify recorded calls to the species level. Nightly counts of bat passes were analyzed with generalized linear mixed models to determine the relationship between bat activity and distance from a road. Total bat activity recorded at points adjacent to roads was found to be approximately one-half the level observed at 300 m. Statistically significant road effects were also found for the Brazilian free-tailed bat (Tadarida brasiliensis), big brown bat (Eptesicus fuscus), hoary bat (Lasiurus cinereus), and silver-haired bat (Lasionycteris noctivagans). The road effect was found to be temperature dependent, with hot days both increasing total activity at night and reducing the difference between activity levels near and far from roads. These results suggest that the environmental impacts of road construction may include degradation of bat habitat and that mitigation activities for this habitat loss may be necessary to protect bat populations.

  9. Fluid Coating on a Fiber

    NASA Astrophysics Data System (ADS)

    Quéré, David

    1999-01-01

    We discuss the thickness of the liquid layer entrained by a solid drawn out of a bath, focusing on the case where the solid is a fiber or a wire. Slow withdrawals out of a pure or a complex fluid are described as well as quick coatings. We specify the general laws of entrainment and stress the cases where the fiber curvature plays a role. We finally give an overview on the further evolution of the coated film.

  10. Expression and purification of large active GST fusion enzymes.

    PubMed

    Deceglie, Stefania; Lionetti, Claudia; Roberti, Marina; Cantatore, Palmiro; Polosa, Paola Loguercio

    2014-01-01

    GST fusion proteins expressed in bacteria often tend to form aggregates and are inefficiently purified by standard procedures, which employ a mixture of detergents that compromise the binding efficiency to the affinity resin and the biological activity of the recombinant proteins. Moreover, the binding to the resin is negatively affected by the molecular weight of the fusion protein. Here we report a simple and efficient method to purify active large GST-tagged proteins, which uses high ionic strength buffer to solubilize the protein aggregates in a bacterial lysate. Affinity-chromatography purification is achieved by adopting two columns connected in series, which facilitate the binding of large GST fused molecules. This approach was applied to purify the 180-kDa GST-tagged mitochondrial RNA polymerase. We also report conditions for simple and efficient GST tag removal from the eluted protein. Finally we demonstrate that the recombinant enzyme is capable to catalyze RNA synthesis.

  11. Active Learning in a Large General Physics Classroom.

    NASA Astrophysics Data System (ADS)

    Trousil, Rebecca

    2008-04-01

    In 2004, we launched a new calculus-based, introductory physics sequence at Washington University. Designed as an alternative to our traditional lecture-based sequence, the primary objectives for this new course were to actively engage students in the learning process, to significantly strengthen students' conceptual reasoning skills, to help students develop higher level quantitative problem solving skills necessary for analyzing ``real world'' problems, and to integrate modern physics into the curriculum. This talk will describe our approach, using The Six Ideas That Shaped Physics text by Thomas Moore, to creating an active learning environment in large classes as well as share our perspective on key elements for success and challenges that we face in the large class environment.

  12. The LATT way towards large active primaries for space telescopes

    NASA Astrophysics Data System (ADS)

    Briguglio, Runa; Arcidiacono, Carmelo; Xompero, Marco; Lisi, Franco; Riccardi, Armando; Biasi, Roberto; Patauner, Christian; Gallieni, Daniele; Lazzarini, Paolo; Tintori, Matteo; d'Amato, Francesco; Pucci, Mauro; Duò, Fabrizio; Vettore, Christian; Zuccaro Marchi, Alessandro

    2016-07-01

    The Large Aperture Telescope Technology (LATT) goes beyond the current paradigm of future space telescopes, based on a deformable mirror in the pupil relay. Through the LATT project we demonstrated the concept of a low-weight active primary mirror, whose working principle and control strategy benefit from two decades of advances in adaptive optics for ground-based telescopes. We developed a forty centimeter spherical mirror prototype, with an areal density lower than 17 kg/m2, controlled through contactless voice coil actuators with co-located capacitive position sensors. The prototype was subjected to thermo-vacuum, vibration and optical tests, to push its technical readiness toward level 5. In this paper we present the background and the outcomes of the LATT activities under ESA contract (TRP programme), exploring the concept of a lightweight active primary mirror for space telescopes. Active primaries will open the way to very large segmented apertures, actively shaped, which can be lightweight, deployable and accurately phased once in flight.

  13. Biofidelic Human Activity Modeling and Simulation with Large Variability

    DTIC Science & Technology

    2014-11-25

    AFRL- RH -WP-TR-2014-0137 BIOFIDELIC HUMAN ACTIVITY MODELING AND SIMULATION WITH LARGE VARIABILITY John Camp Darrell Lochtefeld...obtained from the Defense Technical Information Center (DTIC) (http://www.dtic.mil). AFRL- RH -WP-TR-2014-0137 HAS BEEN REVIEWED AND IS APPROVED FOR...Branch Wright-Patterson Air Force Base, OH 45433   11. SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL- RH -WP-TR-2014-0137 12. DISTRIBUTION

  14. Cheap and near exact CASSCF with large active spaces.

    PubMed

    Smith, James E T; Mussard, Bastien; Holmes, Adam A; Sharma, Sandeep

    2017-10-02

    We use the recently-developed Heat-bath Configuration Interaction (HCI) algorithm as an efficient active-space solver to perform multi-configuration self-consistent field calculations (HCISCF) with large active spaces. We give a detailed derivation of the theory and show that difficulties associated with non-variationality of the HCI procedure can be overcome by making use of the Lagrangian formulation to calculate the HCI relaxed two body reduced density matrix. HCISCF is then used to study the electronic structure of butadiene, pentacene, and Fe-porphyrin. One of the most striking results of our work is that the converged active space orbitals obtained from HCISCF are relatively insensitive to the accuracy of the HCI calculation. This allows us to obtain nearly converged CASSCF energies with an estimated error of less than 1 mHa using the orbitals obtained from the HCISCF procedure in which the integral transformation is the dominant cost. For example, an HCISCF calculation on Fe-Porphyrin model complex with an active space of (44e, 44o) took only 412 seconds per iteration on a single node containing 28 cores, out of which 185 seconds were spent in the HCI calculation and the remaining 227 seconds were mainly used for integral transformation. Finally, we also show that active-space orbitals can be optimized using HCISCF to substantially speed up the convergence of the HCI energy to the Full CI limit because HCI is not invariant to unitary transformations within the active space.

  15. Large area flexible SERS active substrates using engineered nanostructures

    NASA Astrophysics Data System (ADS)

    Chung, Aram J.; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as

  16. Technologies for imaging neural activity in large volumes

    PubMed Central

    Ji, Na; Freeman, Jeremy; Smith, Spencer L.

    2017-01-01

    Neural circuitry has evolved to form distributed networks that act dynamically across large volumes. Collecting data from individual planes, conventional microscopy cannot sample circuitry across large volumes at the temporal resolution relevant to neural circuit function and behaviors. Here, we review emerging technologies for rapid volume imaging of neural circuitry. We focus on two critical challenges: the inertia of optical systems, which limits image speed, and aberrations, which restrict the image volume. Optical sampling time must be long enough to ensure high-fidelity measurements, but optimized sampling strategies and point spread function engineering can facilitate rapid volume imaging of neural activity within this constraint. We also discuss new computational strategies for the processing and analysis of volume imaging data of increasing size and complexity. Together, optical and computational advances are providing a broader view of neural circuit dynamics, and help elucidate how brain regions work in concert to support behavior. PMID:27571194

  17. Oxidative Regulation of Large Conductance Calcium-Activated Potassium Channels

    PubMed Central

    Tang, Xiang D.; Daggett, Heather; Hanner, Markus; Garcia, Maria L.; McManus, Owen B.; Brot, Nathan; Weissbach, Herbert; Heinemann, Stefan H.; Hoshi, Toshinori

    2001-01-01

    Reactive oxygen/nitrogen species are readily generated in vivo, playing roles in many physiological and pathological conditions, such as Alzheimer's disease and Parkinson's disease, by oxidatively modifying various proteins. Previous studies indicate that large conductance Ca2+-activated K+ channels (BKCa or Slo) are subject to redox regulation. However, conflicting results exist whether oxidation increases or decreases the channel activity. We used chloramine-T, which preferentially oxidizes methionine, to examine the functional consequences of methionine oxidation in the cloned human Slo (hSlo) channel expressed in mammalian cells. In the virtual absence of Ca2+, the oxidant shifted the steady-state macroscopic conductance to a more negative direction and slowed deactivation. The results obtained suggest that oxidation enhances specific voltage-dependent opening transitions and slows the rate-limiting closing transition. Enhancement of the hSlo activity was partially reversed by the enzyme peptide methionine sulfoxide reductase, suggesting that the upregulation is mediated by methionine oxidation. In contrast, hydrogen peroxide and cysteine-specific reagents, DTNB, MTSEA, and PCMB, decreased the channel activity. Chloramine-T was much less effective when concurrently applied with the K+ channel blocker TEA, which is consistent with the possibility that the target methionine lies within the channel pore. Regulation of the Slo channel by methionine oxidation may represent an important link between cellular electrical excitability and metabolism. PMID:11222629

  18. Large area flexible SERS active substrates using engineered nanostructures.

    PubMed

    Chung, Aram J; Huh, Yun Suk; Erickson, David

    2011-07-01

    Surface enhanced Raman scattering (SERS) is an analytical sensing method that provides label-free detection, molecularly specific information, and extremely high sensitivity. The Raman enhancement that makes this method attractive is mainly attributed to the local amplification of the incident electromagnetic field that occurs when a surface plasmon mode is excited at a metallic nanostructure. Here, we present a simple, cost effective method for creating flexible, large area SERS-active substrates using a new technique we call shadow mask assisted evaporation (SMAE). The advantage of large, flexible SERS substrates such as these is they have more area for multiplexing and can be incorporated into irregular surfaces such as clothing. We demonstrate the formation of four different types of nanostructure arrays (pillar, nib, ellipsoidal cylinder, and triangular tip) by controlling the evaporation angle, substrate rotation, and deposition rate of metals onto anodized alumina nanoporous membranes as large as 27 mm. In addition, we present experimental results showing how a hybrid structure comprising of gold nanospheres embedded in a silver nano-pillar structure can be used to obtain a 50× SERS enhancement over the raw nanoparticles themselves.

  19. Regional Triggering of Volcanic Activity Following Large Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Hill-Butler, Charley; Blackett, Matthew; Wright, Robert

    2015-04-01

    There are numerous reports of a spatial and temporal link between volcanic activity and high magnitude seismic events. In fact, since 1950, all large magnitude earthquakes have been followed by volcanic eruptions in the following year - 1952 Kamchatka M9.2, 1960 Chile M9.5, 1964 Alaska M9.2, 2004 & 2005 Sumatra-Andaman M9.3 & M8.7 and 2011 Japan M9.0. While at a global scale, 56% of all large earthquakes (M≥8.0) in the 21st century were followed by increases in thermal activity. The most significant change in volcanic activity occurred between December 2004 and April 2005 following the M9.1 December 2004 earthquake after which new eruptions were detected at 10 volcanoes and global volcanic flux doubled over 52 days (Hill-Butler et al. 2014). The ability to determine a volcano's activity or 'response', however, has resulted in a number of disparities with <50% of all volcanoes being monitored by ground-based instruments. The advent of satellite remote sensing for volcanology has, therefore, provided researchers with an opportunity to quantify the timing, magnitude and character of volcanic events. Using data acquired from the MODVOLC algorithm, this research examines a globally comparable database of satellite-derived radiant flux alongside USGS NEIC data to identify changes in volcanic activity following an earthquake, February 2000 - December 2012. Using an estimate of background temperature obtained from the MODIS Land Surface Temperature (LST) product (Wright et al. 2014), thermal radiance was converted to radiant flux following the method of Kaufman et al. (1998). The resulting heat flux inventory was then compared to all seismic events (M≥6.0) within 1000 km of each volcano to evaluate if changes in volcanic heat flux correlate with regional earthquakes. This presentation will first identify relationships at the temporal and spatial scale, more complex relationships obtained by machine learning algorithms will then be examined to establish favourable

  20. Drop impact on a fiber

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Gil; Kim, Wonjung

    2016-04-01

    We present the results of a combined experimental and theoretical investigation of drop impact on a thin fiber. Using high-speed videography, we analyze the dynamics of droplet collision with a fiber. Based on the systematic experiments, we identify three outcomes of collision: capturing, single drop falling, and splitting. The outcomes are presented in a regime map, where the regime boundaries are explained through a scale analysis of forces. We also measure the liquid retention on the fiber after the droplet impact. By considering a liquid film on the fiber, we develop a mechanical model that predicts the residual water mass. Our model reveals that the residual mass depends critically on the fiber thickness and less on the impact speed. Our study can be extended to predicting the remaining droplet, critical problems in air filtration, water collection, and fiber coating.

  1. Active disturbance rejection in large flexible space structures

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Sunkel, John W.

    1990-01-01

    The design of an active control law for the rejection of persistent disturbances, in large space structures is presented. The control system design approach is based on a deterministic model of the disturbances and it optimizes the magnitude of the disturbance that the structure can tolerate without violating certain predetermined constraints. In addition to closed-loop stability, the explicit treatment of state, control, and control rate constraints, such as structural displacement and control actuator effort, guarantees that the final design will exhibit desired performance characteristics. The technique is applied to a simple two-bay truss structure, and its response is compared with that obtained using a linear-quadratic-Gaussian/loop-transfer-recovery (LQG/LTR) compensator. Preliminary results indicate that the proposed control system can reject persistent disturbances of greater magnitude by utilizing most of the available control, while limiting the structural displacements to within desired tolerances.

  2. Progress in the active development of large optics for astronomy

    NASA Astrophysics Data System (ADS)

    Rees, David Jon

    An international consortium consisting of the United States, United Kingdom, Canada, Brazil, Chile and Argentina are planning to revolutionize the field of astronomy by building the two GEMINI 8m astronomical telescopes. These are designed to provide unprecedented image quality, which should significantly increase our knowledge and understanding of the structure and dynamics of the universe. To provide such superb image quality, the specifications of almost every aspect of the telescope are tighter than for any other ever built. The work described in this thesis is part of the ongoing research currently being undertaken in the Optical Science Laboratory into the production of large, highly aspheric optical surfaces. Meeting the design specifications for the GEMINI secondary mirrors is believed to be impossible using conventional craft techniques, but it is expected to be a tractable problem when utilizing the Active Lap technique described herein. The goal of the project is to demonstrate this technique by producing a 1/3 scale model of these mirrors. Broadly speaking, the Active Lap uses closed loop control of a system comprising of arrays of load cells and force actuators to control the ablation of the mirror in real time. This is a significant step forward in the field, and aims to propel conventional craft techniques which date back to the time of Sir Isaac Newton into the 21st century! A major contribution of the author to the Active Lap research project was the data acquisition and control software, which was designed to be ergonomic and make efficient use of cpu time. Other significant contributions involved calibration methods, system testing, and development of the closed loop control algorithms. In particular the novel idea of utilizing artificial neural networks to replace these algorithms is discussed. Finally, the performance of the Active Lap is evaluated, and suggestions are made for both the strategy for its future use, and the investigations

  3. Structural and functional maturation of active zones in large synapses.

    PubMed

    Cano, Raquel; Torres-Benito, Laura; Tejero, Rocío; Biea, Anca I; Ruiz, Rocío; Betz, William J; Tabares, Lucía

    2013-02-01

    Virtually all functions of the nervous system rely upon synapses, the sites of communication between neurons and between neurons and other cells. Synapses are complex structures, each one comprising hundreds of different types of molecules working in concert. They are organized by adhesive and scaffolding molecules that align presynaptic vesicular release sites, namely, active zones, with postsynaptic neurotransmitter receptors, thereby allowing rapid and reliable intercellular communication. Most synapses are relatively small, and acting alone exerts little effect on their postsynaptic partners. Some, however, are much larger and stronger, reliably driving the postsynaptic cell to its action potential threshold, acting essentially as electrical relays of excitation. These large synapses are among the best understood, and two of these are the subject of this review, namely, the vertebrate neuromuscular junction and the calyx of Held synapse in the mammalian auditory pathway of the brain stem. Both synapses undergo through a complex and well-coordinated maturation process, during which time the molecular elements and the biophysical properties of the secretory machinery are continuously adjusted to the synapse size and to the functional requirements. We here review the morphological and functional changes occurring during postnatal maturation, noting particular similarities and differences between these two large synapses.

  4. Active Removal of Large Debris: Electrical Propulsion Capabilities

    NASA Astrophysics Data System (ADS)

    Billot Soccodato, Carole; Lorand, Anthony; Perrin, Veronique; Couzin, Patrice; FontdecabaBaig, Jordi

    2013-08-01

    The risk for current operational spacecraft or future market induced by large space debris, dead satellites or rocket bodies, in Low Earth Orbit has been identified several years ago. Many potential solutions and architectures are traded with a main objective of reducing cost per debris. Based on cost consideration, specially driven by launch cost, solutions constructed on multi debris capture capacities seem to be much affordable The recent technologic evolutions in electric propulsion and solar power generation can be used to combine high potential vehicles for debris removal. The present paper reports the first results of a study funded by CNES that addresses full electric solutions for large debris removal. Some analysis are currently in progress as the study will end in August. It compares the efficiency of in-orbit Active Removal of typical debris using electric propulsion The electric engine performances used in this analysis are demonstrated through a 2012/2013 PPS 5000 on-ground tests campaign. The traded missions are based on a launch in LEO, the possible vehicle architectures with capture means or contact less, the selection of deorbiting or reorbiting strategy. For contact less strategy, the ion-beam shepherd effect towards the debris problematic will be addressed. Vehicle architecture and performance of the overall system will be stated, showing the adequacy and the limits of each solution.

  5. Large-Aperture Membrane Active Phased-Array Antennas

    NASA Technical Reports Server (NTRS)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  6. Imaging Large Cohorts of Single Ion Channels and Their Activity

    PubMed Central

    Hiersemenzel, Katia; Brown, Euan R.; Duncan, Rory R.

    2013-01-01

    As calcium is the most important signaling molecule in neurons and secretory cells, amongst many other cell types, it follows that an understanding of calcium channels and their regulation of exocytosis is of vital importance. Calcium imaging using calcium dyes such as Fluo3, or FRET-based dyes that have been used widely has provided invaluable information, which combined with modeling has estimated the subtypes of channels responsible for triggering the exocytotic machinery as well as inferences about the relative distances away from vesicle fusion sites these molecules adopt. Importantly, new super-resolution microscopy techniques, combined with novel Ca2+ indicators and imaginative imaging approaches can now define directly the nano-scale locations of very large cohorts of single channel molecules in relation to single vesicles. With combinations of these techniques the activity of individual channels can be visualized and quantified using novel Ca2+ indicators. Fluorescently labeled specific channel toxins can also be used to localize endogenous assembled channel tetramers. Fluorescence lifetime imaging microscopy and other single-photon-resolution spectroscopic approaches offer the possibility to quantify protein–protein interactions between populations of channels and the SNARE protein machinery for the first time. Together with simultaneous electrophysiology, this battery of quantitative imaging techniques has the potential to provide unprecedented detail describing the locations, dynamic behaviors, interactions, and conductance activities of many thousands of channel molecules and vesicles in living cells. PMID:24027557

  7. Spatiotemporal dynamics of large-scale brain activity

    NASA Astrophysics Data System (ADS)

    Neuman, Jeremy

    Understanding the dynamics of large-scale brain activity is a tough challenge. One reason for this is the presence of an incredible amount of complexity arising from having roughly 100 billion neurons connected via 100 trillion synapses. Because of the extremely high number of degrees of freedom in the nervous system, the question of how the brain manages to properly function and remain stable, yet also be adaptable, must be posed. Neuroscientists have identified many ways the nervous system makes this possible, of which synaptic plasticity is possibly the most notable one. On the other hand, it is vital to understand how the nervous system also loses stability, resulting in neuropathological diseases such as epilepsy, a disease which affects 1% of the population. In the following work, we seek to answer some of these questions from two different perspectives. The first uses mean-field theory applied to neuronal populations, where the variables of interest are the percentages of active excitatory and inhibitory neurons in a network, to consider how the nervous system responds to external stimuli, self-organizes and generates epileptiform activity. The second method uses statistical field theory, in the framework of single neurons on a lattice, to study the concept of criticality, an idea borrowed from physics which posits that in some regime the brain operates in a collectively stable or marginally stable manner. This will be examined in two different neuronal networks with self-organized criticality serving as the overarching theme for the union of both perspectives. One of the biggest problems in neuroscience is the question of to what extent certain details are significant to the functioning of the brain. These details give rise to various spatiotemporal properties that at the smallest of scales explain the interaction of single neurons and synapses and at the largest of scales describe, for example, behaviors and sensations. In what follows, we will shed some

  8. Droplet impact on a fiber

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Gil; Kim, Taehong; Kim, Wonjung

    2015-11-01

    We present the results of a combined experimental and theoretical investigation of drop impact on a fiber. We use high-speed videography to characterize the dynamics of drops impacting fibers. Our systematical experiments reveal that the outcome of droplet collision critically depends on the relative magnitude of inertial to capillary forces and the ratio of the thickness of fiber to the diameter of the drop. We identify three outcomes of the collision using a non-dimensional regime map. The selection among the modes of single capturing, single drop falling, and divided drop falling is explained through a scale analysis of forces. We also examine the droplet retention on the fiber after impact. For each mode, we suggest the mathematical models to predict the amount of residual water on the fiber. Our study can be extended to predicting the remaining droplet, the critical problem in air filtration, water collection, and fiber coating. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (2009-0083510).

  9. Modelling large scale human activity in San Francisco

    NASA Astrophysics Data System (ADS)

    Gonzalez, Marta

    2010-03-01

    Diverse group of people with a wide variety of schedules, activities and travel needs compose our cities nowadays. This represents a big challenge for modeling travel behaviors in urban environments; those models are of crucial interest for a wide variety of applications such as traffic forecasting, spreading of viruses, or measuring human exposure to air pollutants. The traditional means to obtain knowledge about travel behavior is limited to surveys on travel journeys. The obtained information is based in questionnaires that are usually costly to implement and with intrinsic limitations to cover large number of individuals and some problems of reliability. Using mobile phone data, we explore the basic characteristics of a model of human travel: The distribution of agents is proportional to the population density of a given region, and each agent has a characteristic trajectory size contain information on frequency of visits to different locations. Additionally we use a complementary data set given by smart subway fare cards offering us information about the exact time of each passenger getting in or getting out of the subway station and the coordinates of it. This allows us to uncover the temporal aspects of the mobility. Since we have the actual time and place of individual's origin and destination we can understand the temporal patterns in each visited location with further details. Integrating two described data set we provide a dynamical model of human travels that incorporates different aspects observed empirically.

  10. Large-scale field trials of active immunizing agents

    PubMed Central

    Cockburn, W. Charles

    1955-01-01

    In this discussion of the methods to be used in large-scale field trials of active immunizing agents and of the results to be expected from such trials, special emphasis is laid on pertussis vaccine trials in Great Britain. After a review of the criteria for strictly controlled field studies and of the investigation of typhoid vaccines conducted in 1904-08 by the Antityphoid Committee of the British Army, the author describes the pertussis vaccine studies which have been and are now being carried by the Whooping-Cough Immunization Committee of the Medical Research Council of Great Britain. The original strictly controlled trials have been completed and the results published. Studies are now being made of vaccines prepared by different methods and evaluated both in the field and in the laboratory. Each vaccine is given to some 2000-3000 children of 4-6 months to 4 years of age. By the end of the studies 30 000-40 000 children will have been followed up for a period of two years. Since in the current studies all the children are vaccinated and none are left as unvaccinated controls, the relative and not the absolute protective value of the vaccines will be measured. PMID:13270079

  11. Active Luminous Blue Variables in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Walborn, Nolan R.; Gamen, Roberto C.; Morrell, Nidia I.; Barbá, Rodolfo H.; Fernández Lajús, Eduardo; Angeloni, Rodolfo

    2017-07-01

    We present extensive spectroscopic and photometric monitoring of two famous and currently highly active luminous blue variables (LBVs) in the Large Magellanic Cloud (LMC), together with more limited coverage of three further, lesser known members of the class. R127 was discovered as an Ofpe/WN9 star in the 1970s but entered a classical LBV outburst in or about 1980 that is still in progress, thus enlightening us about the minimum state of such objects. R71 is currently the most luminous star in the LMC and continues to provide surprises, such as the appearance of [Ca ii] emission lines, as its spectral type becomes unprecedentedly late. Most recently, R71 has developed inverse P Cyg profiles in many metal lines. The other objects are as follows: HDE 269582, now a “second R127” that has been followed from Ofpe/WN9 to A type in its current outburst; HDE 269216, which changed from late B in 2014 to AF in 2016, its first observed outburst; and R143 in the 30 Doradus outskirts. The light curves and spectroscopic transformations are correlated in remarkable detail and their extreme reproducibility is emphasized, both for a given object and among all of them. It is now believed that some LBVs proceed directly to core collapse. One of these unstable LMC objects may thus oblige in the near future, teaching us even more about the final stages of massive stellar evolution.

  12. Internal disruptions and sawtooth like activity in Large Helical Device

    SciTech Connect

    Varela, J.; Garcia, L.; Sanchez, R.; Ohdachi, S.; Watanabe, K. Y.

    2012-08-15

    Large Helical Device (LHD) inward-shifted configurations are unstable to resistive magnetohydrodynamic (MHD) pressure-gradient-driven modes. These modes drive sawtooth like events during LHD operation. In this work, we simulate sawtooth like activity and internal disruptions in order to improve the understanding of these relaxation events and their effect over the device efficiency to confine the plasma, with the aim to improve the LHD present and future operation scenarios minimizing or avoiding the disadvantageous MHD soft and hard limits. By solving a set of reduced non-linear resistive MHD equations, we have studied the evolution of perturbations to equilibria obtained before and after a sawtooth like event in LHD. The equilibrium {beta} value is gradually increased during the simulation until it reaches the experimental value. Sawtooth like events and internal disruption events take place in the simulation for {beta}{sub 0} values between 1% and 1.48%. The main driver of the sawtooth like events is the resonant and non-resonant effect of the (n = 1, m = 3) mode. The instability is stronger for resonant events, and they only appear when {beta}{sub 0} = 1.48%. Internal disruptions are mainly driven by the (n = 1, m = 2) mode, and they extend throughout the whole plasma core. Internal disruption events do not show up when resonant sawtooth like events are triggered.

  13. Is Active Learning Like Broccoli? Student Perceptions of Active Learning in Large Lecture Classes

    ERIC Educational Resources Information Center

    Smith, C. Veronica; Cardaciotto, LeeAnn

    2011-01-01

    Although research suggests that active learning is associated with positive outcomes (e.g., memory, test performance), use of such techniques can be difficult to implement in large lecture-based classes. In the current study, 1,091 students completed out-of-class group exercises to complement course material in an Introductory Psychology class.…

  14. Fermi Large Area Telescope Observations Of Misaligned Active Galactic Nuclei

    DOE PAGES

    Abdo, A. A.

    2010-08-13

    Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sourcesmore » associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.« less

  15. Large deformations of reconfigurable active membranes: a finite element model

    NASA Astrophysics Data System (ADS)

    Son, Seyul; Goulbourne, N. C.

    2010-04-01

    In this paper, a finite element model is used to describe the inhomogeneous deformations of dielectric elastomers (DE). In our previous work, inhomogeneous deformations of the DE with simple boundary conditions represented by a system of highly nonlinear coupled differential equations (ordinary and partial) were solved using numerical approaches [1-3]. To solve for the electromechanical response for complex shapes (asymmetric), nonuniform loading, and complex boundary conditions a finite element scheme is required. This paper describes a finite element implementation of the DE material model proposed in our previous work in a commercial FE code (ABAQUS 6.8-1, PAWTUCKET, R.I, USA). The total stress is postulated as the summation of the elastic stress tensor and the Maxwell stress tensor, or more generally the electrostatic stress tensor. The finite element model is verified by analytical solutions and experimental results for planar membrane extensions subject to mechanical loads and an electric field: (i) equibiaxial extension and (ii) generalized biaxial extension. Specifically, the analytical solutions for equibiaxial extension of the DE is obtained by combining a modified large deformation membrane theory that accounts for the electromechanical coupling effect in actuation commonly referred to as the Maxwell stress [4]. A Mooney-Rivlin strain energy function is employed to describe the constitutive stress strain behavior of the DE. For the finite element implementation, the constitutive relationships from our previously proposed mathematical model [4] are implemented into the finite element code. Experimentally, a 250% equibiaxially prestretched DE sample is attached to a rigid joint frame and inhomogeneous deformations of the reconfigurable DE are observed with respect to mechanical loads and an applied electric field. The computational result for the reconfigurable DE is compared with the test result to validate the accuracy and robustness of the finite

  16. Multistability in Large Scale Models of Brain Activity

    PubMed Central

    Golos, Mathieu; Jirsa, Viktor; Daucé, Emmanuel

    2015-01-01

    Noise driven exploration of a brain network’s dynamic repertoire has been hypothesized to be causally involved in cognitive function, aging and neurodegeneration. The dynamic repertoire crucially depends on the network’s capacity to store patterns, as well as their stability. Here we systematically explore the capacity of networks derived from human connectomes to store attractor states, as well as various network mechanisms to control the brain’s dynamic repertoire. Using a deterministic graded response Hopfield model with connectome-based interactions, we reconstruct the system’s attractor space through a uniform sampling of the initial conditions. Large fixed-point attractor sets are obtained in the low temperature condition, with a bigger number of attractors than ever reported so far. Different variants of the initial model, including (i) a uniform activation threshold or (ii) a global negative feedback, produce a similarly robust multistability in a limited parameter range. A numerical analysis of the distribution of the attractors identifies spatially-segregated components, with a centro-medial core and several well-delineated regional patches. Those different modes share similarity with the fMRI independent components observed in the “resting state” condition. We demonstrate non-stationary behavior in noise-driven generalizations of the models, with different meta-stable attractors visited along the same time course. Only the model with a global dynamic density control is found to display robust and long-lasting non-stationarity with no tendency toward either overactivity or extinction. The best fit with empirical signals is observed at the edge of multistability, a parameter region that also corresponds to the highest entropy of the attractors. PMID:26709852

  17. Geomagnetic Activity Indicates Large Amplitude for Sunspot Cycle 24

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.; Wilson, R. M.

    2006-01-01

    The level of geomagnetic activity near the time of solar activity minimum has been shown to be a reliable indicator for the amplitude of the following solar activity maximum. The geomagnetic activity index aa can be split into two components: one associated with solar flares, prominence eruptions, and coronal mass ejections which follows the solar activity cycle and a second component associated with recurrent high speed solar wind streams which is out of phase with the solar activity cycle. This second component often peaks before solar activity minimum and has been one of the most reliable indicators for the amplitude of the following maximum. The size of the recent maximum in this second component indicates that solar activity cycle 24 will be much higher than average - similar in size to cycles 21 and 22.

  18. A fiber optic synchronization system for LUX

    SciTech Connect

    Wilcox, R.B.; Staples, J.W.; Doolittle, L.R.

    2004-06-30

    The LUX femtosecond light source concept would support pump-probe experiments that need to synchronize laser light pulses with electron-beam-generated X-ray pulses to less than 50 fs at the experimenter endstations. To synchronize multiple endstation lasers with the X-ray pulse, we are developing a fiber-distributed optical timing network. A high frequency clock signal is distributed via fiber to RF cavities (controlling X-ray probe pulse timing) and mode-locked lasers at endstations (controlling pump pulse timing). The superconducting cavities are actively locked to the optical clock phase. Most of the RF timing error is contained within a 10 kHz bandwidth, so these errors and any others affecting X-ray pulse timing (such as RF gun phase) can be detected and transmitted digitally to correct laser timing at the endstations. Time delay through the fibers will be stabilized by comparing a retro-reflected pulse from the experimenter endstation end with a reference pulse from the sending en d, and actively controlling the fiber length.

  19. Reliability issues in active control of large flexible space structures

    NASA Technical Reports Server (NTRS)

    Vandervelde, W. E.

    1983-01-01

    The unreliability of control system components was investigated in our attempt to deal with that problem. This matter is of concern in large space structure control because of the large number of components required to achieve specified performance in some situations, and the long operating period required between maintenance visits. The detection and isolation of component failures during system operation, and algorithms for reconfiguring control systems following detection and isolation of a failure were emphasized.

  20. Active nonsurgical decompression of large periapical lesions--3 case reports.

    PubMed

    Mejia, Jose L; Donado, Jaime E; Basrani, Bettina

    2004-11-01

    This paper describes a new nonsurgical approach for treating large periapical lesions which involves using a modified vacuum system within the root canal space. This new technique produces a vacuum effect in the periapical zone, which facilitates evacuation of large amounts of inflammatory fluids. This technique was used in 3 clinical cases, in which the patients presented with copious amounts of exudate draining from within the root canals. Clinical and radiographic results showed long-term resolution of the endodontic lesions. This treatment of the periapical pathology was consistent with the principles of conservative, nonsurgical endodontic procedures.

  1. Beyond Therapy Dogs: Coordinating Large-Scale Finals Week Activities

    ERIC Educational Resources Information Center

    Flynn, Holly

    2017-01-01

    Finals week activities have become increasingly popular in academic libraries in the last few years, but what is a library to do when it is not allowed to have therapy dogs? This column examines a progression of increasingly popular activities at Michigan State University Libraries. Included is an assessment of what makes them popular, our…

  2. Large Strain Transparent Magneto-Active Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra (Inventor); Meador, Michael A (Inventor)

    2016-01-01

    A large strain polymer nanocomposite actuator is provided that upon subjected to an external stimulus, such as a magnetic field (static or electromagnetic field), an electric field, thermal energy, light, etc., will deform to thereby enable mechanical manipulations of structural components in a remote and wireless manner.

  3. Active control of large space structures: An introduction and overview

    NASA Technical Reports Server (NTRS)

    Doane, G. B., III; Tollison, D. K.; Waites, H. B.

    1985-01-01

    An overview of the large space structure (LSS) control system design problem is presented. The LSS is defined as a class of system, and LSS modeling techniques are discussed. Model truncation, control system objectives, current control law design techniques, and particular problem areas are discussed.

  4. ActiveSeismoPick3D - automatic first arrival determination for large active seismic arrays

    NASA Astrophysics Data System (ADS)

    Paffrath, Marcel; Küperkoch, Ludger; Wehling-Benatelli, Sebastian; Friederich, Wolfgang

    2016-04-01

    We developed a tool for automatic determination of first arrivals in active seismic data based on an approach, that utilises higher order statistics (HOS) and the Akaike information criterion (AIC), commonly used in seismology, but not in active seismics. Automatic picking is highly desirable in active seismics as the number of data provided by large seismic arrays rapidly exceeds of what an analyst can evaluate in a reasonable amount of time. To bring the functionality of automatic phase picking into the context of active data, the software package ActiveSeismoPick3D was developed in Python. It uses a modified algorithm for the determination of first arrivals which searches for the HOS maximum in unfiltered data. Additionally, it offers tools for manual quality control and postprocessing, e.g. various visualisation and repicking functionalities. For flexibility, the tool also includes methods for the preparation of geometry information of large seismic arrays and improved interfaces to the Fast Marching Tomography Package (FMTOMO), which can be used for the prediction of travel times and inversion for subsurface properties. Output files are generated in the VTK format, allowing the 3D visualization of e.g. the inversion results. As a test case, a data set consisting of 9216 traces from 64 shots was gathered, recorded at 144 receivers deployed in a regular 2D array of a size of 100 x 100 m. ActiveSeismoPick3D automatically checks the determined first arrivals by a dynamic signal to noise ratio threshold. From the data a 3D model of the subsurface was generated using the export functionality of the package and FMTOMO.

  5. Molecular Mechanisms of Large-Conductance Ca2+-Activated Potassium Channel Activation by Ginseng Gintonin

    PubMed Central

    Choi, S. H.; Lee, B. H.; Hwang, S. H.; Kim, H. J.; Lee, S. M.; Kim, H. C.; Rhim, H. W.; Nah, S. Y.

    2013-01-01

    Gintonin is a unique lysophosphatidic acid (LPA) receptor ligand found in Panax ginseng. Gintonin induces transient [Ca2+]i through G protein-coupled LPA receptors. Large-conductance Ca2+-activated K+ (BKCa) channels are expressed in blood vessels and neurons and play important roles in blood vessel relaxation and attenuation of neuronal excitability. BKCa channels are activated by transient [Ca2+]i and are regulated by various Ca2+-dependent kinases. We investigated the molecular mechanisms of BKCa channel activation by gintonin. BKCa channels are heterologously expressed in Xenopus oocytes. Gintonin treatment induced BKCa channel activation in oocytes expressing the BKCa channel α subunit in a concentration-dependent manner (EC50 = 0.71 ± 0.08 µg/mL). Gintonin-mediated BKCa channel activation was blocked by a PKC inhibitor, calphostin, and by the calmodulin inhibitor, calmidazolium. Site-directed mutations in BKCa channels targeting CaM kinase II or PKC phosphorylation sites but not PKA phosphorylation sites attenuated gintonin action. Mutations in the Ca2+ bowl and the regulator of K+ conductance (RCK) site also blocked gintonin action. These results indicate that gintonin-mediated BKCa channel activations are achieved through LPA1 receptor-phospholipase C-IP3-Ca2+-PKC-calmodulin-CaM kinase II pathways and calcium binding to the Ca2+ bowl and RCK domain. Gintonin could be a novel contributor against blood vessel constriction and over-excitation of neurons. PMID:23662129

  6. Scaling and Criticality in Large-Scale Neuronal Activity

    NASA Astrophysics Data System (ADS)

    Linkenkaer-Hansen, K.

    The human brain during wakeful rest spontaneously generates large-scale neuronal network oscillations at around 10 and 20 Hz that can be measured non-invasively using magnetoencephalography (MEG) or electroencephalography (EEG). In this chapter, spontaneous oscillations are viewed as the outcome of a self-organizing stochastic process. The aim is to introduce the general prerequisites for stochastic systems to evolve to the critical state and to explain their neurophysiological equivalents. I review the recent evidence that the theory of self-organized criticality (SOC) may provide a unifying explanation for the large variability in amplitude, duration, and recurrence of spontaneous network oscillations, as well as the high susceptibility to perturbations and the long-range power-law temporal correlations in their amplitude envelope.

  7. Hydrodynamic Coating of a Fiber

    NASA Astrophysics Data System (ADS)

    Quéré, D.; de Ryck, A.

    We discuss how a solid (especially a fiber) is coated when drawn out of a bath of liquid. 1. For slow withdrawals out of pure viscous liquids, the data are found to be fitted by the famous Landau law: then, the coating results from a balance between viscosity and capillarity. For quicker withdrawals, the thickness of the entrained film suddenly diverges, at a velocity on order 1 m/s. Inertia is shown to be responsible for this effect. At still higher velocities, the thickness decreases with the velocity because the solid can only entrain the viscous boundary layer. 2. For complex fluids, surface effects are found in the low velocity regime: out of a surfactant solution, films are thicker than predicted by Landau, by a factor of order 2. The thickening factor is shown to be fixed by the Marangoni flow due to the presence of surfactants; out of an emulsion, the film can be enriched with oil , which can be understood by a simple model of capture; out of a polymer solution, a strong swelling of the film is observed if normal stresses are present. Hence, the problem has two families of solution: (i) at low velocity, the thickness of the layer is fixed by a balance between viscous and surface forces and thus is sensitive to the presence of surfactants, or other heterogeneities; (ii) at high velocity, inertia must be considered and the film thickness is fixed by the bulk properties of the liquid (density and viscosity). In these regimes, it is not affected by the presence of surfactants in the bath. Nous décrivons le dépôt de liquide sur un solide (le plus souvent une fibre) qui advient quand on tire ce solide d'un bain. 1. Si le retrait se fait lentement hors d'un liquide pur et visqueux, les données expérimentales suivent la loi de Landau : le dépôt résulte d'un compromis entre forces visqueuses et forces capillaires. Pour des retraits plus rapides, on observe que l'épaisseur du dépôt diverge, pour une vitesse de l'ordre du mètre par seconde. Nous montrons

  8. Active Commuting Patterns at a Large, Midwestern College Campus

    ERIC Educational Resources Information Center

    Bopp, Melissa; Kaczynski, Andrew; Wittman, Pamela

    2011-01-01

    Objective: To understand patterns and influences on active commuting (AC) behavior. Participants: Students and faculty/staff at a university campus. Methods: In April-May 2008, respondents answered an online survey about mode of travel to campus and influences on commuting decisions. Hierarchical regression analyses predicted variance in walking…

  9. Transparent Large Strain Thermoplastic Polyurethane Magneto-Active Nanocomposites

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Carpen, Ileana; Peck, John; Sola, Francisco; Bail, Justin; Lerch, Bradley; Meador, Michael

    2010-01-01

    Smart adaptive materials are an important class of materials which can be used in space deployable structures, morphing wings, and structural air vehicle components where remote actuation can improve fuel efficiency. Adaptive materials can undergo deformation when exposed to external stimuli such as electric fields, thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation, and magnetic field. Large strain, controlled and repetitive actuation are important characteristics of smart adaptive materials. Polymer nanocomposites can be tailored as shape memory polymers and actuators. Magnetic actuation of polymer nanocomposites using a range of iron, iron cobalt, and iron manganese nanoparticles is presented. The iron-based nanoparticles were synthesized using the soft template (1) and Sun's (2) methods. The nanoparticles shape and size were examined using TEM. The crystalline structure and domain size were evaluated using WAXS. Surface modifications of the nanoparticles were performed to improve dispersion, and were characterized with IR and TGA. TPU nanocomposites exhibited actuation for approximately 2wt% nanoparticle loading in an applied magnetic field. Large deformation and fast recovery were observed. These nanocomposites represent a promising potential for new generation of smart materials.

  10. Large-Scale Activity Initiated BY Halo CMEs

    NASA Astrophysics Data System (ADS)

    Chertok, I.; Grechnev, V.

    We summarize results of our recent studies of CME-associated EUV dimmings and coronal waves by `derotated' fixed-difference SOHO/EIT heliograms at 195 Å with 12-min intervals and at 171, 195, 284, 304 Å with 6-h intervals. Correctness of the derotated fixed-difference technique is confirmed by the consideration of the Bastille Day 2000 event. We also demonstrate that long narrow channeled dimmings and anisotropic coronal waves are typical of the complex global solar magnetosphere near the solar cycle maximum. Homology of large-scale dimmings and coronal waves takes place in a series of recurrent eruptive events. Along with dimmings coinciding entirely or partially in all four EIT bands, there exist dimmings that appear different, mainly in the transition-region line of 304 Å and high-temperature coronal line of 284 Å.

  11. Zn2+ activates large conductance Ca2+-activated K+ channel via an intracellular domain.

    PubMed

    Hou, Shangwei; Vigeland, Leif E; Zhang, Guangping; Xu, Rong; Li, Min; Heinemann, Stefan H; Hoshi, Toshinori

    2010-02-26

    Zinc is an essential trace element and plays crucial roles in normal development, often as an integral structural component of transcription factors and enzymes. Recent evidence suggests that intracellular Zn(2+) functions as a signaling molecule, mediating a variety of important physiological phenomena. However, the immediate effectors of intracellular Zn(2+) signaling are not well known. We show here that intracellular Zn(2+) potently and reversibly activates large-conductance voltage- and Ca(2+)-activated Slo1 K(+) (BK) channels. The full effect of Zn(2+) requires His(365) in the RCK1 (regulator of conductance for K(+)) domain of the channel. Furthermore, mutation of two nearby acidic residues, Asp(367) and Glu(399), also reduced activation of the channel by Zn(2+), suggesting a possible structural arrangement for Zn(2+) binding by the aforementioned residues. Extracellular Zn(2+) activated Slo1 BK channels when coexpressed with Zn(2+)-permeable TRPM7 (transient receptor potential melastatin 7) channels. The results thus demonstrate that Slo1 BK channels represent a positive and direct effector of Zn(2+) signaling and may participate in sculpting cellular response to an increase in intracellular Zn(2+) concentration.

  12. When and how to activate large new hydropower reservoirs

    NASA Astrophysics Data System (ADS)

    Geressu, Robel; Harou, Julien

    2016-04-01

    Water resources system planners are increasingly required to address multiple long and short-term management objectives and the trade-offs these imply. Expansion planning in hydropower reservoir systems, where assets either temporarily or permanently reduce each other's performance, is a complex and potentially conflictual task requiring attention to multiple impacts. This paper proposes a multi-criteria scheduling approach considering many objectives and their associated uncertainties. The method considers the coordination and flexibility of reservoir operation in different expansion stages. The impact of abstraction (i.e., during filling of new reservoirs) and regulation of inflows by upstream reservoirs, is represented by simultaneously optimizing the storage size of reservoirs. Sensitivity analysis of performance given financial uncertainty and hydrological variability reveals which expansion schedules are robust to a wide range of future conditions. This informs how alternative designs compare in multiple performance dimensions and can serve stakeholders with differing attitudes towards risk and opportunity. The method is applied to proposed Blue Nile hydropower reservoirs to find efficient new dam activation schedules considering energy revenues, downstream release requirements, and energy generation during reservoir filling periods. Results take the form of Pareto-optimal trade-offs where each point on the curve or surface represents asset choices, size, activation date, and filling period reservoir operating rules. The results help explore the complex planning and management issues involved in the Blue Nile and demonstrate a possible approach to negotiate the design, filling and coordinated use of hydropower reservoirs.

  13. LARGE PARTICLES IN ACTIVE ASTEROID P/2010 A2

    SciTech Connect

    Jewitt, David; Ishiguro, Masateru; Agarwal, Jessica

    2013-02-10

    The previously unknown asteroid P/2010 A2 rose to prominence in 2010 by forming a transient, comet-like tail consisting of ejected dust. The observed dust production was interpreted as the result of either a hypervelocity impact with a smaller body or a rotational disruption. We have re-observed this object, finding that large particles remain a full orbital period after the initial outburst. In the intervening years, particles smaller than {approx}3 mm in radius have been dispersed by radiation pressure, leaving only larger particles in the trail. Since the total mass is dominated by the largest particles, the radiation pressure filtering allows us to obtain a more reliable estimate of the debris mass than was previously possible. We find that the mass contained in the debris is {approx}5 Multiplication-Sign 10{sup 8} kg (assumed density 3000 kg m{sup -3}), the ratio of the total debris mass to the nucleus mass is {approx}0.1, and that events like P/2010 A2 contribute <3% to the Zodiacal dust production rate. Physical properties of the nucleus and debris are also determined.

  14. Active assembly for large-scale manufacturing of integrated nanostructures.

    SciTech Connect

    Spoerke, Erik David; Bunker, Bruce Conrad; Orendorff, Christopher J.; Bachand, George David; Hendricks, Judy K.; Matzke, Carolyn M.

    2007-01-01

    Microtubules and motor proteins are protein-based biological agents that work cooperatively to facilitate the organization and transport of nanomaterials within living organisms. This report describes the application of these biological agents as tools in a novel, interdisciplinary scheme for assembling integrated nanostructures. Specifically, selective chemistries were used to direct the favorable adsorption of active motor proteins onto lithographically-defined gold electrodes. Taking advantage of the specific affinity these motor proteins have for microtubules, the motor proteins were used to capture polymerized microtubules out of suspension to form dense patterns of microtubules and microtubule bridges between gold electrodes. These microtubules were then used as biofunctionalized templates to direct the organization of functionalized nanocargo including single-walled carbon nanotubes and gold nanoparticles. This biologically-mediated scheme for nanomaterials assembly has shown excellent promise as a foundation for developing new biohybrid approaches to nanoscale manufacturing.

  15. Multidisciplinary analysis of actively controlled large flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Cooper, Paul A.; Young, John W.; Sutter, Thomas R.

    1986-01-01

    The control of Flexible Structures (COFS) program has supported the development of an analysis capability at the Langley Research Center called the Integrated Multidisciplinary Analysis Tool (IMAT) which provides an efficient data storage and transfer capability among commercial computer codes to aid in the dynamic analysis of actively controlled structures. IMAT is a system of computer programs which transfers Computer-Aided-Design (CAD) configurations, structural finite element models, material property and stress information, structural and rigid-body dynamic model information, and linear system matrices for control law formulation among various commercial applications programs through a common database. Although general in its formulation, IMAT was developed specifically to aid in the evaluation of the structures. A description of the IMAT system and results of an application of the system are given.

  16. Measurements in large pool fires with an actively cooled calorimeter

    SciTech Connect

    Koski, J.A.; Wix, S.D.

    1995-12-31

    The pool fire thermal test described in Safety Series 6 published by the International Atomic Energy Agency (IAEA) or Title 10, Code of Federal Regulations, Part 71 (10CFR71) in the United States is one of the most difficult tests that a container for larger ``Type B`` quantities of nuclear materials must pass. If retests of a container are required, costly redesign and project delays can result. Accurate measurements and modeling of the pool fire environment will ultimately lower container costs by assuring that containers past the pool fire test on the first attempt. Experiments indicate that the object size or surface temperature of the container can play a role in determining local heat fluxes that are beyond the effects predicted from the simple radiative heat transfer laws. An analytical model described by Nicolette and Larson 1990 can be used to understand many of these effects. In this model a gray gas represents soot particles present in the flame structure. Close to the container surface, these soot particles are convectively and radiatively cooled and interact with incident energy from the surrounding fire. This cooler soot cloud effectively prevents some thermal radiation from reaching the container surface, reducing the surface heat flux below the value predicted by a transparent medium model. With some empirical constants, the model suggested by Nicolette and Larson can be used to more accurately simulate the pool fire environment. Properly formulated, the gray gas approaches also fast enough to be used with standard commercial computer codes to analyze shipping containers. To calibrate this type of model, accurate experimental measurements of radiative absorption coefficients, flame temperatures, and other parameters are necessary. A goal of the calorimeter measurements described here is to obtain such parameters so that a fast, useful design tool for large pool fires can be constructed.

  17. Analysis and Management of Large-Scale Activities Based on Interface

    NASA Astrophysics Data System (ADS)

    Yang, Shaofan; Ji, Jingwei; Lu, Ligang; Wang, Zhiyi

    Based on the concepts of system safety engineering, life-cycle and interface that comes from American system safety standard MIL-STD-882E, and apply them to the process of risk analysis and management of large-scale activities. Identify the involved personnel, departments, funds and other contents throughout the life cycle of large-scale activities. Recognize and classify the ultimate risk sources of people, objects and environment of large-scale activities from the perspective of interface. Put forward the accident cause analysis model according to the previous large-scale activities' accidents and combine with the analysis of the risk source interface. Analyze the risks of each interface and summary various types of risks the large-scale activities faced. Come up with the risk management consciousness, policies and regulations, risk control and supervision departments improvement ideas.

  18. A novel method for the activity measurement of large-area beta reference sources.

    PubMed

    Stanga, D; De Felice, P; Keightley, J; Capogni, M; Ioan, M R

    2016-03-01

    A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity.

  19. [Coordination of the myoelectrical activity of the large and small intestine].

    PubMed

    Lychkova, A E

    2012-01-01

    Coordination of the myoelectrical activity of the large and small intestine was studied. Pacemaker cells of intestine are predominantly located at the proximal divisions of large and small intestine and have an increased spontaneous slow-wave activity, which ensures the distribution of excitation in smooth muscle underlying intestines. Due to the ileocecal coordination by sequential motor activity of small and large intestine is provided. The distal direction gradient of slow waves frequency reduction was established. Pacemaker cells possess certain structural specificity and is specialized in the spontaneous bioelectric activity.

  20. Facilitating Active Engagement of the University Student in a Large-Group Setting Using Group Work Activities

    ERIC Educational Resources Information Center

    Kinsella, Gemma K.; Mahon, Catherine; Lillis, Seamus

    2017-01-01

    It is envisaged that small-group exercises as part of a large-group session would facilitate not only group work exercises (a valuable employability skill), but also peer learning. In this article, such a strategy to facilitate the active engagement of the student in a large-group setting was explored. The production of student-led resources was…

  1. Large space antenna communications systems: Integrated Langley Research Center/Jet Propulsion Laboratory development activities. 2: Langley Research Center activities

    NASA Technical Reports Server (NTRS)

    Cambell, T. G.; Bailey, M. C.; Cockrell, C. R.; Beck, F. B.

    1983-01-01

    The electromagnetic analysis activities at the Langley Research Center are resulting in efficient and accurate analytical methods for predicting both far- and near-field radiation characteristics of large offset multiple-beam multiple-aperture mesh reflector antennas. The utilization of aperture integration augmented with Geometrical Theory of Diffraction in analyzing the large reflector antenna system is emphasized.

  2. Research on elastic large space structures as "plants' for active control

    NASA Technical Reports Server (NTRS)

    Ashley, H.; Vonflotow, A.

    1983-01-01

    Research on active control of large space structures is discussed. Intrinsic damping in monolithic metallic structures is discussed. Thermal relaxation and grain boundary relaxation are discussed, as are properties of thermal damping.

  3. A Fundamental Study for Efficient Implementaion of Online Collaborative Activities in Large-Scale Classes

    ERIC Educational Resources Information Center

    Matsuba, Ryuichi; Suzuki, Yusei; Kubota, Shin-Ichiro; Miyazaki, Makoto

    2015-01-01

    We study tactics for writing skills development through cross-disciplinary learning in online large-scale classes, and particularly are interested in implementation of online collaborative activities such as peer reviewing of writing. The goal of our study is to carry out collaborative works efficiently via online effectively in large-scale…

  4. Passive and Active Vibrations Allow Self-Organization in Large-Scale Electromechanical Systems

    NASA Astrophysics Data System (ADS)

    Buscarino, Arturo; Fortuna, Carlo Famoso Luigi; Frasca, Mattia

    2016-06-01

    In this paper, the role of passive and active vibrations for the control of nonlinear large-scale electromechanical systems is investigated. The mathematical model of the system is discussed and detailed experimental results are shown in order to prove that coupling the effects of feedback and vibrations elicited by proper control signals makes possible to regularize imperfect uncertain large-scale systems.

  5. A fiber optic sensor for nerve agent

    NASA Astrophysics Data System (ADS)

    Cordero, Steven R.; Mukamal, Harold; Low, Aaron; Locke, Edward P.; Lieberman, Robert A.

    2006-10-01

    We report advances made on the development of a fiber optic nerve agent sensor having its entire length as the sensing element. The optical fiber is multimode, and consists of a fused-silica core and a nerve agent sensitive cladding. Upon exposure to sarin gas, the cladding changes color, resulting in an alteration of the light intensity throughput. The fiber is mass produced using a conventional fiber optic draw tower. This technology could replace, or be used with, a collection of point-detectors to protect personnel, buildings and perimeters from dangerous chemical attacks.

  6. Fc receptor triggering induces expression of surface activation antigens and release of platelet-activating factor in large granular lymphocytes.

    PubMed Central

    Malavasi, F; Tetta, C; Funaro, A; Bellone, G; Ferrero, E; Franzone, A C; Dellabona, P; Rusci, R; Matera, L; Camussi, G

    1986-01-01

    Triggering of large granular lymphocyte (LGL) Fc receptor with a specific monoclonal antibody (AB8.28) linked to an insoluble matrix induces cell activation, as witnessed by expression of HLA class II (DR and DQ) molecules and interleukin 2 receptor. Moreover, this event is accompanied by a concomitant release of platelet-activating factor by LGL. We conclude that the Fc receptor molecule identified by mAb AB8.28 represents a trigger for LGL activation. PMID:3085094

  7. Implementing Experiential Learning Activities in a Large Enrollment Introductory Food Science and Human Nutrition Course

    ERIC Educational Resources Information Center

    Bohn, Dawn M.; Schmidt, Shelly J.

    2008-01-01

    Experiential learning activities are often viewed as impractical, and potentially unfeasible, instructional tools to employ in a large enrollment course. Research has shown, though, that the metacognitive skills that students utilize while participating in experiential learning activities enable them to assess their true level of understanding and…

  8. Implementing Experiential Learning Activities in a Large Enrollment Introductory Food Science and Human Nutrition Course

    ERIC Educational Resources Information Center

    Bohn, Dawn M.; Schmidt, Shelly J.

    2008-01-01

    Experiential learning activities are often viewed as impractical, and potentially unfeasible, instructional tools to employ in a large enrollment course. Research has shown, though, that the metacognitive skills that students utilize while participating in experiential learning activities enable them to assess their true level of understanding and…

  9. Introductory Biology Courses: A Framework to Support Active Learning in Large Enrollment Introductory Science Courses

    ERIC Educational Resources Information Center

    Smith, Ann C.; Stewart, Richard; Shields, Patricia; Hayes-Klosteridis, Jennifer; Robinson, Paulette; Yuan, Robert

    2005-01-01

    Active learning and research-oriented activities have been increasingly used in smaller, specialized science courses. Application of this type of scientific teaching to large enrollment introductory courses has been, however, a major challenge. The general microbiology lecture/laboratory course described has been designed to incorporate published…

  10. ActivitySim: large-scale agent based activity generation for infrastructure simulation

    SciTech Connect

    Gali, Emmanuel; Eidenbenz, Stephan; Mniszewski, Sue; Cuellar, Leticia; Teuscher, Christof

    2008-01-01

    The United States' Department of Homeland Security aims to model, simulate, and analyze critical infrastructure and their interdependencies across multiple sectors such as electric power, telecommunications, water distribution, transportation, etc. We introduce ActivitySim, an activity simulator for a population of millions of individual agents each characterized by a set of demographic attributes that is based on US census data. ActivitySim generates daily schedules for each agent that consists of a sequence of activities, such as sleeping, shopping, working etc., each being scheduled at a geographic location, such as businesses or private residences that is appropriate for the activity type and for the personal situation of the agent. ActivitySim has been developed as part of a larger effort to understand the interdependencies among national infrastructure networks and their demand profiles that emerge from the different activities of individuals in baseline scenarios as well as emergency scenarios, such as hurricane evacuations. We present the scalable software engineering principles underlying ActivitySim, the socia-technical modeling paradigms that drive the activity generation, and proof-of-principle results for a scenario in the Twin Cities, MN area of 2.6 M agents.

  11. Large-scale assessment of activity landscape feature probabilities of bioactive compounds.

    PubMed

    Kayastha, Shilva; Dimova, Dilyana; Iyer, Preeti; Vogt, Martin; Bajorath, Jürgen

    2014-02-24

    Activity landscape representations integrate pairwise compound similarity and potency relationships and provide direct access to characteristic structure-activity relationship features in compound data sets. Because pairwise compound comparisons provide the foundation of activity landscape design, the assessment of specific landscape features such as activity cliffs has generally been confined to the level of compound pairs. A conditional probability-based approach has been applied herein to assign most probable activity landscape features to individual compounds. For example, for a given data set compound, it was determined if it would preferentially engage in the formation of activity cliffs or other landscape features. In a large-scale effort, we have determined conditional activity landscape feature probabilities for more than 160,000 compounds with well-defined activity annotations contained in 427 different target-based data sets. These landscape feature probabilities provide a detailed view of how different activity landscape features are distributed over currently available bioactive compounds.

  12. Structural-optical integrated analysis on the large aperture mirror with active mounting

    NASA Astrophysics Data System (ADS)

    Ren, Zhiyuan; Zhu, Jianqiang; Liu, Zhigang

    2016-11-01

    Deformation of the large aperture mirror caused by the external environment load seriously affects the optical performance of the optical system, and there is a limit to develop the shape quality of large aperture mirror with traditional mounting method. It is effective way to reduce the optical mirror distortion with active support method, and the structural-optical integrated method is the effective means to assess the merits of the mounting for large aperture mirror. Firstly, we proposes a new support scheme that uses specific boundary constraints on the large lens edges and imposes flexible torque to resist deformation induced by gravity to improve surface quantity of large aperture mirror. We calculate distortion of the large aperture mirror at the edges of the flexible torque respectively with the finite element method; secondly, we extract distortion value within clear aperture of the mirror with MATLAB, solve the corresponding Zernike polynomial coefficients; lastly, we obtain the peak-valley value (PV) and root mean square value (RMS) with optical-structural integrated analysis . The results for the 690x400x100mm mirror show that PV and RMS values within the clear aperture with 0.4MPa torques than the case without applying a flexible torque reduces 82.7% and 72.9% respectively. The active mounting on the edge of the large aperture mirror can greatly improve the surface quality of the large aperture mirror.

  13. A large-conductance calcium-activated potassium channel in potato (Solanum tuberosum) tuber mitochondria.

    PubMed

    Koszela-Piotrowska, Izabela; Matkovic, Karolina; Szewczyk, Adam; Jarmuszkiewicz, Wieslawa

    2009-11-11

    In the present study, we describe the existence of a novel potassium channel in the plant [potato (Solanum tuberosum) tuber] mitochondrial inner membrane. We found that substances known to modulate large-conductance calcium-activated potassium channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 {1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-ben-zimidazole-2-one; a potassium channel opener} were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a potassium channel inhibitor) in a potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance potassium channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance potassium channel activity with conductance from 502+/-15 to 615+/-12 pS. The probability of channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma-membrane large-conductance Ca2+-dependent K+ channel identified a pore-forming alpha subunit and an auxiliary beta2 subunit of the channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance calcium-activated potassium channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.

  14. Large sample neutron activation analysis: a challenge in cultural heritage studies.

    PubMed

    Stamatelatos, Ion E; Tzika, Faidra

    2007-07-01

    Large sample neutron activation analysis compliments and significantly extends the analytical tools available for cultural heritage and authentication studies providing unique applications of non-destructive, multi-element analysis of materials that are too precious to damage for sampling purposes, representative sampling of heterogeneous materials or even analysis of whole objects. In this work, correction factors for neutron self-shielding, gamma-ray attenuation and volume distribution of the activity in large volume samples composed of iron and ceramic material were derived. Moreover, the effect of inhomogeneity on the accuracy of the technique was examined.

  15. Coherence and information in a fiber interferometer

    NASA Astrophysics Data System (ADS)

    Kellerer, Aglaé; Wright, Sidney; Lacour, Sylvestre

    2017-01-01

    We present an experiment based on a fibered Mach-Zehnder interferometer, with the aim of familiarizing students with fibered optics and interferometry, and of improving their understanding of optical amplification. The laboratory project has two parts. In the first, students modulate the optical path of the interferometer to study the spectra of light sources via Fourier Transform Spectroscopy. In the second, an optical amplifier is placed in one or both arms of the interferometer. The set-up uses monomode, polarization-maintaining fibers that propagate light with a wavelength of 1.5 μm. Here, we describe the set-up and the analysis of the measurements, and we present results from student reports.

  16. Ages of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region, Russia

    NASA Astrophysics Data System (ADS)

    Braitseva, O. A.; Melekestsev, I. V.; Ponomareva, V. V.; Sulerzhitsky, L. D.

    1995-12-01

    The ages of most of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region have been determined by extensive geological, geomorphological, tephrochronological and isotopic geochronological studies, including more than 600 14C dates. Eight ‘Krakatoa-type’ and three ‘Hawaiian-type’ calderas and no less than three large explosive craters formed here during the Holocene. Most of the Late Pleistocene Krakatoa-type calderas were established around 30 000 40 000 years ago. The active volcanoes are geologically very young, with maximum ages of about 40 000 50 000 years. The overwhelming majority of recently active volcanic cones originated at the very end of the Late Pleistocene or in the Holocene. These studies show that all Holocene stratovolcanoes in Kamchatka were emplaced in the Holocene only in the Eastern volcanic belt. Periods of synchronous, intensified Holocene volcanic activity occurred within the time intervals of 7500 7800 and 1300 1800 14C years BP.

