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. 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. PMID:21503070

  3. 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.

  4. Large Numbers and Calculators: A Classroom Activity.

    ERIC Educational Resources Information Center

    Arcavi, Abraham; Hadas, Nurit

    1989-01-01

    Described is an activity demonstrating how a scientific calculator can be used in a mathematics classroom to introduce new content while studying a conventional topic. Examples of reading and writing large numbers, and reading hidden results are provided. (YP)

  5. 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.

  6. Bipolar spinal cord stimulation attenuates mechanical hypersensitivity at an intensity that activates a small portion of A-fiber afferents in spinal nerve-injured rats.

    PubMed

    Yang, F; Carteret, A F; Wacnik, P W; Chung, C-Y; Xing, L; Dong, X; Meyer, R A; Raja, S N; Guan, Y

    2011-12-29

    Spinal cord stimulation (SCS) is used clinically to treat neuropathic pain states, but the precise mechanism by which it attenuates neuropathic pain remains to be established. The profile of afferent fiber activation during SCS and how it may correlate with the efficacy of SCS-induced analgesia are unclear. After subjecting rats to an L5 spinal nerve ligation (SNL), we implanted a miniature quadripolar electrode similar to that used clinically. Our goal was to determine the population and number of afferent fibers retrogradely activated by SCS in SNL rats by recording the antidromic compound action potential (AP) at the sciatic nerve after examining the ability of bipolar epidural SCS to alleviate mechanical hypersensitivity in this model. Notably, we compared the profiles of afferent fiber activation to SCS between SNL rats that exhibited good SCS-induced analgesia (responders) and those that did not (nonresponders). Additionally, we examined how different contact configurations affect the motor threshold (MoT) and compound AP threshold. Results showed that three consecutive days of SCS treatment (50 Hz, 0.2 ms, 30 min, 80-90% of MoT), but not sham stimulation, gradually alleviated mechanical hypersensitivity in SNL rats. The MoT obtained in the animal behavioral study was significantly less than the Aα/β-threshold of the compound AP determined during electrophysiological recording, suggesting that SCS could attenuate mechanical hypersensitivity with a stimulus intensity that recruits only a small fraction of the A-fiber population in SNL rats. Although both the MoT and compound AP threshold were similar between responders and nonresponders, the size of the compound AP waveform at higher stimulation intensities was larger in the responders, indicating a more efficient activation of the dorsal column structure in responders. PMID:22001681

  7. Large-scale recording of astrocyte activity

    PubMed Central

    Nimmerjahn, Axel; Bergles, Dwight E.

    2015-01-01

    Astrocytes are highly ramified glial cells found throughout the central nervous system (CNS). They express a variety of neurotransmitter receptors that can induce widespread chemical excitation, placing these cells in an optimal position to exert global effects on brain physiology. However, the activity patterns of only a small fraction of astrocytes have been examined and techniques to manipulate their behavior are limited. As a result, little is known about how astrocytes modulate CNS function on synaptic, microcircuit, or systems levels. Here, we review current and emerging approaches for visualizing and manipulating astrocyte activity in vivo. Deciphering how astrocyte network activity is controlled in different physiological and pathological contexts is critical for defining their roles in the healthy and diseased CNS. PMID:25665733

  8. 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…

  9. 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...

  10. Implementing Small-Group Activities in Large Lecture Classes

    ERIC Educational Resources Information Center

    Yazedjian, Ani; Kolkhorst, Brittany Boyle

    2007-01-01

    This study examines student perceptions regarding the effectiveness of small-group work in a large lecture class. The article considers and illustrates from students' perspectives the ways in which small-group activities could enhance comprehension of course material, reduce anonymity associated with large lecture classes, and promote student…

  11. 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

  12. Large scale organization of rat sensorimotor cortex based on a motif of large activation spreads

    PubMed Central

    Frostig, Ron D.; Xiong, Ying; Chen-Bee, Cynthia H.; Kvašňák, Eugen; Stehberg, Jimmy

    2008-01-01

    Parcellation according to function (e.g., visual, somatosensory, auditory, motor) is considered a fundamental property of sensorimotor cortical organization, traditionally defined from cytoarchitectonics and mapping studies relying on peak evoked neuronal activity. In the adult rat, stimulation of single whiskers evokes peak activity at topographically appropriate locations within somatosensory cortex and provides an example of cortical functional specificity. Here, we show that single whisker stimulation also evokes symmetrical areas of supra- and sub-threshold neuronal activation that spread extensively away from peak activity, effectively ignoring cortical borders by spilling deeply into multiple cortical territories of different modalities (auditory, visual and motor), where they were blocked by localized neuronal activity blocker injections and thus ruled out as possibly due to ‘volume conductance’. These symmetrical activity spreads were supported by underlying border-crossing, long-range horizontal connections as confirmed with transection experiments and injections of anterograde neuronal tracer experiments. We found such large evoked activation spreads and their underlying connections irrespective of whisker identity, cortical layer, or axis of recorded responses, thereby revealing a large scale nonspecific organization of sensorimotor cortex based on a motif of large symmetrical activation spreads. Because the large activation spreads and their underlying horizontal connections ignore anatomical borders between cortical modalities, sensorimotor cortex could therefore be viewed as a continuous entity rather than a collection of discrete, delineated unimodal regions – an organization that could co-exist with established specificity of cortical organization and that could serve as a substrate for associative learning, direct multimodal integration and recovery of function following injury. PMID:19052219

  13. 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.

  14. 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

  15. Large-aperture active optical carbon fiber reinforced polymer mirror

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew E. L.; Wilcox, Christopher C.; Wick, David V.; Baker, Michael S.; Hobart, Clinton G.; Milinazzo, Jared J.; Robichaud, Joseph; Romeo, Robert C.; Martin, Robert N.; Ballesta, Jerome; Lavergne, Emeric; Dereniak, Eustace L.

    2013-05-01

    An active reflective component can change its focal length by physically deforming its reflecting surface. Such elements exist at small apertures, but have yet to be fully realized at larger apertures. This paper presents the design and initial results of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  16. 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.

  17. How Large Scales Flows May Influence Solar Activity

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.

    2004-01-01

    Large scale flows within the solar convection zone are the primary drivers of the Sun's magnetic activity cycle and play important roles in shaping the Sun's magnetic field. Differential rotation amplifies the magnetic field through its shearing action and converts poloidal field into toroidal field. Poleward meridional flow near the surface carries magnetic flux that reverses the magnetic poles at about the time of solar maximum. The deeper, equatorward meridional flow can carry magnetic flux back toward the lower latitudes where it erupts through the surface to form tilted active regions that convert toroidal fields into oppositely directed poloidal fields. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun's rotation on convection produce velocity correlations that can maintain both the differential rotation and the meridional circulation. These convective motions can also influence solar activity directly by shaping the magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

  18. 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

  19. Active Exploration of Large 3D Model Repositories.

    PubMed

    Gao, Lin; Cao, Yan-Pei; Lai, Yu-Kun; Huang, Hao-Zhi; Kobbelt, Leif; Hu, Shi-Min

    2015-12-01

    With broader availability of large-scale 3D model repositories, the need for efficient and effective exploration becomes more and more urgent. Existing model retrieval techniques do not scale well with the size of the database since often a large number of very similar objects are returned for a query, and the possibilities to refine the search are quite limited. We propose an interactive approach where the user feeds an active learning procedure by labeling either entire models or parts of them as "like" or "dislike" such that the system can automatically update an active set of recommended models. To provide an intuitive user interface, candidate models are presented based on their estimated relevance for the current query. From the methodological point of view, our main contribution is to exploit not only the similarity between a query and the database models but also the similarities among the database models themselves. We achieve this by an offline pre-processing stage, where global and local shape descriptors are computed for each model and a sparse distance metric is derived that can be evaluated efficiently even for very large databases. We demonstrate the effectiveness of our method by interactively exploring a repository containing over 100 K models. PMID:26529460

  20. Radio Coronal Magnetography of a Large Active Region

    NASA Astrophysics Data System (ADS)

    Bastian, Timothy S.; Gary, Dale E.; White, Stephen; Fleishman, Gregory; Chen, Bin

    2015-04-01

    Quantitative knowledge of coronal magnetic fields is fundamental to understanding energetic phenomena such as solar flares. Flares occur in solar active regions where strong, non-potential magnetic fields provide free energy. While constraints on the coronal magnetic field topology are readily available through high resolution SXR and EUV imaging of solar active regions, useful quantitative measurements of coronal magnetic fields have thus far been elusive. Recent progress has been made at infrared (IR) wavelengths in exploiting both the Zeeman and Hanle effects to infer the line-of-sight magnetic field strength or the orientation of the magnetic field vector in the plane of the sky above the solar limb. However, no measurements of coronal magnetic fields against the solar disk are possible using IR observations. Radio observations of gyroresonance emission from active regions offer the means of measuring coronal magnetic fields above the limb and on the solar disk. In particular, for plasma plasma conditions in the solar corona, active regions typically become optically thick to emission over a range of radio frequencies through gyroresonance absorption at a low harmonic of the electron gyrofrequency. The specific range of resonant frequencies depends on the range of coronal magnetic field strengths present in the active region.The Karl G. Jansky Very Large Array was used in November 2014 to image NOAA/USAF active region AR12209 over a continuous frequency range of 1-8 GHz, corresponding to a wavelength range of 3.75-30 cm. This frequency range is sensitive to coronal magnetic field strengths ranging from ~120-1400G. The active region was observed on four different dates - November 18, 20, 22, and 24 - during which the active region longitude ranged from -15 to +70 degrees, providing a wide range of aspect angles. In this paper we provide a preliminary description of the coronal magnetic field measurements derived from the radio observations.

  1. Technologies for imaging neural activity in large volumes.

    PubMed

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

    2016-08-26

    Neural circuitry has evolved to form distributed networks that act dynamically across large volumes. Conventional microscopy collects data from individual planes and 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 processing and analyzing volume imaging data of increasing size and complexity. Together, optical and computational advances are providing a broader view of neural circuit dynamics and helping elucidate how brain regions work in concert to support behavior. PMID:27571194

  2. 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.

  3. Activation of large ions in FT-ICR mass spectrometry.

    PubMed

    Laskin, Julia; Futrell, Jean H

    2005-01-01

    The advent of soft ionization techniques, notably electrospray and laser desorption ionization methods, has enabled the extension of mass spectrometric methods to large molecules and molecular complexes. This both greatly extends the applications of mass spectrometry and makes the activation and dissociation of complex ions an integral part of these applications. This review emphasizes the most promising methods for activation and dissociation of complex ions and presents this discussion in the context of general knowledge of reaction kinetics and dynamics largely established for small ions. We then introduce the characteristic differences associated with the higher number of internal degrees of freedom and high density of states associated with molecular complexity. This is reflected primarily in the kinetics of unimolecular dissociation of complex ions, particularly their slow decay and the higher energy content required to induce decomposition--the kinetic shift (KS). The longer trapping time of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) significantly reduces the KS, which presents several advantages over other methods for the investigation of dissociation of complex molecules. After discussing general principles of reaction dynamics related to collisional activation of ions, we describe conventional ways to achieve single- and multiple-collision activation in FT-ICR MS. Sustained off-resonance irradiation (SORI)--the simplest and most robust means of introducing the multiple collision activation process--is discussed in greatest detail. Details of implementation of this technique, required control of experimental parameters, limitations, and examples of very successful application of SORI-CID are described. The advantages of high mass resolving power and the ability to carry out several stages of mass selection and activation intrinsic to FT-ICR MS are demonstrated in several examples. Photodissociation of ions from small molecules

  4. 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

  5. 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.

  6. 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

  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. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  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. 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.

  12. 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.…

  13. 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

  14. Active versus passive damping in large flexible structures

    NASA Technical Reports Server (NTRS)

    Slater, Gary L.; Mclaren, Mark D.

    1991-01-01

    Optimal passive and active damping control can be considered in the context of a general control/structure optimization problem. Using a mean square output response approach, it is shown that the weight sensitivity of the active and passive controllers can be used to determine an optimal mix of active and passive elements in a flexible structure.

  15. 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.

  16. 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.

  17. 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.

  18. 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…

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:26701656

  7. 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.

  8. 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.

  9. Biomedical probe using a fiber-optic coupled scintillator.

    PubMed

    Swinth, K L; Ewins, J H

    1976-01-01

    A high-sensitivity biomedical radiation probe which employs a fiber-optic coupled NaI(Tl) scintillator as a detector is described. It was developed for in vivo counting of low-energy 239Pu photons from material located in the tracheobronchial lymph nodes.-This probe is 20 times as sensitive as a solid-state probe (avalanche diode) previously developed for this application. Tests with 99mTc show a sensitivity more than 90 times greater than biomedical probes using DcTe of GaAs; however, the improved sensitivity is largely due to an increased sensitive volume. Probes were evaluated in animals and phantoms for detection of 239Pu and for location of lung tumors labeled with 111In. PMID:1264039

  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. 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…

  12. How Large Scale Flows in the Solar Convection Zone may Influence Solar Activity

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.

    2004-01-01

    Large scale flows within the solar convection zone are the primary drivers of the Sun s magnetic activity cycle. Differential rotation can amplify the magnetic field and convert poloidal fields into toroidal fields. Poleward meridional flow near the surface can carry magnetic flux that reverses the magnetic poles and can convert toroidal fields into poloidal fields. The deeper, equatorward meridional flow can carry magnetic flux toward the equator where it can reconnect with oppositely directed fields in the other hemisphere. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun s rotation on convection produce velocity correlations that can maintain the differential rotation and meridional circulation. These convective motions can influence solar activity themselves by shaping the large-scale magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

  13. Actors of the main activity in large complex centres during the 23 solar cycle maximum

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Démoulin, P.; Pariat, E.; Török, T.; Molodij, G.; Mandrini, C. H.; Dasso, S.; Chandra, R.; Uddin, W.; Kumar, P.; Manoharan, P. K.; Venkatakrishnan, P.; Srivastava, N.

    2011-06-01

    During the maximum of Solar Cycle 23, large active regions had a long life, spanning several solar rotations, and produced large numbers of X-class flares and CMEs, some of them associated to magnetic clouds (MCs). This is the case for the Halloween active regions in 2003. The most geoeffective MC of the cycle (Dst = -457) had its source during the disk passage of one of these active regions (NOAA 10501) on 18 November 2003. Such an activity was presumably due to continuous emerging magnetic flux that was observed during this passage. Moreover, the region exhibited a complex topology with multiple domains of different magnetic helicities. The complexity was observed to reach such unprecedented levels that a detailed multi-wavelength analysis is necessary to precisely identify the solar sources of CMEs and MCs. Magnetic clouds are identified using in situ measurements and interplanetary scintillation (IPS) data. Results from these two different sets of data are also compared.

  14. 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.

  15. 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…

  16. 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…

  17. 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,…

  18. 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…

  19. Using Accelerometers to Measure Physical Activity in Large-Scale Epidemiologic Studies: Issues and Challenges

    PubMed Central

    Lee, I-Min; Shiroma, Eric J

    2013-01-01

    Background Current guidelines for aerobic activity require that adults carry out ≥150 minutes/week of moderate-intensity physical activity, with a large body of epidemiologic evidence showing this level of activity to decrease the incidence of many chronic diseases. Less is known about whether light-intensity activities also have such benefits, and whether sedentary behavior is an independent predictor of increased risks of these chronic diseases, as imprecise assessments of these behaviours and cross-sectional study designs have limited knowledge to date. Methods Recent technological advances in assessment methods have made the use of movement sensors, such as the accelerometer, feasible for use in longitudinal, large-scale epidemiologic studies. Several such studies are collecting sensor-assessed, objective measures of physical activity with the aim of relating these to the development of clinical endpoints. This is a relatively new area of research; thus, in this paper, we use the Women’s Health Study (WHS) as a case study to illustrate challenges related to data collection, data processing, and analyses of the vast amount of data collected. Results The WHS plans to collect 7 days of accelerometer-assessed physical activity and sedentary behavior in ~18,000 women aged ≥62 years. Several logistical challenges exist in collecting data; nonetheless as of 31 August 2013, 11,590 women have already provided some data. Additionally, the WHS experience on data reduction and data analyses can help inform other similar large-scale epidemiologic studies. Conclusions Important data on the health effects of light-intensity activity and sedentary behaviour will emerge from large-scale epidemiologic studies collecting objective assessments of these behaviours. PMID:24297837

  20. Activation patterns of embryonic chick lumbosacral motoneurones following large spinal cord reversals.

    PubMed Central

    Vogel, M W

    1987-01-01

    1. Embryonic chick motoneurones were caused to innervate inappropriate hindlimb muscles by rotating the presumptive lumbosacral region of the neural tube in stage 15-16 embryos which is prior to the outgrowth of motoneurone axons. 2. The activation patterns of motoneurones in control and spinal cord reversal embryos were analysed from electromyographic (e.m.g.) recordings of stage 36 limb muscles during evoked movement sequences in an isolated spinal cord-limb preparation. Histograms representing the frequency of activation were constructed for each muscle. The muscle's pattern of activation was classified as flexor-like or extensor-like and compared to the activation patterns of control muscles. 3. A series of control operations was performed in which the prospective lumbosacral region of the neural tube was removed and replaced in its original orientation. Muscles in these embryos were innervated by their normal motoneurone pools and they were activated normally, indicating that the neural tube operation per se does not alter the activation pattern of motoneurones. Furthermore, some muscles (twelve out of sixty-one) in spinal cord reversal embryos had normal activation patterns and appeared to be innervated by their original motoneurones. Based on these results and the result of a previous study (Landmesser & O'Donovan, 1984 b), it is concluded that motoneurones in reversed spinal cords are activated in a manner appropriate for their original identity. 4. The majority of muscles (thirty-three out of sixty-one) in large spinal cord reversal embryos were activated during an appropriate phase of the kicking cycle. Of the remaining muscles, 16% were activated inappropriately (i.e. extensor muscles were activated as flexors, and vice versa), and 30% had a novel 'mixed' flexor- and extensor-like activation pattern. However, the activation pattern of most muscles differed markedly from that of any other control muscles regardless of whether the muscle was activated

  1. 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.

  2. Large-Conductance Calcium-Activated Potassium Channels in Glomerulus: From Cell Signal Integration to Disease

    PubMed Central

    Tao, Jie; Lan, Zhen; Wang, Yunman; Hei, Hongya; Tian, Lulu; Pan, Wanma; Zhang, Xuemei; Peng, Wen

    2016-01-01

    Large-conductance calcium-activated potassium (BK) channels are currently considered as vital players in a variety of renal physiological processes. In podocytes, BK channels become active in response to stimuli that increase local cytosolic Ca2+, possibly secondary to activation of slit diaphragm TRPC6 channels by chemical or mechanical stimuli. Insulin increases filtration barrier permeability through mobilization of BK channels. In mesangial cells, BK channels co-expressed with β1 subunits act as a major component of the counteractive response to contraction in order to regulate glomerular filtration. This review aims to highlight recent discoveries on the localization, physiological and pathological roles of BK channels in glomerulus. PMID:27445840

  3. Large-Conductance Calcium-Activated Potassium Channels in Glomerulus: From Cell Signal Integration to Disease.

    PubMed

    Tao, Jie; Lan, Zhen; Wang, Yunman; Hei, Hongya; Tian, Lulu; Pan, Wanma; Zhang, Xuemei; Peng, Wen

    2016-01-01

    Large-conductance calcium-activated potassium (BK) channels are currently considered as vital players in a variety of renal physiological processes. In podocytes, BK channels become active in response to stimuli that increase local cytosolic Ca(2+), possibly secondary to activation of slit diaphragm TRPC6 channels by chemical or mechanical stimuli. Insulin increases filtration barrier permeability through mobilization of BK channels. In mesangial cells, BK channels co-expressed with β1 subunits act as a major component of the counteractive response to contraction in order to regulate glomerular filtration. This review aims to highlight recent discoveries on the localization, physiological and pathological roles of BK channels in glomerulus. PMID:27445840

  4. Reflector adjustment for a large radio telescope based on active optics

    NASA Astrophysics Data System (ADS)

    Li, Tongying; Zhang, Zhenchao; Li, Aihua; Wang, You

    2012-09-01

    The reflector deformation caused by gravity, temperature, humidity, wind loading and so on can reduce the global performance of a large radio telescope. In this paper, considering the characteristics of the primary reflector of a 13.7 m millimeter-wave telescope a novel reflector adjustment method based on active optics has therefore been proposed to control the active surface of the reflector through the communication between the active surface computer and embedded intelligent controller with a large quantity of displacement actuators, in which the active surface computer estimates and controls the real time active surface figure at any elevation angle, reduces or eliminates the adverse effects of the reflector deformation to increase the resolution and sensitivity of the radio telescope due to the more radio signals collected. A Controller Area Network /Ethernet protocol converter is designed for the communication between the active surface control computer as a host computer in Ethernet and the displacement actuator controller in Controller Area Network. The displacement actuator is driven by a stepper motor and controlled by an intelligent controller with the data from the active surface computer. The closed-loop control of the stepper motor improves the control accuracy greatly through the feedback link based on the optical encoder.

  5. 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

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

    PubMed

    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.

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

    PubMed

    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

  8. 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

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

    PubMed Central

    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

    2009-01-01

    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. PMID:19897720

  10. 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

  11. Targeting Large Kinase Active Site with Rigid, Bulky Octahedral Ruthenium Complexes

    SciTech Connect

    Maksimoska, Jasna; Feng, Li; Harms, Klaus; Yi, Chunling; Kissil, Joseph; Marmorstein, Ronen; Meggers, Eric

    2009-09-02

    A strategy for targeting protein kinases with large ATP-binding sites by using bulky and rigid octahedral ruthenium complexes as structural scaffolds is presented. A highly potent and selective GSK3 and Pim1 half-sandwich complex NP309 was successfully converted into a PAK1 inhibitor by making use of the large octahedral compounds {Lambda}-FL172 and {Lambda}-FL411 in which the cyclopentadienyl moiety of NP309 is replaced by a chloride and sterically demanding diimine ligands. A 1.65 {angstrom}cocrystal structure of PAK1 with {Lambda}-FL172 reveals how the large coordination sphere of the ruthenium complex matches the size of the active site and serves as a yardstick to discriminate between otherwise closely related binding sites.

  12. Design issues for the active control system of the California Extremely Large Telescope (CELT)

    NASA Astrophysics Data System (ADS)

    Chanan, Gary A.; Nelson, Jerry E.; Ohara, Catherine M.; Sirko, Edwin

    2000-08-01

    We explore the issues in the control and alignment of the primary mirror of the proposed 30 meter California Extremely Large Telescope and other very large telescopes with segmented primaries (consisting of 1000 or more segments). We show that as the number of segments increases, the noise in the telescope active control system (ACS) increases, roughly as (root)n. This likely means that, for a thousand segment telescope like CELT, Keck-style capacitive sensors will not be able to adequately monitor the lowest spatial frequency degrees of freedom of the primary mirror, and will therefore have to be supplemented by a Shack-Hartmann-type wavefront sensor. However, in the case of segment phasing, which is governed by a `control matrix' similar to that of the ACS, the corresponding noise is virtually independent of n. It follows that reasonably straightforward extensions of current techniques should be adequate to phase the extremely large telescopes of the future.

  13. Logistical aspects of large telemedicine networks. 2: Measurement of network activity.

    PubMed

    Wootton, Richard; Smith, Anthony C; Gormley, Sinead; Patterson, Jessica

    2002-01-01

    We carried out a retrospective review of the videoconference activity records in a university-run hospital telemedicine studio. Usage records describing videoconferencing activity in the telemedicine studio were compared with the billing records provided by the telecommunications company. During a seven-month period there were 211 entries in the studio log: 108 calls made from the studio and 103 calls made from a far-end location. We found that 103 calls from a total of 195 calls reported by the telecommunications company were recorded in the usage log. The remaining 92 calls were not recorded, probably for one of several reasons, including: failed calls--a large number of unrecorded calls (57%) lasted for less than 2 min (median 1.6 min); origin of videoconference calls--calls may have been recorded incorrectly in the usage diary (i.e. as being initiated from the far end, when actually initiated from the studio); and human error. Our study showed that manual recording of videoconference activity may not accurately reflect the actual activity taking place. Those responsible for recording and analysing videoconference activity, particularly in large telemedicine networks, should do so with care.

  14. Photospheric, Chromospheric and Helioseismic Signatures of a Large Flare in Super-active Region NOAA 10486

    NASA Astrophysics Data System (ADS)

    Ambastha, Ashok

    2006-09-01

    NOAA 10486 produced several powerful flares, including the 4B/X17.2 superflare of October 28, 2003/11:10 UT. This flare was extensively covered by the Hα and GONG instruments operated at the Udaipur Solar Observatory (USO). The central location of the active region on October 28, 2003 was well-suited for the ring diagram analysis to obtain the 3-D power spectra and search for helioseismic response of this large flare on the amplitude, frequency and width of the p-modes. Further, using USO observations, we have identified the sites of new flux emergences, large proper motions and line-of-sight velocity flows in the active region and their relationship with the flare.

  15. 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. PMID:25951292

  16. 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.

  17. Weak Langmuir optical turbulence in a fiber cavity

    NASA Astrophysics Data System (ADS)

    Xu, G.; Garnier, J.; Mussot, A.; Trillo, S.; Churkin, D.; Tarasov, N.; Turitsyn, S.; Picozzi, A.

    2016-07-01

    We study theoretically and numerically the dynamics of a passive optical fiber ring cavity pumped by a highly incoherent wave: an incoherently injected fiber laser. The theoretical analysis reveals that the turbulent dynamics of the cavity is dominated by the Raman effect. The forced-dissipative nature of the fiber cavity is responsible for a large diversity of turbulent behaviors: Aside from nonequilibrium statistical stationary states, we report the formation of a periodic pattern of spectral incoherent solitons, or the formation of different types of spectral singularities, e.g., dispersive shock waves and incoherent spectral collapse behaviors. We derive a mean-field kinetic equation that describes in detail the different turbulent regimes of the cavity and whose structure is formally analogous to the weak Langmuir turbulence kinetic equation in the presence of forcing and damping. A quantitative agreement is obtained between the simulations of the nonlinear Schrödinger equation with cavity boundary conditions and those of the mean-field kinetic equation and the corresponding singular integrodifferential reduction, without using adjustable parameters. We discuss the possible realization of a fiber cavity experimental setup in which the theoretical predictions can be observed and studied.

  18. 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.

  19. Using a Fiber Loop and Fiber Bragg Grating as a Fiber Optic Sensor to Simultaneously Measure Temperature and Displacement

    PubMed Central

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

    2013-01-01

    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. PMID:23681094

  20. 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

  1. 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.

  2. Large Solar Energetic Particle Events Associated with Filament Eruptions Outside of Active Regions

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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 ˜ 1000 km s-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.

  3. 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.

  4. Coronal holes, large-scale magnetic field, and activity complexes in solar cycle 23

    NASA Astrophysics Data System (ADS)

    Tavastsherna, K. S.; Polyakow, E. V.

    2014-12-01

    A correlation among coronal holes (CH), a large-scale magnetic field (LMF), and activity complexes (AC) is studied in this work for 1997-2007 with the use of a coronal hole series obtained from observations at the Kitt Peak Observatory in the HeI 10830 Å line in 1975-2003 and SOHO/EIT-195 Å in 1996-2012 (Tlatov et al., 2014), synoptic Hα charts from Kislovodsk Mountain Astonomical Station, and the catalog of AC cores (Yazev, 2012). From the imposition of CH boundaries on Hα charts, which characterize the positions of neutral lines of the radial components of a large-scale solar magnetic field, it turns out that 70% of CH are located in unipolar regions of their sign during the above period, 10% are in the region of an opposite sign, and 20% are mainly very large CH, which are often crossed by the neutral lines of several unipolar regions. Data on mutual arrangement of CH and AC cores were obtained. It was shown that only some activity comples cores have genetic relationships with CH.

  5. 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.

  6. 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

    2016-01-01

    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. PMID:26848693

  7. 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.

  8. Constitutive STAT6 activation in primary mediastinal large B-cell lymphoma.

    PubMed

    Guiter, Chrystelle; Dusanter-Fourt, Isabelle; Copie-Bergman, Christiane; Boulland, Marie-Laure; Le Gouvello, Sabine; Gaulard, Philippe; Leroy, Karen; Castellano, Flavia

    2004-07-15

    Primary mediastinal large B-cell lymphoma (PMBL), currently recognized as a diffuse large B-cell lymphoma (DLBCL) subtype, shows increased expression of interleukin 4 (IL-4)/IL-13 signaling effectors and targets, suggesting constitutive activation of these pathways. We therefore investigated the functional state of the signal transducer and activator of transcription 6 (STAT6), mediating IL-4/IL-13 transcriptional effects. Constitutive STAT6 phosphorylation and DNA-binding activity were detected in PMBL cell lines but not DLBCL cell lines. Moreover, immunohistochemical analysis revealed nuclear phosphorylated STAT6 (P-STAT6) in 8 of 11 PMBL, compared with 1 of 10 DLBCL primary tumors (P =.01). IL-4 and IL-13 transcripts were absent in PMBL cell lines and expressed at low levels in tumors, indicating that, contrary to classical Hodgkin lymphoma (cHL), STAT6 activation is not due to an autocrine IL-4/IL-13 secretion. We demonstrated an amplification of the JAK2 gene in 2 of 6 PMBL cases, and showed higher JAK2 mRNA levels in PMBL compared with DLBCL (P =.005). The Janus kinase 2 (JAK2) was constitutively phosphorylated in the PMBL MedB1 cell line. MedB1 treatment with JAK2 inhibitor AG490 partially decreased STAT6 phosphorylation, suggesting that JAK2 is partially involved in STAT6 activation in these cells. Our findings highlight phosphorylated STAT6 as a characteristic distinguishing PMBL from DLBCL, but a common feature to PMBL and cHL, supporting the hypothesis of common pathogenic events in these 2 lymphomas. PMID:15044251

  9. 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.

  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. 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.

  12. Active and passive acoustic imaging inside a large-scale polyaxial hydraulic fracture test

    SciTech Connect

    Glaser, S.D.; Dudley, J.W. II; Shlyapobersky, J.

    1999-07-01

    An automated laboratory hydraulic fracture experiment has been assembled to determine what rock and treatment parameters are crucial to improving the efficiency and effectiveness of field hydraulic fractures. To this end a large (460 mm cubic sample) polyaxial cell, with servo-controlled X,Y,Z, pore pressure, crack-mouth-opening-displacement, and bottom hole pressure, was built. Active imaging with embedded seismic diffraction arrays images the geometry of the fracture. Preliminary tests indicate fracture extent can be imaged to within 5%. Unique embeddible high-fidelity particle velocity AE sensors were designed and calibrated to allow determination of fracture source kinematics.

  13. Large scale photospheric magnetic field: The diffusion of active region fields

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Leighton, R. B.; Howard, R.; Wilcox, J. M.

    1972-01-01

    The large-scale phototospheric magnetic field was computed by allowing observed active region fields to diffuse and to be sheared by differential rotation in accordance with the Leighton (1969) magneto-kinematic model of the solar cycle. The differential rotation of the computed field patterns as determined by autocorrelation curves is similar to that of the observed photospheric field, and poleward of 20 deg. latitude both are significantly different from the differential rotation of the long-lived sunspots (Newton and Nunn, 1951) used as an input into the computations.

  14. 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.

  15. 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

  16. Active wavefront control challenges of the NASA Large Deployable Reflector (LDR)

    NASA Technical Reports Server (NTRS)

    Meinel, Aden B.; Meinel, Marjorie P.; Manhart, Paul K.; Hochberg, Eric B.

    1989-01-01

    The 20-m Large Deployable Reflector will have a segmented primary mirror. Achieving diffraction-limited performance at 50 microns requires correction for the errors of tilt and piston of the primary mirror. This correction can be obtained in two ways, the use of an active primary or a correction at a demagnified pupil of the primary. A critical requirement is the means for measurement of the wavefront error and maintaining phasing during the observation of objects that may be too faint for determining the error. Absolute phasing can only be determined using a cooperative source. Maintenance of phasing can be done with an on-board source. A number of options are being explored as discussed below. The many issues concerning the assessment and control of an active segmented mirror will be addressed with an early construction of the Precision Segmented Reflector testbed.

  17. 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

  18. Activation process in excitable systems with multiple noise sources: Large number of units.

    PubMed

    Franović, Igor; Perc, Matjaž; Todorović, Kristina; Kostić, Srdjan; Burić, Nikola

    2015-12-01

    We study the activation process in large assemblies of type II excitable units whose dynamics is influenced by two independent noise terms. The mean-field approach is applied to explicitly demonstrate that the assembly of excitable units can itself exhibit macroscopic excitable behavior. In order to facilitate the comparison between the excitable dynamics of a single unit and an assembly, we introduce three distinct formulations of the assembly activation event. Each formulation treats different aspects of the relevant phenomena, including the thresholdlike behavior and the role of coherence of individual spikes. Statistical properties of the assembly activation process, such as the mean time-to-first pulse and the associated coefficient of variation, are found to be qualitatively analogous for all three formulations, as well as to resemble the results for a single unit. These analogies are shown to derive from the fact that global variables undergo a stochastic bifurcation from the stochastically stable fixed point to continuous oscillations. Local activation processes are analyzed in the light of the competition between the noise-led and the relaxation-driven dynamics. We also briefly report on a system-size antiresonant effect displayed by the mean time-to-first pulse. PMID:26764779

  19. 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.

  20. 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.

  1. 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.

  2. Behavioral stochastic resonance associated with large-scale synchronization of human brain activity

    NASA Astrophysics Data System (ADS)

    Kitajo, Keiichi; Yamanaka, Kentaro; Nozaki, Daichi; Ward, Lawrence M.; Yamamoto, Yoshiharu

    2004-05-01

    We demonstrate experimentally that enhanced detection of weak visual signals by addition of visual noise is accompanied by an increase in phase synchronization of EEG signals across widely-separated areas of the human brain. In our sensorimotor integration task, observers responded to a weak rectangular gray-level signal presented to their right eyes by pressing and releasing a button whenever they detected an increment followed by a decrement in brightness. Signal detection performance was optimized by presenting randomly-changing-gray-level noise separately to observers' left eyes using a mirror stereoscope. We measured brain electrical activity at the scalp by electroencephalograph (EEG), calculated the instantaneous phase for each EEG signal, and evaluated the degree of large-scale phase synchronization between pairs of EEG signals. Dynamic synchronization-desynchronization patterns were observed and we found evidence of noise-enhanced large-scale synchronization associated with detection of the brightness changes under conditions of noise-enhanced performance. Our results suggest that behavioral stochastic resonance might arise from noise-enhanced synchronization of neural activities across widespread brain regions.