  17. Contacts with large, active individuals intensify the predation risk of small conspecifics.

    PubMed

    Yamaguchi, Aya; Takatsu, Kunio; Kishida, Osamu

    2016-11-01

    Size variation within a population can influence the structure of ecosystem interactions, because ecological performance differs between individuals of different sizes. Although the impact of size variation in a predator species on the structure of interactions is well understood, our knowledge about how size variation in a prey species might modify the interactions between predators and prey is very limited. Here, by examining the interactions between predatory Hynobius retardatus salamander larvae and their prey, Rana pirica frog tadpoles, we investigated how large prey individuals affect the predation mortality of small prey conspecifics. First, in an experiment conducted in a field pond in which we manipulated the presence of salamanders and large tadpoles (i.e., large enough to protect them against salamander predation) with small tadpoles, we showed that in the presence of large tadpoles the mortality of small tadpoles from salamander predation was increased. On the basis of our observations of the activity of individuals, we hypothesized that active large tadpoles caused physical disturbances, which in turn caused the small tadpoles to move, and thus increased their encounter frequency with the predatory salamanders. To test this hypothesis, we conducted a laboratory experiment in small tanks with three players (i.e., one salamander as predator, one small tadpole as focal prey, and either a small or a large tadpole as the prospective movement inducer). In each tank, we manipulated the presence or absence of a movement inducer, and, when present, its size (large or small) and access (caged or uncaged) to the focal prey. In the presence of a large, uncaged movement inducer, the focal prey was more active and suffered from higher predation mortality compared with the other treatments, because the large movement inducer (unlike a small movement inducer) moved actively and, when uncaged, could stimulate movement of the focal prey through direct contact. The

  18. Support of an Active Science Project by a Large Information System: Lessons for the EOS Era

    NASA Technical Reports Server (NTRS)

    Angelici, Gary L.; Skiles, J. W.; Popovici, Lidia Z.

    1993-01-01

    The ability of large information systems to support the changing data requirements of active science projects is being tested in a NASA collaborative study. This paper briefly profiles both the active science project and the large information system involved in this effort and offers some observations about the effectiveness of the project support. This is followed by lessons that are important for those participating in large information systems that need to support active science projects or that make available the valuable data produced by these projects. We learned in this work that it is difficult for a large information system focused on long term data management to satisfy the requirements of an on-going science project. For example, in order to provide the best service, it is important for all information system staff to keep focused on the needs and constraints of the scientists in the development of appropriate services. If the lessons learned in this and other science support experiences are not applied by those involved with large information systems of the EOS (Earth Observing System) era, then the final data products produced by future science projects may not be robust or of high quality, thereby making the conduct of the project science less efficacious and reducing the value of these unique suites of data for future research.

  19. Support of an Active Science Project by a Large Information System: Lessons for the EOS Era

    NASA Technical Reports Server (NTRS)

    Angelici, Gary L.; Skiles, J. W.; Popovici, Lidia Z.

    1993-01-01

    The ability of large information systems to support the changing data requirements of active science projects is being tested in a NASA collaborative study. This paper briefly profiles both the active science project and the large information system involved in this effort and offers some observations about the effectiveness of the project support. This is followed by lessons that are important for those participating in large information systems that need to support active science projects or that make available the valuable data produced by these projects. We learned in this work that it is difficult for a large information system focused on long term data management to satisfy the requirements of an on-going science project. For example, in order to provide the best service, it is important for all information system staff to keep focused on the needs and constraints of the scientists in the development of appropriate services. If the lessons learned in this and other science support experiences are not applied by those involved with large information systems of the EOS (Earth Observing System) era, then the final data products produced by future science projects may not be robust or of high quality, thereby making the conduct of the project science less efficacious and reducing the value of these unique suites of data for future research.

  20. Managing Active Learning Processes in Large First Year Physics Classes: The Advantages of an Integrated Approach

    ERIC Educational Resources Information Center

    Drinkwater, Michael J.; Gannaway, Deanne; Sheppard, Karen; Davis, Matthew J.; Wegener, Margaret J.; Bowen, Warwick P.; Corney, Joel F.

    2014-01-01

    Turning lectures into interactive, student-led question and answer sessions is known to increase learning, but enabling interaction in a large class seems an insurmountable task. This can discourage adoption of this new approach -- who has time to individualize responses, address questions from over 200 students and encourage active participation…

  1. Implementation and Evaluation of a Values Clarification Activity for a Large Undergraduate Human Sexuality Course

    ERIC Educational Resources Information Center

    Lederer, Alyssa M.

    2016-01-01

    Values clarification is an important tool that helps individuals to clarify their beliefs about sexuality-related issues. This lesson plan provides instructions for a 1-hour values clarification activity for a large undergraduate human sexuality course that serves as an introduction to course content and tone, stimulates students' initial thinking…

  2. A Simple and Effective Protein Folding Activity Suitable for Large Lectures

    ERIC Educational Resources Information Center

    White, Brian

    2006-01-01

    This article describes a simple and inexpensive hands-on simulation of protein folding suitable for use in large lecture classes. This activity uses a minimum of parts, tools, and skill to simulate some of the fundamental principles of protein folding. The major concepts targeted are that proteins begin as linear polypeptides and fold to…

  3. Using Technology To Implement Active Learning in Large Classes. Technical Report.

    ERIC Educational Resources Information Center

    Gerace, William J.; Dufresne, Robert J.; Leonard, William J.

    An emerging technology, classroom communication systems (CCSs), has the potential to transform the way we teach science in large-lecture settings. CCSs can serve as catalysts for creating a more interactive, student-centered classroom in the lecture hall, thereby allowing students to become more actively involved in constructing and using…

  4. A Simple and Effective Protein Folding Activity Suitable for Large Lectures

    ERIC Educational Resources Information Center

    White, Brian

    2006-01-01

    This article describes a simple and inexpensive hands-on simulation of protein folding suitable for use in large lecture classes. This activity uses a minimum of parts, tools, and skill to simulate some of the fundamental principles of protein folding. The major concepts targeted are that proteins begin as linear polypeptides and fold to…

  5. Active Learning in a Large Medical Classroom Setting for Teaching Renal Physiology

    ERIC Educational Resources Information Center

    Dietz, John R.; Stevenson, Frazier T.

    2011-01-01

    In this article, the authors describe an active learning exercise which has been used to replace some lecture hours in the renal portion of an integrated, organ system-based curriculum for first-year medical students. The exercise takes place in a large auditorium with ~150 students. The authors, who are faculty members, lead the discussions,…

  6. Implementation and Evaluation of a Values Clarification Activity for a Large Undergraduate Human Sexuality Course

    ERIC Educational Resources Information Center

    Lederer, Alyssa M.

    2016-01-01

    Values clarification is an important tool that helps individuals to clarify their beliefs about sexuality-related issues. This lesson plan provides instructions for a 1-hour values clarification activity for a large undergraduate human sexuality course that serves as an introduction to course content and tone, stimulates students' initial thinking…

  7. Chronic, Wireless Recordings of Large Scale Brain Activity in Freely Moving Rhesus Monkeys

    PubMed Central

    Schwarz, David A.; Lebedev, Mikhail A.; Hanson, Timothy L.; Dimitrov, Dragan F.; Lehew, Gary; Meloy, Jim; Rajangam, Sankaranarayani; Subramanian, Vivek; Ifft, Peter J.; Li, Zheng; Ramakrishnan, Arjun; Tate, Andrew; Zhuang, Katie; Nicolelis, Miguel A.L.

    2014-01-01

    Advances in techniques for recording large-scale brain activity contribute to both the elucidation of neurophysiological principles and the development of brain-machine interfaces (BMIs). Here we describe a neurophysiological paradigm for performing tethered and wireless large-scale recordings based on movable volumetric three-dimensional (3D) multielectrode implants. This approach allowed us to isolate up to 1,800 units per animal and simultaneously record the extracellular activity of close to 500 cortical neurons, distributed across multiple cortical areas, in freely behaving rhesus monkeys. The method is expandable, in principle, to thousands of simultaneously recorded channels. It also allows increased recording longevity (5 consecutive years), and recording of a broad range of behaviors, e.g. social interactions, and BMI paradigms in freely moving primates. We propose that wireless large-scale recordings could have a profound impact on basic primate neurophysiology research, while providing a framework for the development and testing of clinically relevant neuroprostheses. PMID:24776634

  8. Reported frequency of physical activity in a large epidemiological study: relationship to specific activities and repeatability over time

    PubMed Central

    2011-01-01

    Background How overall physical activity relates to specific activities and how reported activity changes over time may influence interpretation of observed associations between physical activity and health. We examine the relationships between various physical activities self-reported at different times in a large cohort study of middle-aged UK women. Methods At recruitment, Million Women Study participants completed a baseline questionnaire including questions on frequency of strenuous and of any physical activity. About 3 years later 589,896 women also completed a follow-up questionnaire reporting the hours they spent on a range of specific activities. Time spent on each activity was used to estimate the associated excess metabolic equivalent hours (MET-hours) and this value was compared across categories of physical activity reported at recruitment. Additionally, 18,655 women completed the baseline questionnaire twice, at intervals of up to 4 years; repeatability over time was assessed using the weighted kappa coefficient (κweighted) and absolute percentage agreement. Results The average number of hours per week women reported doing specific activities was 14.0 for housework, 4.5 for walking, 3.0 for gardening, 0.2 for cycling, and 1.4 for all strenuous activity. Time spent and the estimated excess MET-hours associated with each activity increased with increasing frequency of any or strenuous physical activity reported at baseline (tests for trend, P < 0.003), although the associations for housework were by far the weakest (Spearman correlations, 0.01 and -0.03 respectively for housework, and 0.11-0.37 for all other activities). Repeatability of responses to physical activity questions on the baseline questionnaire declined significantly over time. For strenuous activity, absolute agreement was 64% (κweighted = 0.71) for questionnaires administered less than 6 months apart, and 52% (κweighted = 0.51) for questionnaires more than 2 years apart. Corresponding

  9. Helper activity by human large granular lymphocytes in in vitro immunoglobulin synthesis.

    PubMed

    Rodriguez, M A; Blanca, I; Baroja, M L; Arama, S; Leon-Ponte, M; Abadi, I; Bianco, N E

    1987-09-01

    In the present study we have examined the effect of human large granular lymphocytes (LGL) from healthy donors on Ig synthesis by autologous B lymphocytes. The results showed that this cell population has a consistent helper activity in pokeweed mitogen-activated cultures even when added at very low numbers. LGL can mediate their effect by secreting soluble helper factors capable of modulating B-cell responses as evidenced by the enhancement of IgG and IgM production by supernatants obtained from LGL cultures. Preincubation with interferon gamma further potentiated the helper activity by LGL.

  10. Drought effects on large fire activity in Canadian and Alaskan forests

    NASA Astrophysics Data System (ADS)

    Xiao, Jingfeng; Zhuang, Qianlai

    2007-10-01

    Fire is the dominant disturbance in forest ecosystems across Canada and Alaska, and has important implications for forest ecosystems, terrestrial carbon dioxide emissions and the forestry industry. Large fire activity had increased in Canadian and Alaskan forests during the last four decades of the 20th century. Here we combined the Palmer Drought Severity Index and historical large fire databases to demonstrate that Canada and Alaska forest regions experienced summer drying over this time period, and drought during the fire season significantly affected forest fire activity in these regions. Climatic warming, positive geopotential height anomalies and ocean circulation patterns were spatially and temporally convolved in causing drought conditions, which in turn enhanced fuel flammability and thereby indirectly affected fire activity. Future fire regimes will likely depend on drought patterns under global climate change scenarios.

  11. Process effects on activated carbon with large specific surface area from corn cob.

    PubMed

    Cao, Qing; Xie, Ke-Chang; Lv, Yong-Kang; Bao, Wei-Ren

    2006-01-01

    The main factors that affect the large specific surface area (SSA) of the activated carbon from agricultural waste corn cobs were studied by chemically activated method with solution of KOH and soap which acted as surfactant. The experiment showed that not only the activation temperature, activation time and the mass ratio of KOH to the carbonized material, but also the activated methods using activator obviously influenced the SSA of activated carbon. The experimental operating conditions were as follows: the carbonized temperature being 450 degrees C and keeping time being 4 h using N2 as protective gas; the activation temperature being 850 degrees C and holding time being 1.2 h; the mass ratio of KOH to carbonized material being 4.0; the time of soaking carbonized material in the solution of KOH and soap being 30 min. Under the optimal conditions, the SSA of activated carbon from corn cobs reached 2700 m2/g. And the addition of the soap as surfactant may shorten the soaking time. The structure of the activated carbon prepared had narrow distribution of pore size and the micro-pores accounted for 78%. The advantages of the method described were easy and feasible.

  12. Active Control of Combustion Instability in a Ramjet Using Large-Eddy Simulations

    DTIC Science & Technology

    1992-09-01

    INSTABILITY IN A RAMJET USING LARGE-EDDY SIMULATIONS S. Menon N.TIS CR.A,1i ()TiC TAB September 1992 1 , o -d 6 y ... . ... .. Prepared for t.Cft OFFICE OF...pressure oscillations initially show a large-aznplitude, low- frequency oscillatio that eventually decays o that a high-frequency oscillation at around...injec- tion were recently presented (M o ., 199•1) TP-276/02-91 10 4.1 Acsntlc Fedback Cesto l Active control through acoustic forcing was demonstrated

  13. Large-scale filament formation inhibits the activity of CTP synthetase

    PubMed Central

    Barry, Rachael M; Bitbol, Anne-Florence; Lorestani, Alexander; Charles, Emeric J; Habrian, Chris H; Hansen, Jesse M; Li, Hsin-Jung; Baldwin, Enoch P; Wingreen, Ned S; Kollman, Justin M; Gitai, Zemer

    2014-01-01

    CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable. DOI: http://dx.doi.org/10.7554/eLife.03638.001 PMID:25030911

  14. Large-scale filament formation inhibits the activity of CTP synthetase.

    PubMed

    Barry, Rachael M; Bitbol, Anne-Florence; Lorestani, Alexander; Charles, Emeric J; Habrian, Chris H; Hansen, Jesse M; Li, Hsin-Jung; Baldwin, Enoch P; Wingreen, Ned S; Kollman, Justin M; Gitai, Zemer

    2014-07-16

    CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable.

  15. Gain characteristics of large volume CuBr laser active media

    NASA Astrophysics Data System (ADS)

    Gubarev, F. A.; Troitskiy, V. O.; Trigub, M. V.; Sukhanov, V. B.

    2011-05-01

    The paper presents the experimental results on how the active additive HBr and the temperatures of the containers with CuBr influence the gain characteristics of large volume (8 cm bore, 90 cm long) CuBr laser active media with the external heating of the active zone of the gas discharge tube (GDT). It has been demonstrated that an increase in the concentration of CuBr vapors results in the contraction of the gain profile of the active medium, consistent with the increase of the gain factor in the axial region of GDT. The contraction is also imposed by HBr addition. Despite the fact that we used the external heating of GDT at the pump power of 1.5 kW and less, the energy input is still not sufficient to produce the effective generation for large active volume lasers; and it is evident from the small gain profile width. The maximum gain profile width under experimental conditions (consider Pout/ Pin > 2) was 3 cm; this value was obtained without HBr-additive within the active volume, while the concentration of CuBr vapors being significantly less than optimal, that corresponds to the maximum average lasing power.

  16. Spontaneous Neuronal Activity in Developing Neocortical Networks: From Single Cells to Large-Scale Interactions

    PubMed Central

    Luhmann, Heiko J.; Sinning, Anne; Yang, Jenq-Wei; Reyes-Puerta, Vicente; Stüttgen, Maik C.; Kirischuk, Sergei; Kilb, Werner

    2016-01-01

    Neuronal activity has been shown to be essential for the proper formation of neuronal circuits, affecting developmental processes like neurogenesis, migration, programmed cell death, cellular differentiation, formation of local and long-range axonal connections, synaptic plasticity or myelination. Accordingly, neocortical areas reveal distinct spontaneous and sensory-driven neuronal activity patterns already at early phases of development. At embryonic stages, when immature neurons start to develop voltage-dependent channels, spontaneous activity is highly synchronized within small neuronal networks and governed by electrical synaptic transmission. Subsequently, spontaneous activity patterns become more complex, involve larger networks and propagate over several neocortical areas. The developmental shift from local to large-scale network activity is accompanied by a gradual shift from electrical to chemical synaptic transmission with an initial excitatory action of chloride-gated channels activated by GABA, glycine and taurine. Transient neuronal populations in the subplate (SP) support temporary circuits that play an important role in tuning early neocortical activity and the formation of mature neuronal networks. Thus, early spontaneous activity patterns control the formation of developing networks in sensory cortices, and disturbances of these activity patterns may lead to long-lasting neuronal deficits. PMID:27252626

  17. A new robust adaptive controller for vibration control of active engine mount subjected to large uncertainties

    NASA Astrophysics Data System (ADS)

    Fakhari, Vahid; Choi, Seung-Bok; Cho, Chang-Hyun

    2015-04-01

    This work presents a new robust model reference adaptive control (MRAC) for vibration control caused from vehicle engine using an electromagnetic type of active engine mount. Vibration isolation performances of the active mount associated with the robust controller are evaluated in the presence of large uncertainties. As a first step, an active mount with linear solenoid actuator is prepared and its dynamic model is identified via experimental test. Subsequently, a new robust MRAC based on the gradient method with σ-modification is designed by selecting a proper reference model. In designing the robust adaptive control, structured (parametric) uncertainties in the stiffness of the passive part of the mount and in damping ratio of the active part of the mount are considered to investigate the robustness of the proposed controller. Experimental and simulation results are presented to evaluate performance focusing on the robustness behavior of the controller in the face of large uncertainties. The obtained results show that the proposed controller can sufficiently provide the robust vibration control performance even in the presence of large uncertainties showing an effective vibration isolation.

  18. Large-Scale Controls and Characteristics of Fire Activity in Central Chile, 2001-2015

    NASA Astrophysics Data System (ADS)

    McWethy, D. B.; Pauchard, A.; García, R.; Holz, A.; González, M.; Veblen, T. T.; Stahl, J.

    2016-12-01

    In recent decades, fire activity has increased in many ecosystems worldwide, even where fuel conditions and natural ignitions historically limited fire activity, and this increase begs questions of whether climate change, land-use change, and/or altered vegetation are responsible. Increased frequency of large fires in these settings has been attributed to drier-than-average summers and longer fire seasons as well as fuel accumulation related to ENSO events, raising concerns about the trajectory of post-fire vegetation dynamics and future fire regimes. In temperate and Mediterranean forests of central Chile, recent large fires associated with altered ecosystems, climate variability and land-use change highlight the risk and hazard of increasing fire activity yet the causes and consequences are poorly understood. To better understand characteristics of recent fire activity, key drivers of fire occurrence and the spatial probability of wildfire we examined the relationship between fire activity derived from MODIS satellite imagery and biophysical, land-cover and land-use variables. The probability of fire occurrence and annual area burned was best predicted by seasonal precipitation, annual temperature and land cover type. The likelihood of fire occurrence was greatest in Matorral shrublands, agricultural lands (including pasture lands) and Pinus and Eucalyptus plantations, highlighting the importance of vegetation type and fuel flammability as a critical control on fire activity. Our results suggest that land-use change responsible for the widespread presence of highly flammable vegetation and projections for continued warming and drying will likely combine to promote the occurrence of large fires in central Chile in the future.

  19. Activated adherent large granular lymphocytes/natural killer (LGL/NK) cells change their migratory behaviour.

    PubMed Central

    Pirelli, A; Allavena, P; Mantovani, A

    1988-01-01

    Unstimulated large granular lymphocytes/natural killer (LGL/NK) cells, unlike small T lymphocytes, exhibit prompt locomotion into nitrocellulose filters in response to chemo-attactrants, but, unlike monocytes, are unable to migrate as adherent cells across polycarbonate filters. Upon activation with 4-B-phorbol 12,13 dibutyrate (PDBU), LGL/NK cells become adherent and change their migratory behaviour, having the ability to migrate as adherent cells across polycarbonate filters. PDBU-treated high-density T lymphocytes did not show, under the same conditions, locomotory activity. The change in migratory behaviour following activation may represent an important determinant of the ability of activated LGL/NK cells to adhere to vascular linings and localize in tissues. PMID:3220508

  20. Function and regulation of large conductance Ca(2+)-activated K+ channel in vascular smooth muscle cells.

    PubMed

    Hu, Xiang-Qun; Zhang, Lubo

    2012-09-01

    Large conductance Ca(2+)-activated K(+) (BK(Ca)) channels are abundantly expressed in vascular smooth muscle cells. Activation of BK(Ca) channels leads to hyperpolarization of cell membrane, which in turn counteracts vasoconstriction. Therefore, BK(Ca) channels have an important role in regulation of vascular tone and blood pressure. The activity of BK(Ca) channels is subject to modulation by various factors. Furthermore, the function of BK(Ca) channels are altered in both physiological and pathophysiological conditions, such as pregnancy, hypertension and diabetes, which has dramatic impacts on vascular tone and hemodynamics. Consequently, compounds and genetic manipulation that alter activity and expression of the channel might be of therapeutic interest.

  1. Imaging large-scale cellular activity in spinal cord of freely behaving mice

    PubMed Central

    Sekiguchi, Kohei J.; Shekhtmeyster, Pavel; Merten, Katharina; Arena, Alexander; Cook, Daniela; Hoffman, Elizabeth; Ngo, Alexander; Nimmerjahn, Axel

    2016-01-01

    Sensory information from mechanoreceptors and nociceptors in the skin plays key roles in adaptive and protective motor behaviours. To date, very little is known about how this information is encoded by spinal cord cell types and their activity patterns, particularly under freely behaving conditions. To enable stable measurement of neuronal and glial cell activity in behaving mice, we have developed fluorescence imaging approaches based on two- and miniaturized one-photon microscopy. We show that distinct cutaneous stimuli activate overlapping ensembles of dorsal horn neurons, and that stimulus type and intensity is encoded at the single-cell level. In contrast, astrocytes show large-scale coordinated calcium responses to intense but not weak sensory inputs. Sensory-evoked activity is potently suppressed by anaesthesia. By revealing the cellular and computational logic of spinal cord networks under behaving conditions, our approach holds promise for better understanding of healthy and aberrant spinal cord processes. PMID:27121084

  2. Essential role of MALT1 protease activity in activated B cell-like diffuse large B-cell lymphoma.

    PubMed

    Hailfinger, Stephan; Lenz, Georg; Ngo, Vu; Posvitz-Fejfar, Anita; Rebeaud, Fabien; Guzzardi, Montserrat; Penas, Eva-Maria Murga; Dierlamm, Judith; Chan, Wing C; Staudt, Louis M; Thome, Margot

    2009-11-24

    A key element for the development of suitable anti-cancer drugs is the identification of cancer-specific enzymatic activities that can be therapeutically targeted. Mucosa-associated lymphoid tissue transformation protein 1 (MALT1) is a proto-oncogene that contributes to tumorigenesis in diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) subtype, the least curable subtype of DLBCL. Recent data suggest that MALT1 has proteolytic activity, but it is unknown whether this activity is relevant for tumor growth. Here we report that MALT1 is constitutively active in DLBCL lines of the ABC but not the GCB subtype. Inhibition of the MALT1 proteolytic activity led to reduced expression of growth factors and apoptosis inhibitors, and specifically affected the growth and survival of ABC DLBCL lines. These results demonstrate a key role for the proteolytic activity of MALT1 in DLBCL of the ABC subtype, and provide a rationale for the development of pharmacological inhibitors of MALT1 in DLBCL therapy.

  3. Optical activities of large-area SU8 microspirals fabricated by multibeam holographic lithography.

    PubMed

    Wang, Xia; Gao, Wensheng; Hung, Jenny; Tam, Wing Yim

    2014-04-10

    We report on the fabrication of large-area microspirals in SU8 photoresist using a 6+1 beam holographic lithography (HL) technique involving the interference of six linearly polarized side beams and one circularly polarized central beam. In contrast to common photoresist-substrate (glass) configuration, the spirals are fabricated on a substrate with a precured thin SU8 photoresist. This SU8-SU8-glass configuration strengthens the attachment of the spirals to the substrate, and hence enhances the quality of the fabricated spirals. The fabricated SU8 microspirals exhibit large optical activities with a polarization rotation close to 10 deg and a circular dichroism of about 0.5 in the visible range. Our precured substrate method could lift the limitations of the HL method in fabricating large and uniform microstructures or nanostructures.

  4. Miniature microscopes for large-scale imaging of neuronal activity in freely behaving rodents.

    PubMed

    Ziv, Yaniv; Ghosh, Kunal K

    2015-06-01

    Recording neuronal activity in behaving subjects has been instrumental in studying how information is represented and processed by the brain. Recent advances in optical imaging and bioengineering have converged to enable time-lapse, cell-type specific recordings of neuronal activities from large neuronal populations in deep-brain structures of freely behaving rodents. We will highlight these advancements, with an emphasis on miniaturized integrated microscopy for large-scale imaging in freely behaving mice. This technology potentially enables studies that were difficult to perform using previous generation imaging and current electrophysiological techniques. These studies include longitudinal and population-level analyses of neuronal representations associated with different types of naturalistic behaviors and cognitive or emotional processes.

  5. Assessment of Disease Activity in Large-vessel Vasculitis: Results of an International Delphi Exercise.

    PubMed

    Aydin, Sibel Z; Direskeneli, Haner; Merkel, Peter A

    2017-09-01

    To arrive at consensus for candidate outcomes for disease activity assessment in large-vessel vasculitis (LVV) in clinical trials. A Delphi survey including 99 items was circulated among international experts for 3 rounds. Fifty-seven items were accepted for both giant cell arteritis and Takayasu arteritis. Sixty-seven percent of experts voted to have a common approach for both diseases with additional disease-specific items such as weight loss, scalp tenderness/necrosis, morning stiffness, dizziness, visual symptoms, and imaging. This study highlights similarities and differences in experts' perspectives for assessing clinical activity in LVV and may guide a consensus-driven core set of validated outcomes.

  6. On the origin of large two-photon activity of DANS molecule.

    PubMed

    Alam, Md Mehboob; Chattopadhyaya, Mausumi; Chakrabarti, Swapan

    2012-11-15

    In this work, using the quadratic response theory and two-state model approach, we have explained the origin of high two-photon activity and the corresponding solvent dependence of 4,4'-dimethyl-amino-nitro-stilbene (DANS) molecule. For this purpose, we have made two structural modifications in the DANS molecule (1) at the donor-acceptor part and (2) at the unsaturated bridge between the two rings and calculated the one- and two-photon (OP and TP) absorption parameters of all the systems in gas phase and in three different solvents, viz., MeCN, THF, and toluene. We found that the removal of donor-acceptor groups from the original DANS molecule vanishes the transition moment between the ground and excited states and also the corresponding dipole moment difference, and the saturation of the π-conjugation bridge between the two rings keeping the donor-acceptor groups intact causes a large decrease in the ground to excited state transition moment. These changes, in turn, decrease the overall TP activity of the molecules as compared to DANS. On the basis of our analysis, we have concluded that neither the donor-acceptor pair nor the π-conjugation bridge between the two, rather their cooperative involvement leads to a large overlap between the ground and virtual and also the virtual and charge-transfer states, which are eventually responsible for the very large TP activity of DANS.

  7. CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-08-01

    Seizure activity is linked to astrocyte activation as well as dysfunctional cortical neuron excitability produced from changes in calcium-activated potassium (KCa) channel function. Ciliary neurotrophic factor-treated astrocyte conditioned medium (CNTF-ACM) can be used to investigate the peripheral effects of activated astrocytes upon cortical neurons. However, CNTF-ACM's effect upon KCa channel activity in cultured cortical neurons has not yet been investigated. Whole-cell patch clamp recordings were performed in rat cortical neurons to evaluate CNTF-ACM's effects upon charybdotoxin-sensitive large-conductance KCa (BK) channel currents and apamin-sensitive small-conductance KCa (SK) channel current. Biotinylation and RT-PCR were applied to assess CNTF-ACM's effects upon the protein and mRNA expression, respectively, of the SK channel subunits SK2 and SK3 and the BK channel subunits BKα1 and BKβ3. An anti-fibroblast growth factor-2 (FGF-2) monoclonal neutralizing antibody was used to assess the effects of the FGF-2 component of CNTF-ACM. CNTF-ACM significantly increased KCa channel current density, which was predominantly attributable to gains in BK channel activity (p < 0.05). CNTF-ACM produced a significant increase in BKα1 and BKβ3 expression (p < 0.05) but had no significant effect upon SK2 or SK3 expression (p > 0.05). Blocking FGF-2 produced significant reductions in KCa channel current density (p > 0.05) as well as BKα1 and BKβ3 expression in CNTF-ACM-treated neurons (p > 0.05). CNTF-ACM significantly enhances BK channel activity in rat cortical neurons and that FGF-2 is partially responsible for these effects. CNTF-induced astrocyte activation results in secretion of neuroactive factors which may affect neuronal excitability and resultant seizure activity in mammalian cortical neurons.

  8. How Gamification Affects Physical Activity: Large-scale Analysis of Walking Challenges in a Mobile Application

    PubMed Central

    Shameli, Ali; Althoff, Tim; Saberi, Amin; Leskovec, Jure

    2017-01-01

    Gamification represents an effective way to incentivize user behavior across a number of computing applications. However, despite the fact that physical activity is essential for a healthy lifestyle, surprisingly little is known about how gamification and in particular competitions shape human physical activity. Here we study how competitions affect physical activity. We focus on walking challenges in a mobile activity tracking application where multiple users compete over who takes the most steps over a predefined number of days. We synthesize our findings in a series of game and app design implications. In particular, we analyze nearly 2,500 physical activity competitions over a period of one year capturing more than 800,000 person days of activity tracking. We observe that during walking competitions, the average user increases physical activity by 23%. Furthermore, there are large increases in activity for both men and women across all ages, and weight status, and even for users that were previously fairly inactive. We also find that the composition of participants greatly affects the dynamics of the game. In particular, if highly unequal participants get matched to each other, then competition suffers and the overall effect on the physical activity drops significantly. Furthermore, competitions with an equal mix of both men and women are more effective in increasing the level of activities. We leverage these insights to develop a statistical model to predict whether or not a competition will be particularly engaging with significant accuracy. Our models can serve as a guideline to help design more engaging competitions that lead to most beneficial behavioral changes.

  9. Low Cost Hands-On Activities in Large Lecture Conceptual Physics Course

    NASA Astrophysics Data System (ADS)

    Dimiduk, Kathryn

    1998-10-01

    The student diversity in a university conceptual physic course presents a challenge to sustain the interest of all the students, to provide a solid conceptual basis for students continuing in science or engineering and to present science as an active subject rather than as vocabulary lists, rules and book knowledge. Combining ideas from the literature for teaching large lecture calculus based physics and science leary education majors in small class settings has resulted in a large (120 student) class format that mixes low cost (< $1,000 for term) hands-on activities, demonstrations, summary discussions and lectures. Hands-on activities are done in small groups which allows the diversity to become an asset. Several of these activities will be described in detail. The effectiveness of this teaching approach will be presented based on results of pre and post Force Concept Inventory test scores for this class and a comparison class that just used lecture and demonstrations for mechanics. The classes under comparison were taught by the same instructor, from the same book, were of similar size and neither had any additional teaching staff.

  10. CURRENT HELICITY OF ACTIVE REGIONS AS A TRACER OF LARGE-SCALE SOLAR MAGNETIC HELICITY

    SciTech Connect

    Zhang, H.; Gao, Y.; Xu, H.; Moss, D.; Kleeorin, N.; Rogachevskii, I.; Kuzanyan, K.; Sokoloff, D.

    2012-05-20

    We demonstrate that the current helicity observed in solar active regions traces the magnetic helicity of the large-scale dynamo generated field. We use an advanced two-dimensional mean-field dynamo model with dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic two-dimensional mean-field dynamo model with simple algebraic alpha-quenching only. Using these numerical models we obtained butterfly diagrams both for the small-scale current helicity and also for the large-scale magnetic helicity, and compared them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by -A {center_dot} B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are, respectively, the dynamo generated mean magnetic field and its vector potential. A theoretical interpretation of these results is given.

  11. Large Solar Energetic Particle Events Associated With Filament Eruptions Outside Active Regions

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-01-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds approx. 1000 km/s) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of approx.2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ?4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  12. Activation, Permeability, and Inhibition of Astrocytic and Neuronal Large Pore (Hemi)channels*♦

    PubMed Central

    Hansen, Daniel Bloch; Ye, Zu-Cheng; Calloe, Kirstine; Braunstein, Thomas Hartig; Hofgaard, Johannes Pauli; Ransom, Bruce R.; Nielsen, Morten Schak; MacAulay, Nanna

    2014-01-01

    Astrocytes and neurons express several large pore (hemi)channels that may open in response to various stimuli, allowing fluorescent dyes, ions, and cytoplasmic molecules such as ATP and glutamate to permeate. Several of these large pore (hemi)channels have similar characteristics with regard to activation, permeability, and inhibitor sensitivity. Consequently, their behaviors and roles in astrocytic and neuronal (patho)physiology remain undefined. We took advantage of the Xenopus laevis expression system to determine the individual characteristics of several large pore channels in isolation. Expression of connexins Cx26, Cx30, Cx36, or Cx43, the pannexins Px1 or Px2, or the purinergic receptor P2X7 yielded functional (hemi)channels with isoform-specific characteristics. Connexin hemichannels had distinct sensitivity to alterations of extracellular Ca2+ and their permeability to dyes and small atomic ions (conductance) were not proportional. Px1 and Px2 exhibited conductance at positive membrane potentials, but only Px1 displayed detectable fluorescent dye uptake. P2X7, in the absence of Px1, was permeable to fluorescent dyes in an agonist-dependent manner. The large pore channels displayed overlapping sensitivity to the inhibitors Brilliant Blue, gadolinium, and carbenoxolone. These results demonstrated isoform-specific characteristics among the large pore membrane channels; an open (hemi)channel is not a nonselective channel. With these isoform-specific properties in mind, we characterized the divalent cation-sensitive permeation pathway in primary cultured astrocytes. We observed no activation of membrane conductance or Cx43-mediated dye uptake in astrocytes nor in Cx43-expressing C6 cells. Our data underscore that although Cx43-mediated transport is observed in overexpressing cell systems, such transport may not be detectable in native cells under comparable experimental conditions. PMID:25086040

  13. Large Solar Energetic Particle Events Associated With Filament Eruptions Outside Active Regions

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-01-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds approx. 1000 km/s) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of approx.2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ?4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  14. Large scale tissue histopathology image classification, segmentation, and visualization via deep convolutional activation features.

    PubMed

    Xu, Yan; Jia, Zhipeng; Wang, Liang-Bo; Ai, Yuqing; Zhang, Fang; Lai, Maode; Chang, Eric I-Chao

    2017-05-26

    Histopathology image analysis is a gold standard for cancer recognition and diagnosis. Automatic analysis of histopathology images can help pathologists diagnose tumor and cancer subtypes, alleviating the workload of pathologists. There are two basic types of tasks in digital histopathology image analysis: image classification and image segmentation. Typical problems with histopathology images that hamper automatic analysis include complex clinical representations, limited quantities of training images in a dataset, and the extremely large size of singular images (usually up to gigapixels). The property of extremely large size for a single image also makes a histopathology image dataset be considered large-scale, even if the number of images in the dataset is limited. In this paper, we propose leveraging deep convolutional neural network (CNN) activation features to perform classification, segmentation and visualization in large-scale tissue histopathology images. Our framework transfers features extracted from CNNs trained by a large natural image database, ImageNet, to histopathology images. We also explore the characteristics of CNN features by visualizing the response of individual neuron components in the last hidden layer. Some of these characteristics reveal biological insights that have been verified by pathologists. According to our experiments, the framework proposed has shown state-of-the-art performance on a brain tumor dataset from the MICCAI 2014 Brain Tumor Digital Pathology Challenge and a colon cancer histopathology image dataset. The framework proposed is a simple, efficient and effective system for histopathology image automatic analysis. We successfully transfer ImageNet knowledge as deep convolutional activation features to the classification and segmentation of histopathology images with little training data. CNN features are significantly more powerful than expert-designed features.

  15. LARGE SOLAR ENERGETIC PARTICLE EVENTS ASSOCIATED WITH FILAMENT ERUPTIONS OUTSIDE ACTIVE REGIONS

    SciTech Connect

    Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-06-10

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ∼ 1000 km s{sup −1}) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2–3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ∼2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10–100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  16. Assessing Activity and Location of Individual Laying Hens in Large Groups Using Modern Technology

    PubMed Central

    Siegford, Janice M.; Berezowski, John; Biswas, Subir K.; Daigle, Courtney L.; Gebhardt-Henrich, Sabine G.; Hernandez, Carlos E.; Thurner, Stefan; Toscano, Michael J.

    2016-01-01

    Simple Summary Tracking of individual animals within large groups is increasingly possible offering an exciting opportunity to researchers. Whereas previously only relatively indistinguishable groups of individual animals could be observed and combined into pen level data, we can now focus on individual actors and track their activities across time and space with minimal intervention and disturbance. We describe several tracking systems that are currently in use for laying hens and review each, highlighting their strengths and weaknesses, as well as environments or conditions for which they may be most suited, and relevant issues to fit the best technology for the intended purpose. Abstract Tracking individual animals within large groups is increasingly possible, offering an exciting opportunity to researchers. Whereas previously only relatively indistinguishable groups of individual animals could be observed and combined into pen level data, we can now focus on individual actors within these large groups and track their activities across time and space with minimal intervention and disturbance. The development is particularly relevant to the poultry industry as, due to a shift away from battery cages, flock sizes are increasingly becoming larger and environments more complex. Many efforts have been made to track individual bird behavior and activity in large groups using a variety of methodologies with variable success. Of the technologies in use, each has associated benefits and detriments, which can make the approach more or less suitable for certain environments and experiments. Within this article, we have divided several tracking systems that are currently available into two major categories (radio frequency identification and radio signal strength) and review the strengths and weaknesses of each, as well as environments or conditions for which they may be most suitable. We also describe related topics including types of analysis for the data and concerns

  17. Large Scale Population Assessment of Physical Activity Using Wrist Worn Accelerometers: The UK Biobank Study

    PubMed Central

    Jackson, Dan; Hammerla, Nils; Granat, Malcolm H.; van Hees, Vincent T.; Trenell, Michael I.; Owen, Christoper G.; Preece, Stephen J.; Peakman, Tim; Brage, Soren

    2017-01-01

    Background Physical activity has not been objectively measured in prospective cohorts with sufficiently large numbers to reliably detect associations with multiple health outcomes. Technological advances now make this possible. We describe the methods used to collect and analyse accelerometer measured physical activity in over 100,000 participants of the UK Biobank study, and report variation by age, sex, day, time of day, and season. Methods Participants were approached by email to wear a wrist-worn accelerometer for seven days that was posted to them. Physical activity information was extracted from 100Hz raw triaxial acceleration data after calibration, removal of gravity and sensor noise, and identification of wear / non-wear episodes. We report age- and sex-specific wear-time compliance and accelerometer measured physical activity, overall and by hour-of-day, week-weekend day and season. Results 103,712 datasets were received (44.8% response), with a median wear-time of 6.9 days (IQR:6.5–7.0). 96,600 participants (93.3%) provided valid data for physical activity analyses. Vector magnitude, a proxy for overall physical activity, was 7.5% (2.35mg) lower per decade of age (Cohen’s d = 0.9). Women had a higher vector magnitude than men, apart from those aged 45-54yrs. There were major differences in vector magnitude by time of day (d = 0.66). Vector magnitude differences between week and weekend days (d = 0.12 for men, d = 0.09 for women) and between seasons (d = 0.27 for men, d = 0.15 for women) were small. Conclusions It is feasible to collect and analyse objective physical activity data in large studies. The summary measure of overall physical activity is lower in older participants and age-related differences in activity are most prominent in the afternoon and evening. This work lays the foundation for studies of physical activity and its health consequences. Our summary variables are part of the UK Biobank dataset and can be used by researchers as

  18. Large Scale Population Assessment of Physical Activity Using Wrist Worn Accelerometers: The UK Biobank Study.

    PubMed

    Doherty, Aiden; Jackson, Dan; Hammerla, Nils; Plötz, Thomas; Olivier, Patrick; Granat, Malcolm H; White, Tom; van Hees, Vincent T; Trenell, Michael I; Owen, Christoper G; Preece, Stephen J; Gillions, Rob; Sheard, Simon; Peakman, Tim; Brage, Soren; Wareham, Nicholas J

    2017-01-01

    Physical activity has not been objectively measured in prospective cohorts with sufficiently large numbers to reliably detect associations with multiple health outcomes. Technological advances now make this possible. We describe the methods used to collect and analyse accelerometer measured physical activity in over 100,000 participants of the UK Biobank study, and report variation by age, sex, day, time of day, and season. Participants were approached by email to wear a wrist-worn accelerometer for seven days that was posted to them. Physical activity information was extracted from 100Hz raw triaxial acceleration data after calibration, removal of gravity and sensor noise, and identification of wear / non-wear episodes. We report age- and sex-specific wear-time compliance and accelerometer measured physical activity, overall and by hour-of-day, week-weekend day and season. 103,712 datasets were received (44.8% response), with a median wear-time of 6.9 days (IQR:6.5-7.0). 96,600 participants (93.3%) provided valid data for physical activity analyses. Vector magnitude, a proxy for overall physical activity, was 7.5% (2.35mg) lower per decade of age (Cohen's d = 0.9). Women had a higher vector magnitude than men, apart from those aged 45-54yrs. There were major differences in vector magnitude by time of day (d = 0.66). Vector magnitude differences between week and weekend days (d = 0.12 for men, d = 0.09 for women) and between seasons (d = 0.27 for men, d = 0.15 for women) were small. It is feasible to collect and analyse objective physical activity data in large studies. The summary measure of overall physical activity is lower in older participants and age-related differences in activity are most prominent in the afternoon and evening. This work lays the foundation for studies of physical activity and its health consequences. Our summary variables are part of the UK Biobank dataset and can be used by researchers as exposures, confounding factors or outcome

  19. Muscle activation described with a differential equation model for large ensembles of locally coupled molecular motors.

    PubMed

    Walcott, Sam

    2014-10-01

    Molecular motors, by turning chemical energy into mechanical work, are responsible for active cellular processes. Often groups of these motors work together to perform their biological role. Motors in an ensemble are coupled and exhibit complex emergent behavior. Although large motor ensembles can be modeled with partial differential equations (PDEs) by assuming that molecules function independently of their neighbors, this assumption is violated when motors are coupled locally. It is therefore unclear how to describe the ensemble behavior of the locally coupled motors responsible for biological processes such as calcium-dependent skeletal muscle activation. Here we develop a theory to describe locally coupled motor ensembles and apply the theory to skeletal muscle activation. The central idea is that a muscle filament can be divided into two phases: an active and an inactive phase. Dynamic changes in the relative size of these phases are described by a set of linear ordinary differential equations (ODEs). As the dynamics of the active phase are described by PDEs, muscle activation is governed by a set of coupled ODEs and PDEs, building on previous PDE models. With comparison to Monte Carlo simulations, we demonstrate that the theory captures the behavior of locally coupled ensembles. The theory also plausibly describes and predicts muscle experiments from molecular to whole muscle scales, suggesting that a micro- to macroscale muscle model is within reach.

  20. Assessing Activity and Location of Individual Laying Hens in Large Groups Using Modern Technology.

    PubMed

    Siegford, Janice M; Berezowski, John; Biswas, Subir K; Daigle, Courtney L; Gebhardt-Henrich, Sabine G; Hernandez, Carlos E; Thurner, Stefan; Toscano, Michael J

    2016-02-02

    Tracking individual animals within large groups is increasingly possible, offering an exciting opportunity to researchers. Whereas previously only relatively indistinguishable groups of individual animals could be observed and combined into pen level data, we can now focus on individual actors within these large groups and track their activities across time and space with minimal intervention and disturbance. The development is particularly relevant to the poultry industry as, due to a shift away from battery cages, flock sizes are increasingly becoming larger and environments more complex. Many efforts have been made to track individual bird behavior and activity in large groups using a variety of methodologies with variable success. Of the technologies in use, each has associated benefits and detriments, which can make the approach more or less suitable for certain environments and experiments. Within this article, we have divided several tracking systems that are currently available into two major categories (radio frequency identification and radio signal strength) and review the strengths and weaknesses of each, as well as environments or conditions for which they may be most suitable. We also describe related topics including types of analysis for the data and concerns with selecting focal birds.

  1. Alternative Patterning Process for Realization of Large-Area, Full-Color, Active Quantum Dot Display.

    PubMed

    Park, Joon-Suh; Kyhm, Jihoon; Kim, Hong Hee; Jeong, Shinyoung; Kang, JoonHyun; Lee, Song-Ee; Lee, Kyu-Tae; Park, Kisun; Barange, Nilesh; Han, JiYeong; Song, Jin Dong; Choi, Won Kook; Han, Il Ki

    2016-11-09

    Although various colloidal quantum dot (QD) coating and patterning techniques have been developed to meet the demands in optoelectronic applications over the past years, each of the previously demonstrated methods has one or more limitations and trade-offs in forming multicolor, high-resolution, or large-area patterns of QDs. In this study, we present an alternative QD patterning technique using conventional photolithography combined with charge-assisted layer-by-layer (LbL) assembly to solve the trade-offs of the traditional patterning processes. From our demonstrations, we show repeatable QD patterning process that allows multicolor QD patterns in both large-area and microscale. Also, we show that the QD patterns are robust against additional photolithography processes and that the thickness of the QD patterns can be controlled at each position. To validate that this process can be applied to actual device applications as an active material, we have fabricated inverted, differently colored, active QD light-emitting device (QD-LED) on a pixelated substrate, which achieved maximum electroluminescence intensity of 23 770 cd/m(2), and discussed the results. From our findings, we believe that our process provides a solution to achieving both high-resolution and large-scale QD pattern applicable to not only display, but also to practical photonic device research and development.

  2. Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

    1999-01-01

    In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of

  3. Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

    1999-01-01

    In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of

  4. Activated charcoal alone or after gastric lavage: a simulated large paracetamol intoxication

    PubMed Central

    Christophersen, A B; Levin, D; Hoegberg, L C G; Angelo, H R; Kampmann, J P

    2002-01-01

    administered 2 h after tablet ingestion when compared with controls (median 22.7%, 95% confidence intervals 13.6–34.4). Conclusions These results suggest that combination treatment may be no better than activated charcoal alone in patients presenting early after large overdoses. The effect of activated charcoal given 2 h post ingestion is substantially less than at 1 h, emphasizing the importance of early intervention. PMID:11874395

  5. Patterns of Activity in the Human Frontal and Parietal Cortex Differentiate Large and Small Saccades

    PubMed Central

    Grosbras, Marie-Hélène

    2016-01-01

    A vast literature indicates that small and large saccades, respectively, subserve different perceptual and cognitive strategies and may rely on different programming modes. While it is well-established that in monkeys’ main oculomotor brain regions small and large eye movements are controlled by segregated neuronal populations, the representation of saccade amplitude in the human brain remains unclear. To address this question we used functional magnetic resonance imaging to scan participants while they performed saccades toward targets at either short (4°) or large (30°) eccentricity. A regional multivoxel pattern analysis reveals that patterns of activity in the frontal eye-field and parietal eye fields discriminate between the execution of large or small saccades. This was not the case in the supplementary eye-fields nor in the inferior precentral cortex. These findings provide the first evidence of a representation of saccadic eye movement size in the fronto-parietal occulomotor circuit. They shed light on the respective roles of the different cortical oculomotor regions with respect to space perception and exploration, as well as on the homology of eye movement control between human and non-human primates. PMID:27833536

  6. Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device

    SciTech Connect

    Agostinetti, P.; Antoni, V.; Chitarin, G.; Pilan, N.; Serianni, G.; Veltri, P.; Cavenago, M.; Nakano, H.; Takeiri, Y.; Tsumori, K.

    2011-09-26

    At the National Institute for Fusion Science (NIFS) large-scaled negative ion sources have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device (LHD), which is the world-largest superconducting helical system. These injectors have achieved outstanding performances in terms of beam energy, negative-ion current and optics, and represent a reference for the development of heating and current drive NBIs for ITER.In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral Beam system (MITICA) is under construction at Consorzio RFX in Padova.An experimental validation of the codes has been undertaken in order to prove the accuracy of the simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS, with the goal of comparing and benchmarking the codes with the experimental data. A description of these modeling activities and a discussion of the main results obtained are reported in this paper.

  7. Evaluation of a large capacity heat pump concept for active cooling of hypersonic aircraft structure

    NASA Technical Reports Server (NTRS)

    Pagel, L. L.; Herring, R. L.

    1978-01-01

    Results of engineering analyses assessing the conceptual feasibility of a large capacity heat pump for enhancing active cooling of hypersonic aircraft structure are presented. A unique heat pump arrangement which permits cooling the structure of a Mach 6 transport to aluminum temperatures without the aid of thermal shielding is described. The selected concept is compatible with the use of conventional refrigerants, with Freon R-11 selected as the preferred refrigerant. Condenser temperatures were limited to levels compatible with the use of conventional refrigerants by incorporating a unique multipass condenser design, which extracts mechanical energy from the hydrogen fuel, prior to each subsequent pass through the condenser. Results show that it is technically feasible to use a large capacity heat pump in lieu of external shielding. Additional analyses are required to optimally apply this concept.

  8. Large-scale production and properties of human plasma-derived activated Factor VII concentrate.

    PubMed

    Tomokiyo, K; Yano, H; Imamura, M; Nakano, Y; Nakagaki, T; Ogata, Y; Terano, T; Miyamoto, S; Funatsu, A

    2003-01-01

    An activated Factor VII (FVIIa) concentrate, prepared from human plasma on a large scale, has to date not been available for clinical use for haemophiliacs with antibodies against FVIII and FIX. In the present study, we attempted to establish a large-scale manufacturing process to obtain plasma-derived FVIIa concentrate with high recovery and safety, and to characterize its biochemical and biological properties. FVII was purified from human cryoprecipitate-poor plasma, by a combination of anion exchange and immunoaffinity chromatography, using Ca2+-dependent anti-FVII monoclonal antibody. To activate FVII, a FVII preparation that was nanofiltered using a Bemberg Microporous Membrane-15 nm was partially converted to FVIIa by autoactivation on an anion-exchange resin. The residual FVII in the FVII and FVIIa mixture was completely activated by further incubating the mixture in the presence of Ca2+ for 18 h at 10 degrees C, without any additional activators. For preparation of the FVIIa concentrate, after dialysis of FVIIa against 20 mm citrate, pH 6.9, containing 13 mm glycine and 240 mm NaCl, the FVIIa preparation was supplemented with 2.5% human albumin (which was first pasteurized at 60 degrees C for 10 h) and lyophilized in vials. To inactivate viruses contaminating the FVIIa concentrate, the lyophilized product was further heated at 65 degrees C for 96 h in a water bath. Total recovery of FVII from 15 000 l of plasma was approximately 40%, and the FVII preparation was fully converted to FVIIa with trace amounts of degraded products (FVIIabeta and FVIIagamma). The specific activity of the FVIIa was approximately 40 U/ micro g. Furthermore, virus-spiking tests demonstrated that immunoaffinity chromatography, nanofiltration and dry-heating effectively removed and inactivated the spiked viruses in the FVIIa. These results indicated that the FVIIa concentrate had both high specific activity and safety. We established a large-scale manufacturing process of human plasma

  9. The conserved core enzymatic activities and the distinct dynamics of polyomavirus large T antigens

    PubMed Central

    An, Ping; Brodsky, Jeffrey L.; Pipas, James M.

    2016-01-01

    Several human polyomaviruses including JCV, BKV and TSV are associated with diseases, particularly in immunosuppressed patients. While the large T antigen (LT) encoded by the monkey polyomavirus SV40 is well studied, and possesses intrinsic ATPase and DNA helicase activities, the LTs of the human polyomaviruses are relatively uncharacterized. In order to evaluate whether these enzymatic activities, which are required for viral DNA replication, are conserved between polyomaviruses, we performed a comparative study using the LTs from JCV, TSV and SV40. The ATPase and DNA helicase activities and the interaction with the cellular tumor suppressor p53 were assayed for the purified Zn-ATPase domains of the three LTs. We found that all Zn-ATPases were active ATPases. The Zn-ATPase domains also functioned as DNA helicases, although the measured kinetic constants differed among the three proteins. In addition, when tested against four small molecule ATPase inhibitors, the Zn-ATPase domains of TSV was more resistant than that of SV40 and JCV. Our results show that, while LTs from JCV and TSV share the core ATPase and DNA helicase activities, they possess important functional differences that might translate into their respective abilities to infect and replicate in hosts. PMID:25752954

  10. Introductory biology courses: a framework to support active learning in large enrollment introductory science courses.

    PubMed

    Smith, Ann C; Stewart, Richard; Shields, Patricia; Hayes-Klosteridis, Jennifer; Robinson, Paulette; Yuan, Robert

    2005-01-01

    Active learning and research-oriented activities have been increasingly used in smaller, specialized science courses. Application of this type of scientific teaching to large enrollment introductory courses has been, however, a major challenge. The general microbiology lecture/laboratory course described has been designed to incorporate published active-learning methods. Three major case studies are used as platforms for active learning. Themes from case studies are integrated into lectures and laboratory experiments, and in class and online discussions and assignments. Students are stimulated to apply facts to problem-solving and to learn research skills such as data analysis, writing, and working in teams. This course is feasible only because of its organizational framework that makes use of teaching teams (made up of faculty, graduate assistants, and undergraduate assistants) and Web-based technology. Technology is a mode of communication, but also a system of course management. The relevance of this model to other biology courses led to assessment and evaluation, including an analysis of student responses to the new course, class performance, a university course evaluation, and retention of course learning. The results are indicative of an increase in student engagement in research-oriented activities and an appreciation of real-world context by students.

  11. Introductory Biology Courses: A Framework To Support Active Learning in Large Enrollment Introductory Science Courses

    PubMed Central

    2005-01-01

    Active learning and research-oriented activities have been increasingly used in smaller, specialized science courses. Application of this type of scientific teaching to large enrollment introductory courses has been, however, a major challenge. The general microbiology lecture/laboratory course described has been designed to incorporate published active-learning methods. Three major case studies are used as platforms for active learning. Themes from case studies are integrated into lectures and laboratory experiments, and in class and online discussions and assignments. Students are stimulated to apply facts to problem-solving and to learn research skills such as data analysis, writing, and working in teams. This course is feasible only because of its organizational framework that makes use of teaching teams (made up of faculty, graduate assistants, and undergraduate assistants) and Web-based technology. Technology is a mode of communication, but also a system of course management. The relevance of this model to other biology courses led to assessment and evaluation, including an analysis of student responses to the new course, class performance, a university course evaluation, and retention of course learning. The results are indicative of an increase in student engagement in research-oriented activities and an appreciation of real-world context by students. PMID:15917873

  12. A single intratumoral injection of a fiber-mutant adenoviral vector encoding interleukin 12 induces remarkable anti-tumor and anti-metastatic activity in mice with Meth-A fibrosarcoma.

    PubMed

    Gao, Jian-Qing; Sugita, Toshiki; Kanagawa, Naoko; Iida, Keisuke; Eto, Yusuke; Motomura, Yoshiaki; Mizuguchi, Hiroyuki; Tsutsumi, Yasuo; Hayakawa, Takao; Mayumi, Tadanori; Nakagawa, Shinsaku

    2005-03-25

    Cytokine-encoding viral vectors are considered to be promising in cancer gene immunotherapy. Interleukin 12 (IL-12) has been used widely for anti-tumor treatment, but the administration route and tumor characteristics strongly influence therapeutic efficiency. Meth-A fibrosarcoma has been demonstrated to be insensitive to IL-12 treatment via systemic administration. In the present study, we developed an IL-12-encoding fiber-mutant adenoviral vector (AdRGD-IL-12) that showed enhanced gene transfection efficiency in Meth-A tumor cells, and the production of IL-12 p70 in the culture supernatant from transfected cells was confirmed by ELISA. In therapeutic experiments, a single low-dose (2 x 10(7) plaque-forming units) intratumoral injection of AdRGD-IL-12 elicited pronounced anti-tumor activity and notably prolonged the survival of Meth-A fibrosarcoma-bearing mice. Immunohistochemical staining revealed that the IL-12 vector induced the accumulation of T cells in tumor tissue. Furthermore, intratumoral administration of the vector induced an anti-metastasis effect as well as long-term specific immunity against syngeneic tumor challenge.

  13. Structural basis for the superior activity of the large isoform of snow flea antifreeze protein.

    PubMed

    Mok, Yee-Foong; Lin, Feng-Hsu; Graham, Laurie A; Celik, Yeliz; Braslavsky, Ido; Davies, Peter L

    2010-03-23

    The snow flea (Hypogastrum harveyi) is protected from freezing at sub-zero temperatures by a glycine-rich antifreeze protein (AFP) that binds to seed ice crystals and prevents them from growing larger. This AFP is hyperactive and comprises two isoforms [Graham, L. A., and Davies, P. L. (2005) Science 310, 461]. The larger isoform (15.7 kDa) exhibits several-fold higher activity than the smaller isoform (6.5 kDa), although it is considerably less abundant. To establish the molecular basis for this difference in activity, we determined the sequence of the large isoform. The primary sequences of these two isoforms are surprisingly divergent. However, both contain tripeptide repeats and turn motifs that enabled us to build a three-dimensional model of the large isoform based upon the six-polyproline helix structure of the small isoform. Our model contains 13 polyproline type II helices connected by proline-containing loops stacked into two flat sheets oriented antiparallel to one another. The structure is strictly amphipathic, with a hydrophilic surface on one side and a hydrophobic, putative ice-binding surface on the other. The putative ice-binding site is approximately twice as large in area as that of the small isoform, providing an explanation for the difference in activity that is consistent with other examples noted. By tagging the recombinant AFP with green fluorescent protein, we observed its binding to multiple planes of ice, especially the basal plane. This finding supports the correlation between AFP hyperactivity and basal plane binding first observed with spruce budworm AFP.

  14. Recent advances toward a fiber optic sensor for nerve agent

    NASA Astrophysics Data System (ADS)

    Beshay, Manal; Cordero, Steven R.; Mukamal, Harold; Ruiz, David; Lieberman, Robert A.

    2008-04-01

    We report advances made on the development of a fiber optic nerve agent sensor having its entire length as the sensing element. Upon exposure to sarin gas or its simulant, diisopropyl fluorophosphate, the cladding changes color resulting in an alteration of the light intensity throughput. The optical fiber is multimode and consists of a fused-silica core and a nerve agent sensitive cladding. The absorption characteristics of the cladding affect the fiber's spectral attenuation and limit the length of light guiding fiber that can be deployed continuously. The absorption of the cladding is also dependent on the sensor formulation, which in turn influences the sensitivity of the fiber. In this paper, data related to the trade-off of sensitivity, spectral attenuation, and length of fiber challenged will be reported. The fiber is mass produced using a conventional fiber optic draw tower. This technology could be used to protect human resources and buildings from dangerous chemical attacks, particularly when large areas or perimeters must be covered. It may also be used passively to determine how well such areas have been decontaminated.

  15. Resveratrol attenuates cortical neuron activity: roles of large conductance calcium-activated potassium channels and voltage-gated sodium channels.

    PubMed

    Wang, Ya-Jean; Chan, Ming-Huan; Chen, Linyi; Wu, Sheng-Nan; Chen, Hwei-Hisen

    2016-05-21

    Resveratrol, a phytoalexin found in grapes and red wine, exhibits diverse pharmacological activities. However, relatively little is known about whether resveratrol modulates the ion channels in cortical neurons. The large-conductance calcium-activated potassium channels (BKCa) and voltage-gated sodium channels were expressed in cortical neurons and play important roles in regulation of neuronal excitability. The present study aimed to determine the effects of resveratrol on BKCa currents and voltage-gated sodium currents in cortical neurons. Resveratrol concentration-dependently increased the current amplitude and the opening activity of BKCa channels, but suppressed the amplitude of voltage-gated sodium currents. Similar to the BKCa channel opener NS1619, resveratrol decreased the firing rate of action potentials. In addition, the enhancing effects of BKCa channel blockers tetraethylammonium (TEA) and paxilline on action potential firing were sensitive to resveratrol. Our results indicated that the attenuation of action potential firing rate by resveratrol might be mediated through opening the BKCa channels and closing the voltage-gated sodium channels. As BKCa channels and sodium channels are critical molecular determinants for seizure generation, our findings suggest that regulation of these two channels in cortical neurons probably makes a considerable contribution to the antiseizure activity of resveratrol.

  16. Systematic detection of seismic activity before recent large earthquakes in China

    NASA Astrophysics Data System (ADS)

    Peng, Z.; Wang, B.; Ruan, X.; Meng, X.; Hongwei, T.; Long, F.; Su, J.

    2014-12-01

    Sometimes large shallow earthquakes are preceded by increased local seismic activity, known as "foreshocks". However, the exact relationship between foreshocks and mainshock nucleation is still in debate. Several studies have found accelerating or migrating foreshock activity right before recent large earthquakes along major plate boundary faults, indicating that foreshocks are likely driven by slow-slip events. However, it is still not
clear whether similar features could be observed for earthquakes that occur away from plate-boundary regions.
Here we conduct a systematic detection of possible foreshock activity around the times of 6 recent large earthquakes in China.
The candidate events include the 2008 Ms7.3 Yutian, Ms8.0 Wenchuan, the 2010 Ms7.0 Yushu,
the 2013 Ms7.0 Lushan, the 2014 Ms7.3 Yutian, and the 2014 Ms6.5 Zhaotong earthquakes. Among them, the 2010 Yushu and 2014 Yutian mainshocks had clear evidence of M4-5 immediate foreshocks listed in regional earthquake catalogs, while the rest
did not. In each case, we use waveforms of local earthquakes listed in the catalog as templates and scan through continuous waveforms recorded by both permanent and temporary seismic stations around the epicentral region of each mainshock. Our waveform matching method can detect at least a few times more events than listed in the catalog. Our initial results show a wide range of behaviors. For the 2010 Yushu and 2014 Yutian cases, the M4-5 foreshocks were followed by many smaller-size events that could be considered as their aftershocks. For the Wenchuan case, we did not observe any obvious foreshock in the immediate vicinity of the epicenter. However, we found one swarm sequence that shows systematic migration a few months before the Wenchuan mainshock. Our next step is to relocate these newly detected events to search for spatio-temporal evolutions before each mainshock, as well
as performing Epidemic Type Aftershock Sequence (ETAS) modeling to examine

  17. Conceiving semi-active control devices for large-size monolithic monuments

    NASA Astrophysics Data System (ADS)

    Casciati, Fabio; El Attar, Adel; Casciati, Sara

    2001-07-01

    CHIME is a research project, funded by the European Union, which investigates the adoption of innovative structural control techniques in view of the seismic rehabilitation of the wide monumental cultural heritage in Mediterranean countries as Egypt, Tunisia and Cyprus. The structural control devices are mainly of the semi-active type. In this particular paper one reports the first results achieved within a case study. It considers an Egyptian large size monolithic monument. Alternative solutions for its seismic rehabilitation are eventually conceived and discussed.

  18. Using a fiber loop and fiber bragg grating as a fiber optic sensor to simultaneously measure temperature and displacement.