  3. Three-element trap filter radiometer based on large active area silicon photodiodes.

    PubMed

    Salim, S G R; Anhalt, K; Taubert, D R; Hollandt, J

    2016-05-20

    This paper shows the opto-mechanical design of a new filter radiometer built at the Physikalisch-Technische Bundesanstalt, Germany, for the accurate determination of the thermodynamic temperature of high-temperature blackbodies. The filter radiometer is based on a three-element reflection-type trap detector that uses three large active area silicon photodiodes. Its spectral coverage and field of view are defined by a detachable narrow-band filter and a diamond-turned precision aperture, respectively. The temperature of the filter radiometer is stabilized using a water-streamed housing and is measured using a thin-film platinum thermometer placed onto the first photodiode element. The trap "mount" has been made as compact as possible, which, together with the large active area of the chosen photodiodes, allows a wide field of view. This work presents the design of the filter radiometer and discusses the criteria that have been considered in order for the filter radiometer to suit the application.

  4. 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. PMID:25822633

  5. Three-element trap filter radiometer based on large active area silicon photodiodes.

    PubMed

    Salim, S G R; Anhalt, K; Taubert, D R; Hollandt, J

    2016-05-20

    This paper shows the opto-mechanical design of a new filter radiometer built at the Physikalisch-Technische Bundesanstalt, Germany, for the accurate determination of the thermodynamic temperature of high-temperature blackbodies. The filter radiometer is based on a three-element reflection-type trap detector that uses three large active area silicon photodiodes. Its spectral coverage and field of view are defined by a detachable narrow-band filter and a diamond-turned precision aperture, respectively. The temperature of the filter radiometer is stabilized using a water-streamed housing and is measured using a thin-film platinum thermometer placed onto the first photodiode element. The trap "mount" has been made as compact as possible, which, together with the large active area of the chosen photodiodes, allows a wide field of view. This work presents the design of the filter radiometer and discusses the criteria that have been considered in order for the filter radiometer to suit the application. PMID:27411121

  6. 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.

  7. 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

  8. 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

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

    PubMed

    Pérez, Guillermo J; Desai, Mayurika; Anderson, Seth; Scornik, Fabiana S

    2013-02-01

    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.

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

    PubMed

    Chen, Qijing; Tao, Jie; 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

  11. Experimental demonstration of nonlinear pulse propagation in a fiber Bragg grating written in a fiber amplifier.

    PubMed

    Shapira, Y P; Smulakovsky, V; Horowitz, M

    2016-01-01

    We study experimentally nonlinear propagation of sub-nanosecond optical pulses in a fiber Bragg grating written in a Ytterbium-doped fiber amplifier (YD-FBG). The magnitude and the sign of group velocity dispersion (GVD) in YD-FBG can be controlled by adjusting the fiber tension. In the case of anomalous GVD, pulse breakup was observed due to modulation instability. However, for the same input pulse power in the normal GVD regime, the output pulse duration was increased, and pulse breakup was not observed. The deterioration of pulse spectrum due to Raman and four-wave mixing effect was also reduced in the normal GVD regime. Since GVD in YD-FBG is six orders of magnitude higher than in standard fibers, the advantages of normal GVD in fiber amplifiers that were demonstrated in previous works for femtosecond and picosecond pulses can be exploited for amplifying sub-nanosecond pulses. The experimental results are in good agreement with numerical simulations. We have also demonstrated a gain coefficient enhancement by a factor of 1.7 due to slow-light propagation in the YD-FBG. PMID:26696144

  12. 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

    2015-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    2015-07-01

    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. 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

    2015-07-01

    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. PMID:26135448

  15. 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.

  16. 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.

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

    PubMed

    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. PMID:18643304

  18. Physical changes within a large tropical hydroelectric reservoir induced by wintertime cold front activity

    NASA Astrophysics Data System (ADS)

    Curtarelli, M. P.; Alcântara, E. H.; Rennó, C. D.; Stech, J. L.

    2014-08-01

    We investigated the influence of wintertime cold front activity on the physical processes within a large tropical reservoir located in Brazil. The period chosen for this study consisted of 49 days between 28 April 2010 and 15 July 2010. This period was defined based on information from the Brazilian Center for Weather Forecasting and Climate Studies (CPTEC), data collected in situ and the interpretation of remotely sensed images. To better understand the governing processes that drive changes in the heat balance, differential cooling and mixing dynamics, a simulation was performed that utilized a three-dimensional hydrodynamic model enforced with in situ and remote sensing data. The results showed that during a cold front passage over the reservoir, the sensible and latent heat fluxes were enhanced by approximately 77 and 16%, respectively. The reservoir's daily averaged heat loss was up to 167% higher on the days with cold front activity than on the days without activity. The cold front passage also intensified the differential cooling process; in some cases the difference between the water temperature of the littoral and pelagic zones reached up to 8 °C. The occurrence of cold front passages impacted the diurnal mixed layer (DML), by increasing the turbulent energy input (∼54%) and the DML depth (∼41%). Our results indicate that the cold front events are one of the main meteorological disturbances driving the physical processes within hydroelectric reservoirs located in tropical South America during the wintertime. Hence, cold front activity over these aquatic systems has several implications for water quality and reservoir management in Brazil.

  19. 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.

  20. Large-Area, Highly Ordered Array of Graphitic Carbon Materials Using Surface Active Chitosan Prepatterns.

    PubMed

    Baek, Youn-Kyoung; Kim, Dae Woo; Yang, Seung Bo; Lee, Jung-Goo; Kim, Young Kuk; Jung, Hee-Tae

    2015-02-01

    We demonstrate that chitosan prepatterns can generate not only highly periodic DNA pattern but also various types of graphitic carbon materials such as single-walled carbon nanotubes (SWNTs), graphene oxide (GO) and reduced graphene oxide (RGO). Scanning electron microscopy (SEM), fluorescence imaging and Raman spectroscopic results revealed that the graphitic carbon materials were selectively deposited on the surface of the periodic chitosan patterns by the electrostatic interaction between protonated amine groups of chitosan and the negative charged carbon materials. One proof-of-concept application of the system to the fabrication of electrical devices based on the micropatterns of SWNTs and RGO was also demonstrated. The strategy to use highly surface active chitosan pattern that can easily fabricate highly periodic pattern via a variety of lithographic tools may pave the way for the production of periodic arrays of graphitic carbon materials for large area device integration. PMID:26353637

  1. 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.

  2. 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. PMID:27515518

  3. 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.

  4. 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.

  5. 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.

  6. Neutral buoyancy evaluation of extravehicular activity assembly of a large precision reflector

    NASA Technical Reports Server (NTRS)

    Heard, Walter L., Jr.; Lake, Mark S.

    1993-01-01

    A procedure that enables astronauts in extravehicular activity (EVA) to perform efficient on-orbit assembly of large paraboloidal precision reflectors is presented. The procedure and associated hardware are verified in simulated Og (neutral buoyancy) assembly tests of a 14m-diameter precision reflector mockup. The test article represents a precision reflector having a reflective surface which is segmented into 37 individual panels. The panels are supported on a doubly curved tetrahedral truss consisting of 315 struts. The entire truss and seven reflector panels were assembled in three hours and seven minutes by two pressure-suited test subjects. The average time to attach a panel was two minutes and three seconds. These efficient assembly times were achieved because all hardware and assembly procedures were designed to be compatible with EVA assembly capabilities.

  7. 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.

  8. 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.

  9. 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.

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

    PubMed

    Jovan Jose, K V; Raghavachari, Krishnan

    2016-02-01

    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.

  11. A conserved hydrophobic surface of the LARG pleckstrin homology domain is critical for RhoA activation in cells

    PubMed Central

    Aittaleb, Mohamed; Gao, Guang; Evelyn, Chris R.; Neubig, Richard R.; Tesmer, John J. G.

    2009-01-01

    Leukemia associated Rho guanine nucleotide exchange factor (LARG) activates RhoA in response to signals received by specific classes of cell surface receptors. The catalytic core of LARG is a Dbl homology (DH) domain whose activity is modulated by an adjacent pleckstrin homology (PH) domain. In this study, we used a transcriptional assay and confocal microscopy to examine the roles of several novel structural features of the LARG DH/PH domains, including a conserved and exposed hydrophobic patch on the PH domain that mediates protein-protein interactions in crystal structures of LARG and its close homolog PDZ-RhoGEF. Mutation of the hydrophobic patch has no effect on nucleotide exchange activity in vitro, but abolished the ability of LARG to activate RhoA and to induce stress fiber formation in cultured cells. The activity of these mutants could be rescued by fusion with exogenous membrane targeting domains. However, because membrane recruitment by activated Gα13 subunits was not sufficient to rescue activity of a hydrophobic patch mutant, the LARG PH domain cannot solely contribute to membrane targeting. Instead, it seems likely the domain is involved in regulatory interactions with other proteins near the membrane surface. We also show that the hydrophobic patch of the PH domain is likely important for the activity of all Lbc family RhoGEFs. PMID:19560536

  12. 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

  13. 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.

  14. Vertebrate Protein CTCF and its Multiple Roles in a Large-Scale Regulation of Genome Activity

    PubMed Central

    Nikolaev, L.G; Akopov, S.B; Didych, D.A; Sverdlov, E.D

    2009-01-01

    The CTCF transcription factor is an 11 zinc fingers multifunctional protein that uses different zinc finger combinations to recognize and bind different sites within DNA. CTCF is thought to participate in various gene regulatory networks including transcription activation and repression, formation of independently functioning chromatin domains and regulation of imprinting. Sequencing of human and other genomes opened up a possibility to ascertain the genomic distribution of CTCF binding sites and to identify CTCF-dependent cis-regulatory elements, including insulators. In the review, we summarized recent data on genomic distribution of CTCF binding sites in the human and other genomes within a framework of the loop domain hypothesis of large-scale regulation of the genome activity. We also tried to formulate possible lines of studies on a variety of CTCF functions which probably depend on its ability to specifically bind DNA, interact with other proteins and form di- and multimers. These three fundamental properties allow CTCF to serve as a transcription factor, an insulator and a constitutive dispersed genome-wide demarcation tool able to recruit various factors that emerge in response to diverse external and internal signals, and thus to exert its signal-specific function(s). PMID:20119526

  15. Vertebrate Protein CTCF and its Multiple Roles in a Large-Scale Regulation of Genome Activity.

    PubMed

    Nikolaev, L G; Akopov, S B; Didych, D A; Sverdlov, E D

    2009-08-01

    The CTCF transcription factor is an 11 zinc fingers multifunctional protein that uses different zinc finger combinations to recognize and bind different sites within DNA. CTCF is thought to participate in various gene regulatory networks including transcription activation and repression, formation of independently functioning chromatin domains and regulation of imprinting. Sequencing of human and other genomes opened up a possibility to ascertain the genomic distribution of CTCF binding sites and to identify CTCF-dependent cis-regulatory elements, including insulators. In the review, we summarized recent data on genomic distribution of CTCF binding sites in the human and other genomes within a framework of the loop domain hypothesis of large-scale regulation of the genome activity. We also tried to formulate possible lines of studies on a variety of CTCF functions which probably depend on its ability to specifically bind DNA, interact with other proteins and form di- and multimers. These three fundamental properties allow CTCF to serve as a transcription factor, an insulator and a constitutive dispersed genome-wide demarcation tool able to recruit various factors that emerge in response to diverse external and internal signals, and thus to exert its signal-specific function(s). PMID:20119526

  16. 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

  17. 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

  18. 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

  19. 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

  20. Isolation of a Hemagglutinin with Potent Antiproliferative Activity and a Large Antifungal Defensin from Phaseolus vulgaris cv. Hokkaido Large Pinto Beans.

    PubMed

    Yin, Cuiming; Wong, Jack Ho; Ng, Tzi Bun

    2015-06-10

    Lectins (hemagglutinins) are defined as sugar-binding proteins or glycoproteins with various biological activities. A 60 kDa dimeric hemagglutinin with a blocked N-terminus was isolated in large yield (190 mg/60 g) from the common edible bean Phaseolus vulgaris cv. Hokkaido large pinto bean. Its hemagglutinating, antifungal, and antitumor activities as well as the effects of carbohydrate and metal ions on its hemagglutinating activity were examined. It inhibited the proliferation of nasopharyngeal carcinoma (CNE2), human breast cancer (MCF7), and hepatoma (HepG2) cells. The IC50 values toward HepG2, MCF7, and CNE2 cells after treatment for 48 h were 8.1, 6.07, and 7.49 μM, respectively, which were relatively low among lectins of different P. vulgaris cultivars. From the pinto beans, a 10888 Da antifungal peptide with similarity to plant defensins as revealed by mass spectroscopic analysis was also isolated with a yield of 3.2 mg of proteins from 60 g of beans. The large defensin was capable of inhibiting mycelial growth in Mycosphaerella arachidicola, Setosphaeria turcica, Bipolaris maydis, and Fusarium oxysporum but not in Valsa mali. PMID:25965006

  1. 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).

  2. Experimental demonstration of a fiber Bragg grating accelerometer

    SciTech Connect

    Berkoff, T.A.; Kersey, A.D.

    1996-12-01

    The authors report a fiber Bragg grating transducer for the measurement of acceleration. Results obtained using interferometric wavelength-shift detection demonstrate a demodulated signal output range of 50-g rms with a minimum detectable signal of {approximately}1 mg/{radical}Hz.

  3. 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.

  4. Using a laser tracker for active alignment on the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Rakich, A.

    2012-09-01

    The Large Binocular Telescope (LBT) currently achieves collimation using a combination of collimation models and closed-loop active correction schemes. Shack Hartmann wavefront sensors with off-axis guide stars are used for Gregorian modes, and a closed-loop correction scheme is used for the prime-focus cameras. While in general this combination serves to produce alignment residuals well below a good seeing limit within a few minutes of obtaining a given target field, the uniquely asymmetrical structure of the LBT is prone to producing large deflections of the telescope optics when the ambient temperature is changing unusually rapidly. These deflections are difficult to model satisfactorily, and are an ongoing source of inefficiency in telescope operations. Furthermore, none of the current approaches to telescope collimation are particularly "piston aware"; a situation that needs to be improved on now that the LBT is commencing operations with the first of its beam combining instruments, LBTI. The laser tracker is a metrology instrument capable of automatically measuring optical element positions with better than 100 micron precision within a spherical volume of 30 m radius centered on the tracker head. With the ability to directly measure optics into position to this accuracy built into the Telescope Control System (TCS), the LBT would always be starting observations from a point of near-collimation, the component telescopes would be co-pointed, and the OPD would be well within the capture range of the beam combining instrument's internal phasing systems. This paper describes first results from engineering investigations into using the laser tracker to automatically align the optics on the LBT.

  5. 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

  6. 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

  7. 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

  8. 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

  9. Plasmon-mediated large enhancement of magneto-optical activity in colloidal magnetic metals

    NASA Astrophysics Data System (ADS)

    Herranz, Gervasi; Vlasin, Ondrej; Pascu, Oana; Roig, Anna

    2014-03-01

    Magnetic properties may undergo dramatic changes at the nanoscale that, eventually, can be exploited as a basis for enhanced functionality. This is the case that we present here, in which we analyzed the rotation and ellipticity that magnetic nanoparticles exerted on the polarization of light. More specifically, we observed an outstanding increase of the magneto-optical activity at the frequencies of the plasmon resonances of the metallic magnetic nanoparticles, yielding a dramatic increase of the Verdet constant. Furthermore, we have established an innovative theoretical framework in excellent quantitative agreement with the experimental data, endowing our model with a powerful predictive character for the interaction of polarized light with magnetic nanoclusters embedded in dielectric hosts. The relevance of our results goes well beyond the particular case of colloidal metals, as other systems such as metal inclusions in polymers or glasses containing small magnetic clusters can be as well considered. In addition, the observed large Verdet constants allow envisioning the exploitation of light polarization, instead as the commonly used reflectance, as a probe for plasmon-sensing devices. Our results provide new routes for plasmon-based biological and chemical detection.

  10. Four-point probe electrical resistivity scanning system for large area conductivity and activation energy mapping.

    PubMed

    Shimanovich, Klimentiy; Bouhadana, Yaniv; Keller, David A; Rühle, Sven; Anderson, Assaf Y; Zaban, Arie

    2014-05-01

    The electrical properties of metal oxides play a crucial role in the development of new photovoltaic (PV) systems. Here we demonstrate a general approach for the determination and analysis of these properties in thin films of new metal oxide based PV materials. A high throughput electrical scanning system, which facilitates temperature dependent measurements at different atmospheres for highly resistive samples, was designed and constructed. The instrument is capable of determining conductivity and activation energy values for relatively large sample areas, of about 72 × 72 mm(2), with the implementation of geometrical correction factors. The efficiency of our scanning system was tested using two different samples of CuO and commercially available Fluorine doped tin oxide coated glass substrates. Our high throughput tool was able to identify the electrical properties of both resistive metal oxide thin film samples with high precision and accuracy. The scanning system enabled us to gain insight into transport mechanisms with novel compositions and to use those insights to make smart choices when choosing materials for our multilayer thin film all oxide photovoltaic cells. PMID:24880411

  11. 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.

  12. 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). PMID:26828845

  13. ACTIVE LONGITUDES REVEALED BY LARGE-SCALE AND LONG-LIVED CORONAL STREAMERS

    SciTech Connect

    Li Jing

    2011-07-10

    We use time-series ultraviolet full sun images to construct limb-synoptic maps of the Sun. On these maps, large-scale, long-lived coronal streamers appear as repetitive sinusoid-like arcs projected over the polar regions. They are caused by high altitude plasma produced from sunspot-rich regions at latitudes generally far from the poles. The non-uniform longitudinal distribution of these streamers reveals four longitudinal zones at the surface of the Sun from which sunspots erupt preferentially over the 5 year observing interval (2006 January to 2011 April). Spots in these zones (or clusters) have individual lifetimes short compared to the lifetimes of the coronal features which they sustain, and they erupt at different times. The four sunspot clusters contain >75% of all numbered sunspots in this period. They occupy two distinct longitudinal zones separated by {approx}180{sup 0} and each spanning {approx}100{sup 0} in longitude. The rotation rates of the spot clusters are {approx}5% faster than the rates at both the surface and the bottom of the convection zone. While no convincing theoretical framework exists to interpret the sunspot clusters in the longitude-time space, their persistent and nonuniform distribution indicates long-lived, azimuthal structures beneath the surface, and are compatible with the existence of previously reported active longitudes on the Sun.

  14. 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.

  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 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.

  17. 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.

  18. Porous capsules with a large number of active sites: nucleation/growth under confined conditions.

    PubMed

    Garai, Somenath; Rubčić, Mirta; Bögge, Hartmut; Gouzerh, Pierre; Müller, Achim

    2015-03-01

    This work deals with the generation of large numbers of active sites and with ensuing nucleation/ growth processes on the inside wall of the cavity of porous nanocapsules of the type (pentagon)12(linker)30≡{(Mo(VI))Mo(VI)5}12{Mo(V)2(ligand)}30. A first example refers to sulfur dioxide capture through displacement of acetate ligands, while the grafted sulfite ligands are able to trap {MoO3H}(+) units thereby forming unusual {(O2SO)3MoO3H}(5-) assemblies. A second example relates to the generation of open coordination sites through release of carbon dioxide upon mild acidification of a carbonate-type capsule. When the reaction is performed in the presence of heptamolybdate ions, MoO4(2-) ions enter the cavity where they bind to the inside wall while forming new types of polyoxomolybdate architectures, thereby extending the molybdenum oxide skeleton of the capsule. Parallels can be drawn with Mo-storage proteins and supported MoO3 catalysts, making the results relevant to molybdenum biochemistry and to catalysis. PMID:25653204

  19. 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).

  20. 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.

  1. 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.

  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. Unraveling Kinase Activation Dynamics Using Kinase-Substrate Relationships from Temporal Large-Scale Phosphoproteomics Studies.

    PubMed

    Domanova, Westa; Krycer, James; Chaudhuri, Rima; Yang, Pengyi; Vafaee, Fatemeh; Fazakerley, Daniel; Humphrey, Sean; James, David; Kuncic, Zdenka

    2016-01-01

    In response to stimuli, biological processes are tightly controlled by dynamic cellular signaling mechanisms. Reversible protein phosphorylation occurs on rapid time-scales (milliseconds to seconds), making it an ideal carrier of these signals. Advances in mass spectrometry-based proteomics have led to the identification of many tens of thousands of phosphorylation sites, yet for the majority of these the kinase is unknown and the underlying network topology of signaling networks therefore remains obscured. Identifying kinase substrate relationships (KSRs) is therefore an important goal in cell signaling research. Existing consensus sequence motif based prediction algorithms do not consider the biological context of KSRs, and are therefore insensitive to many other mechanisms guiding kinase-substrate recognition in cellular contexts. Here, we use temporal information to identify biologically relevant KSRs from Large-scale In Vivo Experiments (KSR-LIVE) in a data-dependent and automated fashion. First, we used available phosphorylation databases to construct a repository of existing experimentally-predicted KSRs. For each kinase in this database, we used time-resolved phosphoproteomics data to examine how its substrates changed in phosphorylation over time. Although substrates for a particular kinase clustered together, they often exhibited a different temporal pattern to the phosphorylation of the kinase. Therefore, although phosphorylation regulates kinase activity, our findings imply that substrate phosphorylation likely serve as a better proxy for kinase activity than kinase phosphorylation. KSR-LIVE can thereby infer which kinases are regulated within a biological context. Moreover, KSR-LIVE can also be used to automatically generate positive training sets for the subsequent prediction of novel KSRs using machine learning approaches. We demonstrate that this approach can distinguish between Akt and Rps6kb1, two kinases that share the same linear consensus motif

  4. Unraveling Kinase Activation Dynamics Using Kinase-Substrate Relationships from Temporal Large-Scale Phosphoproteomics Studies

    PubMed Central

    Chaudhuri, Rima; Yang, Pengyi; Vafaee, Fatemeh; Fazakerley, Daniel; Humphrey, Sean; James, David; Kuncic, Zdenka

    2016-01-01

    In response to stimuli, biological processes are tightly controlled by dynamic cellular signaling mechanisms. Reversible protein phosphorylation occurs on rapid time-scales (milliseconds to seconds), making it an ideal carrier of these signals. Advances in mass spectrometry-based proteomics have led to the identification of many tens of thousands of phosphorylation sites, yet for the majority of these the kinase is unknown and the underlying network topology of signaling networks therefore remains obscured. Identifying kinase substrate relationships (KSRs) is therefore an important goal in cell signaling research. Existing consensus sequence motif based prediction algorithms do not consider the biological context of KSRs, and are therefore insensitive to many other mechanisms guiding kinase-substrate recognition in cellular contexts. Here, we use temporal information to identify biologically relevant KSRs from Large-scale In Vivo Experiments (KSR-LIVE) in a data-dependent and automated fashion. First, we used available phosphorylation databases to construct a repository of existing experimentally-predicted KSRs. For each kinase in this database, we used time-resolved phosphoproteomics data to examine how its substrates changed in phosphorylation over time. Although substrates for a particular kinase clustered together, they often exhibited a different temporal pattern to the phosphorylation of the kinase. Therefore, although phosphorylation regulates kinase activity, our findings imply that substrate phosphorylation likely serve as a better proxy for kinase activity than kinase phosphorylation. KSR-LIVE can thereby infer which kinases are regulated within a biological context. Moreover, KSR-LIVE can also be used to automatically generate positive training sets for the subsequent prediction of novel KSRs using machine learning approaches. We demonstrate that this approach can distinguish between Akt and Rps6kb1, two kinases that share the same linear consensus motif

  5. 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

  6. Aircraft emissions and local air quality impacts from takeoff activities at a large International Airport

    NASA Astrophysics Data System (ADS)

    Zhu, Yifang; Fanning, Elinor; Yu, Rong Chun; Zhang, Qunfang; Froines, John R.

    2011-11-01

    Real time number concentrations and size distributions of ultrafine particles (UFPs, diameter <100 nm) and time integrated black carbon, PM 2.5 mass, and chemical species were studied at the Los Angeles International Airport (LAX) and a background reference site. At LAX, data were collected at the blast fence (˜140 m from the takeoff position) and five downwind sites up to 600 m from the takeoff runway and upwind of the 405 freeway. Size distributions of UFPs collected at the blast fence site showed very high number concentrations, with the highest numbers found at a particle size of approximately 14 nm. The highest spikes in the time series profile of UFP number concentrations were correlated with individual aircraft takeoff. Measurements indicate a more than 100-fold difference in particle number concentrations between the highest spikes during takeoffs and the lowest concentrations when no takeoff is occurring. Total UFP counts exceeded 10 7 particles cm -3 during some monitored takeoffs. Time averaged concentrations of PM 2.5 mass and two carbonyl compounds, formaldehyde and acrolein, were statistically elevated at the airport site relative to a background reference site. Peaks of 15 nm particles, associated with aircraft takeoffs, that occurred at the blast fence were matched with peaks observed 600 m downwind, with time lags of less than 1 min. The results of this study demonstrate that commercial aircraft at LAX emit large quantities of UFP at the lower end of currently measurable particle size ranges. The observed highly elevated UFP concentrations downwind of LAX associated with aircraft takeoff activities have significant exposure and possible health implications.

  7. 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

  8. 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 Detectives"; (2)…

  9. Large Enhancement in Electrorheological Activity of Mesoporous Cerium-Doped TIO2 from High Surface Area and Robust Pore Walls

    NASA Astrophysics Data System (ADS)

    Yin, Jianbo; Zhao, Xiaopeng

    Considering the importance of large interfacial or surface polarization to strong electrorheological (ER) effect, we developed a high surface area mesoporous doped TiO2 ER material by using block-copolymer. By comparing the ER experiments between samples with mesopore and without mesopore, we demonstrate a very large enhancement in ER activity of mesoporous ER material and its yield stress is 100 times that of the pure TiO2 ER material and 5-8 times that of single doped TiO2 without mesoporous structure. We give a preliminary discussion about the improvement in ER activity based on previous dielectric analysis.

  10. Can the activities of the large scale cortical network be expressed by neural energy? A brief review.

    PubMed

    Wang, Rubin; Zhu, Yating

    2016-02-01

    This paper mainly discusses and summarize that the changes of biological energy in the brain can be expressed by the biophysical energy we constructed. Different from the electrochemical energy, the biophysical energy proposed in the paper not only can be used to simulate the activity of neurons but also be used to simulate the neural activity of large scale cortical networks, so that the scientific nature of the neural energy coding was discussed.

  11. 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.

  12. 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

  13. 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…

  14. 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…

  15. 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…

  16. 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.

  17. 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…

  18. 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.

  19. 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

  20. 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.

  1. Nonlinear tunneling in a fiber guide array resonator.

    PubMed

    Leon, Jérôme

    2004-11-01

    A fiber guide array resonator is proposed and shown to obey a nonlinear Schrödinger model in a square well potential with nonlinearity defocusing inside the well and focusing outside. This model is proved to possess nonlinear states which are i) continuous extensions of the linear eigenstates, ii) remarkably stable up to a threshold amplitude, iii) unstable at the threshold where nonlinear tunneling occurs by gap soliton emission outside the well. This allows in particular to obtain soliton formation by constant wave irradiation of the fiber guide array resonator. An explicit analytic expression of the threshold is given in terms of the well size for each level. PMID:15600776

  2. 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.

  3. Imaging large-scale neural activity with cellular resolution in awake, mobile mice.

    PubMed

    Dombeck, Daniel A; Khabbaz, Anton N; Collman, Forrest; Adelman, Thomas L; Tank, David W

    2007-10-01

    We report a technique for two-photon fluorescence imaging with cellular resolution in awake, behaving mice with minimal motion artifact. The apparatus combines an upright, table-mounted two-photon microscope with a spherical treadmill consisting of a large, air-supported Styrofoam ball. Mice, with implanted cranial windows, are head restrained under the objective while their limbs rest on the ball's upper surface. Following adaptation to head restraint, mice maneuver on the spherical treadmill as their heads remain motionless. Image sequences demonstrate that running-associated brain motion is limited to approximately 2-5 microm. In addition, motion is predominantly in the focal plane, with little out-of-plane motion, making the application of a custom-designed Hidden-Markov-Model-based motion correction algorithm useful for postprocessing. Behaviorally correlated calcium transients from large neuronal and astrocytic populations were routinely measured, with an estimated motion-induced false positive error rate of <5%.

  4. Quisqualate-activated single channel currents in neuromuscular preparations of small and large crayfish.

    PubMed

    Finger, W; Martin, C; Pareto, A

    1988-06-01

    Single channel currents elicited by 1-5 mumol/l quisqualate in neuromuscular preparations in large (greater than 16 month old) and small (1-3 month old) crayfish were recorded by means of the patch-clamp technique. In preparations from large crayfish single channel currents of variable amplitude (-1 to -12 pA) were induced by quisqualate. The mean burst lengths of these currents were tau approximately equal to 1-2 ms. In the opener muscle of the first walking leg and the contractor epimeralis muscle of small crayfish the mean burst lengths of single channel currents evoked by quisqualate were prolonged by a factor of about 4 (tau approximately equal to 5 ms). Moreover, in the opener muscle of the first walking leg of small crayfish single channel currents of small amplitude (-0.5 to -2.5 pA) were preferentially evoked by quisqualate. By contrast, in the contractor epimeralis muscle of small crayfish mainly single channel currents of large amplitude (-10 to -12 pA) were elicited by quisqualate. The results suggest that at the stage of neuromuscular development characterizing the small crayfish, gating properties of excitatory postsynaptic channels are different from those in adult crayfish. Furthermore, the results obtained in the opener muscle of the first walking leg of small crayfish are consistent with those obtained previously by means of the noise analysis technique.

  5. 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.

  6. Holographic fiber bundle system for patterned optogenetic activation of large-scale neuronal networks.

    PubMed

    Farah, Nairouz; Levinsky, Alexandra; Brosh, Inbar; Kahn, Itamar; Shoham, Shy

    2015-10-01

    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

  7. Chronic hypoxia suppresses pregnancy-induced upregulation of large-conductance Ca2+-activated K+ channel activity in uterine arteries.

    PubMed

    Hu, Xiang-Qun; Xiao, Daliao; Zhu, Ronghui; Huang, Xiaohui; Yang, Shumei; Wilson, Sean M; Zhang, Lubo

    2012-07-01

    Our previous study demonstrated that increased Ca(2+)-activated K(+) (BK(Ca)) channel activity played a key role in the normal adaptation of reduced myogenic tone of uterine arteries in pregnancy. The present study tested the hypothesis that chronic hypoxia during gestation inhibits pregnancy-induced upregulation of BK(Ca) channel function in uterine arteries. Resistance-sized uterine arteries were isolated from nonpregnant and near-term pregnant sheep maintained at sea level (≈ 300 m) or exposed to high-altitude (3801 m) hypoxia for 110 days. Hypoxia during gestation significantly inhibited pregnancy-induced upregulation of BK(Ca) channel activity and suppressed BK(Ca) channel current density in pregnant uterine arteries. This was mediated by a selective downregulation of BK(Ca) channel β1 subunit in the uterine arteries. In accordance, hypoxia abrogated the role of the BK(Ca) channel in regulating pressure-induced myogenic tone of uterine arteries that was significantly elevated in pregnant animals acclimatized to chronic hypoxia. In addition, hypoxia abolished the steroid hormone-mediated increase in the β1 subunit and BK(Ca) channel current density observed in nonpregnant uterine arteries. Although the activation of protein kinase C inhibited BK(Ca) channel current density in pregnant uterine arteries of normoxic sheep, this effect was ablated in the hypoxic animals. The results demonstrate that selectively targeting BK(Ca) channel β1 subunit plays a critical role in the maladaption of uteroplacental circulation caused by chronic hypoxia, which contributes to the increased incidence of preeclampsia and fetal intrauterine growth restriction associated with gestational hypoxia. PMID:22665123

  8. Flight testing of a fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Finney, M. J.; Tregay, G. W.; Calabrese, P. R.

    1993-01-01

    A fiber optic temperature sensor (FOTS) system consisting of an optical probe, a flexible fiber optic cable, and an electro-optic signal processor was fabricated to measure the gas temperature in a turbine engine. The optical probe contained an emissive source embedded in a sapphire lightguide coupled to a fiber-optic jumper cable and was retrofitted into an existing thermocouple probe housing. The flexible fiber optic cable was constructed with 200 micron core, polyimide-coated fiber and was ruggedized for an aircraft environment. The electro-optic signal processing unit was used to ratio the intensities of two wavelength intervals and provided an analog output value of the indicated temperature. Subsequently, this optical sensor system was installed on a NASA Dryden F-15 Highly Integrated Digital Electronic Control (HIDEC) Aircraft Engine and several flight tests were conducted. Over the course of flight testing, the FOTS system's response was proportional to the average of the existing thermocouples sensing the changes in turbine engine thermal conditions.

  9. Flight testing of a fiber optic temperature sensor

    NASA Astrophysics Data System (ADS)

    Finney, Mark J.; Tregay, George W.; Calabrese, Paul R.

    1993-02-01

    A fiber optic temperature sensor (FOTS) system consisting of an optical probe, a flexible fiber optic cable, and an electro-optic signal processor was fabricated to measure the gas temperature in a turbine engine. The optical probe contained an emissive source embedded in a sapphire lightguide coupled to a fiber-optic jumper cable and was retrofitted into an existing thermocouple probe housing. The flexible fiber optic cable was constructed with 200 micron core, polyimide-coated fiber and was ruggedized for an aircraft environment. The electro- optic signal processing unit was used to ratio the intensities of two wavelength intervals and provided an analog output value of the indicated temperature. Subsequently, this optical sensors system was installed on a NASA Dryden F-15 Highly Integrated Digital Electronic Control (HIDEC) Aircraft Engine and several flight tests were conducted. Over the course of flight testing, the FOTS system's response was proportional to the average of the existing thermocouples sensing the changes in turbine engine thermal conditions.

  10. Transglutaminase activity is decreased in large arteries from hypertensive rats compared with normotensive controls

    PubMed Central

    Johnson, Kyle B.; Hitomi, Kiyotaka; Tykocki, Nathan R.; Thompson, Janice M.; Watts, Stephanie W.

    2015-01-01

    Transglutaminases (TGs) catalyze the formation of covalent cross-links between glutamine residues and amine groups. This cross-linking activity has been implicated in arterial remodeling. Because hypertension is characterized by arterial remodeling, we hypothesized that TG activity, expression, and functionality would be increased in the aorta, but not in the vena cava (which does not undergo remodeling), from hypertensive rats relative to normotensive rats. Spontaneously hypertensive stroke-prone rats (SHRSP) and DOCA-salt rats as well as their respective normotensive Wistar-Kyoto or Sprague-Dawley counterparts were used. Immunohistochemistry and Western blot analysis measured the presence and expression of TG1 and TG2, in situ activity assays quantified active TGs, and isometric contractility was used to measure TG functionality. Contrary to our hypothesis, the activity (52% DOCA-salt vs. control rats and 56% SHRSP vs. control rats, P < 0.05), expression (TG1: 54% DOCA-salt vs. control rats, P > 0.05, and TG2: 77% DOCA-salt vs. control rats, P < 0.05), and functionality of TG1 and TG2 were decreased in the aorta, but not in the vena cava, from hypertensive rats. Mass spectrometry identified proteins uniquely amidated by TGs in the aorta that play roles in cytoskeletal regulation, redox regulation, and DNA/RNA/protein synthesis and regulation and in the vena cava that play roles in cytoskeletal regulation, coagulation regulation, and cell metabolism. Consistent with the idea that growing cells lose TG2 expression, vascular smooth muscle cells placed in culture lost TG2 expression. We conclude that the expression, activity, and functionality of TG1 and TG2 are decreased in the aorta, but not in the vena cava, from hypertensive rats compared with control rats. PMID:25599570

  11. Enhanced Pixel-Driving Circuits for Active-Matrix Organic-Light-Emitting Diode Displays with Large Sizes

    NASA Astrophysics Data System (ADS)

    Yu, Sang Ho; Choi, Sung Wook; Shin, Hong Jae; Kwack, Kae Dal; Kim, Tae Whan

    2005-03-01

    Enhanced pixel-driving circuits for active-matrix organic-light-emitting diode (AM-OLED) displays with large sizes and highly uniform brightnesses were designed for system on panel. The driving method used the pre-charge functions of the data for a highly uniform brightness during a short time to program the current. The currents of the designed pixel-driving circuits were not significantly affected by variations in the threshold voltages, or by the mobilities of the driving thin-film transistors. These results indicate that the proposed pixel-driving circuits hold promise for potential applications in AM-OLED displays with large sizes and highly uniform brightnesses.

  12. Wireless Laptops as Means for Promoting Active Learning in Large Lecture Halls

    ERIC Educational Resources Information Center

    Barak, Miri; Lipson, Alberta; Lerman, Steven

    2006-01-01

    This paper reports on a study that examined the use of wireless laptops for promoting active learning in lecture halls. The study examined students' behavior in class and their perceptions of the new learning environment throughout three consecutive semesters. An online survey revealed that students have highly positive perceptions about the use…

  13. a New Concept for AN Active Element for the Large Cosmic Ray Calorimeter ANI

    NASA Astrophysics Data System (ADS)

    Steinbuegl, F.; Gebauer, J.; Lorenz, E.; Mirzoyan, R.; Chilingarian, A.; Ferenc, D.; Jokele, B.

    2002-11-01

    For the half completed ANI sampling calorimeter (1600 m2 detection area, 6 concrete absorber layers of 1 m thickness each) at Mount Aragats, Armenia, a cheap and efficient active detector element is needed. A new concept for such a detector element and first results from a reduced size prototype are presented.

  14. 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.

  15. 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

  16. 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.

  17. Present wind activity on Mars - Relation to large latitudinally zoned sediment deposits

    NASA Technical Reports Server (NTRS)

    Thomas, P.

    1982-01-01

    The relation of present Martian winds to large latitudinally zoned sediment deposits has been investigated using global wind streak data and mapping of large sand and dust deposits. Dune sand deposits occur primarily in three latitude belts: north polar (74-85 degrees North), low latitude (5 degrees North-20 degrees South), and south polar (40-80 degrees South). Comparison with wind streak data shows the high-latitude dunes to be in areas of seasonally reversing winds. The present winds can form latitudinal dune belts from a variety of initial dune distributions, including uniform distribution and a polar source. The presence of dune sand within the polar layered deposits, the erosional state of the deposits, and the present surface wind flow away from the poles indicate that both polar dune concentrations have been derived from erosion of the layered deposits. The low-latitude dunes are topographically confined in canyons and craters; they are probably subject to long-term reversal of orientations with climate cycles.

  18. Potentiometric bioimaging with a large-scale integration (LSI)-based electrochemical device for detection of enzyme activity.

    PubMed

    Kanno, Yusuke; Ino, Kosuke; Sakamoto, Chika; Inoue, Kumi Y; Matsudaira, Masahki; Suda, Atsushi; Kunikata, Ryota; Ishikawa, Tomohiro; Abe, Hiroya; Shiku, Hitoshi; Matsue, Tomokazu

    2016-03-15

    This paper describes potentiometric bioimaging for enzyme activity using a large-scale integration (LSI)-based electrochemical device with 400 sensors. Potentiometric detection is useful for bioimaging because redox species are not consumed or produced during the detection process; therefore, there is no effect on cell activity and the detectable signal is sustained. In this study, the potentiometer mode of the LSI-based device was applied for the detection of glucose oxidase (GOx) and alkaline phosphatase (ALP) activity. The enzyme activities were quantitatively detected within the concentration ranges of 25-250 μg/mL and 0.10-5.0 ng/mL. In addition, GOx activity in hydrogels and the ALP activity of embryoid bodies (EBs) from embryonic stem (ES) cells were successfully imaged based on detection of the open circuit potentials of individual sensors in real time. To the best of our knowledge, this is the first report of potentiometric imaging using LSI-based electrochemical arrays to detect enzyme activity in ES cells. The LSI-based device is thus demonstrated to be a promising tool for bioimaging of enzyme activity.

  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. A new concept for an active element for the large cosmic ray calorimeter ani

    NASA Astrophysics Data System (ADS)

    Lorenz, E.; Borngrebe, S.; Chilingarian, A.; Ferenc, D.; Mirzoyan, R.; Schwarz, R.

    . For the ANI calorimeter (40 x 40 m¡ , 6 concrete absorber layers of 1 m thickness each) at mount Aragatz, Armenia, a cheap and efficient active detector element is needed. One solution is to use long, square tubes (20 x 0.3 x 0.3 m¢ ) filled with wavelength shifter dye doped water. Two PMTs at the ends serve to read out the Cherenkov light generated by fast charged particles. For the crucial light transport along the tubes the walls are lined by a new superreflector foil from 3M (dielectric reflector foil with R £ 98%). From test measurements, a light attenuation of a factor 10-15 over the full length is expected. Due to the high active material fraction of the calorimeter of nearly 15% a good energy and spatial resolution is expected. Prototype results will be presented.

  1. 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.

  2. 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.

  3. 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

  4. HYPATIA and STOIC: an active optics system for a large space telescope

    NASA Astrophysics Data System (ADS)

    Devaney, Nicholas; Reinlein, Claudia; Lange, Nicolas; Goy, Matthias; Goncharov, Alexander; Hallibert, Pascal

    2016-07-01

    The next generation of UVOIR space telescopes will be required to provide excellent wavefront control despite perturbations due to thermal changes, gravity release and vibrations. The STOIC project is a response to an ESA Invitation to Tender to develop an active optics correction chain for future space telescopes. The baseline space telescope being considered is a two-mirror, 4m telescope with a monolithic primary mirror - we refer to this concept as Hypatia. The primary mirror diameter could be extended, but is limited in the near future by launch vehicle dimensions. A deformable mirror (pupil diameter 110mm) will be an integral part of the telescope design; it is being designed for high precision and the ability to maintain a stable form over long periods of time. The secondary mirror of the telescope will be activated to control tip-tilt, defocus and alignment with the primary. Wavefront sensing will be based on phase diversity and a dedicated Shack-Hartmann wavefront sensor. The project will develop a laboratory prototype to demonstrate key aspects of the active correction chain. We present the current state of the preliminary design for both the Hypatia space telescope and the laboratory breadboard.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. ϒ-secretase and LARG mediate distinct RGMa activities to control appropriate layer targeting within the optic tectum

    PubMed Central

    Banerjee, P; Harada, H; Tassew, N G; Charish, J; Goldschneider, D; Wallace, V A; Sugita, S; Mehlen, P; Monnier, P P

    2016-01-01

    While a great deal of progress has been made in understanding the molecular mechanisms that regulate retino-tectal mapping, the determinants that target retinal projections to specific layers of the optic tectum remain elusive. Here we show that two independent RGMa-peptides, C- and N-RGMa, activate two distinct intracellular pathways to regulate axonal growth. C-RGMa utilizes a Leukemia-associated RhoGEF (LARG)/Rho/Rock pathway to inhibit axonal growth. N-RGMa on the other hand relies on ϒ-secretase cleavage of the intracellular portion of Neogenin to generate an intracellular domain (NeICD) that uses LIM-only protein 4 (LMO4) to block growth. In the developing tectum (E18), overexpression of C-RGMa and dominant-negative LARG (LARG-PDZ) induced overshoots in the superficial tectal layer but not in deeper tectal layers. In younger embryos (E12), C-RGMa and LARG-PDZ prevented ectopic projections toward deeper tectal layers, indicating that C-RGMa may act as a barrier to descending axons. In contrast both N-RGMa and NeICD overexpression resulted in aberrant axonal-paths, all of which suggests that it is a repulsive guidance molecule. Thus, two RGMa fragments activate distinct pathways resulting in different axonal responses. These data reveal how retinal projections are targeted to the appropriate layer in their target tissue. PMID:26292756

  10. Activation of CD1d-independent NK1.1+ T cells in the large intestine by Lactobacilli.

    PubMed

    Takahashi, Satoshi; Kawamura, Toshihiko; Kanda, Yasuhiro; Taniguchi, Tomoyo; Nishizawa, Tetsuro; Iiai, Tsuneo; Hatakeyama, Katsuyoshi; Abo, Toru

    2006-01-15

    Among digestive organs, the liver and the large intestine are abundant in T cells expressing NK1.1. NK1.1+ T cells in the liver are mostly CD1d-dependent whereas those in the large intestine are CD1d-independent. In this study, we investigated the effects of Lactobacilli on NK1.1+ T cells in the digestive organs of mice. C57BL/6 mice were orally given a dietary supplement prepared from mixed cultures of eight strains of Lactobacilli. Oral administration of Lactobacilli to mice resulted in the selective expansion of NK1.1+ T cells in the large intestine. These colon NK1.1+ T cells activated by Lactobacilli were found to express IFN-gamma mRNA. The level of IFN-gamma in the serum was also elevated by the administration of Lactobacilli. Our results suggest that Lactobacilli selectively activate CD1d-independent NK1.1+ T cells in the large intestine to produce IFN-gamma and therefore modulate Th1 immune responses.

  11. Large-scale clustering of broad-line Active Galactic Nuclei at low redshifts

    NASA Astrophysics Data System (ADS)

    Krumpe, Mirko; Miyaji, Takamitsu; Coil, Alison; Husemann, Bernd; Fanidakis, Nikolaos; Aceves, Hector

    2015-08-01

    In the last decade, large area surveys (e.g., SDSS, 2dF, XMM-COSMOS) significantly improved AGN clustering measurements, which now provide tight constraints on the mass of the hosting dark matter halos (as a function of AGN luminosity, type, and redshift), the environment in which super massive black hole accretion takes place, and the co-evolution of galaxies and AGN.I will report on a series of papers in which we study the large-scale clustering of broad-line optical and X-ray AGN through cross-correlation measurements with SDSS galaxies. With three independent measurements, we cover a redshift range of z=0.07-0.50. We find an X-ray luminosity dependence in the clustering amplitude of X-ray selected broad-line AGN. X-ray and optically selected broad-line AGN do not show significant differences in the clustering strengths at low redshifts. We apply Halo Occupation Distribution modeling and determined constraints on the distribution of AGN among dark matter halos as a function of their mass. At z~0.3, the AGN fraction decreases with increasing DMH mass. I will also present our newest results on the origin of the X-ray luminosity dependence of broad-line AGN clustering. The mass of supermassive black holes drives the dependence, while no dependence on L/L_EDD is found. Thus, more massive black holes reside in more massive dark matter halos. We also compare our results to state-of-the-art cosmological simulations and find good agreement.

  12. 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

  13. 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%.

  14. 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

  15. Synthesis, characterization and catalytic activity of novel large network polystyrene-immobilized organic bases

    DOE PAGES

    Tassi, Marco; Bartollini, Elena; Adriaensens, Peter; Bianchi, Luca; Barkakaty, Balaka; Carleer, Robert; Chen, Jihua; Hensley, Dale K.; Marrocchi, Assunta; Vaccaro, Luigi

    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.

  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. Optimized mirror supports, active primary mirrors and adaptive secondaries for the Optical Very Large Array (OVLA)

    NASA Astrophysics Data System (ADS)

    Arnold, Luc

    1994-06-01

    This article first deals with general aspects of optimizing mirror supports. A wide variety of support topologies have been optimized by Nelson et al for unobscured entrance pupils. Optical forces and locations of point supports have been calculated here for annular pupils. Efficient topologies introducing a small amount of defocusing are also proposed for unobscured and annular pupils. Support efficiencies are given for each topology. Wavefront errors are estimated in the case of a defective cell, in order to specify tolerances on forces and geometries. The OVLA active optics is then discussed. The very thin, meniscus-shaped primary will be actively supported by 29 actuators and 3 fixed points. Actuator locations and forces have been calculated to minimize the mirror deflection under its own weight but also to allow a good control of astigmatism. We finally present a study of a concave adaptive secondary for the OVLA telescopes. As an initial result, we propose a defocus adaptive corrector with a variable thickness distribution. Conditions of use are defined, and performances are evaluated.

  18. The effect of large aspect ratio wing yaw on active separation control

    NASA Astrophysics Data System (ADS)

    Tewes, Philipp; Taubert, Lutz; Wygnanski, Israel

    2014-11-01

    The applicability of the boundary layer independence principle to turbulent boundary layers developing on infinitely yawed wings, suggested that active separation control might be carried out differently to the two presumably independent developing boundary layers. At low incidence or flap deflection the control of the spanwise component of the flow is effective provided the aggregate number of actuators is small. In this case the actuator jets provide jet-curtains that virtually eliminate the spanwise flow component of the flow in their vicinity. At higher incidence or flap deflection, the focus of the active separation control has to shift to the chordwise component that has to overcome a high adverse pressure gradient. The idea was proven experimentally on a flapped wing based on a NACA 0012 airfoil that could be swept back and forward while being suspended from a ceiling of a wind tunnel connected to a six-component balance. The experiments were carried out at Reynolds numbers varying between 300,000 and 500,000. The project was supported in part by a grant from AFOSR.

  19. 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.

  20. 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. (2013) have introduced a refinement of the method, based on abundance matching of observed galaxies to the Bolshoi dark-matter-only simulation. The EAGLE cosmological hydro-simulation 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. (2013) 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 10^10.75 Msun 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.

  1. Hashing hyperplane queries to near points with applications to large-scale active learning.

    PubMed

    Vijayanarasimhan, Sudheendra; Jain, Prateek; Grauman, Kristen

    2014-02-01

    We consider the problem of retrieving the database points nearest to a given hyperplane query without exhaustively scanning the entire database. For this problem, we propose two hashing-based solutions. Our first approach maps the data to 2-bit binary keys that are locality sensitive for the angle between the hyperplane normal and a database point. Our second approach embeds the data into a vector space where the euclidean norm reflects the desired distance between the original points and hyperplane query. Both use hashing to retrieve near points in sublinear time. Our first method's preprocessing stage is more efficient, while the second has stronger accuracy guarantees. We apply both to pool-based active learning: Taking the current hyperplane classifier as a query, our algorithm identifies those points (approximately) satisfying the well-known minimal distance-to-hyperplane selection criterion. We empirically demonstrate our methods' tradeoffs and show that they make it practical to perform active selection with millions of unlabeled points.

  2. 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

  3. Active structural growth in central Taiwan in relationship to large earthquakes and pore-fluid pressures

    NASA Astrophysics Data System (ADS)

    Yue, Li-Fan

    Central Taiwan is subject to a substantial long-term earthquake risk with a population of five million and two disastrous earthquakes in the last century, the 1935 ML=7.1 Tuntzuchiao and 1999 Mw=7.6 Chi-Chi earthquakes. Rich data from these earthquakes combined with substantial surface and subsurface data accumulated from petroleum exploration form the basis for these studies of the growth of structures in successive large earthquakes and their relationships to pore-fluid pressures. Chapter 1 documents the structural context of the bedding-parallel Chelungpu thrust that slipped in the Chi-Chi earthquake by showing for this richly instrumented earthquake the close geometric relationships between the complex 3D fault shape and the heterogeneous coseismic displacements constrained by geodesy and seismology. Chapter 2 studies the accumulation of deformation by successive large earthquakes by studying the deformation of flights of fluvial terraces deposited over the Chelungpu and adjacent Changhua thrusts, showing the deformation on a timescale of tens of thousands of years. Furthermore these two structures, involving the same stratigraphic sequence, show fundamentally different kinematics of deformation with associated contrasting hanging-wall structural geometries. The heights and shapes of deformed terraces allowed testing of existing theories of fault-related folding. Furthermore terrace dating constrains a combined shortening rate of 37 mm/yr, which is 45% of the total Taiwan plate-tectonic rate, and indicates a substantial earthquake risk for the Changhua thrust. Chapter 3 addresses the long-standing problem of the mechanics of long-thing thrust sheets, such as the Chelungpu and Changhua thrusts in western Taiwan, by presenting a natural test for the classic Hubbert-Rubey hypothesis, which argues that ambient excess pore-fluid pressure substantially reduces the effective fault friction allowing the thrusts to move. Pore-fluid pressure data obtained from 76 wells

  4. Preliminary development of a fiber optic sensor for measuring bilirubin.

    PubMed

    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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. Biaxial flexing of a fiber reinforced aluminum composite

    SciTech Connect

    Tsangarakis, N.; Pepi, M.S. )

    1990-07-01

    A disk specimen of silicon carbide continuous fiber reinforced aluminum is used to study the response of the composite to biaxial tensile flexure. The maximum surface principal tensile strain is constant within a radius of 6.1 mm from the center of the disk. The strain is found to be sensitive to the damage introduced in the composite during flexing. Fiber breakage under monotonic loading is initiated within a fiber tensile strain 0.0038-0.0083. Under cyclic loading and for principal surface strain ranges exceeding 0.0035 the dominant damage mechanism leading to failure is fiber breakage. At smaller surface strain ranges, slip bands and cracks formed in the matrix. The limiting value of the cyclic fiber strain range for a life of one million cycles is 0.00132. This strain is 15 percent of the composite failure strain under uniaxial monotonic loading and 50 percent of the maximum strain in uniaxial tensile fatigue. 27 refs.

  12. 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

  13. 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.

  14. Large-Scale Variational Two-Electron Reduced-Density-Matrix-Driven Complete Active Space Self-Consistent Field Methods.

    PubMed

    Fosso-Tande, Jacob; Nguyen, Truong-Son; Gidofalvi, Gergely; DePrince, A Eugene

    2016-05-10

    A large-scale implementation of the complete active space self-consistent field (CASSCF) method is presented. The active space is described using the variational two-electron reduced-density-matrix (v2RDM) approach, and the algorithm is applicable to much larger active spaces than can be treated using configuration-interaction-driven methods. Density fitting or Cholesky decomposition approximations to the electron repulsion integral tensor allow for the simultaneous optimization of large numbers of external orbitals. We have tested the implementation by evaluating singlet-triplet energy gaps in the linear polyacene series and two dinitrene biradical compounds. For the acene series, we report computations that involve active spaces consisting of as many as 50 electrons in 50 orbitals and the simultaneous optimization of 1892 orbitals. For the dinitrene compounds, we find that the singlet-triplet gaps obtained from v2RDM-driven CASSCF with partial three-electron N-representability conditions agree with those obtained from configuration-interaction-driven approaches to within one-third of 1 kcal mol(-1). When enforcing only the two-electron N-representability conditions, v2RDM-driven CASSCF yields less accurate singlet-triplet energy gaps in these systems, but the quality of the results is still far superior to those obtained from standard single-reference approaches. PMID:27065086

  15. 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.

  16. Broadband standoff detection of large molecules by mid-infrared active coherent laser spectrometry.

    PubMed

    Macleod, Neil A; Molero, Francisco; Weidmann, Damien

    2015-01-26

    A widely tunable active coherent laser spectrometer (ACLaS) has been demonstrated for standoff detection of broadband absorbers in the 1280 to 1318 cm-1 spectral region using an external cavity quantum cascade laser as a mid-infrared source. The broad tuning range allows detection and quantification of vapor phase molecules, such as dichloroethane, ethylene glycol dinitrate, and tetrafluoroethane. The level of confidence in molecular mixing ratios retrieved from interfering spectral measurements is assessed in a quantitative manner. A first qualitative demonstration of condensed phase chemical detection on nitroacetanilide has also been conducted. Detection performances of the broadband ACLaS have been placed in the context of explosive detection and compared to that obtained using distributed feedback quantum cascade lasers.

  17. 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. PMID:19398523

  18. 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

  19. 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.

  20. Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

    NASA Astrophysics Data System (ADS)

    Liu, H.; Richmond, A. D.

    2013-12-01

    In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

  1. Stepwise calibration of the activated sludge model no. 1 at a partially denitrifying large wastewater treatment plant.

    PubMed

    Fall, C; Espinosa-Rodriguez, M A; Flores-Alamo, N; van Loosdrecht, M C M; Hooijmans, C M

    2011-11-01

    Activated sludge modeling technology is maturing; however, currently, there exists a great need to increase its use in daily engineering practice worldwide. A good way for building the capacities of the practitioners is to promote good modeling practices and standardize the protocols. In this study, a systematic procedure was proposed to calibrate the Activated Sludge Model No. 1 (ASM1) at a large wastewater treatment plant, by which the model adequately predicted the quality of the effluent and the sludge quantities. A hydraulics model was set up and validated through a tracer test. The Vesilind settling constants were measured and combined with the default value of the flocculent zone settling parameter, to calibrate the clarifiers. A virtual anoxic tank was installed in the return activated sludge to mimic the denitrification occurring in the settlers. In ASM1, the calibrated parameters were only two influent chemical oxygen demand fractions and one kinetic constant (oxygen half-saturation coefficient).

  2. 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.

  3. 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. PMID:23750905

  4. 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.

  5. Effects of Smoking Intensity and Cessation on Inflammatory Markers in a Large Cohort of Active Smokers

    PubMed Central

    Asthana, Asha; Johnson, Heather M.; Piper, Megan E.; Fiore, Michael C.; Baker, Timothy B.; Stein, James H.

    2010-01-01

    Background Cigarette smoking has been associated with increases in C-reactive protein (CRP) and leukocyte counts (WBC); however, the effects of smoking intensity and smoking cessation on inflammatory markers have not been evaluated prospectively in a large, modern cohort of current smokers. Methods WBC count and high-sensitivity CRP were measured in current smokers enrolled in a randomized, prospective clinical trial of five smoking cessation pharmacotherapies. Smoking intensity parameters included: cigarettes/day, pack-years, Fagerstrom Test of Nicotine Dependence (FTND) score, and carbon monoxide (CO) levels. CRP also was measured after 1 year with assessment of abstinence status. Results The 1,504 current smokers (58% female) were mean (standard deviation): 44.7 (11.1) years old, smoked 21.4 (8.9) cigarettes/day and had a smoking burden of 29.4 (20.4) pack-years. Log (CRP) was not associated with any marker of smoking intensity, except for a weak correlation with pack-years (r=0.05, p=0.047). In contrast, statistically significant correlations were observed between all 4 markers of smoking intensity and WBC count (all p≤0.011). In multivariable models, waist circumference (p<0.001) and triglycerides (p<0.05), but no markers of smoking intensity, were associated with log(CRP). However, pack-years (p=0.002), cigarettes/day (p=0.013), CO (p<0.001), and FTND (p<0.001) were independently associated with WBC count. After 1 year, log(CRP) (p=0.296) and changes in log(CRP) (p=0.455) did not differ between abstainers and continuing smokers. Conclusions Smoking intensity is associated with increased WBC count, but not CRP levels. Smoking cessation does not reduce CRP. The relationship between CRP and smoking intensity may be masked by CRP’s stronger relationship with adiposity. PMID:20826253

  6. 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

  7. 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

  8. 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

  9. 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. PMID:24126286

  10. 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

  11. Solar activity as a possible cause of large forest fires--a case study: analysis of the Portuguese forest fires.

    PubMed

    Gomes, J F P; Radovanovic, M

    2008-05-01

    Fires of large dimension destroy forests, harvests and housing objects. Apart from that combustion products and burned surfaces become large ecological problems. Very often fires emerge simultaneously on different locations of a region so a question could be asked if they always have been a consequence of negligence, pyromania, high temperatures or maybe there has been some other cause. This paper is an attempt of establishing the possible connection between forest fires that numerous satellites registered and activities happening on the Sun immediately before fires ignite. Fires emerged on relatively large areas from Portugal and Spain on August 2005, as well as on other regions of Europe. The cases that have been analyzed show that, in every concrete situation, an emission of strong electromagnetic and thermal corpuscular energy from highly energetic regions that were in geo-effective position had preceded the fires. Such emissions have, usually, very high energy and high speeds of particles and come from coronary holes that also have been either in the very structure or in the immediate closeness of the geo-effective position. It should also be noted that the solar wind directed towards the Earth becomes weaker with deeper penetration towards the topographic surface. However, the results presented in this paper suggest that, there is a strong causality relationship between solar activity and the ignition of these forest fires taking place in South-western Europe.

  12. 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.

  13. 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

  14. Dynamics of the Active Altiplano Puna Magmatic Body: Large-Scale Melt Transport and Buoyant Upwelling

    NASA Astrophysics Data System (ADS)

    Diez, M.; Del Potro, R.

    2014-12-01

    A wide range of geophysical observations suggest that an active partially molten region (Altiplano Puna Magmatic Body or APMB) lies in the mid-upper crust of the Altiplano Puna Plateau, in the Central Andes, with its upper contact at around 20 km depth. In particular, gravity, magnetotellurics and seismics have helped delineating the overall geometry of this intrusive body, which is approximately 200 km in diameter and could be many kilometers thick. The average melt fraction is poorly constrained, although it has been suggested that it could be rather high, around ~15% or higher. In addition to constraining the general shape of the APMB, its dynamics can in principle be partially accessed through geodetic measurements at the surface. In fact, recent InSAR-related studies have shown a ground deformation rate in the order of centimeter per year, with a central uplifting region, centered roughly around a lava-dome complex type of system, Uturuncu volcano, surrounded by an extensive peripheral zone of subsidence. This wealth of observations has leaded us to propose two different hypotheses to partially explain the inner workings of the APMB: (i) the dynamic deformation of the uplift-subsidence of the surface is explained by the impingement of a buoyant melt-rich blob on the more brittle upper levels of the crust, and; (ii) such surface deformation could be associated to the poroviscous compaction induced by lateral melt transport toward a central region of ascent. Both scenarios are modeled numerically. In principle the two hypotheses could explain the rate and geometry of subsidence under some simplifications. We discuss the consequences of both hypotheses, and entertain the possibility of both processes operating together.

  15. 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.

  16. 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.

  17. Large-Scale Active Coronal Phenomena in YOHKOH SXT Images, I

    NASA Astrophysics Data System (ADS)

    Švestka, Zdeněk; Fárník, František; Hudson, Hugh S.; Uchida, Yutaka; Hick, Paul; Lemen, James R.

    1995-11-01

    We have found several occurrences of slowly rising giant arches inYohkoh images. These are similar to the giant post-flare arches previously discovered by SMM instruments in the 80s. However, we see them now with 3 5 times better spatial resolution and can recognize well their loop-like structure. As a rule, these arches followeruptive flares with gradual soft X-ray bursts, and rise with speeds of 1.1 2.4 km s-1 which keep constant for >5 to 24 hours, reaching altitudes up to 250 000 km above the solar limb. These arches differ from post-flare loop systems by their (much higher) altitudes, (much longer) lifetimes, and (constant) speed of growth. One event appears to be a rise of a transequatorial interconnecting loop. In the event of 21 22 February 1992 one can see both the loop system, rising with a gradually decreasing speed to an altitude of 120 000 km, and the arch, emerging from behind the loops and continuing to rise with a constant speed for many more hours up to 240 000 km above the solar limb. In the event of 2 3 November 1991 three subsequent rising large-scale coronal systems can be recognized: first a fast one with speed increasing with altitude and ceasing to be visible at about 300 000 km. This most probably shows the X-ray signature of a coronal mass ejection (CME). A second one, with gradually decreasing speed, might represent very high rising flare loops. A third one continues to rise slowly with a constant speed up to 230 000 km (and up to 285 000 km after the speed begins to decay), and this is the giant arch. This event, including an arch revival on November 4 5, is very similar to rising giant arches observed by the SMM on 6 7 November 1980. Other events of this kind were observed on 27 28 April 1992, 15 March 1993, and 4 6 November 1993, all seen above the solar limb, where it is much easier to identify them. The temperature in the brightest part of the arch of 2 3 November 1991 was increasing with its altitude, from 2 to 4 × 106 K, which

  18. 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.

  19. Endogenous peroxidase activity in brush cell-like cells in the large intestine of the bullfrog tadpole, Rana catesbeiana.

    PubMed

    Sugimoto, K; Ichikawa, Y; Nakamura, I

    1983-01-01

    A special cell type was identified in the mucosal epithelium of the large intestine of the tadpole of the bullfrog, Rana catesbeiana. It is a slender, columnar cell, with a dark, basally situated nucleus. By electron microscopy the cell displays prominent bundles of filaments emerging from each microvillus and extending deep into the cytoplasm without ending in the terminal web. It has longer and more crowded microvilli than the absorptive cell. The specialized cell is also characterized by the presence of many apical vesicles and numerous subapical dense bodies. These cytological features suggest that it may be a brush cell (Rhodin and Dalhamn 1956). These cells displayed endogenous peroxidase activity in smooth and rough endoplasmic reticulum, in the well-developed Golgi apparatus and in apical vesicles. Furthermore, peroxidase reaction product was frequently observed on their luminal surface membrane. These findings suggest that the brush cell in the large intestine of the bullfrog tadpole may be a secretory cell.

  20. Endogenous peroxidase activity in brush cell-like cells in the large intestine of the bullfrog tadpole, Rana catesbeiana.

    PubMed

    Sugimoto, K; Ichikawa, Y; Nakamura, I

    1983-01-01

    A special cell type was identified in the mucosal epithelium of the large intestine of the tadpole of the bullfrog, Rana catesbeiana. It is a slender, columnar cell, with a dark, basally situated nucleus. By electron microscopy the cell displays prominent bundles of filaments emerging from each microvillus and extending deep into the cytoplasm without ending in the terminal web. It has longer and more crowded microvilli than the absorptive cell. The specialized cell is also characterized by the presence of many apical vesicles and numerous subapical dense bodies. These cytological features suggest that it may be a brush cell (Rhodin and Dalhamn 1956). These cells displayed endogenous peroxidase activity in smooth and rough endoplasmic reticulum, in the well-developed Golgi apparatus and in apical vesicles. Furthermore, peroxidase reaction product was frequently observed on their luminal surface membrane. These findings suggest that the brush cell in the large intestine of the bullfrog tadpole may be a secretory cell. PMID:6601990

  1. 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

  2. The Anaplastic Lymphoma Kinase controls cell shape and growth of Anaplastic Large Cell Lymphoma through Cdc42 activation

    PubMed Central

    Ambrogio, Chiara; Voena, Claudia; Manazza, Andrea D.; Martinengo, Cinzia; Costa, Carlotta; Kirchhausen, Tomas; Hirsch, Emilio; Inghirami, Giorgio; Chiarle, Roberto

    2008-01-01

    Anaplastic Large Cell Lymphoma (ALCL) is a Non-Hodgkin Lymphoma (NHL) that originates from T cells and frequently expresses oncogenic fusion proteins derived from chromosomal translocations or inversions of the Anaplastic Lymphoma Kinase (ALK) gene. Proliferation and survival of ALCL cells are determined by the ALK activity. Here we show that the kinase activity of the Nucleophosmin (NPM)-ALK fusion regulated the shape of ALCL cells and F-actin filaments assembly in a pattern similar to T-Cell Receptor (TCR) stimulated cells. NPM-ALK formed a complex with the Guanine Exchange Factor (GEF) VAV1, enhancing its activation through phosphorylation. VAV1 increased Cdc42 activity and, in turn, Cdc42 regulated the shape and the migration of ALCL cells. In vitro knock-down of VAV1 or Cdc42 by sh-RNA, as well as pharmacological inhibition of Cdc42 activity by secramine, resulted in a cell-cycle arrest and apoptosis of ALCL cells. Importantly, the concomitant inhibition of Cdc42 and NPM-ALK kinase acted synergistically to induce apoptosis of ALCL cells. Finally, Cdc42 was necessary for the growth as well as for the maintenance of already established lymphomas in vivo. Thus, our data open perspectives for new therapeutic strategies by revealing a mechanism of regulation of ALCL cells growth through Cdc42. PMID:18974134

  3. 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. PMID:26069324

  4. Activation of muscarinic M3 receptors inhibits large-conductance voltage- and Ca2+-activated K+ channels in rat urinary bladder smooth muscle cells

    PubMed Central

    Parajuli, Shankar P.

    2013-01-01

    Large conductance voltage- and Ca2+-activated K+ (BK) channels are key regulators of detrusor smooth muscle (DSM) contraction and relaxation during urine voiding and storage. Here, we explored whether BK channels are regulated by muscarinic receptors (M-Rs) in native freshly isolated rat DSM cells under physiological conditions using the perforated whole cell patch-clamp technique and pharmacological inhibitors. M-R activation with carbachol (1 μM) initially evoked large transient outward BK currents, followed by inhibition of the spontaneous transient outward BK currents (STBKCs) in DSM cells. Carbachol (1 μM) also inhibited the amplitude and frequency of spontaneous transient hyperpolarizations (STHs) and depolarized the DSM cell membrane potential. Selective inhibition of the muscarinic M3 receptors (M3-Rs) with 4-diphenylacetoxy-N-methylpiperidine (4-DAMP; 0.1 μM), but not muscarinic M2 receptors with methoctramine (1 μM), blocked the carbachol inhibitory effects on STBKCs. Furthermore, blocking the inositol 1,4,5-triphosphate (IP3) receptors with xestospongin-C (1 μM) inhibited the carbachol-induced large transient outward BK currents without affecting carbachol inhibitory effects on STBKCs. Upon pharmacological inhibition of all known cellular sources of Ca2+ for BK channel activation, carbachol (1 μM) did not affect the voltage-step-induced steady-state BK currents, suggesting that the muscarinic effects in DSM cells are mediated by mobilization of intracellular Ca2+. In conclusion, our findings provide strong evidence that activation of M3-Rs leads to inhibition of the STBKCs, STHs, and depolarization of DSM cells. Collectively, the data suggest the existence of functional interactions between BK channels and M3-Rs at a cellular level in DSM. PMID:23703523

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Plasma myeloperoxidase level and polymorphonuclear leukocyte activation in horses suffering from large intestinal obstruction requiring surgery: preliminary results.