    PubMed

    Chang, Yao-Tang; Yen, Chih-Ta; Wu, Yue-Shiun; Cheng, Hsu-Chih

    2013-05-16

    This study integrated a fiber loop manufactured by using commercial fiber (SMF-28, Corning) and a fiber Bragg grating (FBG) to form a fiber optic sensor that could simultaneously measure displacement and temperature. The fiber loop was placed in a thermoelectric cooling module with FBG affixed to the module, and, consequently, the center wavelength displacement of FBG was limited by only the effects of temperature change. Displacement and temperature were determined by measuring changes in the transmission of optical power and shifts in Bragg wavelength. This study provides a simple and economical method to measure displacement and temperature simultaneously.

  19. Large contribution of sea surface warming to recent increase in Atlantic hurricane activity.

    PubMed

    Saunders, Mark A; Lea, Adam S

    2008-01-31

    Atlantic hurricane activity has increased significantly since 1995 (refs 1-4), but the underlying causes of this increase remain uncertain. It is widely thought that rising Atlantic sea surface temperatures have had a role in this, but the magnitude of this contribution is not known. Here we quantify this contribution for storms that formed in the tropical North Atlantic, Caribbean Sea and Gulf of Mexico; these regions together account for most of the hurricanes that make landfall in the United States. We show that a statistical model based on two environmental variables--local sea surface temperature and an atmospheric wind field--can replicate a large proportion of the variance in tropical Atlantic hurricane frequency and activity between 1965 and 2005. We then remove the influence of the atmospheric wind field to assess the contribution of sea surface temperature. Our results indicate that the sensitivity of tropical Atlantic hurricane activity to August-September sea surface temperature over the period we consider is such that a 0.5 degrees C increase in sea surface temperature is associated with a approximately 40% increase in hurricane frequency and activity. The results also indicate that local sea surface warming was responsible for approximately 40% of the increase in hurricane activity relative to the 1950-2000 average between 1996 and 2005. Our analysis does not identify whether warming induced by greenhouse gases contributed to the increase in hurricane activity, but the ability of climate models to reproduce the observed relationship between hurricanes and sea surface temperature will serve as a useful means of assessing whether they are likely to provide reliable projections of future changes in Atlantic hurricane activity.

  20. Investigating Informatics Activity, Control, and Training Needs in Large, Medium, and Small Health Departments.

    PubMed

    Bakota, Eric; Arnold, Ryan; Yang, Biru

    2016-01-01

    A recent National Association of City & County Health Officials survey shed light on informatics workforce development needs. Local health departments (LHDs) of various jurisdictional sizes and control over informatics may differ on training needs and activity. Understanding the precise nature of this variation will allow stakeholders to appropriately develop workforce development tools to advance the field. To understand the informatics training needs for LHDs of different jurisdictional sizes. Survey responses were analyzed by comparing training needs and LHD population size. Larger health departments consistently reported having greater informatics-related capacity and informatics-related training needs. Quantitative data analysis was identified as a primary need for large LHDs. In addition, LHDs that report higher control of informatics/information technology were able to engage in more informatics activities. Smaller LHDs need additional resources to improve informatics-related capacity and engagement with the field.

  1. Molecular heterogeneity of large-conductance calcium-activated potassium channels in canine intracardiac ganglia.

    PubMed

    Selga, Elisabet; Pérez-Serra, Alexandra; Moreno-Asso, Alba; Anderson, Seth; Thomas, Kristen; Desai, Mayurika; Brugada, Ramon; Pérez, Guillermo J; Scornik, Fabiana S

    2013-01-01

    Large conductance calcium-activated potassium (BK) channels are widely expressed in the nervous system. We have recently shown that principal neurons from canine intracardiac ganglia (ICG) express a paxilline- and TEA-sensitive BK current, which increases neuronal excitability. In the present work, we further explore the molecular constituents of the BK current in canine ICG. We found that the β1 and β4 regulatory subunits are expressed in ICG. Single channel voltage-dependence at different calcium concentrations suggested that association of the BKα with a particular β subunit was not enough to explain the channel activity in this tissue. Indeed, we detected the presence of several splice variants of the BKα subunit. In conclusion, BK channels in canine ICG may result from the arrangement of different BKα splice variants, plus accessory β subunits. The particular combinations expressed in canine IC neurons likely rule the excitatory role of BK current in this tissue.

  2. Investigating Informatics Activity, Control, and Training Needs in Large, Medium, and Small Health Departments

    PubMed Central

    Arnold, Ryan; Yang, Biru

    2016-01-01

    Introduction: A recent National Association of City & County Health Officials survey shed light on informatics workforce development needs. Local health departments (LHDs) of various jurisdictional sizes and control over informatics may differ on training needs and activity. Understanding the precise nature of this variation will allow stakeholders to appropriately develop workforce development tools to advance the field. Objective: To understand the informatics training needs for LHDs of different jurisdictional sizes. Methods: Survey responses were analyzed by comparing training needs and LHD population size. Results: Larger health departments consistently reported having greater informatics-related capacity and informatics-related training needs. Quantitative data analysis was identified as a primary need for large LHDs. In addition, LHDs that report higher control of informatics/information technology were able to engage in more informatics activities. Conclusion: Smaller LHDs need additional resources to improve informatics-related capacity and engagement with the field. PMID:27684621

  3. Large-scale isolation and cytotoxicity of extracellular vesicles derived from activated human natural killer cells

    PubMed Central

    Jong, Ambrose Y.; Wu, Chun-Hua; Li, Jingbo; Sun, Jianping; Fabbri, Muller; Wayne, Alan S.; Seeger, Robert C.

    2017-01-01

    ABSTRACT Extracellular vesicles (EVs) have been the focus of great interest, as they appear to be involved in numerous important cellular processes. They deliver bioactive macromolecules such as proteins, lipids, and nucleic acids, allowing intercellular communication in multicellular organisms. EVs are secreted by all cell types, including immune cells such as natural killer cells (NK), and they may play important roles in the immune system. Currently, a large-scale procedure to obtain functional NK EVs is lacking, limiting their use clinically. In this report, we present a simple, robust, and cost-effective method to isolate a large quantity of NK EVs. After propagating and activating NK cells ex vivo and then incubating them in exosome-free medium for 48 h, EVs were isolated using a polymer precipitation method. The isolated vesicles contain the tetraspanin CD63, an EV marker, and associated proteins (fibronectin), but are devoid of cytochrome C, a cytoplasmic marker. Nanoparticle tracking analysis showed a size distribution between 100 and 200 nm while transmission electron microscopy imaging displayed vesicles with an oval shape and comparable sizes, fulfilling the definition of EV. Importantly, isolated EV fractions were cytotoxic against cancer cells. Furthermore, our results demonstrate for the first time that isolated activated NK (aNK) cell EVs contain the cytotoxic proteins perforin, granulysin, and granzymes A and B, incorporated from the aNK cells. Activation of caspase -3, -7 and -9 was detected in cancer cells incubated with aNK EVs, and caspase inhibitors blocked aNK EV-induced cytotoxicity, suggesting that aNK EVs activate caspase pathways in target cells. The ability to isolate functional aNK EVs on a large scale may lead to new clinical applications. Abbreviations: NK: natural killer cells; activated NK (aNK) cells; EVs: extracellular vesicles; ALL: acute lymphoblastic leukaemia; aAPC: artificial antigen-presenting cell; TEM: transmission

  4. Photoacoustic wave detection on water using a fiber optic transducer

    NASA Astrophysics Data System (ADS)

    Montoya, Jose P.; Munera, Natalia; Acuna-Herrera, Rodrigo

    2016-09-01

    In this work, a fiber optic microphone system was built and tested. The purpose of the fiber microphone is to sense photoacoustic waves produced by water molecules excited by an ultrafast laser. The use of a fiber sensor allows for ease of three-dimension measurement implementation for a 3-D imaging based on water amounts of different materials, this sensor can be directly submerged in water or a phantom gel without electromagnetic interference nor corrosion.

  5. Seasonal prediction of lightning activity in North Western Venezuela: Large-scale versus local drivers

    NASA Astrophysics Data System (ADS)

    Muñoz, Á. G.; Díaz-Lobatón, J.; Chourio, X.; Stock, M. J.

    2016-05-01

    The Lake Maracaibo Basin in North Western Venezuela has the highest annual lightning rate of any place in the world (~ 200 fl km- 2 yr- 1), whose electrical discharges occasionally impact human and animal lives (e.g., cattle) and frequently affect economic activities like oil and natural gas exploitation. Lightning activity is so common in this region that it has a proper name: Catatumbo Lightning (plural). Although short-term lightning forecasts are now common in different parts of the world, to the best of the authors' knowledge, seasonal prediction of lightning activity is still non-existent. This research discusses the relative role of both large-scale and local climate drivers as modulators of lightning activity in the region, and presents a formal predictability study at seasonal scale. Analysis of the Catatumbo Lightning Regional Mode, defined in terms of the second Empirical Orthogonal Function of monthly Lightning Imaging Sensor (LIS-TRMM) and Optical Transient Detector (OTD) satellite data for North Western South America, permits the identification of potential predictors at seasonal scale via a Canonical Correlation Analysis. Lightning activity in North Western Venezuela responds to well defined sea-surface temperature patterns (e.g., El Niño-Southern Oscillation, Atlantic Meridional Mode) and changes in the low-level meridional wind field that are associated with the Inter-Tropical Convergence Zone migrations, the Caribbean Low Level Jet and tropical cyclone activity, but it is also linked to local drivers like convection triggered by the topographic configuration and the effect of the Maracaibo Basin Nocturnal Low Level Jet. The analysis indicates that at seasonal scale the relative contribution of the large-scale drivers is more important than the local (basin-wide) ones, due to the synoptic control imposed by the former. Furthermore, meridional CAPE transport at 925 mb is identified as the best potential predictor for lightning activity in the Lake

  6. Macro optical projection tomography for large scale 3D imaging of plant structures and gene activity

    PubMed Central

    Lee, Karen J. I.; Calder, Grant M.; Hindle, Christopher R.; Newman, Jacob L.; Robinson, Simon N.; Avondo, Jerome J. H. Y.

    2017-01-01

    Abstract Optical projection tomography (OPT) is a well-established method for visualising gene activity in plants and animals. However, a limitation of conventional OPT is that the specimen upper size limit precludes its application to larger structures. To address this problem we constructed a macro version called Macro OPT (M-OPT). We apply M-OPT to 3D live imaging of gene activity in growing whole plants and to visualise structural morphology in large optically cleared plant and insect specimens up to 60 mm tall and 45 mm deep. We also show how M-OPT can be used to image gene expression domains in 3D within fixed tissue and to visualise gene activity in 3D in clones of growing young whole Arabidopsis plants. A further application of M-OPT is to visualise plant-insect interactions. Thus M-OPT provides an effective 3D imaging platform that allows the study of gene activity, internal plant structures and plant-insect interactions at a macroscopic scale. PMID:28025317

  7. Methylseleninic acid inhibits HDAC activity in diffuse large B-cell lymphoma cell lines.

    PubMed

    Kassam, Shireen; Goenaga-Infante, Heidi; Maharaj, Lenushka; Hiley, Crispin T; Juliger, Simone; Joel, Simon P

    2011-09-01

    Selenium is a trace element that is fundamental to human health. Research has mainly focussed on its role in cancer prevention, but recent evidence supports its role in established cancer, with high concentrations inducing tumour cell death and non-toxic concentrations sensitising cells to chemotherapy. However, the precise mechanism of selenium action is not clear. The effect of methylseleninic acid (MSA), an organic selenium compound, on histone deacetylase (HDAC) activity in diffuse large B-cell lymphoma cell lines is reported here. Lymphoma cell lines were exposed to MSA under normoxic and hypoxic conditions. Protein expression was determined by western blotting, HDAC activity and VEGF concentration by fluorimetric and electrochemiluminescence assays, respectively, and intracellular selenium metabolites quantified by mass spectrometry. MSA inhibited HDAC activity, which resulted in the acetylation of histone H3 and α-tubulin. However, cellular metabolism of MSA to methylselenol was required for this effect. Dimethylselenide, the methylation product of methylselenol, was found to be the major intracellular metabolite. MSA also inhibited HIF-1α expression and VEGF secretion, a possible consequence of HDAC inhibition. The ability of methylselenol to inhibit HDAC activity has not been previously reported, thus providing a novel mechanism of selenium action.

  8. Macro optical projection tomography for large scale 3D imaging of plant structures and gene activity.

    PubMed

    Lee, Karen J I; Calder, Grant M; Hindle, Christopher R; Newman, Jacob L; Robinson, Simon N; Avondo, Jerome J H Y; Coen, Enrico S

    2016-12-26

    Optical projection tomography (OPT) is a well-established method for visualising gene activity in plants and animals. However, a limitation of conventional OPT is that the specimen upper size limit precludes its application to larger structures. To address this problem we constructed a macro version called Macro OPT (M-OPT). We apply M-OPT to 3D live imaging of gene activity in growing whole plants and to visualise structural morphology in large optically cleared plant and insect specimens up to 60 mm tall and 45 mm deep. We also show how M-OPT can be used to image gene expression domains in 3D within fixed tissue and to visualise gene activity in 3D in clones of growing young whole Arabidopsis plants. A further application of M-OPT is to visualise plant-insect interactions. Thus M-OPT provides an effective 3D imaging platform that allows the study of gene activity, internal plant structures and plant-insect interactions at a macroscopic scale.

  9. Large-scale pattern formation in active particles suspensions: from interacting microtubules to swimming bacteria

    NASA Astrophysics Data System (ADS)

    Aranson, Igor

    2006-03-01

    We consider two biological systems of active particles exhibiting large-scale collective behavior: microtubules interacting with molecular motors and hydrodynamically entrained swimming bacteria. Starting from a generic stochastic microscopic model of inelastically colliding polar rods with an anisotropic interaction kernel, we derive set of equations for the local rods concentration and orientation. Above certain critical density of rods the model exhibits orientational instability and onset of large-scale coherence. For the microtubules and molecular motors system we demonstrate that the orientational instability leads to the formation of vortices and asters seen in recent experiments. Similar approach is applied to colonies of swimming bacteria Bacillus subtilis confined in thin fluid film. The model is formulated in term of two-dimensional equations for local density and orientation of bacteria coupled to the low Reynolds number Navier-Stokes equation for the fluid flow velocity. The collective swimming of bacteria is represented by additional source term in the Navier-Stokes equation. We demonstrate that this system exhibits formation of dynamic large-scale patterns with the typical scale determined by the density of bacteria.

  10. Large-activation-energy analysis of gaseous reactive flow in pipes

    NASA Astrophysics Data System (ADS)

    Moreno-Boza, Daniel; Iglesias, Immaculada; Sanchez, Antonio L.

    2016-11-01

    Frank-Kamenetskii's analysis of thermal explosions is applied, using also a single-reaction model with an Arrhenius rate having a large activation energy, to describe the evolution of an initially cold gaseous mixture flowing along a circular pipe with constant wall temperature for moderately large values of the relevant Reynolds number. The analysis shows two modes of combustion. There is a flameless slowly reacting mode for low wall temperatures or small pipe radii, when the temperature rise resulting from the heat released by the reaction is kept small by the heat-conduction losses to the wall, so as not to change significantly the order of magnitude of the reaction rate. In the other mode, the slow reaction rates occur only in an initial ignition stage, which ends abruptly when very large reaction rates cause a temperature runaway, or thermal explosion, at a well-defined ignition distance. The analysis determines the slow streamwise evolution for the flameless mode of combustion as well as the ignition distance for the explosive mode.

  11. Large-deflection statics analysis of active cardiac catheters through co-rotational modelling.

    PubMed

    Peng Qi; Chen Qiu; Mehndiratta, Aadarsh; I-Ming Chen; Haoyong Yu

    2016-08-01

    This paper presents a co-rotational concept for large-deflection formulation of cardiac catheters. Using this approach, the catheter is first discretized with a number of equal length beam elements and nodes, and the rigid body motions of an individual beam element are separated from its deformations. Therefore, it is adequate for modelling arbitrarily large deflections of a catheter with linear elastic analysis at the local element level. A novel design of active cardiac catheter of 9 Fr in diameter at the beginning of the paper is proposed, which is based on the contra-rotating double helix patterns and is improved from the previous prototypes. The modelling section is followed by MATLAB simulations of various deflections when the catheter is exerted different types of loads. This proves the feasibility of the presented modelling approach. To the best knowledge of the authors, it is the first to utilize this methodology for large-deflection static analysis of the catheter, which will enable more accurate control of robot-assisted cardiac catheterization procedures. Future work would include further experimental validations.

  12. Analysis of active surface reflector antenna for a large millimeter wave radio telescope

    NASA Astrophysics Data System (ADS)

    Cortes-Medellin, G.; Goldsmith, P. F.

    1994-02-01

    The authors analyze the effects of imperfect segment alignment on the aperture efficiency of a large millimeter telescope. A 50 meter diameter instrument of this type specified to operate to wavelengths as short as 1 mm is being designed with an actively controlled main surface. By simulating the performance of the control system, they generate samples of tilt and piston errors for the segments from which the antenna radiation patterns and aperture efficiencies are calculated. They make a comparison of these results with models of antenna tolerance theory developed by Ruze (1966), which relate the aperture efficiency to the RMS phase error. They find that Ruze's formulas have a different range of validity when the aperture RMS phase error, rather than the RMS surface error, is used as a parameter. When appreciable tilt errors are present in large segmented antennas, the aperture RMS phase error tends to a constant value, independent of the aperture illumination and of the shape of the segments. They conclude that the antenna RMS surface error is a better tracer of the aperture efficiency than is the aperture RMS phase error when Ruze's formula is used. They find that this well-known expression stands as a lower limit to the performance of large segmented reflector antennas.

  13. Active self-testing noise measurement sensors for large-scale environmental sensor networks.

    PubMed

    Domínguez, Federico; Cuong, Nguyen The; Reinoso, Felipe; Touhafi, Abdellah; Steenhaut, Kris

    2013-12-13

    Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10.

  14. Active Self-Testing Noise Measurement Sensors for Large-Scale Environmental Sensor Networks

    PubMed Central

    Domínguez, Federico; Cuong, Nguyen The; Reinoso, Felipe; Touhafi, Abdellah; Steenhaut, Kris

    2013-01-01

    Large-scale noise pollution sensor networks consist of hundreds of spatially distributed microphones that measure environmental noise. These networks provide historical and real-time environmental data to citizens and decision makers and are therefore a key technology to steer environmental policy. However, the high cost of certified environmental microphone sensors render large-scale environmental networks prohibitively expensive. Several environmental network projects have started using off-the-shelf low-cost microphone sensors to reduce their costs, but these sensors have higher failure rates and produce lower quality data. To offset this disadvantage, we developed a low-cost noise sensor that actively checks its condition and indirectly the integrity of the data it produces. The main design concept is to embed a 13 mm speaker in the noise sensor casing and, by regularly scheduling a frequency sweep, estimate the evolution of the microphone's frequency response over time. This paper presents our noise sensor's hardware and software design together with the results of a test deployment in a large-scale environmental network in Belgium. Our middle-range-value sensor (around €50) effectively detected all experienced malfunctions, in laboratory tests and outdoor deployments, with a few false positives. Future improvements could further lower the cost of our sensor below €10. PMID:24351634

  15. Stimulatory actions of a novel thiourea derivative on large-conductance, calcium-activated potassium channels.

    PubMed

    Wu, Sheng-Nan; Chern, Jyh-Haur; Shen, Santai; Chen, Hwei-Hisen; Hsu, Ying-Ting; Lee, Chih-Chin; Chan, Ming-Huan; Lai, Ming-Chi; Shie, Feng-Shiun

    2017-12-01

    In this study, we examine whether an anti-inflammatory thiourea derivative, compound #326, actions on ion channels. The effects of compound #326 on Ca(2+) -activated K(+) channels were evaluated by patch-clamp recordings obtained in cell-attached, inside-out or whole-cell configuration. In pituitary GH3 cells, compound #326 increased the amplitude of Ca(2+) -activated K(+) currents (IK(Ca) ) with an EC50 value of 11.6 μM, which was reversed by verruculogen, but not tolbutamide or TRAM-34. Under inside-out configuration, a bath application of compound #326 raised the probability of large-conductance Ca(2+) -activated K(+) (BKCa ) channels. The activation curve of BKCa channels was shifted to less depolarised potential with no modification of the gating charge of the curve; consequently, the difference of free energy was reduced in the presence of this compound. Compound #326-stimulated activity of BKCa channels is explained by a shortening of mean closed time, despite its inability to alter single-channel conductance. Neither delayed-rectifier nor erg-mediated K(+) currents was modified. Compound #326 decreased the peak amplitude of voltage-gated Na(+) current with no clear change in the overall current-voltage relationship of this current. In HEK293T cells expressing α-hSlo, compound #326 enhanced BKCa channels effectively. Intriguingly, the inhibitory actions of compound #326 on interleukin 1β in lipopolysaccharide-activated microglia were significantly reversed by verruculogen, whereas BKCa channel inhibitors suppressed the expressions of inducible nitric oxide synthase. The BKCa channels could be an important target for compound #326 if similar in vivo results occur, and the multi-functionality of BKCa channels in modulating microglial immunity merit further investigation. © 2017 Wiley Periodicals, Inc.

  16. Chronic active B-cell-receptor signalling in diffuse large B-cell lymphoma.

    PubMed

    Davis, R Eric; Ngo, Vu N; Lenz, Georg; Tolar, Pavel; Young, Ryan M; Romesser, Paul B; Kohlhammer, Holger; Lamy, Laurence; Zhao, Hong; Yang, Yandan; Xu, Weihong; Shaffer, Arthur L; Wright, George; Xiao, Wenming; Powell, John; Jiang, Jian-Kang; Thomas, Craig J; Rosenwald, Andreas; Ott, German; Muller-Hermelink, Hans Konrad; Gascoyne, Randy D; Connors, Joseph M; Johnson, Nathalie A; Rimsza, Lisa M; Campo, Elias; Jaffe, Elaine S; Wilson, Wyndham H; Delabie, Jan; Smeland, Erlend B; Fisher, Richard I; Braziel, Rita M; Tubbs, Raymond R; Cook, J R; Weisenburger, Dennis D; Chan, Wing C; Pierce, Susan K; Staudt, Louis M

    2010-01-07

    A role for B-cell-receptor (BCR) signalling in lymphomagenesis has been inferred by studying immunoglobulin genes in human lymphomas and by engineering mouse models, but genetic and functional evidence for its oncogenic role in human lymphomas is needed. Here we describe a form of 'chronic active' BCR signalling that is required for cell survival in the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). The signalling adaptor CARD11 is required for constitutive NF-kappaB pathway activity and survival in ABC DLBCL. Roughly 10% of ABC DLBCLs have mutant CARD11 isoforms that activate NF-kappaB, but the mechanism that engages wild-type CARD11 in other ABC DLBCLs was unknown. An RNA interference genetic screen revealed that a BCR signalling component, Bruton's tyrosine kinase, is essential for the survival of ABC DLBCLs with wild-type CARD11. In addition, knockdown of proximal BCR subunits (IgM, Ig-kappa, CD79A and CD79B) killed ABC DLBCLs with wild-type CARD11 but not other lymphomas. The BCRs in these ABC DLBCLs formed prominent clusters in the plasma membrane with low diffusion, similarly to BCRs in antigen-stimulated normal B cells. Somatic mutations affecting the immunoreceptor tyrosine-based activation motif (ITAM) signalling modules of CD79B and CD79A were detected frequently in ABC DLBCL biopsy samples but rarely in other DLBCLs and never in Burkitt's lymphoma or mucosa-associated lymphoid tissue lymphoma. In 18% of ABC DLBCLs, one functionally critical residue of CD79B, the first ITAM tyrosine, was mutated. These mutations increased surface BCR expression and attenuated Lyn kinase, a feedback inhibitor of BCR signalling. These findings establish chronic active BCR signalling as a new pathogenetic mechanism in ABC DLBCL, suggesting several therapeutic strategies.

  17. Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

    PubMed

    Copic, Davor; Hart, A John

    2015-04-22

    High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

  18. Synthesis of extremely large mesoporous activated carbon and its unique adsorption for giant molecules

    SciTech Connect

    Tamai, Hisashi; Kakii, Takuhiro; Hirota, Yoshifumi

    1996-02-01

    The steam invigoration of pitches (softening points 85 and 280{degrees}C) homogenized with 1-3 wt% of organo rare0earth metal complexes such as Ln(C{sub 5}H{sub 5}){sub 3} or Ln(acac) (Ln=Y, Yb) at 930{degrees}C provided activated carbons with an extremely high mesopore ration, >70%. The resulted activated carbon selectively adsorbs giant molecules such as Vitamin B{sub 12}, blue acid 90 dye, dextran, nystatin, and humic acid, reflecting their large mesopore volumes. To understand what kind of carbon skeleton in pitch is suited for generation of high mesopore ration, the steam invigoration of a series of condensed polynuclear aromatics (COPNA) resins prepared from naphthlene, anthracene, phenanthrene, pyrene, or perylene and p-xylene-{alpha},{alpha}{prime}-diol were conducted in the presence of rare-earth metal complexes. As a result, COPNA resins containing phenanthrene, perylene, and pyrene generated large mesopore volume. 35 refs., 16 figs., 11 tabs.

  19. Simultaneous Solar Maximum Mission (SMM) and Very Large Array (VLA) observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Willson, Robert F.

    1991-01-01

    Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

  20. Validation of the systemic lupus erythematosus activity questionnaire in a large observational cohort.

    PubMed

    Yazdany, Jinoos; Yelin, Edward H; Panopalis, Pantelis; Trupin, Laura; Julian, Laura; Katz, Patricia P

    2008-01-15

    To examine the reliability, construct validity, and responsiveness of the Systemic Lupus Erythematosus Activity Questionnaire (SLAQ) in a large observational cohort of persons with systemic lupus erythematosus (SLE). We evaluated the reliability of the SLAQ using Cronbach's alpha and principal factor analysis and ascertained construct validity by studying the association of the SLAQ with other clinically relevant, validated patient assessments of health. We estimated responsiveness by calculating standardized response means and analyzing the association of changes in SLAQ scores with changes in other patient assessments of health. The SLAQ had excellent reliability, as reflected by Cronbach's alpha (0.87) and principal factor analysis (one factor accounted for 92% of the variance). SLAQ scores were strongly correlated with other health indices, including the Short Form 12 Physical Component Summary and the Short Form 36 Physical Functioning subscale. Scores were significantly higher for respondents reporting a flare, more disease activity, hospitalization in the last year, concurrent use of immunosuppressive medication, and work disability. The SLAQ demonstrated a small to moderate degree of responsiveness; standardized response means were 0.66 and -0.37 for those reporting clinical worsening and improvement, respectively. Across a range of other patient assessments of disease status, the SLAQ had a response in the direction predicted by these other measures. The SLAQ demonstrates adequate reliability, construct validity, and responsiveness in our large, community-based cohort and appears to represent a promising tool for studies of SLE outside the clinical setting.

  1. Validation of the Systemic Lupus Erythematosus Activity Questionnaire in a Large Observational Cohort

    PubMed Central

    Yazdany, Jinoos; Yelin, Edward H.; Panopalis, Pantelis; Trupin, Laura; Julian, Laura; Katz, Patricia P.

    2013-01-01

    Objective To examine the reliability, construct validity, and responsiveness of the Systemic Lupus Erythematosus Activity Questionnaire (SLAQ) in a large observational cohort of persons with systemic lupus erythematosus (SLE). Methods We evaluated the reliability of the SLAQ using Cronbach's alpha and principal factor analysis and ascertained construct validity by studying the association of the SLAQ with other clinically relevant, validated patient assessments of health. We estimated responsiveness by calculating standardized response means and analyzing the association of changes in SLAQ scores with changes in other patient assessments of health. Results The SLAQ had excellent reliability, as reflected by Cronbach's alpha (0.87) and principal factor analysis (one factor accounted for 92% of the variance). SLAQ scores were strongly correlated with other health indices, including the Short Form 12 Physical Component Summary and the Short Form 36 Physical Functioning subscale. Scores were significantly higher for respondents reporting a flare, more disease activity, hospitalization in the last year, concurrent use of immunosuppressive medication, and work disability. The SLAQ demonstrated a small to moderate degree of responsiveness; standardized response means were 0.66 and −0.37 for those reporting clinical worsening and improvement, respectively. Across a range of other patient assessments of disease status, the SLAQ had a response in the direction predicted by these other measures. Conclusion The SLAQ demonstrates adequate reliability, construct validity, and responsiveness in our large, community-based cohort and appears to represent a promising tool for studies of SLE outside the clinical setting. PMID:18163398

  2. Active suspension design for a Large Space Structure ground test facility

    NASA Technical Reports Server (NTRS)

    Lange, Thomas J. H.; Schlegel, Clemens

    1993-01-01

    The expected future high performance requirements for Large Space Structures (LSS) enforce technology innovations such as active vibration damping techniques e.g., by means of structure sensors and actuators. The implementation of new technologies like that requires an interactive and integrated structural and control design with an increased effort in hardware validation by ground testing. During the technology development phase generic system tests will be most important covering verification and validation aspects up to the preparation and definition of relevant space experiments. For many applications using advanced designs it is deemed necessary to improve existing testing technology by further reducing disturbances and gravity coupling effects while maintaining high performance reliability. A key issue in this context is the improvement of suspension techniques. The ideal ground test facility satisfying these requirements completely will never be found. The highest degree of reliability will always be obtained by passive suspension methods taking into account severe performance limitations such as non-zero rigid body modes, restriction of degrees of freedom of motion and frequency response limitations. Passive compensation mechanisms, e.g., zero-spring-rate mechanisms, either require large moving masses or they are limited with respect to low-frequency performance by friction, stiction or other non-linear effects. With active suspensions these limitations can be removed to a large extent thereby increasing the range of applications. Despite an additional complexity which is associated with a potential risk in reliability their development is considered promising due to the amazing improvement of real-time control technology which is still continuing.

  3. Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish.

    PubMed

    Johansen, J L; Messmer, V; Coker, D J; Hoey, A S; Pratchett, M S

    2014-04-01

    Large-bodied fish are critical for sustaining coral reef fisheries, but little is known about the vulnerability of these fish to global warming. This study examined the effects of elevated temperatures on the movement and activity patterns of the common coral trout Plectropomus leopardus (Serranidae), which is an important fishery species in tropical Australia and throughout the Indo West-Pacific. Adult fish were collected from two locations on Australia's Great Barrier Reef (23°S and 14°S) and maintained at one of four temperatures (24, 27, 30, 33 °C). Following >4 weeks acclimation, the spontaneous swimming speeds and activity patterns of individuals were recorded over a period of 12 days. At 24-27 °C, spontaneous swimming speeds of common coral trout were 0.43-0.45 body lengths per second (bls(-1)), but dropped sharply to 0.29 bls(-1) at 30 °C and 0.25 bls(-1) at 33 °C. Concurrently, individuals spent 9.3-10.6% of their time resting motionless on the bottom at 24-27 °C, but this behaviour increased to 14.0% at 30 °C and 20.0% of the time at 33 °C (mean ± SE). The impact of temperature was greatest for smaller individuals (<45 cm TL), showing significant changes to swimming speeds across every temperature tested, while medium (45-55 cm TL) and large individuals (>55 cm TL) were first affected by 30 °C and 33 °C, respectively. Importantly, there was some indication that populations can adapt to elevated temperature if presented with adequate time, as the high-latitude population decreased significantly in swimming speeds at both 30 °C and 33 °C, while the low-latitude population only showed significant reductions at 33 °C. Given that movement and activity patterns of large mobile species are directly related to prey encounter rates, ability to capture prey and avoid predators, any reductions in activity patterns are likely to reduce overall foraging and energy intake, limit the energy available for growth and reproduction, and affect the fitness and

  4. Horizon: A Proposal for Large Aperture, Active Optics in Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Chesters, Dennis; Jenstrom, Del

    2000-01-01

    In 1999, NASA's New Millennium Program called for proposals to validate new technology in high-earth orbit for the Earth Observing-3 (NMP EO3) mission to fly in 2003. In response, we proposed to test a large aperture, active optics telescope in geosynchronous orbit. This would flight-qualify new technologies for both Earth and Space science: 1) a future instrument with LANDSAT image resolution and radiometric quality watching continuously from geosynchronous station, and 2) the Next Generation Space Telescope (NGST) for deep space imaging. Six enabling technologies were to be flight-qualified: 1) a 3-meter, lightweight segmented primary mirror, 2) mirror actuators and mechanisms, 3) a deformable mirror, 4) coarse phasing techniques, 5) phase retrieval for wavefront control during stellar viewing, and 6) phase diversity for wavefront control during Earth viewing. Three enhancing technologies were to be flight- validated: 1) mirror deployment and latching mechanisms, 2) an advanced microcontroller, and 3) GPS at GEO. In particular, two wavefront sensing algorithms, phase retrieval by JPL and phase diversity by ERIM International, were to sense optical system alignment and focus errors, and to correct them using high-precision mirror mechanisms. Active corrections based on Earth scenes are challenging because phase diversity images must be collected from extended, dynamically changing scenes. In addition, an Earth-facing telescope in GEO orbit is subject to a powerful diurnal thermal and radiometric cycle not experienced by deep-space astronomy. The Horizon proposal was a bare-bones design for a lightweight large-aperture, active optical system that is a practical blend of science requirements, emerging technologies, budget constraints, launch vehicle considerations, orbital mechanics, optical hardware, phase-determination algorithms, communication strategy, computational burdens, and first-rate cooperation among earth and space scientists, engineers and managers

  5. Targetable activating mutations are very frequent in GCB and ABC diffuse large B-cell lymphoma.

    PubMed

    Bohers, Elodie; Mareschal, Sylvain; Bouzelfen, Abdelilah; Marchand, Vinciane; Ruminy, Philippe; Maingonnat, Catherine; Ménard, Anne-Lise; Etancelin, Pascaline; Bertrand, Philippe; Dubois, Sydney; Alcantara, Marion; Bastard, Christian; Tilly, Hervé; Jardin, Fabrice

    2014-02-01

    Diffuse large B cell lymphoma (DLBCL) is an aggressive and heterogeneous malignancy that can be divided in two major subgroups, germinal center B-cell-like (GCB) and activated B-cell-like (ABC). Activating mutations of genes involved in the BCR and NF-κB pathways (CD79A, CD79B, MYD88, and CARD11) or in epigenetic regulation (EZH2) have been recently reported, preferentially in one of the two DLBCL subtypes. We analyzed the mutational status of these five recurrently mutated genes in a cohort of 161 untreated de novo DLBCL. Overall, 93 mutations were detected, in 61 (38%) of the patients. The L265P MYD88 mutation was the most frequent MYD88 variant (n = 18), observed exclusively in the ABC subtype. CD79A/CD79B ITAM domains were targeted in ABC DLBCL (12/77; 16%), whereas CARD11 mutations were equally distributed in the two subtypes. The EZH2 Y641 substitution was found almost exclusively in the GCB subgroup (15/62; 24%). Twenty cases (12%) displayed two activating mutations, including the most frequent CD79/MYD88 variants combination (n = 8) which is observed exclusively in the ABC subtype. When considering only ABC DLBCL patients treated by rituximab plus chemotherapy, the presence of an activating NF-κB mutation was associated with an unfavorable outcome (3-years OS 26% for mutated cases versus 67% for the cases without mutations, P = 0.0337). Our study demonstrates that activating and targetable mutations are observed at a very high frequency in DLBCL at the time of diagnosis, indicating that sequencing of a limited number of genes could help tailor an optimal treatment strategy in DLBCL. Copyright © 2013 Wiley Periodicals, Inc.

  6. Large-conductance calcium-activated potassium current modulates excitability in isolated canine intracardiac neurons

    PubMed Central

    Pérez, Guillermo J.; Desai, Mayurika; Anderson, Seth

    2013-01-01

    We studied principal neurons from canine intracardiac (IC) ganglia to determine whether large-conductance calcium-activated potassium (BK) channels play a role in their excitability. We performed whole cell recordings in voltage- and current-clamp modes to measure ion currents and changes in membrane potential from isolated canine IC neurons. Whole cell currents from these neurons showed fast- and slow-activated outward components. Both current components decreased in the absence of calcium and following 1–2 mM tetraethylammonium (TEA) or paxilline. These results suggest that BK channels underlie these current components. Single-channel analysis showed that BK channels from IC neurons do not inactivate in a time-dependent manner, suggesting that the dynamic of the decay of the fast current component is akin to that of intracellular calcium. Immunohistochemical studies showed that BK channels and type 2 ryanodine receptors are coexpressed in IC principal neurons. We tested whether BK current activation in these neurons occurred via a calcium-induced calcium release mechanism. We found that the outward currents of these neurons were not affected by the calcium depletion of intracellular stores with 10 mM caffeine and 10 μM cyclopiazonic acid. Thus, in canine intracardiac neurons, BK currents are directly activated by calcium influx. Membrane potential changes elicited by long (400 ms) current injections showed a tonic firing response that was decreased by TEA or paxilline. These data strongly suggest that the BK current present in canine intracardiac neurons regulates action potential activity and could increase these neurons excitability. PMID:23195072

  7. Up-Regulatory Effects of Curcumin on Large Conductance Ca2+-Activated K+ Channels

    PubMed Central

    Hei, Hongya; Li, Fangping; Wang, Yunman; Peng, Wen; Zhang, Xuemei

    2015-01-01

    Large conductance Ca2+-activated potassium channels (BK) are targets for research that explores therapeutic means to various diseases, owing to the roles of the channels in mediating multiple physiological processes in various cells and tissues. We investigated the pharmacological effects of curcumin, a compound isolated from the herb Curcuma longa, on BK channels. As recorded by whole-cell patch-clamp, curcumin increased BK (α) and BK (α+β1) currents in transfected HEK293 cells as well as the current density of BK in A7r5 smooth muscle cells in a dose-dependent manner. By incubating with curcumin for 24 hours, the current density of exogenous BK (α) in HEK293 cells and the endogenous BK in A7r5 cells were both enhanced notably, though the steady-state activation of the channels did not shift significantly, except for BK (α+β1). Curcumin up-regulated the BK protein expression without changing its mRNA level in A7r5 cells. The surface expression and the half-life of BK channels were also increased by curcumin in HEK293 cells. These effects of curcumin were abolished by MG-132, a proteasome inhibitor. Curcumin also increased ERK 1/2 phosphorylation, while inhibiting ERK by U0126 attenuated the curcumin-induced up-regulation of BK protein expression. We also observed that the curcumin-induced relaxation in the isolated rat aortic rings was significantly attenuated by paxilline, a BK channel specific blocker. These results show that curcumin enhances the activity of the BK channels by interacting with BK directly as well as enhancing BK protein expression through inhibiting proteasomal degradation and activating ERK signaling pathway. The findings suggest that curcumin is a potential BK channel activator and provide novel insight into its complicated pharmacological effects and the underlying mechanisms. PMID:26672753

  8. Large-conductance Ca2+-activated potassium channels in secretory neurons.

    PubMed

    Lara, J; Acevedo, J J; Onetti, C G

    1999-09-01

    Large-conductance Ca2+-activated K+ channels (BK) are believed to underlie interburst intervals and contribute to the control of hormone release in several secretory cells. In crustacean neurosecretory cells, Ca2+ entry associated with electrical activity could act as a modulator of membrane K+ conductance. Therefore we studied the contribution of BK channels to the macroscopic outward current in the X-organ of crayfish, and their participation in electrophysiological activity, as well as their sensitivity toward intracellular Ca2+, ATP, and voltage, by using the patch-clamp technique. The BK channels had a conductance of 223 pS and rectified inwardly in symmetrical K+. These channels were highly selective to K+ ions; potassium permeability (PK) value was 2.3 x 10(-13) cm(3) s(-1). The BK channels were sensitive to internal Ca2+ concentration, voltage dependent, and activated by intracellular MgATP. Voltage sensitivity (k) was approximately 13 mV, and the half-activation membrane potentials depended on the internal Ca2+ concentration. Calcium ions (0.3-3 microM) applied to the internal membrane surface caused an enhancement of the channel activity. This activation of BK channels by internal calcium had a KD(0) of 0.22 microM and was probably due to the binding of only one or two Ca2+ ions to the channel. Addition of MgATP (0.01-3 mM) to the internal solution increased steady state-open probability. The dissociation constant for MgATP (KD) was 119 microM, and the Hill coefficient (h) was 0.6, according to the Hill analysis. Ca2+-activated K+ currents recorded from whole cells were suppressed by either adding Cd2+ (0.4 mM) or removing Ca2+ ions from the external solution. TEA (1 mM) or charybdotoxin (100 nM) blocked these currents. Our results showed that both BK and K(ATP) channels are present in the same cell. Even when BK and K(ATP) channels were voltage dependent and modulated by internal Ca2+ and ATP, the profile of sensitivity was quite different for each kind

  9. Nitric oxide deficit in chronic intermittent hypoxia impairs large conductance calcium-activated potassium channel activity in rat hippocampal neurons.

    PubMed

    Tjong, Yung-Wui; Li, Meifang; Hung, Ming-Wai; Wang, Kun; Fung, Man-Lung

    2008-02-15

    Sleep apnea associated with chronic intermittent hypoxia (IH) impairs hippocampal functions but the pathogenic mechanisms involving dysfunction of nitric oxide (NO) and ionic channels remain unclear. We examined the hypothesis that hippocampal NO deficit impairs the activity of large conductance calcium-activated potassium (BK) channels in rats with chronic IH, mimicking conditions in patients with sleep apnea. A patch-clamp study was performed on hippocampal CA1 neurons acutely dissociated from IH and control rats. The levels of endogenous NO and intracellular calcium in the CA1 region of the hippocampal slices were measured respectively by electrochemical microsensors and spectrofluorometry. We found that the open probability of BK channels remarkably decreased in the CA1 pyramidal neurons in a time-dependent manner with the IH treatment, without changes in the unitary conductance and reversal potential. NO donors, SNP or DETA/NO, significantly restored the activity of BK channels in the IH neurons, which was prevented by blockade of S-nitrosylation with NEM or MTSES but not by inhibition of the cGMP pathway with ODQ or 8-bromo-cGMP. Endogenous NO levels were substantially lowered in the IH hippocampus during resting and hypoxia. Also, the level of protein expression of neuronal NO synthase was markedly lessened in the IH neurons with decreased intracellular calcium response to hypoxia. Collectively, the results suggest that the IH-induced NO deficit mediated by a down-regulation of the expression of neuronal NO synthase plays a causative role in the impaired activity of BK channels, which could account for the hippocampal injury in patients with sleep apnea.

  10. WNK1 Activates Large-Conductance Ca2+-Activated K+ Channels through Modulation of ERK1/2 Signaling

    PubMed Central

    Liu, Yingli; Song, Xiang; Shi, Yanling; Shi, Zhen; Niu, Weihui; Feng, Xiuyan; Gu, Dingying; Bao, Hui-Fang; Ma, He-Ping; Eaton, Douglas C.

    2015-01-01

    With no lysine (WNK) kinases are members of the serine/threonine kinase family. We previously showed that WNK4 inhibits renal large-conductance Ca2+-activated K+ (BK) channel activity by enhancing its degradation through a lysosomal pathway. In this study, we investigated the effect of WNK1 on BK channel activity. In HEK293 cells stably expressing the α subunit of BK (HEK-BKα cells), siRNA-mediated knockdown of WNK1 expression significantly inhibited both BKα channel activity and open probability. Knockdown of WNK1 expression also significantly inhibited BKα protein expression and increased ERK1/2 phosphorylation, whereas overexpression of WNK1 significantly enhanced BKα expression and decreased ERK1/2 phosphorylation in a dose-dependent manner in HEK293 cells. Knockdown of ERK1/2 prevented WNK1 siRNA-mediated inhibition of BKα expression. Similarly, pretreatment of HEK-BKα cells with the lysosomal inhibitor bafilomycin A1 reversed the inhibitory effects of WNK1 siRNA on BKα expression in a dose-dependent manner. Knockdown of WNK1 expression also increased the ubiquitination of BKα channels. Notably, mice fed a high-K+ diet for 10 days had significantly higher renal protein expression levels of BKα and WNK1 and lower levels of ERK1/2 phosphorylation compared with mice fed a normal-K+ diet. These data suggest that WNK1 enhances BK channel function by reducing ERK1/2 signaling-mediated lysosomal degradation of the channel. PMID:25145935

  11. Nature and timing of large landslides within an active orogen, eastern Pamir, China

    NASA Astrophysics Data System (ADS)

    Yuan, Zhaode; Chen, Jie; Owen, Lewis A.; Hedrick, Kathryn A.; Caffee, Marc W.; Li, Wenqiao; Schoenbohm, Lindsay M.; Robinson, Alexander C.

    2013-01-01

    Large-scale landsliding (involving ≫ 106 m3 in volume) is important in landscape development in high mountains. To assess the importance of large landslides in high mountains, four large landslides (Bulunkou, Muztagh, Taheman, and Yimake) were mapped in the NE Chinese Pamir at the westernmost end of the Himalayan-Tibetan orogen and dated using 10Be terrestrial cosmogenic nuclides. The Bulunkou landslide at the southernmost end of Muji Valley is composed of ~ 1.7 × 107 m3 of landslide debris and has an age of 2.0 ± 0.1 ka. The Muztagh landslide, located on the SW side of the massif Muztagh Ata, is composed of ~ 4.7 × 108 m3 of debris, and has an age of 14.3 ± 0.8 ka. The Taheman landslide, located south of Muztagh Ata, is composed of ~ 2.6 × 108 m3 of landslide debris and has an age of 6.8 ± 0.2 ka. The Yimake landslide, on the northern frontal range of the Pamir at the southwestern end of the Tarim basin, is composed of ~ 1.4 × 109 m3 of landslide debris and has an age of 7.1 ± 0.6 ka. Two other large landslides are present in the region, the Aerpa Aigezi (on a tributary of the Gez River) and the Bile Jiyi (on the Yarkand River) landslides, and are composed of ~ 1.6 × 107 m3 and ~ 5.2 × 106 m3 of landslide debris, respectively. However, the Aerpa Aigezi and Bile Jiyi landslides were not studied in as much detail or dated because of their inaccessibility. Given the tectonically active nature of this region, with numerous active faults, and the morphology of the landslides, these landslides were likely triggered by earthquakes. However, other causes — including long-term increased precipitation and geologic bedrock structure — could be important contributing factors in their formation.

  12. Laboratory demonstration of a primary active mirror for space with the LATT: large aperture telescope technology

    NASA Astrophysics Data System (ADS)

    Briguglio, Runa; Biasi, Roberto; Gallieni, Daniele; Vettore, Christian; d'Amato, Francesco; Xompero, Marco; Arcidiacono, Carmelo; Lisi, Franco; Riccardi, Armando; Patauner, Christian; Lazzarini, Paolo; Tintori, Matteo; Duò, Fabrizio; Pucci, Mauro; Zuccaro Marchi, Alessandro; Maresi, Luca

    2016-07-01

    The LATT project is an ESA contract under TRP programme to demonstrate the scalability of the technology from ground-based adaptive mirrors to space active primary mirrors. A prototype spherical mirror based on a 40 cm diameter 1 mm thin glass shell with 19 contactless, voice-coil actuators and co-located position sensors have been manufactured and integrated into a final unit with an areal density lower than 20 kg/m2. Laboratory tests demonstrated the controllability with very low power budget and the survival of the fragile glass shell exposed to launch accelerations, thanks to an electrostatic locking mechanism; such achievements pushes the technology readiness level toward 5. With this prototype, the LATT project explored the feasibility of using an active and lightweight primary for space telescopes. The concept is attractive for large segmented telescopes, with surface active control to shape and co-phase them once in flight. In this paper we will describe the findings of the technological advances and the results of the environmental and optical tests.

  13. Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse.

    PubMed

    Vincent, Jean-Baptiste; Bodewits, Dennis; Besse, Sébastien; Sierks, Holger; Barbieri, Cesare; Lamy, Philippe; Rodrigo, Rafael; Koschny, Detlef; Rickman, Hans; Keller, Horst Uwe; Agarwal, Jessica; A'Hearn, Michael F; Auger, Anne-Thérèse; Barucci, M Antonella; Bertaux, Jean-Loup; Bertini, Ivano; Capanna, Claire; Cremonese, Gabriele; Da Deppo, Vania; Davidsson, Björn; Debei, Stefano; De Cecco, Mariolino; El-Maarry, Mohamed Ramy; Ferri, Francesca; Fornasier, Sonia; Fulle, Marco; Gaskell, Robert; Giacomini, Lorenza; Groussin, Olivier; Guilbert-Lepoutre, Aurélie; Gutierrez-Marques, P; Gutiérrez, Pedro J; Güttler, Carsten; Hoekzema, Nick; Höfner, Sebastian; Hviid, Stubbe F; Ip, Wing-Huen; Jorda, Laurent; Knollenberg, Jörg; Kovacs, Gabor; Kramm, Rainer; Kührt, Ekkehard; Küppers, Michael; La Forgia, Fiorangela; Lara, Luisa M; Lazzarin, Monica; Lee, Vicky; Leyrat, Cédric; Lin, Zhong-Yi; Lopez Moreno, Josè J; Lowry, Stephen; Magrin, Sara; Maquet, Lucie; Marchi, Simone; Marzari, Francesco; Massironi, Matteo; Michalik, Harald; Moissl, Richard; Mottola, Stefano; Naletto, Giampiero; Oklay, Nilda; Pajola, Maurizio; Preusker, Frank; Scholten, Frank; Thomas, Nicolas; Toth, Imre; Tubiana, Cecilia

    2015-07-02

    Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.

  14. A general second order complete active space self-consistent-field solver for large-scale systems

    NASA Astrophysics Data System (ADS)

    Sun, Qiming; Yang, Jun; Chan, Garnet Kin-Lic

    2017-09-01

    We present a new second order complete active space self-consistent field implementation to converge wavefunctions for both large active spaces and large atomic orbital (AO) bases. Our algorithm decouples the active space wavefunction solver from the orbital optimization in the microiterations, and thus may be easily combined with various modern active space solvers. We also introduce efficient approximate orbital gradient and Hessian updates, and step size determination. We demonstrate its capabilities by calculating the low-lying states of the Fe(II)-porphine complex with modest resources using a density matrix renormalization group solver in a CAS(22, 27) active space and a 3000 AO basis.

  15. Mapping the Daily Progression of Large Wildland Fires Using MODIS Active Fire Data

    NASA Technical Reports Server (NTRS)

    Veraverbeke, Sander; Sedano, Fernando; Hook, Simon J.; Randerson, James T.; Jin, Yufang; Rogers, Brendan

    2013-01-01

    High temporal resolution information on burned area is a prerequisite for incorporating bottom-up estimates of wildland fire emissions in regional air transport models and for improving models of fire behavior. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire product (MO(Y)D14) as input to a kriging interpolation to derive continuous maps of the evolution of nine large wildland fires. For each fire, local input parameters for the kriging model were defined using variogram analysis. The accuracy of the kriging model was assessed using high resolution daily fire perimeter data available from the U.S. Forest Service. We also assessed the temporal reporting accuracy of the MODIS burned area products (MCD45A1 and MCD64A1). Averaged over the nine fires, the kriging method correctly mapped 73% of the pixels within the accuracy of a single day, compared to 33% for MCD45A1 and 53% for MCD64A1.

  16. On the accuracy of protein determination in large biological samples by prompt gamma neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Kasviki, K.; Stamatelatos, I. E.; Yannakopoulou, E.; Papadopoulou, P.; Kalef-Ezra, J.

    2007-10-01

    A prompt gamma neutron activation analysis (PGNAA) facility has been developed for the determination of nitrogen and thus total protein in large volume biological samples or the whole body of small animals. In the present work, the accuracy of nitrogen determination by PGNAA in phantoms of known composition as well as in four raw ground meat samples of about 1 kg mass was examined. Dumas combustion and Kjeldahl techniques were also used for the assessment of nitrogen concentration in the meat samples. No statistically significant differences were found between the concentrations assessed by the three techniques. The results of this work demonstrate the applicability of PGNAA for the assessment of total protein in biological samples of 0.25-1.5 kg mass, such as a meat sample or the body of small animal even in vivo with an equivalent radiation dose of about 40 mSv.

  17. Stress-related noradrenergic activity prompts large-scale neural network reconfiguration.

    PubMed

    Hermans, Erno J; van Marle, Hein J F; Ossewaarde, Lindsey; Henckens, Marloes J A G; Qin, Shaozheng; van Kesteren, Marlieke T R; Schoots, Vincent C; Cousijn, Helena; Rijpkema, Mark; Oostenveld, Robert; Fernández, Guillén

    2011-11-25

    Acute stress shifts the brain into a state that fosters rapid defense mechanisms. Stress-related neuromodulators are thought to trigger this change by altering properties of large-scale neural populations throughout the brain. We investigated this brain-state shift in humans. During exposure to a fear-related acute stressor, responsiveness and interconnectivity within a network including cortical (frontoinsular, dorsal anterior cingulate, inferotemporal, and temporoparietal) and subcortical (amygdala, thalamus, hypothalamus, and midbrain) regions increased as a function of stress response magnitudes. β-adrenergic receptor blockade, but not cortisol synthesis inhibition, diminished this increase. Thus, our findings reveal that noradrenergic activation during acute stress results in prolonged coupling within a distributed network that integrates information exchange between regions involved in autonomic-neuroendocrine control and vigilant attentional reorienting.

  18. Directed Evolution of RebH for Site Selective Halogenation of Large, Biologically Active Molecules**

    PubMed Central

    Payne, James T.; Poor, Catherine B.

    2015-01-01

    We recently characterized the substrate scope of wild-type RebH and evolved variants of this enzyme with improved stability for biocatalysis. The substrate scopes of both RebH and the stabilized variants, however, are limited primarily to compounds similar in size to tryptophan. We have now used a substrate walking approach to further evolve RebH variants with expanded substrate scope. Two particularly notable variants were identified: 3-SS, which provides high conversion of tricyclic tryptoline derivatives; and 4-V, which accepts a broad range of large indoles and carbazoles. This constitutes the first reported use of directed evolution to enable functionalization of substrates not accepted by wild-type RebH and demonstrates the utility of RebH variants for site-selective halogenation of biologically active compounds. PMID:25678465

  19. Response of extratropical cyclone activity to the Kuroshio large meander in northern winter

    NASA Astrophysics Data System (ADS)

    Hayasaki, Masamitsu; Kawamura, Ryuichi; Mori, Masato; Watanabe, Masahiro

    2013-06-01

    We examined possible responses of cyclone activities to the bimodal path states of the Kuroshio Current [i.e., large meander (LM) and non-LM (NLM)] by using the long-term reanalysis data and the 20th century hindcast experiment of a high-resolution atmosphere-ocean coupled model. Compared with a seasonal mean cyclone track frequency for the LM and NLM periods, a primary cyclone track shifts southward in association with the meander of Kuroshio Current. Composite analyses of the hindcast experiment showed remarkable atmospheric responses accompanying the Kuroshio LM. The Kuroshio LM causes a decrease in latent heat flux in the south of Japan and a southward shift of the near-surface baroclinic zone. Distinctive decreases in thermodynamic fluxes inhibit the rapid development of cyclones in the meander region, eventually inducing positive sea level pressure anomalies downstream from that region.

  20. Correlation Analysis of Optical and Radio Light Curves for a Large Sample of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Clements, S. D.; Smith, A. G.; Aller, H. D.; Aller, M. F.

    1995-08-01

    The Rosemary Hill Observatory has accumulated internally consistent light curves extending over as much as 26 years for a large sample of active galactic nuclei. Forty-six of these optical records have been compared with similar radio records from the University of Michigan Radio Astronomy Observatory and the Algonquin Radio Observatory. For 18 objects, pairs of records were sufficiently long and unconfused to allow reliable application of the Discrete Correlation Function analysis; this group included 8 BL Lacertids, 8 quasars, and 2 Seyfert galaxies. Nine of the 18 sources showed positive radio-optical correlations, with the radio events lagging the optical by intervals ranging from 0 to 14 months. Consistent with the relativistic beaming model of the BL Lacertids, the group displaying correlations was dominated by this type of object.

  1. Consistent estimation of complete neuronal connectivity in large neuronal populations using sparse "shotgun" neuronal activity sampling.

    PubMed

    Mishchenko, Yuriy

    2016-10-01

    We investigate the properties of recently proposed "shotgun" sampling approach for the common inputs problem in the functional estimation of neuronal connectivity. We study the asymptotic correctness, the speed of convergence, and the data size requirements of such an approach. We show that the shotgun approach can be expected to allow the inference of complete connectivity matrix in large neuronal populations under some rather general conditions. However, we find that the posterior error of the shotgun connectivity estimator grows quickly with the size of unobserved neuronal populations, the square of average connectivity strength, and the square of observation sparseness. This implies that the shotgun connectivity estimation will require significantly larger amounts of neuronal activity data whenever the number of neurons in observed neuronal populations remains small. We present a numerical approach for solving the shotgun estimation problem in general settings and use it to demonstrate the shotgun connectivity inference in the examples of simulated synfire and weakly coupled cortical neuronal networks.

  2. Mapping the Daily Progression of Large Wildland Fires Using MODIS Active Fire Data

    NASA Technical Reports Server (NTRS)

    Veraverbeke, Sander; Sedano, Fernando; Hook, Simon J.; Randerson, James T.; Jin, Yufang; Rogers, Brendan

    2013-01-01

    High temporal resolution information on burned area is a prerequisite for incorporating bottom-up estimates of wildland fire emissions in regional air transport models and for improving models of fire behavior. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire product (MO(Y)D14) as input to a kriging interpolation to derive continuous maps of the evolution of nine large wildland fires. For each fire, local input parameters for the kriging model were defined using variogram analysis. The accuracy of the kriging model was assessed using high resolution daily fire perimeter data available from the U.S. Forest Service. We also assessed the temporal reporting accuracy of the MODIS burned area products (MCD45A1 and MCD64A1). Averaged over the nine fires, the kriging method correctly mapped 73% of the pixels within the accuracy of a single day, compared to 33% for MCD45A1 and 53% for MCD64A1.

  3. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  4. From baseline to epileptiform activity: A path to synchronized rhythmicity in large-scale neural networks

    NASA Astrophysics Data System (ADS)

    Shusterman, Vladimir; Troy, William C.

    2008-06-01

    In large-scale neural networks in the brain the emergence of global behavioral patterns, manifested by electroencephalographic activity, is driven by the self-organization of local neuronal groups into synchronously functioning ensembles. However, the laws governing such macrobehavior and its disturbances, in particular epileptic seizures, are poorly understood. Here we use a mean-field population network model to describe a state of baseline physiological activity and the transition from the baseline state to rhythmic epileptiform activity. We describe principles which explain how this rhythmic activity arises in the form of spatially uniform self-sustained synchronous oscillations. In addition, we show how the rate of migration of the leading edge of the synchronous oscillations can be theoretically predicted, and compare the accuracy of this prediction with that measured experimentally using multichannel electrocorticographic recordings obtained from a human subject experiencing epileptic seizures. The comparison shows that the experimentally measured rate of migration of the leading edge of synchronous oscillations is within the theoretically predicted range of values. Computer simulations have been performed to investigate the interactions between different regions of the brain and to show how organization in one spatial region can promote or inhibit organization in another. Our theoretical predictions are also consistent with the results of functional magnetic resonance imaging (fMRI), in particular with observations that lower-frequency electroencephalographic (EEG) rhythms entrain larger areas of the brain than higher-frequency rhythms. These findings advance the understanding of functional behavior of interconnected populations and might have implications for the analysis of diverse classes of networks.

  5. Erectile dysfunction in mice lacking the large-conductance calcium-activated potassium (BK) channel

    PubMed Central

    Werner, Matthias E; Zvara, Peter; Meredith, Andrea L; Aldrich, Richard W; Nelson, Mark T

    2005-01-01

    Penile erection is dependent on the nitric oxide (NO)/cGMP-dependent protein kinase I (PKGI) pathway. One important target of PKGI in smooth muscle is the large-conductance, calcium-activated potassium (BK) channel, which upon activation hyperpolarizes the smooth muscle cell membrane, causing relaxation. Relaxation of arterial and corpus cavernosum smooth muscle (CCSM) is necessary to increase blood flow into the corpora cavernosa that leads to penile tumescence. We investigated the functional role of BK channels in the corpus cavernosum utilizing a knock-out mouse lacking the Slo gene (Slo−/−) responsible for the pore-forming subunit of the BK channel. Whole-cell currents were recorded from isolated CCSM cells of Slo+/+ and Slo−/− mice. Iberiotoxin-sensitive voltage- and [Ca2+]-activated K+ currents, the latter activated by local transient calcium releases (calcium sparks), were present in Slo+/+ CCSM cells, but absent in Slo−/− cells. CCSM strips from Slo−/− mice demonstrated a four-fold increase in phasic contractions, in the presence of phenylephrine. Nerve-evoked relaxations of precontracted strips were reduced by 50%, both in strips from Slo−/− mice and by blocking BK channels with iberiotoxin in the Slo+/+ strips. Consistent with the in vitro results, in vivo intracavernous pressure exhibited pronounced oscillations in Slo−/− mice, but not in Slo+/+ mice. Furthermore, intracavernous pressure increases to nerve stimulation, in vivo, were reduced by 22% in Slo−/−mice. These results indicate that the BK channel has an important role in erectile function, and loss of the BK channel leads to erectile dysfunction. PMID:16020453

  6. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  7. Raman Optical Activity Spectra for Large Molecules through Molecules-in-Molecules Fragment-Based Approach.

    PubMed

    Jovan Jose, K V; Raghavachari, Krishnan

    2016-02-09

    We present an efficient method for the calculation of the Raman optical activity (ROA) spectra for large molecules through the molecules-in-molecules (MIM) fragment-based method. The relevant higher energy derivatives from smaller fragments are used to build the property tensors of the parent molecule to enable the extension of the MIM method for evaluating ROA spectra (MIM-ROA). Two factors were found to be particularly important in yielding accurate results. First, the link-atom tensor components are projected back onto the corresponding host and supporting atoms through the Jacobian projection method, yielding a mathematically rigorous method. Second, the long-range interactions between fragments are taken into account by using a less computationally expensive lower level of theory. The performance of the MIM-ROA model is calibrated on the enantiomeric pairs of 10 carbohydrate benchmark molecules, with strong intramolecular interactions. The vibrational frequencies and ROA intensities are accurately reproduced relative to the full, unfragmented, results for these systems. In addition, the MIM-ROA method is employed to predict the ROA spectra of d-maltose, α-D-cyclodextrin, and cryptophane-A, yielding spectra in excellent agreement with experiment. The accuracy and performance of the benchmark systems validate the MIM-ROA model for exploring ROA spectra of large molecules.

  8. Heterogeneity-induced large deviations in activity and (in some cases) entropy production

    NASA Astrophysics Data System (ADS)

    Gingrich, Todd R.; Vaikuntanathan, Suriyanarayanan; Geissler, Phillip L.

    2014-10-01

    We solve a simple model that supports a dynamic phase transition and show conditions for the existence of the transition. Using methods of large deviation theory we analytically compute the probability distribution for activity and entropy production rates of the trajectories on a large ring with a single heterogeneous link. The corresponding joint rate function demonstrates two dynamical phases—one localized and the other delocalized, but the marginal rate functions do not always exhibit the underlying transition. Symmetries in dynamic order parameters influence the observation of a transition, such that distributions for certain dynamic order parameters need not reveal an underlying dynamical bistability. Solution of our model system furthermore yields the form of the effective Markov transition matrices that generate dynamics in which the two dynamical phases are at coexistence. We discuss the implications of the transition for the response of bacterial cells to antibiotic treatment, arguing that even simple models of a cell cycle lacking an explicit bistability in configuration space will exhibit a bistability of dynamical phases.