    PubMed Central

    Grulke, S; Benbarek, H; Caudron, I; Deby-Dupont, G; Mathy-Hartert, M; Farnir, F; Deby, C; Lamy, M; Serteyn, D

    1999-01-01

    Myeloperoxidase (MPO) is a specific enzyme of neutrophil azurophilic granules with a strong oxidative activity. Thanks to a radioimmunoassay of equine myeloperoxidase, the authors have observed a significantly higher plasma level of MPO in horses operated for strangulation obstruction of the large intestine (n = 6) than in horses suffering from a non-strangulating displacement of the large intestine (n = 9). For the 2 groups, 3 phases were distinguished: reception (P1), intensive care (P2) and terminal phase (P3). The mean peak values of MPO for these phases were 121.6 ng/mL (P1), 168.6 ng/mL (P2), and 107.0 ng/mL (P3) for the non-strangulating group, and 242.6 ng/mL (P1); 426.0 ng/mL (P2), and 379.5 ng/mL (P3) for the strangulation group. The variations of the mean peak values of plasma MPO were significantly different between the 2 groups and between the different phases. A significant increase of the least square means of MPO was observed between P1 and P2. A significant decrease of the least square means of the number of circulating leukocytes was observed between P1 and P3. Polymorphonuclear neutrophil activation could play a major role in the pathogenesis of acute abdominal disease and endotoxic shock. PMID:10369573

  14. A Fiber Bragg Grating Sensing Based Triaxial Vibration Sensor.

    PubMed

    Li, Tianliang; Tan, Yuegang; Liu, Yi; Qu, Yongzhi; Liu, Mingyao; Zhou, Zude

    2015-01-01

    A fiber Bragg grating (FBG) sensing based triaxial vibration sensor has been presented in this paper. The optical fiber is directly employed as elastomer, and the triaxial vibration of a measured body can be obtained by two pairs of FBGs. A model of a triaxial vibration sensor as well as decoupling principles of triaxial vibration and experimental analyses are proposed. Experimental results show that: sensitivities of 86.9 pm/g, 971.8 pm/g and 154.7 pm/g for each orthogonal sensitive direction with linearity are separately 3.64%, 1.50% and 3.01%. The flat frequency ranges reside in 20-200 Hz, 3-20 Hz and 4-50 Hz, respectively; in addition, the resonant frequencies are separately 700 Hz, 40 Hz and 110 Hz in the x/y/z direction. When the sensor is excited in a single direction vibration, the outputs of sensor in the other two directions are consistent with the outputs in the non-working state. Therefore, it is effectively demonstrated that it can be used for three-dimensional vibration measurement. PMID:26393616

  15. A Fiber Bragg Grating Sensing Based Triaxial Vibration Sensor

    PubMed Central

    Li, Tianliang; Tan, Yuegang; Liu, Yi; Qu, Yongzhi; Liu, Mingyao; Zhou, Zude

    2015-01-01

    A fiber Bragg grating (FBG) sensing based triaxial vibration sensor has been presented in this paper. The optical fiber is directly employed as elastomer, and the triaxial vibration of a measured body can be obtained by two pairs of FBGs. A model of a triaxial vibration sensor as well as decoupling principles of triaxial vibration and experimental analyses are proposed. Experimental results show that: sensitivities of 86.9 pm/g, 971.8 pm/g and 154.7 pm/g for each orthogonal sensitive direction with linearity are separately 3.64%, 1.50% and 3.01%. The flat frequency ranges reside in 20–200 Hz, 3–20 Hz and 4–50 Hz, respectively; in addition, the resonant frequencies are separately 700 Hz, 40 Hz and 110 Hz in the x/y/z direction. When the sensor is excited in a single direction vibration, the outputs of sensor in the other two directions are consistent with the outputs in the non-working state. Therefore, it is effectively demonstrated that it can be used for three-dimensional vibration measurement. PMID:26393616

  16. Structural response of a fiber composite compressor fan blade airfoil

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Minich, M. D.

    1975-01-01

    A theoretical investigation was performed to determine the structural response of a fiber composite airfoil typical of those encountered in high-tip speed compressor fan blades when subjected to load conditions anticipated in such applications. The analysis method consisted of composite mechanics embedded in pre- and post-processors coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, and centrifugal. Root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions were investigated. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. The core-shell concept for composite blades is an inefficient design and is sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for the analysis, and to provide quantitative data associated with the various responses which can be helpful in designing composite blades.

  17. Testing of a Fiber Optic Wear, Erosion and Regression Sensor

    NASA Technical Reports Server (NTRS)

    Korman, Valentin; Polzin, Kurt A.

    2011-01-01

    The nature of the physical processes and harsh environments associated with erosion and wear in propulsion environments makes their measurement and real-time rate quantification difficult. A fiber optic sensor capable of determining the wear (regression, erosion, ablation) associated with these environments has been developed and tested in a number of different applications to validate the technique. The sensor consists of two fiber optics that have differing attenuation coefficients and transmit light to detectors. The ratio of the two measured intensities can be correlated to the lengths of the fiber optic lines, and if the fibers and the host parent material in which they are embedded wear at the same rate the remaining length of fiber provides a real-time measure of the wear process. Testing in several disparate situations has been performed, with the data exhibiting excellent qualitative agreement with the theoretical description of the process and when a separate calibrated regression measurement is available good quantitative agreement is obtained as well. The light collected by the fibers can also be used to optically obtain the spectra and measure the internal temperature of the wear layer.

  18. Electroretinography in dogs using a fiber electrode prototype.

    PubMed

    Pereira, A L; Montiani-Ferreira, F; Santos, V R; Salomão, S R; Souza, C; Berezovsky, A

    2013-03-01

    We compared two electroretinography (ERG) electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females) weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype) were used on each animal and the first eye to be recorded (OD × OS) was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

  19. A Fiber Bragg Grating Sensing Based Triaxial Vibration Sensor.

    PubMed

    Li, Tianliang; Tan, Yuegang; Liu, Yi; Qu, Yongzhi; Liu, Mingyao; Zhou, Zude

    2015-09-18

    A fiber Bragg grating (FBG) sensing based triaxial vibration sensor has been presented in this paper. The optical fiber is directly employed as elastomer, and the triaxial vibration of a measured body can be obtained by two pairs of FBGs. A model of a triaxial vibration sensor as well as decoupling principles of triaxial vibration and experimental analyses are proposed. Experimental results show that: sensitivities of 86.9 pm/g, 971.8 pm/g and 154.7 pm/g for each orthogonal sensitive direction with linearity are separately 3.64%, 1.50% and 3.01%. The flat frequency ranges reside in 20-200 Hz, 3-20 Hz and 4-50 Hz, respectively; in addition, the resonant frequencies are separately 700 Hz, 40 Hz and 110 Hz in the x/y/z direction. When the sensor is excited in a single direction vibration, the outputs of sensor in the other two directions are consistent with the outputs in the non-working state. Therefore, it is effectively demonstrated that it can be used for three-dimensional vibration measurement.

  20. A Fiber-Optic Aircraft Lightning Current Measurement Sensor

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

    2013-01-01

    A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

  1. Elastic mid-infrared light scattering: A basis for microscopy of large-scale electrically active defects in semiconducting materials

    NASA Astrophysics Data System (ADS)

    Kalinushkin, V. P.; Yuryev, V. A.; Astafiev, O. V.

    1999-11-01

    A method of the mid-IR-laser microscopy has been recently proposed for the investigation of the large-scale electrically and recombination active defects in semiconductors and nondestructive inspection of semiconductor materials and structures in the industries of microelectronics and photovoltaics. The basis for this development was laid with a wide cycle of the investigations on the low-angle mid-IR-light scattering in semiconductors. The essence of the technical idea was to apply the dark-field method for spatial filtering of the scattered light in the scanning mid-IR-laser microscope. This approach enabled the visualization of large-scale electrically active defects which are the regions enriched with ionized electrically active centers. The photoexcitation of excess carriers within a small volume located in the probe mid-IR-laser beam enabled the visualization of the large-scale recombination-active defects like those revealed in the optical or electron beam induced current methods. Both these methods of the scanning mid-IR-laser microscopy are now introduced in detail in the present article as well as a summary of techniques used in the standard method of the low-angle mid-IR-light scattering itself. Besides the techniques for direct observations, methods for analyses of the defect composition associated with the mid-IR-laser microscopy are also discussed in the article. Special attention is paid upon potential applications of the above methods as characterization and testing techniques in the semiconductor science and industry. It is concluded that elastic midinfrared laser light scattering is a basis for the development of a variety of research techniques and instruments which could be useful in different branches of basic and applied research work in the field of defect engineered semiconductors as well as for the development of devices for quality inspections in the semiconductor industry. Being contactless, nondestructive and nonpolluting, techniques

  2. Multiple types of voltage-dependent Ca2+-activated K+ channels of large conductance in rat brain synaptosomal membranes.

    PubMed Central

    Farley, J.; Rudy, B.

    1988-01-01

    K+-selective ion channels from a mammalian brain synaptosomal membrane preparation were inserted into planar phospholipid bilayers on the tips of patch-clamp pipettes, and single-channel currents were measured. Multiple distinct classes of K+ channels were observed. We have characterized and described the properties of several types of voltage-dependent, Ca2+-activated K+ channels of large single-channel conductance (greater than 50 pS in symmetrical KCl solutions). One class of channels (Type I) has a 200-250-pS single-channel conductance. It is activated by internal calcium concentrations greater than 10(-7) M, and its probability of opening is increased by membrane depolarization. This channel is blocked by 1-3 mM internal concentrations of tetraethylammonium (TEA). These channels are similar to the BK channel described in a variety of tissues. A second novel group of voltage-dependent, Ca2+-activated K+ channels was also studied. These channels were more sensitive to internal calcium, but less sensitive to voltage than the large (Type I) channel. These channels were minimally affected by internal TEA concentrations of 10 mM, but were blocked by a 50 mM concentration. In this class of channels we found a wide range of relatively large unitary channel conductances (65-140 pS). Within this group we have characterized two types (75-80 pS and 120-125 pS) that also differ in gating kinetics. The various types of voltage-dependent, Ca2+-activated K+ channels described here were blocked by charybdotoxin added to the external side of the channel. The activity of these channels was increased by exposure to nanomolar concentrations of the catalytic subunit of cAMP-dependent protein kinase. These results indicate that voltage-dependent, charybdotoxin-sensitive Ca2+-activated K+ channels comprise a class of related, but distinguishable channel types. Although the Ca2+-activated (Type I and II) K+ channels can be distinguished by their single-channel properties, both could

  3. 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.

  4. 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.

  5. Comparison of the applicability domain of a quantitative structure-activity relationship for estrogenicity with a large chemical inventory.

    PubMed

    Netzeva, Tatiana I; Gallegos Saliner, Ana; Worth, Andrew P

    2006-05-01

    The aim of the present study was to illustrate that it is possible and relatively straightforward to compare the domain of applicability of a quantitative structure-activity relationship (QSAR) model in terms of its physicochemical descriptors with a large inventory of chemicals. A training set of 105 chemicals with data for relative estrogenic gene activation, obtained in a recombinant yeast assay, was used to develop the QSAR. A binary classification model for predicting active versus inactive chemicals was developed using classification tree analysis and two descriptors with a clear physicochemical meaning (octanol-water partition coefficient, or log Kow, and the number of hydrogen bond donors, or n(Hdon)). The model demonstrated a high overall accuracy (90.5%), with a sensitivity of 95.9% and a specificity of 78.1%. The robustness of the model was evaluated using the leave-many-out cross-validation technique, whereas the predictivity was assessed using an artificial external test set composed of 12 compounds. The domain of the QSAR training set was compared with the chemical space covered by the European Inventory of Existing Commercial Chemical Substances (EINECS), as incorporated in the CDB-EC software, in the log Kow / n(Hdon) plane. The results showed that the training set and, therefore, the applicability domain of the QSAR model covers a small part of the physicochemical domain of the inventory, even though a simple method for defining the applicability domain (ranges in the descriptor space) was used. However, a large number of compounds are located within the narrow descriptor window.

  6. A very large number of GABAergic neurons are activated in the tuberal hypothalamus during paradoxical (REM) sleep hypersomnia.

    PubMed

    Sapin, Emilie; Bérod, Anne; Léger, Lucienne; Herman, Paul A; Luppi, Pierre-Hervé; Peyron, Christelle

    2010-07-26

    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 GAD(67) 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 GAD(67)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.

  7. Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

    PubMed Central

    Gruda, M C; Zabolotny, J M; Xiao, J H; Davidson, I; Alwine, J C

    1993-01-01

    Simian virus 40 (SV40) large T antigen is a potent transcriptional activator of both viral and cellular promoters. Within the SV40 late promoter, a specific upstream element necessary for T-antigen transcriptional activation is the binding site for transcription-enhancing factor 1 (TEF-1). The promoter structure necessary for T-antigen-mediated transcriptional activation appears to be simple. For example, a promoter consisting of upstream TEF-1 binding sites (or other factor-binding sites) and a downstream TATA or initiator element is efficiently activated. It has been demonstrated that transcriptional activation by T antigen does not require direct binding to the DNA; thus, the most direct effect that T antigen could have on these simple promoters would be through protein-protein interactions with either upstream-bound transcription factors, the basal transcription complex, or both. To determine whether such interactions occur, full-length T antigen or segments of it was fused to the glutathione-binding site (GST fusions) or to the Gal4 DNA-binding domain (amino acids 1 to 147) (Gal4 fusions). With the GST fusions, it was found that TEF-1 and the TATA-binding protein (TBP) bound different regions of T antigen. A GST fusion containing amino acids 5 to 172 (region T1) efficiently bound TBP. TEF-1 bound neither region T1 nor a region between amino acids 168 and 373 (region T2); however, it bound efficiently to the combined region (T5) containing amino acids 5 to 383.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:8423815

  8. Constitutively activated STAT3 promotes cell proliferation and survival in the activated B-cell subtype of diffuse large B-cell lymphomas

    PubMed Central

    Ding, B. Belinda; Yu, J. Jessica; Yu, Raymond Y.-L.; Mendez, Lourdes M.; Shaknovich, Rita; Zhang, Yonghui; Cattoretti, Giorgio

    2008-01-01

    Diffuse large B-cell lymphoma (DLBCL) consists of at least 2 phenotypic subtypes; that is, the germinal center B-cell–like (GCB-DLBCL) and the activated B-cell–like (ABC-DLBCL) groups. It has been shown that GCB-DLBCL responds favorably to chemotherapy and expresses high levels of BCL6, a transcription repressor known to play a causative role in lymphomagenesis. In comparison, ABC-DLBCL has lower levels of BCL6, constitutively activated nuclear factor-κB, and tends to be refractory to chemotherapy. Here, we report that the STAT3 gene is a transcriptional target of BCL6. As a result, high-level STAT3 expression and activation are preferentially detected in ABC-DLBCL and BCL6-negative normal germinal center B cells. Most importantly, inactivating STAT3 by either AG490 or small interference RNA in ABC-DLBCL cells inhibits cell proliferation and triggers apoptosis. These phenotypes are accompanied by decreased expression of several known STAT3 target genes, including c-Myc, JunB, and Mcl-1, and increased expression of the cell- cycle inhibitor p27. In addition to identifying STAT3 as a novel BCL6 target gene, our results define a second oncogenic pathway, STAT3 activation, which operates in ABC-DLBCL, suggesting that STAT3 may be a new therapeutic target in these aggressive lymphomas. PMID:17951530

  9. DS86 neutron dose: Monte Carlo analysis for depth profile of 152Eu activity in a large stone sample.

    PubMed

    Endo, S; Iwatani, K; Oka, T; Hoshi, M; Shizuma, K; Imanaka, T; Takada, J; Fujita, S; Hasai, H

    1999-06-01

    The depth profile of 152Eu activity induced in a large granite stone pillar by Hiroshima atomic bomb neutrons was calculated by a Monte Carlo N-Particle Transport Code (MCNP). The pillar was on the Motoyasu Bridge, located at a distance of 132 m (WSW) from the hypocenter. It was a square column with a horizontal sectional size of 82.5 cm x 82.5 cm and height of 179 cm. Twenty-one cells from the north to south surface at the central height of the column were specified for the calculation and 152Eu activities for each cell were calculated. The incident neutron spectrum was assumed to be the angular fluence data of the Dosimetry System 1986 (DS86). The angular dependence of the spectrum was taken into account by dividing the whole solid angle into twenty-six directions. The calculated depth profile of specific activity did not agree with the measured profile. A discrepancy was found in the absolute values at each depth with a mean multiplication factor of 0.58 and also in the shape of the relative profile. The results indicated that a reassessment of the neutron energy spectrum in DS86 is required for correct dose estimation.

  10. A large family of antivirulence regulators modulates the effects of transcriptional activators in Gram-negative pathogenic bacteria.

    PubMed

    Santiago, Araceli E; Ruiz-Perez, Fernando; Jo, Noah Y; Vijayakumar, Vidhya; Gong, Mei Q; Nataro, James P

    2014-05-01

    We have reported that transcription of a hypothetical small open reading frame (orf60) in enteroaggregative E. coli (EAEC) strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44-100% similarity to at least fifty previously undescribed small (<10 kDa) hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC) repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator) for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators) for this family. PMID:24875828

  11. A Large Family of Antivirulence Regulators Modulates the Effects of Transcriptional Activators in Gram-negative Pathogenic Bacteria

    PubMed Central

    Santiago, Araceli E.; Ruiz-Perez, Fernando; Jo, Noah Y.; Vijayakumar, Vidhya; Gong, Mei Q.; Nataro, James P.

    2014-01-01

    We have reported that transcription of a hypothetical small open reading frame (orf60) in enteroaggregative E. coli (EAEC) strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44–100% similarity to at least fifty previously undescribed small (<10 kDa) hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC) repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator) for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators) for this family. PMID:24875828

  12. 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.

  13. 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

  14. Development of a fiber optic pavement subgrade strain measurement system

    NASA Astrophysics Data System (ADS)

    Miller, Craig Emerson

    2000-11-01

    This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences

  15. Fracture process of a fiber bundle with strong disorder

    NASA Astrophysics Data System (ADS)

    Danku, Zsuzsa; Kun, Ferenc

    2016-07-01

    We investigate the effect of the amount of disorder on the fracture process of heterogeneous materials in the framework of a fiber bundle model. The limit of high disorder is realized by introducing a power law distribution of fiber strength over an infinite range. We show that on decreasing the amount of disorder by controlling the exponent of the power law the system undergoes a transition from the quasi-brittle phase where fracture proceeds in bursts to the phase of perfectly brittle failure where the first fiber breaking triggers a catastrophic collapse. For equal load sharing in the quasi-brittle phase the fat tailed disorder distribution gives rise to a homogeneous fracture process where the sequence of breaking bursts does not show any acceleration as the load increases quasi-statically. The size of bursts is power law distributed with an exponent smaller than the usual mean field exponent of fiber bundles. We demonstrate by means of analytical and numerical calculations that the quasi-brittle to brittle transition is analogous to continuous phase transitions and determine the corresponding critical exponents. When the load sharing is localized to nearest neighbor intact fibers the overall characteristics of the failure process prove to be the same, however, with different critical exponents. We show that in the limit of the highest disorder considered the spatial structure of damage is identical with site percolation—however, approaching the critical point of perfect brittleness spatial correlations play an increasing role, which results in a different cluster structure of failed elements.

  16. Ex vivo bubble production from ovine large blood vessels: size on detachment and evidence of "active spots".

    PubMed

    Arieli, R; Marmur, A

    2014-08-15

    Nanobubbles formed on the hydrophobic silicon wafer were shown to be the source of gas micronuclei from which bubbles evolved during decompression. Bubbles were also formed after decompression on the luminal surface of ovine blood vessels. Four ovine blood vessels: aorta, pulmonary vein, pulmonary artery, and superior vena cava, were compressed to 1013 kPa for 21 h. They were then decompressed, photographed at 1-s intervals, and bubble size was measured on detachment. There were certain spots at which bubbles appeared, either singly or in a cluster. Mean detachment diameter was between 0.7 and 1.0 mm. The finding of active spots at which bubbles nucleate is a new, hitherto unreported observation. It is possible that these are the hydrophobic spots at which bubbles nucleate, stabilise, and later transform into the gas micronuclei that grow into bubbles. The possible neurological effects of these large arterial bubbles should be further explored.

  17. The Radio/Gamma-Ray Connection in Active Galactic Nuclei in the Era of the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Angelakis, E.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Gehrels, N.; Hays, E.; MeEnery, J. E.; Scargle, J. D.; Thompson, D. J.

    2011-01-01

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose.We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the OwensValley RadioObservatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10(exp -7) for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 10(exp -6) to 9.0 10(exp -8). Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10(exp -7)) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

  18. THE RADIO/GAMMA-RAY CONNECTION IN ACTIVE GALACTIC NUCLEI IN THE ERA OF THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Angelakis, E.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Bastieri, D.; Bonamente, E.; Bouvier, A.; Brigida, M.; Bruel, P. E-mail: giroletti@ira.inaf.it

    2011-11-01

    We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose. We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of <10{sup -7} for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 x 10{sup -6} to 9.0 x 10{sup -8}. Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10{sup -7}) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.

  19. Effects of collagen deposition on passive and active mechanical properties of large pulmonary arteries in hypoxic pulmonary hypertension.

    PubMed

    Wang, Zhijie; Lakes, Roderic S; Eickhoff, Jens C; Chesler, Naomi C

    2013-11-01

    Proximal pulmonary artery (PA) stiffening is a strong predictor of mortality in pulmonary hypertension. Collagen accumulation is mainly responsible for PA stiffening in hypoxia-induced pulmonary hypertension (HPH) in mouse models. We hypothesized that collagen cross-linking and the type I isoform are the main determinants of large PA mechanical changes during HPH, which we tested by exposing mice that resist type I collagen degradation (Col1a1[Formula: see text] and littermate controls (Col1a1[Formula: see text] to hypoxia for 10 days with or without [Formula: see text]-aminopropionitrile (BAPN) treatment to prevent cross-link formation. Static and dynamic mechanical tests were performed on isolated PAs with smooth muscle cells (SMC) in passive and active states. Percentages of type I and III collagen were quantified by histology; total collagen content and cross-linking were measured biochemically. In the SMC passive state, for both genotypes, hypoxia tended to increase PA stiffness and damping capacity, and BAPN treatment limited these increases. These changes were correlated with collagen cross-linking ([Formula: see text]). In the SMC active state, hypoxia increased PA dynamic stiffness and BAPN had no effect in Col1a1[Formula: see text] mice ([Formula: see text]). PA stiffness did not change in Col1a1[Formula: see text] mice. Similarly, damping capacity did not change for either genotype. Type I collagen accumulated more in Col1a1[Formula: see text] mice, whereas type III collagen increased more in Col1a1[Formula: see text] mice during HPH. In summary, PA passive mechanical properties (both static and dynamic) are related to collagen cross-linking. Type I collagen turnover is critical to large PA remodeling during HPH when collagen metabolism is not mutated and type III collagen may serve as a reserve. PMID:23377784

  20. Making large class basic histology lectures more interactive: The use of draw-along mapping techniques and associated educational activities.

    PubMed

    Kotzé, Sanet Henriët; Mole, Calvin Gerald

    2015-01-01

    At Stellenbosch University, South Africa, basic histology is taught to a combination class of almost 400 first-year medical, physiotherapy, and dietetic students. Many students often find the amount of work in basic histology lectures overwhelming and consequently loose interest. The aim was to determine if a draw-along mapping activity would focus students during large class lectures. After each lecture on three basic histology tissues, a guided draw-along mapping session covering the work from the lecture was introduced in the form of a click-advance PowerPoint presentation which was used to demonstrate the unfolding of an "ideal" map. The lecturer simultaneously drew a similar map using an overhead projector allowing the students to draw their own maps on blank sheets of paper along with the lecturer. Students remained attentive during the activity and many participated in answering informal questions posed by the lecturer as the map-making session progressed. After the last session, students completed an anonymous, voluntary questionnaire (response rate of 78%). The majority of students found the draw-along maps useful (94%) and believed that its use should be continued in the future (93%). A significant increase (P < 0.001) was found in the test results of student cohorts who were given the current intervention compared to cohorts from previous years who were given mind maps as handouts only or had no intervention. The use of the draw-along mapping sessions were successful in focusing students during large class lectures while also providing them with a useful tool for their studies.

  1. Active learning in a large-enrollment introductory biology class: Problem solving, formative feedback, and teaching as learning

    NASA Astrophysics Data System (ADS)

    Robison, Diane F.

    The purpose of this study was to take a case study approach to exploring student learning experiences in a large enrollment introductory biology class. Traditionally such classes are taught through the lecture method with limited instructor-student interaction and minimal student-centered learning (Lewis & Woodward, 1984; Wulff, Nyqst, & Abbott, 1987). Biology 120 taught at Brigham Young University winter semester 2006 by John Bell was chosen as the case for the study due to its large enrollment (263) and its innovative pedagogy. In the classroom, students applied their learning through a variety of student-centered activities including solving problems, discussing concepts with peers, drawing diagrams, and voting. Outside of the classroom students were assigned, in addition to reading from the textbook and homework problems, to teach each week's concepts to another student. Formative feedback was emphasized in classroom activities and through a unique assessment system. Students took self-graded weekly assessments designed to provide regular and timely feedback on their performance. The only traditionally-graded assessment was the final exam. Students were expected to understand, apply, and think analytically with their knowledge and this was reflected in the assessment items. Student learning, as measured by a pretest and a posttest, increased from an average of 44% correct to 77% correct on a set of 22 items common to both tests. Responses to pre and post-surveys indicated that students increased in their orientation towards understanding as apposed to grades during the course. Qualitative data suggested that during the course many students deepened their learning approach and increased in feelings of personal control over their learning.

  2. Rates of ubiquitin conjugation increase when muscles atrophy, largely through activation of the N-end rule pathway

    NASA Technical Reports Server (NTRS)

    Solomon, V.; Baracos, V.; Sarraf, P.; Goldberg, A. L.

    1998-01-01

    The rapid loss of muscle mass that accompanies many disease states, such as cancer or sepsis, is primarily a result of increased protein breakdown in muscle, and several observations have suggested an activation of the ubiquitin-proteasome system. Accordingly, in extracts of atrophying muscles from tumor-bearing or septic rats, rates of 125I-ubiquitin conjugation to endogenous proteins were found to be higher than in control extracts. On the other hand, in extracts of muscles from hypothyroid rats, where overall proteolysis is reduced below normal, the conjugation of 125I-ubiquitin to soluble proteins decreased by 50%, and treatment with triiodothyronine (T3) restored ubiquitination to control levels. Surprisingly, the N-end rule pathway, which selectively degrades proteins with basic or large hydrophobic N-terminal residues, was found to be responsible for most of these changes in ubiquitin conjugation. Competitive inhibitors of this pathway that specifically block the ubiquitin ligase, E3alpha, suppressed most of the increased ubiquitin conjugation in the muscle extracts from tumor-bearing and septic rats. These inhibitors also suppressed ubiquitination in normal extracts toward levels in hypothyroid extracts, which showed little E3alpha-dependent ubiquitination. Thus, the inhibitors eliminated most of the differences in ubiquitination under these different pathological conditions. Moreover, 125I-lysozyme, a model N-end rule substrate, was ubiquitinated more rapidly in extracts from tumor-bearing and septic rats, and more slowly in those from hypothyroid rats, than in controls. Thus, the rate of ubiquitin conjugation increases in atrophying muscles, and these hormone- and cytokine-dependent responses are in large part due to activation of the N-end rule pathway.

  3. Delivering Science to Large Audiences: Experiments in Active Learning and Public Lectures at the University of Michigan

    NASA Astrophysics Data System (ADS)

    McKay, T.

    1999-12-01

    The problem of disseminating scientific knowledge to the broader community in an effective and efficient way is always with us. At the University of Michigan we have been addressing this problem in several ways. Every year we teach introductory physics to about 3000 students. We believe that, in addition to a pedagogical responsibility, this is an important opportunity for outreach. We report on a variety of approaches to active learning in large lecture classes which are aimed at aiding student comprehension of conceptual material. These have the side affect of improving their general impression of science. In addition to the traditional classroom, we have also engaged in a broader outreach program through the Saturday Morning Physics lecture series, which through a combination of programming and advertising draws audiences of 250 a week to 15 weeks of lectures on topics of current research. We conclude with some general observations about the relation between the success of these public lectures and our large lecture classes. This work is supported by a CAREER award from the National Science Foundation, the University of Michigan, and the Ted Annis Foundation.

  4. Common fragile sites are conserved features of human and mouse chromosomes and relate to large active genes

    PubMed Central

    Helmrich, Anne; Stout-Weider, Karen; Hermann, Klaus; Schrock, Evelin; Heiden, Thomas

    2006-01-01

    Common fragile sites (CFSs) are seen as chromosomal gaps and breaks brought about by inhibition of replication, and it is thought that they cluster with tumor breakpoints. This study presents a comprehensive analysis using conventional and molecular cytogenetic mapping of CFSs and their expression frequencies in two mouse strains, BALB/c and C57BL/6, and in human probands. Here we show that induced mouse CFSs relate to sites of spontaneous gaps and breaks and that CFS expression levels in chromosome bands are conserved between the two mouse strains and between syntenic mouse and human DNA segments. Furthermore, four additional mouse CFSs were found to be homologous to human CFSs on the molecular cytogenetic level (Fra2D-FRA2G, Fra4C2-FRA9E, Fra6A3.1-FRA7G, and Fra6B1-FRA7H), increasing the number of such CFSs already described in the literature to eight. Contrary to previous reports, DNA helix flexibility is not increased in the 15 human and eight mouse CFSs molecularly defined so far, compared to large nonfragile control regions. Our findings suggest that the mechanisms that provoke instability at CFSs are evolutionarily conserved. The role that large transcriptionally active genes may play in CFS expression is discussed. PMID:16954539

  5. Juvenile hormone-dopamine systems for the promotion of flight activity in males of the large carpenter bee Xylocopa appendiculata

    NASA Astrophysics Data System (ADS)

    Sasaki, Ken; Nagao, Takashi

    2013-12-01

    The reproductive roles of dopamine and dopamine regulation systems are known in social hymenopterans, but the knowledge on the regulation systems in solitary species is still needed. To test the possibility that juvenile hormone (JH) and brain dopamine interact to trigger territorial flight behavior in males of a solitary bee species, the effects on biogenic amines of JH analog treatments and behavioral assays with dopamine injections in males of the large carpenter bee Xylocopa appendiculata were quantified. Brain dopamine levels were significantly higher in methoprene-treated males than in control males 4 days after treatment, but were not significantly different after 7 days. Brain octopamine and serotonin levels did not differ between methoprene-treated and control males at 4 and 7 days after treatment. Injection of dopamine caused significantly higher locomotor activities and a shorter duration for flight initiation in experimental versus control males. These results suggest that brain dopamine can be regulated by JH and enhances flight activities in males. The JH-dopamine system in males of this solitary bee species is similar to that of males of the highly eusocial honeybee Apis mellifera.

  6. Juvenile hormone-dopamine systems for the promotion of flight activity in males of the large carpenter bee Xylocopa appendiculata.

    PubMed

    Sasaki, Ken; Nagao, Takashi

    2013-12-01

    The reproductive roles of dopamine and dopamine regulation systems are known in social hymenopterans, but the knowledge on the regulation systems in solitary species is still needed. To test the possibility that juvenile hormone (JH) and brain dopamine interact to trigger territorial flight behavior in males of a solitary bee species, the effects on biogenic amines of JH analog treatments and behavioral assays with dopamine injections in males of the large carpenter bee Xylocopa appendiculata were quantified. Brain dopamine levels were significantly higher in methoprene-treated males than in control males 4 days after treatment, but were not significantly different after 7 days. Brain octopamine and serotonin levels did not differ between methoprene-treated and control males at 4 and 7 days after treatment. Injection of dopamine caused significantly higher locomotor activities and a shorter duration for flight initiation in experimental versus control males. These results suggest that brain dopamine can be regulated by JH and enhances flight activities in males. The JH-dopamine system in males of this solitary bee species is similar to that of males of the highly eusocial honeybee Apis mellifera.

  7. Aberrant immunoglobulin class switch recombination and switch translocations in activated B cell-like diffuse large B cell lymphoma.

    PubMed

    Lenz, Georg; Nagel, Inga; Siebert, Reiner; Roschke, Anna V; Sanger, Warren; Wright, George W; Dave, Sandeep S; Tan, Bruce; Zhao, Hong; Rosenwald, Andreas; Muller-Hermelink, Hans Konrad; Gascoyne, Randy D; Campo, Elias; Jaffe, Elaine S; Smeland, Erlend B; Fisher, Richard I; Kuehl, W Michael; Chan, Wing C; Staudt, Louis M

    2007-03-19

    To elucidate the mechanisms underlying chromosomal translocations in diffuse large B cell lymphoma (DLBCL), we investigated the nature and extent of immunoglobulin class switch recombination (CSR) in these tumors. We used Southern blotting to detect legitimate and illegitimate CSR events in tumor samples of the activated B cell-like (ABC), germinal center B cell-like (GCB), and primary mediastinal B cell lymphoma (PMBL) subgroups of DLBCL. The frequency of legitimate CSR was lower in ABC DLBCL than in GCB DLBCL and PMBL. In contrast, ABC DLBCL had a higher frequency of internal deletions within the switch mu (Smu) region compared with GCB DLBCL and PMBL. ABC DLBCLs also had frequent deletions within Sgamma and other illegitimate switch recombinations. Sequence analysis revealed ongoing Smu deletions within ABC DLBCL tumor clones, which were accompanied by ongoing duplications and activation-induced cytidine deaminase-dependent somatic mutations. Unexpectedly, short fragments derived from multiple chromosomes were interspersed within Smu in one case. These findings suggest that ABC DLBCLs have abnormalities in the regulation of CSR that could predispose to chromosomal translocations. Accordingly, aberrant switch recombination was responsible for translocations in ABC DLBCLs involving BCL6, MYC, and a novel translocation partner, SPIB. PMID:17353367

  8. Aberrant immunoglobulin class switch recombination and switch translocations in activated B cell–like diffuse large B cell lymphoma

    PubMed Central

    Lenz, Georg; Nagel, Inga; Siebert, Reiner; Roschke, Anna V.; Sanger, Warren; Wright, George W.; Dave, Sandeep S.; Tan, Bruce; Zhao, Hong; Rosenwald, Andreas; Muller-Hermelink, Hans Konrad; Gascoyne, Randy D.; Campo, Elias; Jaffe, Elaine S.; Smeland, Erlend B.; Fisher, Richard I.; Kuehl, W. Michael; Chan, Wing C.; Staudt, Louis M.

    2007-01-01

    To elucidate the mechanisms underlying chromosomal translocations in diffuse large B cell lymphoma (DLBCL), we investigated the nature and extent of immunoglobulin class switch recombination (CSR) in these tumors. We used Southern blotting to detect legitimate and illegitimate CSR events in tumor samples of the activated B cell–like (ABC), germinal center B cell–like (GCB), and primary mediastinal B cell lymphoma (PMBL) subgroups of DLBCL. The frequency of legitimate CSR was lower in ABC DLBCL than in GCB DLBCL and PMBL. In contrast, ABC DLBCL had a higher frequency of internal deletions within the switch μ (Sμ) region compared with GCB DLBCL and PMBL. ABC DLBCLs also had frequent deletions within Sγ and other illegitimate switch recombinations. Sequence analysis revealed ongoing Sμ deletions within ABC DLBCL tumor clones, which were accompanied by ongoing duplications and activation-induced cytidine deaminase–dependent somatic mutations. Unexpectedly, short fragments derived from multiple chromosomes were interspersed within Sμ in one case. These findings suggest that ABC DLBCLs have abnormalities in the regulation of CSR that could predispose to chromosomal translocations. Accordingly, aberrant switch recombination was responsible for translocations in ABC DLBCLs involving BCL6, MYC, and a novel translocation partner, SPIB. PMID:17353367

  9. Structural basis for calcium and magnesium regulation of a large conductance calcium-activated potassium channel with β1 subunits.

    PubMed

    Liu, Hao-Wen; Hou, Pan-Pan; Guo, Xi-Ying; Zhao, Zhi-Wen; Hu, Bin; Li, Xia; Wang, Lu-Yang; Ding, Jiu-Ping; Wang, Sheng

    2014-06-13

    Large conductance Ca(2+)- and voltage-activated potassium (BK) channels, composed of pore-forming α subunits and auxiliary β subunits, play important roles in diverse physiological activities. The β1 is predominately expressed in smooth muscle cells, where it greatly enhances the Ca(2+) sensitivity of BK channels for proper regulation of smooth muscle tone. However, the structural basis underlying dynamic interaction between BK mSlo1 α and β1 remains elusive. Using macroscopic ionic current recordings in various Ca(2+) and Mg(2+) concentrations, we identified two binding sites on the cytosolic N terminus of β1, namely the electrostatic enhancing site (mSlo1(K392,R393)-β1(E13,T14)), increasing the calcium sensitivity of BK channels, and the hydrophobic site (mSlo1(L906,L908)-β1(L5,V6,M7)), passing the physical force from the Ca(2+) bowl onto the enhancing site and S6 C-linker. Dynamic binding of these sites affects the interaction between the cytosolic domain and voltage-sensing domain, leading to the reduction of Mg(2+) sensitivity. A comprehensive structural model of the BK(mSlo1 α-β1) complex was reconstructed based on these functional studies, which provides structural and mechanistic insights for understanding BK gating. PMID:24764303

  10. Experiment on large scale plume interaction with a stratified gas environment resembling the thermal activity of a autocatalytic recombiner

    SciTech Connect

    Mignot, G.; Kapulla, R.; Paladino, D.; Zboray, R.

    2012-07-01

    Computational Fluid Dynamics codes (CFD) are increasingly being used to simulate containment conditions after various transient accident scenarios. Consequently, the reliability of such codes must be tested against experimental data. Such validation experiments related to gas mixing and hydrogen transport within containment compartments addressing the effect of heat source are presented in this paper. The experiments were conducted in the large-scale thermal-hydraulics PANDA facility located at the Paul-Scherrer-Inst. (PSI) in Switzerland, in the frame of the OECD/SETH-2 project. A 10 kW electric heater simulating the thermal activity of the autocatalytic recombiner was activated at full power in a containment vessel at the top of which a thick helium layer is initially present. The hot plume interacts with the bottom of the helium layer which is slowly eroded until complete break up at 1350 s. After final erosion of the layer a strong temperature and concentration gradient is maintained in the vessel below the heater inlet as well as in the adjacent vessel below the interconnecting pipe. A detailed characterization of the operating heater suggests the presence of cold gas ingress at the outlet that affects the flow in the chimney. This can be of concern if present in a real PAR unit. (authors)

  11. 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. PMID:22660783

  12. Zolpidem Reduces Hippocampal Neuronal Activity in Freely Behaving Mice: A Large Scale Calcium Imaging Study with Miniaturized Fluorescence Microscope

    PubMed Central

    Berdyyeva, Tamara; Otte, Stephani; Aluisio, Leah; Ziv, Yaniv; Burns, Laurie D.; Dugovic, Christine; Yun, Sujin; Ghosh, Kunal K.; Schnitzer, Mark J.; Lovenberg, Timothy; Bonaventure, Pascal

    2014-01-01

    Therapeutic drugs for cognitive and psychiatric disorders are often characterized by their molecular mechanism of action. Here we demonstrate a new approach to elucidate drug action on large-scale neuronal activity by tracking somatic calcium dynamics in hundreds of CA1 hippocampal neurons of pharmacologically manipulated behaving mice. We used an adeno-associated viral vector to express the calcium sensor GCaMP3 in CA1 pyramidal cells under control of the CaMKII promoter and a miniaturized microscope to observe cellular dynamics. We visualized these dynamics with and without a systemic administration of Zolpidem, a GABAA agonist that is the most commonly prescribed drug for the treatment of insomnia in the United States. Despite growing concerns about the potential adverse effects of Zolpidem on memory and cognition, it remained unclear whether Zolpidem alters neuronal activity in the hippocampus, a brain area critical for cognition and memory. Zolpidem, when delivered at a dose known to induce and prolong sleep, strongly suppressed CA1 calcium signaling. The rate of calcium transients after Zolpidem administration was significantly lower compared to vehicle treatment. To factor out the contribution of changes in locomotor or physiological conditions following Zolpidem treatment, we compared the cellular activity across comparable epochs matched by locomotor and physiological assessments. This analysis revealed significantly depressive effects of Zolpidem regardless of the animal’s state. Individual hippocampal CA1 pyramidal cells differed in their responses to Zolpidem with the majority (∼65%) significantly decreasing the rate of calcium transients, and a small subset (3%) showing an unexpected and significant increase. By linking molecular mechanisms with the dynamics of neural circuitry and behavioral states, this approach has the potential to contribute substantially to the development of new therapeutics for the treatment of CNS disorders. PMID:25372144

  13. Histone deacetylase inhibitors activate CIITA and MHC class II antigen expression in diffuse large B-cell lymphoma

    PubMed Central

    Cycon, Kelly A; Mulvaney, Kathleen; Rimsza, Lisa M; Persky, Daniel; Murphy, Shawn P

    2013-01-01

    Diffuse large B-cell lymphoma (DLBCL), the most common form of non-Hodgkin's lymphoma (NHL) diagnosed in the USA, consists of at least two distinct subtypes: germinal centre B (GCB) and activated B-cell (ABC). Decreased MHC class II (MHCII) expression on the tumours in both DLBCL subtypes directly correlates with significant decreases in patient survival. One common mechanism accounting for MHCII down-regulation in DLBCL is reduced expression of the MHC class II transactivator (CIITA), the master regulator of MHCII transcription. Furthermore, reduced CIITA expression in ABC DLBCL correlates with the presence of the transcriptional repressor positive regulatory domain-I-binding factor-1 (PRDI-BF1). However, the mechanisms underlying down-regulation of CIITA in GCB DLBCL are currently unclear. In this study, we demonstrate that neither PRDI-BF1 nor CpG hypermethylation at the CIITA promoters are responsible for decreased CIITA in GCB DLBCL. In contrast, histone modifications associated with an open chromatin conformation and active transcription were significantly lower at the CIITA promoters in CIITA− GCB cells compared with CIITA+ B cells, which suggests that epigenetic mechanisms contribute to repression of CIITA transcription. Treatment of CIITA− or CIITAlow GCB cells with several different histone deacetylase inhibitors (HDACi) activated modest CIITA and MHCII expression. However, CIITA and MHCII levels were significantly higher in these cells after exposure to the HDAC-1-specific inhibitor MS-275. These results suggest that CIITA transcription is repressed in GCB DLBCL cells through epigenetic mechanisms involving HDACs, and that HDACi treatment can alleviate repression. These observations may have important implications for patient therapy. PMID:23789844

  14. Palmitoylation of the β4-subunit regulates surface expression of large conductance calcium-activated potassium channel splice variants.

    PubMed

    Chen, Lie; Bi, Danlei; Tian, Lijun; McClafferty, Heather; Steeb, Franziska; Ruth, Peter; Knaus, Hans Guenther; Shipston, Michael J

    2013-05-01

    Regulatory β-subunits of large conductance calcium- and voltage-activated potassium (BK) channels play an important role in generating functional diversity and control of cell surface expression of the pore forming α-subunits. However, in contrast to α-subunits, the role of reversible post-translational modification of intracellular residues on β-subunit function is largely unknown. Here we demonstrate that the human β4-subunit is S-acylated (palmitoylated) on a juxtamembrane cysteine residue (Cys-193) in the intracellular C terminus of the regulatory β-subunit. β4-Subunit palmitoylation is important for cell surface expression and endoplasmic reticulum (ER) exit of the β4-subunit alone. Importantly, palmitoylated β4-subunits promote the ER exit and surface expression of the pore-forming α-subunit, whereas β4-subunits that cannot be palmitoylated do not increase ER exit or surface expression of α-subunits. Strikingly, however, this palmitoylation- and β4-dependent enhancement of α-subunit surface expression was only observed in α-subunits that contain a putative trafficking motif (… REVEDEC) at the very C terminus of the α-subunit. Engineering this trafficking motif to other C-terminal α-subunit splice variants results in α-subunits with reduced surface expression that can be rescued by palmitoylated, but not depalmitoylated, β4-subunits. Our data reveal a novel mechanism by which palmitoylated β4-subunit controls surface expression of BK channels through masking of a trafficking motif in the C terminus of the α-subunit. As palmitoylation is dynamic, this mechanism would allow precise control of specific splice variants to the cell surface. Our data provide new insights into how complex interplay between the repertoire of post-transcriptional and post-translational mechanisms controls cell surface expression of BK channels.

  15. pH-activated size reduction of large compound nanoparticles for in vivo nucleus-targeted drug delivery.

    PubMed

    Fan, Yanbin; Li, Chunyan; Li, Fuyou; Chen, Daoyong

    2016-04-01

    Nucleus-targeted drug delivery is a promising strategy for anticancer therapy, but in vivo nucleus-targeted drug delivery has been challenging. Limited by the channel size of the nucleopore, vehicles that enter the nucleus via the nucleopore actively should be small and decorated with nuclear localization signal (NLS). However, the small vehicle size may promote leakage of vehicles into normal tissues, and the positively-charged NLS can lead to strong non-specific interactions in vivo. In the present study, we demonstrate an in vivo nucleus-targeted drug delivery using large compound nanoparticles with detachable PEG shell. The nanoparticles are composed of PEG-benzoic imine-oligo-l-lysine/iridium(III) metallodrug complex and formed in a kinetically-controlled fashion. Under physiological conditions (pH 7.4), the nanoparticles are large (ca. 150 nm) and protected by an inert PEG shell. When internalized into intracellular acidic endo/lysosomes of cancer cells, the nanoparticles dissociate into smaller ones (ca. 40 nm) and the PEG chains detach due to the cleavage of the benzoic imine bond at low pH. The small nanoparticles, with exposure of the oligo-l-lysine after the detachment of the PEG shield, then translocate into the nucleus via the nucleopore due to the small size and nuclear localization ability of the oligo-l-lysine. Importantly, the small particles could significantly release the contained drug into the nucleus, leading to ca. 20-fold higher cytotoxicity compared to the native drug in vitro. Further in vivo application of the nucleus-targeting nano-system in a nude-mice model showed significant tumor inhibition and remarkable life-span elongation. PMID:26854389

  16. Flipped Classroom Modules for Large Enrollment General Chemistry Courses: A Low Barrier Approach to Increase Active Learning and Improve Student Grades

    ERIC Educational Resources Information Center

    Eichler, Jack F.; Peeples, Junelyn

    2016-01-01

    In the face of mounting evidence revealing active learning approaches result in improved student learning outcomes compared to traditional passive lecturing, there is a growing need to change the way instructors teach large introductory science courses. However, a large proportion of STEM faculty continues to use traditional instructor-centered…

  17. Development of GoSlo-SR-5-69, a potent activator of large conductance Ca2+-activated K+ (BK) channels.

    PubMed

    Roy, Subhrangsu; Large, Roddy J; Akande, Adebola Morayo; Kshatri, Aravind; Webb, Tim I; Domene, Carmen; Sergeant, Gerard P; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2014-03-21

    We have designed, synthesised and characterised the effects of a number of novel anthraquinone derivatives and assessed their effects on large conductance, Ca(2+) activated K(+) (BK) channels recorded from rabbit bladder smooth muscle cells using the excised, inside/out configuration of the patch clamp technique. These compounds are members of the GoSlo-SR family of compounds, which potently open BK channels and shift the voltage required for half maximal activation (V1/2) negatively. The efficacy of the anilinoanthraquinone derivatives was enhanced when the size of ring D was increased, since the cyclopentane and cyclohexane derivatives shifted the V1/2, by -24 ± 6 mV and -54 ± 8 mV, respectively, whereas the cycloheptane and cyclooctane derivatives shifted the V1/2 by -61 ± 6 mV and -106 ± 6 mV. To examine if a combination of hydrophobicity and steric bulking of this region further enhanced their ability to open BK channels, we synthesised a number of naphthalene and tetrahydro-naphthalene derivatives. The tetrahydro-2-naphthalene derivative GoSlo-SR-5-69 was the most potent and efficacious of the series since it was able to shift the activation V1/2 by greater than -100 mV when applied at a concentration of 1 μM and had an EC50 of 251 nM, making it one of the most potent and efficacious BK channel openers synthesised to date. PMID:24561672

  18. Giant stellar arcs in the Large Magellanic Cloud: a possible link with past activity of the Milky Way nucleus

    NASA Astrophysics Data System (ADS)

    Efremov, Yuri N.

    2013-02-01

    The origin of the giant stellar arcs in the Large Magellanic Cloud (LMC) remains a controversial issue, one that has been discussed since 1966. No other star/cluster arc is so perfect a segment of a circle; moreover, there is another similar arc nearby. Many hypotheses were advanced to explain these arcs and all but one of these was disproved. It was proposed in 2004 that the origin of these arcs was a bow shock from the jet that is intermittently fired by the Milky Way nucleus; during its last episode of activity the jet was pointed toward the LMC. Quite recently, evidence for such a jet indeed appeared. We suggest that it was once energetic enough to trigger star formation in the LMC, and if the jet opening angle was about 2° then it could push out H i gas from a region of about 2 kpc in size, forming a cavity LMC4, but also squeeze two dense clouds that occurred in the same area, causing the formation of stars along their surfaces facing the core of the Milky Way. As a result, spherical segments of stellar shells might arise, visible now as the arcs named the Quadrant and Sextant, the apexes of which point towards the centre of the Milky Way. The orientation of both arcs could be the key to unlocking their origin. Here we give data that confirm the above hypothesis, amongst which are the radial velocities of stars inside and outside the larger of the LMC arcs. The probability is low that a jet from an active galactic nucleus (AGN) points towards a nearby galaxy and triggers star formation there, but a few other examples are now known or suspected.

  19. Oncogenic activation of the human trk proto-oncogene by recombination with the ribosomal large subunit protein L7a.

    PubMed Central

    Ziemiecki, A; Müller, R G; Fu, X C; Hynes, N E; Kozma, S

    1990-01-01

    The trk-2h oncogene, isolated from the human breast carcinoma cell line MDA-MB 231 by genomic DNA-transfection into NIH3T3 cells, consists of the trk proto-oncogene receptor kinase domain fused to a N-terminal 41 amino acid activating sequence (Kozma, S.C., Redmond, S.M.S., Xiao-Chang, F., Saurer, S.M., Groner, B. and Hynes, N.E. (1988) EMBO J., 7, 147-154). Antibodies raised against a bacterially produced beta gal-trk receptor kinase fusion protein recognized a 44 kd phosphoprotein phosphorylated on serine, threonine and tyrosine in extracts of trk-2h transformed NIH3T3 cells. In vitro, in the presence of Mn2+/gamma ATP, this protein became phosphorylated extensively on tyrosine. Cells transformed by trk-2h did not, however, show an elevation in total phosphotyrosine. We have cloned and sequenced the cDNA encoding the amino terminal activating sequences of trk-2h (Kozma et al., 1988). The encoded protein has a high basic amino acid content and the gene is expressed as an abundant 1.2 kb mRNA in human, rat and mouse cells. Antipeptide antibodies raised against a C-terminal peptide recognized specifically a 30 kd protein on Western blots of human, rat and mouse cell extracts. Immunofluorescence revealed, in addition to granular cytoplasmic fluorescence, intense nucleolar staining. The high basic amino acid content and nucleolar staining prompted us to investigate whether the 30 kd protein could be a ribosomal protein. Western immunoblotting analysis of 2D-electrophoretically resolved ribosomal proteins indicated that the 30 kd protein is the ribosomal large subunit protein L7a.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 9. PMID:2403926

  20. Numerical simulation and experimental validation of the large deformation bending and folding behavior of magneto-active elastomer composites

    NASA Astrophysics Data System (ADS)

    Sheridan, Robert; Roche, Juan; Lofland, Samuel E.; vonLockette, Paris R.

    2014-09-01

    This work seeks to provide a framework for the numerical simulation of magneto-active elastomer (MAE) composite structures for use in origami engineering applications. The emerging field of origami engineering employs folding techniques, an array of crease patterns traditionally on a single flat sheet of paper, to produce structures and devices that perform useful engineering operations. Effective means of numerical simulation offer an efficient way to optimize the crease patterns while coupling to the performance and behavior of the active material. The MAE materials used herein are comprised of nominally 30% v/v, 325 mesh barium hexafarrite particles embedded in Dow HS II silicone elastomer compound. These particulate composites are cured in a magnetic field to produce magneto-elastic solids with anisotropic magnetization, e.g. they have a preferred magnetic axis parallel to the curing axis. The deformed shape and/or blocked force characteristics of these MAEs are examined in three geometries: a monolithic cantilever as well as two- and four-segment composite accordion structures. In the accordion structures, patches of MAE material are bonded to a Gelest OE41 unfilled silicone elastomer substrate. Two methods of simulation, one using the Maxwell stress tensor applied as a traction boundary condition and another employing a minimum energy kinematic (MEK) model, are investigated. Both methods capture actuation due to magnetic torque mechanisms that dominate MAE behavior. Comparison with experimental data show good agreement with only a single adjustable parameter, either an effective constant magnetization of the MAE material in the finite element models (at small and moderate deformations) or an effective modulus in the minimum energy model. The four-segment finite element model was prone to numerical locking at large deformation. The effective magnetization and modulus values required are a fraction of the actual experimentally measured values which suggests a

  1. Leukaemia-associated Rho guanine nucleotide exchange factor (LARG) plays an agonist specific role in platelet function through RhoA activation.

    PubMed

    Zou, Siying; Teixeira, Alexandra M; Yin, Mingzhu; Xiang, Yaozu; Xavier-Ferruccio, Juliana; Zhang, Ping-Xia; Hwa, John; Min, Wang; Krause, Diane S

    2016-08-30

    Leukemia-Associated RhoGEF (LARG) is highly expressed in platelets, which are essential for maintaining normal haemostasis. We studied the function of LARG in murine and human megakaryocytes and platelets with Larg knockout (KO), shRNA-mediated knockdown and small molecule-mediated inhibition. We found that LARG is important for human, but not murine, megakaryocyte maturation. Larg KO mice exhibit macrothrombocytopenia, internal bleeding in the ovaries and prolonged bleeding times. KO platelets have impaired aggregation, α-granule release and integrin α2bβ3 activation in response to thrombin and thromboxane, but not to ADP. The same agonist-specific reductions in platelet aggregation occur in human platelets treated with a LARG inhibitor. Larg KO platelets have reduced RhoA activation and myosin light chain phosphorylation, suggesting that Larg plays an agonist-specific role in platelet signal transduction. Using two different in vivo assays, Larg KO mice are protected from in vivo thrombus formation. Together, these results establish that LARG regulates human megakaryocyte maturation, and is critical for platelet function in both humans and mice. PMID:27345948

  2. A search for pair haloes around active galactic nuclei through a temporal analysis of Fermi-Large Area Telescope data

    NASA Astrophysics Data System (ADS)

    Prokhorov, D. A.; Moraghan, A.

    2016-04-01

    We develop a method to search for pair haloes around active galactic nuclei (AGN) through a temporal analysis of γ-ray data. The basis of our method is an analysis of the spatial distributions of photons coming from AGN flares and from AGN quiescent states and a further comparison of these two spatial distributions. This method can also be used for a reconstruction of a point spread function (PSF). We found no evidence for a pair halo component through this method by applying it to the Fermi-Large Area Telescope (LAT) data in the energy bands of 4.5-6, 6-10, and >10 GeV and set upper limits on the fraction of photons attributable to a pair halo component. An illustration of how to reconstruct the PSF of Fermi-LAT is given. We demonstrate that the PSF reconstructed by using this method is in good agreement with that which was obtained by using the γ-ray data taken by LAT in the direction of the Crab pulsar and nebula.

  3. Energetic ion losses caused by magnetohydrodynamic activity resonant and non-resonant with energetic ions in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Ogawa, Kunihiro; Isobe, Mitsutaka; Toi, Kazuo; Shimizu, Akihiro; Spong, Donald A.; Osakabe, Masaki; Yamamoto, Satoshi; the LHD Experiment Group

    2014-09-01

    Experiments to reveal energetic ion dynamics associated with magnetohydrodynamic activity are ongoing in the Large Helical Device (LHD). Interactions between beam-driven toroidal Alfvén eigenmodes (TAEs) and energetic ions have been investigated. Energetic ion losses induced by beam-driven burst TAEs have been observed using a scintillator-based lost fast-ion probe (SLIP) in neutral beam-heated high β plasmas. The loss flux of co-going beam ions increases as the TAE amplitude increases. In addition to this, the expulsion of beam ions associated with edge-localized modes (ELMs) has been also recognized in LHD. The SLIP has indicated that beam ions having co-going and barely co-going orbits are affected by ELMs. The relation between ELM amplitude and ELM-induced loss has a dispersed structure. To understand the energetic ion loss process, a numerical simulation based on an orbit-following model, DELTA5D, that incorporates magnetic fluctuations is performed. The calculation result shows that energetic ions confined in the interior region are lost due to TAE instability, with a diffusive process characterizing their loss. For the ELM, energetic ions existing near the confinement/loss boundary are lost through a convective process. We found that the ELM-induced loss flux measured by SLIP changes with the ELM phase. This relation between the ELM amplitude and measured ELM-induced loss results in a more dispersed loss structure.

  4. Inhibition of COP9-signalosome (CSN) deneddylating activity and tumor growth of diffuse large B-cell lymphomas by doxycycline

    PubMed Central

    Pulvino, Mary; Chen, Luojing; Oleksyn, David; Li, Jing; Compitello, George; Rossi, Randy; Spence, Stephen; Balakrishnan, Vijaya; Jordan, Craig; Poligone, Brian; Casulo, Carla; Burack, Richard; Shapiro, Joel L.; Bernstein, Steven; Friedberg, Jonathan W.; Deshaies, Raymond J.; Land, Hartmut; Zhao, Jiyong

    2015-01-01

    In searching for small-molecule compounds that inhibit proliferation and survival of diffuse large B-cell lymphoma (DLBCL) cells and may, therefore, be exploited as potential therapeutic agents for this disease, we identified the commonly used and well-tolerated antibiotic doxycycline as a strong candidate. Here, we demonstrate that doxycycline inhibits the growth of DLBCL cells both in vitro and in mouse xenograft models. In addition, we show that doxycycline accumulates in DLBCL cells to high concentrations and affects multiple signaling pathways that are crucial for lymphomagenesis. Our data reveal the deneddylating activity of COP-9 signalosome (CSN) as a novel target of doxycycline and suggest that doxycycline may exert its effects in DLBCL cells in part through a CSN5-HSP90 pathway. Consistently, knockdown of CSN5 exhibited similar effects as doxycycline treatment on DLBCL cell survival and HSP90 chaperone function. In addition to DLBCL cells, doxycycline inhibited growth of several other types of non-Hodgkin lymphoma cells in vitro. Together, our results suggest that doxycycline may represent a promising therapeutic agent for DLBCL and other non-Hodgkin lymphomas subtypes. PMID:26142707

  5. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures.

    PubMed

    Blecha, Kevin A; Alldredge, Mat W

    2015-01-01

    Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor) we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a ground-truthing component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for sources of ground-truthing false-absences can bias the number of predicted feeding events to be low. Thus we account for some ground-truthing error sources directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the ground-truthing false-absence rate is relatively low (4%) using a search delay of 2-60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores.

  6. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures

    PubMed Central

    Blecha, Kevin A.; Alldredge, Mat W.

    2015-01-01

    Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor) we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a ground-truthing component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for sources of ground-truthing false-absences can bias the number of predicted feeding events to be low. Thus we account for some ground-truthing error sources directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the ground-truthing false-absence rate is relatively low (4%) using a search delay of 2–60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores. PMID:26398546

  7. Time evolution of damage due to environmentally assisted aging in a fiber bundle model

    NASA Astrophysics Data System (ADS)

    Lennartz-Sassinek, S.; Main, I. G.; Danku, Z.; Kun, F.

    2013-09-01

    Damage growth in composite materials is a complex process which is of interest in many fields of science and engineering. We consider this problem in a fiber bundle model where fibers undergo an aging process due to the accumulation of damage driven by the locally acting stress in a chemically active environment. By subjecting the bundle to a constant external load, fibers fail either when the load on them exceeds their individual intrinsic strength or when the accumulated internal damage exceeds a random threshold. We analyze the time evolution of the breaking process under low external loads where aging of fibers dominates. In the mean field limit, we show analytically that the aging system continuously accelerates in a way which can be characterized by an inverse power law of the event rate with a singularity that defines a failure time. The exponent is not universal; it depends on the details of the aging process. For localized load sharing, a more complex damage process emerges which is dominated by distinct spatial regions of the system with different degrees of stress concentration. Analytical calculations revealed that the final acceleration to global failure is preceded by a stationary accumulation of damage. When the disorder is strong, the accelerating phase has the same functional behavior as in the mean field limit. The analytical results are verified by computer simulations.

  8. Experimental study of an active grid-generated shearless mixing layer and comparisons with large-eddy simulation

    NASA Astrophysics Data System (ADS)

    Kang, Hyung Suk; Meneveau, Charles

    2008-12-01

    A shearless mixing layer characterized by interactions between two regions with different turbulence intensities but without mean shear is investigated experimentally in a wind tunnel. Reynolds numbers higher than those of prior studies [B. Gilbert, "Diffusion mixing in grid turbulence without mean shear," J. Fluid Mech. 100, 349 (1980); S. Veeravalli and Z. Warhaft, "The shearless turbulent mixing layer," J. Fluid Mech. 207, 191 (1989); B. Knaepen, O. Debliquy, and D. Carati, "Direct numerical simulation and large-eddy simulation of a shear-free mixing layer," J. Fluid Mech. 514, 153 (2004); D. Tordella and M. Iovieno, "Numerical experiments on the intermediate asymptotics of shear-free turbulent transport and diffusion," J. Fluid Mech. 549, 429 (2006); D. A. Briggs, J. H. Ferziger, J. R. Koseff, and S. G. Monismith, "Entrainment in a shear-free turbulent mixing layer," J. Fluid Mech. 310, 215 (1996)] are achieved by using an active grid with rotating winglets on one-half of its cross section. Stationary flow-conditioning fine meshes are used to avoid mean velocity gradients. Measurements are performed at five different downstream wind-tunnel locations using an X-type hot-wire probe and a stereoscopic particle image velocimetry system. The Reynolds numbers based on the Taylor microscale in the high- and low-kinetic energy regions are 170 and 88, respectively. The energy and integral length-scale ratios between the two regions are 4.27 and 1.73, respectively. The inlet turbulence in the upper and lower portions of the shearless mixing layer is not fully isotropic, with the streamwise velocity fluctuations being between 6% and 13% higher than the cross-stream ones. Fundamental statistical properties of the flow are documented and analyzed at various scales using band-pass box-filtered velocities. Downstream evolution of variance and half-width of the mixing layer, skewness and flatness factors, as well as the statistics of two-point velocity increments at various

  9. Continuous, Large-Scale Processing of Seismic Archives for High-Resolution Monitoring of Seismic Activity and Seismogenic Properties

    NASA Astrophysics Data System (ADS)

    Waldhauser, F.; Schaff, D. P.

    2012-12-01

    Archives of digital seismic data recorded by seismometer networks around the world have grown tremendously over the last several decades helped by the deployment of seismic stations and their continued operation within the framework of monitoring earthquake activity and verification of the Nuclear Test-Ban Treaty. We show results from our continuing effort in developing efficient waveform cross-correlation and double-difference analysis methods for the large-scale processing of regional and global seismic archives to improve existing earthquake parameter estimates, detect seismic events with magnitudes below current detection thresholds, and improve real-time monitoring procedures. We demonstrate the performance of these algorithms as applied to the 28-year long seismic archive of the Northern California Seismic Network. The tools enable the computation of periodic updates of a high-resolution earthquake catalog of currently over 500,000 earthquakes using simultaneous double-difference inversions, achieving up to three orders of magnitude resolution improvement over existing hypocenter locations. This catalog, together with associated metadata, form the underlying relational database for a real-time double-difference scheme, DDRT, which rapidly computes high-precision correlation times and hypocenter locations of new events with respect to the background archive (http://ddrt.ldeo.columbia.edu). The DDRT system facilitates near-real-time seismicity analysis, including the ability to search at an unprecedented resolution for spatio-temporal changes in seismogenic properties. In areas with continuously recording stations, we show that a detector built around a scaled cross-correlation function can lower the detection threshold by one magnitude unit compared to the STA/LTA based detector employed at the network. This leads to increased event density, which in turn pushes the resolution capability of our location algorithms. On a global scale, we are currently building

  10. A novel large-conductance Ca(2+)-activated potassium channel and current in nerve terminals of the rat neurohypophysis.

    PubMed Central

    Wang, G; Thorn, P; Lemos, J R

    1992-01-01

    corresponds most closely to a Ca(2+)-activated K+ current (IK(Ca)) and not to a delayed rectifier or IA-like current. It also has properties different from that of the Ca(2+)-dependent outward current described in the magnocellular neuronal cell bodies of the hypothalamus. 8. A large conductance channel is often observed in isolated rat neurohypophysial nerve terminals. The channel had a unit conductance of 231 pS in symmetrical 150 mM K+.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1284313

  11. Process for preparing multilayer enzyme coating on a fiber

    DOEpatents

    Kim, Jungbae; Kwak, Ja Hun; Grate, Jay W.

    2009-11-03

    A process for preparing high stability, high activity biocatalytic materials is disclosed and processes for using the same. The process involves coating of a material or fiber with enzymes and enzyme aggregate providing a material or fiber with high biocatalytic activity and stability useful in heterogeneous environments. In one illustrative approach, enzyme "seeds" are covalently attached to polymer nanofibers followed by treatment with a reagent that crosslinks additional enzyme molecules to the seed enzymes forming enzyme aggregates thereby improving biocatalytic activity due to increased enzyme loading and enzyme stability. This approach creates a useful new biocatalytic immobilized enzyme system with potential applications in bioconversion, bioremediation, biosensors, and biofuel cells.

  12. Submarine hydrothermal activity along the mid-Kermadec Arc, New Zealand: Large-scale effects on venting

    NASA Astrophysics Data System (ADS)

    de Ronde, C. E. J.; Baker, E. T.; Massoth, G. J.; Lupton, J. E.; Wright, I. C.; Sparks, R. J.; Bannister, S. C.; Reyners, M. E.; Walker, S. L.; Greene, R. R.; Ishibashi, J.; Faure, K.; Resing, J. A.; Lebon, G. T.

    2007-07-01

    The 2,500-km Kermadec-Tonga arc is the longest submarine arc on the planet. Here, we report on the second of a series of cruises designed to investigate large-scale controls on active hydrothermal venting on this arc. The 2002 NZAPLUME II cruise surveyed 12 submarine volcanic centers along ~580 km of the middle Kermadec arc (MKA), extending a 1999 cruise that surveyed 260 km of the southern Kermadec arc (SKA). Average spacing between volcanic centers increases northward from 30 km on backarc crust along the SKA, to 45 km on backarc crust along the southern MKA, to 58 km where the MKA joins the Kermadec Ridge. Volcanic cones dominate in the backarc, and calderas dominate the Kermadec Ridge. The incidence of venting is higher along the MKA (83%, 10 of 12 volcanic centers) than the SKA (67%, 8 of 12), but the relative intensity of venting, as given by plume thickness, areal extent, and concentration of dissolved gases and ionic species, is generally weaker in the MKA. This pattern may reflect subduction of the ~17-km-thick oceanic Hikurangi Plateau beneath the SKA. Subduction of this basaltic mass should greatly increase fluid loss from the downgoing slab, initiating extensive melting in the upper mantle wedge and invigorating the hydrothermal systems of the SKA. Conversely, volcanic centers in the southern MKA are starved of magma replenishment and so their hydrothermal systems are waning. Farther north, where the MKA centers merge with the Kermadec Ridge, fewer but larger magma bodies accumulate in the thicker (older) crust, ensuring more widely separated, caldera-dominated volcanic centers.

  13. An integrated approach for monitoring efficiency and investments of activated sludge-based wastewater treatment plants at large spatial scale.

    PubMed

    De Gisi, Sabino; Sabia, Gianpaolo; Casella, Patrizia; Farina, Roberto

    2015-08-01

    WISE, the Water Information System for Europe, is the web-portal of the European Commission (EU) that disseminates the quality state of the receiving water bodies and the efficiency of the municipal wastewater treatment plants (WWTPs) in order to monitor advances in the application of both the Water Framework Directive (WFD) as well as the Urban Wastewater Treatment Directive (UWWTD). With the intention to develop WISE applications, the aim of the work was to define and apply an integrated approach capable of monitoring the efficiency and investments of activated sludge-based WWTPs located in a large spatial area, providing the following outcomes useful to the decision-makers: (i) the identification of critical facilities and their critical processes by means of a Performance Assessment System (PAS), (ii) the choice of the most suitable upgrading actions, through a scenario analysis. (iii) the assessment of the investment costs to upgrade the critical WWTPs and (iv) the prioritization of the critical facilities by means of a multi-criteria approach which includes the stakeholders involvement, along with the integration of some technical, environmental, economic and health aspects. The implementation of the proposed approach to a high number of municipal WWTPs highlighted how the PAS developed was able to identify critical processes with a particular effectiveness in identifying the critical nutrient removal ones. In addition, a simplified approach that considers the cost related to a basic-configuration and those for the WWTP integration, allowed to link the critical processes identified and the investment costs. Finally, the questionnaire for the acquisition of data such as that provided by the Italian Institute of Statistics, the PAS defined and the database on the costs, if properly adapted, may allow for the extension of the integrated approach on an EU-scale by providing useful information to water utilities as well as institutions.

  14. Increased Expression of the Large Conductance, Calcium-Activated K+ (BK) Channel in Adult-Onset Neuronal Ceroid Lipofuscinosis

    PubMed Central

    Donnelier, Julien; Braun, Samuel T.; Dolzhanskaya, Natalia; Ahrendt, Eva; Braun, Andrew P.; Velinov, Milen; Braun, Janice E. A.

    2015-01-01

    Cysteine string protein (CSPα) is a presynaptic J protein co-chaperone that opposes neurodegeneration. Mutations in CSPα (i.e., Leu115 to Arg substitution or deletion (Δ) of Leu116) cause adult neuronal ceroid lipofuscinosis (ANCL), a dominantly inherited neurodegenerative disease. We have previously demonstrated that CSPα limits the expression of large conductance, calcium-activated K+ (BK) channels in neurons, which may impact synaptic excitability and neurotransmission. Here we show by western blot analysis that expression of the pore-forming BKα subunit is elevated ~2.5 fold in the post-mortem cortex of a 36-year-old patient with the Leu116∆ CSPα mutation. Moreover, we find that the increase in BKα subunit level is selective for ANCL and not a general feature of neurodegenerative conditions. While reduced levels of CSPα are found in some postmortem cortex specimens from Alzheimer’s disease patients, we find no concomitant increase in BKα subunit expression in Alzheimer’s specimens. Both CSPα monomer and oligomer expression are reduced in synaptosomes prepared from ANCL cortex compared with control. In a cultured neuronal cell model, CSPα oligomers are short lived. The results of this study indicate that the Leu116∆ mutation leads to elevated BKα subunit levels in human cortex and extend our initial work in rodent models demonstrating the modulation of BKα subunit levels by the same CSPα mutation. While the precise sequence of pathogenic events still remains to be elucidated, our findings suggest that dysregulation of BK channels may contribute to neurodegeneration in ANCL. PMID:25905915

  15. An integrated approach for monitoring efficiency and investments of activated sludge-based wastewater treatment plants at large spatial scale.