  9. Techniques for extracting single-trial activity patterns from large-scale neural recordings

    PubMed Central

    Churchland, Mark M; Yu, Byron M; Sahani, Maneesh; Shenoy, Krishna V

    2008-01-01

    Summary Large, chronically-implanted arrays of microelectrodes are an increasingly common tool for recording from primate cortex, and can provide extracellular recordings from many (order of 100) neurons. While the desire for cortically-based motor prostheses has helped drive their development, such arrays also offer great potential to advance basic neuroscience research. Here we discuss the utility of array recording for the study of neural dynamics. Neural activity often has dynamics beyond that driven directly by the stimulus. While governed by those dynamics, neural responses may nevertheless unfold differently for nominally identical trials, rendering many traditional analysis methods ineffective. We review recent studies – some employing simultaneous recording, some not – indicating that such variability is indeed present both during movement generation, and during the preceding premotor computations. In such cases, large-scale simultaneous recordings have the potential to provide an unprecedented view of neural dynamics at the level of single trials. However, this enterprise will depend not only on techniques for simultaneous recording, but also on the use and further development of analysis techniques that can appropriately reduce the dimensionality of the data, and allow visualization of single-trial neural behavior. PMID:18093826

  10. Active fault slip and potential large magnitude earthquakes within the stable Kazakh Platform (Central Kazakhstan)

    NASA Astrophysics Data System (ADS)

    Hollingsworth, J.; Walker, R. T.; Abdrakhmatov, K.; Campbell, G.; Mukambayev, A.; Rhodes, E.; Rood, D. H.

    2016-12-01

    sampling of earthquakes preserved in the young geomorphology. Nevertheless, our results indicate the DNF is an active structure, accommodating a small fraction of the ongoing India-Eurasia collision, and is capable of producing large earthquakes. The DNF provides an important example of a slow-moving active fault in a relatively stable continental interior.

  11. Large-Scale Activity in the Bastille Day 2000 Solar Event

    NASA Astrophysics Data System (ADS)

    Chertok, I. M.; Grechnev, V. V.

    2005-06-01

    We have analyzed dimmings, i.e., regions of temporarily reduced brightness, and manifestations of a coronal wave in the famous event of 14 July 2000 using images produced with the EUV telescope SOHO/EIT. Our analysis was inspired by a paper by Andrews (2001, Solar Phys. 204, 181 (Paper I)), in which this event was studied using running-difference EIT images at 195 Å formed by subtraction of a previous image from each current one. Such images emphasize changes of the brightness, location, and configuration of observed structures occurring during the 12-min interval between two subsequent heliograms. However, they distort the picture of large-scale disturbances caused by a CME, particularly, dimmings. A real picture of dimmings can be obtained from fixed-base difference ‘de-rotated’ images. The latter are formed in two stages: first, the solar rotation is compensated using three-dimensional rotation of all images (‘de-rotation’) to the time of a pre-event heliogram, here 10:00 UT, and then the base heliogram is subtracted from all others. We show real dimmings to be essentially different from those described by Andrews (Paper I). The restructuring of large-scale magnetic fields in the corona in connection with the CME was accompanied by the appearance and growth of two large dimmings. One of them was located along the central meridian, southward of the eruption center, at the place of the pre-eruption arcade. Another dimming occupied the space between the flare region and a remote western active region. Several smaller dimmings were observed virtually over the whole solar disk, especially, within the northwest quadrant. We have also revealed a propagating disturbance with properties of a coronal wave in the northern polar sector, where no dimmings were observed. This fact is discussed in the context of probable association between dimmings and coronal waves. Having suppressed the ‘snowstorm’ produced in the EIT images by energetic particles, we have

  12. GMP Cryopreservation of Large Volumes of Cells for Regenerative Medicine: Active Control of the Freezing Process

    PubMed Central

    Massie, Isobel; Selden, Clare; Hodgson, Humphrey; Gibbons, Stephanie; Morris, G. John

    2014-01-01

    Cryopreservation protocols are increasingly required in regenerative medicine applications but must deliver functional products at clinical scale and comply with Good Manufacturing Process (GMP). While GMP cryopreservation is achievable on a small scale using a Stirling cryocooler-based controlled rate freezer (CRF) (EF600), successful large-scale GMP cryopreservation is more challenging due to heat transfer issues and control of ice nucleation, both complex events that impact success. We have developed a large-scale cryocooler-based CRF (VIA Freeze) that can process larger volumes and have evaluated it using alginate-encapsulated liver cell (HepG2) spheroids (ELS). It is anticipated that ELS will comprise the cellular component of a bioartificial liver and will be required in volumes of ∼2 L for clinical use. Sample temperatures and Stirling cryocooler power consumption was recorded throughout cooling runs for both small (500 μL) and large (200 mL) volume samples. ELS recoveries were assessed using viability (FDA/PI staining with image analysis), cell number (nuclei count), and function (protein secretion), along with cryoscanning electron microscopy and freeze substitution techniques to identify possible injury mechanisms. Slow cooling profiles were successfully applied to samples in both the EF600 and the VIA Freeze, and a number of cooling and warming profiles were evaluated. An optimized cooling protocol with a nonlinear cooling profile from ice nucleation to −60°C was implemented in both the EF600 and VIA Freeze. In the VIA Freeze the nucleation of ice is detected by the control software, allowing both noninvasive detection of the nucleation event for quality control purposes and the potential to modify the cooling profile following ice nucleation in an active manner. When processing 200 mL of ELS in the VIA Freeze—viabilities at 93.4%±7.4%, viable cell numbers at 14.3±1.7 million nuclei/mL alginate, and protein secretion at 10.5±1.7

  13. GMP cryopreservation of large volumes of cells for regenerative medicine: active control of the freezing process.

    PubMed

    Massie, Isobel; Selden, Clare; Hodgson, Humphrey; Fuller, Barry; Gibbons, Stephanie; Morris, G John

    2014-09-01

    Cryopreservation protocols are increasingly required in regenerative medicine applications but must deliver functional products at clinical scale and comply with Good Manufacturing Process (GMP). While GMP cryopreservation is achievable on a small scale using a Stirling cryocooler-based controlled rate freezer (CRF) (EF600), successful large-scale GMP cryopreservation is more challenging due to heat transfer issues and control of ice nucleation, both complex events that impact success. We have developed a large-scale cryocooler-based CRF (VIA Freeze) that can process larger volumes and have evaluated it using alginate-encapsulated liver cell (HepG2) spheroids (ELS). It is anticipated that ELS will comprise the cellular component of a bioartificial liver and will be required in volumes of ∼2 L for clinical use. Sample temperatures and Stirling cryocooler power consumption was recorded throughout cooling runs for both small (500 μL) and large (200 mL) volume samples. ELS recoveries were assessed using viability (FDA/PI staining with image analysis), cell number (nuclei count), and function (protein secretion), along with cryoscanning electron microscopy and freeze substitution techniques to identify possible injury mechanisms. Slow cooling profiles were successfully applied to samples in both the EF600 and the VIA Freeze, and a number of cooling and warming profiles were evaluated. An optimized cooling protocol with a nonlinear cooling profile from ice nucleation to -60°C was implemented in both the EF600 and VIA Freeze. In the VIA Freeze the nucleation of ice is detected by the control software, allowing both noninvasive detection of the nucleation event for quality control purposes and the potential to modify the cooling profile following ice nucleation in an active manner. When processing 200 mL of ELS in the VIA Freeze-viabilities at 93.4% ± 7.4%, viable cell numbers at 14.3 ± 1.7 million nuclei/mL alginate, and protein secretion at 10.5 ± 1.7

  14. The large conductance calcium-activated K(+) channel interacts with the small GTPase Rab11b.

    PubMed

    Sokolowski, Sophia; Harvey, Margaret; Sakai, Yoshihisa; Jordan, Amy; Sokolowski, Bernd

    2012-09-21

    The transduction of sound by the receptor or hair cells of the cochlea leads to the activation of ion channels found in the basal and lateral regions of these cells. Thus, the processing of these transduced signals to the central nervous system is tied to the regulation of baso-lateral ion channels. The large conductance calcium-activated potassium or BK channel was revealed to interact with the small GTPase, Rab11b, which is one of many Rabs found in various endosomal pathways. Immunoelectron microscopy showed the colocalization of these two proteins in receptor cells and auditory neurons. Using Chinese hamster ovary cells as a heterologous expression system, Rab11b increased or decreased BK expression, depending on the overexpression or RNAi knockdown of Rab, respectively. Additional mutation analyses, using a yeast two-hybrid assay, suggested that this GTPase moderately interacts within a region of BK exclusive of the N- or C-terminal tails. These data suggest that this small GTPase regulates BK in a slow recycling process through the endocytic compartment and to the plasmalemma.

  15. The large conductance calcium-activated K+ channel interacts with the small GTPase Rab11b

    PubMed Central

    Sokolowski, Sophia; Harvey, Margaret; Sakai, Yoshihisa; Jordan, Amy; Sokolowski, Bernd

    2012-01-01

    The transduction of sound by the receptor or hair cells of the cochlea leads to the activation of ion channels found in the basal and lateral regions of these cells. Thus, the processing of these transduced signals to the central nervous system is tied to the regulation of baso-lateral ion channels. The large conductance calcium-activated potassium or BK channel was revealed to interact with the small GTPase, Rab11b, which is one of many Rabs found in various endosomal pathways. Immunoelectron microscopy showed the colocalization of these two proteins in receptor cells and auditory neurons. Using Chinese hamster ovary cells as a heterologous expression system, Rab11b increased or decreased BK expression, depending on the overexpression or RNAi knockdown of Rab, respectively. Additional mutation analyses, using a yeast two-hybrid assay, suggested that this GTPase moderately interacts within a region of BK exclusive of the N- or C-terminal tails. These data suggest that this small GTPase regulates BK in a slow recycling process through the endocytic compartment and to the plasmalemma. PMID:22935415

  16. Active alignment and vibration control system for a large airborne optical system

    NASA Astrophysics Data System (ADS)

    Kienholz, David A.

    2000-04-01

    Airborne optical or electro-optical systems may be too large for all elements to be mounted on a single integrating structure, other than the aircraft fuselage itself. An active system must then be used to maintain the required alignment between elements. However the various smaller integrating structures (benches) must still be isolated from high- frequency airframe disturbances that could excite resonances outside the bandwidth of the alignment control system. The combined active alignment and vibration isolation functions must be performed by flight-weight components, which may have to operate in vacuum. A testbed system developed for the Air Force Airborne Laser program is described. The payload, a full-scale 1650-lb simulated bench, is mounted in six degrees- of-freedom to a vibrating platform by a set of isolator- actuators. The mounts utilize a combination of pneumatics and magnetics to perform the dual functions of low-frequency alignment and high-frequency isolation. Test results are given and future directions for development are described.

  17. Antitumor activity of fucoidan against diffuse large B cell lymphoma in vitro and in vivo.

    PubMed

    Yang, Guang; Zhang, Qianqiao; Kong, Yuanyuan; Xie, Bingqian; Gao, Minjie; Tao, Yi; Xu, Hongwei; Zhan, Fenghuang; Dai, Bojie; Shi, Jumei; Wu, Xiaosong

    2015-11-01

    Fucoidan is one of the major sulfated polysaccharides isolated from brown seaweeds. In this study, we determined the anti-cancer activity of fucoidan on diffuse large B cell lymphoma (DLBCL) cells both in vitro and in vivo. Fucoidan inhibited the growth of DLBCL cells in a dose- and time-dependent manner, and fucoidan treatment provoked G0/G1 cell cycle arrest, which was accompanied by p21 up-regulation and cyclin D1, Cdk4, and Cdk6 down-regulation. Fucoidan also induced caspase-dependent cell apoptosis in DLBCL cell lines and primary DLBCL cell. In addition, fucoidan treatment caused the loss of mitochondrial membrane potential and the release of cytochrome c and apoptosis-inducing factor from the mitochondria into the cytosol. Fucoidan also potentiated the activities of carfilzomib in killing DLBCL cells. Oral administration of fucoidan effectively inhibited tumor growth in xenograft mouse models. Our findings reveal the novel function of fucoidan as an anti-DLBCL agent, which can be used in the clinical treatment of DLBCL.

  18. Large Conductance Ca2+-Activated K+ Channels Modulate Uterine α1-Adrenergic Sensitivity in Ovine Pregnancy

    PubMed Central

    Hynan, Linda S.; Liu, Xiao-tie; Roy, Timothy

    2014-01-01

    The uteroplacental vasculature is refractory to α-adrenergic stimulation, and large conductance Ca2+-activated K+ channels (BKCa) may contribute. We examined the effects of uterine artery (UA) BKCa inhibition with tetraethylammonium (TEA) on hemodynamic responses to phenylephrine (PE) at 101 to 117 days and 135 to 147 days of ovine gestation, obtaining dose responses for mean arterial pressure (MAP), heart rate (HR), and uteroplacental blood flow (UPBF) and vascular resistance (UPVR) before and during UA TEA infusions. The UA α1-adrenergic receptors (α1-ARs) were assessed. The PE increased MAP and UPVR and decreased HR and UPBF dose dependently at both gestations (P < .001, analysis of variance). The %▵MAP was less at 135 to 147 days before and during TEA infusions (P ≤ .008); however, responses during TEA were greater (P ≤ .002). The PE increased %▵UPVR>>%▵MAP, thus %▵UPBF fell. The TEA enhanced PE-mediated increases in %▵UPVR at 135 to 147 days (P ≤ .03). The UA α1-AR expression was unchanged in pregnancy. Uterine vascular responses to PE exceed systemic vascular responses throughout pregnancy and are attenuated by BKCa activation, suggesting BKCa protect UPBF. PMID:24026311

  19. Anatomical connectivity and the resting state activity of large cortical networks

    PubMed Central

    Pinotsis, D.A.; Hansen, E.; Friston, K.J.; Jirsa, V.K.

    2013-01-01

    This paper uses mathematical modelling and simulations to explore the dynamics that emerge in large scale cortical networks, with a particular focus on the topological properties of the structural connectivity and its relationship to functional connectivity. We exploit realistic anatomical connectivity matrices (from diffusion spectrum imaging) and investigate their capacity to generate various types of resting state activity. In particular, we study emergent patterns of activity for realistic connectivity configurations together with approximations formulated in terms of neural mass or field models. We find that homogenous connectivity matrices, of the sort of assumed in certain neural field models give rise to damped spatially periodic modes, while more localised modes reflect heterogeneous coupling topologies. When simulating resting state fluctuations under realistic connectivity, we find no evidence for a spectrum of spatially periodic patterns, even when grouping together cortical nodes into communities, using graph theory. We conclude that neural field models with translationally invariant connectivity may be best applied at the mesoscopic scale and that more general models of cortical networks that embed local neural fields, may provide appropriate models of macroscopic cortical dynamics over the whole brain. PMID:23085498

  20. The influence of lightning activity and anthropogenic factors on large-scale characteristics of natural fires

    NASA Astrophysics Data System (ADS)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.

    2017-01-01

    A module for simulating of natural fires (NFs) in the climate model of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), is extended with respect to the influence of lightning activity and population density on the ignition frequency and fire suppression. The IAP RAS CM is used to perform numerical experiments in accordance with the conditions of the project that intercompares climate models, CMIP5 (Coupled Models Intercomparison Project, phase 5). The frequency of lightning flashes was assigned in accordance with the LIS/OTD satellite data. In the calculations performed, anthropogenic ignitions play an important role in NF occurrences, except for regions at subpolar latitudes and, to a lesser degree, tropical and subtropical regions. Taking into account the dependence of fire frequency on lightning activity and population density intensifies the influence of characteristics of natural fires on the climate changes in tropics and subtropics as compared to the version of the IAP RAS CM that does not take the influence of ignition sources on the large-scale characteristics of NFs into consideration.

  1. The Large Conductance, Calcium-activated K+ (BK) Channel is regulated by Cysteine String Protein

    PubMed Central

    Kyle, Barry D.; Ahrendt, Eva; Braun, Andrew P.; Braun, Janice E. A.

    2013-01-01

    Large-conductance, calcium-activated-K+ (BK) channels are widely distributed throughout the nervous system, where they regulate action potential duration and firing frequency, along with presynaptic neurotransmitter release. Our recent efforts to identify chaperones that target neuronal ion channels have revealed cysteine string protein (CSPα) as a key regulator of BK channel expression and current density. CSPα is a vesicle-associated protein and mutations in CSPα cause the hereditary neurodegenerative disorder, adult-onset autosomal dominant neuronal ceroid lipofuscinosis (ANCL). CSPα null mice show 2.5 fold higher BK channel expression compared to wild type mice, which is not seen with other neuronal channels (i.e. Cav2.2, Kv1.1 and Kv1.2). Furthermore, mutations in either CSPα's J domain or cysteine string region markedly increase BK expression and current amplitude. We conclude that CSPα acts to regulate BK channel expression, and consequently CSPα-associated changes in BK activity may contribute to the pathogenesis of neurodegenerative disorders, such as ANCL. PMID:23945775

  2. Measurement of fumonisins in corn with a fiber optic fluoroimmunosensor

    NASA Astrophysics Data System (ADS)

    Thompson, Vicki S.; Maragos, Chris M.

    1997-05-01

    A fiber-optic immunosensor was used to determine concentrations of the mycotoxin fumonisin B1(FB1) in both spiked and naturally contaminated corn samples. Samples were extracted with a mixture of methanol/water. Two methods were used to prepare the methanolic corn extracts before introduction to the immunosensor: (1) simple dilution of the methanolic corn extract; or (2) affinity column cleanup. The sensor displayed an IC50 of 70 ng FB1/mL when toxin was introduced in phosphate buffered saline. Simple dilution of methanolic corn extracts yielded an assay with an IC50 equivalent to 25 (mu) gFB1/g corn and a limit of detection of 3.2 (mu) g/g corn, while affinity cleanup of corn extracts yielded an assay with an IC50 of 5 (mu) gFB1/g corn and a limit of detection of 0.4 (mu) gFB1/g corn. The difference in sensitivity between the two cleanup techniques was due to concentration of fumonisins obtained from the affinity cleanup procedure. Naturally contaminated corn samples were also analyzed after either simple dilution or affinity column cleanup. For comparison the naturally contaminated corn samples were analyzed with an HPLC method after isolation of the fumonisins with strong anion exchange (SAX) solid phase extraction cartridges. The SAX/HPLC method and the immunosensor method agreed well except when large amounts of other fumonisins (i.e. fumonisin B2) were present. This was due in part to the cross-reactivity of the monoclonal antibody with other fumonisins. The immunosensor has the potential to screen individual corn samples for fumonisins within six minutes, and is among the fastest of the currently available FB1 detection methods.

  3. The large conductance calcium-activated potassium channel affects extrinsic and intrinsic mechanisms of apoptosis.

    PubMed

    Sakai, Yoshihisa; Sokolowski, Bernd

    2015-05-01

    The large-conductance calcium-activated K(+) or BK channel underlies electrical signals in a number of different cell types. Studies show that BK activity can also serve to regulate cellular homeostasis by protecting cells from apoptosis resulting from events such as ischemia. Recent coimmunoprecipitation studies, combined with mass spectrometry, suggest putative protein partners that interact with BK to regulate intrinsic and extrinsic apoptotic pathways. This study tests two of those partners to determine the effects on these two signaling pathways. Through reciprocal coimmunoprecipitation (coIP) experiments, we show that BK interacts with p53 and fas-associated protein with death domain (FADD) in mouse brain and when overexpressed in a heterologous expression system, such as HEK293 cells. Moreover, coIP experiments with N- and C-terminal fragments reveal that FADD interacts with the C-terminus of BK, whereas p53 interacts with either the N- or the C-terminus. Immunolocalization studies show that BK colocalizes with p53 and FADD in the mitochondrion and plasmalemma, respectively. HEK cells that stably express BK are more resistant to apoptosis when p53 or FADD is overexpressed or when their intrinsic and extrinsic pathways are stimulated via mitomycin C or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), respectively. Moreover, when stimulating with TRAIL, caspase-8 activation decreases in BK-expressing cells. These data suggest that BK is part of a larger complex of proteins that protects against apoptosis by interacting with proapoptotic proteins, such as p53 and FADD. © 2015 Wiley Periodicals, Inc.

  4. Highly Active and Stable Large Catalase Isolated from a Hydrocarbon Degrading Aspergillus terreus MTCC 6324

    PubMed Central

    Vatsyayan, Preety; Goswami, Pranab

    2016-01-01

    A hydrocarbon degrading Aspergillus terreus MTCC 6324 produces a high level of extremely active and stable cellular large catalase (CAT) during growth on n-hexadecane to combat the oxidative stress caused by the hydrocarbon degrading metabolic machinery inside the cell. A 160-fold purification with specific activity of around 66 × 105 U mg−1 protein was achieved. The native protein molecular mass was 368 ± 5 kDa with subunit molecular mass of nearly 90 kDa, which indicates that the native CAT protein is a homotetramer. The isoelectric pH (pI) of the purified CAT was 4.2. BLAST aligned peptide mass fragments of CAT protein showed its highest similarity with the catalase B protein from other fungal sources. CAT was active in a broad range of pH 4 to 12 and temperature 25°C to 90°C. The catalytic efficiency (Kcat/Km) of 4.7 × 108 M−1 s−1 within the studied substrate range and alkaline pH stability (half-life, t1/2 at pH 12~15 months) of CAT are considerably higher than most of the extensively studied catalases from different sources. The storage stability (t1/2) of CAT at physiological pH 7.5 and 4°C was nearly 30 months. The haem was identified as haem b by electrospray ionization tandem mass spectroscopy (ESI-MS/MS). PMID:27057351

  5. Caffeine-activated large-conductance plasma membrane cation channels in cardiac myocytes: characteristics and significance.

    PubMed

    Zhang, Yu-An; Tuft, Richard A; Lifshitz, Lawrence M; Fogarty, Kevin E; Singer, Joshua J; Zou, Hui

    2007-10-01

    Caffeine-activated, large-conductance, nonselective cation channels (LCCs) have been found in the plasma membrane of isolated cardiac myocytes in several species. However, little is known about the effects of opening these channels. To examine such effects and to further understand the caffeine-activation mechanism, we carried out studies using whole-cell patch-clamp techniques with freshly isolated cardiac myocytes from rats and mice. Unlike previous studies, thapsigargin was used so that both the effect of opening LCCs and the action of caffeine were independent of Ca(2+) release from intracellular stores. These Ca(2+)-permeable LCCs were found in a majority of the cells from atria and ventricles, with a conductance of approximately 370 pS in rat atria. Caffeine and all its direct metabolic products (theophylline, theobromine, and paraxanthine) activated the channel, while isocaffeine did not. Although they share some similarities with ryanodine receptors (RyRs, the openings of which give rise to Ca(2+) sparks), LCCs also showed some different characteristics. With simultaneous Ca(2+) imaging and current recording, the localized fluorescence increase due to Ca(2+) entry through a single opening of an LCC (SCCaFT) was detected. When membrane potential, instead of current, was recorded, SCCaFT-like fluorescence transients (indicating single LCC openings) were found to accompany membrane depolarizations. To our knowledge, this is the first report directly linking membrane potential changes to a single opening of an ion channel. Moreover, these events in cardiac cells suggest a possible additional mechanism by which caffeine and theophylline contribute to the generation of cardiac arrhythmias.

  6. Pituitary adenylate cyclase activating polypeptide (PACAP) dilates cerebellar arteries through activation of large-conductance Ca(2+)-activated (BK) and ATP-sensitive (K ATP) K (+) channels.

    PubMed

    Koide, Masayo; Syed, Arsalan U; Braas, Karen M; May, Victor; Wellman, George C

    2014-11-01

    Pituitary adenylate cyclase activating polypeptide (PACAP) is a potent vasodilator of numerous vascular beds, including cerebral arteries. Although PACAP-induced cerebral artery dilation is suggested to be cyclic AMP (cAMP)-dependent, the downstream intracellular signaling pathways are still not fully understood. In this study, we examined the role of smooth muscle K(+) channels and hypothesized that PACAP-mediated increases in cAMP levels and protein kinase A (PKA) activity result in the coordinate activation of ATP-sensitive K(+) (KATP) and large-conductance Ca(2+)-activated K(+) (BK) channels for cerebral artery dilation. Using patch-clamp electrophysiology, we observed that PACAP enhanced whole-cell KATP channel activity and transient BK channel currents in freshly isolated rat cerebellar artery myocytes. The increased frequency of transient BK currents following PACAP treatment is indicative of increased intracellular Ca(2+) release events termed Ca(2+) sparks. Consistent with the electrophysiology data, the PACAP-induced vasodilations of cannulated cerebellar artery preparations were attenuated by approximately 50 % in the presence of glibenclamide (a KATP channel blocker) or paxilline (a BK channel blocker). Further, in the presence of both blockers, PACAP failed to cause vasodilation. In conclusion, our results indicate that PACAP causes cerebellar artery dilation through two mechanisms: (1) KATP channel activation and (2) enhanced BK channel activity, likely through increased Ca(2+) spark frequency.

  7. RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY

    SciTech Connect

    Fu, Hai; Myers, A. D.; Djorgovski, S. G.; Yan, Lin; Wrobel, J. M.; Stockton, A.

    2015-01-20

    Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active galactic nuclei (AGNs) among galaxy mergers. However, determining the fraction requires a statistical sample of binaries. We have identified kiloparsec-scale binary AGNs directly from high-resolution radio imaging. Inside the 92 deg{sup 2} covered by the high-resolution Very Large Array survey of the Sloan Digital Sky Survey (SDSS) Stripe 82 field, we identified 22 grade A and 30 grade B candidates of binary radio AGNs with angular separations less than 5'' (10 kpc at z = 0.1). Eight of the candidates have optical spectra for both components from the SDSS spectroscopic surveys and our Keck program. Two grade B candidates are projected pairs, but the remaining six candidates are all compelling cases of binary AGNs based on either emission line ratios or the excess in radio power compared to the Hα-traced star formation rate. Only two of the six binaries were previously discovered by an optical spectroscopic search. Based on these results, we estimate that ∼60% of our binary candidates would be confirmed once we obtain complete spectroscopic information. We conclude that wide-area high-resolution radio surveys offer an efficient method to identify large samples of binary AGNs. These radio-selected binary AGNs complement binaries identified at other wavelengths and are useful for understanding the triggering mechanisms of black hole accretion.

  8. Selectivity filter gating in large-conductance Ca(2+)-activated K+ channels.

    PubMed

    Thompson, Jill; Begenisich, Ted

    2012-03-01

    Membrane voltage controls the passage of ions through voltage-gated K (K(v)) channels, and many studies have demonstrated that this is accomplished by a physical gate located at the cytoplasmic end of the pore. Critical to this determination were the findings that quaternary ammonium ions and certain peptides have access to their internal pore-blocking sites only when the channel gates are open, and that large blocking ions interfere with channel closing. Although an intracellular location for the physical gate of K(v) channels is well established, it is not clear if such a cytoplasmic gate exists in all K(+) channels. Some studies on large-conductance, voltage- and Ca(2+)-activated K(+) (BK) channels suggest a cytoplasmic location for the gate, but other findings question this conclusion and, instead, support the concept that BK channels are gated by the pore selectivity filter. If the BK channel is gated by the selectivity filter, the interactions between the blocking ions and channel gating should be influenced by the permeant ion. Thus, we tested tetrabutyl ammonium (TBA) and the Shaker "ball" peptide (BP) on BK channels with either K(+) or Rb(+) as the permeant ion. When tested in K(+) solutions, both TBA and the BP acted as open-channel blockers of BK channels, and the BP interfered with channel closing. In contrast, when Rb(+) replaced K(+) as the permeant ion, TBA and the BP blocked both closed and open BK channels, and the BP no longer interfered with channel closing. We also tested the cytoplasmically gated Shaker K channels and found the opposite behavior: the interactions of TBA and the BP with these K(v) channels were independent of the permeant ion. Our results add significantly to the evidence against a cytoplasmic gate in BK channels and represent a positive test for selectivity filter gating.

  9. Radio-selected Binary Active Galactic Nuclei from the Very Large Array Stripe 82 Survey

    NASA Astrophysics Data System (ADS)

    Fu, Hai; Myers, A. D.; Djorgovski, S. G.; Yan, Lin; Wrobel, J. M.; Stockton, A.

    2015-01-01

    Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active galactic nuclei (AGNs) among galaxy mergers. However, determining the fraction requires a statistical sample of binaries. We have identified kiloparsec-scale binary AGNs directly from high-resolution radio imaging. Inside the 92 deg2 covered by the high-resolution Very Large Array survey of the Sloan Digital Sky Survey (SDSS) Stripe 82 field, we identified 22 grade A and 30 grade B candidates of binary radio AGNs with angular separations less than 5'' (10 kpc at z = 0.1). Eight of the candidates have optical spectra for both components from the SDSS spectroscopic surveys and our Keck program. Two grade B candidates are projected pairs, but the remaining six candidates are all compelling cases of binary AGNs based on either emission line ratios or the excess in radio power compared to the Hα-traced star formation rate. Only two of the six binaries were previously discovered by an optical spectroscopic search. Based on these results, we estimate that ~60% of our binary candidates would be confirmed once we obtain complete spectroscopic information. We conclude that wide-area high-resolution radio surveys offer an efficient method to identify large samples of binary AGNs. These radio-selected binary AGNs complement binaries identified at other wavelengths and are useful for understanding the triggering mechanisms of black hole accretion. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  10. Selectivity filter gating in large-conductance Ca2+-activated K+ channels

    PubMed Central

    Thompson, Jill

    2012-01-01

    Membrane voltage controls the passage of ions through voltage-gated K (Kv) channels, and many studies have demonstrated that this is accomplished by a physical gate located at the cytoplasmic end of the pore. Critical to this determination were the findings that quaternary ammonium ions and certain peptides have access to their internal pore-blocking sites only when the channel gates are open, and that large blocking ions interfere with channel closing. Although an intracellular location for the physical gate of Kv channels is well established, it is not clear if such a cytoplasmic gate exists in all K+ channels. Some studies on large-conductance, voltage- and Ca2+-activated K+ (BK) channels suggest a cytoplasmic location for the gate, but other findings question this conclusion and, instead, support the concept that BK channels are gated by the pore selectivity filter. If the BK channel is gated by the selectivity filter, the interactions between the blocking ions and channel gating should be influenced by the permeant ion. Thus, we tested tetrabutyl ammonium (TBA) and the Shaker “ball” peptide (BP) on BK channels with either K+ or Rb+ as the permeant ion. When tested in K+ solutions, both TBA and the BP acted as open-channel blockers of BK channels, and the BP interfered with channel closing. In contrast, when Rb+ replaced K+ as the permeant ion, TBA and the BP blocked both closed and open BK channels, and the BP no longer interfered with channel closing. We also tested the cytoplasmically gated Shaker K channels and found the opposite behavior: the interactions of TBA and the BP with these Kv channels were independent of the permeant ion. Our results add significantly to the evidence against a cytoplasmic gate in BK channels and represent a positive test for selectivity filter gating. PMID:22371364

  11. A Case Study of How a Large Multilevel EFL Writing Class Experiences and Perceives Multiple Interaction Activities

    ERIC Educational Resources Information Center

    Lin, Hsien-Chuan

    2009-01-01

    The purpose of this study was to examine students' experiences and perceptions of multiple interaction activities (self-directed, peer, and teacher feedback) implemented in a large multilevel EFL writing class in one private technological university in the southern part of Taiwan. Large size writing classes, quite common in private institutions of…

  12. A Case Study of How a Large Multilevel EFL Writing Class Experiences and Perceives Multiple Interaction Activities

    ERIC Educational Resources Information Center

    Lin, Hsien-Chuan

    2009-01-01

    The purpose of this study was to examine students' experiences and perceptions of multiple interaction activities (self-directed, peer, and teacher feedback) implemented in a large multilevel EFL writing class in one private technological university in the southern part of Taiwan. Large size writing classes, quite common in private institutions of…

  13. Squeezed pulsed light from a fiber ring interferometer

    NASA Technical Reports Server (NTRS)

    Bergman, K.; Haus, H. A.

    1992-01-01

    Observation of squeezed noise, 5 +/- 0.3 dB below the shot noise level, generated with pulses in a fiber ring interferometer is reported. The interferometric geometry is used to separate the pump pulse from the squeezed vacuum radiation. A portion of the pump is reused as the local oscillator in a homodyne detection. The pump fluctuations are successfully subtracted and shot noise limited performance is achieved at low frequencies (35-85 KHz). A possible utilization of the generated squeezed vacuum in improving a fiber gyro's signal to noise ratio is discussed.

  14. A Large-N Mixed Sensor Active + Passive Seismic Array near Sweetwater, TX

    NASA Astrophysics Data System (ADS)

    Barklage, M.; Hollis, D.; Gridley, J. M.; Woodward, R.; Spriggs, N.

    2014-12-01

    A collaborative high-density seismic survey using broadband and short period seismic sensors was conducted March 7 - April 30, 2014 near Sweetwater, TX. The objective of the survey was to use a combination of controlled source shot slices and passive seismic recordings recorded by multiple types of sensors with different bandwidths and sensitivities to image the subsurface. The broadband component of the survey consisted of 25 continuously recording seismic stations comprised of 20 Trillium Compact Posthole sensors from Nanometrics and 5 Polar Trillium 120PHQs from the IRIS/PASSCAL Instrument Center (PIC). The broadband stations also utilized 25 Centaur digitizers from Nanometrics as well as 25 polar quick deploy enclosures from the PIC. The broadband array was designed to maximize horizontal traveling seismic energy for surface wave analysis over the primary target area with sufficient offset for imaging objectives at depth. The short period component of the survey consisted of 2639 receiver locations using Zland nodes from NodalSeismic. The nodes are further divided into 3 sub-arrays: 1) outlier array 2) active source array 3) backbone array. The outlier array consisted of 25 continuously recording nodes distributed around the edge of the survey at a distance of ~5 km from the survey boundary, and provided valuable constraints to passive data analysis techniques at the edge of the survey boundary. The active source patch consisted of densely spaced nodes that were designed to record signals from a Vibroseis source truck for active source reflection processing and imaging. The backbone array consisted of 292 nodes that covered the entirety of the survey area to maximize the value of the passive data analysis. By utilizing continuous recording and smartly designed arrays for measuring local and regional earthquakes we can incorporate velocity information derived from passive data analysis into the active source processing workflow to produce a superior subsurface

  15. Gaining A Geological Perspective Through Active Learning in the Large Lecture Classroom

    NASA Astrophysics Data System (ADS)

    Kapp, J. L.; Richardson, R. M.; Slater, S. J.

    2008-12-01

    NATS 101 A Geological Perspective is a general education course taken by non science majors. We offer 600 seats per semester, with four large lecture sections taught by different faculty members. In the past we have offered optional once a week study groups taught by graduate teaching assistants. Students often feel overwhelmed by the science and associated jargon, and many are prone to skipping lectures altogether. Optional study groups are only attended by ~50% of the students. Faculty members find the class to be a lot of work, mainly due to the grading it generates. Activities given in lecture are often short multiple choice or true false assignments, limiting the depth of understanding we can evaluate. Our students often lack math and critical thinking skills, and we spend a lot of time in lecture reintroducing ideas students should have already gotten from the text. In summer 2007 we were funded to redesign the course. Our goals were to 1) cut the cost of running the course, and 2) improve student learning. Under our redesign optional study groups were replaced by once a week mandatory break out sessions where students complete activities that have been introduced in lecture. Break out sessions substitute for one hour of lecture, and are run by undergraduate preceptors and graduate teaching assistants (GTAs). During the lecture period, lectures themselves are brief with a large portion of the class devoted to active learning in small groups. Weekly reading quizzes are submitted via the online course management system. Break out sessions allow students to spend more time interacting with their fellow students, undergraduate preceptors, and GTAs. They get one on one help in break out sessions on assignments designed to enhance the lecture material. The active lecture format means less of their time is devoted to listening passively to a lecture, and more time is spent peer learning an interacting with the instructor. Completing quizzes online allows students

  16. Anthropometric measures, physical activity and risk of glioma and meningioma in a large prospective cohort study

    PubMed Central

    Michaud, Dominique S.; Bové, Gerald; Gallo, Valentina; Schlehofer, Brigitte; Tjønneland, Anne; Olsen, Anja; Overvad, Kim; Dahm, Christina C.; Teucher, Brigit; Boeing, Heiner; Steffen, Annika; Trichopoulou, Antonia; Bamia, Christina; Kyrozis, Andreas; Sacerdote, Carlotta; Agnoli, Claudia; Palli, Domenico; Tumino, Rosario; Mattiello, Amalia; Bueno-de-Mesquita, H. Bas; Peeters, Petra H. M.; May, Anne M.; Barricarte, Aurelio; Chirlaque, Maria-Dolores; Dorronsoro, Miren; Sánchez, Maria José; Rodríguez, Laudina; Duell, Eric J; Hallmans, Göran; Melin, Beatrice S.; Manjer, Jonas; Borgquist, Signe; Khaw, Kay-Tee; Wareham, Nick; Allen, Naomi E.; Travis, Ruth C.; Romieu, Isabelle; Vineis, Paolo; Riboli, Elio

    2011-01-01

    Body fatness has been associated with increased risk of a number of hormone-dependent cancers. Recent studies suggest that body mass index may be related to meningiomas, which are more common in women than men, and for which estrogens are believed to play a role. Using data from a large European propective cohort, 203 incident cases of meningioma and 340 cases of glioma were included in the analysis for measures of body fat, height, and physical activity among 380,775 participants. All analyses were conducted using Cox proportional hazards model and controlling for age, sex, country and education. A 71% increase in risk of meningioma was observed among men and women in the top quartile of waist circumference (HR = 1.71, 95% CI = 1.08–2.73, p-trend=0.01). A positive association was also observed for body mass index and meningioma (HR = 1.48, 95% CI = 0.98–2.23, for BMI ≥30 compared with a BMI of 20–24.9, p trend=0.05). An association with height and meningioma was also suggestive (HR = 1.24, 95% 0.96–1.51, for each 10cm increase). In contrast, no associations were observed for height and different measures of body fat and risk of glioma. Physical activity was not related to either type of brain tumors. Results from this study support an increase in risk of meningioma with higher body fatness among both men and women. No association was observed between anthropometric measures and risk of glioma. PMID:21685234

  17. Rationally designed BCL6 inhibitors target activated B cell diffuse large B cell lymphoma.

    PubMed

    Cardenas, Mariano G; Yu, Wenbo; Beguelin, Wendy; Teater, Matthew R; Geng, Huimin; Goldstein, Rebecca L; Oswald, Erin; Hatzi, Katerina; Yang, Shao-Ning; Cohen, Joanna; Shaknovich, Rita; Vanommeslaeghe, Kenno; Cheng, Huimin; Liang, Dongdong; Cho, Hyo Je; Abbott, Joshua; Tam, Wayne; Du, Wei; Leonard, John P; Elemento, Olivier; Cerchietti, Leandro; Cierpicki, Tomasz; Xue, Fengtian; MacKerell, Alexander D; Melnick, Ari M

    2016-09-01

    Diffuse large B cell lymphomas (DLBCLs) arise from proliferating B cells transiting different stages of the germinal center reaction. In activated B cell DLBCLs (ABC-DLBCLs), a class of DLBCLs that respond poorly to current therapies, chromosomal translocations and amplification lead to constitutive expression of the B cell lymphoma 6 (BCL6) oncogene. The role of BCL6 in maintaining these lymphomas has not been investigated. Here, we designed small-molecule inhibitors that display higher affinity for BCL6 than its endogenous corepressor ligands to evaluate their therapeutic efficacy for targeting ABC-DLBCL. We used an in silico drug design functional-group mapping approach called SILCS to create a specific BCL6 inhibitor called FX1 that has 10-fold greater potency than endogenous corepressors and binds an essential region of the BCL6 lateral groove. FX1 disrupted formation of the BCL6 repression complex, reactivated BCL6 target genes, and mimicked the phenotype of mice engineered to express BCL6 with corepressor binding site mutations. Low doses of FX1 induced regression of established tumors in mice bearing DLBCL xenografts. Furthermore, FX1 suppressed ABC-DLBCL cells in vitro and in vivo, as well as primary human ABC-DLBCL specimens ex vivo. These findings indicate that ABC-DLBCL is a BCL6-dependent disease that can be targeted by rationally designed inhibitors that exceed the binding affinity of natural BCL6 ligands.

  18. Active power control of solar PV generation for large interconnection frequency regulation and oscillation damping

    SciTech Connect

    Liu, Yong; Zhu, Lin; Zhan, Lingwei; Gracia, Jose R.; King, Thomas Jr.; Liu, Yilu

    2015-06-23

    Because of zero greenhouse gas emission and decreased manufacture cost, solar photovoltaic (PV) generation is expected to account for a significant portion of future power grid generation portfolio. Because it is indirectly connected to the power grid via power electronic devices, solar PV generation system is fully decoupled from the power grid, which will influence the interconnected power grid dynamic characteristics as a result. In this study, the impact of solar PV penetration on large interconnected power system frequency response and inter-area oscillation is evaluated, taking the United States Eastern Interconnection (EI) as an example. Furthermore, based on the constructed solar PV electrical control model with additional active power control loops, the potential contributions of solar PV generation to power system frequency regulation and oscillation damping are examined. The advantages of solar PV frequency support over that of wind generator are also discussed. Finally, simulation results demonstrate that solar PV generations can effectively work as ‘actuators’ in alleviating the negative impacts they bring about.

  19. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

    SciTech Connect

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R.; Yakobson, Boris I.; McCarty, Kevin F.; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S.

    2016-02-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional 'surface-limited' growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to -100 meV at a displacement field of 0.9 V nm-1.

  20. Promoting active learning using audience response system in large bioscience classes.

    PubMed

    Efstathiou, Nikolaos; Bailey, Cara

    2012-01-01

    This paper considers the challenges of bioscience teaching and learning in pre-registration nurse education. Effective learning requires active student participation which is problematic when teaching large groups of students. New technologies, such as the audience response system (ARS), have been introduced to increase student participation and support them in the understanding of complex bioscience concepts. Within one university department, an evaluation was undertaken to identify the perceptions of pre-registration nurse students on the use of ARS in the teaching and learning of bioscience. Our findings concur with others that ARS increases student participation and aids in identifying misconceptions and in correcting them. Students found ARS very useful and wanted ARS to be used in additional modules too. Although ARS did not seem to motivate students to study adequately before attending the relevant sessions, it increased discussion among students and awareness of their level of knowledge compared to their peers. Further research is required to identify the effectiveness of ARS in the teaching and learning of bioscience and its impact on the performance of the students in their final assessments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Active edge control in the precessions polishing process for manufacturing large mirror segments

    NASA Astrophysics Data System (ADS)

    Li, Hongyu; Zhang, Wei; Walker, David; Yu, Gouyo

    2014-09-01

    The segmentation of the primary mirror is the only promising solution for building the next generation of ground telescopes. However, manufacturing segmented mirrors presents its own challenges. The edge mis-figure impacts directly on the telescope's scientific output. The `Edge effect' significantly dominates the polishing precision. Therefore, the edge control is regarded as one of the most difficult technical issues in the segment production that needs to be addressed urgently. This paper reports an active edge control technique for the mirror segments fabrication using the Precession's polishing technique. The strategy in this technique requires that the large spot be selected on the bulk area for fast polishing, and the small spot is used for edge figuring. This can be performed by tool lift and optimizing the dell time to compensate for non-uniform material removal at the edge zone. This requires accurate and stable edge tool influence functions. To obtain the full tool influence function at the edge, we have demonstrated in previous work a novel hybrid-measurement method which uses both simultaneous phase interferometry and profilometry. In this paper, the edge effect under `Bonnet tool' polishing is investigated. The pressure distribution is analyzed by means of finite element analysis (FEA). According to the `Preston' equation, the shape of the edge tool influence functions is predicted. With this help, the multiple process parameters at the edge zone are optimized. This is demonstrated on a 200mm crosscorners hexagonal part with a result of PV less than 200nm for entire surface.

  2. Active power control of solar PV generation for large interconnection frequency regulation and oscillation damping

    DOE PAGES

    Liu, Yong; Zhu, Lin; Zhan, Lingwei; ...

    2015-06-23

    Because of zero greenhouse gas emission and decreased manufacture cost, solar photovoltaic (PV) generation is expected to account for a significant portion of future power grid generation portfolio. Because it is indirectly connected to the power grid via power electronic devices, solar PV generation system is fully decoupled from the power grid, which will influence the interconnected power grid dynamic characteristics as a result. In this study, the impact of solar PV penetration on large interconnected power system frequency response and inter-area oscillation is evaluated, taking the United States Eastern Interconnection (EI) as an example. Furthermore, based on the constructedmore » solar PV electrical control model with additional active power control loops, the potential contributions of solar PV generation to power system frequency regulation and oscillation damping are examined. The advantages of solar PV frequency support over that of wind generator are also discussed. Finally, simulation results demonstrate that solar PV generations can effectively work as ‘actuators’ in alleviating the negative impacts they bring about.« less

  3. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene.

    PubMed

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R; Yakobson, Boris I; McCarty, Kevin F; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S

    2016-05-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional 'surface-limited' growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 10(4), and a tunable bandgap up to ∼100 meV at a displacement field of 0.9 V nm(-1).

  4. DYNAMICS OF LARGE FRAGMENTS IN THE TAIL OF ACTIVE ASTEROID P/2010 A2

    SciTech Connect

    Agarwal, Jessica; Jewitt, David; Weaver, Harold

    2013-05-20

    We examine the motions of large fragments at the head of the dust tail of the active asteroid P/2010 A2. In previous work, we showed that these fragments were ejected from the primary nucleus in early 2009, either following a hypervelocity impact or by rotationally induced breakup. Here, we follow their positions through a series of Hubble Space Telescope images taken during the first half of 2010. The orbital evolution of each fragment allows us to constrain its velocity relative to the main nucleus after leaving its sphere of gravitational influence. We find that the fragments constituting a prominent X-shaped tail feature were emitted in a direction opposite to the motion of the asteroid and toward the south of its orbital plane. Derived emission velocities of these primary fragments range between 0.02 and 0.3 m s{sup -1}, comparable to the {approx}0.08 m s{sup -1} gravitational escape speed from the nucleus. Their sizes are on the order of decimeters or larger. We obtain the best fits to our data with ejection velocity vectors lying in a plane that includes the nucleus. This may suggest that the cause of the disruption of P/2010 A2 is rotational breakup.

  5. Hurricane activity and the large-scale pattern of spread of an invasive plant species.

    PubMed

    Bhattarai, Ganesh P; Cronin, James T

    2014-01-01

    Disturbances are a primary facilitator of the growth and spread of invasive species. However, the effects of large-scale disturbances, such as hurricanes and tropical storms, on the broad geographic patterns of invasive species growth and spread have not been investigated. We used historical aerial imagery to determine the growth rate of invasive Phragmites australis patches in wetlands along the Atlantic and Gulf Coasts of the United States. These were relatively undisturbed wetlands where P. australis had room for unrestricted growth. Over the past several decades, invasive P. australis stands expanded in size by 6-35% per year. Based on tropical storm and hurricane activity over that same time period, we found that the frequency of hurricane-force winds explained 81% of the variation in P. australis growth over this broad geographic range. The expansion of P. australis stands was strongly and positively correlated with hurricane frequency. In light of the many climatic models that predict an increase in the frequency and intensity of hurricanes over the next century, these results suggest a strong link between climate change and species invasion and a challenging future ahead for the management of invasive species.

  6. Large zinc cation occupancy of octahedral sites in mechanically activated zinc ferrite powders

    SciTech Connect

    Oliver, S. A.; Harris, V. G.; Hamdeh, H. H.; Ho, J. C.

    2000-05-08

    The cation site occupancy of a mechanically activated nanocrystalline zinc ferrite powder was determined as (Zn{sub 0.55}{sup 2+}Fe{sub 0.18}{sup 3+}){sub tet}[Zr{sub 0.45}{sup 2+}Fe{sub 1.82}{sup 3+}]{sub oct}O{sub 4} through analysis of extended x-ray absorption fine structure measurements, showing a large redistribution of cations between sites compared to normal zinc ferrite samples. The overpopulation of cations in the octahedral sites was attributed to the ascendance in importance of the ionic radii over the crystal energy and bonding coordination in determining which interstitial sites are occupied in this structurally disordered powder. Slight changes are observed in the local atomic environment about the zinc cations, but not the iron cations, with respect to the spinel structure. The presence of Fe{sup 3+} on both sites is consistent with the measured room temperature magnetic properties. (c) 2000 American Institute of Physics.

  7. Magnetic Properties of Solar Active Regions that Govern Large Solar Flares and Eruptions

    NASA Astrophysics Data System (ADS)

    Toriumi, Shin; Schrijver, Carolus J.; Harra, Louise; Hudson, Hugh S.; Nagashima, Kaori

    2017-08-01

    Strong flares and CMEs are often produced from active regions (ARs). In order to better understand the magnetic properties and evolutions of such ARs, we conducted statistical investigations on the SDO/HMI and AIA data of all flare events with GOES levels >M5.0 within 45 deg from the disk center for 6 years from May 2010 (from the beginning to the declining phase of solar cycle 24). Out of the total of 51 flares from 29 ARs, more than 80% have delta-sunspots and about 15% violate Hale’s polarity rule. We obtained several key findings including (1) the flare duration is linearly proportional to the separation of the flare ribbons (i.e., scale of reconnecting magnetic fields) and (2) CME-eruptive events have smaller sunspot areas. Depending on the magnetic properties, flaring ARs can be categorized into several groups, such as spot-spot, in which a highly-sheared polarity inversion line is formed between two large sunspots, and spot-satellite, where a newly-emerging flux next to a mature sunspot triggers a compact flare event. These results point to the possibility that magnetic structures of the ARs determine the characteristics of flares and CMEs. In the presentation, we will also show new results from the systematic flux emergence simulations of delta-sunspot formation and discuss the evolution processes of flaring ARs.

  8. Characteristics of active regions associated to large solar energetic proton events

    NASA Astrophysics Data System (ADS)

    Bronarska, K.; Michalek, G.

    2017-01-01

    The relationship between properties of active regions (ARs) and solar energetic particles (SEP events, protons with energy ⩾10 MeV) is examined. For this purpose we study 84 SEP events recorded during the SOHO era (1996-2014). We compare properties of these SEP events with associated ARs, flares and CMEs. The ARs are characterized by McIntosh classification. Statistical analysis demonstrates that SEP events are more likely to be associated to the ARs having complex magnetic structures and the most energetic SEPs are ejected only from the associated ARs having a large and asymmetric penumbra. This tendency is used to estimate intensities of potential SEP events. For this purpose we express a probability of occurrence of an SEP event from a given AR which is correlated with fluxes of associated SEPs. We find that SEP events associated with ARs from eastern longitudes have to be more complex to produce SEP events at Earth. On the other hand, SEP particles originating from mid-longitudes (30 ° < longitude < 70 °) on the west side of solar disk are associated to the least complex ARs. These results could be useful for forecasting of space weather.

  9. The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Celotti, A.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Costamante, L.; Cotter, G.; Cutini, S.; D'Elia, V.; Dermer, C. D.; de Angelis, A.; de Palma, F.; De Rosa, A.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grandi, P.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hayashida, M.; Hays, E.; Healey, S. E.; Hill, A. B.; Horan, D.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lavalley, C.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Malaguti, G.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piranomonte, S.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ripken, J.; Ritz, S.; Rodriguez, A. Y.; Romani, R. W.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Shaw, M. S.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Stawarz, Ł.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Taylor, G. B.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Ubertini, P.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-05-01

    We present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazars based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. We compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.

  10. Hurricane Activity and the Large-Scale Pattern of Spread of an Invasive Plant Species

    PubMed Central

    Bhattarai, Ganesh P.; Cronin, James T.

    2014-01-01

    Disturbances are a primary facilitator of the growth and spread of invasive species. However, the effects of large-scale disturbances, such as hurricanes and tropical storms, on the broad geographic patterns of invasive species growth and spread have not been investigated. We used historical aerial imagery to determine the growth rate of invasive Phragmites australis patches in wetlands along the Atlantic and Gulf Coasts of the United States. These were relatively undisturbed wetlands where P. australis had room for unrestricted growth. Over the past several decades, invasive P. australis stands expanded in size by 6–35% per year. Based on tropical storm and hurricane activity over that same time period, we found that the frequency of hurricane-force winds explained 81% of the variation in P. australis growth over this broad geographic range. The expansion of P. australis stands was strongly and positively correlated with hurricane frequency. In light of the many climatic models that predict an increase in the frequency and intensity of hurricanes over the next century, these results suggest a strong link between climate change and species invasion and a challenging future ahead for the management of invasive species. PMID:24878928

  11. Fear conditioning suppresses large-conductance calcium-activated potassium channels in lateral amygdala neurons.

    PubMed

    Sun, P; Zhang, Q; Zhang, Y; Wang, F; Wang, L; Yamamoto, R; Sugai, T; Kato, N

    2015-01-01

    It was previously shown that depression-like behavior is accompanied with suppression of the large-conductance calcium activated potassium (BK) channel in cingulate cortex pyramidal cells. To test whether BK channels are also involved in fear conditioning, we studied neuronal properties of amygdala principal cells in fear conditioned mice. After behavior, we made brain slices containing the amygdala, the structure critically relevant to fear memory. The resting membrane potential in lateral amygdala (LA) neurons obtained from fear conditioned mice (FC group) was more depolarized than in neurons from naïve controls. The frequencies of spikes evoked by current injections were higher in neurons from FC mice, demonstrating that excitability of LA neurons was elevated by fear conditioning. The depolarization in neurons from FC mice was shown to depend on BK channels by using the BK channel blocker charybdotoxin. Suppression of BK channels in LA neurons from the FC group was further confirmed on the basis of the spike width, since BK channels affect the descending phase of spikes. Spikes were broader in the FC group than those in the naïve control in a manner dependent on BK channels. Consistently, quantitative real-time PCR revealed a decreased expression of BK channel mRNA. The present findings suggest that emotional disorder manifested in the forms of fear conditioning is accompanied with BK channel suppression in the amygdala, the brain structure critical to this emotional disorder.

  12. Promotoras as Data Collectors in a Large Study of Physical Activity in Parks

    PubMed Central

    Marsh, Terry; Derose, Kathryn Pitkin; Rios, Muriel; Cohen, Deborah

    2015-01-01

    There is a large literature on promotores’ involvement in health promotion and a smaller literature on their roles in data collection, most often among predominantly Latino populations. But the extent to which promotores can be successful as the primary data collectors across racially/ethnically and socioeconomically diverse neighborhoods is less well documented. In a study of physical activity in 50 urban neighborhood parks, we found that a team of Spanish/English bilingual promotoras (female promotores) successfully implemented a direct observation protocol in all participant neighborhoods and achieved high interrater reliability (.80-.98). Overall, they were also effective in administering surveys to park users and residents across the racially/ethnically diverse neighborhoods. The promotoras brought to the project important language skills and cultural sensitivity, surveying experience, and familiarity with human subjects and confidentiality issues. Their extensive field experience gained over the course of a long-term collaborative effort helped improve survey and observation protocols. The promotoras reported gaining professional skills, which can strengthen their contributions to other projects. The promotoras were accustomed to being a source of information, and collecting rather than providing information was challenging for some and had to be addressed in order to avoid contamination across study groups. PMID:25649234

  13. Rationally designed BCL6 inhibitors target activated B cell diffuse large B cell lymphoma

    PubMed Central

    Cardenas, Mariano G.; Yu, Wenbo; Beguelin, Wendy; Teater, Matthew R.; Geng, Huimin; Goldstein, Rebecca L.; Oswald, Erin; Hatzi, Katerina; Yang, Shao-Ning; Cohen, Joanna; Shaknovich, Rita; Vanommeslaeghe, Kenno; Cheng, Huimin; Liang, Dongdong; Cho, Hyo Je; Tam, Wayne; Du, Wei; Leonard, John P.; Elemento, Olivier; Cierpicki, Tomasz; Xue, Fengtian; MacKerell, Alexander D.; Melnick, Ari M.

    2016-01-01

    Diffuse large B cell lymphomas (DLBCLs) arise from proliferating B cells transiting different stages of the germinal center reaction. In activated B cell DLBCLs (ABC-DLBCLs), a class of DLBCLs that respond poorly to current therapies, chromosomal translocations and amplification lead to constitutive expression of the B cell lymphoma 6 (BCL6) oncogene. The role of BCL6 in maintaining these lymphomas has not been investigated. Here, we designed small-molecule inhibitors that display higher affinity for BCL6 than its endogenous corepressor ligands to evaluate their therapeutic efficacy for targeting ABC-DLBCL. We used an in silico drug design functional-group mapping approach called SILCS to create a specific BCL6 inhibitor called FX1 that has 10-fold greater potency than endogenous corepressors and binds an essential region of the BCL6 lateral groove. FX1 disrupted formation of the BCL6 repression complex, reactivated BCL6 target genes, and mimicked the phenotype of mice engineered to express BCL6 with corepressor binding site mutations. Low doses of FX1 induced regression of established tumors in mice bearing DLBCL xenografts. Furthermore, FX1 suppressed ABC-DLBCL cells in vitro and in vivo, as well as primary human ABC-DLBCL specimens ex vivo. These findings indicate that ABC-DLBCL is a BCL6-dependent disease that can be targeted by rationally designed inhibitors that exceed the binding affinity of natural BCL6 ligands. PMID:27482887

  14. Improved confinement region without large magnetohydrodynamic activity in TPE-RX reversed-field pinch plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Hirano, Yoichi; Sakakita, Hajime; Koguchi, Haruhisa

    2014-11-01

    We found that spontaneous improved confinement was brought about depending on the operating region in the Toroidal Pinch Experiment-Reversed eXperiment (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. Gradual decay of the toroidal magnetic field at plasma surface Btw reversal makes it possible to realize a prolonged discharge, and the poloidal beta value and energy confinement time increase in the latter half of the discharge, where reversal and pinch parameters become shallow and low, respectively. In the latter half of the discharge, the plasma current and volume-averaged toroidal magnetic field increase again, the electron density slowly decays, the electron temperature and soft X-ray radiation intensity increase, and the magnetic fluctuations are markedly reduced. In this period of improved confinement, the value of (-Btw)/Bpw, where Bpw is the poloidal magnetic field at the plasma surface, stays almost constant, which indicates that the dynamo action occurs without large magnetohydrodynamic activities.

  15. Improved confinement region without large magnetohydrodynamic activity in TPE-RX reversed-field pinch plasma

    SciTech Connect

    Yambe, Kiyoyuki; Hirano, Yoichi; Sakakita, Hajime; Koguchi, Haruhisa

    2014-11-15

    We found that spontaneous improved confinement was brought about depending on the operating region in the Toroidal Pinch Experiment-Reversed eXperiment (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. Gradual decay of the toroidal magnetic field at plasma surface B{sub tw} reversal makes it possible to realize a prolonged discharge, and the poloidal beta value and energy confinement time increase in the latter half of the discharge, where reversal and pinch parameters become shallow and low, respectively. In the latter half of the discharge, the plasma current and volume-averaged toroidal magnetic field 〈B{sub t}〉 increase again, the electron density slowly decays, the electron temperature and soft X-ray radiation intensity increase, and the magnetic fluctuations are markedly reduced. In this period of improved confinement, the value of (〈B{sub t}〉-B{sub tw})/B{sub pw}, where B{sub pw} is the poloidal magnetic field at the plasma surface, stays almost constant, which indicates that the dynamo action occurs without large magnetohydrodynamic activities.

  16. Dynamics of large-scale brain activity in normal arousal states and epileptic seizures

    NASA Astrophysics Data System (ADS)

    Robinson, P. A.; Rennie, C. J.; Rowe, D. L.

    2002-04-01

    Links between electroencephalograms (EEGs) and underlying aspects of neurophysiology and anatomy are poorly understood. Here a nonlinear continuum model of large-scale brain electrical activity is used to analyze arousal states and their stability and nonlinear dynamics for physiologically realistic parameters. A simple ordered arousal sequence in a reduced parameter space is inferred and found to be consistent with experimentally determined parameters of waking states. Instabilities arise at spectral peaks of the major clinically observed EEG rhythms-mainly slow wave, delta, theta, alpha, and sleep spindle-with each instability zone lying near its most common experimental precursor arousal states in the reduced space. Theta, alpha, and spindle instabilities evolve toward low-dimensional nonlinear limit cycles that correspond closely to EEGs of petit mal seizures for theta instability, and grand mal seizures for the other types. Nonlinear stimulus-induced entrainment and seizures are also seen, EEG spectra and potentials evoked by stimuli are reproduced, and numerous other points of experimental agreement are found. Inverse modeling enables physiological parameters underlying observed EEGs to be determined by a new, noninvasive route. This model thus provides a single, powerful framework for quantitative understanding of a wide variety of brain phenomena.

  17. Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure.

    PubMed

    Tatariw, Corianne; Chapman, Elise L; Sponseller, Ryan A; Mortazavi, Behzad; Edmonds, Jennifer W

    2013-10-01

    Ecological theory argues that the controls over ecosystem processes are structured hierarchically, with broader-scale drivers acting as constraints over the interactions and dynamics at nested levels of organization. In river ecosystems, these interactions may arise from broadscale variation in channel form that directly shapes benthic habitat structure and indirectly constrains resource supply and biological activity within individual reaches. To evaluate these interactions, we identified sediment characteristics, water chemistry, and denitrifier community structure as factors influencing benthic denitrification rates in a sixth-order river that flows through two physiographic provinces and the transitional zone between them, each with distinct geomorphological properties. We found that denitrification rates tracked spatial changes in sediment characteristics and varied seasonally with expected trends in stream primary production. Highest rates were observed during the spring and summer seasons in the physiographic province dominated by fine-grained sediments, illustrating how large-scale changes in river structure can constrain the location of denitrification hotspots. In addition, nirS and nirK community structure each responded differently to variation in channel form, possibly due to changes in dissolved oxygen and organic matter supply. This shift in denitrifier community structure coincident with higher rates of N removal via denitrification suggests that microbial community structure may influence biogeochemical processes.

  18. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

    NASA Astrophysics Data System (ADS)

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R.; Yakobson, Boris I.; McCarty, Kevin F.; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S.

    2016-05-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional ‘surface-limited’ growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to ˜100 meV at a displacement field of 0.9 V nm-1.

  19. Baroreflexes of the rat. V. Tetanus-induced potentiation of ADN A-fiber responses at the NTS.

    PubMed

    Tang, Xiaorui; Dworkin, Barry R

    2007-12-01

    In a long-term neuromuscular blocked (NMB) rat preparation, tetanic stimulation of the aortic depressor nerve (ADN) enhanced the A-fiber evoked responses (ERs) in the cardiovascular region, the nucleus of the solitary tract (dmNTS). The potentiation persisted for at least several hours and may be a mechanism for adaptive adjustment of the gain of the baroreflex, with functional implications for blood pressure regulation. Using a capacitance electrode, we selectively stimulated A-fibers and acquired a stable 10-h "A-fiber only" ER baseline at the dmNTS. Following baseline, an A+C-fiber activating tetanus was applied to the ADN. The tetanus consisted of 1,000 "high current" pulses (10 trains; 300 mus, 100 Hz, 1 s), with intertrain interval of 9 s. A 10-h A-fiber only posttetanic test phase repeated the stimulus pattern of the baseline. Fourteen tetanus experiments were done in 12 rats. Compared with the baseline before tetanus, the A-fiber ER magnitudes of posttetanus hours were larger [F(13, 247) = 3.407, P < .001]; additionally, the 10-h posttetanus magnitude slopes were more positive than during 10 h before tetanus (df = 13; t = -3.47; P < 0.005); thus, an ADN A+C fiber-activating tetanus produced increases in the magnitude of the A-fiber ERs in the dmNTS that persisted for several hours. In an additional rat, application of an NMDA receptor antagonist, prior to the tetanus, blocked the potentiation effect. The stimulus protocols, magnitude and duration of the effect, and pharmacology resemble associative long-term potentiation (LTP).