    PubMed

    De Gisi, Sabino; Sabia, Gianpaolo; Casella, Patrizia; Farina, Roberto

    2015-08-01

    WISE, the Water Information System for Europe, is the web-portal of the European Commission (EU) that disseminates the quality state of the receiving water bodies and the efficiency of the municipal wastewater treatment plants (WWTPs) in order to monitor advances in the application of both the Water Framework Directive (WFD) as well as the Urban Wastewater Treatment Directive (UWWTD). With the intention to develop WISE applications, the aim of the work was to define and apply an integrated approach capable of monitoring the efficiency and investments of activated sludge-based WWTPs located in a large spatial area, providing the following outcomes useful to the decision-makers: (i) the identification of critical facilities and their critical processes by means of a Performance Assessment System (PAS), (ii) the choice of the most suitable upgrading actions, through a scenario analysis. (iii) the assessment of the investment costs to upgrade the critical WWTPs and (iv) the prioritization of the critical facilities by means of a multi-criteria approach which includes the stakeholders involvement, along with the integration of some technical, environmental, economic and health aspects. The implementation of the proposed approach to a high number of municipal WWTPs highlighted how the PAS developed was able to identify critical processes with a particular effectiveness in identifying the critical nutrient removal ones. In addition, a simplified approach that considers the cost related to a basic-configuration and those for the WWTP integration, allowed to link the critical processes identified and the investment costs. Finally, the questionnaire for the acquisition of data such as that provided by the Italian Institute of Statistics, the PAS defined and the database on the costs, if properly adapted, may allow for the extension of the integrated approach on an EU-scale by providing useful information to water utilities as well as institutions. PMID:25863511

  16. Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device.

    PubMed

    Gläser, Steve; Mede, Ralf; Görls, Helmar; Seupel, Susanne; Bohlender, Carmen; Wyrwa, Ralf; Schirmer, Sina; Dochow, Sebastian; Reddy, Gandra Upendar; Popp, Jürgen; Westerhausen, Matthias; Schiller, Alexander

    2016-08-16

    Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(μ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports. The polylactide non-woven fabric was attached to a fiber optical device. In combination with a laser irradiation source, remote-controlled and light-triggered CO release at 405 nm excitation wavelength was achieved. The device enabled a high flexibility of the spatially and timely defined application of CO with the biocompatible hybrid fabric in aqueous media. The rates of liberated CO were adjusted with the light intensity of the laser. CO release was confirmed via ATR-IR spectroscopy, a portable electrochemical CO sensor and a heterogeneous myoglobin assay.

  17. Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device.

    PubMed

    Gläser, Steve; Mede, Ralf; Görls, Helmar; Seupel, Susanne; Bohlender, Carmen; Wyrwa, Ralf; Schirmer, Sina; Dochow, Sebastian; Reddy, Gandra Upendar; Popp, Jürgen; Westerhausen, Matthias; Schiller, Alexander

    2016-08-16

    Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(μ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports. The polylactide non-woven fabric was attached to a fiber optical device. In combination with a laser irradiation source, remote-controlled and light-triggered CO release at 405 nm excitation wavelength was achieved. The device enabled a high flexibility of the spatially and timely defined application of CO with the biocompatible hybrid fabric in aqueous media. The rates of liberated CO were adjusted with the light intensity of the laser. CO release was confirmed via ATR-IR spectroscopy, a portable electrochemical CO sensor and a heterogeneous myoglobin assay. PMID:27431097

  18. Large area CMOS active pixel sensor x-ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

    SciTech Connect

    Zhao, Chumin; Kanicki, Jerzy; Konstantinidis, Anastasios C.; Patel, Tushita

    2015-11-15

    Purpose: Large area x-ray imagers based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been proposed for various medical imaging applications including digital breast tomosynthesis (DBT). The low electronic noise (50–300 e{sup −}) of CMOS APS x-ray imagers provides a possible route to shrink the pixel pitch to smaller than 75 μm for microcalcification detection and possible reduction of the DBT mean glandular dose (MGD). Methods: In this study, imaging performance of a large area (29 × 23 cm{sup 2}) CMOS APS x-ray imager [Dexela 2923 MAM (PerkinElmer, London)] with a pixel pitch of 75 μm was characterized and modeled. The authors developed a cascaded system model for CMOS APS x-ray imagers using both a broadband x-ray radiation and monochromatic synchrotron radiation. The experimental data including modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE) were theoretically described using the proposed cascaded system model with satisfactory consistency to experimental results. Both high full well and low full well (LFW) modes of the Dexela 2923 MAM CMOS APS x-ray imager were characterized and modeled. The cascaded system analysis results were further used to extract the contrast-to-noise ratio (CNR) for microcalcifications with sizes of 165–400 μm at various MGDs. The impact of electronic noise on CNR was also evaluated. Results: The LFW mode shows better DQE at low air kerma (K{sub a} < 10 μGy) and should be used for DBT. At current DBT applications, air kerma (K{sub a} ∼ 10 μGy, broadband radiation of 28 kVp), DQE of more than 0.7 and ∼0.3 was achieved using the LFW mode at spatial frequency of 0.5 line pairs per millimeter (lp/mm) and Nyquist frequency ∼6.7 lp/mm, respectively. It is shown that microcalcifications of 165–400 μm in size can be resolved using a MGD range of 0.3–1 mGy, respectively. In comparison to a General Electric GEN2 prototype DBT system (at

  19. Piloting a fiber optics and electronic theory curriculum with high school students

    NASA Astrophysics Data System (ADS)

    Gilchrist, Pamela O.; Carpenter, Eric D.; Gray-Battle, Asia

    2014-07-01

    Previous participants from a multi-year blended learning intervention focusing on science, technology, engineering and mathematics (STEM) content knowledge, technical, college, and career preparatory skills were recruited to pilot a new module designed by the project staff. Participants met for a total of 22 contact hours receiving lectures from staff and two guest speakers from industries relevant to photonics, fiber optics hands-on experimentation, and practice with documenting progress. Activities included constructing a fiber optics communication system, troubleshooting breadboard circuits and diagrammed circuits as well as hypothesis testing to discover various aspects of fiber optic cables. Participants documented their activities, wrote reflections on the content and learning endeavor and gave talks about their research experiences to staff, peers, and relatives during the last session. Overall, it was found that a significant gain in content knowledge occurred between the time of pre-testing (Mean=0.54) and post-testing time points for the fiber optics portion of the curriculum via the use of a paired samples t-test (Mean=0.71), t=-2.72, p<.05. Additionally, the electronic theory test results were not a normal distribution and for this reason non-parametric testing was used, specifically a Wilcoxon signed-ranks test. Results indicated a significant increase in content knowledge occurred over time between the pre- (Mdn=0.35) and post-testing time points (Mdn=0.80) z=-2.49, p<,05, r=-0.59 for the electronic theory portion of the curriculum. An equivalent control group was recruited from the remaining participant pool, allowing for comparison between groups. The program design, findings, and lessons learned will be reported in this paper.

  20. Overexpression of the Large-Conductance, Ca2+-Activated K+ (BK) Channel Shortens Action Potential Duration in HL-1 Cardiomyocytes

    PubMed Central

    Stimers, Joseph R.; Song, Li; Rusch, Nancy J.; Rhee, Sung W.

    2015-01-01

    Long QT syndrome is characterized by a prolongation of the interval between the Q wave and the T wave on the electrocardiogram. This abnormality reflects a prolongation of the ventricular action potential caused by a number of genetic mutations or a variety of drugs. Since effective treatments are unavailable, we explored the possibility of using cardiac expression of the large-conductance, Ca2+-activated K+ (BK) channel to shorten action potential duration (APD). We hypothesized that expression of the pore-forming α subunit of human BK channels (hBKα) in HL-1 cells would shorten action potential duration in this mouse atrial cell line. Expression of hBKα had minimal effects on expression levels of other ion channels with the exception of a small but significant reduction in Kv11.1. Patch-clamped hBKα expressing HL-1 cells exhibited an outward voltage- and Ca2+-sensitive K+ current, which was inhibited by the BK channel blocker iberiotoxin (100 nM). This BK current phenotype was not detected in untransfected HL-1 cells or in HL-1 null cells sham-transfected with an empty vector. Importantly, APD in hBKα-expressing HL-1 cells averaged 14.3 ± 2.8 ms (n = 10), which represented a 53% reduction in APD compared to HL-1 null cells lacking BKα expression. APD in the latter cells averaged 31.0 ± 5.1 ms (n = 13). The shortened APD in hBKα-expressing cells was restored to normal duration by 100 nM iberiotoxin, suggesting that a repolarizing K+ current attributed to BK channels accounted for action potential shortening. These findings provide initial proof-of-concept that the introduction of hBKα channels into a cardiac cell line can shorten APD, and raise the possibility that gene-based interventions to increase hBKα channels in cardiac cells may hold promise as a therapeutic strategy for long QT syndrome. PMID:26091273

  1. Past, present, and future concepts in large river ecology: How rivers function and how human activities influence river processes

    SciTech Connect

    Johnson, B.L.; Richardson, W.B.; Naimo, T.J.

    1995-03-01

    This article reviews the current concepts on how flowing water, or lotic, systems function and suggest ways to expand these concepts to increase understanding of large river systems. Topics covered include the following: past and present approaches to physical and biological concepts of stream organization; the river-continuum concept; the flood-pulse concept; deficiencies of the current hypotheses (linear versis hierachical, physical verses biological control, equilibrium versus disequilibrium); future directions for large river research. 63 refs., 4 figs.

  2. Fall Chinook Salmon Spawning Activity Versus Daylight and Flow in the Tailrace of a Large Hydroelectric Dam

    SciTech Connect

    McMichael, Geoffrey A.; McKinstry, Craig A.; Vucelick, Jessica A.; Lukas, Joe

    2005-05-01

    We deployed an acoustic system during the fall Chinook salmon (Oncorhynchus tshawytscha) spawning season in 2001 to determine whether fall Chinook salmon spawning activity in a hydroelectric dam tailrace area was affected by daylight or river flow dynamics. The system was deployed following a randomized study design to record fall Chinook salmon spawning activity during day and night periods in two index areas downstream of Wanapum Dam on the Columbia River in Washington, USA. One index area was a deepwater spawning area located (river kilometer (rkm) 663) in 9 to 11 m of water. The other index site was a moderate depth mid-channel bar, where water depths ranged from 2.5 to 6 m. The acoustic system was used to collect spawning activity data during free-drifts in a boat through the index areas. Spawning activity was defined as digs per minute from underwater sound recordings. Fall Chinook salmon spawning activity in the Wanapum Dam tailrace was influenced by daylight and river discharge. Results showed there was a substantial amount of spawning activity occurring during both daylight and darkness. However, there was significantly more spawning activity during daylight than at night in both index areas. Spawning activity was also affected by flow. Project discharge had a pronounced non-linear effect on spawning activity. Spawning activity was generally highest at project discharges between 1,700 and 2266 m3 sec-1 in both spawning areas, with reduced activity as discharge increased to between 3,400 and 4,250 m3 sec-1. We concluded that fall Chinook salmon spawning activity in highly variable environments was affected more by flow (and velocity) than by daylight.

  3. The Effect of Mechanical Force on Generalized Thermoelasticity in a Fiber-Reinforcement Under Three Theories

    NASA Astrophysics Data System (ADS)

    Othman, Mohamed I. A.; Said, Samia M.

    2012-06-01

    The present paper is concerned with effect of mechanical force on generalized thermoelasticity in a fiber-reinforcement. The formulation is applied to generalized thermoelasticity based on the coupled theory, Lord-Shulman theory, and Green-Lindsay theory. The analytical expression of the displacement components, stresses, and temperature are obtained in the physical domain and illustrated graphically using normal mode analysis. Comparisons are made among the three theories for the field quantities in the absence and in the presence of a fiber-reinforcement as well as for different values of mechanical force.

  4. A fiber optic buckle transducer for measurement of in vitro tendon strain

    NASA Astrophysics Data System (ADS)

    Roriz, Paulo; Ramos, António; Marques, Manuel B.; Simões, José A.; Frazão, Orlando

    2015-09-01

    The purpose of the present study is to present a prototype of a fiber optic based buckle transducer suitable for measuring strain caused by stretching of a tendon. The device has an E-shape and its central arm is instrumented with a fiber Bragg grating (FBG) sensor. The tendon adjusts to the E-form in a fashion that when it is stretched the central arm bends causing a shift of the Bragg's wavelength (λB) that is proportional to the amount of strain. This prototype is presented as an alternative to conventional strain gauge (SG) buckle transducers.

  5. Implementing Distance Teaching at a Large Scale in Medical Education: A Struggle between Dominant and Non-Dominant Teaching Activities

    ERIC Educational Resources Information Center

    Pettersson, Fanny; Olofsson, Anders D.

    2015-01-01

    This paper examines possibilities and challenges when implementing distance teaching of theoretical content in a regionalized medical program (RMP). It will be argued that Cultural-Historical Activity Theory (CHAT) and the concepts of dominant and non-dominant activities, including conflicts and transitional actions, can lead to an understanding…

  6. Construct Validity Evidence for Single-Response Items to Estimate Physical Activity Levels in Large Sample Studies

    ERIC Educational Resources Information Center

    Jackson, Allen W.; Morrow, James R., Jr.; Bowles, Heather R.; FitzGerald, Shannon J.; Blair, Steven N.

    2007-01-01

    Valid measurement of physical activity is important for studying the risks for morbidity and mortality. The purpose of this study was to examine evidence of construct validity of two similar single-response items assessing physical activity via self-report. Both items are based on the stages of change model. The sample was 687 participants (men =…

  7. Interferometric strain measurements with a fiber-optic probe

    NASA Astrophysics Data System (ADS)

    Burnham-Fay, E. D.; Jacobs-Perkins, D. W.; Ellis, J. D.

    2015-09-01

    Experience at the Laboratory for Laser Energetics has shown that broadband base vibrations make it difficult to position cryogenic inertial confinement fusion targets. These effects must be mitigated for National Ignition Facility-scale targets; to this end an active vibration stabilization system is proposed. A single-mode optical fiber strain probe and a novel fiber contained heterodyne interferometer have been developed as a position feedback sensor for the vibration control system. A resolution limit of 54.5 nƐ; is measured with the optical strain gauge, limited by the lock-in amplifier. Experimental measurements of the sensor that show good agreement with reference resistive strain gauge measurements are presented.

  8. Active-Learning Methods To Improve Student Performance and Scientific Interest in a Large Introductory Oceanography Course.

    ERIC Educational Resources Information Center

    Yuretich, Richard F.; Khan, Samia A.; Leckie, R. Mark; Clement, John J.

    2001-01-01

    Transfers the environment of a large enrollment oceanography course by modifying lectures to include cooperative learning via interactive in-class exercises and directed discussion. Results of student surveys, course evaluations, and exam performance demonstrate that learning of the subject under these conditions has improved. (Author/SAH)

  9. [Hygienic assessment of large-size hole type storages for low-to-moderate activity radioactive waste].

    PubMed

    Tkachenko, A V

    2010-01-01

    Analysis of the design features of radioactive waste (RAW) storages of large-size hole type, geological and hydrogeological conditions of their location, a multi-barrier system for environmental protection, and the reliability of a computer-aided geomonitoring system allows one assess these facilities as meeting the current International Atomic Energy Agency recommendations for RAW storages.

  10. Examining the Content of Head Start Teachers' Literacy Instruction within Two Activity Contexts during Large-Group Circle Time

    ERIC Educational Resources Information Center

    Zhang, Chenyi; Diamond, Karen E.; Powell, Douglas R.

    2015-01-01

    Large-group circle time is an important component of many preschool classrooms' daily schedules. This study scrutinized the teaching content of Head Start teachers' literacy instruction (i.e., the types of literacy concept embedded within the instruction, lexical characteristics of teachers' talk, and elaborations on literacy knowledge) in two…

  11. Histamine stimulates the proliferation of small and large cholangiocytes by activation of both IP3/Ca2+ and cAMP-dependent signaling mechanisms

    PubMed Central

    Francis, Heather L; DeMorrow, Sharon; Franchitto, Antonio; Venter, Julie K; Mancinelli, Romina A; White, Mellanie A; Meng, Fanyin; Ueno, Yoshiyuki; Carpino, Guido; Renzi, Anastasia; Baker, Kimberly K; Shine, Hannah E; Francis, Taylor C; Gaudio, Eugenio; Alpini, Gianfranco D; Onori, Paolo

    2012-01-01

    Although large cholangiocytes exert their functions by activation of cyclic adenosine 3′,5′-monophosphate (cAMP), Ca2+-dependent signaling regulates the function of small cholangiocytes. Histamine interacts with four receptors, H1–H4HRs. H1HR acts by Gαq activating IP3/Ca2+, whereas H2HR activates Gαs stimulating cAMP. We hypothesize that histamine increases biliary growth by activating H1HR on small and H2HR on large cholangiocytes. The expression of H1–H4HRs was evaluated in liver sections, isolated and cultured (normal rat intrahepatic cholangiocyte culture (NRIC)) cholangiocytes. In vivo, normal rats were treated with histamine or H1–H4HR agonists for 1 week. We evaluated: (1) intrahepatic bile duct mass (IBDM); (2) the effects of histamine, H1HR or H2HR agonists on NRIC proliferation, IP3 and cAMP levels and PKCα and protein kinase A (PKA) phosphorylation; and (3) PKCα silencing on H1HR-stimulated NRIC proliferation. Small and large cholangiocytes express H1–H4HRs. Histamine and the H1HR agonist increased small IBDM, whereas histamine and the H2HR agonist increased large IBDM. H1HR agonists stimulated IP3 levels, as well as PKCα phosphorylation and NRIC proliferation, whereas H2HR agonists increased cAMP levels, as well as PKA phosphorylation and NRIC proliferation. The H1HR agonist did not increase proliferation in PKCα siRNA-transfected NRICs. The activation of differential signaling mechanisms targeting small and large cholangiocytes is important for repopulation of the biliary epithelium during pathologies affecting different-sized bile ducts. PMID:22064319

  12. Evolution of Magnetic and Velocity Fields in Super-active Region NOAA10486 and the Large 4B/X17.2 Flare of October 28, 2003

    NASA Astrophysics Data System (ADS)

    Ambastha, A.

    2007-08-01

    We have used high cadence GONG + photospheric magnetograms, dopplergrams and Udaipur Solar Observatory (USO) chromospheric Hα-filtergrams to study the spatial and temporal evolution of the active region NOAA 10486 in relation to the X17.2/4B flare of October 28, 2003. New flux emergences, large proper motions and development of steady velocity flows have been identified around the flare site. In addition, filament activation and eruption leading to fast CMEs were noticed. During the flare, NOAA 10486 was located near the disk-center; well suited for the ring diagram analysis. Therefore, we have obtained the 3-D power spectra to search for helioseismic response of the large flare on the amplitude, frequency and width of the p-modes. Power enhancement was found during the post-flare phase, and NOAA 10486 possessed steep gradient in the meridional velocity as compared to the less flare-productive active regions.

  13. Isolated spinach ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase and method of inactivating ribulose-1,5-bisphosphatase carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase activity

    DOEpatents

    Houtz, Robert L.

    1999-01-01

    The gene sequence for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) .sup..epsilon. N-methyltransferase (protein methylase III or Rubisco LSMT) from a plant which has a des(methyl) lysyl residue in the LS is disclosed. In addition, the full-length cDNA clones for Rubisco LSMT are disclosed. Transgenic plants and methods of producing same which have the Rubisco LSMT gene inserted into the DNA are also provided. Further, methods of inactivating the enzymatic activity of Rubisco LSMT are also disclosed.

  14. Characterisation of the large-scale production process of oyster mushroom (Pleurotus ostreatus) with the analysis of succession and spatial heterogeneity of lignocellulolytic enzyme activities.

    PubMed

    Bánfi, Renáta; Pohner, Zsuzsanna; Kovács, József; Luzics, Szabina; Nagy, Adrienn; Dudás, Melinda; Tanos, Péter; Márialigeti, Károly; Vajna, Balázs

    2015-12-01

    Oyster mushroom (Pleurotus ostreatus) lignocellulolytic enzyme activity pattern and variation was investigated in a large-scale facility from spawning until the end of the second flush. In the first cultivation cycle laccase production reached its peak during vegetative growth stage, while manganese-peroxidase showed the highest activity during fruiting body induction. Cellulose and hemicellulose degrading enzymes had maximal activity at the beginning of flush and harvest stage. The enzyme activities showed similar tendencies among five different mushroom substrate blocks representing a production house. The spatial variability analysis of enzyme activities pointed out the within substrate block heterogeneity as the main source if variation. This result was confirmed by Combined Cluster and Discriminant Analysis (CCDA) method showing minimal among block heterogeneity considering the whole investigation period; furthermore in the first cultivation cycle all blocks were grouped into one cluster. PMID:26615756

  15. A fiber-optically coupled positron-sensitive surgical probe

    SciTech Connect

    Raylman, R.R.; Wahl, R.L.

    1994-05-01

    Positron-emitting radiopharmaceuticals such as {sup 18}F-labeled 2-deoxy-D-glucose (FDG) have considerable utility in the noninvasive imaging of cancers due to their rapid and excellent tumor-localizing properties. In addition, the relatively short range of positrons in tissue facilitates the precise delineation of FDG-avid tumors. Therefore, FDG used in conjunction with a positron-sensitive probe may be capable of guiding surgical procedures. Many of the current probe systems, however, are sensitive to the intense flux of background photons produced by positron annihilation. The authors describe the design, manufacture and initial in vitro and in vivo testing of a probe well-suited to the detection of positron-emitting isotopes in a high-photon background. The device consists of a small piece of plastic scintillator coupled by fiber-optic cable to a photomultiplier tube. Measurements of resolution and detector sensitivity were obtained. In addition, the reduction in resolution caused by the effects of various levels of background photon flux was determined. These measurements indicate that resolution is degraded minimally ({approximately}5% with a background-to-source ratio of 2:1) due to annihilation photon background. Sensitivity for positrons is good, detecting amounts of radioactivity as low as 10.2 nCi of FDG in vitro. In rats given FDG subcutaneously, lymph nodes containing as little as 11 nCi of FDG could be detected above the background activity levels present in normal surrounding tissues. A plastic scintillator probe system has been devised which may be highly suitable for intraoperative FDG-guided (or other positron or beta emitting-tracer) surgery. 29 refs., 7 figs.

  16. Using the Langmuir-Schaefer technique to fabricate large-area dense SERS-active Au nanoprism monolayer films.

    PubMed

    Lee, Yih Hong; Lee, Choon Keong; Tan, Baorui; Rui Tan, Joel Ming; Phang, In Yee; Ling, Xing Yi

    2013-07-21

    Interfacial self-assembly of nanoparticles is capable of creating large-area close-packed structures for a variety of applications. However, monolayers of hydrophilic cetyltrimethylammonium bromide (CTAB)-coated Au nanoparticles are challenging to assemble via interfacial self-assembly. This report presents a facile and scalable process to fabricate large-area monolayer films of ultrathin CTAB-coated Au nanoprisms at the air-water interface using the Langmuir-Schaefer technique. This is first achieved by a one-step functionalization of Au nanoprisms with poly(vinylpyrrolidone) (PVP). PVP functionalization is completed within a short time without loss of nanoprisms due to aggregation. Uniform and near close-packed monolayers of the Au nanoprisms formed over large areas (∼1 cm(2)) at the air-water interface can be transferred to substrates with different wettabilities. The inter-prism gaps are tuned qualitatively through the introduction of dodecanethiol and oleylamine. The morphological integrity of the nanoprisms is maintained throughout the entire assembly process, without truncation of the nanoprism tips. The near close-packed arrangement of the nanoprism monolayers generates large numbers of hot spots in the 2D arrays in the tip-to-tip and edge-to-edge inter-particle regions, giving rise to strong surface-enhanced Raman scattering (SERS) signals. When deposited on an Au mirror film, additional hotspots are created in the 3(rd) dimension in the gaps between the 2D nanoprism monolayers and the Au film. SERS enhancement factors reaching 10(4) for non-resonant probe molecules are achieved.

  17. Modeling root-reinforcement with a Fiber-Bundle Model and Monte Carlo simulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper uses sensitivity analysis and a Fiber-Bundle Model (FBM) to examine assumptions underpinning root-reinforcement models. First, different methods for apportioning load between intact roots were investigated. Second, a Monte Carlo approach was used to simulate plants with heartroot, platero...

  18. A fiber-optic retractor for harvesting the internal mammary artery.

    PubMed

    Angelini, G D; Azzu, A A

    1990-08-01

    A retractor for exposure and dissection of the internal mammary artery incorporating a fiber-optic transillumination system is presented. The device, which can be converted to a standard sternal retractor, has also proved valuable in improving illumination during procedures on the mitral valve and in facilitating dissection of fibrous adhesions from the anterior surface of the heart at reoperation.

  19. Dietary grape powder increases IL-1β and IL-6 production by lipopolysaccharide-activated monocytes and reduces plasma concentrations of large LDL and large LDL-cholesterol particles in obese humans.

    PubMed

    Zunino, Susan J; Peerson, Jan M; Freytag, Tammy L; Breksa, Andrew P; Bonnel, Ellen L; Woodhouse, Leslie R; Storms, David H

    2014-08-14

    Obese individuals are at an increased risk of developing CVD, hypertension, type 2 diabetes, and bacterial and viral infections when compared with the normal-weight population. In a 9-week randomised, double-blind, cross-over study, twenty-four obese subjects aged between 20 and 60 years and with a BMI between 30 and 45 kg/m2 were fed grape or placebo powder for 3-week intervals to determine the effects of dietary grapes on blood lipid profiles, plasma inflammatory marker concentrations and immune cell function. Blood samples were collected on days 1 and 8 for obtaining baseline information and at weeks 3, 4, 8 and 9. Comprehensive chemistry panels, lipid profile analyses by NMR, measurement of plasma inflammatory marker concentrations, and analyses of cytokine production by activated T lymphocytes and monocytes were performed for each blood draw. Dietary grape powder reduced the plasma concentrations of large LDL-cholesterol and large LDL particles compared with the placebo powder (P< 0·05). The concentrations of interferon-γ, TNF-α, IL-4 and IL-10 were measured in supernatants from peripheral blood mononuclear cells (PBMC) activated with anti-CD3/CD28 antibodies and those of TNF-α, IL-1β, IL-6 and IL-8 were measured in supernatants from PBMC activated with lipopolysaccharide (LPS). No difference in the production of T-cell cytokines was observed between the two intervention groups. The production of IL-1β and IL-6 was increased in supernatants from LPS-activated PBMC in the grape powder group compared with the placebo powder group (P< 0·05). These data suggest that dietary grapes may decrease atherogenic lipid fractions in obese individuals and increase the sensitivity of monocytes in a population at a greater risk of developing infections.

  20. Uncertainty induced by chest wall thickness assessment methods on lung activity estimation for plutonium and americium: a large population-based study.

    PubMed

    Broggio, D; Lechaftois, X; Franck, D

    2015-03-01

    In vivo lung counting aims at assessing the retained activity in the lungs. The calibration factor relating the measured counts to the worker's specific retained lung activity can be obtained by several means and strongly depends on the chest wall thickness. Here we compare, for 374 male nuclear workers, the activity assessed with a reference protocol, where the material equivalent chest wall thickness is known from ultrasound measurements, with two other protocols. The counting system is an array of four germanium detectors.It is found that non site-specific equations for the assessment of the chest wall thickness induce large biases in the assessment of activity. For plutonium isotopes or (241)Am the proportion of workers for whom the retained activity is within ± 10% of the reference one is smaller than 10%.The use of site-specific equations raises this proportion to 20% and 58% for plutonium and (241)Am, respectively.Finally, for the studied population, when site-specific equations are used for the chest wall thickness, the standard uncertainties for the lung activity are 42% and 12.5%, for plutonium and (241)Am, respectively. Due to the relatively large size of the studied population, these values are a relatively robust estimate of the uncertainties due to the assessment of the chest wall thickness for the current practice at this site. PMID:25517347

  1. Uncertainty induced by chest wall thickness assessment methods on lung activity estimation for plutonium and americium: a large population-based study.

    PubMed

    Broggio, D; Lechaftois, X; Franck, D

    2015-03-01

    In vivo lung counting aims at assessing the retained activity in the lungs. The calibration factor relating the measured counts to the worker's specific retained lung activity can be obtained by several means and strongly depends on the chest wall thickness. Here we compare, for 374 male nuclear workers, the activity assessed with a reference protocol, where the material equivalent chest wall thickness is known from ultrasound measurements, with two other protocols. The counting system is an array of four germanium detectors.It is found that non site-specific equations for the assessment of the chest wall thickness induce large biases in the assessment of activity. For plutonium isotopes or (241)Am the proportion of workers for whom the retained activity is within ± 10% of the reference one is smaller than 10%.The use of site-specific equations raises this proportion to 20% and 58% for plutonium and (241)Am, respectively.Finally, for the studied population, when site-specific equations are used for the chest wall thickness, the standard uncertainties for the lung activity are 42% and 12.5%, for plutonium and (241)Am, respectively. Due to the relatively large size of the studied population, these values are a relatively robust estimate of the uncertainties due to the assessment of the chest wall thickness for the current practice at this site.

  2. Magnetic Evolution of Super-Active Region NOAA AR 10486 and the Large 4B/X17.2 Class Flare Observed During Octbober 28, 2003

    NASA Astrophysics Data System (ADS)

    Ambastha, Ashok

    2005-09-01

    Extensive flare activity was observed in super-active region NOAA10486 during its disk passage of October 22-November 04, 2003. An extremely energetic 4B/X17.2 flare on October 28, 2003/11:10 UT was observed from USO when the active region was located at S16E08, i.e., close to the disk-centre. This flare was rated the third largest X-ray flare recorded by GOES satellite, and the largest in the optical class (4B) observed so far from USO. Chromospheric H-alpha filtergrams were obtained before, during and in the decay phase of the two-ribbon flare at a cadence of 3-4 seconds. The temporal and spatial structure evolution was analyzed with the help of a movie constructed using more than 4000 images. Magnetograms from NASA-MSFC showed large magnetic shear around the flare site which was delineated by a large active filament. The filament erupted as the flare progressed. In the decay phase of the flare, a system of post-flare loops developed at the site of the erupted filament. Observation from TRACE also exhibited these loop structures. Associated with this flare, a fast Earthward moving halo CME was also detected by SOHO, which initiated a major geomagnetic storm on October 29, 2003 at 06:13 UT, i.e., within a record time of 19 hours after the flare. This large flare was followed by another 2B/X11 event on October 29, 2003/20:49 UT, not observed from USO as it occurred in our night-time. We have used white light full disk images and line-of-sight magnetograms obtained from SOHO-MDI for determination of proper motion of the main sunspots and corresponding magnetic fluxes in order to understand rapid magnetic energy build-up in the active region, giving rise to the two large flares within such a short time.

  3. A Novel Active-Learning Protein Purification Exercise for Large-Enrollment Introductory Biochemistry Courses Using the CHROM Web Applet

    ERIC Educational Resources Information Center

    Barrette-Ng, Isabelle H.; Usher, Ken C.

    2013-01-01

    The CHROM Web applet has been used to create a new active-learning exercise in which students design a purification scheme for a recombinant protein using ion-exchange chromatography (IEC). To successfully complete the exercise, students are challenged to apply elementary concepts from acid-base chemistry as well as protein and amino acid…

  4. Making Large Class Basic Histology Lectures More Interactive: The Use of Draw-Along Mapping Techniques and Associated Educational Activities

    ERIC Educational Resources Information Center

    Kotzé, Sanet Henriët; Mole, Calvin Gerald

    2015-01-01

    At Stellenbosch University, South Africa, basic histology is taught to a combination class of almost 400 first-year medical, physiotherapy, and dietetic students. Many students often find the amount of work in basic histology lectures overwhelming and consequently loose interest. The aim was to determine if a draw-along mapping activity would…

  5. Using Active Learning Strategies to Investigate Student Learning and Attitudes in a Large Enrollment, Introductory Geology Course

    ERIC Educational Resources Information Center

    Berry, Stacy Jane

    2013-01-01

    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…

  6. Environmental Characteristics and Student Physical Activity in PE Class: Findings From Two Large Urban Areas of Texas

    PubMed Central

    Skala, Katherine A.; Springer, Andrew E.; Sharma, Shreela V.; Hoelscher, Deanna M.; Kelder, Steven H.

    2011-01-01

    Background Physical education (PE) classes provide opportunities for children to be active. This study examined the associations between specific environmental characteristics (teacher characteristics; class size, duration and location; and lesson context) and elementary school-aged children's moderate-to-vigorous activity (MVPA) during PE. Methods Environmental characteristics and student activity levels were measured in 211 3rd, 4th and 5th grade PE classes in 74 Texas public schools using SOFIT direct observation. Results Students engaged in less than half their PE class time in MVPA (38%), while approximately 25% of class time was spent in classroom management. Percent time in MVPA was significantly higher in outdoor classes compared to indoors (41.4% vs. 36.1%, p=.037). Larger (p=.044) and longer (p=.001) classes were negatively associated with percentage of MVPA and positively correlated with time spent in management (p<.001). Conclusions Findings suggest that children's activity may be influenced by environmental factors such as class size, location, and lesson contexts. These findings hold important policy implications for PE class organization and the need for strategies that maximize children's MVPA. Further research is needed to test the causal association of these factors with student MVPA. PMID:21934165

  7. Host range and cell cycle activation properties of polyomavirus large T-antigen mutants defective in pRB binding

    SciTech Connect

    Freund, R.; Bauer, P.H.; Benjamin, T.L.; Crissman, H.A.; Bradbury, E.M. |

    1994-11-01

    The authors have examined the growth properties of polyomavirus large T-antigen mutants that ar unable to bind pRB, the product of the retinoblastoma tumor suppressor gene. These mutants grow poorly on primary mouse cells yet grow well on NIH 3T3 and other established mouse cell lines. Preinfection of primary baby mouse kidney (BMK) epithelial cells with wild-type simian virus 40 renders these cells permissive to growth of pRB-binding polyomavirus mutants. Conversely, NIH 3T3 cells transfected by and expressing wild-type human pRB become nonpermissive. Primary fibroblasts for mouse embryos that carry a homozygous knockout of the RB gene are permissive, while those from normal littermates are nonpermissive. The host range of polyomavirus pRB-binding mutants is thus determined by expression or lack of expression of functional pRB by the host. These results demonstrate the importance of pRB binding by large T antigen for productive viral infection in primary cells. Failure of pRB-binding mutants to grow well in BMK cells correlates with their failure to induce progression from G{sub 0} or G{sub 1} through the S phase of the cell cycle. Time course studies show delayed synthesis and lower levels of accumulation of large T antigen, viral DNA, and VP1 in mutant compared with wild-type virus-infected BMK cells. These results support a model in which productive infection by polyomavirus in normal mouse cells is tightly coupled to the induction and progression of the cell cycle. 48 refs., 6 figs., 5 tabs.

  8. Active Vibration Control of a Large Flexible Manipulator by Inertial Force and Joint Torque. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Lee, Soo Han

    1988-01-01

    The efficiency and positional accuracy of a lightweight flexible manipulator are limited by its flexural vibrations, which last after a gross motion is completed. The vibration delays subsequent operations. In the proposed work, the vibration is suppressed by inertial force of a small arm in addition to the joint actuators and passive damping treatment. The proposed approach is: (1) Dynamic modeling of a combined system, a large flexible manipulator and a small arm, (2) Determination of optimal sensor location and controller algorithm, and (3) Verification of the fitness of model and the performance of controller.

  9. a Method to Achieve Large Volume, High Accuracy Photogrammetric Measurements Through the Use of AN Actively Deformable Sensor Mounting Platform

    NASA Astrophysics Data System (ADS)

    Sargeant, B.; Robson, S.; Szigeti, E.; Richardson, P.; El-Nounu, A.; Rafla, M.

    2016-06-01

    When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.

  10. Abnormal collagen binding activity of 2A von Willebrand factor: evidence that the defect depends only on the lack of large multimers.

    PubMed

    Casonato, A; Pontara, E; Bertomoro, A; Zucchetto, S; Zerbinati, P; Girolami, A

    1997-02-01

    It is well established that the large von Willebrand factor (vWf) multimers bind with high affinity to the extracellular matrix. To explore the different roles of intermediate and large vWf multimers, we studied the collagen-binding activity (vWf:CBA) of 2A vWf under nonflowing conditions in relation to the multimer organization of the molecule. Regardless of the anticoagulant used for blood collection, vWf:CBA was significantly decreased, in 4 patients with 2A von Willebrand's disease (vWd), in accordance with the lack of high and intermediate vWf multimers. After 1-deamino-8-D-arginine vasopressin (DDAVP) infusion, the appearance of circulating large and unusually large vWf multimers, in samples collected in the presence of protease inhibitors, induced a complete normalization of vWf:CBA. The peak was observed 15 minutes after DDAVP, when large and unusually large multimers were maximally represented. These effects were transient because vWf:CBA decreased after 60 minutes, even though values were still significantly higher than pre-DDAVP figures; at the same time, large vWf multimers appeared to be decreased. In contrast, samples anticoagulated with sodium citrate after DDAVP did not show a normalized vWf multimer pattern and were characterized by a persistently decreased vWf:CBA. Moreover, in all of the patients studied, platelet vWf presented normal vWf:CBA values in accordance with the normal levels and multimer organization of the vWf molecule. Our findings indicate that the collagen-binding defect displayed in vitro by type 2A vWf depends only on the lack of circulating large vWf multimers. Moreover, the observation of normal platelet vWf:CBA seems to indicate a primary role of plasma rather than platelet vWf in assuring platelet plug formation.

  11. Large-scale isolation of flavonolignans from Silybum marianum extract affords new minor constituents and preliminary structure-activity relationships.

    PubMed

    Sy-Cordero, Arlene; Graf, Tyler N; Nakanishi, Yuka; Wani, Mansukh C; Agarwal, Rajesh; Kroll, David J; Oberlies, Nicholas H

    2010-04-01

    The gram-scale isolation of the major flavonolignan diastereoisomers from milk thistle ( Silybum marianum) extract provided an entree into the isolation of two related analogues that are present in extremely minute quantities. The isolation and structure elucidation of these two new compounds, which we have termed isosilybin C and isosilybin D due to their structural similarities to isosilybin A and isosilybin B, respectively, afforded a preliminary analysis of structure-activity relationships toward prostate cancer growth, survival, and apoptotic endpoints.

  12. STAT3 activation is associated with cerebrospinal fluid interleukin-10 (IL-10) in primary central nervous system diffuse large B cell lymphoma.

    PubMed

    Mizowaki, Takashi; Sasayama, Takashi; Tanaka, Kazuhiro; Mizukawa, Katsu; Takata, Kumi; Nakamizo, Satoshi; Tanaka, Hirotomo; Nagashima, Hiroaki; Nishihara, Masamitsu; Hirose, Takanori; Itoh, Tomoo; Kohmura, Eiji

    2015-09-01

    Signal transducers and activators of transcription 3 (STAT3) are activated by various cytokines and oncogenes; however, the activity and pathogenesis of STAT3 in diffuse large B cell lymphoma of the central nervous system have not been thoroughly elucidated. We investigated the phosphorylation levels of STAT3 in 40 specimens of primary central nervous system diffuse large B-cell lymphoma (PCNS DLBCL) and analyzed the association between phsopho-STAT3 (pSTAT3) expression and cerebrospinal fluid (CSF) concentration of interleukin-10 (IL-10) or IL-6. Immunohistochemistry and Western blot analysis revealed that most of the specimens in PCNS DLBCL expressed pSTST3 protein, and a strong phosphorylation levels of STAT3 was statistically associated with high CSF IL-10 levels, but not with CSF IL-6 levels. Next, we demonstrated that recombinant IL-10 and CSF containing IL-10 induced the phosphorylation of STAT3 in PCNS DLBCL cells. Furthermore, molecular subtype classified by Hans' algorithm was correlated with pSTAT3 expression levels and CSF IL-10 levels. These results suggest that the STAT3 activity is correlated with CSF IL-10 level, which is a useful marker for STAT3 activity in PCNS DLBCLs.

  13. The expression and activity of 5-LOX in the large intestine of horses harbouring encysted cyathostomin larvae.

    PubMed

    Giacominelli-Stuffler, Roberto; Frangipane di Regalbono, Antonio; Traversa, Donato; Geurden, Thomas; Marcer, Federica; Di Francesco, Andrea; Angelini, Chiara; di Cesare, Angela; Storelli, Maria Maddalena; Maccarrone, Mauro

    2014-06-16

    Leukotrienes are products of the arachidonic acid metabolism and act as potent inflammatory mediators modulating the immune response and various physiological processes. This study evaluated the expression and activity of 5-lipoxygenase (5-LOX), the enzyme that catalyzes the first two steps in the biosynthesis of leukotrienes, in horses infected by larval cyathostomins. Tissue samples from dorsal and ventral colon, and from the cecum were collected from 16 horses slaughtered for human consumption. Samples were analyzed to estimate the burdens of encysted cyathostomin larvae and adult luminal stages, and then processed for the evaluation of biochemical parameters. No significant differences were found in the protein expression and enzymatic activity of 5-LOX between animals harbouring only adult parasites and negative horses. The protein expression and enzyme activity of 5-LOX were significantly higher in horses harbouring encysted larvae in comparison with horses free of encysted larvae. Although preliminary, these results indicate that 5-LOX is an important mediator in the course of horse cyathostominosis and further studies are warranted to unveil the possible role this enzyme plays in the pathogenesis of horse cyathostominosis, and its potential as a diagnostic marker.

  14. The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity.

    PubMed

    Bourbouli, Maria; Katsifas, Efstathios A; Papathanassiou, Evangelos; Karagouni, Amalia D

    2015-05-01

    Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds.

  15. The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity.

    PubMed

    Bourbouli, Maria; Katsifas, Efstathios A; Papathanassiou, Evangelos; Karagouni, Amalia D

    2015-05-01

    Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds. PMID:25627249

  16. The Martian hydrologic system: Multiple recharge centers at large volcanic provinces and the contribution of snowmelt to outflow channel activity

    NASA Astrophysics Data System (ADS)

    Russell, Patrick S.; Head, James W.

    2007-02-01

    Global recharge of the martian hydrologic system has traditionally been viewed as occurring through basal melting of the south polar cap. We conclude that regional recharge of a groundwater system at the large volcanic provinces, Elysium and Tharsis, is also very plausible and has several advantages over a south polar recharge source in providing a more direct, efficient supply of water to the outflow channel source regions surrounding these areas. This recharge scenario is proposed to have operated concurrently with and within the context of a global cryosphere-hydrosphere system of the subsurface characteristic of post-Noachian periods. To complement existing groundwater flow modeling studies, we examine geologic evidence and possible mechanisms for accumulation of water at high elevations on the volcanic rises, such as melting snow, infiltration, and increased effective permeability of the subsurface between the recharge zone and outflow source. Evidence for the presence of large Amazonian-aged cold-based piedmont glaciers on the Tharsis Montes has been well documented. Climate modeling predicts snow accumulation on high volcanic rises at obliquities thought to be typical over much of martian history. Thermal gradients causing basal melting of snowpack over 1 km thick could provide several kg m -2 yr -1 of water, charging a volume equivalent to the pore space in a square meter column of subsurface in less than 1.5×10 5 yr. In order to account for estimated outflow channel volumes, the subsurface volume above the elevation of the outflow channels must be charged several times over the area of Tharsis. Complete aquifer recharge can be accomplished in ˜0.3-2 My through the snowpack melting mechanism at Tharsis and in ˜5×10 4 years for channel requirements at Elysium. Abundant radial dikes emanating from large martian volcanic rises can crack and/or melt the cryosphere, initiating water outflow and creating anisotropies that can channel subsurface water from a

  17. Optical and Radar Satellite Remote Sensing for Large Area Analysis of Landslide Activity in Southern Kyrgyzstan, Central Asia

    NASA Astrophysics Data System (ADS)

    Roessner, S.; Behling, R.; Teshebaeva, K. O.; Motagh, M.; Wetzel, H. U.

    2014-12-01

    The presented work has been investigating the potential of optical and radar satellite remote sensing for the spatio-temporal analysis of landslide activity at a regional scale along the eastern rim of the Fergana Basin representing the area of highest landslide activity in Kyrgyzstan. For this purpose a multi-temporal satellite remote sensing database has been established for a 12.000 km2 study area in Southern Kyrgyzstan containing a multitude of optical data acquired during the last 28 years as well as TerraSAR-X and ALOS-PALSAR acquired since 2007. The optical data have been mainly used for creating a multi-temporal inventory of backdated landslide activity. For this purpose an automated approach for object-oriented multi-temporal landslide detection has been developed which is based on the analysis of temporal NDVI-trajectories complemented by relief information to separate landslide-related surface changes from other land cover changes. Applying the approach to the whole study area using temporal high resolution RapidEye time series data has resulted in the automated detection of 612 landslide objects covering a total area of approx. 7.3 km². Currently, the approach is extended to the whole multi-sensor time-series database for systematic analysis of longer-term landslide occurrence at a regional scale. Radar remote sensing has been focussing on SAR Interferometry (InSAR) to detect landslide related surface deformation. InSAR data were processed by repeat-pass interferometry using the DORIS and SARScape software. To better assess ground deformation related to individual landslide objects, InSAR time-series analysis has been applied using the Small Baseline Subset (SBAS) method. Analysis of the results in combination with optical data and DEM information has revealed that most of the derived deformations are caused by slow movements in areas of already existing landslides indicating the reactivation of older slope failures. This way, InSAR analysis can

  18. Analysis and interpretation of CCD data on P/Halley and physical parameters and activity status of cometary nuclei at large heliocentric distance

    NASA Technical Reports Server (NTRS)

    Belton, Michael J. S.; Mueller, Beatrice

    1991-01-01

    The scientific objectives were as follows: (1) to construct a well sampled photometric time series of comet Halley extending to large heliocentric distances both post and pre-perihelion passage and derive a precise ephemeris for the nuclear spin so that the physical and chemical characteristics of individual regions of activity on the nucleus can be determined; and (2) to extend the techniques in the study of Comet Halley to the study of other cometary nuclei and to obtain new observational data.

  19. Observations of large-scale plasma convection in the magnetosphere with respect to the geomagnetic activity level

    NASA Astrophysics Data System (ADS)

    Stepanov, A. E.; Khalipov, V. L.; Kotova, G. A.; Zabolotskii, M. S.; Golikov, I. A.

    2016-03-01

    The data of the ionospheric observations (the daily f plots) at the Yakutsk meridional chain of ionosondes (Yakutsk-Zhigansk-Batagai-Tixie Bay) with sharp decreases (breaks) in the critical frequency of the regular ionospheric F2 layer ( foF2) are considered. The data for 1968-1983 were analyzed, and the statistics of the foF2 break observations, which indicate that these breaks are mainly registered in equinoctial months and in afternoon and evening hours under moderately disturbed geomagnetic conditions, are presented. Calculations performed using the prognostic model of the high-latitude ionosphere indicate that the critical frequency break position coincides with the equatorial boundary of large-scale plasma convection in the dusk MLT sector.

  20. CERN-RD39 collaboration activities aimed at cryogenic silicon detector application in high-luminosity Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Eremin, Vladimir; Verbitskaya, Elena; Dehning, Bernd; Sapinski, Mariusz; Bartosik, Marcin R.; Alexopoulos, Andreas; Kurfürst, Christoph; Härkönen, Jaakko

    2016-07-01

    Beam Loss Monitors (BLM) made of silicon are new devices for monitoring of radiation environment in the vicinity of superconductive magnets of the Large Hadron Collider. The challenge of BLMs is extreme radiation hardness, up to 1016 protons/cm2 while placed in superfluid helium (temperature of 1.9 K). CERN BE-BI-BL group, together with CERN-RD39 collaboration, has developed prototypes of BLMs and investigated their device physics. An overview of this development-results of the in situ radiation tests of planar silicon detectors at 1.9 K, performed in 2012 and 2014-is presented. Our main finding is that silicon detectors survive under irradiation to 1×1016 p/cm2 at 1.9 K. In order to improve charge collection, current injection into the detector sensitive region (Current Injection Detector (CID)) was tested. The results indicate that the detector signal increases while operated in CID mode.

  1. [Post-marketing clinical safety assessment of Shenmai injection based on active monitoring and passive monitoring in large data background].

    PubMed

    Wang, Lian-xin; Xie, Yan-ming; Ai, Qing-hua; Song, Nian-bin

    2015-12-01

    This paper adopted a series of related analysis methods to comprehensively analyze post-marketing clinical safety data of Shenmai injection from 4,220 cases of SRS and 32,358 cases of multicenter, prospective, registered hospital centralized monitoring in large data background, calculated ADR incidence rate was 0.93 per 1,000, main symptoms of ADR includes chest pain, chills, skin itching, palpitations, fever, nausea, dizziness, vomiting, flushing, numbness, allergic reaction, cyanosis, rash, low back pain, and "breath", "anaphylactoid reaction" and "flush" were the safety warning signals of Shenmai injection. Primary disease for chronic pulmonary heart disease, thyroid disease, and combined with cerebral vascular disease, prior to the injection and continuous use of alprostadil, cyclic adenosine monophosphate, combined with quinolones, penicillins were suspicious influence factors of ADR of Shenmai injection, these promot the clinical safety. PMID:27245017

  2. The large-scale ionospheric electric field - Its variation with magnetic activity and relation to terrestrial kilometric radiation

    NASA Technical Reports Server (NTRS)

    Holzworth, R. H.; Cullers, D. K.; Hudson, M. K.; Berthelier, J.-J.; Fahleson, U. V.; Falthammar, C.-G.; Jalonen, L.; Tanskanen, P.; Kelley, M. C.; Kellogg, P. J.

    1977-01-01

    Four days of simultaneous auroral zone electric field measurements on balloons flown from six sites spanning 180 deg of magnetic longitude have been analyzed. The average electric field behavior during this magnetically quiet epoch is consistent with earlier single-point measurements, although the average auroral zone electric field was more affected by corotation effects than it was during more disturbed times. When these data, which primarily reflect the large-scale (several hundred kilometer) ionospheric electric field, are mapped to the equator, a steady dawn to dusk component is apparent only on the average, while instantaneously the field is quite variable. The ionospheric electric field during isolated substorms is shown to have differing signatures east and west of 2200 LT. A worldwide positive correlation is shown to exist between the auroral zone electric field strength and the intensity of terrestrial kilometric radiation.

  3. Short-Range Temporal Interactions in Sleep; Hippocampal Spike Avalanches Support a Large Milieu of Sequential Activity Including Replay.

    PubMed

    Mahoney, J Matthew; Titiz, Ali S; Hernan, Amanda E; Scott, Rod C

    2016-01-01

    Hippocampal neural systems consolidate multiple complex behaviors into memory. However, the temporal structure of neural firing supporting complex memory consolidation is unknown. Replay of hippocampal place cells during sleep supports the view that a simple repetitive behavior modifies sleep firing dynamics, but does not explain how multiple episodes could be integrated into associative networks for recollection during future cognition. Here we decode sequential firing structure within spike avalanches of all pyramidal cells recorded in sleeping rats after running in a circular track. We find that short sequences that combine into multiple long sequences capture the majority of the sequential structure during sleep, including replay of hippocampal place cells. The ensemble, however, is not optimized for maximally producing the behavior-enriched episode. Thus behavioral programming of sequential correlations occurs at the level of short-range interactions, not whole behavioral sequences and these short sequences are assembled into a large and complex milieu that could support complex memory consolidation.

  4. Short-Range Temporal Interactions in Sleep; Hippocampal Spike Avalanches Support a Large Milieu of Sequential Activity Including Replay.

    PubMed

    Mahoney, J Matthew; Titiz, Ali S; Hernan, Amanda E; Scott, Rod C

    2016-01-01

    Hippocampal neural systems consolidate multiple complex behaviors into memory. However, the temporal structure of neural firing supporting complex memory consolidation is unknown. Replay of hippocampal place cells during sleep supports the view that a simple repetitive behavior modifies sleep firing dynamics, but does not explain how multiple episodes could be integrated into associative networks for recollection during future cognition. Here we decode sequential firing structure within spike avalanches of all pyramidal cells recorded in sleeping rats after running in a circular track. We find that short sequences that combine into multiple long sequences capture the majority of the sequential structure during sleep, including replay of hippocampal place cells. The ensemble, however, is not optimized for maximally producing the behavior-enriched episode. Thus behavioral programming of sequential correlations occurs at the level of short-range interactions, not whole behavioral sequences and these short sequences are assembled into a large and complex milieu that could support complex memory consolidation. PMID:26866597

  5. Short-Range Temporal Interactions in Sleep; Hippocampal Spike Avalanches Support a Large Milieu of Sequential Activity Including Replay

    PubMed Central

    Mahoney, J. Matthew; Titiz, Ali S.; Hernan, Amanda E.; Scott, Rod C.

    2016-01-01

    Hippocampal neural systems consolidate multiple complex behaviors into memory. However, the temporal structure of neural firing supporting complex memory consolidation is unknown. Replay of hippocampal place cells during sleep supports the view that a simple repetitive behavior modifies sleep firing dynamics, but does not explain how multiple episodes could be integrated into associative networks for recollection during future cognition. Here we decode sequential firing structure within spike avalanches of all pyramidal cells recorded in sleeping rats after running in a circular track. We find that short sequences that combine into multiple long sequences capture the majority of the sequential structure during sleep, including replay of hippocampal place cells. The ensemble, however, is not optimized for maximally producing the behavior-enriched episode. Thus behavioral programming of sequential correlations occurs at the level of short-range interactions, not whole behavioral sequences and these short sequences are assembled into a large and complex milieu that could support complex memory consolidation. PMID:26866597

  6. Metformin Improves Insulin Signaling in Obese Rats via Reduced IKKbeta Action in a Fiber-Type Specific Manner.

    PubMed

    Bikman, Benjamin T; Zheng, Donghai; Kane, Daniel A; Anderson, Ethan J; Woodlief, Tracey L; Price, Jesse W; Dohm, G Lynis; Neufer, P Darrell; Cortright, Ronald N

    2010-01-01

    Metformin is a widely used insulin-sensitizing drug, though its mechanisms are not fully understood. Metformin has been shown to activate AMPK in skeletal muscle; however, its effects on the inhibitor of kappaB kinasebeta (IKKbeta) in this same tissue are unknown. The aim of this study was to (1) determine the ability of metformin to attenuate IKKbeta action, (2) determine whether changes in AMPK activity are associated with changes in IKKbeta action in skeletal muscle, and (3) examine whether changes in AMPK and IKKbeta function are consistent with improved insulin signaling. Lean and obese male Zuckers received either vehicle or metformin by oral gavage daily for four weeks (four groups of eight). Proteins were measured in white gastrocnemius (WG), red gastrocnemius (RG), and soleus. AMPK phosphorylation increased (P < .05) in WG in both lean (57%) and obese (106%), and this was supported by an increase in phospho-ACC in WG. Further, metformin increased IkappaBalpha levels in both WG (150%) and RG (67%) of obese rats, indicative of reduced IKKbeta activity (P < .05), and was associated with reduced IRS1-pSer(307) (30%) in the WG of obese rats (P < .02). From these data we conclude that metformin treatment appears to exert an inhibitory influence on skeletal muscle IKKbeta activity, as evidenced by elevated IkappaBalpha levels and reduced IRS1-Ser(307) phosphorylation in a fiber-type specific manner. PMID:20798864

  7. Prediction of Large Joint Destruction in Patients With Rheumatoid Arthritis Using 18F-FDG PET/CT and Disease Activity Score.

    PubMed

    Suto, Takahito; Okamura, Koichi; Yonemoto, Yukio; Okura, Chisa; Tsushima, Yoshito; Takagishi, Kenji

    2016-02-01

    The assessments of joint damage in patients with rheumatoid arthritis (RA) are mainly restricted to small joints in the hands and feet. However, the development of arthritis in RA patients often involves the large joints, such as the shoulder, elbow, hip, knee, and ankle. Few studies have been reported regarding the degree of large joint destruction in RA patients. F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) visualizes the disease activity in large joints affected by RA. In this study, the associations between destruction of the large joints and the findings of FDG-PET/CT as well as laboratory parameters were investigated, and factors associated with large joint destruction after the administration of biological therapy were identified in RA patients. A total of 264 large joints in 23 RA patients (6 men and 17 women; mean age of 66.9 ± 7.9 years) were assessed in this study. FDG-PET/CT was performed at baseline and 6 months after the initiation of biological therapy. The extent of FDG uptake in large joints (shoulder, elbow, wrist, hip, knee, and ankle) was analyzed using the maximum standardized uptake value (SUVmax). Radiographs of the 12 large joints per patient obtained at baseline and after 2 years were assessed according to Larsen's method. A logistic regression analysis was performed to determine the factors most significantly contributing to the progression of joint destruction within 2 years. Radiographic progression of joint destruction was detected in 33 joints. The SUVmax at baseline and 6 months, and the disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR) at 6, 12, and 24 months were significantly higher in the group with progressive joint destruction. The SUVmax at baseline and DAS28-ESR at 6 months were found to be factors associated with joint destruction at 2 years (P < 0.05). The FDG uptake in the joints with destruction was higher than that observed in the joints

  8. Prediction of Large Joint Destruction in Patients With Rheumatoid Arthritis Using 18F-FDG PET/CT and Disease Activity Score

    PubMed Central

    Suto, Takahito; Okamura, Koichi; Yonemoto, Yukio; Okura, Chisa; Tsushima, Yoshito; Takagishi, Kenji

    2016-01-01

    Abstract The assessments of joint damage in patients with rheumatoid arthritis (RA) are mainly restricted to small joints in the hands and feet. However, the development of arthritis in RA patients often involves the large joints, such as the shoulder, elbow, hip, knee, and ankle. Few studies have been reported regarding the degree of large joint destruction in RA patients. 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) visualizes the disease activity in large joints affected by RA. In this study, the associations between destruction of the large joints and the findings of FDG-PET/CT as well as laboratory parameters were investigated, and factors associated with large joint destruction after the administration of biological therapy were identified in RA patients. A total of 264 large joints in 23 RA patients (6 men and 17 women; mean age of 66.9 ± 7.9 years) were assessed in this study. FDG-PET/CT was performed at baseline and 6 months after the initiation of biological therapy. The extent of FDG uptake in large joints (shoulder, elbow, wrist, hip, knee, and ankle) was analyzed using the maximum standardized uptake value (SUVmax). Radiographs of the 12 large joints per patient obtained at baseline and after 2 years were assessed according to Larsen's method. A logistic regression analysis was performed to determine the factors most significantly contributing to the progression of joint destruction within 2 years. Radiographic progression of joint destruction was detected in 33 joints. The SUVmax at baseline and 6 months, and the disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR) at 6, 12, and 24 months were significantly higher in the group with progressive joint destruction. The SUVmax at baseline and DAS28-ESR at 6 months were found to be factors associated with joint destruction at 2 years (P < 0.05). The FDG uptake in the joints with destruction was higher than that observed in the

  9. The interaction between active normal faulting and large scale gravitational mass movements revealed by paleoseismological techniques: A case study from central Italy

    NASA Astrophysics Data System (ADS)

    Moro, M.; Saroli, M.; Gori, S.; Falcucci, E.; Galadini, F.; Messina, P.

    2012-05-01

    Paleoseismological techniques have been applied to characterize the kinematic behaviour of large-scale gravitational phenomena located in proximity of the seismogenic fault responsible for the Mw 7.0, 1915 Avezzano earthquake and to identify evidence of a possible coseismic reactivation. The above mentioned techniques were applied to the surface expression of the main sliding planes of the Mt. Serrone gravitational deformation, located in the southeastern border of the Fucino basin (central Italy). The approach allows us to detect instantaneous events of deformation along the uphill-facing scarp. These events are testified by the presence of faulted deposits and colluvial wedges. The identified and chronologically-constrained episodes of rapid displacement can be probably correlated with seismic events determined by the activation of the Fucino seismogenic fault, affecting the toe of the gravitationally unstable rock mass. Indeed this fault can produce strong, short-term dynamic stresses able to trigger the release of local gravitational stress accumulated by Mt. Serrone's large-scale gravitational phenomena. The applied methodology could allow us to better understand the geometric and kinematic relationships between active tectonic structures and large-scale gravitational phenomena. It would be more important in seismically active regions, since deep-seated gravitational slope deformations can evolve into a catastrophic collapse and can strongly increase the level of earthquake-induced hazards.

  10. NEMO Binding Domain peptide inhibits constitutive NF-κB activity and reduces tumor burden in a canine model of relapsed, refractory Diffuse Large B-Cell Lymphoma

    PubMed Central

    Gaurnier-Hausser, Anita; Patel, Reema; Baldwin, Albert S.; May, Michael J.; Mason, Nicola J.

    2011-01-01

    Purpose Activated B-Cell Diffuse Large B-Cell Lymphoma (ABC-DLBCL) is an aggressive, poorly chemoresponsive lymphoid malignancy characterized by constitutive canonical NF-κB activity that promotes lymphomagenesis and chemotherapy resistance via over-expression of anti-apoptotic NF-κB target genes. Inhibition of the canonical NF-κB pathway may therefore have therapeutic relevance in ABC-DLBCL. Here we set out to determine whether dogs with spontaneous DLBCL have comparative aberrant constitutive NF-κB activity and to determine the therapeutic relevance of NF-κB inhibition in dogs with relapsed, resistant DLBCL. Experimental Design Canonical NF-κB activity was evaluated by electrophoretic mobility shift assays and immunoblot analyses, and NF-κB target gene expression was measured by qRT-PCR. Primary malignant canine B lymphocytes were treated with the selective IKK complex inhibitor Nemo Binding Domain (NBD) peptide, and evaluated for NF-κB activity and apoptosis. NBD peptide was administered intra-nodally to dogs with relapsed B-cell lymphoma and NF-κB target gene expression and tumor burden were evaluated pre and post treatment. Results Constitutive canonical NF-κB activity and increased NF-κB target gene expression was detected in primary DLBCL tissue. NBD peptide inhibited this activity and induced apoptosis of primary malignant B cells in vitro. Intra-tumoral injections of NBD peptide to dogs with relapsed DLBCL inhibited NF-κB target gene expression and reduced tumor burden. Conclusions This work shows that dogs with spontaneous DLBCL represent a clinically relevant, spontaneous, large animal model for human ABC-DLBCL and demonstrates the therapeutic relevance of NF-κB inhibition in the treatment of ABC-DLBCL. These results have important translational relevance for ABC-DLBCL treatment in human patients. PMID:21610150

  11. P/2008 CL94 (Lemmon) and P/2011 S1 (Gibbs): comet-like activity at large heliocentric distances

    NASA Astrophysics Data System (ADS)

    Kulyk, I.; Korsun, P.; Rousselot, P.; Afanasiev, V.; Ivanova, O.

    2016-06-01

    Based on spectroscopic and photometric observations we analyzed the dust environment of two minor distant objects, P/2008 CL94 (Lemmon) and P/2011 S1 (Gibbs). Both targets demonstrated the comet-like activity beyond the "zone of water-ice sublimation". Meanwhile the spectrum of P/2008 CL94 (Lemmon) did not reveal molecular emission features above reflected continuum in a spectral region of 4100-6800Å. Reddening of the continuum is linear along the dispersion with the mean normalized reflectivity gradient equals to 2.0% ± 0.4%. The normalized reflectivity of P/2011 S1 (Gibbs) derived from the V-R and R-I color indices equals 11% ± 9% and 26% ± 6% respectively. Both objects have likely small nuclei (about 2 and 4 km in the radii for P/2008 CL94 and P/2011 S1 respectively), which are consistent with nucleus sizes of 'Jupiter-family' comets. The level of physical activity of P/2008 CL94 and S/2011 S1 is characterized by R-Afρ quantity of 106 ± 3 cm and 76 ± 8 cm respectively. The Afρ values are resulted in dust production rates of about 1-2 kg/s, assuming the average geometric albedo of grains of 0.1 and the dust outflow velocities between 1 and 10 m/s.

  12. Spatial Gradients in Halogen Oxides Across the North Slope of Alaska Indicate That Halogen Activated Airmasses are Spatially Large

    NASA Astrophysics Data System (ADS)

    Simpson, W. R.; Hoenninger, G. S.; Platt, U.

    2005-12-01

    Reactive halogens are important oxidizers in the polar atmosphere during springtime. They deplete tropospheric ozone, oxidize hydrocarbons, and oxidize gas-phase mercury, causing it to deposit to the snow pack. We want to understand the mechanism by which halides in on snow/ice crystals and/or in aerosol particles are converted to reactive halogen species. This understanding can assist in prediction of mercury deposition and how that deposition depends on environmental variables like sea-ice extent and temperature. This mechanistic knowledge is particularly important in the context of a changing Arctic system. To study halogen activation, we are working in the Studies of the Northern Alaskan Coastal System (SNACS) project and here show results from 2005 including the LEADX experiment. A number of studies have implicated leads (cracks in the sea ice) as a source of halogen activation, but it is unclear if halogens are directly activated on ice surfaces at the lead (e.g. frost flowers) or if the lead is less directly involved. To address the role of leads in halogen activation, we measured bromine monoxide (BrO) using Multiple Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) at Barrow and Atqasuk, Alaska over a four-month period. The locations of these sites, either on the coast near a recurring lead in the case of Barrow, or 100km inland in the case of Atqasuk provides an ability to measure spatial gradients on the 100km length scale. In addition, the Barrow instrument was the first implementation of fully automated two dimensional MAX-DOAS where both elevation and azimuth were scanned. Because the MAX-DOAS method typically detects path-averaged BrO amounts between the instrument and a range of approximately 10km, differences in BrO between viewing azimuths allows us to determine short-length scale BrO gradients. From the 2-D MAX-DOAS observations at Barrow, we find that there are very small if any spatial gradients on the 10km length scale. From the

  13. Hierarchical chlorine-doped rutile TiO{sub 2} spherical clusters of nanorods: Large-scale synthesis and high photocatalytic activity

    SciTech Connect

    Xu Hua; Zheng Zhi; Zhang Lizhi Zhang Hailu; Deng Feng

    2008-09-15

    In this study, we report the synthesis of hierarchical chlorine-doped rutile TiO{sub 2} spherical clusters of nanorods photocatalyst on a large scale via a soft interface approach. This catalyst showed much higher photocatalytic activity than the famous commercial titania (Degussa P25) under visible light ({lambda}>420 nm). The resulting sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy, {sup 1}H solid magic-angle spinning nuclear magnetic resonance (MAS-NMR) and photoluminescence spectroscopy. On the basis of characterization results, we found that the doping of chlorine resulted in red shift of absorption and higher surface acidity as well as crystal defects in the photocatalyst, which were the reasons for high photocatalytic activity of chlorine-doped TiO{sub 2} under visible light ({lambda}>420 nm). These hierarchical chlorine-doped rutile TiO{sub 2} spherical clusters of nanorods are very attractive in the fields of environmental pollutants removal and solar cell because of their easy separation and high activity. - Graphical abstract: Hierarchical chlorine-doped rutile TiO{sub 2} spherical clusters of nanorods photocatalyst were synthesized on a large scale via a soft interface approach. This catalyst showed much higher photocatalytic activity than the famous commercial titania (Degussa P25) under visible light ({lambda}>420 nm)

  14. Fully relativistic complete active space self-consistent field for large molecules: Quasi-second-order minimax optimization

    SciTech Connect

    Bates, Jefferson E.; Shiozaki, Toru

    2015-01-28

    We develop an efficient algorithm for four-component complete active space self-consistent field (CASSCF) methods on the basis of the Dirac equation that takes into account spin–orbit and other relativistic effects self-consistently. Orbitals are optimized using a trust-region quasi-Newton method with Hessian updates so that energies are minimized with respect to rotations among electronic orbitals and maximized with respect to rotations between electronic and positronic orbitals. Utilizing density fitting and parallel computation, we demonstrate that Dirac–Coulomb CASSCF calculations can be routinely performed on systems with 100 atoms and a few heavy-elements. The convergence behavior and wall times for octachloridodirhenate(III) and a tungsten methylidene complex are presented. In addition, the excitation energies of octachloridodirhenate(III) are reported using a state-averaged variant.

  15. Habitat Composition and Connectivity Predicts Bat Presence and Activity at Foraging Sites in a Large UK Conurbation

    PubMed Central

    Hale, James D.; Fairbrass, Alison J.; Matthews, Tom J.; Sadler, Jon P.