  20. Paraoxonase-1 activity is positively related to phospholipid transfer protein activity in type 2 diabetes mellitus: Role of large HDL particles.

    PubMed

    Dullaart, Robin P F; Gruppen, Eke G; Dallinga-Thie, Geesje M

    2016-04-01

    High density lipoprotein (HDL)-associated paraoxonase-1 (PON-1) exerts anti-oxidative properties, whereas phospholipid transfer protein (PLTP) is able to convert mature HDL into larger and smaller HDL particles. Here we tested associations of PON-1 with PLTP in type 2 diabetes mellitus (T2DM), a condition characterized by lower PON-1 activity and higher PLTP activity. Serum PON-1 (arylesterase activity), plasma PLTP activity (liposome-vesicle HDL system), and (apo)lipoproteins were measured in 81 T2DM subjects (mean age 59±9years; 31 women; no insulin treatment). In 48 participants, HDL subfractions were measured by nuclear magnetic resonance spectroscopy. In univariate correlation analysis, PON-1 activity was positively related to PLTP activity (r=0.348, p=0.001). PLTP activity was positively related to blood pressure, body mass index and triglycerides, whereas PON-1 activity was positively to HDL cholesterol and apoA-I (p<0.05 to <0.01 for each). Both PLTP activity and PON-I activity were positively related to large HDL particles (r=0.379, p=0.008 and r=0.411, p=0.004, respectively). In multivariable linear regression analysis, PON-1 activity was associated with PLTP activity independent of clinical covariates and HDL cholesterol or apoA-I (β=0.340, p=0.001 and β=0.320, p=0.003, respectively). The association of PON-1 activity with PLTP activity was lost in analysis which included large HDL particles (large HDL: β=0.411, p=0.004). PON-1 activity is positively related to PLTP activity in T2DM, raising the possibility that PLTP could act to maintain PON-1. This association may in part be attributable to a common relationship of PON-1 and PLTP with large HDL particles. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  1. Cohort Profile of the Goals Study: A Large-Scale Research of Physical Activity in Dutch Students

    ERIC Educational Resources Information Center

    de Groot, Renate H. M.; van Dijk, Martin L.; Kirschner, Paul A.

    2015-01-01

    The GOALS study (Grootschalig Onderzoek naar Activiteiten van Limburgse Scholieren [Large-scale Research of Activities in Dutch Students]) was set up to investigate possible associations between different forms of physical activity and inactivity with cognitive performance, academic achievement and mental well-being. It was conducted at a…

  2. Cohort Profile of the Goals Study: A Large-Scale Research of Physical Activity in Dutch Students

    ERIC Educational Resources Information Center

    de Groot, Renate H. M.; van Dijk, Martin L.; Kirschner, Paul A.

    2015-01-01

    The GOALS study (Grootschalig Onderzoek naar Activiteiten van Limburgse Scholieren [Large-scale Research of Activities in Dutch Students]) was set up to investigate possible associations between different forms of physical activity and inactivity with cognitive performance, academic achievement and mental well-being. It was conducted at a…

  3. Large-Scale Investigation of the Role of Trait Activation Theory for Understanding Assessment Center Convergent and Discriminant Validity

    ERIC Educational Resources Information Center

    Lievens, Filip; Chasteen, Christopher S.; Day, Eric Anthony; Christiansen, Neil D.

    2006-01-01

    This study used trait activation theory as a theoretical framework to conduct a large-scale test of the interactionist explanation of the convergent and discriminant validity findings obtained in assessment centers. Trait activation theory specifies the conditions in which cross-situationally consistent and inconsistent candidate performances are…

  4. A fiber-bridging model with stress gradient effects

    NASA Astrophysics Data System (ADS)

    Yi, Sun; Tao, Li

    2000-05-01

    A fiber-bridging model with stress gradient effects is proposed for unidirectional fiber-reinforced composites. The stress gradient terms are introduced by solving a micromechanical model under a non-uniform stress loading. It is shown that the stress gradient effect is significant on both the fiber-bridging stress distribution and the value of the critical load of fiber failure.

  5. mTOR activity in AIDS-related diffuse large B-cell lymphoma

    PubMed Central

    Diaz-Perez, Julio A.; Preziosi, Michael; King, Charles C.; Jones, George A.; Jain, Sonia; Sun, Xiaoying; Reid, Erin G.; VandenBerg, Scott; Wang, Huan-You

    2017-01-01

    Background Patients infected with HIV have a significantly increased risk of developing non–Hodgkin lymphomas despite the widespread use of HAART. To investigate mTOR pathway activity in acquired immunodeficiency syndrome (AIDS) related diffuse large B-cell lymphoma AR-DLBCL, we used immunohistochemistry to examine the presence of the phosphorylated 70 ribosomal S6 protein-kinase (p70S6K), an extensively studied effector of mTOR Complex 1 (mTORC1) and the phosphorylated phosphatase and tensin homolog (pPTEN), a negative regulator of mTORC1 pathway. Materials and methods We evaluated tissue samples from 126 patients with AR-DLBCL. Among them, 98 samples were from tissue microarrays (TMAs) supplied by the Aids and Cancer Specimen Resource (ACSR), the remaining 28 samples were from cases diagnosed and treated at the University of California, San Diego (UCSD). The presence of p70S6K was evaluated with two antibodies directed against the combined epitopes Ser235/236 and Ser240/244, respectively; and additional monoclonal anti-bodies were used to identify pPTEN and phosphorylated proline-rich Akt substrate of 40kDa (pPRAS40). The degree of intensity and percentage of cells positive for p70S6K and pPTEN were assessed in all the samples. In addition, a subgroup of 28 patients from UCSD was studied to assess the presence of pPRAS40, an insulin-regulated activator of the mTORC1. The expression of each of these markers was correlated with clinical and histopathologic features. Results The majority of the patients evaluated were males (88%); only two cases (1.6%) were older than 65 years of age. We found high levels of both p70S6K-paired epitopes studied, 48% positivity against Ser235/236 (44% in ACSR and 64% in UCSD group), and 86% positivity against Ser240/244 (82% in ACSR and 100% in UCSD group). We observed more positive cells and stronger intensity with epitope Ser240/244 in comparison to Ser235/236 (p<0.0001). The degree of intensity and percentage of cells positive

  6. Upregulation of the large conductance voltage- and Ca2+-activated K+ channels by Janus kinase 2.

    PubMed

    Hosseinzadeh, Zohreh; Almilaji, Ahmad; Honisch, Sabina; Pakladok, Tatsiana; Liu, GuoXing; Bhavsar, Shefalee K; Ruth, Peter; Shumilina, Ekaterina; Lang, Florian

    2014-06-01

    The iberiotoxin-sensitive large conductance voltage- and Ca(2+)-activated potassium (BK) channels (maxi-K(+)-channels) hyperpolarize the cell membrane thus supporting Ca(2+) entry through Ca(2+)-release activated Ca(2+) channels. Janus kinase-2 (JAK2) has been identified as novel regulator of ion transport. To explore whether JAK2 participates in the regulation of BK channels, cRNA encoding Ca(2+)-insensitive BK channels (BK(M513I+Δ899-903)) was injected into Xenopus oocytes with or without cRNA encoding wild-type JAK2, gain-of-function (V617F)JAK2, or inactive (K882E)JAK2. K(+) conductance was determined by dual electrode voltage clamp and BK-channel protein abundance by confocal microscopy. In A204 alveolar rhabdomyosarcoma cells, iberiotoxin-sensitive K(+) current was determined utilizing whole cell patch clamp. A204 cells were further transfected with JAK2 and BK-channel transcript, and protein abundance was quantified by RT-PCR and Western blotting, respectively. As a result, the K(+) current in BK(M513I+Δ899-903)-expressing oocytes was significantly increased following coexpression of JAK2 or (V617F)JAK2 but not (K882E)JAK2. Coexpression of the BK channel with (V617F)JAK2 but not (K882E)JAK2 enhanced BK-channel protein abundance in the oocyte cell membrane. Exposure of BK-channel and (V617F)JAK2-expressing oocytes to the JAK2 inhibitor AG490 (40 μM) significantly decreased K(+) current. Inhibition of channel insertion by brefeldin A (5 μM) decreased the K(+) current to a similar extent in oocytes expressing the BK channel alone and in oocytes expressing the BK channel and (V617F)JAK2. The iberiotoxin (50 nM)-sensitive K(+) current in rhabdomyosarcoma cells was significantly decreased by AG490 pretreatment (40 μM, 12 h). Moreover, overexpression of JAK2 in A204 cells significantly enhanced BK channel mRNA and protein abundance. In conclusion, JAK2 upregulates BK channels by increasing channel protein abundance in the cell membrane.

  7. Large historical earthquakes and tsunamis in a very active tectonic rift: the Gulf of Corinth, Greece

    NASA Astrophysics Data System (ADS)

    Triantafyllou, Ioanna; Papadopoulos, Gerassimos

    2014-05-01

    The Gulf of Corinth is an active tectonic rift controlled by E-W trending normal faults with an uplifted footwall in the south and a subsiding hangingwall with antithetic faulting in the north. Regional geodetic extension rates up to about 1.5 cm/yr have been measured, which is one of the highest for tectonic rifts in the entire Earth, while seismic slip rates up to about 1 cm/yr were estimated. Large earthquakes with magnitudes, M, up to about 7 were historically documented and instrumentally recorded. In this paper we have compiled historical documentation of earthquake and tsunami events occurring in the Corinth Gulf from the antiquity up to the present. The completeness of the events reported improves with time particularly after the 15th century. The majority of tsunamis were caused by earthquake activity although the aseismic landsliding is a relatively frequent agent for tsunami generation in Corinth Gulf. We focus to better understand the process of tsunami generation from earthquakes. To this aim we have considered the elliptical rupture zones of all the strong (M≥ 6.0) historical and instrumental earthquakes known in the Corinth Gulf. We have taken into account rupture zones determined by previous authors. However, magnitudes, M, of historical earthquakes were recalculated from a set of empirical relationships between M and seismic intensity established for earthquakes occurring in Greece during the instrumental era of seismicity. For this application the macroseismic field of each one of the earthquakes was identified and seismic intensities were assigned. Another set of empirical relationships M/L and M/W for instrumentally recorded earthquakes in the Mediterranean region was applied to calculate rupture zone dimensions; where L=rupture zone length, W=rupture zone width. The rupture zones positions were decided on the basis of the localities of the highest seismic intensities and co-seismic ground failures, if any, while the orientation of the maximum

  8. The first catalog of active galactic nuclei detected by the FERMI large area telescope

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-04-29

    Here, we present the first catalog of active galactic nuclei (AGNs) detected by the Large Area Telescope (LAT), corresponding to 11 months of data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are detected with a test statistic greater than 25 and associated statistically with AGNs. Some LAT sources are associated with multiple AGNs, and consequently, the catalog includes 709 AGNs, comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs of other types, and 72 AGNs of unknown type. We also classify the blazarsmore » based on their spectral energy distributions as archival radio, optical, and X-ray data permit. In addition to the formal 1LAC sample, we provide AGN associations for 51 low-latitude LAT sources and AGN "affiliations" (unquantified counterpart candidates) for 104 high-latitude LAT sources without AGN associations. The overlap of the 1LAC with existing γ-ray AGN catalogs (LBAS, EGRET, AGILE, Swift, INTEGRAL, TeVCat) is briefly discussed. Various properties—such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. Lastly, we compare the 1LAC results with predictions regarding the γ-ray AGN populations, and we comment on the power of the sample to address the question of the blazar sequence.« less

  9. Fermi Large Area Telescope Observations Of Misaligned Active Galactic Nuclei

    SciTech Connect

    Abdo, A. A.

    2010-08-13

    Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a γ-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sources associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The γ-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the γ-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the γ-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the γ-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.

  10. The Second Catalog Of Active Galactic Nuclei Detected By The Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.

    2011-12-02

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently we define a clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lacs), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars ofmore » unknown type (i.e., with broad-band blazar characteristics but with no optical spectral measurement yet), eight misaligned AGNs, four narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types and two starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency < 1014 Hz, about half of the BL Lacs have a synchrotron-peak frequency > 1015 Hz. The 2LAC represents a significant improvement relative to the First LAT AGN Catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broad-band data. Various properties, such as γ-ray fluxes and photon power law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities—and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.« less

  11. The Activity of Differentiation Factors Induces Apoptosis in Polyomavirus Large T-Expressing Myoblasts

    PubMed Central

    Fimia, Gian Maria; Gottifredi, Vanesa; Bellei, Barbara; Ricciardi, Maria Rosaria; Tafuri, Agostino; Amati, Paolo; Maione, Rossella

    1998-01-01

    It is commonly accepted that pathways that regulate proliferation/differentiation processes, if altered in their normal interplay, can lead to the induction of programmed cell death. In a previous work we reported that Polyoma virus Large Tumor antigen (PyLT) interferes with in vitro terminal differentiation of skeletal myoblasts by binding and inactivating the retinoblastoma antioncogene product. This inhibition occurs after the activation of some early steps of the myogenic program. In the present work we report that myoblasts expressing wild-type PyLT, when subjected to differentiation stimuli, undergo cell death and that this cell death can be defined as apoptosis. Apoptosis in PyLT-expressing myoblasts starts after growth factors removal, is promoted by cell confluence, and is temporally correlated with the expression of early markers of myogenic differentiation. The block of the initial events of myogenesis by transforming growth factor β or basic fibroblast growth factor prevents PyLT-induced apoptosis, while the acceleration of this process by the overexpression of the muscle-regulatory factor MyoD further increases cell death in this system. MyoD can induce PyLT-expressing myoblasts to accumulate RB, p21, and muscle- specific genes but is unable to induce G00 arrest. Several markers of different phases of the cell cycle, such as cyclin A, cdk-2, and cdc-2, fail to be down-regulated, indicating the occurrence of cell cycle progression. It has been frequently suggested that apoptosis can result from an unbalanced cell cycle progression in the presence of a contrasting signal, such as growth factor deprivation. Our data involve differentiation pathways, as a further contrasting signal, in the generation of this conflict during myoblast cell apoptosis. PMID:9614186

  12. A tale of two carenes: intrinsic optical activity and large-amplitude nuclear displacement.

    PubMed

    Lahiri, Priyanka; Wiberg, Kenneth B; Vaccaro, Patrick H

    2012-09-27

    The specific rotation for two isomeric members of the terpene family, (S)-(+)-2-carene and (S)-(+)-3-carene, has been investigated under complementary solvated and isolated conditions, where the latter vapor-phase work has been performed at excitation wavelengths of 355 and 633 nm by means of ultrasensitive cavity ring-down polarimetry (CRDP). Linear-response computations of dispersive optical activity built upon analogous density-functional (B3LYP/aug-cc-pVTZ) and coupled-cluster (CCSD/aug-cc-pVDZ) levels of theory have been enlisted to unravel the structural and electronic origins of observed behavior. The six-membered portion of the bicyclic skeleton in the nominally rigid 3-carene system is predicted to be near-planar in nature, with calculated and measured rotatory powers for the isolated (gas-phase) species shown to be in excellent agreement. In contrast, the inherent flexibility of 2-carene gives rise to two quasidegenerate conformations that are interconnected by a large-amplitude ring-puckering motion and exhibit antagonistic chiroptical properties. Various approaches to simulate the intrinsic response evoked from a thermally equilibrated ensemble of gaseous (S)-(+)-2-carene molecules have been considered, including implicit averaging over independent conformers and explicit (albeit restricted) averaging over nuclear degrees of freedom. A polarizable continuum model for implicit solvation was found to describe solvent-dependent trends reasonably well in the case of (S)-(+)-2-carene, but failed to reproduce the specific-rotation patterns emerging from polarimetric studies of (S)-(+)-3-carene.

  13. Intracellular Na(+) modulates large conductance Ca(2+)-activated K (+) currents in human umbilical vein endothelial cells.

    PubMed

    Liang, Guo Hua; Kim, Moon Young; Park, Seonghee; Kim, Ji Aee; Choi, Shinkyu; Suh, Suk Hyo

    2008-10-01

    We studied the effects of Na(+) influx on large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels in cultured human umbilical vein endothelial cells (HUVECs) by means of patch clamp and SBFI microfluorescence measurements. In current-clamped HUVECs, extracellular Na(+) replacement by NMDG(+) or mannitol hyperpolarized cells. In voltage-clamped HUVECs, changing membrane potential from 0 mV to negative potentials increased intracellular Na(+) concentration ([Na(+)](i)) and vice versa. In addition, extracellular Na(+) depletion decreased [Na(+)](i). In voltage-clamped cells, BK(Ca) currents were markedly increased by extracellular Na(+) depletion. In inside-out patches, increasing [Na(+)](i) from 0 to 20 or 40 mM reduced single channel conductance but not open probability (NPo) of BK(Ca) channels and decreasing intracellular K(+) concentration ([K(+)](i)) gradually from 140 to 70 mM reduced both single channel conductance and NPo. Furthermore, increasing [Na(+)](i) gradually from 0 to 70 mM, by replacing K(+), markedly reduced single channel conductance and NPo. The Na(+)-Ca(2+) exchange blocker Ni(2+) or KB-R7943 decreased [Na(+)](i) and increased BK(Ca) currents simultaneously, and the Na(+) ionophore monensin completely inhibited BK(Ca) currents. BK(Ca) currents were significantly augmented by increasing extracellular K(+) concentration ([K(+)](o)) from 6 to 12 mM and significantly reduced by decreasing [K(+)](o) from 12 or 6 to 0 mM or applying the Na(+)-K(+) pump inhibitor ouabain. These results suggest that intracellular Na(+) inhibit single channel conductance of BK(Ca) channels and that intracellular K(+) increases single channel conductance and NPo.

  14. Allosteric Gating of a Large Conductance Ca-activated K+ Channel

    PubMed Central

    Cox, D.H.; Cui, J.; Aldrich, R.W.

    1997-01-01

    Large-conductance Ca-activated potassium channels (BK channels) are uniquely sensitive to both membrane potential and intracellular Ca2+. Recent work has demonstrated that in the gating of these channels there are voltage-sensitive steps that are separate from Ca2+ binding steps. Based on this result and the macroscopic steady state and kinetic properties of the cloned BK channel mslo, we have recently proposed a general kinetic scheme to describe the interaction between voltage and Ca2+ in the gating of the mslo channel (Cui, J., D.H. Cox, and R.W. Aldrich. 1997. J. Gen. Physiol. In press.). This scheme supposes that the channel exists in two main conformations, closed and open. The conformational change between closed and open is voltage dependent. Ca2+ binds to both the closed and open conformations, but on average binds more tightly to the open conformation and thereby promotes channel opening. Here we describe the basic properties of models of this form and test their ability to mimic mslo macroscopic steady state and kinetic behavior. The simplest form of this scheme corresponds to a voltage-dependent version of the Monod-Wyman-Changeux (MWC) model of allosteric proteins. The success of voltage-dependent MWC models in describing many aspects of mslo gating suggests that these channels may share a common molecular mechanism with other allosteric proteins whose behaviors have been modeled using the MWC formalism. We also demonstrate how this scheme can arise as a simplification of a more complex scheme that is based on the premise that the channel is a homotetramer with a single Ca2+ binding site and a single voltage sensor in each subunit. Aspects of the mslo data not well fitted by the simplified scheme will likely be better accounted for by this more general scheme. The kinetic schemes discussed in this paper may be useful in interpreting the effects of BK channel modifications or mutations. PMID:9276753

  15. Relationships Between Neighborhoods, Physical Activity, and Obesity: A Multilevel Analysis of a Large Canadian City

    PubMed Central

    Prince, Stephanie A.; Kristjansson, Elizabeth A.; Russell, Katherine; Billette, Jean-Michel; Sawada, Michael C.; Ali, Amira; Tremblay, Mark S.; Prud'homme, Denis

    2012-01-01

    In Canada, there is limited research examining the associations between objectively measured neighborhood environments and physical activity (PA) and obesity. The purpose of this study was to determine the relationships between variables from built and social environments and PA and overweight/obesity across 86 Ottawa, Canada neighborhoods. Individual-level data including self-reported leisure-time PA (LTPA), height, and weight were examined in a sample of 4,727 adults from four combined cycles (years 2001/03/05/07) of the Canadian Community Health Survey (CCHS). Data on neighborhood characteristics were obtained from the Ottawa Neighbourhood Study (ONS); a large study of neighborhoods and health in Ottawa, Canada. Binomial multivariate multilevel models were used to examine the relationships between environmental and individual variables with LTPA and overweight/obesity using survey weights in men and women separately. Within the sample, ~75% of the adults were inactive (<3.0 kcal/kg/day) while half were overweight/obese. Results of the multilevel models suggested that for females greater park area was associated with increased odds of LTPA and overweight/obesity. Greater neighborhood density of convenience stores and fast food outlets were associated with increased odds of females being overweight/obese. Higher crime rates were associated with greater odds of LTPA in males, and lower odds of male and female overweight/obesity. Season was significantly associated with PA in men and women; the odds of LTPA in winter months were half that of summer months. Findings revealed that park area, crime rates, and neighborhood food outlets may have different roles with LTPA and overweight/obesity in men and women and future prospective studies are needed. PMID:22262164

  16. The Active and Periactive Zone Organization and the Functional Properties of Small and Large Synapses

    PubMed Central

    Cano, Raquel; Tabares, Lucia

    2016-01-01

    The arrival of an action potential (AP) at a synaptic terminal elicits highly synchronized quanta release. Repetitive APs produce successive synaptic vesicle (SV) fusions that require management of spent SV components in the presynaptic membrane with minimum disturbance of the secretory apparatus. To this end, the synaptic machinery is structured accordingly to the strength and the range of frequencies at which each particular synapse operates. This results in variations in the number and dimension of Active Zones (AZs), amount and distribution of SVs, and probably, in the primary endocytic mechanisms they use. Understanding better how these structural differences determine the functional response in each case has been a matter of long-term interest. Here we review the structural and functional properties of three distinct types of synapses: the neuromuscular junction (NMJ; a giant, highly reliable synapse that must exocytose a large number of quanta with each stimulus to guarantee excitation of the postsynaptic cell), the hippocampal excitatory small synapse (which most often has a single release site and a relatively small pool of vesicles), and the cerebellar mossy fiber-granule cell synapse (which possesses hundreds of release sites and is able to translocate, dock and prime vesicles at high speed). We will focus on how the release apparatus is organized in each case, the relative amount of vesicular membrane that needs to be accommodated within the periAZ upon stimulation, the different mechanisms for retrieving the excess of membrane and finally, how these factors may influence the functioning of the release sites. PMID:27252645

  17. THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Bouvier, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Bastieri, D. E-mail: sarac@slac.stanford.edu E-mail: charles.dermer@nrl.navy.mil; and others

    2011-12-20

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 {gamma}-ray sources located at high Galactic latitudes (|b| > 10 Degree-Sign ) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a Clean Sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency <10{sup 14} Hz, about half of the BL Lac objects have a synchrotron-peak frequency >10{sup 15} Hz. The 2LAC represents a significant improvement relative to the first LAT AGN catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broadband data. Various properties, such as {gamma}-ray fluxes and photon power-law spectral indices, redshifts, {gamma}-ray luminosities, variability, and archival radio luminosities and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.

  18. M2 Muscarinic Receptors Induce Airway Smooth Muscle Activation via a Dual, Gβγ-mediated Inhibition of Large Conductance Ca2+-activated K+ Channel Activity*

    PubMed Central

    Zhou, Xiao-Bo; Wulfsen, Iris; Lutz, Susanne; Utku, Emine; Sausbier, Ulrike; Ruth, Peter; Wieland, Thomas; Korth, Michael

    2008-01-01

    Airway smooth muscle is richly endowed with muscarinic receptors of the M2 and M3 subtype. Stimulation of these receptors inhibits large conductance calcium-activated K+ (BK) channels, a negative feed back regulator, in a pertussis toxinsensitive manner and thus facilitates contraction. The underlying mechanism, however, is unknown. We therefore studied the activity of bovine trachea BK channels in HEK293 cells expressing the M2 or M3 receptor (M2RorM3R). In M2R- but not M3R-expressing cells, maximal effective concentrations of carbamoylcholine (CCh) inhibited whole cell BK currents by 53%. This M2R-induced inhibition was abolished by pertussis toxin treatment or overexpression of the Gβγ scavenger transducin-α. In inside-out patches, direct application of 300 nm purified Gβγ decreased channel open probability by 55%. The physical interaction of Gβγ with BK channels was confirmed by co-immunoprecipitation. Interestingly, inhibition of phospholipase C as well as protein kinase C activities also reversed the CCh effect but to a smaller (∼20%) extent. Mouse tracheal cells responded similarly to CCh, purified Gβγ and phospholipase C/protein kinase C inhibition as M2R-expressing HEK293 cells. Our results demonstrate that airway M2Rs inhibit BK channels by a dual, Gβγ-mediated mechanism, a direct membrane-delimited interaction, and the activation of the phospholipase C/protein kinase C pathway. PMID:18524769

  19. Estrogenic Activity and Estrogens of Surface Waters in Proximity to a Large Dairy

    USDA-ARS?s Scientific Manuscript database

    Large concentrated animal farms have been the subject of intense public scrutiny, in part due to concern about environmental release of endocrine disruptors. To assess the potential impact of a large dairy herd (greater than 2000 milking head) using best management practices, area surface waters and...

  20. Relationships between persistent large-scale flow anomalies and variation in synoptic-scale eddy activity and cyclogenesis

    NASA Technical Reports Server (NTRS)

    Dole, Randall M.; Neilley, Peter P.

    1988-01-01

    Observational analyses to study the relationships between large-scale flow anomalies and variations in synoptic-scale eddy activity and cyclogenesis are presented. The way in which changes in the large-scale flow influence the behavior of synoptic-scale eddies and the way in which changes in eddies may feedback to influence the large-scale flow anomalies are examined. Situations characterized by differing large-scale flows are compared, showing well-defined diferences in synoptic-scale eddy activity. The net forcings of anomalous mean flows by eddies as deduced from tendency methods and E-vector analyses suggest that synoptic-scale eddies may play an important role in maintaining certain anomalous flow patterns such as blocking.

  1. Continuous monitoring of a large active earth flow using an integrated GPS - automatic total station approach

    NASA Astrophysics Data System (ADS)

    Corsini, A.

    2009-04-01

    Landslide monitoring has evolved as a crucial tool in civil protection to mitigate and prevent disasters. The research presents an approach to continuous monitoring of a large-scale active earth flow using a system that integrates surface measurements obtained by a GPS and an automatic total station. With the data obtained from the system the landslide can be monitored in near-real-time and surface displacements can be directly utilized to provide early warning of slope movements and to study the behavior of the landslide, e.g. to predict timing and mechanisms of future failure. The Valoria landslide located in the northern Apennines of Italy was reactivated in 2001, 2005 and 2007 damaging roads and endangering houses. A monitoring system was installed in 2007-2008 in the frame of a civil protection plan aimed at risk mitigation. The system consists of an automatic total station measuring about 40 prisms located in the landslide to a maximum distance of 1.800 km; one double-frequency GPS receiver connects in streaming by wireless communication with 4 single-frequency GPS in side the flow. Until December 2007 the monitoring network was operated with periodic static surveying followed by the data post-processing. From September 2007 until March 2008 the landslide deformation was evaluated by periodic surveys with the total station and the GPS system. This first measure showed that the displacements were influenced by the rainfall events and by the snow melting. The total displacements measured vary from centimeter scale in the crown zone, where retrogressive movements were in progress, to over 50 m in the flow track zone. Starting in March 2008 data acquisition by the total station system and GPS were automated in order to allow continuous and near-real-time data processing. The displacement data collected in one and a half year of continuous operation show different acceleration and deceleration phases as a result of the pore water pressure distribution inside the

  2. Island of the Sharks Activity Guide To Accompany the Large-Format Film.

    ERIC Educational Resources Information Center

    Gowell, Elizabeth Tayntor

    This document targets upper elementary and middle school students and provides activities to understand what the ocean floor looks like, the interactions of ocean communities, and the true nature of sharks. The activities are developed at three levels: beginner, intermediate, and advanced. The twelve activities include: (1) "Ocean…

  3. Study of new FNAL-NICADD extruded scintillator as active media of large EMCal of ALICE at LHC

    SciTech Connect

    Oleg A. Grachov et al.

    2004-05-04

    The current conceptual design of proposed Large EMCal of ALICE at LHC is based largely on the scintillating mega-tile/fiber technology implemented in CDF Endplug upgrade project and in both barrel and endcap electromagnetic calorimeters of the STAR. The cost of scintillating material leads us to the choice of extruded polystyrene based scintillator, which is available in new FNAL-NICADD facility. Result of optical measurements, such as light yield and light yield variation, show that it is possible to use this material as active media of Large EMCal of ALICE at LHC.

  4. Study of New Fnal-Nicadd Extruded Scintillator as Active Media of Large Emcal of ALICE at Lhc

    NASA Astrophysics Data System (ADS)

    Grachov, O. A.; Cormier, T. M.; Pla-Dalmau, A.; Bross, A.; Rykalin, V.

    2005-02-01

    The current conceptual design of proposed Large EMCal of ALICE at LHC is based largely on the scintillating mega-tile/fiber technology implemented in CDF Endplug upgrade project and in both barrel and endcap electromagnetic calorimeters of the STAR. The cost of scintillating material leads us to choose extruded polystyrene based scintillator, which is available in new FNAL-NICADD facility. Results of optical measurements, such as light yield and light yield variation, show that it is possible to use this material as active media of Large EMCal of ALICE at LHC.

  5. Thermal neutron self-shielding correction factors for large sample instrumental neutron activation analysis using the MCNP code

    NASA Astrophysics Data System (ADS)

    Tzika, F.; Stamatelatos, I. E.

    2004-01-01

    Thermal neutron self-shielding within large samples was studied using the Monte Carlo neutron transport code MCNP. The code enabled a three-dimensional modeling of the actual source and geometry configuration including reactor core, graphite pile and sample. Neutron flux self-shielding correction factors derived for a set of materials of interest for large sample neutron activation analysis are presented and evaluated. Simulations were experimentally verified by measurements performed using activation foils. The results of this study can be applied in order to determine neutron self-shielding factors of unknown samples from the thermal neutron fluxes measured at the surface of the sample.

  6. Similar brain activation during false belief tasks in a large sample of adults with and without autism.

    PubMed

    Dufour, Nicholas; Redcay, Elizabeth; Young, Liane; Mavros, Penelope L; Moran, Joseph M; Triantafyllou, Christina; Gabrieli, John D E; Saxe, Rebecca

    2013-01-01

    Reading about another person's beliefs engages 'Theory of Mind' processes and elicits highly reliable brain activation across individuals and experimental paradigms. Using functional magnetic resonance imaging, we examined activation during a story task designed to elicit Theory of Mind processing in a very large sample of neurotypical (N = 462) individuals, and a group of high-functioning individuals with autism spectrum disorders (N = 31), using both region-of-interest and whole-brain analyses. This large sample allowed us to investigate group differences in brain activation to Theory of Mind tasks with unusually high sensitivity. There were no differences between neurotypical participants and those diagnosed with autism spectrum disorder. These results imply that the social cognitive impairments typical of autism spectrum disorder can occur without measurable changes in the size, location or response magnitude of activity during explicit Theory of Mind tasks administered to adults.

  7. Similar Brain Activation during False Belief Tasks in a Large Sample of Adults with and without Autism

    PubMed Central

    Dufour, Nicholas; Redcay, Elizabeth; Young, Liane; Mavros, Penelope L.; Moran, Joseph M.; Triantafyllou, Christina; Gabrieli, John D. E.; Saxe, Rebecca

    2013-01-01

    Reading about another person’s beliefs engages ‘Theory of Mind’ processes and elicits highly reliable brain activation across individuals and experimental paradigms. Using functional magnetic resonance imaging, we examined activation during a story task designed to elicit Theory of Mind processing in a very large sample of neurotypical (N = 462) individuals, and a group of high-functioning individuals with autism spectrum disorders (N = 31), using both region-of-interest and whole-brain analyses. This large sample allowed us to investigate group differences in brain activation to Theory of Mind tasks with unusually high sensitivity. There were no differences between neurotypical participants and those diagnosed with autism spectrum disorder. These results imply that the social cognitive impairments typical of autism spectrum disorder can occur without measurable changes in the size, location or response magnitude of activity during explicit Theory of Mind tasks administered to adults. PMID:24073267

  8. Ultrasound generation through a fiber optic delivery system using pulsed laser energy

    SciTech Connect

    Carlson, N.M.; Johnson, J.A.

    1990-01-01

    Short duration laser pulses can generate high frequency, broadband ultrasound in a material without contacting the surface. For these noncontacting techniques to be useful on the shop floor, in remote applications, and in harsh environments, a dependable delivery system must be developed. Fiber optic techniques have been used to deliver either moderate laser energy for a large number of pulses or a large laser energy for a few pulses for the purpose of generating acoustic waves. However, transmitting high energy pulses continuously through a fiber is required for practical sensing systems. Fiber optics systems are currently used for a long duration pulses (of the order of milliseconds) in laser welding applications; e.g. a welding systems developed for manufacture of headlamps uses a fiber optic delivery system. The key to the success of this welding systems is the coupling technique used to deliver laser power to the fiber. Because the pulse duration is on the order of several milliseconds, the power density in the fiber is several orders of magnitude below the power densities required for ultrasonic applications. 17 refs., 2 figs.

  9. Hot bending with a fiber coupled solid state laser

    NASA Astrophysics Data System (ADS)

    Bammer, F.; Schumi, T.; Schuöcker, D.

    2010-09-01

    For bending of brittle materials it is necessary to heat up the forming zone. This can be done with a fiber coupled solid state laser, whose beam is evenly distributed on the bending line with a beam splitter installed in the lower tool (die) of a bending press. With polarization optics the laser beam is divided there into partial beams that are evenly distributed on the bending line with lenses and prisms. A setup for a bending length of 200mm heated by a fiber-coupled 3kW Nd:YAG-laser shows the feasibility of the concept. Successful operation was shown for the Mg-alloy AZ31, which breaks during forming at room temperature, but can be well formed at temperatures in the range of 200-300°C. Other materials benefiting from this method are Ti-alloys, high-strength-Al-alloys, and high-strength-steels. Typical heating times are in the range of up to 5s and much of the heat input is generated during the bending operation where the laser continues to work. Laser Assisted Bending with a fiber coupled solid state laser is a straightforward way to perform the bending of brittle materials in a process as simple as cold bending.

  10. Thalamic stimulation largely elicits orthodromic, rather than antidromic, cortical activation in an auditory thalamocortical slice.

    PubMed

    Rose, H J; Metherate, R

    2001-01-01

    Stimulation of the medial geniculate body in an auditory thalamocortical slice elicits a short-latency current sink in the middle cortical layers, as would be expected following activation of thalamocortical relay neurons. However, corticothalamic neurons can have axon collaterals that project to the middle layers, thus, a middle-layer current sink could also result from antidromic activation of corticothalamic neurons and their axon collaterals. The likelihood of thalamic stimulation activating corticothalamic neurons would be reduced substantially if the corticothalamic pathway was not well preserved in the slice, and/or if the threshold for antidromic activation was significantly higher than for orthodromic activation. To determine the prevalence and threshold of antidromic activation, we recorded intracellularly from day 14-17 mouse brain slices containing infragranular cortical neurons while stimulating the medial geniculate or thalamocortical pathway. Antidromic spikes were confirmed by spike collision and characterized according to spike latency "jitter" and the ability to follow a high-frequency (100 Hz) stimulus train. The ability to follow a 100-Hz tetanus was a reliable indicator of antidromic activation, but both antidromic and orthodromic spikes could have low jitter. Thalamic stimulation produced antidromic activation in two of 69 infragranular cortical neurons (<3%), indicating the presence of antidromic activity, but implying a limited corticothalamic connection in the slice. Antidromic spikes in 13 additional neurons were obtained by stimulating axons in the thalamocortical pathway. The antidromic threshold averaged 214+/-40.6 microA (range 6-475 microA), over seven times the orthodromic threshold for medial geniculate-evoked responses in layer IV extracellular (28+/-5.4 microA) or intracellular (27+/-5.6 microA) recordings. We conclude that medial geniculate stimulation activates relatively few corticothalamic neurons. Conversely, low

  11. Elasticity analysis and design for large metabolic responses produced by changes in enzyme activities.

    PubMed Central

    Ortega, Fernando; Acerenza, Luis

    2002-01-01

    Metabolic control analysis has been extensively used to describe how the sensitivity properties of the component enzymes in a metabolic pathway (represented by the elasticity coefficients) determine the way in which metabolic variables respond (described by the control coefficients). Similarly, metabolic control design addresses the inverse problem of obtaining the sensitivity properties of the component enzymes that are required for the system to show a pre-established pattern of responses. These formalisms, including what is called elasticity analysis and design, were developed for small, strictly speaking infinitesimal, changes. Here we extend them to large metabolic responses. The new approach can be applied to simple two-step pathways or to any arbitrary metabolic system divided into two groups linked by one intermediate. General expressions that relate control and elasticity coefficients for large changes are derived. Concentration and flux connectivity relationships are obtained. The relationships for large changes indicate that the pattern of responses is not necessarily the same as the one obtained with the traditional infinitesimal approach, in some cases the patterns being qualitatively different. The general analysis is used to study the control of ketogenesis in rat liver mitochondria, starting from data available in the literature. The control profile of the pathway subject to large changes shows both quantitative and qualitative differences from the one obtained from an analysis that is performed with infinitesimal coefficients. This exemplifies the type of errors that may be introduced when drawing conclusions about large metabolic responses from results obtained with an infinitesimal treatment. PMID:12084013

  12. Complex active regions as the main source of extreme and large solar proton events

    NASA Astrophysics Data System (ADS)

    Ishkov, V. N.

    2013-12-01

    A study of solar proton sources indicated that solar flare events responsible for ≥2000 pfu proton fluxes mostly occur in complex active regions (CARs), i.e., in transition structures between active regions and activity complexes. Different classes of similar structures and their relation to solar proton events (SPEs) and evolution, depending on the origination conditions, are considered. Arguments in favor of the fact that sunspot groups with extreme dimensions are CARs are presented. An analysis of the flare activity in a CAR resulted in the detection of "physical" boundaries, which separate magnetic structures of the same polarity and are responsible for the independent development of each structure.

  13. Role of Delays in Shaping Spatiotemporal Dynamics of Neuronal Activity in Large Networks

    SciTech Connect

    Roxin, Alex; Brunel, Nicolas; Hansel, David

    2005-06-17

    We study the effect of delays on the dynamics of large networks of neurons. We show that delays give rise to a wealth of bifurcations and to a rich phase diagram, which includes oscillatory bumps, traveling waves, lurching waves, standing waves arising via a period-doubling bifurcation, aperiodic regimes, and regimes of multistability. We study the existence and the stability of the various dynamical patterns analytically and numerically in a simplified rate model as a function of the interaction parameters. The results derived in that framework allow us to understand the origin of the diversity of dynamical states observed in large networks of spiking neurons.

  14. Associations between Grades and Physical Activity and Food Choices: Results from YRBS from a Large Urban School District

    ERIC Educational Resources Information Center

    Snelling, Anastasia; Belson, Sarah Irvine; Beard, Jonathan; Young, Kathleen

    2015-01-01

    Purpose: The purpose of this paper is to explore the relationship between television viewing time, physical activity level, food consumption patterns, and academic performance of adolescents in a large urban school district in the USA where health disparities are prevalent, particularly among minority residents. Design/Methodology/Approach: The…

  15. Use of asymptotic analysis of the large activation-energy limit to compare graphical methods of treating thermogravimetry data

    Treesearch

    A. Broido; F.A. Williams

    1973-01-01

    An earIier numerical analysis showed that the second approximate method of Horotitz and Metzger can be rendered exceedingly accurate for reduction of thermo-gravimetry data. It is demonstrated here that this result can be justified on the basis of an asymptotic expansion with a nondimensional activation energy as the large parameter. The order of magnitude of the error...

  16. Silent and Vocal Students in a Large Active Learning Chemistry Classroom: Comparison of Performance and Motivational Factors

    ERIC Educational Resources Information Center

    Obenland, Carrie A.; Munson, Ashlyn H.; Hutchinson, John S.

    2013-01-01

    Active learning is becoming more prevalent in large science classrooms, and this study shows the impact on performance of being vocal during Socratic questioning in a General Chemistry course. 800 college students over a two year period were given a pre and post-test using the Chemistry Concept Reasoning Test. The pre-test results showed that…

  17. Associations between Grades and Physical Activity and Food Choices: Results from YRBS from a Large Urban School District

    ERIC Educational Resources Information Center

    Snelling, Anastasia; Belson, Sarah Irvine; Beard, Jonathan; Young, Kathleen

    2015-01-01

    Purpose: The purpose of this paper is to explore the relationship between television viewing time, physical activity level, food consumption patterns, and academic performance of adolescents in a large urban school district in the USA where health disparities are prevalent, particularly among minority residents. Design/Methodology/Approach: The…

  18. Implementation of Lifestyle Modification Program Focusing on Physical Activity and Dietary Habits in a Large Group, Community-Based Setting

    ERIC Educational Resources Information Center

    Stoutenberg, Mark; Falcon, Ashley; Arheart, Kris; Stasi, Selina; Portacio, Francia; Stepanenko, Bryan; Lan, Mary L.; Castruccio-Prince, Catarina; Nackenson, Joshua

    2017-01-01

    Background: Lifestyle modification programs improve several health-related behaviors, including physical activity (PA) and nutrition. However, few of these programs have been expanded to impact a large number of individuals in one setting at one time. Therefore, the purpose of this study was to determine whether a PA- and nutrition-based lifestyle…

  19. Objectively measured physical activity and fat mass in a large cohort of children.

    PubMed

    Ness, Andy R; Leary, Sam D; Mattocks, Calum; Blair, Steven N; Reilly, John J; Wells, Jonathan; Ingle, Sue; Tilling, Kate; Smith, George Davey; Riddoch, Chris

    2007-03-01

    Previous studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity. We carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01-0.13, p-value for trend <0.0001) in boys and 0.36 (95% CI 0.17-0.74, p-value for trend = 0.006) in girls. We demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity.

  20. Objectively Measured Physical Activity and Fat Mass in a Large Cohort of Children

    PubMed Central

    Ness, Andy R; Leary, Sam D; Mattocks, Calum; Blair, Steven N; Reilly, John J; Wells, Jonathan; Ingle, Sue; Tilling, Kate; Smith, George Davey; Riddoch, Chris

    2007-01-01

    Background Previous studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity. Methods and Findings We carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01–0.13, p-value for trend <0.0001) in boys and 0.36 (95% CI 0.17–0.74, p-value for trend = 0.006) in girls. Conclusions We demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity. PMID:17388663

  1. Active Learning in Large Classes: Can Small Interventions Produce Greater Results than Are Statistically Predictable?

    ERIC Educational Resources Information Center

    Adrian, Lynne M.

    2010-01-01

    Six online postings and six one-minute papers were added to an introductory first-year class, forming 5 percent of the final grade, but represented significant intervention in class functioning and amount of active learning. Active learning produced results in student performance beyond the percentage of the final grade it constituted. (Contains 1…

  2. Transforming a Large-Lecture Course into an Active, Engaging, and Collaborative Learning Environment

    ERIC Educational Resources Information Center

    Stoerger, Sharon; Krieger, Denise

    2016-01-01

    Traditionally, a large lecture hall course follows a teacher-centered approach to instruction. This was the case for the "gateway" course in the undergraduate Information Technology and Informatics (ITI) major in the School of Communication and Information at Rutgers, The State University of New Jersey. This paper describes the journey…

  3. Transforming a Large-Lecture Course into an Active, Engaging, and Collaborative Learning Environment

    ERIC Educational Resources Information Center

    Stoerger, Sharon; Krieger, Denise

    2016-01-01

    Traditionally, a large lecture hall course follows a teacher-centered approach to instruction. This was the case for the "gateway" course in the undergraduate Information Technology and Informatics (ITI) major in the School of Communication and Information at Rutgers, The State University of New Jersey. This paper describes the journey…

  4. Sandia Laboratories in-house activities in support of solar thermal large power applications

    NASA Technical Reports Server (NTRS)

    Mar, R. W.

    1980-01-01

    The development of thermal energy storage subsystems for solar thermal large power applications is described. The emphasis is on characterizing the behavior of molten nitrate salts with regard to thermal decomposition, environmental interactions, and corrosion. Electrochemical techniques to determine the ionic species in the melt and for use in real time studies of corrosion are also briefly discussed.

  5. Measuring Student Interactions Using Networks: Insights into the Learning Community of a Large Active Learning Course

    ERIC Educational Resources Information Center

    Buchenroth-Martin, Cynthia; DiMartino, Trevor; Martin, Andrew P.

    2017-01-01

    Collaborative learning in small groups is commonly implemented as a part of student-centered curricula. In large-enrollment courses, details of the interactions among students as a consequence of working in collaborative groups are often unknown but are important because how students interact influences the effectiveness of peer learning. We…

  6. An Active-Learning Approach to Fostering Understanding of Research Methods in Large Classes

    ERIC Educational Resources Information Center

    LaCosse, Jennifer; Ainsworth, Sarah E.; Shepherd, Melissa A.; Ent, Michael; Klein, Kelly M.; Holland-Carter, Lauren A.; Moss, Justin H.; Licht, Mark; Licht, Barbara

    2017-01-01

    The current investigation tested the effectiveness of an online student research project designed to supplement traditional methods (e.g., lectures, discussions, and assigned readings) of teaching research methods in a large-enrollment Introduction to Psychology course. Over the course of the semester, students completed seven assignments, each…

  7. Measuring Student Interactions Using Networks: Insights into the Learning Community of a Large Active Learning Course

    ERIC Educational Resources Information Center

    Buchenroth-Martin, Cynthia; DiMartino, Trevor; Martin, Andrew P.

    2017-01-01

    Collaborative learning in small groups is commonly implemented as a part of student-centered curricula. In large-enrollment courses, details of the interactions among students as a consequence of working in collaborative groups are often unknown but are important because how students interact influences the effectiveness of peer learning. We…

  8. Calcium-mediated fusion to produce ultra large osmotically active mitochondrial inner membranes of controlled protein density.

    PubMed

    Chazotte, B; Wu, E S; Höchli, M; Hackenbrock, C R

    1985-08-08

    We have developed a new membrane fusion method which produces ultra large, spherical mitochondrial inner membranes attached to microscope slides. The fused inner membranes measured up to 200 microns in diameter. The technique fuses native inner membranes as well as inner membranes in which the protein density has been varied by enriching with exogenous phospholipid. The fusion process is accomplished through the use of calcium, low pH and elevated temperature. Characterization of the fused membranes was carried out using phase, fluorescence, and freeze-fracture electron microscopy. These ultra large, fused inner membranes were found to model the inner membranes from which they were formed. The fused inner membranes were found to be osmotically active and are large enough for measuring the lateral diffusion of membrane components by fluorescence recovery after photobleaching and are large enough for microelectrode impalement.

  9. Active carbon electrode fabricated via large-scale coating-transfer process for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Guo, Hui; Liu, Zheng; Li, Hengyue; Wu, Han; Zhang, Chujun; Yang, Junliang; Chen, Xiaohua

    2017-07-01

    Electrodes play important roles on the performance of supercapacitors, and low-cost, large-scale fabrication of high-performance electrodes is closely related to the actual application of supercapacitors. Herein, a low-cost, large-scale coating-transfer method was developed to fabricate high-performance carbon electrodes with excellent homogeneity, high conductivity, and large surface area. Symmetric button supercapacitors using active carbon as the electrode material fabricated via coating-transfer process exhibit good specific capacitance up to 211 F g-1 at 0.1 A g-1 in 1 M neutral aqueous electrolyte, which shows 40% improvement as compared with convention rolling process. Furthermore, these supercapacitors present high repeatability and excellent performance stability. The research demonstrates that the low-cost, large-scale coating-transfer process shows great potentials in practical application for fabricating high-performance supercapacitors.

  10. Ionic current correlations underlie the global tuning of large numbers of neuronal activity attributes.

    PubMed

    Zhao, Shunbing; Golowasch, Jorge

    2012-09-26

    Ionic conductances in identified neurons are highly variable. This poses the crucial question of how such neurons can produce stable activity. Coexpression of ionic currents has been observed in an increasing number of neurons in different systems, suggesting that the coregulation of ionic channel expression, by thus linking their variability, may enable neurons to maintain relatively constant neuronal activity as suggested by a number of recent theoretical studies. We examine this hypothesis experimentally using the voltage- and dynamic-clamp techniques to first measure and then modify the ionic conductance levels of three currents in identified neurons of the crab pyloric network. We quantify activity by measuring 10 different attributes (oscillation period, spiking frequency, etc.), and find linear, positive and negative relationships between conductance pairs and triplets that can enable pyloric neurons to maintain activity attributes invariant. Consistent with experimental observations, some of the features most tightly regulated appear to be phase relationships of bursting activity. We conclude that covariation (and probably a tightly controlled coregulation) of ionic conductances can help neurons maintain certain attributes of neuronal activity invariant while at the same time allowing conductances to change over wide ranges in response to internal or environmental inputs and perturbations. Our results also show that neurons can tune neuronal activity globally via coordinate expression of ion currents.

  11. Activity Determinants of Helical Antimicrobial Peptides: A Large-Scale Computational Study

    PubMed Central

    He, Yi; Lazaridis, Themis

    2013-01-01

    Antimicrobial peptides (AMPs), produced by a wide range of organisms, have attracted attention due to their potential use as novel antibiotics. The majority of these peptides are cationic and are thought to function by permeabilizing the bacterial membrane, either by making pores or by dissolving it (‘carpet’ model). A key hypothesis in the literature is that antimicrobial and hemolytic activity correlate with binding affinity to anionic and zwitterionic membranes, respectively. Here we test this hypothesis by using binding free energy data collected from the literature and theoretical binding energies calculated from implicit membrane models for 53 helical AMPs. We indeed find a correlation between binding energy and biological activity, depending on membrane anionic content: antibacterial activity correlates best with transfer energy to membranes with anionic lipid fraction higher than 30% and hemolytic activity correlates best with transfer energy to a 10% anionic membrane. However, the correlations are weak, with correlation coefficient up to 0.4. Weak correlations of the biological activities have also been found with other physical descriptors of the peptides, such as surface area occupation, which correlates significantly with antibacterial activity; insertion depth, which correlates significantly with hemolytic activity; and structural fluctuation, which correlates significantly with both activities. The membrane surface coverage by many peptides at the MIC is estimated to be much lower than would be required for the ‘carpet’ mechanism. Those peptides that are active at low surface coverage tend to be those identified in the literature as pore-forming. The transfer energy from planar membrane to cylindrical and toroidal pores was also calculated for these peptides. The transfer energy to toroidal pores is negative in almost all cases while that to cylindrical pores is more favorable in neutral than in anionic membranes. The transfer energy to pores

  12. A large catalog of young active RAVE stars in the Solar neighborhood

    NASA Astrophysics Data System (ADS)

    Žerjal, Maruša; Zwitter, Tomaž; Matijevič, Gal; RAVE Collaboration

    2017-10-01

    The catalog of 38,000 chromospherically active RAVE dwarfs represents one of the largest samples of young active solar-like and later-type single field stars in the Solar neighbourhood. It was established from the unbiased magnitude limited RAVE Survey using an unsupervised stellar classification algorithm based merely on stellar fluxes (Ca II infrared triplet). Using a newly-calibrated age-activity relation, ~15,000 active stars are estimated to be younger than 1 Gyr. Almost 2000 stars are presumably younger than ~100 Myr and possibly still in the pre-main sequence phase, the latter being supported by their significant offset from the main sequence in the N UV - V versus J - K space. 16,000 stars from the sample have positional and velocity vectors available (using TGAS parallaxes and proper motions and radial velocities from RAVE).

  13. Large litters rearing changes brain expression of GLUT3 and acetylcholinesterase activity in adult rats.

    PubMed

    de Vasconcelos, Vivian Sarmento; Machado, Sonia Salgueiro; Guedes, Rubem Carlos Araújo; Bandeira, Bruno Carneiro; Ximenes-da-Silva, Adriana

    2012-09-06

    Effects of malnutrition in the brain are more pronounced during the period of growth spurt, corresponding to the suckling in rodents. Neuronal glucose transporter GLUT3 expression and acetylcholinesterase activity were studied in the brain of adult young rats (84 days old) suckled in litters formed by 6 (control group) or 12 pups (malnourished group). In the adult rats, brain weight, blood glucose levels and GLUT3 expression were decreased in malnourished group (5%, 18%, 58%, respectively, P<0.001, Student's t test) compared to the control. Increased activity of acetylcholinesterase was found in cerebral cortex homogenates and a significant interaction (P=0.019, ANOVA two-way, Tukey's test) was found between nutritional state and homogenate fraction. In summary, malnutrition during suckling period decreased GLUT3 expression and increased acetylcholinesterase activity in the rat brain that could contribute to possible cognitive deficits and changes of brain metabolic activity. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  14. A method for determining Am-241 activity for large area contamination.

    PubMed

    Wilhelm, Emilien; Arbor, Nicolas; Gutierrez, Sébastien; Ménard, Stéphanie; Nourreddine, Abdel-Mjid

    2017-01-01

    Airborne gamma-ray spectrometry system HELINUC™ is used for different missions. Although well-developed for estimation of high energy emitters' activity, it is rarely used for low energy emitters. A new method for the determination of Am-241 activity over extended sites based both on statistical analysis of spectra and deconvolution of Am-241 signal with a reference library is presented. Results show a lowering of the detection threshold and a good agreement with ground level measurements.

  15. Disruption of Prefrontal Cortex Large Scale Neuronal Activity by Different Classes of Psychotomimetic Drugs

    PubMed Central

    Wood, Jesse; Kim, Yunbok; Moghaddam, Bita

    2012-01-01

    In the absence of overt cellular pathology but profound perceptual disorganization and cognitive deficits, schizophrenia is increasingly considered a disorder of neural coordination. Thus, different causal factors can similarly interrupt the dynamic function of neuronal ensembles and networks, in particular in the prefrontal cortex (PFC), leading to behavioral disorganization. The importance of establishing preclinical biomarkers for this aberrant function has prompted investigations into the nature of psychotomimetic drug effects on PFC neuronal activity. The drugs used in this context include serotonergic hallucinogens, amphetamine, and NMDA receptor antagonists. A prominent line of thinking is that these drugs create psychotomimetic states by similarly disinhibiting the activity of PFC pyramidal neurons. In the present study we did not find evidence in support of this mechanism in PFC subregions of freely moving rats. Whereas the NMDA receptor antagonist MK801 increased PFC population activity, the serotonergic hallucinogen DOI dose-dependently decreased population activity. Amphetamine did not strongly affect this measure. Despite different effects on the direction of change in activity, all three drugs caused similar net disruptions of population activity and modulated gamma oscillations. We also observed reduced correlations between spikerate and LFP power selectively in the gamma band suggesting that these drugs disconnect spike-discharge from PFC gamma oscillators. Gamma band oscillations support cognitive functions affected in schizophrenia. These findings provide insight into mechanisms that may lead to cortical processing deficits in schizophrenia and provide a novel electrophysiological approach for phenotypic characterization of animal models of this disease. PMID:22378875

  16. Active Removal of Large Debris: System Approach of Desorbiting Concepts and Technological Issues

    NASA Astrophysics Data System (ADS)

    Couzin, Patrice; Rembala, Richard; Teti, Frank; Bakouche, Charles; Billot, Carole

    2013-08-01

    The threat induced by large space debris, dead satellites or rocket bodies, in Low Earth Orbit has been identified years ago. A first part of the Orbital Transfer Vehicle (OTV) study was dedicated to identify mission architectures that can fulfil the objective to eliminate the necessary number of critical debris. Those potential solutions and architectures have been compared taking into account cost considerations. The present paper reports the first results of the OTV step2 study funded by CNES that addresses different solutions for large debris removal. It compares different desorbiting concepts from selected single to multiple debris complying with the Space Law, i.e. able to ensure controlled re entries. Different capture options are presented, including sensors needs and an analysis of the problems posed by different solutions. The overall performances of the concepts are compared, showing the adequacy, the limits of each solutions and application domains.

  17. Transport in organic semiconductors in large electric fields: From thermal activation to field emission

    NASA Astrophysics Data System (ADS)

    Worne, J. H.; Anthony, J. E.; Natelson, D.

    2010-02-01

    Understanding charge transport in organic semiconductors in large electric fields is relevant to many applications. We present transport measurements in organic field-effect transistors based on poly(3-hexylthiophene) and 6,13-bis(triisopropyl-silylethynyl) (TIPS) pentacene with short channels, from room temperature down to 4.2 K. Near 300 K transport in both systems is well described by thermally assisted hopping with Poole-Frenkel-type enhancement of the mobility. At low temperatures and large gate voltages, transport in both materials becomes nearly temperature independent, crossing over into field-driven tunneling. These data, particularly in TIPS-pentacene, show that great caution must be exercised when considering more exotic (e.g., Tomonaga-Luttinger liquid) interpretations of transport.

  18. Active Control of Adaptive Optics System in a Large Segmented Mirror Telescope

    DTIC Science & Technology

    2012-01-01

    expensive. Hubble Space Telescope has a primary mirror of 2.4 m diameter, but it is difficult to further extend the size of the mirror because no launch...Method I INTRODUCTION In optical systems used for imagery, such as telescopes for astronomy or surveillance of the earth surface from the space , the...possible resolution of the image. For telescopes in the space , on the other hand, launching a large solid optical mirror is very challenging and also

  19. Large Area Active Brazing of Multi-tile Ceramic-Metal Structures

    DTIC Science & Technology

    2012-05-01

    fabricating a combination of lightweight ceramics and metals is complicated by the need to bond these very dissimilar materials together. For severe... steels ) and form strong, metallurgical bonds. However, the high processing temperatures result in large strain (stress) build-up from the inherent... dissimilar materials together. For severe applications, a strong bond between the ceramic and metal is required. One option for achieving this strong

  20. Active control of adaptive optics system in a large segmented mirror telescope

    NASA Astrophysics Data System (ADS)

    Nagashima, M.; Agrawal, B. N.

    2014-02-01

    For a large adaptive optics system such as a large segmented mirror telescope (SMT), it is often difficult, although not impossible, to directly apply common multi-input multi-output (MIMO) controller design methods due to the computational burden imposed by the large dimension of the system model. In this article, a practical controller design method is proposed which significantly reduces the system dimension for a system where the dimension required to represent the dynamics of the plant is much smaller than the dimension of the full plant model. The proposed method decouples the dynamic and static parts of the plant model by a modal decomposition technique to separately design a controller for each part. Two controllers are then combined using the so-called sensitivity decoupling method so that the resulting feedback loop becomes the superposition of the two individual feedback loops of the dynamic and static parts. A MIMO controller was designed by the proposed method using the H ∞ loop-shaping technique for an SMT model to be compared with other controllers proposed in the literature. Frequency-domain analysis and time-domain simulation results show the superior performance of the proposed controller.

  1. Smooth muscle relaxation and activation of the large conductance Ca++ – activated K+ (BKCa) channel by novel oestrogens

    PubMed Central

    Maher, J; Hunter, A C; Mabley, J G; Lippiat, J; Allen, M C

    2013-01-01

    Background and Purpose Oestrogens can interact directly with membrane receptors and channels and can activate vascular BKCa channels. We hypothesized that novel oestrogen derivatives could relax smooth muscle by an extracllular effect on the α and β1 subunits of the BKCa channel, rather than at an intracellular site. Experimental Approach We studied the effects of novel oestrogens on the tension of pre-contracted isolated rat aortic rings, and on the electrophysiological properties of HEK 293 cells expressing the hSloα or hSloα+β1 subunits. Two of the derivatives incorporated a quaternary ammonium side-chain making them membrane impermeable. Key Results Oestrone, oestrone oxime and Quat DME-oestradiol relaxed pre-contracted rat aorta, but only Quat DME-oestradiol-induced relaxation was iberiotoxin sensitive. However, only potassium currents recorded in HEK 293 cells over-expressing both hSloα and hSloβ1 were activated by oestrone, oestrone oxime and Quat DME-oestradiol. Conclusion and Implications The novel oestrogens were able to relax smooth muscle, but through different mechanisms. In particular, oestrone oxime required the presence of the endothelium to exert much of its effect, whilst Quat DME-oestradiol depended both on NO and BKCa channel activation. The activation of BKCa currents in HEK 293 cells expressing hSloα+β1 by Quat DME-oestradiol is consistent with an extracellular binding site between the two subunits. The binding site resides between the extracellular N terminal of the α subunit and the extracellular loop between TM1 and 2 of the β1 subunit. Membrane-impermeant Quat DME-oestradiol lacks an exchangeable hydrogen on the A ring obviating antioxidant activity. PMID:23586466

  2. Pregnancy upregulates large-conductance Ca(2+)-activated K(+) channel activity and attenuates myogenic tone in uterine arteries.

    PubMed

    Hu, Xiang-Qun; Xiao, Daliao; Zhu, Ronghui; Huang, Xiaohui; Yang, Shumei; Wilson, Sean; Zhang, Lubo

    2011-12-01

    Uterine vascular tone significantly decreases whereas uterine blood flow dramatically increases during pregnancy. However, the complete molecular mechanisms remain elusive. We hypothesized that increased Ca(2+)-activated K(+) (BK(Ca)) channel activity contributes to the decreased myogenic tone of uterine arteries in pregnancy. Resistance-sized uterine arteries were isolated from nonpregnant and near-term pregnant sheep. Electrophysiological studies revealed a greater whole-cell K(+) current density in pregnant compared with nonpregnant uterine arteries. Tetraethylammonium and iberiotoxin inhibited K(+) currents to the same extent in uterine arterial myocytes. The BK(Ca) channel current density was significantly increased in pregnant uterine arteries. In accordance, tetraethylammonium significantly increased pressure-induced myogenic tone in pregnant uterine arteries and abolished the difference in myogenic responses between pregnant and nonpregnant uterine arteries. Activation of protein kinase C produced a similar effect to tetraethylammonium by inhibiting BK(Ca) channel activity and increasing myogenic tone in pregnant uterine arteries. Chronic treatment of nonpregnant uterine arteries with physiologically relevant concentrations of 17β-estradiol and progesterone caused a significant increase in the BK(Ca) channel current density. Western blot analyses demonstrated a significant increase of the β1, but not α, subunit of BK(Ca) channels in pregnant uterine arteries. In accordance, steroid treatment of nonpregnant uterine arteries resulted in an upregulation of the β1, but not α, subunit expression. The results indicate that the steroid hormone-mediated upregulation of the β1 subunit and BK(Ca) channel activity may play a key role in attenuating myogenic tone of the uterine artery in pregnancy.

  3. Tumor microenvironment in diffuse large B-cell lymphoma: Matrixmetalloproteinases activation is mediated by osteopontin overexpression.

    PubMed

    Malaponte, Grazia; Hafsi, Sameh; Polesel, Jerry; Castellano, Giancarlo; Spessotto, Paola; Guarneri, Claudio; Canevari, Silvana; Signorelli, Santo S; McCubrey, James A; Libra, Massimo

    2016-03-01

    Non-Hodgkin lymphomas (NHL) are a heterogeneous group of lymphoproliferative malignancies with variable patterns of behavior and responses to therapy. NHL development and invasion depend on multiple interactions between tumor cells and non-neoplastic cells. Such interactions are usually modulated by several cytokines. Accordingly, it was demonstrated that matrix-metalloproteinase (MMP)-2 and MMP-9 were activated in human lymphoid cell lines by interleukin-6 (IL-6). The activation of these enzymes is associated with tumor invasion and metastasis in human cancers. MMPs are also activated in several cancers by osteopontin (OPN), a secreted glycoprotein that regulates cell adhesion, migration, and survival. However, it is still unclear if MMPs play a role in NHL development and if their activation is determined by OPN and/or IL-6. In the present study, two groups of 78 NHL patients and 95 healthy donors were recruited for the analysis of OPN, MMP-2, MMP-9 and IL-6.Significant higher circulating levels of MMP-2, MMP-9, OPN and IL-6 were observed in NHL patients when compared to healthy donors. Similar data were obtained by analyzing the activity of both MMP-2 and MMP-9. The multivariate regression model indicates that, in both NHL cases and healthy donors, OPN is associated with the increase of MMP-2 and MMP-9 levels independently of IL-6. These data were first confirmed by “in silico” analyses and then by “in vitro” experiments conducted on peripheral blood mononuclear cells randomly selected from both NHL patients and healthy donors.Overall, our data suggest that the activation of MMPs in NHL development is mostly associated with OPN. However, IL-6 may play an important role in the lymphomagenesis through the activation of other molecular pathways. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.

  4. Holographic fiber bundle system for patterned optogenetic activation of large-scale neuronal networks

    PubMed Central

    Farah, Nairouz; Levinsky, Alexandra; Brosh, Inbar; Kahn, Itamar; Shoham, Shy

    2015-01-01

    Abstract. Optogenetic perturbation has become a fundamental tool in controlling activity in neurons. Used to control activity in cell cultures, slice preparations, anesthetized and awake behaving animals, optical control of cell-type specific activity enables the interrogation of complex systems. A remaining challenge in developing optical control tools is the ability to produce defined light patterns such that power-efficient, precise control of neuronal populations is obtained. Here, we describe a system for patterned stimulation that enables the generation of structured activity in neurons by transmitting optical patterns from computer-generated holograms through an optical fiber bundle. The system couples the optical system to versatile fiber bundle configurations, including coherent or incoherent bundles composed of hundreds of up to several meters long fibers. We describe the components of the system, a method for calibration, and a detailed power efficiency and spatial specificity quantification. Next, we use the system to precisely control single-cell activity as measured by extracellular electrophysiological recordings in ChR2-expressing cortical cell cultures. The described system complements recent descriptions of optical control systems, presenting a system suitable for high-resolution spatiotemporal optical control of wide-area neural networks in vitro and in vivo, yielding a tool for precise neural system interrogation. PMID:26793741

  5. Lessons learned with the Active Phasing Experiment: comparison of four optical phasing sensors on a segmented Very Large Telescope

    NASA Astrophysics Data System (ADS)

    Gonte, F.; Surdej, I.

    The adaptive optics capabilities are strongly limited by the quality of the phasing of the primary mirror of the extremely large telescope. Up to date, the Keck telescopes are the only segmented telescope phased with a quality enabling the application of adaptive optics. The Active Phasing Experiment has been installed at the Namyth focus of the Very Large Telescope Melipal during the last 6 months. Its purpose is to understand and compare different technological concepts for an optical phasing sensor dedicated to the European Extremely Large Telescope. The pupil of the telescope is segmented in 61 hexagonal segments by projecting it on an Active Segmented Mirror. The ASM is controlled by a dual wavenlength interferometer made by Fogale Nanotech with a nanometric precision. The segmented pupil is distributed in parallel to four optical phasing sensors. They are a pyramid sensor, a curvature sensor, a phase filtering sensor and a ShackHartmann sensor. They have been developed respectively by Istituto Nazionale di Astrofisica in Florenze, Instituto Astrofisica Canarias in Tenerife, Laboratoire d'Astrophysique de Marseille and ESO. The global behaviour of the optical phasing sensors will be described and preliminary results of the Active Phasing Experiments obtained on sky will be explained. The extrapolation of the results to the EELT and the potential consequences for the adaptive optics will be given. The Active Phasing Experiment has been financed by the European Union and the European Southern Observatory via the Sixth European Union Framework Program for Research and Technological Development under the contract number 011863.

  6. Measuring activity in the ubiquitin-proteasome system: From large scale discoveries to single cells analysis

    PubMed Central

    Melvin, Adam T.; Woss, Gregery S.; Park, Jessica H.; Waters, Marcey L.; Allbritton, Nancy L.

    2013-01-01

    The ubiquitin proteasome system (UPS) is the primary pathway responsible for the recognition and degradation of misfolded, damaged, or tightly regulated proteins in addition to performing essential roles in DNA repair, cell cycle regulation, cell migration, and the immune response. While traditional biochemical techniques have proven useful in the identification of key proteins involved in this pathway, the implementation of novel reporters responsible for measuring enzymatic activity of the UPS have provided valuable insight into the effectiveness of therapeutics and role of the UPS in various human diseases such as multiple myeloma and Huntington’s disease. These reporters, usually consisting of a recognition sequences fused to an analytical handle, are designed to specifically evaluate enzymatic activity of certain members of the UPS including the proteasome, E3 ubiquitin ligases, and deubiquitinating enzymes (DUBs). This review highlights the more commonly used reporters employed in a variety of scenarios ranging from high-throughput screening of novel inhibitors to single cell microscopy techniques measuring E3 ligase or proteasome activity. Finally, recent work is presented highlighting the development of novel degron-based substrate designed to overcome the limitations of current reporting techniques in measuring E3 ligase and proteasome activity in patient samples. PMID:23686610

  7. Measuring activity in the ubiquitin-proteasome system: from large scale discoveries to single cells analysis.

    PubMed

    Melvin, Adam T; Woss, Gregery S; Park, Jessica H; Waters, Marcey L; Allbritton, Nancy L

    2013-09-01

    The ubiquitin-proteasome system (UPS) is the primary pathway responsible for the recognition and degradation of misfolded, damaged, or tightly regulated proteins in addition to performing essential roles in DNA repair, cell cycle regulation, cell migration, and the immune response. While traditional biochemical techniques have proven useful in the identification of key proteins involved in this pathway, the implementation of novel reporters responsible for measuring enzymatic activity of the UPS has provided valuable insight into the effectiveness of therapeutics and role of the UPS in various human diseases such as multiple myeloma and Huntington's disease. These reporters, usually consisting of a recognition sequence fused to an analytical handle, are designed to specifically evaluate enzymatic activity of certain members of the UPS including the proteasome, E3 ubiquitin ligases, and deubiquitinating enzymes. This review highlights the more commonly used reporters employed in a variety of scenarios ranging from high-throughput screening of novel inhibitors to single cell microscopy techniques measuring E3 ligase or proteasome activity. Finally, a recent study is presented highlighting the development of a novel degron-based substrate designed to overcome the limitations of current reporting techniques in measuring E3 ligase and proteasome activity in patient samples.

  8. Thermal activation of ‘allosteric-like’ large-scale motions in a eukaryotic Lactate Dehydrogenase

    PubMed Central

    Katava, Marina; Maccarini, Marco; Villain, Guillaume; Paciaroni, Alessandro; Sztucki, Michael; Ivanova, Oxana; Madern, Dominique; Sterpone, Fabio

    2017-01-01

    Conformational changes occurring during the enzymatic turnover are essential for the regulation of protein functionality. Individuating the protein regions involved in these changes and the associated mechanical modes is still a challenge at both experimental and theoretical levels. We present here a detailed investigation of the thermal activation of the functional modes and conformational changes in a eukaryotic Lactate Dehydrogenase enzyme (LDH). Neutron Spin Echo spectroscopy and Molecular Dynamics simulations were used to uncover the characteristic length- and timescales of the LDH nanoscale motions in the apo state. The modes involving the catalytic loop and the mobile region around the binding site are activated at room temperature, and match the allosteric reorganisation of bacterial LDHs. In a temperature window of about 15 degrees, these modes render the protein flexible enough and capable of reorganising the active site toward reactive configurations. On the other hand an excess of thermal excitation leads to the distortion of the protein matrix with a possible anti-catalytic effect. Thus, the temperature activates eukaryotic LDHs via the same conformational changes observed in the allosteric bacterial LDHs. Our investigation provides an extended molecular picture of eukaryotic LDH’s conformational landscape that enriches the static view based on crystallographic studies alone. PMID:28112231

  9. Thermal activation of 'allosteric-like' large-scale motions in a eukaryotic Lactate Dehydrogenase.

    PubMed

    Katava, Marina; Maccarini, Marco; Villain, Guillaume; Paciaroni, Alessandro; Sztucki, Michael; Ivanova, Oxana; Madern, Dominique; Sterpone, Fabio

    2017-01-23

    Conformational changes occurring during the enzymatic turnover are essential for the regulation of protein functionality. Individuating the protein regions involved in these changes and the associated mechanical modes is still a challenge at both experimental and theoretical levels. We present here a detailed investigation of the thermal activation of the functional modes and conformational changes in a eukaryotic Lactate Dehydrogenase enzyme (LDH). Neutron Spin Echo spectroscopy and Molecular Dynamics simulations were used to uncover the characteristic length- and timescales of the LDH nanoscale motions in the apo state. The modes involving the catalytic loop and the mobile region around the binding site are activated at room temperature, and match the allosteric reorganisation of bacterial LDHs. In a temperature window of about 15 degrees, these modes render the protein flexible enough and capable of reorganising the active site toward reactive configurations. On the other hand an excess of thermal excitation leads to the distortion of the protein matrix with a possible anti-catalytic effect. Thus, the temperature activates eukaryotic LDHs via the same conformational changes observed in the allosteric bacterial LDHs. Our investigation provides an extended molecular picture of eukaryotic LDH's conformational landscape that enriches the static view based on crystallographic studies alone.

  10. Rotation, activity, and stellar obliquities in a large uniform sample of Kepler solar analogs

    NASA Astrophysics Data System (ADS)

    Buzasi, Derek; Lezcano, Andy; Preston, Heather L.

    2016-10-01

    In this study, we undertook a deep photometric examination of a narrowly-defined sample of solar analogs in the Kepler field, with the goals of producing a uniform and statistically meaningful sample of such stars, comparing the properties of planet hosts to those of the general stellar population, and examining the behavior of rotation and photometric activity among stars with similar overall physical parameters. We successfully derived photometric activity indicators and rotation periods for 95 planet hosts (Kepler objects of interest [KOIs]) and 954 solar analogs without detected planets; 573 of these rotation periods are reported here for the first time. Rotation periods average roughly 20 d, but the distribution has a wide dispersion, with a tail extending to P > 35 d which appears to be inconsistent with published gyrochronological relations. We observed a weak rotation-activity relation for stars with rotation periods less than about 12 d; for slower rotators, the relation is dominated by scatter. However, we are able to state that the solar activity level derived from Virgo data is consistent with the majority of stars with similar rotation periods in our sample. Finally, our KOI sample is consistently approximately 0.3 dex more variable than our non-KOIs; we ascribe the difference to a selection effect due to low orbital obliquity in the planet-hosting stars and derive a mean obliquity for our sample of χ = 6+5°-6, similar to that seen in the solar system.

  11. Quantifying the fingerprint descriptor dependence of structure-activity relationship information on a large scale.

    PubMed

    Dimova, Dilyana; Stumpfe, Dagmar; Bajorath, Jürgen

    2013-09-23

    It is well-known that different molecular representations, e.g., graphs, numerical descriptors, fingerprints, or 3D models, change the numerical results of molecular similarity calculations. Because the assessment of structure-activity relationships (SARs) requires similarity and potency comparisons of active compounds, this representation dependence inevitably also affects SAR analysis. But to what extent? How exactly does SAR information change when alternative fingerprints are used as descriptors? What is the proportion of active compounds with substantial changes in SAR information induced by different fingerprints? To provide answers to these questions, we have quantified changes in SAR information across many different compound classes using six different fingerprints. SAR profiling was carried out on 128 target-based data sets comprising more than 60,000 compounds with high-confidence activity annotations. A numerical measure of SAR discontinuity was applied to assess SAR information on a per compound basis. For ~70% of all test compounds, changes in SAR characteristics were detected when different fingerprints were used as molecular representations. Moreover, the SAR phenotype of ~30% of the compounds changed, and distinct fingerprint-dependent local SAR environments were detected. The fingerprints we compared were found to generate SAR models that were essentially not comparable. Atom environment and pharmacophore fingerprints produced the largest differences in compound-associated SAR information. Taken together, the results of our systematic analysis reveal larger fingerprint-dependent changes in compound-associated SAR information than would have been anticipated.

  12. The large N-terminal region of the Brr2 RNA helicase guides productive spliceosome activation

    PubMed Central

    Absmeier, Eva; Wollenhaupt, Jan; Mozaffari-Jovin, Sina; Becke, Christian; Lee, Chung-Tien; Preussner, Marco; Heyd, Florian; Urlaub, Henning; Lührmann, Reinhard; Santos, Karine F.; Wahl, Markus C.

    2015-01-01

    The Brr2 helicase provides the key remodeling activity for spliceosome catalytic activation, during which it disrupts the U4/U6 di-snRNP (small nuclear RNA protein), and its activity has to be tightly regulated. Brr2 exhibits an unusual architecture, including an ∼500-residue N-terminal region, whose functions and molecular mechanisms are presently unknown, followed by a tandem array of structurally similar helicase units (cassettes), only the first of which is catalytically active. Here, we show by crystal structure analysis of full-length Brr2 in complex with a regulatory Jab1/MPN domain of the Prp8 protein and by cross-linking/mass spectrometry of isolated Brr2 that the Brr2 N-terminal region encompasses two folded domains and adjacent linear elements that clamp and interconnect the helicase cassettes. Stepwise N-terminal truncations led to yeast growth and splicing defects, reduced Brr2 association with U4/U6•U5 tri-snRNPs, and increased ATP-dependent disruption of the tri-snRNP, yielding U4/U6 di-snRNP and U5 snRNP. Trends in the RNA-binding, ATPase, and helicase activities of the Brr2 truncation variants are fully rationalized by the crystal structure, demonstrating that the N-terminal region autoinhibits Brr2 via substrate competition and conformational clamping. Our results reveal molecular mechanisms that prevent premature and unproductive tri-snRNP disruption and suggest novel principles of Brr2-dependent splicing regulation. PMID:26637280

  13. Morphotectonic evolution of passive margins undergoing active surface processes: large-scale experiments using numerical models.

    NASA Astrophysics Data System (ADS)

    Beucher, Romain; Huismans, Ritske S.

    2016-04-01

    Extension of the continental lithosphere can lead to the formation of a wide range of rifted margins styles with contrasting tectonic and geomorphological characteristics. It is now understood that many of these characteristics depend on the manner extension is distributed depending on (among others factors) rheology, structural inheritance, thermal structure and surface processes. The relative importance and the possible interactions of these controlling factors is still largely unknown. Here we investigate the feedbacks between tectonics and the transfers of material at the surface resulting from erosion, transport, and sedimentation. We use large-scale (1200 x 600 km) and high-resolution (~1km) numerical experiments coupling a 2D upper-mantle-scale thermo-mechanical model with a plan-form 2D surface processes model (SPM). We test the sensitivity of the coupled models to varying crust-lithosphere rheology and erosional efficiency ranging from no-erosion to very efficient erosion. We discuss how fast, when and how the topography of the continents evolves and how it can be compared to actual passive margins escarpment morphologies. We show that although tectonics is the main factor controlling the rift geometry, transfers of masses at the surface affect the timing of faulting and the initiation of sea-floor spreading. We discuss how such models may help to understand the evolution of high-elevated passive margins around the world.

  14. Large Scale Cortical Functional Networks Associated with Slow-Wave and Spindle-Burst-Related Spontaneous Activity

    PubMed Central

    McVea, David A.; Murphy, Timothy H.; Mohajerani, Majid H.

    2016-01-01

    Cortical sensory systems are active with rich patterns of activity during sleep and under light anesthesia. Remarkably, this activity shares many characteristics with those present when the awake brain responds to sensory stimuli. We review two specific forms of such activity: slow-wave activity (SWA) in the adult brain and spindle bursts in developing brain. SWA is composed of 0.5–4 Hz resting potential fluctuations. Although these fluctuations synchronize wide regions of cortex, recent large-scale imaging has shown spatial details of their distribution that reflect underlying cortical structural projections and networks. These networks are regulated, as prior awake experiences alter both the spatial and temporal features of SWA in subsequent sleep. Activity patterns of the immature brain, however, are very different from those of the adult. SWA is absent, and the dominant pattern is spindle bursts, intermittent high frequency oscillations superimposed on slower depolarizations within sensory cortices. These bursts are driven by intrinsic brain activity, which act to generate peripheral inputs, for example via limb twitches. They are present within developing sensory cortex before they are mature enough to exhibit directed movements and respond to external stimuli. Like in the adult, these patterns resemble those evoked by sensory stimulation when awake. It is suggested that spindle-burst activity is generated purposefully by the developing nervous system as a proxy for true external stimuli. While the sleep-related functions of both slow-wave and spindle-burst activity may not be entirely clear, they reflect robust regulated phenomena which can engage select wide-spread cortical circuits. These circuits are similar to those activated during sensory processing and volitional events. We highlight these two patterns of brain activity because both are prominent and well-studied forms of spontaneous activity that will yield valuable insights into brain function in

  15. Raman imaging with a fiber-coupled multichannel spectrograph.

    PubMed

    Schmälzlin, Elmar; Moralejo, Benito; Rutowska, Monika; Monreal-Ibero, Ana; Sandin, Christer; Tarcea, Nicolae; Popp, Jürgen; Roth, Martin M

    2014-11-20

    Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 × 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure.

  16. Use of a fiber optic probe for organic species determination

    DOEpatents

    Ekechukwu, Amy A.

    1996-01-01

    A fiber optic probe for remotely detecting the presence and concentration organic species in aqueous solutions. The probe includes a cylindrical housing with an organic species indicator, preferably diaminonaphthyl sulfonic acid adsorbed in a silica gel (DANS-modified gel), contained in the probe's distal end. The probe admits aqueous solutions to the probe interior for mixing within the DANS-modified gel. An optical fiber transmits light through the DANS-modified gel while the indicator reacts with organic species present in the solution, thereby shifting the location of the fluorescent peak. The altered light is reflected to a receiving fiber that carries the light to a spectrophotometer or other analysis device.

  17. A fiber optic temperature sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Jensen, Stephen C.; Tilstra, Shelle D.; Barnabo, Geoffrey A.; Thomas, David C.; Phillips, Richard W.

    1991-02-01

    A fiber-optic temperature sensor has been developed for aerospace applications on the basis of the time rate of decay (TRD) principle, with a view to an operational temperature range of -60 to 350 C. This TRD system has completed qualification testing and will then undergo flight tests. Attention is presently given to the design and performance of four low temperature sensors that are subelements of the larger sensor system; in order to convert analog signals into over/under temperature indications, simple comparators are implemented in software.

  18. Yellow light generation by frequency doubling of a fiber oscillator

    NASA Astrophysics Data System (ADS)

    Bacher, Christoph; Oliveira, Ricardo; Nogueira, Rogério N.; Romano, Valerio; Ryser, Manuel

    2016-04-01

    Laser sources with light-emission in the yellow spectral range around 577nm are very favorable for a variety of applications. These include applications in astronomy, in ophthalmology or in quantum optics. The generation and amplification of 1154 nm light is not straight forward when using Yb-doped optical fibers, since lasing occurs preferentially around the gain-maximum of 1030 nm. We generate the radiation within a fiber Bragg grating (FBG) based cavity and focused on reducing the amplified spontaneous emission (ASE). After the cavity, the output is frequency doubled to 577nm by using a second harmonic crystal.

  19. Epigenetic upregulation of large-conductance Ca2+-activated K+ channel expression in uterine vascular adaptation to pregnancy.

    PubMed

    Chen, Man; Dasgupta, Chiranjib; Xiong, Fuxia; Zhang, Lubo

    2014-09-01

    Our previous study demonstrated that pregnancy increased large-conductance Ca(2+)-activated potassium channel β1 subunit (BKβ1) expression and large-conductance Ca(2+)-activated potassium channel activity in uterine arteries, which were abrogated by chronic hypoxia. The present study tested the hypothesis that promoter methylation/demethylation is a key mechanism in epigenetic reprogramming of BKβ1 expression patterns in uterine arteries. Ovine BKβ1 promoter of 2315 bp spanning from -2211 to +104 of the transcription start site was cloned, and an Sp1-380 binding site that contains CpG dinucleotide in its core binding sequences was identified. Site-directed deletion of the Sp1 site significantly decreased the BKβ1 promoter activity. Estrogen receptor-α bound to the Sp1 site through tethering to Sp1 and upregulated the expression of BKβ1. The Sp1 binding site at BKβ1 promoter was highly methylated in uterine arteries of nonpregnant sheep, and methylation inhibited transcription factor binding and BKβ1 promoter activity. Pregnancy caused a significant decrease in CpG methylation at the Sp1 binding site and increased Sp1 binding to the BKβ1 promoter and BKβ1 mRNA abundance. Chronic hypoxia during gestation abrogated this pregnancy-induced demethylation and upregulation of BKβ1 expression. The results provide evidence of a novel mechanism of promoter demethylation in pregnancy-induced reprogramming of large-conductance Ca(2+)-activated potassium channel expression and function in uterine arteries and suggest new insights of epigenetic mechanisms linking gestational hypoxia to aberrant uteroplacental circulation and increased risk of preeclampsia.

  20. Differences in the social patterning of active travel between urban and rural populations: findings from a large UK household survey.

    PubMed

    Hutchinson, Jayne; White, Piran C L; Graham, Hilary

    2014-12-01

    To determine the social patterning of active travel of short journeys for urban and rural residents in a large UK representative sample. Associations between frequently walking or cycling short journeys and socio-demographic factors in the UK Household Longitudinal Study were determined using logistic regression. Urban residents were 64 % more likely to frequently engage in active travel than rural residents (95 % CI 1.52, 1.77). Being younger, male, without full-time employment and having a lower income independently predicted greater active travel for both urban and rural residents. Degree level education and not having children were independent predictors for urban, but not rural residents. Actively travelling short journeys is less common and independently associated with fewer socio-demographic factors in rural than in urban populations.

  1. Protein kinase activity associated with the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10).

    PubMed Central

    Chung, T D; Wymer, J P; Smith, C C; Kulka, M; Aurelian, L

    1989-01-01

    The large subunit of the herpes simplex virus type 2 (HSV-2) ribonucleotide reductase (RR1) is demonstrated to possess serine/threonine-specific kinase activity. Computer-assisted sequence analysis identified regions within the amino terminus of ICP10 that are homologous to the catalytic domain of known protein kinases (PKs). An in vitro kinase assay confirmed the ability of ICP10, immunoprecipitated from either HSV-2-infected cells or from cells transfected with an ICP10 expression vector, to autophosphorylate and transphosphorylate exogenous substrates in the presence of ATP and Mg2+. The HSV-1 RR1 was shown to be negative for PK activity under these conditions. PK activity was localized to a 57-kDa amino-terminal region within ICP10 that lacked RR activity. Images PMID:2545912

  2. Distribution of serum paraoxon hydrolyzing activity in a large Spanish population using a routine automized method in clinical laboratory.

    PubMed

    Carrera, V; Llopis, I; Sastre, J; Sogorb, M A; Vilanova, E

    2003-01-01

    This work was performed to adapt the manual laboratory method of measuring serum paraoxonase activity using a routine automatized method in the clinical laboratory and to study the distribution of paraoxonase activity in a large population from Alcoy, a region of Spain. The serum samples for the study were obtained from extractions of blood from 2891 individuals, distributed by sex and age groups, in a routine check in a primary care facility of Alcoy. Paraoxonase activity was assayed by measuring the release of p-nitrophenol according to a previously published method adapted to an automatized analyzer. The mean paraoxonase activity recorder was 70.2 +/- 16.5 IU/L. Paraoxonase activity in children (both males and females) was significantly lower (p < 0.0005) than in older individuals. Paraoxonase activity detected in males and females older than 56 was slightly lower than that detected in younger individuals, although in this case the difference was not statistically significant. The paraoxonase activity shows higher mean values in females than in males (p < 0.0005). Human paraoxonase activity shows a unimodal distribution pattern in the studied population, which is in contrast with other studies showing bimodal distribution.

  3. Temporal niche switching in Arabian oryx (Oryx leucoryx): Seasonal plasticity of 24h activity patterns in a large desert mammal.

    PubMed

    Davimes, Joshua G; Alagaili, Abdulaziz N; Bertelsen, Mads F; Mohammed, Osama B; Hemingway, Jason; Bennett, Nigel C; Manger, Paul R; Gravett, Nadine

    2017-08-01

    The Arabian oryx, a moderately large mammal that inhabits a harsh desert environment, has been shown to exhibit seasonal variations in activity and inactivity patterns. Here we analyzed the continuous year-round activity patterns of twelve free-roaming Arabian oryx under natural conditions from two varying desert environments in Saudi Arabia using abdominally implanted activity meters. We simultaneously recorded weather parameters at both sites to determine whether environmental factors are responsible for temporal niche switching as well as the seasonal structuring and timing of this behavioural plasticity. Our results demonstrate that Arabian oryx undergo temporal niche switching of 24h activity patterns at a seasonal level and exhibit distinct nocturnal/crepuscular activity during summer, diurnal activity during winter and intermittent patterns of behaviour during the transitional seasons of autumn and spring. In addition, the oryx exhibited inter- and intra-seasonal variations in the temporal budgeting of 24h activity patterns. Strong relationships with both photoperiod and ambient temperatures were found and in some instances suggested that increasing ambient temperatures are a primary driving force behind seasonal shifts in activity patterns. These adaptive patterns may be dictated by the availability of food and water, which in turn are strongly influenced by seasonal climate variations. Overall, the adaptive responses of free-roaming Arabian oryx in such harsh and non-laboratorial conditions provide a framework for comparing wild populations as well as aiding conservation efforts. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Active region 11748: Recurring X-class flares, large scale dimmings and waves.

    NASA Astrophysics Data System (ADS)

    Davey, Alisdair R.; Malanushenko, Anna; McIntosh, Scott W.

    2014-06-01

    AR 11748 was a relatively compact active region that crossed the solar disk between 05/14/2013 and 05/26/2013. Despite its size it produced a number X-class flares, and global scale eruptive events that were captured by the SDO Feature Finding Team's (FFT) Dimming Region Detector. Using the results of this module and other FFT modules, we present an analysis of the this AR region and investigate why it was so globally impactful.

  5. Large effects from small exposures. I. Mechanisms for endocrine-disrupting chemicals with estrogenic activity.

    PubMed Central

    Welshons, Wade V; Thayer, Kristina A; Judy, Barbara M; Taylor, Julia A; Curran, Edward M; vom Saal, Frederick S

    2003-01-01

    Information concerning the fundamental mechanisms of action of both natural and environmental hormones, combined with information concerning endogenous hormone concentrations, reveals how endocrine-disrupting chemicals with estrogenic activity (EEDCs) can be active at concentrations far below those currently being tested in toxicological studies. Using only very high doses in toxicological studies of EEDCs thus can dramatically underestimate bioactivity. Specifically: a) The hormonal action mechanisms and the physiology of delivery of EEDCs predict with accuracy the low-dose ranges of biological activity, which have been missed by traditional toxicological testing. b) Toxicology assumes that it is valid to extrapolate linearly from high doses over a very wide dose range to predict responses at doses within the physiological range of receptor occupancy for an EEDC; however, because receptor-mediated responses saturate, this assumption is invalid. c) Furthermore, receptor-mediated responses can first increase and then decrease as dose increases, contradicting the assumption that dose-response relationships are monotonic. d) Exogenous estrogens modulate a system that is physiologically active and thus is already above threshold, contradicting the traditional toxicological assumption of thresholds for endocrine responses to EEDCs. These four fundamental issues are problematic for risk assessment methods used by regulatory agencies, because they challenge the traditional use of extrapolation from high-dose testing to predict responses at the much lower environmentally relevant doses. These doses are within the range of current exposures to numerous chemicals in wildlife and humans. These problems are exacerbated by the fact that the type of positive and negative controls appropriate to the study of endocrine responses are not part of traditional toxicological testing and are frequently omitted, or when present, have been misinterpreted. PMID:12826473

  6. The architecture of the active surface control system of the Large Millimeter Telescope

    NASA Astrophysics Data System (ADS)

    Souccar, Kamal; Wallace, Gary; Grosslein, Ron; Schloerb, F. Peter

    2014-07-01

    One of the fundamental design principles of the LMT is that its segmented primary surface must be active: the position and orientation of each of the segments must be moved in order to maintain the precise parabolic surface that is required by the specifications. Consequently, a system of actuators, one at the corner of each segment, is used to move the segments to counteract surface deformations attributed to gravity or thermal effects. A new control system was designed and built within the project to implement an active surface at the LMT. The technical concept for the active surface control system is to provide a set of bus boxes with built-in control and I/O capabilities to run four actuators each. Bus boxes read the LVDT sensor position and limit switch status for each actuator and use this information to drive the actuator's DC motor, closing the position loop. Each bus box contains a DC power supply for the electronics, a second DC power supply for the motors, an embedded controller with I/O to close the position loop, and a custom printed circuit board to condition the LVDT signals and drive the motors. An interface printed circuit board resides in each actuator providing a single connector access to the LVDT, the motor, and the limit switches. During the fall of 2013, 84 bus boxes were commissioned to control the 336 actuators of the inner three rings of the telescope. The surface correction model was determined using holography measurements and the active surface system has been in regular use during the scientific observation at the LMT.

  7. High speed large viewing angle shutters for triple-flash active glasses

    NASA Astrophysics Data System (ADS)

    Caillaud, B.; Bellini, B.; de Bougrenet de la Tocnaye, J.-L.

    2009-02-01

    We present a new generation of liquid crystal shutters for active glasses, well suited to 3-D cinema current trends, involving triple flash regimes. Our technology uses a composite smectic C* liquid crystal mixture1. In this paper we focus on the electro-optical characterization of composite smectic-based shutters, and compare their performance with nematic ones, demonstrating their advantages for the new generation of 3-D cinema and more generally 3-D HDTV.

  8. Using Large Group Displays to Support Intensive Team Activities in C2

    DTIC Science & Technology

    2011-06-01

    Organization (DSTO) Edinburgh, PO Box 1500, Edinburgh SA 511 Australia (*) E-mail: : Point of contact information Denis.Gouin@drdc...Experiment (JEFX) 2004 exercises at Nellis Air Operations Center ( Darling & Means, 2005). This work echoes many of the considerations and challenges of...they use. For example, the DataWall evaluations ( Darling & Means, 2005) highlighted the need to use the displays to: “provide activity awareness to

  9. Space Active Optics: toward optimized correcting mirrors for future large spaceborne observatories

    NASA Astrophysics Data System (ADS)

    Laslandes, Marie; Hugot, Emmanuel; Ferrari, Marc; Lemaitre, Gérard; Liotard, Arnaud

    2011-10-01

    Wave-front correction in optical instruments is often needed, either to compensate Optical Path Differences, off-axis aberrations or mirrors deformations. Active optics techniques are developed to allow efficient corrections with deformable mirrors. In this paper, we will present the conception of particular deformation systems which could be used in space telescopes and instruments in order to improve their performances while allowing relaxing specifications on the global system stability. A first section will be dedicated to the design and performance analysis of an active mirror specifically designed to compensate for aberrations that might appear in future 3m-class space telescopes, due to lightweight primary mirrors, thermal variations or weightless conditions. A second section will be dedicated to a brand new design of active mirror, able to compensate for given combinations of aberrations with a single actuator. If the aberrations to be corrected in an instrument and their evolutions are known in advance, an optimal system geometry can be determined thanks to the elasticity theory and Finite Element Analysis.

  10. Large scale screening of commonly used Iranian traditional medicinal plants against urease activity

    PubMed Central

    2012-01-01

    Background and purpose of the study H. pylori infection is an important etiologic impetus usually leading to gastric disease and urease enzyme is the most crucial role is to protect the bacteria in the acidic environment of the stomach. Then urease inhibitors would increase sensitivity of the bacteria in acidic medium. Methods 137 Iranian traditional medicinal plants were examined against Jack bean urease activity by Berthelot reaction. Each herb was extracted using 50% aqueous methanol. The more effective extracts were further tested and their IC50 values were determined. Results 37 plants out of the 137 crude extracts revealed strong urease inhibitory activity (more than 70% inhibition against urease activity at 10 mg/ml concentration). Nine of the whole studied plants crude extracts were found as the most effective with IC50 values less than 500 μg/ml including; Rheum ribes, Sambucus ebulus, Pistachia lentiscus, Myrtus communis, Areca catechu, Citrus aurantifolia, Myristica fragrans, Cinnamomum zeylanicum and Nicotiana tabacum. Conclusions The most potent urease inhibitory was observed for Sambucus ebulus and Rheum ribes extracts with IC50 values of 57 and 92 μg/ml, respectively. PMID:23351780

  11. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, Silke; Walter, Thomas R.

    2009-06-01

    The study of volcanic triggering and interaction with the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of clustered eruptions and earthquakes may imply that interaction is important in some subregions. However, the subregions likely to suffer such clusters have not been systematically identified, and the processes responsible for the observed interaction remain unclear. We first review previous works about the clustered occurrence of eruptions and earthquakes, and describe selected events. We further elaborate available databases and confirm a statistically significant relationship between volcanic eruptions and earthquakes on the global scale. Moreover, our study implies that closed volcanic systems in particular tend to be activated in association with a tectonic earthquake trigger. We then perform a statistical study at the subregional level, showing that certain subregions are especially predisposed to concurrent eruption-earthquake sequences, whereas such clustering is statistically less significant in other subregions. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. The activity at volcanoes located in the predisposed subregions (e.g., Japan, Indonesia, Melanesia), however, often unexpectedly changes in association with either an imminent or a past earthquake.

  12. Distribution and activity of ammonia oxidizing bacteria in a large full-scale trickling filter.

    PubMed

    Persson, Frank; Wik, Torsten; Sörensson, Fred; Hermansso, Malte

    2002-03-01

    The biofilm in a full-scale nitrifying trickling filter (NTF) treating municipal wastewater has been investigated with microbiological methods using fluorescence in situ hybridization (FISH) with 16S rRNA oligonucleotide probes in combination with confocal laser scanning microscopy (CLSM) and mathematical modeling using a dynamic multi-species biofilm reactor model. Ammonia oxidizing bacteria (AOB) were found to belong to the genus Nitrosomonas at different depths in the NTF at every sampling occasion, corresponding to different long-term operational conditions for the NTF. Both the measurements and the corresponding simulated predictions showed the same general trend of a decrease with filter depth of the amount of biofilm, the proportion of AOB to all bacteria and the total amount of AOB. The latter decreased by several times from top to bottom of the NTF. Measurements and simulations of potential ammonium oxidizing activity in the biofilm also showed a decreasing activity with depth in the NTF, which generally was operating at close to complete nitrification. However, no difference was observed when the activity was normalized to the amount of biofilm, despite decreasing proportions of AOB to all bacteria with depth in the NTF. This could be explained by diffusion limitations in the biofilm from the upper parts of the NTF according to the biofilm reactor model. The relatively good agreement between the simulations and the measurements shows that the kind of biofilm reactor model used can qualitatively describe an averaged behavior and averaged composition of the biofilm in the reactor.

  13. Magnetic neutral lines of the large-scale magnetic field and solar activity

    SciTech Connect

    Makarov, V.I.; Tavastsherna, K.S.; Sivaraman, K.R.

    1986-06-01

    Two components in the size distribution of structures of the large-scale magnetic field are distinguished on the basis of H-alpha synoptic maps for the period 1955-1981. It is shown that the overall solar magnetic field has a latitudinal zonal structure, which is formed from elements of the first and second distributions. The boundaries of the latitude zones of the magnetic field oscillate about the mean latitudes or have only polar drift. Three types of quasiperiodic oscillations are noted, the periods of which differ in the S and N hemispheres. The most probable period of the oscillations (about 20 solar revolutions) is distinguished in the Southern Hemisphere. 14 references.

  14. A peptide with potent antifungal and antiproliferative activities from Nepalese large red beans.

    PubMed

    Ma, D Z; Wang, H X; Ng, T B

    2009-12-01

    An antifungal defensin-like peptide with a molecular mass of 7.1kDa was isolated from dried Nepalese large red beans (Phaseolus angularis). The purification protocol employed included ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The antifungal peptide was unadsorbed on DEAE-cellulose, and adsorbed on Affi-gel blue gel and SP-Sepharose. The antifungal peptide inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola with an IC(50) value of 1.4 and 1.8 microM, respectively. It did not inhibit HIV-1 reverse transcriptase when tested up to 200 microM. It exerted an antiproliferative action on L1210 leukemia cells and MBL2 lymphoma cells with an IC(50) of 15 and 60 microM, respectively.

  15. Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Lang, K. R.

    1986-01-01

    The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field.

  16. Experimental results of active control on a large structure to suppress vibration

    NASA Technical Reports Server (NTRS)

    Dunn, H. J.

    1991-01-01

    Three design methods, Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR), H-infinity, and mu-synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. Time histories of the measured motion are presented, and modal damping obtained during the experiments are compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed.

  17. Large loop conformation sampling using the activation relaxation technique, ART-nouveau method.

    PubMed

    St-Pierre, Jean-François; Mousseau, Normand

    2012-07-01

    We present an adaptation of the ART-nouveau energy surface sampling method to the problem of loop structure prediction. This method, previously used to study protein folding pathways and peptide aggregation, is well suited to the problem of sampling the conformation space of large loops by targeting probable folding pathways instead of sampling exhaustively that space. The number of sampled conformations needed by ART nouveau to find the global energy minimum for a loop was found to scale linearly with the sequence length of the loop for loops between 8 and about 20 amino acids. Considering the linear scaling dependence of the computation cost on the loop sequence length for sampling new conformations, we estimate the total computational cost of sampling larger loops to scale quadratically compared to the exponential scaling of exhaustive search methods.

  18. Checkpoint inhibitor is active against large cell neuroendocrine carcinoma with high tumor mutation burden.

    PubMed

    Wang, Victoria E; Urisman, Anatoly; Albacker, Lee; Ali, Siraj; Miller, Vincent; Aggarwal, Rahul; Jablons, David

    2017-09-19

    Large cell neuroendocrine tumor (LCNEC) of the lung is a rare and aggressive tumor similar to small cell lung cancer (SCLC). Thus, it is often treated similarly to SCLC in the front-line setting with a platinum doublet. However, treatment for patients beyond the first line remains undefined. We report the case of a patient with stage IB LCNEC (PD-L1 negative but positive for PD-L1 amplification and tumor mutation burden high) who progressed after adjuvant chemotherapy after surgery and subsequent therapy with an antibody drug conjugate targeting a neuroendocrine-specific cell surface marker but achieved a significant and durable response with pembrolizumab, a humanized IgG4 monoclonal anti-PD-1 antibody. Immunotherapy with checkpoint inhibitors is an effective treatment option for patients with metastatic LCNEC, even if PD-L1 expression is negative.

  19. Oxygen-Activated Growth and Bandgap Tunability of Large Single-Crystal Bilayer Graphene

    NASA Astrophysics Data System (ADS)

    Hao, Yufeng; Hone, James; Ruoff, Rodney; Colombo, Luigi; the Hone Group Team

    Distinct from zero-bandgap single-layer graphene, Bernal-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. In this presentation, we will focus on the most recent progress in the identification of new growth mechanisms towards large-area single-layer BLG on Copper: multiple control experiments and first-principles calculations are used to support the proposed mechanisms. We emphasize that trace amount of impurities on metal surface are critical to initiate graphene growth and affect the growth kinetics. Furthermore, contrary to the traditional viewpoint that graphene growth is always surface-limited process, our new observations strongly suggest that metal bulk plays a role to feed carbon species for graphene growth. State-of-the-art structural characterizations and electrical transport measurements of the CVD graphene layers will be presented as well.

  20. Large-scale, dynamic transformations in fuel moisture drive wildfire activity across southeastern Australia

    NASA Astrophysics Data System (ADS)

    Nolan, R. H.; Boer, M. M.; Resco de Dios, V.; Caccamo, G.; Bradstock, R. A.

    2016-05-01

    The occurrence of large, high-intensity wildfires requires plant biomass, or fuel, that is sufficiently dry to burn. This poses the question, what is "sufficiently dry"? Until recently, the ability to address this question has been constrained by the spatiotemporal scale of available methods to monitor the moisture contents of both dead and live fuels. Here we take advantage of recent developments in macroscale monitoring of fuel moisture through a combination of remote sensing and climatic modeling. We show there are clear thresholds of fuel moisture content associated with the occurrence of wildfires in forests and woodlands. Furthermore, we show that transformations in fuel moisture conditions across these thresholds can occur rapidly, within a month. Both the approach presented here, and our findings, can be immediately applied and may greatly improve fire risk assessments in forests and woodlands globally.

  1. Corrector design with active vase mirrors that allows a fixed telescope to access a large region of the sky

    NASA Astrophysics Data System (ADS)

    Moretto, Gilberto; Borra, Ermanno F.

    1997-04-01

    We investigate whether a three-mirror system, having secondary and the tertiary mirrors with surfaces warped by Zernike polynomials generated by active vase mirrors, is suitable to do the corrections of a fixed parabolic mirror observing at large angles from the zenith. We obtain designs of correctors with remarkable images and control of the distortion of the field of the view contained within a field greater than 15 Deg.

  2. NeuroCa: integrated framework for systematic analysis of spatiotemporal neuronal activity patterns from large-scale optical recording data

    PubMed Central

    Jang, Min Jee; Nam, Yoonkey

    2015-01-01

    Abstract. Optical recording facilitates monitoring the activity of a large neural network at the cellular scale, but the analysis and interpretation of the collected data remain challenging. Here, we present a MATLAB-based toolbox, named NeuroCa, for the automated processing and quantitative analysis of large-scale calcium imaging data. Our tool includes several computational algorithms to extract the calcium spike trains of individual neurons from the calcium imaging data in an automatic fashion. Two algorithms were developed to decompose the imaging data into the activity of individual cells and subsequently detect calcium spikes from each neuronal signal. Applying our method to dense networks in dissociated cultures, we were able to obtain the calcium spike trains of ∼1000 neurons in a few minutes. Further analyses using these data permitted the quantification of neuronal responses to chemical stimuli as well as functional mapping of spatiotemporal patterns in neuronal firing within the spontaneous, synchronous activity of a large network. These results demonstrate that our method not only automates time-consuming, labor-intensive tasks in the analysis of neural data obtained using optical recording techniques but also provides a systematic way to visualize and quantify the collective dynamics of a network in terms of its cellular elements. PMID:26229973

  3. A fiber Bragg grating sensor system for estimating the large deflection of a lightweight flexible beam

    NASA Astrophysics Data System (ADS)

    Peng, Te; Yang, Yangyang; Ma, Lina; Yang, Huayong

    2016-10-01

    A sensor system based on fiber Bragg grating (FBG) is presented which is to estimate the deflection of a lightweight flexible beam, including the tip position and the tip rotation angle. In this paper, the classical problem of the deflection of a lightweight flexible beam of linear elastic material is analysed. We present the differential equation governing the behavior of a physical system and show that this equation although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. We used epoxy glue to attach the FBG sensors to specific locations upper and lower surface of the beam in order to measure local strain measurements. A quasi-distributed FBG static strain sensor network is designed and established. The estimation results from FBG sensors are also compared to reference displacements from the ANSYS simulation results and the experimental results obtained in the laboratory in the static case. The errors of the estimation by FBG sensors are analysed for further error-correction and option-design. When the load weight is 20g, the precision is the highest, the position errors ex and ex are 0.19%, 0.14% respectively, the rotation error eθ, is 1.23%.

  4. Large scale study on measurement of respiration activity (AT(4)) by Sapromat and OxiTop.

    PubMed

    Binner, Erwin; Böhm, Katharina; Lechner, Peter

    2012-10-01

    In the run-up for amending the Austrian landfill ordinance, parameters were developed to assess the stability/reactivity of mechanically-biologically pretreated residual wastes. The Landfill Ordinance 2008 regulates limit values for Respiration Activity (="Atmungsaktivität") RA(4) (AT(4))<7mgO(2)*(g dry matter (DM))(-1), Gas Generation Sum GS(21)<20Nl*kgDM(-1) and alternatively Gas Evolution (="Gasbildung") GB(21)<20Nl*kgDM(-1). Methods for analysing these parameters were established by the Austrian Standards Institute (2004). As laboratory practice shows, these methods also are used for the assessment of other wastes (sewage sludge, commercial waste, material from abandoned sites, biowaste compost). For measurement of respiration activity in Austria mainly two methods are used: the Sapromat®-method and the OxiTop®-method. Whether respectively to what extent these two methods give same results, is discussed in this paper. Since 2009 at ABF-BOKU 169 respiration activity tests of samples taken from different stages of MBT - as well as biowaste composting processes, materials from landfills as well as abandoned sites and residues from anaerobic treatment plants were analysed parallel by Sapromat® and OxiTop®. The results manifest very strong correlation between the Sapromat® and OxiTop® method. The correlation coefficient is 0.993. As a very clear tendency OxiTop® gives lower amounts than Sapromat®. In average the lower values of OxiTop® are around 88%. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Walter, T. R.

    2009-04-01

    The study of volcanic triggering and coupling to the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of volcano-earthquake interactions in, e.g., Europe and Japan, may imply that clustered occurrence is important in some regions. However, the regions likely to suffer clustered eruption-earthquake activity have not been systematically identified, and the processes responsible for the observed interaction are debated. We first review previous works about the correlation of volcanic eruptions and earthquakes, and describe selected local clustered events. Following an overview of previous statistical studies, we further elaborate the databases of correlated eruptions and earthquakes from a global perspective. Since we can confirm a relationship between volcanic eruptions and earthquakes on the global scale, we then perform a statistical study on the regional level, showing that time and distance between events follow a linear relationship. In the time before an earthquake, a period of volcanic silence often occurs, whereas in the time after, an increase in volcanic activity is evident. Our statistical tests imply that certain regions are especially predisposed to concurrent eruption-earthquake pairs, e.g., Japan, whereas such pairing is statistically less significant in other regions, such as Europe. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. Volcanoes located in the predisposed regions (e.g., Japan, Indonesia, Melanesia), however, indeed often have unexpectedly changed in association with either an imminent or a past earthquake.

  6. A large family of anti‐activators accompanying XylS/AraC family regulatory proteins

    PubMed Central

    Yan, Michael B.; Tran, Minh; Wright, Nathan; Luzader, Deborah H.; Kendall, Melissa M.; Ruiz‐Perez, Fernando; Nataro, James P.

    2016-01-01

    Summary AraC Negative Regulators (ANR) suppress virulence genes by directly down‐regulating AraC/XylS members in Gram‐negative bacteria. In this study, we sought to investigate the distribution and molecular mechanisms of regulatory function for ANRs among different bacterial pathogens. We identified more than 200 ANRs distributed in diverse clinically important gram negative pathogens, including Vibrio spp., Salmonella spp., Shigella spp., Yersinia spp., Citrobacter spp., enterotoxigenic (ETEC) and enteroaggregative E. coli (EAEC), and members of the Pasteurellaceae. By employing a bacterial two hybrid system, pull down assays and surface plasmon resonance (SPR) analysis, we demonstrate that Aar (AggR‐activated regulator), a prototype member of the ANR family in EAEC, binds with high affinity to the central linker domain of AraC‐like member AggR. ANR‐AggR binding disrupted AggR dimerization and prevented AggR‐DNA binding. ANR homologs of Vibrio cholerae, Citrobacter rodentium, Salmonella enterica and ETEC were capable of complementing Aar activity by repressing aggR expression in EAEC strain 042. ANR homologs of ETEC and Vibrio cholerae bound to AggR as well as to other members of the AraC family, including Rns and ToxT. The predicted proteins of all ANR members exhibit three highly conserved predicted α‐helices. Site‐directed mutagenesis studies suggest that at least predicted α‐helices 2 and 3 are required for Aar activity. In sum, our data strongly suggest that members of the novel ANR family act by directly binding to their cognate AraC partners. PMID:27038276

  7. A large family of anti-activators accompanying XylS/AraC family regulatory proteins.

    PubMed

    Santiago, Araceli E; Yan, Michael B; Tran, Minh; Wright, Nathan; Luzader, Deborah H; Kendall, Melissa M; Ruiz-Perez, Fernando; Nataro, James P

    2016-07-01

    AraC Negative Regulators (ANR) suppress virulence genes by directly down-regulating AraC/XylS members in Gram-negative bacteria. In this study, we sought to investigate the distribution and molecular mechanisms of regulatory function for ANRs among different bacterial pathogens. We identified more than 200 ANRs distributed in diverse clinically important gram negative pathogens, including Vibrio spp., Salmonella spp., Shigella spp., Yersinia spp., Citrobacter spp., enterotoxigenic (ETEC) and enteroaggregative E. coli (EAEC), and members of the Pasteurellaceae. By employing a bacterial two hybrid system, pull down assays and surface plasmon resonance (SPR) analysis, we demonstrate that Aar (AggR-activated regulator), a prototype member of the ANR family in EAEC, binds with high affinity to the central linker domain of AraC-like member AggR. ANR-AggR binding disrupted AggR dimerization and prevented AggR-DNA binding. ANR homologs of Vibrio cholerae, Citrobacter rodentium, Salmonella enterica and ETEC were capable of complementing Aar activity by repressing aggR expression in EAEC strain 042. ANR homologs of ETEC and Vibrio cholerae bound to AggR as well as to other members of the AraC family, including Rns and ToxT. The predicted proteins of all ANR members exhibit three highly conserved predicted α-helices. Site-directed mutagenesis studies suggest that at least predicted α-helices 2 and 3 are required for Aar activity. In sum, our data strongly suggest that members of the novel ANR family act by directly binding to their cognate AraC partners.

  8. Large-Scale Controls on Atlantic Tropical Cyclone Activity on Seasonal Time Scale

    NASA Technical Reports Server (NTRS)

    Lim, Young-Kwon; Schubert, Siegfried D.; Reale, Oreste; Molod, Andrea M.; Suarez, Max J.; Auer, Benjamin M.

    2016-01-01

    Interannual variations in seasonal tropical cyclone (TC) activity (e.g., genesis frequency and location, track pattern, and landfall) over the Atlantic are explored by employing observationally-constrained simulations with the NASA Goddard Earth Observing System version (GEOS-5) atmospheric general circulation model. The climate modes investigated are El Nino-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and the Atlantic Meridional Mode (AMM). The results show that the NAO and AMM can strongly modify and even oppose the well- known ENSO impacts, like in 2005, when a strong positive AMM (associated with warm SSTs and a negative SLP anomaly over the western tropical Atlantic), led to a very active TC season with enhanced TC genesis over the Caribbean Sea and a number of landfalls over North America, under a neutral ENSO condition. On the other end, the weak TC activity during 2013 (characterized by weak negative Nio index) appears caused by a NAO-induced positive SLP anomaly with enhanced vertical wind shear over the tropical North Atlantic. During 2010, the combined impact of the three modes produced positive SST anomalies across the entire low-latitudinal Atlantic and a weaker subtropical high, leading to more early recurvers and thus fewer landfalls despite enhanced TC genesis. The study provides evidence that TC number and track are very sensitive to the relative phases and intensities of these three modes, and not just to ENSO alone. Examination of seasonal predictability reveals that predictive skill of the three modes is limited over tropics to sub-tropics, with the AMM having the highest predictability over the North Atlantic, followed by ENSO and NAO.

  9. Synthesis, characterization and catalytic activity of novel large network polystyrene-immobilized organic bases

    DOE PAGES

    Tassi, Marco; Bartollini, Elena; Adriaensens, Peter; ...

    2015-12-07

    In view of searching for efficient polymeric supports for organic bases to be used in environmentally friendly reaction conditions, novel gel-type cross-linked polystyrenes functionalized with diethylamine and 1,5,7-triazabicyclo[4.4.0]dec-5-ene, have been prepared. Moreover, the structural properties and morphology of these catalysts have been determined by extensive solid state NMR experiments, FTIR spectroscopy and SEM/TEM microscopy. SPACeR-supported bases were found to exhibit high catalytic activity in the epoxide ring opening by phenols. Finally, a range of β-substituted alcohols have been readily and regioselectively synthesized.

  10. Conformable, flexible, large-area networks of pressure and thermal sensors with organic transistor active matrixes

    NASA Astrophysics Data System (ADS)

    Someya, Takao; Kato, Yusaku; Sekitani, Tsuyoshi; Iba, Shingo; Noguchi, Yoshiaki; Murase, Yousuke; Kawaguchi, Hiroshi; Sakurai, Takayasu

    2005-08-01

    Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots, enabling them to operate in unstructured environments. Recently developed large-area pressure sensors made with organic transistors have been proposed for electronic artificial skin (E-skin) applications. These sensors are bendable down to a 2-mm radius, a size that is sufficiently small for the fabrication of human-sized robot fingers. Natural human skin, however, is far more complex than the transistor-based imitations demonstrated so far. It performs other functions, including thermal sensing. Furthermore, without conformability, the application of E-skin on three-dimensional surfaces is impossible. In this work, we have successfully developed conformable, flexible, large-area networks of thermal and pressure sensors based on an organic semiconductor. A plastic film with organic transistor-based electronic circuits is processed to form a net-shaped structure, which allows the E-skin films to be extended by 25%. The net-shaped pressure sensor matrix was attached to the surface of an egg, and pressure images were successfully obtained in this configuration. Then, a similar network of thermal sensors was developed with organic semiconductors. Next, the possible implementation of both pressure and thermal sensors on the surfaces is presented, and, by means of laminated sensor networks, the distributions of pressure and temperature are simultaneously obtained. Author contributions: T. Someya designed research; T. Someya, Y.K., T. Sekitani, S.I., Y.N., Y.M., H.K., and T. Sakurai performed research; and T. Someya wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Freely available online through the PNAS open access option.Abbreviations: E-skin, electronic artificial skin; IDS, source-drain current; PTCDI, 3,4,9,10-perylene-tetracarboxylic-diimide; parylene, polychloro-para-xylylene; CuPc, copper

  11. The challenge of "teaching" large groups of learners: strategies to increase active participation and learning.

    PubMed

    Nierenberg, D W

    1998-01-01

    While teaching in a tutorial, seminar, or problem-based learning group format may be the most fun and most active/interactive for both learner and faculty mentor, there are situations in medical student education in which various constraints require the use of the "lecture" format. Similar constraints may occur in the field of continuing medical education, or graduate medical education, as well. When this occurs, the faculty mentor can increase the active participation of the learners in the audience by continuously stressing seven key pedagogical (androgogical) principles. These include: 1) begin the learning exercise with a clinical example or anecdote to show the relevance of the material to the student; 2) frequently ask the students whether they have ever seen examples of what you describe in their previous experience with patients, personal experience, experience with relatives, etc.; 3) ask students frequently whether they have heard similar material presented differently in other courses; 4) recruit students to help solve "mystery cases"; 5) show examples of similar material from real life (e.g., patient descriptions, or even excerpts from favorite TV shows); 6) ask students to help summarize key points at the end of the session; and 7) allow, or even encourage, whispering during the class. Using some or all of these techniques can help turn a "lecture format" into a much more fun, interactive, and valuable session that emphasizes "learning" rather than "teaching."

  12. Simultaneous SMM flat crystal spectrometer and Very Large Array observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Lang, Kenneth R.; Willson, Robert F.; Smith, Kermit L.; Strong, Keith T.

    1987-01-01

    High-resolution images of the quiescent emission from two solar active regions at 20 cm (VLA) and soft X-ray (SMM FCS) wavelengths are compared. There are regions where the X-ray coronal loops have been completely imaged at 20 cm wavelength. In other regions, the X-ray radiation was detected without detectable 20 cm radiation, and vice versa. The X-ray data were used to infer average electron temperatures of about 3-million K and average electron densities of about 2.5 x 10 to the 9th/cu cm for the X-ray emitting plasma in the two active regions. The thermal bremsstrahlung of the X-ray emitting plasma is optically thin at 20 cm wavelength. The 20 cm brightness temperatures were always less than T(e), which is consistent with optically thin bremsstrahlung. The low T(B) can be explained if a higher, cooler plasma covers the hotter X-ray emitting plasma. Thermal gyroresonance radiation must account for the intense 20 cm radiation near and above sunspots where no X-ray radiation is detected.

  13. A Helioseismic Survey to Investigate Relationships between Subsurface Flows beneath Large Active Regions and Solar Flares

    NASA Astrophysics Data System (ADS)

    Braun, Douglas; Leka, K D.; Barnes, Graham

    2014-06-01

    A survey of the subsurface flow properties of about 120 of the largest active regions, determined from the application of helioseismic holography to Dopplergrams obtained with the HMI instrument onboard the Solar Dynamics Observatory, is being carried out. The overriding goal is to characterize differences in the subsurface flows between active regions associated with eruptive flares and the flows observed in relatively quiescent regions. Applications to flare forecasting comprise only one part of this investigation, since the potential response of the subsurface environment to eruptive events during and after their occurrence is also of scientific interest. Other priorities include understanding the limitations of the helioseismic methods, identifying and correcting systematic effects, and validating the reliability of the measurements using artificial data. While inversions to determine the variation with depth of subsurface flows are planned, preliminary results will be discussed which make use of proxies for near-surface depth-integrated properties, including the horizontal component of the flow divergence and the vertical component of the flow vorticity.This work is supported by the Solar Terrestrial Program of the National Science Foundation, through grant AGS-1127327, and by the National Oceanic and Atmospheric Administration SBIR program.

  14. A large difference in the progenitor masses of active and passive galaxies in the EAGLE simulation

    NASA Astrophysics Data System (ADS)

    Clauwens, Bart; Franx, Marijn; Schaye, Joop

    2016-11-01

    Cumulative number density matching of galaxies is a method to observationally connect descendent galaxies to their typical main progenitors at higher redshifts and thereby to assess the evolution of galaxy properties. The accuracy of this method is limited due to galaxy merging and scatter in the stellar mass growth history of individual galaxies. Behroozi et al. have introduced a refinement of the method, based on abundance matching of observed galaxies to the Bolshoi dark matter-only simulation. The EAGLE cosmological hydrosimulation is well suited to test this method, because it reproduces the observed evolution of the galaxy stellar mass function and the passive fraction. We find agreement with the Behroozi et al. method for the complete sample of main progenitors of z = 0 galaxies, but we also find a strong dependence on the current star formation rate. Passive galaxies with a stellar mass up to 1010.75 M⊙ have a completely different median mass history than active galaxies of the same mass. This difference persists if we only select central galaxies. This means that the cumulative number density method should be applied separately to active and passive galaxies. Even then, the typical main progenitor of a z = 0 galaxy already spans two orders of magnitude in stellar mass at z = 2.

  15. APE: the Active Phasing Experiment to test new control system and phasing technology for a European Extremely Large Optical Telescope

    NASA Astrophysics Data System (ADS)

    Gonte, F.; Yaitskova, N.; Derie, F.; Constanza, A.; Brast, R.; Buzzoni, B.; Delabre, B.; Dierickx, P.; Dupuy, C.; Esteves, R.; Frank, C.; Guisard, S.; Karban, R.; Koenig, E.; Kolb, J.; Nylund, M.; Noethe, L.; Surdej, I.; Courteville, A.; Wilhelm, R.; Montoya, L.; Reyes, M.; Esposito, S.; Pinna, E.; Dohlen, K.; Ferrari, M.; Langlois, M.

    2005-08-01

    The future European Extremely Large Telescope will be composed of one or two giant segmented mirrors (up to 100 m of diameter) and of several large monolithic mirrors (up to 8 m in diameter). To limit the aberrations due to misalignments and defective surface quality it is necessary to have a proper active optics system. This active optics system must include a phasing system to limit the degradation of the PSF due to misphasing of the segmented mirrors. We will present the lastest design and development of the Active Phasing Experiment that will be tested in laboratory and on-sky connected to a VLT at Paranal in Chile. It includes an active segmented mirror, a static piston plate to simulate a secondary segmented mirror and of four phasing wavefront sensors to measure the piston, tip and tilt of the segments and the aberrations of the VLT. The four phasing sensors are the Diffraction Image Phase Sensing Instrument developed by Instituto de Astrofisica de Canarias, the Pyramid Phasing Sensor developed by Arcetri Astrophysical Observatory, the Shack-Hartmann Phasing Sensor developed by the European Southern Observatory and the Zernike Unit for Segment phasing developed by Laboratoire d'Astrophysique de Marseille. A reference measurement of the segmented mirror is made by an internal metrology developed by Fogale Nanotech. The control system of Active Phasing Experiment will perform the phasing of the segments, the guiding of the VLT and the active optics of the VLT. These activities are included in the Framework Programme 6 of the European Union.

  16. Observation of the activity of selected Oort Cloud comets with perihelia at large distances from the Sun

    NASA Astrophysics Data System (ADS)

    Kulyk, Iryna; Rousselot, Philippe; Korsun, Pavlo

    2016-10-01

    Many comets exhibit considerable level of activity at large distances from the Sun, where sublimation of crystalline water ice cannot account for observable comae. Different patterns of physical activity already observed at large heliocentric distances may be related to the primordial differences in the composition of comet nuclei. Therefore, monitoring of physical activity in the wide range of heliocentric distances can potentially contribute to understanding of internal structure of comet-like bodies. We have observed ten long periodic comets with orbital perihelia lying beyond the "water ice sublimation zone" to quantify the level of physical activity in the wide range of heliocentric distances. Pre-perihelion observations were made when targets moved between 16.7 and 6.5 au from the Sun; post perihelion activity was monitored between 5.2 and 10.6 au. The bulk of the data were gathered with the 2-m Robotic Liverpool Telescope (Observatorio del Roque de Los Muchachos, La Palma, Spain). Some targets were observed with the 2-m RC Telescope located at Peak Terskol Observatory and the 6-m Telescope of the Special Astrophysical Observatory (Northern Caucasus, Russia). Since most of recently obtained spectra of distant active objects are continuum dominated, we use B, V, R images to estimate dust production rates, an upper limit on nucleus radii, and color indices of near nucleus region. The comets C/2005 L3 (McNaught) and C/2006 S3 (Boattini), which exhibit the considerable level of activity, have been repeatedly observed. This enables us to infer the heliocentric dependence of dust production rates, perihelion brightness asymmetries, and color variations over the comae caused possibly by small changes in dust particle properties.

  17. Molecular Information of charybdotoxin blockade in the large conductance calcium-activated potassium channel.

    PubMed

    Qiu, Su; Yi, Hong; Liu, Hui; Cao, Zhijian; Wu, Yingliang; Li, Wenxin

    2009-07-01

    The scorpion toxin, charybdotoxin (ChTX), is the first identified peptide inhibitor for the large-conductance Ca2+ and voltage-dependent K+ (BK) channel, and the chemical information of the interaction between ChTX and BK channel remains unclear today. Using combined computational methods, we obtained a ChTX-BK complex structure model, which correlated well with the mutagenesis data. In this complex, ChTX mainly used its beta-sheet domains to associate the BK channel with a conserved pore-blocking Lys27. Another crucial Tyr36 residue of ChTX lied over the loop connecting selectivity filter and S6 helix of BK channel, forming a hydrogen bond with Gly291 of BK channel. Besides, the unique turret region of BK channel was found to be far away from bound ChTX, which could explain the fact that many BK channel blockers show less selectivity over Kv channels. Together, all these information is helpful to reveal the diverse interactions between scorpion toxins and potassium channels and can accelerate the molecular engineering of specific inhibitor design.

  18. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    NASA Astrophysics Data System (ADS)

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  19. Acute lymphoblastic leukaemia cells produce large extracellular vesicles containing organelles and an active cytoskeleton

    PubMed Central

    Johnson, Suzanne M.; Dempsey, Clare; Parker, Catriona; Mironov, Aleksandr; Bradley, Helen; Saha, Vaskar

    2017-01-01

    ABSTRACT Extracellular vesicles have been described in non-paracrine cellular interactions in cancer. We report a similar phenomenon in B-cell precursor (BCP) acute lymphoblastic leukaemia (ALL). Using advanced microscopy and high throughput screening, we further characterise a subset of large vesicles (LEVs) identified in cell lines, murine models of human BCP-ALL and clinical samples. Primary ALL blasts and cell lines released heterogeneous anucleate vesicles <6 micron into extracellular fluids. Larger LEVs were enclosed in continuous membranes, contained intact organelles and demonstrated an organised cytoskeleton. An excess of circulating CD19-positive LEVs were observed in diagnostic samples and isolated from mice engrafted with BCP-ALL primary cells. LEVs exhibited dynamic shape change in vitro and were internalised by other leukaemic cell lines leading to phenotypic transformation analogous to the cell of origin. In patient-derived xenografts, LEVs were released by primary ALL cells into extracellular spaces and internalised by murine mesenchymal cells in vivo. Collectively these data highlight the heterogeneity but accessibility of LEVs in clinical samples and their potential to provide a unique insight into the biology of the cell of origin and to their development as novel biomarkers to aid diagnosis and improve therapeutic outcomes. PMID:28386390

  20. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    PubMed Central

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-01-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications. PMID:24619247

  1. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer.

    PubMed

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-12

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  2. Neurotransmitter measurement with a fiber optic probe using pulsed ultraviolet resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Schulze, H. Georg; Greek, L. Shane; Blades, Michael W.; Bree, Alan V.; Gorzalka, Boris B.; Turner, Robin F. B.

    1997-05-01

    Many techniques have been developed to investigate the chemistry associated with brain activity. These techniques generally fall into two categories: fast techniques with species restricted sensitivity and slow techniques with generally unrestricted species sensitivity. Therefore, a need exists for a fast non-invasive technique sensitive to a wide array of biologically relevant compounds in order to measure chemical brain events in real time. The work presented here describes the progress made toward the development of a novel neurotransmitter probe. A fiber-optic linked Raman and tunable ultraviolet resonance Raman system was assembled with custom designed optical fiber probes. Probes of several different geometries were constructed and their working curves obtained in aqueous mixtures of methyl orange and potassium nitrate to determine the best probe configuration given particular sample characteristics. Using this system, the ultraviolet resonance Raman spectra of some neurotransmitters were measured with a fiber-optic probe and are reported here for the first time. The probe has also been used to measure neurotransmitter secretions obtained from depolarized rat pheochromocytoma cells.

  3. Phase-B activities for the Large Isotope Spectrometer for Astromag

    NASA Technical Reports Server (NTRS)

    Mewaldt, Richard A.; Stone, E. C.

    1995-01-01

    The scientific objectives of the LISA experiment are to (1) extend measurements of the isotopic composition of cosmic ray elements from Be to Ni (Z = 4 to 28) into the energy range beyond 1 GeV per nucleon; (2) to measure the energy spectra of heavy elements up to energies greater than 100 GeV/nucleon with good statistical accuracy; and (3) to search for heavy anti-matter with Z greater than 2 in cosmic rays. This grant focussed on defining the Cherenkov subsystem of the LISA experiment. The Phase-B efforts included the following activities: (1) definition of the LISA Cherenkov counters for the Space Station version of Astromag; (2) testing of the 5-inch fine mesh photomultipliers; (3) development of the aerogel radiator; and (4) study of a free-flyer version of Astromag.

  4. Enhancing Cognitive Abilities with Comprehensive Training: A Large, Online, Randomized, Active-Controlled Trial

    PubMed Central

    Hardy, Joseph L.; Nelson, Rolf A.; Thomason, Moriah E.; Sternberg, Daniel A.; Katovich, Kiefer; Farzin, Faraz; Scanlon, Michael

    2015-01-01

    Background A variety of studies have demonstrated gains in cognitive ability following cognitive training interventions. However, other studies have not shown such gains, and questions remain regarding the efficacy of specific cognitive training interventions. Cognitive training research often involves programs made up of just one or a few exercises, targeting limited and specific cognitive endpoints. In addition, cognitive training studies typically involve small samples that may be insufficient for reliable measurement of change. Other studies have utilized training periods that were too short to generate reliable gains in cognitive performance. Methods The present study evaluated an online cognitive training program comprised of 49 exercises targeting a variety of cognitive capacities. The cognitive training program was compared to an active control condition in which participants completed crossword puzzles. All participants were recruited, trained, and tested online (N = 4,715 fully evaluable participants). Participants in both groups were instructed to complete one approximately 15-minute session at least 5 days per week for 10 weeks. Results Participants randomly assigned to the treatment group improved significantly more on the primary outcome measure, an aggregate measure of neuropsychological performance, than did the active control group (Cohen’s d effect size = 0.255; 95% confidence interval = [0.198, 0.312]). Treatment participants showed greater improvements than controls on speed of processing, short-term memory, working memory, problem solving, and fluid reasoning assessments. Participants in the treatment group also showed greater improvements on self-reported measures of cognitive functioning, particularly on those items related to concentration compared to the control group (Cohen’s d = 0.249; 95% confidence interval = [0.191, 0.306]). Conclusion Taken together, these results indicate that a varied training program composed of a number of

  5. Large-scale performance and design for construction activity erosion control best management practices.

    PubMed

    Faucette, L B; Scholl, B; Beighley, R E; Governo, J

    2009-01-01

    The National Pollutant Discharge Elimination System (NPDES) Phase II requires construction activities to have erosion and sediment control best management practices (BMPs) designed and installed for site storm water management. Although BMPs are specified on storm water pollution prevention plans (SWPPPs) as part of the construction general permit (GP), there is little evidence in the research literature as to how BMPs perform or should be designed. The objectives of this study were to: (i) comparatively evaluate the performance of common construction activity erosion control BMPs under a standardized test method, (ii) evaluate the performance of compost erosion control blanket thickness, (iii) evaluate the performance of compost erosion control blankets (CECBs) on a variety of slope angles, and (iv) determine Universal Soil Loss Equation (USLE) cover management factors (C factors) for these BMPs to assist site designers and engineers. Twenty-three erosion control BMPs were evaluated using American Society of Testing and Materials (ASTM) D-6459, standard test method for determination of ECB performance in protecting hill slopes from rainfall induced erosion, on 4:1 (H:V), 3:1, and 2:1 slopes. Soil loss reduction for treatments exposed to 5 cm of rainfall on a 2:1 slope ranged from-7 to 99%. For rainfall exposure of 10 cm, treatment soil loss reduction ranged from 8 to 99%. The 2.5 and 5 cm CECBs significantly reduced erosion on slopes up to 2:1, while CECBs < 2.5 cm are not recommended on slopes >or= 4:1 when rainfall totals reach 5 cm. Based on the soil loss results, USLE C factors ranged from 0.01 to 0.9. These performance and design criteria should aid site planners and designers in decision-making processes.

  6. Activation of large form galanin-LI by extracellular processing in small cell lung carcinoma tissue.

    PubMed

    Yamamoto, Hiroyuki; Iguchi, Kazuaki; Ohno, Satoshi; Yokogawa, Takashi; Nishikawa, Kazuya; Hoshino, Minoru

    2011-10-01

    Galanin is a neuropeptide that is widely distributed in the central and peripheral nervous systems. Some small cell lung carcinoma (SCLC) cell lines such as SBC-3A release only the high-molecular-mass form, with lower molecular mass forms being undetectable. To investigate the mechanism of processing of progalanin to active peptide, we studied galanin-LI in both the culture media of SBC-3A cells and in extracts from in vivo mouse SBC-3A tumors. SBC-3A cells were found to release high molecular mass galanin, but did not release active peptides. In contrast, tumor extract contained both high-molecular-mass galanin, and a cleaved lower-molecular-mass form of the peptide (8, 5 and 2 kDa). The lower-molecular-mass peptide was identified as galanin(1-20) by MALDI-TOF mass spectrometry. We then looked at MMP-2 and MMP-9 release from SBC-3A cells and tumor tissue treated with galanin and progalanin, as revealed by gelatin zymography. Galanin elicited pro-MMP-2 and pro-MMP-9 release from SBC-3A cells and tumor tissue; however, recombinant progalanin induced pro-MMP-2 and pro-MMP-9 release from tumor tissue only. This study has shown that the galanin-LI released from SCLC SBC-3A cells consisted of the high-molecular-mass peptide form, and was processed extracellularly to galanin(1-20). Furthermore, galanin was seen to induce pro-MMP-2 and pro-MMP-9 release from SBC-3A cells.

  7. Choosing between small, likely rewards and large, unlikely rewards activates inferior and orbital prefrontal cortex.

    PubMed

    Rogers, R D; Owen, A M; Middleton, H C; Williams, E J; Pickard, J D; Sahakian, B J; Robbins, T W

    1999-10-15

    Patients sustaining lesions of the orbital prefrontal cortex (PFC) exhibit marked impairments in the performance of laboratory-based gambling, or risk-taking, tasks, suggesting that this part of the human PFC contributes to decision-making cognition. However, to date, little is known about the particular regions of the orbital cortex that participate in this function. In the present study, eight healthy volunteers were scanned, using H(2)(15)0 PET technology, while performing a novel computerized risk-taking task. The task involved predicting which of two mutually exclusive outcomes would occur, but critically, the larger reward (and penalty) was associated with choice of the least likely outcome, whereas the smallest reward (and penalty) was associated with choice of the most likely outcome. Resolving these "conflicting" decisions was associated with three distinct foci of regional cerebral blood flow increase within the right inferior and orbital PFC: laterally, in the anterior part of the middle frontal gyrus [Brodmann area 10 (BA 10)], medially, in the orbital gyrus (BA 11), and posteriorly, in the anterior portion of the inferior frontal gyrus (BA 47). By contrast, increases in the degree of conflict inherent in these decisions was associated with only limited changes in activity within orbital PFC and the anterior cingulate cortex. These results suggest that decision making recruits neural activity from multiple regions of the inferior PFC that receive information from a diverse set of cortical and limbic inputs, and that the contribution of the orbitofrontal regions may involve processing changes in reward-related information.

  8. Enhancing Cognitive Abilities with Comprehensive Training: A Large, Online, Randomized, Active-Controlled Trial.

    PubMed

    Hardy, Joseph L; Nelson, Rolf A; Thomason, Moriah E; Sternberg, Daniel A; Katovich, Kiefer; Farzin, Faraz; Scanlon, Michael

    2015-01-01

    A variety of studies have demonstrated gains in cognitive ability following cognitive training interventions. However, other studies have not shown such gains, and questions remain regarding the efficacy of specific cognitive training interventions. Cognitive training research often involves programs made up of just one or a few exercises, targeting limited and specific cognitive endpoints. In addition, cognitive training studies typically involve small samples that may be insufficient for reliable measurement of change. Other studies have utilized training periods that were too short to generate reliable gains in cognitive performance. The present study evaluated an online cognitive training program comprised of 49 exercises targeting a variety of cognitive capacities. The cognitive training program was compared to an active control condition in which participants completed crossword puzzles. All participants were recruited, trained, and tested online (N = 4,715 fully evaluable participants). Participants in both groups were instructed to complete one approximately 15-minute session at least 5 days per week for 10 weeks. Participants randomly assigned to the treatment group improved significantly more on the primary outcome measure, an aggregate measure of neuropsychological performance, than did the active control group (Cohen's d effect size = 0.255; 95% confidence interval = [0.198, 0.312]). Treatment participants showed greater improvements than controls on speed of processing, short-term memory, working memory, problem solving, and fluid reasoning assessments. Participants in the treatment group also showed greater improvements on self-reported measures of cognitive functioning, particularly on those items related to concentration compared to the control group (Cohen's d = 0.249; 95% confidence interval = [0.191, 0.306]). Taken together, these results indicate that a varied training program composed of a number of tasks targeted to different cognitive

  9. Did volcanic activity of the Emeishan large igneous province expand in Wuchiapingian times?

    NASA Astrophysics Data System (ADS)

    Bagherpour, Borhan; Bucher, Hugo; Yuan, Dong-Xun; Shen, Shu-zhong; Leu, Marc; Zhang, Chao

    2017-04-01

    Emplacement of the Emeishan Large Igneous Province (ELIP) in the Capitanian (Middle Permian) is associated with several environmental changes (e.g. facies change, carbon cycle perturbation and temperature rise) across the Guadalupian-Lopingian (G-L) interval in South China. However, most of the reported changes are within the Capitanian stage or close to the G-L boundary. Here, we report an episode of drastic environmental changes from the Pingtang syncline (S. Guizhou) that is similar with the previously known ones but which is significantly younger. The studied section represents a protracted and stepwise facies change from a benthos rich, thick-bedded and light grey shallow water limestone (Unit A) to a 30 m-thick unit with thin-bedded dark (OM-rich) radiolarian-spiculitic facies (Unit B). The latter is overlain by an 8 m-thick unit of volcaniclastic sandstone and silts defining a succession of decimetric, cyclic and thinning upward layers (Unit C). The base of the overlying medium-bedded limestone unit (Unit D) contain radiolarian and sponge spicules whose abundance progressively decrease up section with a progressive replacement by abundant benthic faunas concomitant with the transition to thick bedded limestone. A total of five conodont index species (assigned to Clarkina) of early Wuchiapingian age were recognized from Unit A and Unit B. The observed facies transition from Unit A to Unit B indicates a drastic drowning event. Unit C represents a distal turbiditic succession and the overlying Unit D shows an upward shallowing trend back to the initial shallow marine condition. Compilation of sedimentary records across G-L in South China reveals that such drowning events tend to cluster within three discrete time intervals. The drowning events may or may not end with deposition of either volcanics or volcaniclastics. Two first clusters display drowning events overlain by ELIP volcanic rocks or volcaniclastics of ELIP origin and are of Capitanian age. Only the

  10. Active large sector collapse and architectural evolution of the Pico Island (Azores)

    NASA Astrophysics Data System (ADS)

    Marques, F. O.; Hildenbrand, A.; Catalao Fernandes, J.; Catita, C. M.; Costa, A. C.; Sibrant, A.

    2011-12-01

    Volcanic ocean islands are particularly prone to flank instability. Episodes of flank destabilization can remove great amounts of volcanic material, either as creeping rotational landslides along a deep detachment, or in the form of fast running debris avalanches produced by the sudden flank rupture. Based on high-resolution DEM, fieldwork, GPS, InSAR and geochronological data, we put in evidence ongoing collapse of the southeast flank of the Pico volcanic Ridge (Azores) and its architectural evolution. OUR Data show that: (1) the collapsing sector is several cubic kilometres in dimension; (2) the collapse structure involves several curved scarps with a geometry and kinematics typical of normal faults; (3) the central part of the collapse is experiencing little horizontal displacement toward the sea (< 3 mm/yr) but significant downward movement (7-12 mm/yr); (4) motion of the island flank is not accommodated by a low-angle deep basal detachment such as observed elsewhere on typical slumps; (5) the outer part of Pico SE flank is experiencing faster subsidence than the inner parts, which likely reflects recent individualization of a steep seaward-dipping fault in the distal part of the moving mass; (6) evolution of the deformation along this accident could involve the sudden detachment of a large distal block, possibly followed by the gradual destabilization of the whole collapse area. Such scenario would have hazardous consequences for the local population and could trigger a major tsunami, which may impact the surrounding coastal environments and cause considerable damage; (7) the architectural evolution of the island has been made by short periods of volcanic construction, followed by longer periods of destruction by mass wasting episodes like the one here described.

  11. Linking anti-predator behaviour to prey demography reveals limited risk effects of an actively hunting large carnivore

    USGS Publications Warehouse

    Middleton, Arthur D.; Kauffman, Matthew J.; McWhirter, Douglas E.; Jimenez, Michael D.; Cook, Rachel C.; Cook, John G.; Albeke, Shannon E.; Sawyer, Hall; White, P.J.

    2013-01-01

    Ecological theory predicts that the diffuse risk cues generated by wide-ranging, active predators should induce prey behavioural responses but not major, population- or community-level consequences. We evaluated the non-consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and pregnancy of elk (Cervus elaphus), their primary prey in the Greater Yellowstone Ecosystem. When wolves approached within 1 km, elk increased their rates of movement, displacement and vigilance. Even in high-risk areas, however, these encounters occurred only once every 9 days. Ultimately, despite 20-fold variation in the frequency of encounters between wolves and individual elk, the risk of predation was not associated with elk body fat or pregnancy. Our findings suggest that the ecological consequences of actively hunting large carnivores, such as the wolf, are more likely transmitted by consumptive effects on prey survival than NCEs on prey behaviour.

  12. Linking anti-predator behaviour to prey demography reveals limited risk effects of an actively hunting large carnivore.

    PubMed

    Middleton, Arthur D; Kauffman, Matthew J; McWhirter, Douglas E; Jimenez, Michael D; Cook, Rachel C; Cook, John G; Albeke, Shannon E; Sawyer, Hall; White, P J

    2013-08-01

    Ecological theory predicts that the diffuse risk cues generated by wide-ranging, active predators should induce prey behavioural responses but not major, population- or community-level consequences. We evaluated the non-consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and pregnancy of elk (Cervus elaphus), their primary prey in the Greater Yellowstone Ecosystem. When wolves approached within 1 km, elk increased their rates of movement, displacement and vigilance. Even in high-risk areas, however, these encounters occurred only once every 9 days. Ultimately, despite 20-fold variation in the frequency of encounters between wolves and individual elk, the risk of predation was not associated with elk body fat or pregnancy. Our findings suggest that the ecological consequences of actively hunting large carnivores, such as the wolf, are more likely transmitted by consumptive effects on prey survival than NCEs on prey behaviour.

  13. Large-scale investigation of the role of trait activation theory for understanding assessment center convergent and discriminant validity.

    PubMed

    Lievens, Filip; Chasteen, Christopher S; Day, Eric Anthony; Christiansen, Neil D

    2006-03-01

    This study used trait activation theory as a theoretical framework to conduct a large-scale test of the interactionist explanation of the convergent and discriminant validity findings obtained in assessment centers. Trait activation theory specifies the conditions in which cross-situationally consistent and inconsistent candidate performances are likely to occur. Results obtained by aggregating correlations across 30 multitrait-multimethod matrices supported the propositions of trait activation theory, shedding a more positive light on the construct validity puzzle in assessment centers. Overall, convergence among assessment center ratings was better between exercises that provided an opportunity to observe behavior related to the same trait, and discrimination among ratings within exercises was generally better for dimensions that were not expressions of the same underlying traits. Implications for assessment center research and practice are discussed.

  14. Quantitative high-throughput screening: A titration-based approach that efficiently identifies biological activities in large chemical libraries

    PubMed Central

    Inglese, James; Auld, Douglas S.; Jadhav, Ajit; Johnson, Ronald L.; Simeonov, Anton; Yasgar, Adam; Zheng, Wei; Austin, Christopher P.

    2006-01-01

    High-throughput screening (HTS) of chemical compounds to identify modulators of molecular targets is a mainstay of pharmaceutical development. Increasingly, HTS is being used to identify chemical probes of gene, pathway, and cell functions, with the ultimate goal of comprehensively delineating relationships between chemical structures and biological activities. Achieving this goal will require methodologies that efficiently generate pharmacological data from the primary screen and reliably profile the range of biological activities associated with large chemical libraries. Traditional HTS, which tests compounds at a single concentration, is not suited to this task, because HTS is burdened by frequent false positives and false negatives and requires extensive follow-up testing. We have developed a paradigm, quantitative HTS (qHTS), tested with the enzyme pyruvate kinase, to generate concentration–response curves for >60,000 compounds in a single experiment. We show that this method is precise, refractory to variations in sample preparation, and identifies compounds with a wide range of activities. Concentration–response curves were classified to rapidly identify pyruvate kinase activators and inhibitors with a variety of potencies and efficacies and elucidate structure–activity relationships directly from the primary screen. Comparison of qHTS with traditional single-concentration HTS revealed a high prevalence of false negatives in the single-point screen. This study demonstrates the feasibility of qHTS for accurately profiling every compound in large chemical libraries (>105 compounds). qHTS produces rich data sets that can be immediately mined for reliable biological activities, thereby providing a platform for chemical genomics and accelerating the identification of leads for drug discovery. PMID:16864780

  15. Were Holocene large slumps in Lake Geneva off the city of Lausanne caused by fault activity?

    NASA Astrophysics Data System (ADS)

    Correia Demand, Jehanne; Marillier, François; Kremer, Katrina; Girardclos, Stéphanie

    2014-05-01

    Lake Geneva is set in an area where glacier advances and retreats have carved Tertiary Molasse rocks in front of the Alpine units. Glacial and lacustrine sediments have accumulated in the lake on top of the Molasse. Within Holocene sedimentary layers, seismic studies in the central part of Lake Geneva ("Grand-Lac") have shown the presence of several mass transport deposits (MTD). A large one, MTD A, is observed off the city of Lausanne. The depth of the associated failure scars (100 m water depth), its volume (~ 0.13 km3), and the occurrence of other smaller MTDs that were possibly co-deposited with MTD A point to the occurrence of a major slide event in the lake, most likely associated with an earthquake. Based on 14C dating, the sediment age model for MTD A gives an age interval of 1865-1608 BC (Kremer et al. 2014). To resolve the details of the MTDs off Lausanne, and to better understand its geological context different seismic systems were used. These were a 3.5 KHz pinger with a theoretical vertical resolution of 0.15 m and a multichannel system with water-gun or air-gun seismic sources with vertical resolution of 0.6 m and 1.1 m, respectively. After a first pass processing, the multi-channel data were reprocessed in order to take into account the shape of the streamer in the water and to enhance the results of migration. In addition to typical seismic images of MTDs observed in other alpine lakes such as chaotic or transparent seismic character between well-organized reflections, two intriguing positive water-bottom topographic features associated with apparent sub-vertical offsets are revealed by the seismic data. They are located in the near vicinity of the depot centers of the MTDs and conspicuously located near faults in the Tertiary Molasse. These are thrust faults that are offset by small strike-slip faults, and we suggest that the positive topographic features are linked to a compressive component within the sediments due to displacements along these

  16. Measuring the Impact of Active Learning in a Redesigned Large-enrollment Introductory Geoscience Survey Course

    NASA Astrophysics Data System (ADS)

    Slater, T. F.; Slater, S. J.; Lyons, D. J.; Manhart, K.; Wehunt, M.; Kapp, J.; Richardson, R. M.

    2008-12-01

    Over the past two years, faculty in the UA Geosciences engaged in a major course redesign effort with the goal of improving student learning and attitudes while, at the same time, dramatically reducing costs of offering such a course. The course serves as an undergraduate general education science requirement. Using a reformed teaching framework of learner-centered education, the large-enrollment, introductory geosciences survey course was overhauled to include interactive lectures, just-in-time online quizzes, a next- generation textbook, and weekly discussions lead by graduate students and undergraduate peer mentors. The Geosciences Concept Inventory (GCI) was given as a pre-test/post-test to students in the pre-modified course and the reformed course to compare student learning in terms of gain scores. Although the entire 78-items were administered, divided into three forms, only the 36-items that most directly related to course content were used for analysis. Students in the unmodified course had a pre-test GCI percentage correct of 28.67 (SD=11.45, n=96) which increased to 45.26 (SD=11.76, n=84) on the post-test. After course redesign, students had a pre-test GCI percentage correct of 38.62 (SD=8.42, n=144) which increased a post-test GCI score of 48.73 (SD=7.49, n=132). Although the gains from pre-test to post-test are statistically significant, the different in post-test GCI scores between the two groups is not. This is interpreted as students' knowledge levels, insofar as the GCI can measure, were equivalent in both courses. The Likert-style Attitudes Toward Science Survey was given as an end-of-class post-test to students in the pre-modified course and as a pre-test post-test the reformed course to compare student attitudes between the courses. The average ranking on a 5-point scale as a pre-test was 3.454 (SD=1.259, n=508) whereas the post-tests for the unmodified course was 3.49 (SD=1.05, n=101) and 3.50 (SD=1.127, n=369) for the reformed course. As is

  17. A Large Sample of Magnetically-Active Stars Observed With Kepler

    NASA Astrophysics Data System (ADS)

    Wells, Mark; Neff, J. E.; Brown, A.; Ayres, T. R.; Basri, G. S.; Berdyugina, S.; Harper, G.; Hawley, S. L.; Korhonen, H.; Kowalski, A.; Micela, G.; Piskunov, N. E.; Ramsey, L. W.; Saar, S. H.; Walkowicz, L. M.

    2013-01-01

    We have observed about 325 stars in our Kepler Guest Observer programs (Cycles 1 through 4). For most of these targets, we are analyzing extremely high-precision light curves that have been continuously sampled every 30 minutes for up to 3 years. Our sample of candidate magnetically-active stars was selected primarily using GALEX colors. Starspots, pulsations, and variations due to eclipsing and contact binaries combine to produce a rich variety of light curves. We have developed semi-automated procedures to characterize this variability and thus to classify the targets and identify the physical mechanisms that dominate their Kepler light curves. We will describe these procedures and discuss the range of physical properties covered by our final classification scheme. We are using this Kepler database of variability over timescales of minutes to years to provide diagnostics of flares, starspot formation, evolution, migration, and ultimately of stellar cycles in general. This work contains results obtained using the NASA Kepler satellite and from the Apache Point Observatory, the MMT (using NOAO community access time), and the Hobby-Eberly Telescope. Funding is provided by NASA Kepler grants NNX10AC51G, NNX11AC79G, and NNX12AC85G to the University of Colorado, by NSF grant AST-1109695 to the College of Charleston, and by a grant from the South Carolina Space Grant consortium.

  18. Vagal control of cardiac electrical activity and wall motion during ventricular fibrillation in large animals.

    PubMed

    Naggar, Isaac; Nakase, Ko; Lazar, Jason; Salciccioli, Louis; Selesnick, Ivan; Stewart, Mark

    2014-07-01

    Vagal inputs control pacemaking and conduction systems in the heart. Anatomical evidence suggests a direct ventricular action, but functional evidence that separates direct and indirect (via the conduction system) vagal actions is less well established. We studied vagus nerve stimulation (VNS) during sinus rhythm and ventricular fibrillation (VF) in pigs and sheep to determine: 1) the range of unilateral and bilateral actions (inotropic and chronotropic) and 2) whether VNS alters left ventricular motion and/or electrical activity during VF, a model of abnormal electrical conduction of the left ventricle that excludes sinus and atrioventricular nodal function. Adult pigs (N=8) and sheep (N=10) were anesthetized with urethane and mechanically ventilated. VNS was performed in animals at 1, 2, 5, 10, 20, 50, and 100Hz for 20s. VF was induced with direct current to the ventricles or occlusion of the left anterior descending coronary artery. In 4 pigs and 3 sheep, left ventricular wall motion was assessed from endocardial excursion in epicardial echocardiography. In sheep and pigs, the best frequency among those tested for VNS during sinus rhythm to produce sustained electrical and mechanical ventricular standstill was 50Hz for unilateral or bilateral stimulation. When applied during VF, bilateral VNS increased the variability of the dominant VF frequency, indicating a direct impact on the excitability of ventricular myocytes, and decreased endocardial excursion by more than 50% during VF. We conclude that the vagus nerve directly modulates left ventricular function independently from its effects on the conduction system.

  19. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity

    PubMed Central

    ALANIS, Paul K. B.; YAMAYA, Yusuke; TAKEUCHI, Akihiro; SASAI, Yoichi; OKADA, Yoshihiro; NAGAO, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km × 3 km × 3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano’s activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions. PMID:24126286

  20. Flow and active mixing have a strong impact on bacterial growth dynamics in the proximal large intestine

    NASA Astrophysics Data System (ADS)

    Cremer, Jonas; Segota, Igor; Yang, Chih-Yu; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

    2016-11-01

    More than half of fecal dry weight is bacterial mass with bacterial densities reaching up to 1012 cells per gram. Mostly, these bacteria grow in the proximal large intestine where lateral flow along the intestine is strong: flow can in principal lead to a washout of bacteria from the proximal large intestine. Active mixing by contractions of the intestinal wall together with bacterial growth might counteract such a washout and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate contractions. We investigate growth along the channel under a steady nutrient inflow. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term. Based on this model, we discuss bacterial growth dynamics in the human large intestine using flow- and mixing-behavior having been observed for humans.

  1. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity.

    PubMed

    Alanis, Paul K B; Yamaya, Yusuke; Takeuchi, Akihiro; Sasai, Yoichi; Okada, Yoshihiro; Nagao, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km×3 km×3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano's activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions.

  2. Solar-terrestrial effect controls seismic activity to a large extent (Invited)

    NASA Astrophysics Data System (ADS)

    Duma, G.

    2010-12-01

    Several observational results and corresponding publications in the 20 century indicate that earthquakes in many regions happen systematically in dependence on the time of day and on the season as well. In the recent decade, studies on this topic have also been intensively performed at the Central Institute for Meteorology and Geodynamics (ZAMG), Vienna. Any natural effect on Earth which systematically appears at certain hours of the day or at a special season can solely be caused by a solar or lunar influence. And actually, statistic results on seismic activity reveal a correlation with the solar cycles. Examples of this seismic performance are shown. To gain more clarity about these effects, the three-hour magnetic index Kp, which characterizes the magnetic field disturbances, mainly caused by the solar particle radiation, the solar wind, was correlated with the seismic energy released by earthquakes over decades. Kp is determined from magnetic records of 13 observatories worldwide and continuously published by ISGI, France. It is demonstrated that a highly significant correlation between the geomagnetic index Kp and the annual seismic energy release in regions at latitudes between 35 and 60° N exists. Three regions of continental size were investigated, using the USGS (PDE) earthquake catalogue data. In the period 1974-2009 the Kp cycle periods range between 9 and 12 years, somewhat different to the sunspot number cycles of 11 years. Seismicity follows the Kp cycles with high coincidence. A detailed analysis of this correlation for N-America reveals, that the sum of released energy by earthquakes per year changes by a factor up to 100 with Kp. It is shown that during years of high Kp there happen e.g. 1 event M7, 4 events M6 and 30 events M5 per year, instead of only 10 events M5 in years with lowest Kp. Almost the same relation appears in other regions of continental size, with the same significance. The seismicity in S-America clearly follows the Kp cycles

  3. Large steric effect in the substitution reaction of amines with phosphoimidazolide-activated nucleosides

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Stronach, M. W.; Ketner, R. J.; Hurley, T. B.

    1995-01-01

    Aliphatic amines react with phosphoimidazolide-activated derivatives of guanosine and cytidine (ImpN) by replacing the imidazole group. The kinetics of reaction of guanosine 5'-phospho-2-methylimidazolide (2-MeImpG) with glycine ethyl ester, glycinamide, 2-methoxyethylamine, n-butylamine, morpholine, dimethylamine (Me2NH), ethylmethylamine (EtNHMe), diethylamine (Et2NH), pyrrolidine, and piperidine were determined in water at 37 degrees C. With primary amines, a plot of the logarithm of the rate constant for attack by the amine on the protonated substrate, log kSH(A), versus the pKa of the amine exhibits a good linear correlation with a Bronsted slope, beta nuc = 0.48. Most of the secondary amines tested react with slightly higher reactivity than primary amines of similar pKa. Interestingly, some secondary amines show substantially lower reactivity than might be expected: EtNHMe reacts about eight times, and Et2NH at least 100 times, more slowly than Me2NH although all three amines are of similar basicity. For comparison, the kinetics of reaction of guanosine 5'-phosphoimidazolide (ImpG) and cytidine 5'-phosphoimidazolide (ImpC) were determined with Me2NH, EtNHMe, and Et2NH, and similar results were obtained. These results establish that the increased steric hindrance observed with the successive addition of ethyl groups are not due to any special steric requirements imposed by the guanosine or the methyl on the 2-methylimidazole leaving group of 2-MeImpG. It is concluded that addition of ethyl and, perhaps, groups larger than ethyl dramatically increases the kinetic barrier for addition of aliphatic secondary amines to the P-N bond of ImpN. This study supports the observation that the primary amino groups on the natural polyamines are at least 2 orders of magnitude more reactive than the secondary amino groups in the reaction with ImpN.

  4. Magnetic Properties of Solar Active Regions That Govern Large Solar Flares and Eruptions

    NASA Astrophysics Data System (ADS)

    Toriumi, Shin; Schrijver, Carolus J.; Harra, Louise K.; Hudson, Hugh; Nagashima, Kaori

    2017-01-01

    Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim of understanding the magnetic properties that govern such flares and eruptions, we systematically survey all flare events with Geostationary Orbiting Environmental Satellite levels of ≥M5.0 within 45° from disk center between 2010 May and 2016 April. These criteria lead to a total of 51 flares from 29 ARs, for which we analyze the observational data obtained by the Solar Dynamics Observatory. More than 80% of the 29 ARs are found to exhibit δ-sunspots, and at least three ARs violate Hale’s polarity rule. The flare durations are approximately proportional to the distance between the two flare ribbons, to the total magnetic flux inside the ribbons, and to the ribbon area. From our study, one of the parameters that clearly determine whether a given flare event is CME-eruptive or not is the ribbon area normalized by the sunspot area, which may indicate that the structural relationship between the flaring region and the entire AR controls CME productivity. AR characterization shows that even X-class events do not require δ-sunspots or strong-field, high-gradient polarity inversion lines. An investigation of historical observational data suggests the possibility that the largest solar ARs, with magnetic flux of 2 × 1023 Mx, might be able to produce “superflares” with energies of the order of 1034 erg. The proportionality between the flare durations and magnetic energies is consistent with stellar flare observations, suggesting a common physical background for solar and stellar flares.

  5. The third catalog of active galactic nuclei detected by the Fermi large area telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Atwood, W. B.; ...

    2015-08-25

    We present the third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC). It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (more » $$| b| \\gt 10^\\circ $$), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. There were about 50% of the BL Lacs that had no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. Furthermore, the energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.« less

  6. Large-amplitude 5-HT1A receptor activation: a new mechanism of profound, central analgesia.

    PubMed

    Colpaert, F C; Tarayre, J P; Koek, W; Pauwels, P J; Bardin, L; Xu, X-J; Wiesenfeld-Hallin, Z; Cosi, C; Carilla-Durand, E; Assié, M B; Vacher, B

    2002-11-01

    We report the discovery of F 13640 and evidence suggesting this agent to produce powerful, broad-spectrum analgesia by novel molecular and neuroadaptative mechanisms. F 13640 stimulates G(alphaomicron) protein coupling to 5-HT(1A) receptors to an extent unprecedented by selective, non-native 5-HT(1A) ligands. Fifteen minutes after its injection in normal rats, F 13640 (0.01-2.5 mg/kg) decreases the vocalization threshold to paw pressure; 15 min upon injection in rats that are exposed to formalin-induced tonic nociception, F 13640 inhibits pain behavior. The initial hyperalgesia induced by 0.63 mg/kg F 13640 was followed, 8 hrs later, by paradoxical hypo-algesia; 5 mg/kg of morphine produces the opposite effects (i.e., hypo-algesia followed by hyper-algesia). Repeated F 13640 injections cause an increase in the basal vocalization threshold and a reduction of F 13640-produced hyperalgesia; in these conditions, morphine causes basal hyperalgesia and antinociceptive tolerance. Continuous two-week infusion of F 13640 (0.63 mg/day) exerts little effect on the threshold in normal rats, but markedly reduces analgesic self-administration in arthritic rats. F 13640 infusion also decreases allodynic responses to tactile and thermal stimulations in rats sustaining spinal cord or sciatic nerve injury. In these models of chronic nociceptive and neuropathic pain, the analgesia afforded by F 13640 consistently surpasses that of morphine (5 mg/day), imipramine (2.5 mg/day), ketamine (20 mg/day) and gabapentin (10 mg/day). Very-high-efficacy 5-HT(1A) receptor activation constitutes a novel mechanism of central analgesia that grows rather than decays with chronicity, that is amplified by nociceptive stimulation, and that may uniquely relieve persistent nociceptive and neuropathic pains.

  7. The third catalog of active galactic nuclei detected by the Fermi large area telescope

    SciTech Connect

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Gonzalez, J. Becerra; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Carpenter, B.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D’Abrusco, R.; D’Ammando, F.; Angelis, A. de; Desiante, R.; Digel, S. W.; Venere, L. Di; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Focke, W. B.; Franckowiak, A.; Fuhrmann, L.; Fukazawa, Y.; Furniss, A. K.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kataoka, J.; Kawano, T.; Krauss, F.; Kuss, M.; Mura, G. La; Larsson, S.; Latronico, L.; Leto, C.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Paggi, A.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Salvetti, D.; Schaal, M.; Schinzel, F. K.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Sokolovsky, K. V.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Winer, B. L.; Wood, K. S.; Zimmer, S.

    2015-08-25

    We present the third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC). It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes ($| b| \\gt 10^\\circ $), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. There were about 50% of the BL Lacs that had no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. Furthermore, the energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

  8. The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Becerra Gonzalez, J.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Carpenter, B.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Abrusco, R.; D'Ammando, F.; de Angelis, A.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Focke, W. B.; Franckowiak, A.; Fuhrmann, L.; Fukazawa, Y.; Furniss, A. K.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kataoka, J.; Kawano, T.; Krauss, F.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Leto, C.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Ojha, R.; Omodei, N.; Orienti, M.; Orlando, E.; Paggi, A.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romani, R. W.; Salvetti, D.; Schaal, M.; Schinzel, F. K.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Sokolovsky, K. V.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Winer, B. L.; Wood, K. S.; Zimmer, S.

    2015-09-01

    The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (| b| \\gt 10^\\circ ), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

  9. Inhibition of MALT1 protease activity is selectively toxic for activated B cell-like diffuse large B cell lymphoma cells.

    PubMed

    Ferch, Uta; Kloo, Bernhard; Gewies, Andreas; Pfänder, Vera; Düwel, Michael; Peschel, Christian; Krappmann, Daniel; Ruland, Jürgen

    2009-10-26

    Diffuse large B cell lymphoma (DLBCL) is the most common type of lymphoma in humans. The aggressive activated B cell-like (ABC) subtype of DLBCL is characterized by constitutive NF-kappaB activity and requires signals from CARD11, BCL10, and the paracaspase MALT1 for survival. CARD11, BCL10, and MALT1 are scaffold proteins that normally associate upon antigen receptor ligation. Signal-induced CARD11-BCL10-MALT1 (CBM) complexes couple upstream events to IkappaB kinase (IKK)/NF-kappaB activation. MALT1 also possesses a recently recognized proteolytic activity that cleaves and inactivates the negative NF-kappaB regulator A20 and BCL10 upon antigen receptor ligation. Yet, the relevance of MALT1 proteolytic activity for malignant cell growth is unknown. Here, we demonstrate preassembled CBM complexes and constitutive proteolysis of the two known MALT1 substrates in ABC-DLBCL, but not in germinal center B cell-like (GCB) DLBCL. ABC-DLBCL cell treatment with a MALT1 protease inhibitor blocks A20 and BCL10 cleavage, reduces NF-kappaB activity, and decreases the expression of NF-kappaB targets genes. Finally, MALT1 paracaspase inhibition results in death and growth retardation selectively in ABC-DLBCL cells. Thus, our results indicate a growth-promoting role for MALT1 paracaspase activity in ABC-DLBCL and suggest that a pharmacological MALT1 protease inhibition could be a promising approach for lymphoma treatment.

  10. Control of translational activation by PIM kinase in activated B-cell diffuse large B-cell lymphoma confers sensitivity to inhibition by PIM447

    PubMed Central

    Peters, Tara L.; Li, Lingxiao; Tula-Sanchez, Ana A.; Pongtornpipat, Praechompoo; Schatz, Jonathan H.

    2016-01-01

    The PIM family kinases promote growth and survival of tumor cells and are expressed in a wide variety of human cancers. Their potential as therapeutic targets, however, is complicated by overlapping activities with multiple other pathways and remains poorly defined in most clinical scenarios. Here we explore activity of the new pan-PIM inhibitor PIM447 in a variety of lymphoid-derived tumors. We find strong activity in cell lines derived from the activated B-cell subtype of diffuse large B-cell lymphoma (ABC-DLBCL). Sensitive lines show lost activation of the mTORC1 signaling complex and subsequent lost activation of cap-dependent protein translation. In addition, we characterize recurrent PIM1 protein-coding mutations found in DLBCL clinical samples and find most preserve the wild-type protein's ability to protect cells from apoptosis but do not bypass activity of PIM447. Pan-PIM inhibition therefore may have an important role to play in the therapy of selected ABC-DLBCL cases. PMID:27556513

  11. QSAR prediction of estrogen activity for a large set of diverse chemicals under the guidance of OECD principles.

    PubMed

    Liu, Huanxiang; Papa, Ester; Gramatica, Paola

    2006-11-01

    A large number of environmental chemicals, known as endocrine-disrupting chemicals, are suspected of disrupting endocrine functions by mimicking or antagonizing natural hormones, and such chemicals may pose a serious threat to the health of humans and wildlife. They are thought to act through a variety of mechanisms, mainly estrogen-receptor-mediated mechanisms of toxicity. However, it is practically impossible to perform thorough toxicological tests on all potential xenoestrogens, and thus, the quantitative structure--activity relationship (QSAR) provides a promising method for the estimation of a compound's estrogenic activity. Here, QSAR models of the estrogen receptor binding affinity of a large data set of heterogeneous chemicals have been built using theoretical molecular descriptors, giving full consideration to the new OECD principles in regulation for QSAR acceptability, during model construction and assessment. An unambiguous multiple linear regression (MLR) algorithm was used to build the models, and model predictive ability was validated by both internal and external validation. The applicability domain was checked by the leverage approach to verify prediction reliability. The results obtained using several validation paths indicate that the proposed QSAR model is robust and satisfactory, and can provide a feasible and practical tool for the rapid screening of the estrogen activity of organic compounds.

  12. Prediction of the adsorption capability onto activated carbon of a large data set of chemicals by local lazy regression method

    NASA Astrophysics Data System (ADS)

    Lei, Beilei; Ma, Yimeng; Li, Jiazhong; Liu, Huanxiang; Yao, Xiaojun; Gramatica, Paola

    2010-08-01

    Accurate quantitative structure-property relationship (QSPR) models based on a large data set containing a total of 3483 organic compounds were developed to predict chemicals' adsorption capability onto activated carbon in gas phrase. Both global multiple linear regression (MLR) method and local lazy regression (LLR) method were used to develop QSPR models. The results proved that LLR has prediction accuracy 10% higher than that of MLR model. By applying LLR method we can predict the test set (787 compounds) with Q2ext of 0.900 and root mean square error (RMSE) of 0.129. The accurate model based on this large data set could be useful to predict adsorption property of new compounds since such model covers a highly diverse structural space.

  13. Omega-3 fatty acids lower blood pressure by directly activating large-conductance Ca2+-dependent K+ channels

    PubMed Central

    Hoshi, Toshinori; Wissuwa, Bianka; Tian, Yutao; Tajima, Nobuyoshi; Xu, Rong; Bauer, Michael; Heinemann, Stefan H.; Hou, Shangwei

    2013-01-01

    Long-chain polyunsaturated omega-3 fatty acids such as docosahexaenoic acid (DHA), found abundantly in oily fish, may have diverse health-promoting effects, potentially protecting the immune, nervous, and cardiovascular systems. However, the mechanisms underlying the purported health-promoting effects of DHA remain largely unclear, in part because molecular signaling pathways and effectors of DHA are only beginning to be revealed. In vascular smooth muscle cells, large-conductance Ca2+- and voltage-activated K+ (BK) channels provide a critical vasodilatory influence. We report here that DHA with an EC50 of ∼500 nM rapidly and reversibly activates BK channels composed of the pore-forming Slo1 subunit and the auxiliary subunit β1, increasing currents by up to ∼20-fold. The DHA action is observed in cell-free patches and does not require voltage-sensor activation or Ca2+ binding but involves destabilization of the closed conformation of the ion conduction gate. DHA lowers blood pressure in anesthetized wild-type but not in Slo1 knockout mice. DHA ethyl ester, contained in dietary supplements, fails to activate BK channels and antagonizes the stimulatory effect of DHA. Slo1 BK channels are thus receptors for long-chain omega-3 fatty acids, and these fatty acids—unlike their ethyl ester derivatives—activate the channels and lower blood pressure. This finding has practical implications for the use of omega-3 fatty acids as nutraceuticals for the general public and also for the critically ill receiving omega-3–enriched formulas. PMID:23487785

  14. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems.

    PubMed

    Ghosh, Soumen; Cramer, Christopher J; Truhlar, Donald G; Gagliardi, Laura

    2017-04-01

    Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet-triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet-triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.

  15. The influence of hypotonicity on large-conductance calcium-activated potassium channels in human retinal pigment epithelial cells.

    PubMed

    Sheu, Shwu-Jiuan; Wu, Sheng-Nan; Hu, Dan-Ning; Chen, Jane-Fane

    2004-12-01

    The aim of this study was to characterize the effects of hypotonicity on the activity of large-conductance Ca(2+)-activated K+ (BK(Ca)) channels in human retinal pigment epithelial (RPE R-50) cells. Effects of hypotonicity on ion currents were investigated with the aid of the patch-clamp technique. A regulatory volume decrease in response to a hypotonic solution (200 mOsm/L) was observed that could be blunted by paxilline. In whole-cell current recordings, a hypotonic solution (200 mOsm/L) reversibly increased the amplitude of K+ outward currents (I(K)). The increase of I(K) could be reversed by iberiotoxin (200 nM), paxilline (1 microM), or tetrandrine (5 microM), but not by glibenclamide (10 microM), disulphonic acid (DIDS) (100 microM), or dequalinium dichloride (10 microM). In RPE R-50 cells pretreated with thapsigargin, aristolochic acid, or pertussis toxin, the increased amplitude of I(K) in response to hypotonicity was unaltered. In cell-attached patches, an increase in BK(Ca)-channel activity was observed during hypotonicity-induced cell swelling. The enhanced channel activity elicited under this condition was mainly mediated by an increase in the number of long-lived openings. These findings support the evidence for the coupling of volume swelling to the functional activity of BK(Ca) channels.

  16. Chromatin signatures at Notch-regulated enhancers reveal large-scale changes in H3K56ac upon activation.

    PubMed

    Skalska, Lenka; Stojnic, Robert; Li, Jinghua; Fischer, Bettina; Cerda-Moya, Gustavo; Sakai, Hiroshi; Tajbakhsh, Shahragim; Russell, Steven; Adryan, Boris; Bray, Sarah J

    2015-07-14

    The conserved Notch pathway functions in diverse developmental and disease-related processes, requiring mechanisms to ensure appropriate target selection and gene activation in each context. To investigate the influence of chromatin organisation and dynamics on the response to Notch signalling, we partitioned Drosophila chromatin using histone modifications and established the preferred chromatin conditions for binding of Su(H), the Notch pathway transcription factor. By manipulating activity of a co-operating factor, Lozenge/Runx, we showed that it can help facilitate these conditions. While many histone modifications were unchanged by Su(H) binding or Notch activation, we detected rapid changes in acetylation of H3K56 at Notch-regulated enhancers. This modification extended over large regions, required the histone acetyl-transferase CBP and was independent of transcription. Such rapid changes in H3K56 acetylation appear to be a conserved indicator of enhancer activation as they also occurred at the mammalian Notch-regulated Hey1 gene and at Drosophila ecdysone-regulated genes. This intriguing example of a core histone modification increasing over short timescales may therefore underpin changes in chromatin accessibility needed to promote transcription following signalling activation. © 2015 The Authors.

  17. Chromatin signatures at Notch-regulated enhancers reveal large-scale changes in H3K56ac upon activation

    PubMed Central

    Skalska, Lenka; Stojnic, Robert; Li, Jinghua; Fischer, Bettina; Cerda-Moya, Gustavo; Sakai, Hiroshi; Tajbakhsh, Shahragim; Russell, Steven; Adryan, Boris; Bray, Sarah J

    2015-01-01

    The conserved Notch pathway functions in diverse developmental and disease-related processes, requiring mechanisms to ensure appropriate target selection and gene activation in each context. To investigate the influence of chromatin organisation and dynamics on the response to Notch signalling, we partitioned Drosophila chromatin using histone modifications and established the preferred chromatin conditions for binding of Su(H), the Notch pathway transcription factor. By manipulating activity of a co-operating factor, Lozenge/Runx, we showed that it can help facilitate these conditions. While many histone modifications were unchanged by Su(H) binding or Notch activation, we detected rapid changes in acetylation of H3K56 at Notch-regulated enhancers. This modification extended over large regions, required the histone acetyl-transferase CBP and was independent of transcription. Such rapid changes in H3K56 acetylation appear to be a conserved indicator of enhancer activation as they also occurred at the mammalian Notch-regulated Hey1 gene and at Drosophila ecdysone-regulated genes. This intriguing example of a core histone modification increasing over short timescales may therefore underpin changes in chromatin accessibility needed to promote transcription following signalling activation. PMID:26069324

  18. Use of a fiber optic probe for organic species determination

    DOEpatents

    Ekechukwu, A.A.

    1996-12-10

    A fiber optic probe is described for remotely detecting the presence and concentration organic species in aqueous solutions. The probe includes a cylindrical housing with an organic species indicator, preferably diaminonaphthyl sulfonic acid adsorbed in a silica gel (DANS-modified gel), contained in the probe`s distal end. The probe admits aqueous solutions to the probe interior for mixing within the DANS-modified gel. An optical fiber transmits light through the DANS-modified gel while the indicator reacts with organic species present in the solution, thereby shifting the location of the fluorescent peak. The altered light is reflected to a receiving fiber that carries the light to a spectrophotometer or other analysis device. 5 figs.

  19. Raman Imaging with a Fiber-Coupled Multichannel Spectrograph

    PubMed Central

    Schmälzlin, Elmar; Moralejo, Benito; Rutowska, Monika; Monreal-Ibero, Ana; Sandin, Christer; Tarcea, Nicolae; Popp, Jürgen; Roth, Martin M.

    2014-01-01

    Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 × 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure. PMID:25420149

  20. Composite impact strength improvement through a fiber/matrix interphase

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Winters, W. E.

    1975-01-01

    Research was conducted to improve the impact strength and toughness of fiber/resin composites by means of a fiber coating interphase. Graphite fiber/epoxy resin composites were fabricated with four different fiber coating systems introduced in a matrix-fiber interphase. Two graphite fibers, a high strength and a high modulus type, were studied with the following coating systems: chemical vapor deposited boron, electroless nickel, a polyamide-imide resin and a thermoplastic polysulfone resin. Evaluation methods included the following tests: Izod, flexure, shear fracture toughness, longitudinal and transverse tensile, and transverse and longitudinal compression. No desirable changes could be effected with the high strength fiber, but significant improvements in impact performance were observed with the polyamide-imide resin coated high modulus fiber with no loss in composite modulus.

  1. A fiber-optic current sensor for aerospace applications

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Rose, A. H.; Tang, D.; Day, G. W.

    1990-01-01

    A robust, accurate, broadband, alternating current sensor using fiber optics is being developed for space applications at power frequencies as high as 20 kHz. It can also be used in low- and high-voltage 60-Hz terrestrial power systems and in 400-Hz aircraft systems. It is intrinsically EMI (electromagnetic interference) immune and has the added benefit of excellent isolation. The sensor uses the Faraday effect in optical fiber and standard polarimetric measurements to sense electrical current. The primary component of the sensor is a specially treated coil of single-mode optical fiber, through which the current carrying conductor passes. Improved precision is accomplished by temperature compensation by means of signals from a fiber-optic temperature sensor embedded in the sensing head. The authors report on the technology contained in the sensor and also relate the results of precision tests conducted at various temperatures within the wide operating range. The results of early EMI tests are shown.

  2. 3D simulation of drop impact on a fiber

    NASA Astrophysics Data System (ADS)

    Wang, Sheng; Desjardins, Olivier

    2016-11-01

    In this talk, an efficient numerical approach to simulate liquid-gas flows with moving contact lines is presented, then employed to investigate drop impact on a horizontal fiber. This approach combines a conservative level set method to capture the interface, an immersed boundary method to represent the curved boundary, and a curvature boundary method to treat the contact line. Simulations of drop-fiber impact are compared with experimental results with perticular focus on two key aspects: the critical velocity for a drop to be captured by a fiber, and the topology of the impacting drop. Numerical results show good agreement with experiments in predicting the critical velocity. A regime map of drop topology based on the Weber number and drop-to-fiber diameter ratio is compared to the experimental results.

  3. Transient SEUs in a fiber optic system for space applications

    NASA Technical Reports Server (NTRS)

    Label, Ken; Stassinopoulos, E. G.; Brucker, G. J.

    1991-01-01

    The results of an investigation on the SEU sensitivity for a fiber optic operating system are reported. Measurements were made on the upset cross sections for the system in static and dynamic modes of operation. The heavy ion SEU test facility at Brookhaven and the proton facility at Harvard University were used in this study. Cross sections were obtained for Honeywell transmitter and reciever devices operating in a system at a frequency of 100 kHz. Both devices were independently irradiated. The results show that the dynamic mode was the worst case, and the receiver was the most sensitive part type in the system. The threshold linear energy transfer (LET) for the receiver was determined to be 1.6 MeV sq cm/mg for the three input signals used in the tests, which were: a continuous high state, a low state, and a 100 kHz square wave.

  4. Polymer microcapsules with a fiber-reinforced nanocomposite shell.

    PubMed

    Sagis, Leonard M C; Ruiter, Riëlle de; Miranda, Francisco J Rossier; Ruiter, Jolet de; Schroën, Karin; Aelst, Adriaan C van; Kieft, Henk; Boom, Remko; Linden, Erik van der

    2008-03-04

    Polymer microcapsules can be used as controlled release systems in drugs or in foods. Using layer-by-layer adsorption of common food proteins and polysaccharides, we produced a new type of microcapsule with tunable strength and permeability. The shell consists of alternating layers of pectin and whey protein fibrils, yielding a fiber-reinforced nanocomposite shell. The strength can be tightly controlled by varying the number of layers or the density and length of the fibrils in the protein layers. The mechanical stability of these microcapsules appears to be superior to that of currently available multilayer capsules. The method involves only standard unit operations and has the potential for scaling up to industrial production volumes.

  5. Buckling of a fiber bundle embedded in epoxy

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Sohi, M. M.

    1986-01-01

    Buckling of a fiber bundle embedded in epoxy resin was studied to gain insight into compressive failure mechanisms in unidirectional composites. The fibers used were E-glass, T300 graphite, T700 graphite, and P75 graphite. These fibers were combined with two different resins: Epon 815/V140 and Epon 828/Z. In both resins the failure mode of the bundle was found to be microbuckling of fibers for the first three types of fibers; however, the high-modulus P75 fibers failed in shear without any sign of microbuckling. The strains at which microbuckling occurred were higher than the compressive failure strains of the corresponding unidirectional composites. In the soft resin, Epon 815/V140, fibers buckled at lower strains than in the stiff resin, Epon 828/Z. The buckling strains and the segment lengths followed the trends predicted for a single filament embedded in an infinite matrix.

  6. A fiber-optic current sensor for aerospace applications

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Rose, A. H.; Tang, D.; Day, G. W.

    1990-01-01

    A robust, accurate, broadband, alternating current sensor using fiber optics is being developed for space applications at power frequencies as high as 20 kHz. It can also be used in low- and high-voltage 60-Hz terrestrial power systems and in 400-Hz aircraft systems. It is intrinsically EMI (electromagnetic interference) immune and has the added benefit of excellent isolation. The sensor uses the Faraday effect in optical fiber and standard polarimetric measurements to sense electrical current. The primary component of the sensor is a specially treated coil of single-mode optical fiber, through which the current carrying conductor passes. Improved precision is accomplished by temperature compensation by means of signals from a fiber-optic temperature sensor embedded in the sensing head. The authors report on the technology contained in the sensor and also relate the results of precision tests conducted at various temperatures within the wide operating range. The results of early EMI tests are shown.

  7. Velocity difference measurement with a fiber-optic coupler.

    PubMed

    Du, Y; Ackerson, B J; Tong, P

    1998-09-01

    Two single-mode fibers collect light with the same scattered wave vector from two spatially separated regions in a sample. These regions are illuminated by a single coherent laser beam, so that the collected signals interfere when combined by means of a fiber-optic coupler, before they are directed to a photomultiplier tube. The fibers and the coupler are polarization preserving to guarantee a high signal-to-noise ratio. The measured intensity fluctuations are used to determine the velocity difference omega v(L) for spatial separations L in the sample. Specifically, an intensity autocorrelation function is calculated theoretically for rigid body rotation and is tested experimentally. Experimental results span two orders of magnitude in L and agree with theoretical predictions with an error of less than 5%. This new technique will be very useful in the study of turbulent flow and particle settling dynamics.

  8. Design of a fiber-optic multiphoton microscopy handheld probe

    PubMed Central

    Zhao, Yuan; Sheng, Mingyu; Huang, Lin; Tang, Shuo

    2016-01-01

    We have developed a fiber-optic multiphoton microscopy (MPM) system with handheld probe using femtosecond fiber laser. Here we present the detailed optical design and analysis of the handheld probe. The optical systems using Lightpath 352140 and 352150 as objective lens were analyzed. A custom objective module that includes Lightpath 355392 and two customized corrective lenses was designed. Their performances were compared by wavefront error, field curvature, astigmatism, F-θ error, and tolerance in Zemax simulation. Tolerance analysis predicted the focal spot size to be 1.13, 1.19 and 0.83 µm, respectively. Lightpath 352140 and 352150 were implemented in experiment and the measured lateral resolution was 1.22 and 1.3 µm, respectively, which matched with the prediction. MPM imaging by the handheld probe were conducted on leaf, fish scale and rat tail tendon. The MPM resolution can potentially be improved by the custom objective module. PMID:27699109

  9. Preliminary Development of a Fiber Optic Sensor for Measuring Bilirubin

    PubMed Central

    Babin, Steven M; Sova, Raymond M

    2014-01-01

    Preliminary development of a fiber optic bilirubin sensor is described, where an unclad sensing portion is used to provide evanescent wave interaction of the transmitted light with the chemical environment. By using a wavelength corresponding to a bilirubin absorption peak, the Beer–Lambert Law can be used to relate the concentration of bilirubin surrounding the sensing portion to the amount of absorbed light. Initial testing in vitro suggests that the sensor response is consistent with the results of bulk absorption measurements as well as the Beer–Lambert Law. In addition, it is found that conjugated and unconjugated bilirubin have different peak absorption wavelengths, so that two optical frequencies may potentially be used to measure both types of bilirubin. Future development of this device could provide a means of real-time, point-of-care monitoring of intravenous bilirubin in critical care neonates with hyperbilirubinemia. PMID:25057239

  10. Dietary fibres modulate the composition and activity of butyrate-producing bacteria in the large intestine of suckling piglets.

    PubMed

    Mu, Chunlong; Zhang, Lingli; He, Xiangyu; Smidt, Hauke; Zhu, Weiyun

    2017-02-04

    Dietary fibres have been shown to affect early-life microbiota colonization in the large intestine of suckling piglets, however, much less is known as to whether they also modulate the composition and activity of butyrate-producing bacteria. Here, we investigated the effect of dietary fibres on the abundance, composition, and activity of butyrate-producing bacteria in suckling piglets. Piglets were fed a control diet or creep feeds containing alfalfa, wheat bran, or pure cellulose, respectively, from postnatal day 7 to 22. Large intestinal digesta and mucosa samples were collected for quantitative analysis of bacterial group-specific 16S ribosomal RNA- and butyrate production-related genes, and digesta samples for quantification of short-chain fatty acids. The alfalfa diet increased (P < 0.05) Clostridium cluster XIVa abundance, copies of genes encoding proteins involved in butyrate production (butyryl-CoA:acetate CoA-transferase, butyrate kinase), and butyrate concentration compared to the wheat bran diet in the digesta of the proximal colon. In the distal colonic digesta, animals fed the alfalfa diet had the highest number of butyryl-CoA:acetate CoA-transferase gene copies (P < 0.05) and numerically the highest butyrate concentration, albeit not significant (P > 0.05), compared to other groups. In the distal colonic mucosa, the cellulose diet increased (P < 0.05) the abundance of Clostridium cluster XIVa and copies of the butyryl-CoA:acetate CoA-transferase gene compared to the alfalfa diet. These results indicated that dietary fibres modulate the abundance and activity of butyrate-producing bacteria in the large intestine of suckling piglets, and that a moderate supplementation of alfalfa and cellulose may benefit early-life gut health through the delivery of butyrate to the mucosa.

  11. Establishing a fiber-optic-based optical neural interface.

    PubMed

    Adamantidis, Antoine R; Zhang, Feng; de Lecea, Luis; Deisseroth, Karl

    2014-08-01

    Selective expression of opsins in genetically defined neurons makes it possible to control a subset of neurons without affecting nearby cells and processes in the intact brain, but light must still be delivered to the target brain structure. Light scattering limits the delivery of light from the surface of the brain. For this reason, we have developed a fiber-optic-based optical neural interface (ONI), which allows optical access to any brain structure in freely moving mammals. The ONI system is constructed by modifying the small animal cannula system from PlasticsOne. The system for bilateral stimulation consists of a bilateral cannula guide that has been stereotactically implanted over the target brain region, a screw cap for securing the optical fiber to the animal's head, a fiber guard modified from the internal cannula adapter, and a bare fiber whose length is customized based on the depth of the target region. For unilateral stimulation, a single-fiber system can be constructed using unilateral cannula parts from PlasticsOne. We describe here the preparation of the bilateral ONI system and its use in optical stimulation of the mouse or rat brain. Delivery of opsin-expressing virus and implantation of the ONI may be conducted in the same surgical session; alternatively, with a transgenic animal no opsin virus is delivered during the surgery. Similar procedures are useful for deep or superficial injections (even for neocortical targets, although in some cases surface light-emitting diodes or cortex-apposed fibers can be used for the most superficial cortical targets).

  12. Observing large-scale solar surface flows with GONG: Investigation of a key element in solar activity buildup

    NASA Technical Reports Server (NTRS)

    Beck, John G.; Simon, George W.; Hathaway, David H.

    1996-01-01

    The Global Oscillation Network Group (GONG) solar telescope network has begun regular operations, and will provide continuous Doppler images of large-scale nearly-steady motions at the solar surface, primarily those due to supergranulation. Not only the Sun's well-known magnetic network, but also flux diffusion, dispersal, and concentration at the surface appear to be controlled by supergranulation. Through such magnetoconvective interactions, magnetic stresses develop, leading to solar activity. We show a Doppler movie made from a 45.5 hr time series obtained 1995 May 9-10 using data from three of the six GONG sites (Learmonth, Tenerife, Tucson), to demonstrate the capability of this system.

  13. North-south asymmetry in small and large sunspot group activity and violation of even-odd solar cycle rule

    NASA Astrophysics Data System (ADS)

    Javaraiah, J.

    2016-07-01

    According to Gnevyshev-Ohl (G-O) rule an odd-numbered cycle is stronger than its preceding even-numbered cycle. In the modern time the cycle pair (22, 23) violated this rule. By using the combined Greenwich Photoheliographic Results (GPR) and Solar Optical Observing Network (SOON) sunspot group data during the period 1874-2015, and Debrecen Photoheliographic Data (DPD) of sunspot groups during the period 1974-2015, here we have found that the solar cycle pair (22, 23) violated the G-O rule because, besides during cycle 23 a large deficiency of small sunspot groups in both the northern and the southern hemispheres, during cycle 22 a large abundance of small sunspot groups in the southern hemisphere. In the case of large and small sunspot groups the cycle pair (22, 23) violated the G-O rule in the northern and southern hemispheres, respectively, suggesting the north-south asymmetry in solar activity has a significant contribution in the violation of G-O rule. The amplitude of solar cycle 24 is smaller than that of solar cycle 23. However, Coronal Mass Ejections (CMEs) rate in the rising phases of the cycles 23 and 24 are almost same (even slightly large in cycle 24). From both the SOON and the DPD sunspot group data here we have also found that on the average the ratio of the number (counts) of large sunspot groups to the number of small sunspot groups is larger in the rising phase of cycle 24 than that in the corresponding phase of cycle 23. We suggest this could be a potential reason for the aforesaid discrepancy in the CME rates during the rising phases of cycles 23 and 24. These results have significant implication on solar cycle mechanism.

  14. Reconciling the discrepancies on the involvement of large-conductance Ca(2+)-activated K channels in glioblastoma cell migration.

    PubMed

    Catacuzzeno, Luigi; Caramia, Martino; Sforna, Luigi; Belia, Silvia; Guglielmi, Luca; D'Adamo, Maria Cristina; Pessia, Mauro; Franciolini, Fabio

    2015-01-01

    Glioblastoma (GBM) is the most common and aggressive primary brain tumor, and is notable for spreading so effectively through the brain parenchyma to make complete surgical resection virtually impossible, and prospect of life dismal. Several ion channels have been involved in GBM migration and invasion, due to their critical role in supporting volume changes and Ca(2+) influx occuring during the process. The large-conductance, Ca(2+)-activated K (BK) channels, markedly overexpressed in biopsies of patients with GBMs and in GBM cell lines, have attracted much interest and have been suggested to play a central role in cell migration and invasion as candidate channels for providing the ion efflux and consequent water extrusion that allow cell shrinkage during migration. Available experimental data on the role of BK channel in migration and invasion are not consistent though. While BK channels block typically resulted in inhibition of cell migration or in no effect, their activation would either enhance or inhibit the process. This short review reexamines the relevant available data on the topic, and presents a unifying paradigm capable of reconciling present discrepancies. According to this paradigm, BK channels would not contribute to migration under conditions where the [Ca(2+)] i is too low for their activation. They will instead positively contribute to migration for intermediate [Ca(2+)] i , insufficient as such to activate BK channels, but capable of predisposing them to cyclic activation following oscillatory [Ca(2+)] i increases. Finally, steadily active BK channels because of prolonged high [Ca(2+)] i would inhibit migration as their steady activity would be unsuitable to match the cyclic cell volume changes needed for proper cell migration.

  15. Methods for chronic recording of EMG activity from large numbers of hindlimb muscles in awake rhesus macaques

    PubMed Central

    Hudson, Heather M.; Griffin, Darcy M.; Belhaj-Saïf, Abderraouf; Lee, Sang-Pil; Cheney, Paul D.

    2010-01-01

    Studies of the neural control of movement often rely on the ability to record EMG activity during natural behavioral tasks over long periods of time. Increasing the number of recorded muscles and the time over which recordings are made allows more rigorous answers to many questions related to the descending control of motor output. Chronic recording of EMG activity from multiple hindlimb muscles has been reported in the cat but few studies have been done in non-human primates. This paper describes two chronic EMG implant methods that are minimally invasive, relatively non-traumatic and capable of recording from large numbers of hindlimb muscles simultaneously for periods of many months to years. PMID:20346976

  16. The effects of season and sand mining activities on thermal regime and water quality in a large shallow tropical lake.

    PubMed

    Sharip, Zati; Zaki, Ahmad Taqiyuddin Ahmad

    2014-08-01

    Thermal structure and water quality in a large and shallow lake in Malaysia were studied between January 2012 and June 2013 in order to understand variations in relation to water level fluctuations and in-stream mining activities. Environmental variables, namely temperature, turbidity, dissolved oxygen, pH, electrical conductivity, chlorophyll-A and transparency, were measured using a multi-parameter probe and a Secchi disk. Measurements of environmental variables were performed at 0.1 m intervals from the surface to the bottom of the lake during the dry and wet seasons. High water level and strong solar radiation increased temperature stratification. River discharges during the wet season, and unsustainable sand mining activities led to an increased turbidity exceeding 100 NTU, and reduced transparency, which changed the temperature variation and subsequently altered the water quality pattern.

  17. Product-selective blot: a technique for measuring enzyme activities in large numbers of samples and in native electrophoresis gels

    SciTech Connect

    Thompson, G.A.; Davies, H.M.; McDonald, N.

    1985-08-01

    A method termed product-selective blotting has been developed for screening large numbers of samples for enzyme activity. The technique is particularly well suited to detection of enzymes in native electrophoresis gels. The principle of the method was demonstrated by blotting samples from glutaminase or glutamate synthase reactions into an agarose gel embedded with ion-exchange resin under conditions favoring binding of product (glutamate) over substrates and other substances in the reaction mixture. After washes to remove these unbound substances, the product was measured using either fluorometric staining or radiometric techniques. Glutaminase activity in native electrophoresis gels was visualized by a related procedure in which substrates and products from reactions run in the electrophoresis gel were blotted directly into a resin-containing image gel. Considering the selective-binding materials available for use in the image gel, along with the possible detection systems, this method has potentially broad application.

  18. Characterization of large area ZnS(Ag) detector for gross alpha and beta activity measurements in tap water plants

    SciTech Connect

    Lunardon, M.; Cester, D.; Mistura, G.; Moretto, S.; Stevanato, L.; Viesti, G.; Schotanus, P.; Bodewits, E.

    2015-07-01

    In this work we present the characterization of a large area 200 x 200 mm{sup 2} EJ-444 scintillation detector to be used for monitoring gross alpha and beta activity in tap water plants. Specific tests were performed to determine the best setup to readout the light from the detector side in order to have the possibility to stack many detectors and get a compact device with total active area of the order of 1 m{sup 2}. Alpha/Beta discrimination, efficiency and homogeneity tests were carried out with alpha and beta sources. Background from ambient radioactivity was measured as well. Alpha/beta real-time monitoring in drinking water is a goal of the EU project TAWARA{sub R}TM. (authors)

  19. Large-conductance Ca²⁺-activated potassium channel in mitochondria of endothelial EA.hy926 cells.

    PubMed

    Bednarczyk, Piotr; Koziel, Agnieszka; Jarmuszkiewicz, Wieslawa; Szewczyk, Adam

    2013-06-01

    In the present study, we describe the existence of a large-conductance Ca²⁺-activated potassium (BKCa) channel in the mitochondria of the human endothelial cell line EA.hy926. A single-channel current was recorded from endothelial mitoplasts (i.e., inner mitochondrial membrane) using the patch-clamp technique in the mitoplast-attached mode. A potassium-selective current was recorded with a mean conductance equal to 270 ± 10 pS in a symmetrical 150/150 mM KCl isotonic solution. The channel activity, which was determined as the open probability, increased with the addition of calcium ions and the potassium channel opener NS1619. Conversely, the activity of the channel was irreversibly blocked by paxilline and iberiotoxin, BKCa channel inhibitors. The open-state probability was found to be voltage dependent. The substances known to modulate BKCa channel activity influenced the bioenergetics of mitochondria isolated from human endothelial EA.hy926 cells. In isolated mitochondria, 100 μM Ca²⁺, 10 μM NS1619, and 0.5 μM NS11021 depolarized the mitochondrial membrane potential and stimulated nonphosphorylating respiration. These effects were blocked by iberiotoxin and paxilline in a potassium-dependent manner. Under phosphorylating conditions, NS1619-induced, iberiotoxin-sensitive uncoupling diverted energy from ATP synthesis during the phosphorylating respiration of the endothelial mitochondria. Immunological analysis with antibodies raised against proteins of the plasma membrane BKCa channel identified a pore-forming α-subunit and an auxiliary β₂-subunit of the channel in the endothelial mitochondrial inner membrane. In conclusion, we show for the first time that the inner mitochondrial membrane in human endothelial EA.hy926 cells contains a large-conductance calcium-dependent potassium channel with properties similar to those of the surface membrane BKCa channel.

  20. Large, binge-type meals of high fat diet change feeding behaviour and entrain food anticipatory activity in mice*

    PubMed Central

    Bake, T.; Murphy, M.; Morgan, D.G.A.; Mercer, J.G.

    2014-01-01

    Male C57BL/6 mice fed ad libitum on control diet but allowed access to a palatable high fat diet (HFD) for 2 h a day during the mid-dark phase rapidly adapt their feeding behaviour and can consume nearly 80% of their daily caloric intake during this 2 h-scheduled feed. We assessed food intake microstructure and meal pattern, and locomotor activity and rearing as markers of food anticipatory activity (FAA). Schedule fed mice reduced their caloric intake from control diet during the first hours of the dark phase but not during the 3-h period immediately preceding the scheduled feed. Large meal/binge-like eating behaviour during the 2-h scheduled feed was characterised by increases in both meal number and meal size. Rearing was increased during the 2-h period running up to scheduled feeding while locomotor activity started to increase 1 h before, indicating that schedule-fed mice display FAA. Meal number and physical activity changes were sustained when HFD was withheld during the anticipated scheduled feeding period, and mice immediately binged when HFD was represented after a week of this “withdrawal” period. These findings provide important context to our previous studies suggesting that energy balance systems in the hypothalamus are not responsible for driving these large, binge-type meals. Evidence of FAA in HFD dark phase schedule-fed mice implicates anticipatory processes in binge eating that do not involve immediately preceding hypophagia or regulatory homeostatic signalling. PMID:24631639

  1. Large, binge-type meals of high fat diet change feeding behaviour and entrain food anticipatory activity in mice.

    PubMed

    Bake, T; Murphy, M; Morgan, D G A; Mercer, J G

    2014-06-01

    Male C57BL/6 mice fed ad libitum on control diet but allowed access to a palatable high fat diet (HFD) for 2 h a day during the mid-dark phase rapidly adapt their feeding behaviour and can consume nearly 80% of their daily caloric intake during this 2 h-scheduled feed. We assessed food intake microstructure and meal pattern, and locomotor activity and rearing as markers of food anticipatory activity (FAA). Schedule fed mice reduced their caloric intake from control diet during the first hours of the dark phase but not during the 3-h period immediately preceding the scheduled feed. Large meal/binge-like eating behaviour during the 2-h scheduled feed was characterised by increases in both meal number and meal size. Rearing was increased during the 2-h period running up to scheduled feeding while locomotor activity started to increase 1 h before, indicating that schedule-fed mice display FAA. Meal number and physical activity changes were sustained when HFD was withheld during the anticipated scheduled feeding period, and mice immediately binged when HFD was represented after a week of this "withdrawal" period. These findings provide important context to our previous studies suggesting that energy balance systems in the hypothalamus are not responsible for driving these large, binge-type meals. Evidence of FAA in HFD dark phase schedule-fed mice implicates anticipatory processes in binge eating that do not involve immediately preceding hypophagia or regulatory homeostatic signalling. Copyright © 2014. Published by Elsevier Ltd.

  2. Testing promotes long-term learning via stabilizing activation patterns in a large network of brain areas.

    PubMed

    Keresztes, Attila; Kaiser, Daniel; Kovács, Gyula; Racsmány, Mihály

    2014-11-01

    The testing effect refers to the phenomenon that repeated retrieval of memories promotes better long-term retention than repeated study. To investigate the neural correlates of the testing effect, we used event-related functional magnetic resonance imaging methods while participants performed a cued recall task. Prior to the neuroimaging experiment, participants learned Swahili-German word pairs, then half of the word pairs were repeatedly studied, whereas the other half were repeatedly tested. For half of the participants, the neuroimaging experiment was performed immediately after the learning phase; a 1-week retention interval was inserted for the other half of the participants. We found that a large network of areas identified in a separate 2-back functional localizer scan were active during the final recall of the word pair associations. Importantly, the learning strategy (retest or restudy) of the word pairs determined the manner in which the retention interval affected the activations within this network. Recall of previously restudied memories was accompanied by reduced activation within this network at long retention intervals, but no reduction was observed for previously retested memories. We suggest that retrieval promotes learning via stabilizing cue-related activation patterns in a network of areas usually associated with cognitive and attentional control functions.

  3. Distinct contributions of small and large conductance Ca2+-activated K+ channels to rat Purkinje neuron function

    PubMed Central

    Edgerton, Jeremy R; Reinhart, Peter H

    2003-01-01

    The cerebellum is important for many aspects of behaviour, from posture maintenance and goal-oriented reaching movements to timing tasks and certain forms of learning. In every case, information flowing through the cerebellum passes through Purkinje neurons, which receive input from the two primary cerebellar afferents and generate continuous streams of action potentials that constitute the sole output from the cerebellar cortex to the deep nuclei. The tonic firing behaviour observed in Purkinje neurons in vivo is maintained in brain slices even when synaptic inputs are blocked, suggesting that Purkinje neuron activity relies to a significant extent on intrinsic conductances. Previous research has suggested that the interplay between Ca2+ currents and Ca2+-activated K+ channels (KCa channels) is important for Purkinje cell activity, but how many different KCa channel types are present and what each channel type contributes to cell behaviour remains unclear. In order to better understand the ionic mechanisms that control the behaviour of these neurons, we investigated the effects of different Ca2+ channel and KCa channel antagonists on Purkinje neurons in acute slices of rat cerebellum. Our data show that Ca2+ entering through P-type voltage-gated Ca2+ channels activates both small-conductance (SK) and large-conductance (BK) KCa channels. SK channels play a role in setting the intrinsic firing frequency, while BK channels regulate action potential shape and may contribute to the unique climbing fibre response. PMID:12576503

  4. Density matrix renormalization group (DMRG) method as a common tool for large active-space CASSCF/CASPT2 calculations

    NASA Astrophysics Data System (ADS)

    Nakatani, Naoki; Guo, Sheng

    2017-03-01

    This paper describes an interface between the density matrix renormalization group (DMRG) method and the complete active-space self-consistent field (CASSCF) method and its analytical gradient, as well as an extension to the second-order perturbation theory (CASPT2) method. This interfacing allows large active-space multi-reference computations to be easily performed. The interface and its extension are both implemented in terms of reduced density matrices (RDMs) which can be efficiently computed via the DMRG sweep algorithm. We also present benchmark results showing that, in practice, the DMRG-CASSCF calculations scale with active-space size in a polynomial manner in the case of quasi-1D systems. Geometry optimization of a binuclear iron-sulfur cluster using the DMRG-CASSCF analytical gradient is demonstrated, indicating that the inclusion of the valence p-orbitals of sulfur and double-shell d-orbitals of iron lead to non-negligible changes in the geometry compared to the results of small active-space calculations. With the exception of the selection of M values, many computational settings in these practical DMRG calculations have been tuned and black-boxed in our interface, and so the resulting DMRG-CASSCF and DMRG-CASPT2 calculations are now available to novice users as a common tool to compute strongly correlated electronic wavefunctions.

  5. External copper inhibits the activity of the large-conductance calcium- and voltage-sensitive potassium channel from skeletal muscle.

    PubMed

    Morera, F J; Wolff, D; Vergara, C

    2003-03-01

    We have characterized the effect of external copper on the gating properties of the large-conductance calcium- and voltage-sensitive potassium channel from skeletal muscle, incorporated into artificial bilayers. The effect of Cu2+ was evaluated as changes in the gating kinetic properties of the channel after the addition of this ion. We found that, from concentrations of 20 microM and up, copper induced a concentration- and time-dependent decrease in channel open probability. The inhibition of channel activity by Cu2+ could not be reversed by washing or by addition of the copper chelator, bathocuproinedisulfonic acid. However, channel activity was appreciably restored by the sulfhydryl reducing agent dithiothreitol. The effect of copper was specific since other transition metal divalent cations such as Ni2+, Zn2+ or Cd2+ did not affect BK(Ca) channel activity in the same concentration range. These results suggest that external Cu2+-induced inhibition of channel activity was due to direct or indirect oxidation of key amino-acid sulfhydryl groups that might have a role in channel gating.

  6. Measuring the thermal sensitivity of a fiber Fabry-Pérot interferometer

    NASA Astrophysics Data System (ADS)

    Jennings, Jeff; Halverson, Samuel; Diddams, Scott A.; Terrien, Ryan; Ycas, Gabriel; Mahadevan, Suvrath

    2016-08-01

    We introduce a general technique for frequency stability characterization of Fabry-Perot etalons that are being explored for astronomical spectrograph calibration. In our approach a frequency-stabilized laser frequency comb is employed as a reference for a scanning CW laser measurement of the temperature sensitivity of a fiber Fabry-Perot interferometer (FFP). For an in-house constructed, actively stabilized FFP, we observe the thermal sensitivity of a resonance mode at 1319 nm of 7.4 GHz C-1, which corresponds to a fractional thermal sensitivity of 3.2 × 10-5 C-1. We compare these results to a simple model and discuss further the materials construction and stabilization of the FFP. Our measurement technique is one step toward a broad characterization of Fabry-Perot instruments, and this FFP in particular is currently being investigated as a wavelength calibration source in precision radial velocity spectroscopy to discover terrestrial-mass exoplanets.

  7. The Properties of Large Amplitude Whistler Mode Waves in the Magnetosphere: Propagation and Relationship with Geomagnetic Activity

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Wygant, J. R.; Goetz, K.; Breneman, A.; Kersten, K.

    2011-01-01

    Wepresent resultsof a studyof the characteristicsof very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 RE using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had !80 mV/m peak!to!peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had !0.8 nT peak!to!peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20 of the ambient magnetic field, though some are more oblique (up to "50 ). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (^8 nT peak!to!peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ^300 mW/m2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons.

  8. Alternatively spliced C-terminal domains regulate the surface expression of large conductance calcium-activated potassium (BKCa) channels

    PubMed Central

    Kim, Eun Young; Ridgway, Lon D.; Zou, Shengwei; Chiu, Yu-Hsin; Dryer, Stuart E.

    2007-01-01

    The Slo1 gene, also known as KCNMA1, encodes the pore-forming subunits of large-conductance Ca2+-activated K+ (BKCa) channels. Products of this gene are widely expressed in vertebrate tissues, and occur in a large number (≥ 20) of alternatively spliced variants that vary in their gating properties, susceptibility to modulation, and trafficking to the plasma membrane. Motifs in the large cytoplasmic C-terminal are especially important in determining the functional properties of BKCa channels. Here we report that chick ciliary ganglion neurons express transcripts and proteins of two Slo1 splice variants that differ at the extreme C-terminal. We refer to these variants as VEDEC and QEDRL (or QEERL for the orthologous mammalian versions), after the five terminal amino acid residues in each isoform. Individual ciliary ganglion neurons preferentially express these variants in different subcellular compartments. Moreover, QEERL channels show markedly higher levels of constitutive expression on the plasma membrane than VEDEC channels in HEK293T and NG108-15 cells. However, growth factor treatment can stimulate surface expression of VEDEC channels to levels comparable to those seen with QEERL. In addition, we show that co-expression of a soluble protein comprised of VEDEC C-terminal tail residues markedly increases cell surface expression of full-length VEDEC channels, suggesting that this region binds to proteins that cause retention of the these channels in intracellular stores. PMID:17478049

  9. Property of large conductance Ca(2+)-activated K+ channels from Fasciola hepatica incorporated into planar lipid bilayer.

    PubMed

    Jang, Jung Hee; Park, Jin Bong; Kim, Sun Don; Lee, So Yeong; Hong, Sung-Jong; Ryu, Pan Dong

    2012-05-25

    Fasciola hepatica causes biliary epithelial hyperplasia and obstructive jaundice in humans and animals. Using a planar lipid bilayer technique, we further characterized the single channel property of large conductance K(+)-permeable channels that were previously identified from F. hepatica. The single channel conductance was 254.7±17.9 pS under a symmetrical 200/200 mM (cis/trans) KCl gradient. Open state probability (P(o)) varied from channel to channel at a given membrane potential and Ca(2+) concentration, but increased with voltage (-60 to +40 mV) and cis Ca(2+) (1-200 μM). Under a near bi-ionic condition of 200 mM [K(+)](cis)/200 mM [Na(+)](trans), the permeability ratio of K(+) to Na(+) was 5.0. Charybdotoxin (1 μM) inhibited P(o), whereas tetraethylammonium reduced the conductance (K(D)=67.8mM). Taken together, the results show that the single channel properties of the large conductance K(+)-permeable channels in F. hepatica are similar to those of large conductance Ca(2+)-activated K(+) (BK) channels in general, but distinct from typical BK channels in the extent of voltage- and Ca(2+)-dependence, as well as permeability to Na(+). This study further reveals a variant BK channel in F. hepatica that could serve as a new drug target to treat fascioliasis.

  10. Heart rate variability characteristics in a large group of active-duty Marines and relationship to posttraumatic stress

    PubMed Central

    Minassian, Arpi; Geyer, Mark A.; Baker, Dewleen G.; Nievergelt, Caroline M.; O'Connor, Daniel T.; Risbrough, Victoria B.

    2014-01-01

    Objective Heart rate variability (HRV), thought to reflect autonomic nervous system function, is lowered in conditions such as posttraumatic stress disorder (PTSD). The potential confounding effects of traumatic brain injury (TBI) and depression in the relationship between HRV and PTSD have not been elucidated in a large cohort of military service members. Here we describe HRV associations with stress disorder symptoms in a large study of Marines, while accounting for well-known covariates of HRV and PTSD including TBI and depression. Methods Four battalions of male active-duty Marines (N=2430) were assessed 1-2 months prior to a combat deployment. HRV was measured during 5 minutes of rest. Depression and PTSD were assessed using the Beck Depression Inventory and Clinician Administered PTSD scale respectively. Results After accounting for covariates including TBI, a regression indicated that lower levels of high frequency (HF) HRV were associated with a diagnosis of PTSD (beta = -.20, p=.035). Depression and PTSD severity were correlated (r= .49, p <.001), however participants with PTSD but relatively low depression scores exhibited reduced HF compared to controls (p=.012). Marines with deployment experience (n=1254) had lower HRV than those with no experience (p = .033). Conclusions This cross-sectional analysis of a large cohort supports associations between PTSD and reduced HRV when accounting for TBI and depression symptoms. Future post-deployment assessments will be used to determine whether pre-deployment HRV can predict vulnerability and resilience to the serious psychological and physiological consequences of combat exposure. PMID:24804881

  11. Optical generation of millimeter-wave pulses using a fiber Bragg grating in a fiber-optics system.

    PubMed

    Ye, Qing; Qu, Ronghui; Fang, Zujie

    2007-04-10

    A scheme is proposed to transform an optical pulse into a millimeter-wave frequency modulation pulse by using a weak fiber Bragg grating (FBG) in a fiber-optics system. The Fourier transformation method is used to obtain the required spectrum response function of the FBG for the Gaussian pulse, soliton pulse, and Lorenz shape pulse. On the condition of the first-order Born approximation of the weak fiber grating, the relation of the refractive index distribution and the spectrum response function of the FBG satisfies the Fourier transformation, and the corresponding refractive index distribution forms are obtained for single-frequency modulation and linear-frequency modulation millimeter-wave pulse generation. The performances of the designed fiber gratings are also studied by a numerical simulation method for a supershort pulse transmission.

  12. Analysis of disease activity and response to treatment in a large Spanish cohort of patients with systemic lupus erythematosus.

    PubMed

    Pego-Reigosa, J M; Rúa-Figueroa, Í; López-Longo, F J; Galindo-Izquierdo, M; Calvo-Alén, J; Olivé-Marqués, A; del Campo, V; García-Yébenes, M J; Loza-Santamaría, E; Blanco, R; Melero-González, R; Vela-Casasempere, P; Otón-Sánchez, T; Tomero-Muriel, E; Uriarte-Isacelaya, E; Fito-Manteca, M C; Freire-González, M; Narváez, J; Fernández-Nebro, A; Zea-Mendoza, A; Rosas, J; Carlos Rosas, J

    2015-06-01

    The objectives of this paper are to study the impact of disease activity in a large cohort of patients with systemic lupus erythematosus (SLE) and estimate the rate of response to therapies. We conducted a nationwide, retrospective, multicenter, cross-sectional cohort study of 3658 SLE patients. Data on demographics, disease characteristics: activity (SELENA-SLEDAI), damage, severity, hospitalizations and therapies were collected. Factors associated with refractory disease were identified by logistic regression. A total of 3658 patients (90% female; median SLE duration (interquartile range): 10.4 years (5.3-17.1)) were included. At the time of their last evaluation, 14.7% of the patients had moderate-severe SLE (SELENA-SLEDAI score ≥6). There were 1954 (53.4%) patients who were hospitalized for activity at least once over the course of the disease. At some stage, 84.6% and 78.8% of the patients received glucocorticoids and antimalarials, respectively, and 51.3% of the patients received at least one immunosuppressant. Owing to either toxicity or ineffectiveness, cyclophosphamide was withdrawn in 21.5% of the cases, mycophenolate mofetil in 24.9%, azathioprine in 40.2% and methotrexate in 46.8%. At some stage, 7.3% of the patients received at least one biologic. A total of 898 (24.5%) patients had refractory SLE at some stage. Renal, neuropsychiatric, vasculitic, hematological and musculoskeletal involvement, a younger age at diagnosis and male gender were associated with refractory disease. A significant percentage of patients have moderately-to-severely active SLE at some stage. Disease activity has a big impact in terms of need for treatment and cause of hospitalization. The effectiveness of the standard therapies for reducing disease activity is clearly insufficient. Some clinical features are associated with refractory SLE. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  13. When and where the aftershock activity was depressed: Contrasting decay patterns of the proximate large earthquakes in southern California

    USGS Publications Warehouse

    Ogata, Y.; Jones, L.M.; Toda, S.

    2003-01-01

    Seismic quiescence has attracted attention as a possible precursor to a large earthquake. However, sensitive detection of quiescence requires accurate modeling of normal aftershock activity. We apply the epidemic-type aftershock sequence (ETAS) model that is a natural extension of the modified Omori formula for aftershock decay, allowing further clusters (secondary aftershocks) within an aftershock sequence. The Hector Mine aftershock activity has been normal, relative to the decay predicted by the ETAS model during the 14 months of available data. In contrast, although the aftershock sequence of the 1992 Landers earthquake (M = 7.3), including the 1992 Big Bear earthquake (M = 6.4) and its aftershocks, fits very well to the ETAS up until about 6 months after the main shock, the activity showed clear lowering relative to the modeled rate (relative quiescence) and lasted nearly 7 years, leading up to the Hector Mine earthquake (M = 7.1) in 1999. Specifically, the relative quiescence occurred only in the shallow aftershock activity, down to depths of 5-6 km. The sequence of deeper events showed clear, normal aftershock activity well fitted to the ETAS throughout the whole period. We argue several physical explanations for these results. Among them, we strongly suspect aseismic slips within the Hector Mine rupture source that could inhibit the crustal relaxation process within "shadow zones" of the Coulomb's failure stress change. Furthermore, the aftershock activity of the 1992 Joshua Tree earthquake (M = 6.1) sharply lowered in the same day of the main shock, which can be explained by a similar scenario.

  14. Lateral and feedforward inhibition suppress asynchronous activity in a large, biophysically-detailed computational model of the striatal network

    PubMed Central

    Moyer, Jason T.; Halterman, Benjamin L.; Finkel, Leif H.; Wolf, John A.

    2014-01-01

    Striatal medium spiny neurons (MSNs) receive lateral inhibitory projections from other MSNs and feedforward inhibitory projections from fast-spiking, parvalbumin-containing striatal interneurons (FSIs). The functional roles of these connections are unknown, and difficult to study in an experimental preparation. We therefore investigated the functionality of both lateral (MSN-MSN) and feedforward (FSI-MSN) inhibition using a large-scale computational model of the striatal network. The model consists of 2744 MSNs comprised of 189 compartments each and 121 FSIs comprised of 148 compartments each, with dendrites explicitly represented and almost all known ionic currents included and strictly constrained by biological data as appropriate. Our analysis of the model indicates that both lateral inhibition and feedforward inhibition function at the population level to limit non-ensemble MSN spiking while preserving ensemble MSN spiking. Specifically, lateral inhibition enables large ensembles of MSNs firing synchronously to strongly suppress non-ensemble MSNs over a short time-scale (10–30 ms). Feedforward inhibition enables FSIs to strongly inhibit weakly activated, non-ensemble MSNs while moderately inhibiting activated ensemble MSNs. Importantly, FSIs appear to more effectively inhibit MSNs when FSIs fire asynchronously. Both types of inhibition would increase the signal-to-noise ratio of responding MSN ensembles and contribute to the formation and dissolution of MSN ensembles in the striatal network. PMID:25505406

  15. Synthesis and photocatalytic activity of stable nanocrystalline TiO(2) with high crystallinity and large surface area.

    PubMed

    Tian, Guohui; Fu, Honggang; Jing, Liqiang; Tian, Chungui

    2009-01-30

    Superior photoactive TiO(2) nanopowders with high crystallinity and large surface area were synthesized by a hydrothermal process in the presence of cetyltrimethylammonium bromide and a post-treatment with ammonia. The prepared photocatalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, N(2) adsorption-desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectra (DRS) and surface photovoltage spectroscopy (SPS). The prepared nanocrystallites were highly resistant to thermal sintering, and the calcinations up to 900 degrees C were shown to enhance the crystallinity of the anatase phase without any rutile phase and the separation rate of photoinduced charges of TiO(2) particles. It remained as large as 196 and 125 m(2)/g even after calcinations at 700 and 800 degrees C, respectively. The photocatalytic activity of prepared photocatalysts was obviously higher than that of commercial Degussa P25 on the photodegradation of methylene blue and phenol in water under ultraviolet-light irradiation, and the sample calcined at 800 degrees C afforded the highest photocatalytic activity.

  16. Restructuring-induced activity of SiO(2)-supported large au nanoparticles in low-temperature CO oxidation.

    PubMed

    Qian, Kun; Sun, Huaxing; Huang, Weixin; Fang, Jun; Lv, Shanshan; He, Bo; Jiang, Zhiquan; Wei, Shiqiang

    2008-01-01

    Large Au nanoparticles with an average size of approximately 10 nm supported on inert SiO(2) become active in low-temperature CO oxidation after the addition of NaNO(3). The catalyst structures have been characterized in detail by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray absorption spectroscopy. The NaNO(3) additive in Au/SiO(2) catalysts does not lead to the formation of fine Au nanoparticles, which are generally considered to be inevitable in low-temperature CO oxidation catalyzed by gold, nor does it alter the electronic structure of Au. The NaNO(3)-induced restructuring of large Au nanoparticles was proposed to create low-coordinated Au sites on the surface capable of catalyzing low-temperature CO oxidation. These results experimentally prove that the activity of supported Au nanoparticles in low-temperature CO oxidation could solely arise from their geometric structure, which greatly deepens the fundamental understandings of Au nanocatalysis.

  17. Enhancement of Polymerase Activity of the Large Fragment in DNA Polymerase I from Geobacillus stearothermophilus by Site-Directed Mutagenesis at the Active Site

    PubMed Central

    Ma, Yi; Zhang, Beilei; Wang, Meng; Ou, Yanghui

    2016-01-01

    The large fragment of DNA polymerase I from Geobacillus stearothermophilus GIM1.543 (Bst DNA polymerase) with 5′-3′ DNA polymerase activity while in absence of 5′-3′ exonuclease activity possesses high thermal stability and polymerase activity. Bst DNA polymerase was employed in isothermal multiple self-matching initiated amplification (IMSA) which amplified the interest sequence with high selectivity and was widely applied in the rapid detection of human epidemic diseases. However, the detailed information of commercial Bst DNA polymerase is unpublished and well protected by patents, which makes the high price of commercial kits. In this study, wild-type Bst DNA polymerase (WT) and substitution mutations for improving the efficiency of DNA polymerization were expressed and purified in E. coli. Site-directed substitutions of four conserved residues (Gly310, Arg412, Lys416, and Asp540) in the activity site of Bst DNA polymerase influenced efficiency of polymerizing dNTPs. The substitution of residue Gly310 by alanine or leucine and residue Asp540 by glutamic acid increased the efficiency of polymerase activity. All mutants with higher polymerizing efficiency were employed to complete the rapid detection of EV71-associated hand, foot, and mouth disease (HFMD) by IMSA approach with relatively shorter period which is suitable for the primary diagnostics setting in rural and underdeveloped areas. PMID:27981047

  18. Activation of large-conductance Ca(2+)-activated K(+) channels inhibits glutamate-induced oxidative stress through attenuating ER stress and mitochondrial dysfunction.

    PubMed

    Yan, Xiao-Hua; Guo, Xiang-Yang; Jiao, Fu-Yong; Liu, Xuan; Liu, Yong

    2015-11-01

    Large-conductance Ca(2+)-activated K(+) channels (BK channels) are widely expressed throughout the vertebrate nervous system, and are involved in the regulation of neurotransmitter release and neuronal excitability. Here, the neuroprotective effects of NS11021, a selective and chemically unrelated BK channel activator, and potential molecular mechanism involved have been studied in rat cortical neurons exposed to glutamate in vitro. Pretreatment with NS11021 significantly inhibited the loss of neuronal viability, LDH release and neuronal apoptosis in a dose-dependent manner. All these protective effects were fully antagonized by the BK-channel inhibitor paxilline. NS11021-induced neuroprotection was associated with reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) generation, lipid peroxidation and preserved activity of antioxidant enzymes. Moreover, NS11021 significantly attenuated the glutamate-induced endoplasmic reticulum (ER) calcium release and activation of ER stress markers, including glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12. Pretreatment with NS11021 also mitigated the mitochondrial membrane potential (MMP) collapse, cytochrome c release, and preserved mitochondrial Ca(2+) buffering capacity and ATP synthesis after glutamate exposure. Taken together, these results suggest that activation of BK channels via NS11021 protects cortical neurons against glutamate-induced excitatory damage, which may be dependent on the inhibition of ER stress and preservation of mitochondrial dysfunction.

  19. Wanderlust kinetics and variable Ca(2+)-sensitivity of Drosophila, a large conductance Ca(2+)-activated K+ channel, expressed in oocytes.

    PubMed Central

    Silberberg, S D; Lagrutta, A; Adelman, J P; Magleby, K L

    1996-01-01

    Cloned large conductance Ca(2+)-activated K+ channels (BK or maxi-K+ channels) from Drosophila (dSlo) were expressed in Xenopus oocytes and studied in excised membrane patches with the patch-clamp technique. Both a natural variant and a mutant that eliminated a putative cyclic AMP-dependent protein kinase phosphorylation site exhibited large, slow fluctuations in open probability with time. These fluctuations, termed "wanderlust kinetics," occurred with a time course of tens of seconds to minutes and had kinetic properties inconsistent with simple gating models. Wanderlust kinetics was still observed in the presence of 5 mM caffeine or 50 nM thapsigargin, or when the Ca2+ buffering capacity of the solution was increased by the addition of 5 mM HEDTA, suggesting that the wanderlust kinetics did not arise from Ca2+ release from caffeine and thapsigargin sensitive internal stores in the excised patch. The slow changes in kinetics associated with wanderlust kinetics could be generated with a discrete-state Markov model with transitions among three or more kinetic modes with different levels of open probability. To average out the wanderlust kinetics, large amounts of data were analyzed and demonstrated up to a threefold difference in the [Ca2+]i required for an open probability of 0.5 among channels expressed from the same injected mRNA. These findings indicate that cloned dSlo channels in excised patches from Xenopus oocytes can exhibit large variability in gating properties, both within a single channel and among channels. PMID:8744301

  20. Preterm human milk contains a large pool of latent TGF-β, which can be activated by exogenous neuraminidase.

    PubMed

    Namachivayam, Kopperuncholan; Blanco, Cynthia L; Frost, Brandy L; Reeves, Aaron A; Jagadeeswaran, Ramasamy; MohanKumar, Krishnan; Safarulla, Azif; Mandal, Partha; Garzon, Steven A; Raj, J Usha; Maheshwari, Akhil

    2013-06-15

    Human milk contains substantial amounts of transforming growth factor (TGF)-β, particularly the isoform TGF-β2. We previously showed in preclinical models that enterally administered TGF-β2 can protect against necrotizing enterocolitis (NEC), an inflammatory bowel necrosis of premature infants. In this study we hypothesized that premature infants remain at higher risk of NEC than full-term infants, even when they receive their own mother's milk, because preterm human milk contains less bioactive TGF-β than full-term milk. Our objective was to compare TGF-β bioactivity in preterm vs. full-term milk and identify factors that activate milk-borne TGF-β. Mothers who delivered between 23 0/7 and 31 6/7 wk or at ≥37 wk of gestation provided milk samples at serial time points. TGF-β bioactivity and NF-κB signaling were measured using specific reporter cells and in murine intestinal tissue explants. TGF-β1, TGF-β2, TGF-β3, and various TGF-β activators were measured by real-time PCR, enzyme immunoassays, or established enzymatic activity assays. Preterm human milk showed minimal TGF-β bioactivity in the native state but contained a large pool of latent TGF-β. TGF-β2 was the predominant isoform of TGF-β in preterm milk. Using a combination of several in vitro and ex vivo models, we show that neuraminidase is a key regulator of TGF-β bioactivity in human milk. Finally, we show that addition of bacterial neuraminidase to preterm human milk increased TGF-β bioactivity. Preterm milk contains large quantities of TGF-β, but most of it is in an inactive state. Addition of neuraminidase can increase TGF-β bioactivity in preterm milk and enhance its anti-inflammatory effects.

  1. Preterm human milk contains a large pool of latent TGF-β, which can be activated by exogenous neuraminidase

    PubMed Central

    Namachivayam, Kopperuncholan; Blanco, Cynthia L.; Frost, Brandy L.; Reeves, Aaron A.; Jagadeeswaran, Ramasamy; MohanKumar, Krishnan; Safarulla, Azif; Mandal, Partha; Garzon, Steven A.; Raj, J. Usha

    2013-01-01

    Human milk contains substantial amounts of transforming growth factor (TGF)-β, particularly the isoform TGF-β2. We previously showed in preclinical models that enterally administered TGF-β2 can protect against necrotizing enterocolitis (NEC), an inflammatory bowel necrosis of premature infants. In this study we hypothesized that premature infants remain at higher risk of NEC than full-term infants, even when they receive their own mother's milk, because preterm human milk contains less bioactive TGF-β than full-term milk. Our objective was to compare TGF-β bioactivity in preterm vs. full-term milk and identify factors that activate milk-borne TGF-β. Mothers who delivered between 23 0/7 and 31 6/7 wk or at ≥37 wk of gestation provided milk samples at serial time points. TGF-β bioactivity and NF-κB signaling were measured using specific reporter cells and in murine intestinal tissue explants. TGF-β1, TGF-β2, TGF-β3, and various TGF-β activators were measured by real-time PCR, enzyme immunoassays, or established enzymatic activity assays. Preterm human milk showed minimal TGF-β bioactivity in the native state but contained a large pool of latent TGF-β. TGF-β2 was the predominant isoform of TGF-β in preterm milk. Using a combination of several in vitro and ex vivo models, we show that neuraminidase is a key regulator of TGF-β bioactivity in human milk. Finally, we show that addition of bacterial neuraminidase to preterm human milk increased TGF-β bioactivity. Preterm milk contains large quantities of TGF-β, but most of it is in an inactive state. Addition of neuraminidase can increase TGF-β bioactivity in preterm milk and enhance its anti-inflammatory effects. PMID:23558011

  2. The internal disruption as hard Magnetohydrodynamic limit of 1/2 sawtooth like activity in large helical device

    SciTech Connect

    Varela, J.; Watanabe, K. Y.; Ohdachi, S.

    2012-08-15

    Large helical device (LHD) inward-shifted configurations are unstable to resistive MHD pressure-gradient-driven modes. Sawtooth like activity was observed during LHD operation. The main drivers are the unstable modes 1/2 and 1/3 in the middle and inner plasma region which limit the plasma confinement efficiency of LHD advanced operation scenarios. The aim of the present research is to study the hard MHD limit of 1/2 sawtooth like activity, not observed yet in LHD operation, and to predict its effects on the device performance. Previous investigations pointed out this system relaxation can be an internal disruption [J. Varela et al., 'Internal disruptions and sawtooth like activity in LHD,' 38th EPS Conference on Plasma Physics (2011), P5.077]. In the present work, we simulate an internal disruption; we study the equilibria properties before and after the disruptive process, its effects on the plasma confinement efficiency during each disruptive phase, the relation between the n/m = 1/2 hard MHD events and the soft MHD events, and how to avoid or reduce their adverse effects. The simulation conclusions point out that the large stochastic region in the middle plasma strongly deforms and tears the flux surfaces when the pressure gradient increases above the hard MHD limit. If the instability reaches the inner plasma, the iota profiles will be perturbed near the plasma core and three magnetic islands can appear near the magnetic axis. If the instability is strong enough to link the stochastic regions in the middle plasma (around the half minor radius {rho}) and the plasma core ({rho}<0.25), an internal disruption is driven.

  3. Inactivation or inhibition of neuronal activity in the medial prefrontal cortex largely reduces pup retrieval and grouping in maternal rats.

    PubMed

    Febo, Marcelo; Felix-Ortiz, Ada C; Johnson, Tehya R

    2010-04-14

    Previous research suggests that the maternal medial prefrontal cortex (mPFC) may play a role in maternal care and that cocaine sensitization before pregnancy can affect neuronal activity within this region. The present work was carried out to test whether the mPFC does actually play a role in the expression of maternal behaviors in the rats and to understand what specific behaviors this cortical area may modulate. In the first experiment, tetrodotoxin (TTX) was used to chemically inactivate the mPFC during tests for maternal behavior latencies. Lactating rats were tested on postpartum days 7-9. The results of this first experiment indicate that there is a large effect of TTX-induced inactivation on retrieval behavior latencies. TTX nearly abolished the expression of maternal retrieval of pups without significantly impairing locomotor activity. In the second experiment, GABA-mediated inhibition was used to test maternal behavior latencies and durations of maternal and other behaviors in postpartum dams. In agreement with experiment 1, it was observed that dams capable of retrieving are rendered incapable by inhibition in the mPFC. GABA-mediated inhibition in the mPFC largely reduced retrieval without altering other indices of maternal care and non-specific behavior such as ambulation time, self-grooming, and inactivity. Moreover, in both experiments, dams were able to establish contact with pups within seconds. The overall results indicate that the mPFC may play an active role in modulating maternal care, particularly retrieval behavior. External factors that affect the function of the frontal cortical site may result in significant impairments in maternal goal-directed behavior as reported in our earlier work. Copyright 2010 Elsevier B.V. All rights reserved.

  4. The internal disruption as hard Magnetohydrodynamic limit of 1/2 sawtooth like activity in large helical device

    NASA Astrophysics Data System (ADS)

    Varela, J.; Watanabe, K. Y.; Ohdachi, S.

    2012-08-01

    Large helical device (LHD) inward-shifted configurations are unstable to resistive MHD pressure-gradient-driven modes. Sawtooth like activity was observed during LHD operation. The main drivers are the unstable modes 1/2 and 1/3 in the middle and inner plasma region which limit the plasma confinement efficiency of LHD advanced operation scenarios. The aim of the present research is to study the hard MHD limit of 1/2 sawtooth like activity, not observed yet in LHD operation, and to predict its effects on the device performance. Previous investigations pointed out this system relaxation can be an internal disruption [J. Varela et al., "Internal disruptions and sawtooth like activity in LHD," 38th EPS Conference on Plasma Physics (2011), P5.077]. In the present work, we simulate an internal disruption; we study the equilibria properties before and after the disruptive process, its effects on the plasma confinement efficiency during each disruptive phase, the relation between the n/m = 1/2 hard MHD events and the soft MHD events, and how to avoid or reduce their adverse effects. The simulation conclusions point out that the large stochastic region in the middle plasma strongly deforms and tears the flux surfaces when the pressure gradient increases above the hard MHD limit. If the instability reaches the inner plasma, the iota profiles will be perturbed near the plasma core and three magnetic islands can appear near the magnetic axis. If the instability is strong enough to link the stochastic regions in the middle plasma (around the half minor radius ρ) and the plasma core (ρ <0.25), an internal disruption is driven.

  5. A Very Large Number of GABAergic Neurons Are Activated in the Tuberal Hypothalamus during Paradoxical (REM) Sleep Hypersomnia

    PubMed Central

    Sapin, Emilie; Bérod, Anne; Léger, Lucienne; Herman, Paul A.; Luppi, Pierre-Hervé; Peyron, Christelle

    2010-01-01

    We recently discovered, using Fos immunostaining, that the tuberal and mammillary hypothalamus contain a massive population of neurons specifically activated during paradoxical sleep (PS) hypersomnia. We further showed that some of the activated neurons of the tuberal hypothalamus express the melanin concentrating hormone (MCH) neuropeptide and that icv injection of MCH induces a strong increase in PS quantity. However, the chemical nature of the majority of the neurons activated during PS had not been characterized. To determine whether these neurons are GABAergic, we combined in situ hybridization of GAD67 mRNA with immunohistochemical detection of Fos in control, PS deprived and PS hypersomniac rats. We found that 74% of the very large population of Fos-labeled neurons located in the tuberal hypothalamus after PS hypersomnia were GAD-positive. We further demonstrated combining MCH immunohistochemistry and GAD67 in situ hybridization that 85% of the MCH neurons were also GAD-positive. Finally, based on the number of Fos-ir/GAD+, Fos-ir/MCH+, and GAD+/MCH+ double-labeled neurons counted from three sets of double-staining, we uncovered that around 80% of the large number of the Fos-ir/GAD+ neurons located in the tuberal hypothalamus after PS hypersomnia do not contain MCH. Based on these and previous results, we propose that the non-MCH Fos/GABAergic neuronal population could be involved in PS induction and maintenance while the Fos/MCH/GABAergic neurons could be involved in the homeostatic regulation of PS. Further investigations will be needed to corroborate this original hypothesis. PMID:20668680

  6. Active stall control for large offshore horizontal axis wind turbines; a conceptual study considering different actuation methods

    NASA Astrophysics Data System (ADS)

    Pereira, R.; van Bussel, G. J. W.; Timmer, W. A.

    2014-12-01

    The increasing size of Horizontal Axis Wind Turbines and the trend to install wind farms further offshore demand more robust design options. If the pitch system could be eliminated, the availability of Horizontal Axis Wind Turbines should increase. This research investigates the use of active stall control to regulate power production in replacement of the pitch system. A feasibility study is conducted using a blade element momentum code and taking the National Renewable Energy Laboratory 5 MW turbine as baseline case. Considering half of the blade span is equipped with actuators, the required change in the lift coefficient to regulate power was estimated in ΔCl = 0.7. Three actuation technologies are investigated, namely Boundary Layer Transpiration, Trailing Edge Jets and Dielectric Barrier Discharge actuators. Results indicate the authority of the actuators considered is not sufficient to regulate power, since the change in the lift coefficient is not large enough. Active stall control of Horizontal Axis Wind Turbines appears feasible only if the rotor is re-designed from the start to incorporate active-stall devices.

  7. Nicotine addiction reduces the large-conductance Ca(2+)-activated potassium channels expression in the nucleus accumbens.

    PubMed

    Ma, Lan; Wu, Yu-Mei; Guo, Yan-Yan; Yang, Qi; Feng, Bin; Song, Qian; Liu, Shui-Bing; Zhao, Da-Qing; Zhao, Ming-Gao

    2013-06-01

    Large-conductance Ca(2+)-activated K(+) channels (BKCa) are widely expressed in the central nervous system and play important roles in neural activities. Nicotine exposure leads to long-lasting changes in behavioral and neuronal plasticity. However, little is known the roles of BKCa in the development of nicotine addiction. In the present study, a significant reduction in BKCa channel expression was found in nucleus accumbens (NAc) from nicotine addiction mice. Whole-cell patch-clamp recordings from NAc neurons of the addicted animals revealed a pronounced reduction in the fast after-hyperpolarization of action potentials mediated by BKCa channels that led to hyperexcitability of the NAc neurons. Activation of BKCa channels in the NAc reversed drug-seeking behaviors which were detected by conditioned place preference test. Furthermore, knockdown of BKCa channels using short hairpin RNAs significantly increased the drug-seeking behavior. These findings provide direct evidence that alterations of BKCa channels in the NAc play critical roles in the development of nicotine addiction and that modulation of the BKCa channels may be potential therapeutics for drug addiction.

  8. The unique N terminus of the herpes simplex virus type 1 large subunit is not required for ribonucleotide reductase activity.

    PubMed

    Conner, J; Macfarlane, J; Lankinen, H; Marsden, H

    1992-01-01

    Using purified bacterially expressed herpes simplex virus type 1 ribonucleotide reductase large subunit (R1) and the proteolytic enzymes chymotrypsin and trypsin, we have generated stable N-terminal truncations. Chymotrypsin removes 246 amino acids from the amino terminus to produce a fragment (dN246R1) which retains full enzymic activity and affinity for the small subunit (R2). Treatment of R1 with trypsin produces a 120K protein and a cleavage at amino acid residue 305 to produce a fragment (dN305R1) which remains associated with a 33K N-terminal polypeptide. Although this 33K-dN305R1 complex retains full binding affinity for R2 its reductase activity is reduced by approximately 50%. Increasing the concentration of trypsin removes the 33K N-terminal polypeptide resulting in dN305R1 which, when bound to R2, has full ribonucleotide reductase activity. Like R1, dN246R1 and dN305R1 each exist as dimers showing that the first 305 amino acids of R1 are not necessary for dimer formation. These results indicate that, in structural studies of subunit interaction, dN246R1 or dN305R1 can be considered as suitable replacements for intact R1.

  9. CO2 biofixation and carbonic anhydrase activity in Scenedesmus obliquus SA1 cultivated in large scale open system.

    PubMed

    Basu, Samarpita; Roy, Abhijit Sarma; Mohanty, Kaustubha; Ghoshal, Aloke K

    2014-07-01

    The present study deals with the large scale open system cultivation of the novel microalga: Scenedesmus obliquus SA1 (KC733762) previously isolated in our laboratory. SA1 strain was cultivated in open system at varying CO2 levels ranging from 0.03% to 35% (v/v) and subsequently the carbonic anhydrase activity (CA) and the biochemical properties were monitored. Maximum biomass concentration (1.39 ± 0.023 g L(-1)), CO2 fixation rate (97.65 ± 1.03 mg L(-1)d(-1)) and total CA activity (166.86 ± 3.30 E.U./mg chla) were obtained at 35% CO2. CA inhibitors: acetazolamide and ethoxyzolamide inhibited the external and internal enzyme activity in SA1. High CO2 levels were favorable for the accumulation of lipids and chlorophyll. The present results suggested that SA1 possessed high CO2 tolerance and high carbohydrate, lipid and chlorophyll content when cultivated in open system thus being suitable for CO2 mitigation in outdoor ponds and subsequent generation of value added products. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Seasonal variation in energy expenditure is not related to activity level or water temperature in a large diving bird.

    PubMed

    Guillemette, Magella; Butler, Patrick J

    2012-09-15

    There is considerable interest in understanding how the energy budget of an endotherm is modulated from a physiological and ecological point of view. In this paper, we used daily (24 h) heart rate (f(H24)), as a proxy of daily energy expenditure (DEE) across seasons, to test the effect of locomotion activity and water temperature on the energy budget of a large diving bird. f(H24) was monitored continuously in common eiders (Somateria mollissima) during 7 months together with measures of time spent flying and time spent feeding. f(H24) varied substantially during the recording period, with numerous increases and decreases that occurred across seasons, although we did not find any relationship between f(H24) and the time spent active (feeding and flying). However, inactive heart rate (f(H,inactive)) decreased as locomotion activity increased, suggesting that common eiders were using some form of compensation when under a high work load. We were also unable to detect a negative relationship between water temperature and resting heart rate, a proxy of resting metabolic rate. This was unexpected, based on the assumption that high thermoregulation costs would be associated with cold waters. We showed instead that a high level of energy expenditure coincided with feather moult and warm waters, which suggests that the observed variable pattern of seasonal DEE was driven by these two factors. Nevertheless, our results indicate that compensation and possibly the timing of moult may be used as mechanisms to reduce seasonal variation in energy expenditure.

  11. The development of a fiber optics communication network for controlling a Multidegree-Of-Freedom Serpentine Truss

    NASA Technical Reports Server (NTRS)

    Andrawis, Alfred S.

    1994-01-01

    The problem addressed by this report is the large size and heavy weight of the cable bundle, used for controlling a Multidegree-Of-Freedom Serpentine Truss Manipulator arm, which imposes limitations on the manipulator arm maneuverability. This report covers a design of an optical fiber network to replace the existing copper wire network of the Serpentine Truss Manipulator. This report proposes a fiber network design which significantly reduces the bundle size into two phases. The first phase does not require any modifications for the manipulator architecture, while the other requires major modifications. Design philosophy, hardware details and schematic diagrams are presented.

  12. Inhibition of Ca2+-activated large-conductance K+ channel activity alters synaptic AMPA receptor phenotype in mouse cerebellar stellate cells.

    PubMed

    Liu, Yu; Savtchouk, Iaroslav; Acharjee, Shoana; Liu, Siqiong June

    2011-07-01

    Many fast-spiking inhibitory interneurons, including cerebellar stellate cells, fire brief action potentials and express α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors (AMPAR) that are permeable to Ca(2+) and do not contain the GluR2 subunit. In a recent study, we found that increasing action potential duration promotes GluR2 gene transcription in stellate cells. We have now tested the prediction that activation of potassium channels that control the duration of action potentials can suppress the expression of GluR2-containing AMPARs at stellate cell synapses. We find that large-conductance Ca(2+)-activated potassium (BK) channels mediate a large proportion of the depolarization-evoked noninactivating potassium current in stellate cells. Pharmacological blockade of BK channels prolonged the action potential duration in postsynaptic stellate cells and altered synaptic AMPAR subtype from GluR2-lacking to GluR2-containing Ca(2+)-impermeable AMPARs. An L-type channel blocker abolished an increase in Ca(2+) entry that was associated with spike broadening and also prevented the BK channel blocker-induced switch in AMPAR phenotype. Thus blocking BK potassium channels prolongs the action potential duration and increases the expression of GluR2-containing receptors at the synapse by enhancing Ca(2+) entry in cerebellar stellate cells.

  13. Inhibition of Ca2+-activated large-conductance K+ channel activity alters synaptic AMPA receptor phenotype in mouse cerebellar stellate cells

    PubMed Central

    Liu, Yu; Savtchouk, Iaroslav; Acharjee, Shoana

    2011-01-01

    Many fast-spiking inhibitory interneurons, including cerebellar stellate cells, fire brief action potentials and express α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors (AMPAR) that are permeable to Ca2+ and do not contain the GluR2 subunit. In a recent study, we found that increasing action potential duration promotes GluR2 gene transcription in stellate cells. We have now tested the prediction that activation of potassium channels that control the duration of action potentials can suppress the expression of GluR2-containing AMPARs at stellate cell synapses. We find that large-conductance Ca2+-activated potassium (BK) channels mediate a large proportion of the depolarization-evoked noninactivating potassium current in stellate cells. Pharmacological blockade of BK channels prolonged the action potential duration in postsynaptic stellate cells and altered synaptic AMPAR subtype from GluR2-lacking to GluR2-containing Ca2+-impermeable AMPARs. An L-type channel blocker abolished an increase in Ca2+ entry that was associated with spike broadening and also prevented the BK channel blocker-induced switch in AMPAR phenotype. Thus blocking BK potassium channels prolongs the action potential duration and increases the expression of GluR2-containing receptors at the synapse by enhancing Ca2+ entry in cerebellar stellate cells. PMID:21562198

  14. Using active learning strategies to investigate student learning and attitudes in a large enrollment, introductory geology course

    NASA Astrophysics Data System (ADS)

    Berry, Stacy Jane

    There has been an increased emphasis for college instruction to incorporate more active and collaborative involvement of students in the learning process. These views have been asserted by The Association of American Colleges (AAC), the National Science Foundation (NSF), and The National Research Counsel (NRC), which are advocating for the modification of traditional instructional techniques to allow students the opportunity to be more cooperative (Task Group on General Education, 1988). This has guided educators and facilitators into shifting teaching paradigms from a teacher centered to a more student-centered curriculum. The present study investigated achievement outcomes and attitudes of learners in a large enrollment (n ~ 200), introductory geology course using a student centered learning cycle format of instruction versus another similar section that used a traditional lecture format. Although the course is a recruiting class for majors, over 95% of the students that enroll are non-majors. Measurements of academic evaluation were through four unit exams, classroom communication systems, weekly web-based homework, in-class activities, and a thematic collaborative poster/paper project and presentation. The qualitative methods to investigate the effectiveness of the teaching design included: direct observation, self-reporting about learning, and open-ended interviews. By disaggregating emerging data, we tried to concentrate on patterns and causal relationships between achievement performance and attitudes regarding learning geology. Statistical analyses revealed positive relationships between student engagement in supplemental activities and achievement mean scores within and between the two sections. Completing weekly online homework had the most robust relationship with overall achievement performance. Contrary to expectations, a thematic group project only led to modest gains in achievement performance, although the social and professional gains could be

  15. Integrating pre-, in- and post-lecture activities to improve students' learning in a large introductory physics course

    NASA Astrophysics Data System (ADS)

    Cheng, Kwan; Caglar, Mehmet; Pietan, Amy; Dulli, Hani

    2011-03-01

    Monitoring and assessing the students' learning activities before, during and after lecture teaching in a large (more than 150 students) introductory physics class setting are important to evaluate the efficacies of various teaching pedagogies and methods. At Texas Tech, an online and integrative computer-based approach of using an interactive pre-lecture tutorial, an in-class concept test using a wireless student response system and a homework/tutorial system has been implemented in Fall 2010. The strategy of implementation of this integrative approach and the assessment results from various in-house and standard Mechanics tests will be presented. In addition, how this approach may create synergism of lab and lecture teaching efforts will also be addressed. This project is supported by the NIH grant 5RC1GM090897-02.

  16. Detection of triazole deicing additives in soil samples from airports with low, mid, and large volume aircraft deicing activities.

    PubMed

    McNeill, K S; Cancilla, D A

    2009-03-01

    Soil samples from three USA airports representing low, mid, and large volume users of aircraft deicing fluids (ADAFs) were analyzed by LC/MS/MS for the presence of triazoles, a class of corrosion inhibitors historically used in ADAFs. Triazoles, specifically the 4-methyl-1H-benzotriazole and the 5-methyl-1H-benzotriazole, were detected in a majority of samples and ranged from 2.35 to 424.19 microg/kg. Previous studies have focused primarily on ground and surface water impacts of larger volume ADAF users. The detection of triazoles in soils at low volume ADAF use airports suggests that deicing activities may have a broader environmental impact than previously considered.

  17. FDG Uptake by Prosthetic Arterial Grafts in Large Vessel Vasculitis Is Not Specific for Active Disease.

    PubMed

    Youngstein, Taryn; Tombetti, Enrico; Mukherjee, Jaita; Barwick, Tara D; Al-Nahhas, Adil; Humphreys, Emyr; Nash, Julian; Andrews, Jacqueline; Incerti, Elena; Tombolini, Elisabetta; Salerno, Annalaura; Sartorelli, Silvia; Ramirez, Giuseppe A; Papa, Maurizio; Sabbadini, Maria Grazia; Gianolli, Luigi; De Cobelli, Francesco; Fallanca, Federico; Baldissera, Elena; Manfredi, Angelo A; Picchio, Maria; Mason, Justin C

    2017-09-01

    This study investigated the incidence and clinical significance of arterial graft-associated uptake of fluorodeoxyglucose in large-vessel vasculitis (LVV). The role of (18)F-labeled fluorodeoxyglucose-positron emission tomography/computed tomography ([(18)F]FDG-PET/CT) in the management of LVV remains to be defined. Although [(18)F]FDG uptake at arterial graft sites raises concerns regarding active arteritis or infection, its clinical significance in LVV has never been formally studied. An observational prospective study sought to identify patients with Takayasu arteritis (TA) undergoing [(18)F]FDG-PET/CT more than 6 months after graft surgery from a large cohort of patients from 2 tertiary referral centers. [(18)F]FDG uptake by the graft and native arteries was scored on a scale of 0 to 3 relative to hepatic uptake, and periprosthetic maximum standardized uptake value (SUVmax) was calculated. Periprosthetic [(18)F]FDG uptake in active disease was compared with that in inactive disease, and arterial progression was assessed by prospective magnetic resonance angiography (MRA). Twenty-six subjects with TA were enrolled. All were afebrile with negative blood culture. Periprosthetic uptake was significant in 23 of 26 patients, and the mean SUVmax was 4.21 ± 1.46. Median periprosthetic [(18)F]FDG uptake score (3; interquartile range [IQR]: 3 to 3) was higher than in native aorta (1; IQR: 0 to 1; p < 0.001). Graft-specific [(18)F]FDG uptake was unrelated to disease activity. Despite the high frequency of graft-associated [(18)F]FDG uptake, sequential MRAs did not reveal arterial progression in 25 of 26 patients; the 1 remaining case showed minor progression limited to native arteries. Nine patients underwent repeated PET/CT scanning without showing changes in graft-specific uptake, despite increased treatment. Significant [(18)F]FDG uptake that is confined to arterial graft sites in patients with LVV does not reflect clinically relevant disease activity or

  18. RNA-seq pinpoints a Xanthomonas TAL-effector activated resistance gene in a large-crop genome.

    PubMed

    Strauss, Tina; van Poecke, Remco M P; Strauss, Annett; Römer, Patrick; Minsavage, Gerald V; Singh, Sylvia; Wolf, Christina; Strauss, Axel; Kim, Seungill; Lee, Hyun-Ah; Yeom, Seon-In; Parniske, Martin; Stall, Robert E; Jones, Jeffrey B; Choi, Doil; Prins, Marcel; Lahaye, Thomas

    2012-11-20

    Transcription activator-like effector (TALE) proteins of the plant pathogenic bacterial genus Xanthomonas bind to and transcriptionally activate host susceptibility genes, promoting disease. Plant immune systems have taken advantage of this mechanism by evolving TALE binding sites upstream of resistance (R) genes. For example, the pepper Bs3 and rice Xa27 genes are hypersensitive reaction plant R genes that are transcriptionally activated by corresponding TALEs. Both R genes have a hallmark expression pattern in which their transcripts are detectabl