    2012-01-01

    Background Urbanization is characterized by high levels of sealed land-cover, and small, geometrically complex, fragmented land-use patches. The extent and density of urbanized land-use is increasing, with implications for habitat quality, connectivity and city ecology. Little is known about densification thresholds for urban ecosystem function, and the response of mammals, nocturnal and cryptic taxa are poorly studied in this respect. Bats (Chiroptera) are sensitive to changing urban form at a species, guild and community level, so are ideal model organisms for analyses of this nature. Methodology/Principal Findings We surveyed bats around urban ponds in the West Midlands conurbation, United Kingdom (UK). Sites were stratified between five urban land classes, representing a gradient of built land-cover at the 1 km2 scale. Models for bat presence and activity were developed using land-cover and land-use data from multiple radii around each pond. Structural connectivity of tree networks was used as an indicator of the functional connectivity between habitats. All species were sensitive to measures of urban density. Some were also sensitive to landscape composition and structural connectivity at different spatial scales. These results represent new findings for an urban area. The activity of Pipistrellus pipistrellus (Schreber 1774) exhibited a non-linear relationship with the area of built land-cover, being much reduced beyond the threshold of ∼60% built surface. The presence of tree networks appears to mitigate the negative effects of urbanization for this species. Conclusions/Significance Our results suggest that increasing urban density negatively impacts the study species. This has implications for infill development policy, built density targets and the compact city debate. Bats were also sensitive to the composition and structure of the urban form at a range of spatial scales, with implications for land-use planning and management. Protecting and

  16. Synthesis of large surface area nano-sized BiVO{sub 4} by an EDTA-modified hydrothermal process and its enhanced visible photocatalytic activity

    SciTech Connect

    Sun Wanting; Xie Mingzheng; Jing Liqiang; Luan Yunbo; Fu Honggang

    2011-11-15

    In this work, monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been successfully synthesized, using Bi(NO{sub 3}){sub 3} and NH{sub 4}VO{sub 3} as raw materials, through a hydrothermal process in the presence of ethylene diamine tetraacetic acid (EDTA). It is demonstrated that the nanoparticle size of as-prepared BiVO{sub 4} becomes small by decreasing hydrothermal temperature, shortening hydrothermal reaction time and increasing EDTA amount used. The resulting BiVO{sub 4} nanoparticle with large surface area exhibits a good photocatalytic performance for degrading phenol solution as a model organic pollutant under visible illumination. The key of this method is the chelating role of EDTA group in the synthetic process that it can greatly control the concentration of Bi{sup 3+}, leading to the growth inhibition of BiVO{sub 4} crystallite. The work provides a route for the synthesis of Bi-containing nano-sized composite oxides with large surface area. - Graphical abstract: High visible active nano-sized BiVO{sub 4} photocatalyst with large surface area is successfully synthesized, which is attributed to the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. Highlights: > Monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been synthesized by a hydrothermal process. > Key of this method is the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. > Resulting nano-sized BiVO{sub 4} exhibits a good photocatalytic activity for degrading phenol under visible illumination.

  17. Ferrocene/fullerene hybrids showing large second-order nonlinear optical activities: impact of the cage unit size.

    PubMed

    Wang, Wen-Yong; Wang, Li; Ma, Na-Na; Zhu, Chang-Li; Qiu, Yong-Qing

    2015-06-01

    The electron donor-acceptor complexes, which undergo intramolecular charge transfer under external stimulus, are an emerging class of materials showing important application in nonlinear optics. Synthesizing ferrocene/fullerene complexes through face-to-face fusion would enjoy the merits of both ferrocene and fullerene due to their strong donor-acceptor interactions. Four ferrocene/fullerene hybrid complexes with the gradual extension of fullerene cage size, including CpFe(C60H5), CpFe(C66H5), CpFe(C70H5), and CpFe(C80H5) (Cp is cyclopentadienyl), have been investigated by density functional theory. These hybrid molecules give eclipsed and staggered isomers. The main reason that the eclipsed isomer is stable is that the eclipsed structure possesses large CpFefullerene bonding energy. The CpFefullerene interaction is smaller than that of CpFefullerene, which must come from two different interfaces. The presence of covalent bond character between CpFe and fullerene is supported by the localized orbital locator, deformation of electron density distribution and energy decomposition analysis. Significantly, the absorption bands and first hyperpolarizabilities of these hybrid complexes are strongly sensitive to the fullerene cage size, which is ascribed to a change in the charge transfer pattern, especially for CpFe(C80H5), which displays reverse π → π* charge transfer from bottom to top cage, leading to notable hyperpolarizability. Investigation of the structure-property relationship at the molecular level can benefit the design and preparation of such hybrid complexes in chemistry and materials science.

  18. The somatic hypermutation activity of a follicular lymphoma links to large insertions and deletions of immunoglobulin genes.

    PubMed

    Wu, H Y; Kaartinen, M

    1995-07-01

    A biopsy specimen from a patient with follicular lymphoma was divided into two fragments. DNA was extracted from one fragment and a 1.2 kb region of the functional heavy chain (IgH) gene was amplified, cloned and sequenced (eight clones). From the other fragment a cell line (HF-1) was started. The IgH gene region was amplified from the cell line, and sequenced without cloning. The nine sequences obtained could be arranged into a genealogical tree where the individual sequences differed from the deduced ancestor by 16-29 single nucleotide changes, some also by an insertion and/or a deletion. It is apparent that the sequence alterations were caused by somatic mutations during the growth of the lymphoma. The comparison of the sequences with two published (allelic) germline sequences of the human JH region showed approximately 20% non-homology. The differences included five additional multinucleotide insertion/deletion changes, the longest of them a 101-nucleotide insertion. Two long insertions were homologous to the adjacent germline sequences. We propose that most of the changes observed, including long deletions and insertions, represent or are linked to somatic hypermutation events of the Ig gene type. Although in a few cases large deletions and insertions (> 2 bp) have been found in mutated immunoglobulin genes, our results, for the first time, firmly link these deletions/insertions to somatic hypermutations; their frequency was found to be 2.2% of the observed mutational events in the non-translated gene regions. HF-1 is the first follicular lymphoma line successfully established from a lymphoma known to have hypermutated its Ig genes during the malignant growth. It is a candidate cell line to be studied for its ability to generate mutations of B cell type in cell cultures.

  19. The power stability of a fiber amplifier based on a multifunction card and PID control program

    NASA Astrophysics Data System (ADS)

    Zhang, Linjie; Yang, Wenguang; Zhang, Hao; Zhao, JianMing; Jia, Suotang

    2016-06-01

    The power stability of a fiber amplifier was significantly improved by means of simultaneously controlling the current of a fiber amplifier and the diffraction efficiency of an acousto-optical modulator. The real-time fluctuation of laser power was recorded by a multifunction card and processed by a proportional-integral-derivative (PID) control program. The feedback loop voltage was introduced to the fiber laser amplifier and acoustic-optic modulator through the analog output of the multifunction card. The control method based on a multifunction card and PID program has good scalability, flexibility and reliability for the complex system on the condition in which the frequency and power of the laser need to be precisely stabilized.

  20. Real time monitoring of a fiber fuse using an optical time-domain reflectometer.

    PubMed

    Abedin, Kazi S; Nakazawa, Masataka

    2010-09-27

    We propose and experimentally demonstrate monitoring of a fiber fuse in real time using an optical time domain reflectometer (OTDR). When a fuse starts, a weak reflection of light occurs from the leading edge of the fuse where plasma and voids are being formed in the core. In this work, we examined the possibility of monitoring a fiber fuse from a remote location using an OTDR. We demonstrate a method that allows us detect a fuse progressing at remote locations (over kilometers away). It was found to be effective even in the presence of strong spurious backscattering, such as spontaneous Raman scattering due to a strong continuous wave pump. Moreover, from the progress of the reflection edge monitored by the OTDR, the fuse velocity could be readily determined.

  1. The power stability of a fiber amplifier based on a multifunction card and PID control program

    NASA Astrophysics Data System (ADS)

    Zhang, Linjie; Yang, Wenguang; Zhang, Hao; Zhao, JianMing; Jia, Suotang

    2016-06-01

    The power stability of a fiber amplifier was significantly improved by means of simultaneously controlling the current of a fiber amplifier and the diffraction efficiency of an acousto-optical modulator. The real-time fluctuation of laser power was recorded by a multifunction card and processed by a proportional–integral–derivative (PID) control program. The feedback loop voltage was introduced to the fiber laser amplifier and acoustic-optic modulator through the analog output of the multifunction card. The control method based on a multifunction card and PID program has good scalability, flexibility and reliability for the complex system on the condition in which the frequency and power of the laser need to be precisely stabilized.

  2. Blockade of oncogenic IκB kinase activity in diffuse large B-cell lymphoma by bromodomain and extraterminal domain protein inhibitors.

    PubMed

    Ceribelli, Michele; Kelly, Priscilla N; Shaffer, Arthur L; Wright, George W; Xiao, Wenming; Yang, Yibin; Mathews Griner, Lesley A; Guha, Rajarshi; Shinn, Paul; Keller, Jonathan M; Liu, Dongbo; Patel, Paresma R; Ferrer, Marc; Joshi, Shivangi; Nerle, Sujata; Sandy, Peter; Normant, Emmanuel; Thomas, Craig J; Staudt, Louis M

    2014-08-01

    In the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), NF-κB activity is essential for viability of the malignant cells and is sustained by constitutive activity of IκB kinase (IKK) in the cytoplasm. Here, we report an unexpected role for the bromodomain and extraterminal domain (BET) proteins BRD2 and BRD4 in maintaining oncogenic IKK activity in ABC DLBCL. IKK activity was reduced by small molecules targeting BET proteins as well as by genetic knockdown of BRD2 and BRD4 expression, thereby inhibiting downstream NF-κB-driven transcriptional programs and killing ABC DLBCL cells. Using a high-throughput platform to screen for drug-drug synergy, we observed that the BET inhibitor JQ1 combined favorably with multiple drugs targeting B-cell receptor signaling, one pathway that activates IKK in ABC DLBCL. The BTK kinase inhibitor ibrutinib, which is in clinical development for the treatment of ABC DLBCL, synergized strongly with BET inhibitors in killing ABC DLBCL cells in vitro and in a xenograft mouse model. These findings provide a mechanistic basis for the clinical development of BET protein inhibitors in ABC DLBCL, particularly in combination with other modulators of oncogenic IKK signaling.

  3. Major temporal variations in shortening rate absorbed along a large active fold of the southeastern Tianshan piedmont (China)

    NASA Astrophysics Data System (ADS)

    Saint-Carlier, Dimitri; Charreau, Julien; Lavé, Jérôme; Blard, Pierre-Henri; Dominguez, Stéphane; Avouac, Jean-Philippe; Wang, Shengli

    2016-01-01

    The investigation of deformation rates on a mountain piedmont can provide key information for improving our understanding of the overall dynamics of a mountain range. Here, we estimate the shortening rate absorbed by a Quaternary emergent detachment fold on the southeastern piedmont of the Tianshan (China). Our work is primarily based on new 10Be cosmogenic exposure dating of deformed alluvial surfaces. The method we have developed combines depth profiling with sampling of surface cobbles, thereby allowing exposure time, erosion rate and inheritance to be simultaneously constrained. The exposure ages of the uppermost uplifted alluvial surfaces are around 140 ± 17 ka, 130 ± 9 ka and 47 ± 9 ka, from west to east. A terrace lying below the 140 ka surface is dated at 65 ± 5 ka. The ages of the uplifted and folded alluvial surfaces were then combined with estimates of shortening obtained using two distinct methods: (1) the excess area method, where sedimentation rates, extracted from magnetostratigraphic studies, are used to determine the amount of sedimentation after the abandonment of the river; and (2) a folding model derived from sandbox experiments. The late Pleistocene shortening rates are shown to be between 0.4 ± 0.1 mm /yr and 0.8 ± 0.5 mm /yr on the western part of the fold and 2.1 ± 0.4 mm /yr along its central part. The central part of the frontal Yakeng anticline therefore accommodates up to 25% of the total shortening currently absorbed across the whole Eastern Tianshan range (8 mm/yr). However, this situation seems to have prevailed for only the last 150 ka, as the shortening rate absorbed by this nascent fold was previously ten times slower. While the initiation of folding of the Yakeng anticline can be traced back to 5.5 Ma ago, the basinward migration of the active deformation front onto the Yakeng fold is a relatively recent phenomenon and appears to be diachronous from west to east, probably in relation to the tectonic activity of the folds in

  4. Active Tectonics In The Rukwa Rift (sw Tanzania): A Study of The Potential For Large Earthquakes In A Continental Rift.

    NASA Astrophysics Data System (ADS)

    Kervyn, F.

    The Rukwa rift is a deep sedimentary basin that is considered as a tectonic trans- fer zone between the Tanganyika and the Malawi troughs. The tectonic evolution of the depression is controlled by the reactivation of proterozoic structures and started with the deposition of the permo-triasic Karoo sediments. In the southeast, the rift is divided into two facing half graben separated by a Precambrian horst, whereas its northwestern part has a more symmetrical graben structure. Although most of the vertical displacement is accommodated by the Lupa eastern boundary fault, onshore shallow seismic profiles have confirmed the co-occurrence of intrabasin synthetic- and strike-slip faults within the sub surface sediments. Both normal and dextral strike-slip movement are indeed observed in the basin in response to the E-W to WNW-SSE ex- tension. The region has a moderate seismic activity and the earthquakes magnitude is generally below M 6.5. However, a M 7.4 earthquake occurred in the Rukwa region in 1910 but its exact location remains uncertain. The current research aimed at the identi- fication of active faults within the recent deposits of the basin by the combination in a GIS of radar interferometric data with topographical and geological maps, geophysical data, and field observations. Radar interferometry (InSAR) was found to be especially suitable for DEM computation in low relief areas where available topographic data are limited in accuracy. Numerous topographic lineaments were observed on InSAR DEM, and follow two main directions, both oblique to the main NW-SE trend of the rift. On the one hand, the GIS analysis confirms that the observed lineaments corre- spond to real natural alignment such like the drainage for example, and are therefore not related to atmospheric artefacts. On the other hand, the field observations revealed that in most cases, the topographic lineaments are very subtle and difficult to identify. However, direct correlations with tectonic

  5. Highly efficient graphene-based Cu(In, Ga)Se₂ solar cells with large active area.

    PubMed

    Yin, Ling; Zhang, Kang; Luo, Hailin; Cheng, Guanming; Ma, Xuhang; Xiong, Zhiyu; Xiao, Xudong

    2014-09-21

    Two-dimensional graphene has tremendous potential to be used as a transparent conducting electrode (TCE), owing to its high transparency and conductivity. To date graphene films have been applied to several kinds of solar cells except the Cu(In, Ga)Se₂ (CIGS) solar cell. In this work, we present a novel TCE structure consisting of a doped graphene film and a thin layer of poly(methyl methacrylate) (PMMA) to replace the ZnO:Al (AZO) electrode for CIGS. By optimizing the contact between graphene and intrinsic ZnO (i-ZnO), a high power conversion efficiency (PCE) of 13.5% has been achieved, which is among the highest efficiencies of graphene-based solar cells ever reported and approaching those of AZO-based solar cells. Besides, the active area of our solar cells reaches 45 mm(2), much larger than other highly efficient graphene-based solar cells (>10%) reported so far. Moreover, compared with AZO-based CIGS solar cells, the total reflectance of the graphene-based CIGS solar cells is decreased and the quantum efficiency of the graphene-based CIGS is enhanced in the near infrared region (NIR), which strongly support graphene as a competitive candidate material for the TCE in the CIGS solar cell. Furthermore, the graphene/PMMA film can protect the solar cell from moisture, making the graphene-based solar cells much more stable than the AZO-based solar cells.

  6. Observing Dynamics in Large-Scale Birkeland Currents with the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE)

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Korth, H.; Waters, C. L.; Barnes, R. J.; Olson, C.

    2015-12-01

    The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) provides continuous global observations of the magnetic perturbations that predominantly reflect Birkeland currents. The data are acquired by avionics magnetometers of the Iridium satellites and allow measurements from 66 satellites in near-polar circular, low altitude orbits. The configuration of the Iridium satellite constellation determines the longitude sampling spacing of ~ 2 hours and the re-sampling cadence of the system which is 9 minutes. From 2008 to 2013 the AMPERE system was developed which included new flight software on the Iridium satellites to allow telemetry of higher rate data to the ground and the Science Data Center to derive Birkeland current perturbations from the data and invert these signals to derive the global distributions of the currents using data windows of ten minutes. There were many challenges in developing AMPERE including automating inter-calibration between satellites and the baseline determination and removals. The results of AMPERE provide stunning confirmation of many of the statistical estimates for the distribution of currents but more significantly open a new window to understand their instantaneous distribution and dynamics. Examples of new features of the currents and their dynamics revealed by AMPERE are presented. In addition, prospects for new data products and increased data quality anticipated from AMPERE-NEXT to be implemented on the Iridium-NEXT generation of satellites are discussed.

  7. On the variation of the ionospheric potential due to large-scale radioactivity enhancement and solar activity

    NASA Astrophysics Data System (ADS)

    Slyunyaev, Nikolay N.; Mareev, Evgeny A.; Zhidkov, Artem A.

    2015-08-01

    Sensitivity of the global electric circuit (GEC) to variations of atmospheric conductivity and current sources is analyzed and discussed. When the undisturbed exponential conductivity profile is assumed all over the Earth, the most substantial changes in the ionospheric potential (IP) are caused by conductivity perturbations inside thunderstorms; if, in addition, conductivity reduction inside thunderstorms and nonelectrified clouds is assumed, the IP becomes less sensitive to conductivity perturbations; besides, the IP is even more sensitive to source current variations than to conductivity. Current source and voltage source descriptions of GEC generators are compared; it is shown that the IP variation may critically depend on the chosen description. As an application, the IP variation due to nuclear weapons testing is studied; it is shown that neither local nor global increase of conductivity in the stratosphere could alone explain the observed 40% IP increase in the 1960s; at the same time this increase might be accounted for by a 40% increase in the source current density or a 46% reduction of the conductivity inside thunderstorms, provided that it was not reduced initially. The IP variation due to solar activity and, in particular, due to solar modulation of galactic cosmic ray flux is also discussed and modeled, which required an adequate parameterization of the rate of atmospheric ion pair production over the solar cycle. It is estimated that the maximum IP variation on the scale of the solar cycle does not exceed 5% of the mean value, unless source current perturbations are taken into account.

  8. Toward endoscopes with no distal optics: video-rate scanning microscopy through a fiber bundle.

    PubMed

    Andresen, Esben Ravn; Bouwmans, Géraud; Monneret, Serge; Rigneault, Hervé

    2013-03-01

    We report a step toward scanning endomicroscopy without distal optics. The focusing of the beam at the distal end of a fiber bundle is achieved by imposing a parabolic phase profile across the exit face with the aid of a spatial light modulator. We achieve video-rate images by galvanometric scanning of the phase tilt at the proximal end. The approach is made possible by the bundle, designed to have very low coupling between cores.

  9. A Fiber Optic Sensor Sensitive To Normal Pressure And Shear Stress

    NASA Astrophysics Data System (ADS)

    Cuomo, Frank W.; Kidwell, Robert S.; Hu, Andong

    1986-11-01

    A fiber optic lever sensing technique that can be used to measure normal pressure as well as shear stresses is discussed. This method uses three unequal fibers combining small size and good sensitivity. Static measurements appear to confirm the theoretical models predicted by geometrical optics and dynamic tests performed at frequencies up to 10 kHz indicate a flat response within this frequency range. These sensors are intended for use in a low speed wind tunnel environment.

  10. Plane Waves of a Fiber-Reinforcement Magneto-thermoelastic Comparison of Three Different Theories

    NASA Astrophysics Data System (ADS)

    Othman, Mohamed I. A.; Said, Samia M.

    2013-02-01

    In this article, the coupled theory, Lord-Shulman theory, and Green-Lindsay (GL) theory are used to study the influence of a magnetic field on a fiber-reinforced thermoelastic half-space. Normal mode analysis is used to solve a thermal shock problem. Numerical results for the temperature, displacement components, and stress components are given and illustrated graphically. A comparison is made between the coupled and GL theories in the absence and presence of a magnetic field and reinforcement.

  11. Design of a fiber-optic transmitter for microwave analog transmission with high phase stability

    NASA Technical Reports Server (NTRS)

    Logan, R. T., Jr.; Lutes, G. F.; Primas, L. E.; Maleki, L.

    1990-01-01

    The principal considerations in the design of fiber-optic transmitters for highly phase-stable radio frequency and microwave analog transmission are discussed. Criteria for a fiber-optic transmitter design with improved amplitude and phase-noise performance are developed through consideration of factors affecting the phase noise, including low-frequency laser-bias supply noise, the magnitude and proximity of external reflections into the laser, and temperature excursions of the laser-transmitter package.

  12. Interrogation system for a fiber-Bragg-grating strain sensor for automotive applications

    NASA Astrophysics Data System (ADS)

    Falciai, Riccardo; Vannini, Andrea

    2001-09-01

    In this paper a derivative spectrometer, utilizing an FFP tunable filter for the wavelength shift detection and an electronic device for the signal processing, was realized and tested for data acquisition and elaboration from a fiber-Bragg-grating strain sensor system for automotive applications. The result of measurements carried out both under static and dynamic conditions have been compared with those performed with a strain gauge.

  13. 3D phase stepping optical profilometry using a fiber optic Lloyd's mirror

    NASA Astrophysics Data System (ADS)

    Kosoglu, Gulsen; Yuksel, Heba; Inci, M. Naci

    2016-04-01

    This study defines measurements of three-dimensional rigid-body shapes by using a fiber optic Lloyd's mirror. A fiber optic Lloyd's mirror assembly is basically a technique to create an optical interference pattern using the real light point sources and their images. The generated fringe pattern thanks to this technique is deformed when it is projected on an object's surface. The introduced surface profilometry algorithm depends on a multi-step phase shifting process. The deformed fringe patterns containing information of the object's surface profile are captured by a digital CCD camera. While each frames are captured, required π/2 phase shifts for interference fringe pattern are obtained by mechanically sliding the Lloyd assembly via an ordinary micrometer stage. Some preprocess algorithms are applied to the frames and are processed with an algorithm to accomplish 3D topographies. Finally, the continuous data determines the depth information and the surface topography of the object. The experimental setup is simple and low cost to construct, and is insensitive to the ambient temperature fluctuations and environmental vibrations that cause unwanted effects on the projected fringe pattern. Such a fiber optic Lloyd's system which provides an accurate non-contact measurement without contaminating and harming the object surface has a wide range of applications from laser interference based lithography in nano-scale to macro-scale interferometers.

  14. Repeated large-magnitude earthquakes in a tectonically active, low-strain continental interior: The northern Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Landgraf, A.; Dzhumabaeva, A.; Abdrakhmatov, K. E.; Strecker, M. R.; Macaulay, E. A.; Arrowsmith, Jr.; Sudhaus, H.; Preusser, F.; Rugel, G.; Merchel, S.

    2016-05-01

    The northern Tien Shan of Kyrgyzstan and Kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries. To assess the significance of such a pulse of strain release in a continental interior, it is important to analyze and quantify strain release over multiple time scales. We have undertaken paleoseismological investigations at two geomorphically distinct sites (Panfilovkoe and Rot Front) near the Kyrgyz capital Bishkek. Although located near the historic epicenters, both sites were not affected by these earthquakes. Trenching was accompanied by dating stratigraphy and offset surfaces using luminescence, radiocarbon, and 10Be terrestrial cosmogenic nuclide methods. At Rot Front, trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years. The scarp rather resembles an extensive debris-flow lobe. At Panfilovkoe, we estimate a Late Pleistocene minimum slip rate of 0.2 ± 0.1 mm/a, averaged over at least two, probably three earthquake cycles. Dip-slip reverse motion along segmented, moderately steep faults resulted in hanging wall collapse scarps during different events. The most recent earthquake occurred around 3.6 ± 1.3 kyr ago (1σ), with dip-slip offsets between 1.2 and 1.4 m. We calculate a probabilistic paleomagnitude to be between 6.7 and 7.2, which is in agreement with regional data from the Kyrgyz range. The morphotectonic signals in the northern Tien Shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer-term coevolution of topography and seismogenic processes in similar structural settings worldwide.

  15. Large-conductance voltage- and Ca2+-activated K+ channel regulation by protein kinase C in guinea pig urinary bladder smooth muscle.

    PubMed

    Hristov, Kiril L; Smith, Amy C; Parajuli, Shankar P; Malysz, John; Petkov, Georgi V

    2014-03-01

    Large-conductance voltage- and Ca(2+)-activated K(+) (BK) channels are critical regulators of detrusor smooth muscle (DSM) excitability and contractility. PKC modulates the contraction of DSM and BK channel activity in non-DSM cells; however, the cellular mechanism regulating the PKC-BK channel interaction in DSM remains unknown. We provide a novel mechanistic insight into BK channel regulation by PKC in DSM. We used patch-clamp electrophysiology, live-cell Ca(2+) imaging, and functional studies of DSM contractility to elucidate BK channel regulation by PKC at cellular and tissue levels. Voltage-clamp experiments showed that pharmacological activation of PKC with PMA inhibited the spontaneous transient BK currents in native freshly isolated guinea pig DSM cells. Current-clamp recordings revealed that PMA significantly depolarized DSM membrane potential and inhibited the spontaneous transient hyperpolarizations in DSM cells. The PMA inhibitory effects on DSM membrane potential were completely abolished by the selective BK channel inhibitor paxilline. Activation of PKC with PMA did not affect the amplitude of the voltage-step-induced whole cell steady-state BK current or the single BK channel open probability (recorded in cell-attached mode) upon inhibition of all major Ca(2+) sources for BK channel activation with thapsigargin, ryanodine, and nifedipine. PKC activation with PMA elevated intracellular Ca(2+) levels in DSM cells and increased spontaneous phasic and nerve-evoked contractions of DSM isolated strips. Our results support the concept that PKC activation leads to a reduction of BK channel activity in DSM via a Ca(2+)-dependent mechanism, thus increasing DSM contractility.

  16. A large Rab GTPase encoded by CRACR2A is a component of subsynaptic vesicles that transmit T cell activation signals.

    PubMed

    Srikanth, Sonal; Kim, Kyun-Do; Gao, Yuanyuan; Woo, Jin Seok; Ghosh, Shubhamoy; Calmettes, Guillaume; Paz, Aviv; Abramson, Jeff; Jiang, Meisheng; Gwack, Yousang

    2016-03-22

    More than 60 members of the Rab family of guanosine triphosphatases (GTPases) exist in the human genome. Rab GTPases are small proteins that are primarily involved in the formation, trafficking, and fusion of vesicles. We showed thatCRACR2A(Ca(2+) release-activated Ca(2+) channel regulator 2A) encodes a lymphocyte-specific large Rab GTPase that contains multiple functional domains, including EF-hand motifs, a proline-rich domain (PRD), and a Rab GTPase domain with an unconventional prenylation site. Through experiments involving gene silencing in cells and knockout mice, we demonstrated a role for CRACR2A in the activation of the Ca(2+) and c-Jun N-terminal kinase signaling pathways in response to T cell receptor (TCR) stimulation. Vesicles containing this Rab GTPase translocated from near the Golgi to the immunological synapse formed between a T cell and a cognate antigen-presenting cell to activate these signaling pathways. The interaction between the PRD of CRACR2A and the guanidine nucleotide exchange factor Vav1 was required for the accumulation of these vesicles at the immunological synapse. Furthermore, we demonstrated that GTP binding and prenylation of CRACR2A were associated with its localization near the Golgi and its stability. Our findings reveal a previously uncharacterized function of a large Rab GTPase and vesicles near the Golgi in TCR signaling. Other GTPases with similar domain architectures may have similar functions in T cells. PMID:27016526

  17. Current-Sensing and Voltage-Feedback Driving Method for Large-Area High-Resolution Active Matrix Organic Light Emitting Diodes

    NASA Astrophysics Data System (ADS)

    In, Hai‑Jung; Choi, Byong‑Deok; Chung, Ho‑Kyoon; Kwon, Oh‑Kyong

    2006-05-01

    There is the problem of picture quality nonuniformity due to thin film transistor (TFT) characteristic variations throughout a panel of large-area high-resolution active matrix organic light emitting diodes. The current programming method could solve this issue, but it also requires very long charging time of a data line at low gray shades. Therefore, we propose a new driving method and a pixel circuit with emission-current sensing and feedback operation in order to resolve these problems. The proposed driving method and pixel circuit successfully compensate threshold voltage and mobility variations of TFTs and overcome the data line charging problem. Simulation results show that emission current deviations of the proposed driving method are less than 1.7% with ± 10.0% mobility and ± 0.3 V threshold voltage variations of pixel-driving TFTs, which means the proposed driving method is applicable to large-area high-resolution applications.

  18. Perspective of detecting very high energy gamma-ray emission from active galactic nuclei with Large High Altitude Air Shower Observatory (LHAASO)

    NASA Astrophysics Data System (ADS)

    Zhao, Yi; Yuan, Qiang; Bi, Xiao-Jun; Zhu, Feng-Rong; Jia, Huan-Yu

    2016-10-01

    The detectability of active galactic nuclei (AGN), a major class of γ-ray emitters in the sky, by the newly planned Chinese project, Large High Altitude Air Shower Observatory (LHAASO), is investigated. The expectation is primarily based on the AGN catalog of Fermi Large Area Telescope (Fermi-LAT), with an extrapolation to the very high energy (VHE) range taking into account the absorption effect by the extragalactic background light (EBL). It is found that LHAASO may have the potential to detect more than several tens of the Fermi detected AGN, basically BL Lacertaes, with one-year sky survey. The capability of measuring the energy spectrum and light curve are also discussed.

  19. Facile synthesis of large-scale Ag nanosheet-assembled films with sub-10 nm gaps as highly active and homogeneous SERS substrates

    NASA Astrophysics Data System (ADS)

    Li, Zhongbo; Meng, Guowen; Liang, Ting; Zhang, Zhuo; Zhu, Xiaoguang

    2013-01-01

    We report a facile low-cost synthetic approach to large-scale Ag nanosheet-assembled films with a high density of uniformly distributed sub-10 nm gaps between the adjacent nanosheets on Si substrates via galvanic cell reactions. The distribution density of Ag nanosheets on substrates could be tailored by tuning the duration of the HF-etching and the concentration of citric acid in the solution. Furthermore, in conjunction with a conventional photolithography, highly uniform patterned Ag nanosheet-assembled structures with different morphologies can be achieved on Si substrates via galvanic-cell-induced growth. By using rhodamine 6G as a standard test molecule, the large-scale Ag nanosheet-assembled films exhibit highly active and homogenous surface-enhanced Raman scattering (SERS) effect and also show promising potentials as reliable SERS substrates for rapid detection of trace polychlorinated biphenyls (PCBs).

  20. Improvement of spatial learning by facilitating large-conductance calcium-activated potassium channel with transcranial magnetic stimulation in Alzheimer's disease model mice.

    PubMed

    Wang, Furong; Zhang, Yu; Wang, Li; Sun, Peng; Luo, Xianwen; Ishigaki, Yasuhito; Sugai, Tokio; Yamamoto, Ryo; Kato, Nobuo

    2015-10-01

    Transcranial magnetic stimulation (TMS) is fragmentarily reported to be beneficial to Alzheimer's patients. Its underlying mechanism was investigated. TMS was applied at 1, 10 or 15 Hz daily for 4 weeks to young Alzheimer's disease model mice (3xTg), in which intracellular soluble amyloid-β is notably accumulated. Hippocampal long-term potentiation (LTP) was tested after behavior. TMS ameliorated spatial learning deficits and enhanced LTP in the same frequency-dependent manner. Activity of the large conductance calcium-activated potassium (Big-K; BK) channels was suppressed in 3xTg mice and recovered by TMS frequency-dependently. These suppression and recovery were accompanied by increase and decrease in cortical excitability, respectively. TMS frequency-dependently enhanced the expression of the activity-dependently expressed scaffold protein Homer1a, which turned out to enhance BK channel activity. Isopimaric acid, an activator of the BK channel, magnified LTP. Amyloid-β lowering was detected after TMS in 3xTg mice. In 3xTg mice with Homer1a knocked out, amyloid-β lowering was not detected, though the TMS effects on BK channel and LTP remained. We concluded that TMS facilitates BK channels both Homer1a-dependently and -independently, thereby enhancing hippocampal LTP and decreasing cortical excitability. Reduced excitability contributed to amyloid-β lowering. A cascade of these correlated processes, triggered by TMS, was likely to improve learning in 3xTg mice.

  1. Animal-borne imaging reveals novel insights into the foraging behaviors and Diel activity of a large-bodied apex predator, the American alligator (Alligator mississippiensis).

    PubMed

    Nifong, James C; Nifong, Rachel L; Silliman, Brian R; Lowers, Russell H; Guillette, Louis J; Ferguson, Jake M; Welsh, Matthew; Abernathy, Kyler; Marshall, Greg

    2014-01-01

    Large-bodied, top- and apex predators (e.g., crocodilians, sharks, wolves, killer whales) can exert strong top-down effects within ecological communities through their interactions with prey. Due to inherent difficulties while studying the behavior of these often dangerous predatory species, relatively little is known regarding their feeding behaviors and activity patterns, information that is essential to understanding their role in regulating food web dynamics and ecological processes. Here we use animal-borne imaging systems (Crittercam) to study the foraging behavior and activity patterns of a cryptic, large-bodied predator, the American alligator (Alligator mississippiensis) in two estuaries of coastal Florida, USA. Using retrieved video data we examine the variation in foraging behaviors and activity patterns due to abiotic factors. We found the frequency of prey-attacks (mean = 0.49 prey attacks/hour) as well as the probability of prey-capture success (mean = 0.52 per attack) were significantly affected by time of day. Alligators attempted to capture prey most frequently during the night. Probability of prey-capture success per attack was highest during morning hours and sequentially lower during day, night, and sunset, respectively. Position in the water column also significantly affected prey-capture success, as individuals' experienced two-fold greater success when attacking prey while submerged. These estimates are the first for wild adult American alligators and one of the few examples for any crocodilian species worldwide. More broadly, these results reveal that our understandings of crocodilian foraging behaviors are biased due to previous studies containing limited observations of cryptic and nocturnal foraging interactions. Our results can be used to inform greater understanding regarding the top-down effects of American alligators in estuarine food webs. Additionally, our results highlight the importance and power of using animal-borne imaging when

  2. Animal-Borne Imaging Reveals Novel Insights into the Foraging Behaviors and Diel Activity of a Large-Bodied Apex Predator, the American Alligator (Alligator mississippiensis)

    PubMed Central

    Nifong, James C.; Nifong, Rachel L.; Silliman, Brian R.; Lowers, Russell H.; Guillette, Louis J.; Ferguson, Jake M.; Welsh, Matthew; Abernathy, Kyler; Marshall, Greg

    2014-01-01

    Large-bodied, top- and apex predators (e.g., crocodilians, sharks, wolves, killer whales) can exert strong top-down effects within ecological communities through their interactions with prey. Due to inherent difficulties while studying the behavior of these often dangerous predatory species, relatively little is known regarding their feeding behaviors and activity patterns, information that is essential to understanding their role in regulating food web dynamics and ecological processes. Here we use animal-borne imaging systems (Crittercam) to study the foraging behavior and activity patterns of a cryptic, large-bodied predator, the American alligator (Alligator mississippiensis) in two estuaries of coastal Florida, USA. Using retrieved video data we examine the variation in foraging behaviors and activity patterns due to abiotic factors. We found the frequency of prey-attacks (mean = 0.49 prey attacks/hour) as well as the probability of prey-capture success (mean = 0.52 per attack) were significantly affected by time of day. Alligators attempted to capture prey most frequently during the night. Probability of prey-capture success per attack was highest during morning hours and sequentially lower during day, night, and sunset, respectively. Position in the water column also significantly affected prey-capture success, as individuals’ experienced two-fold greater success when attacking prey while submerged. These estimates are the first for wild adult American alligators and one of the few examples for any crocodilian species worldwide. More broadly, these results reveal that our understandings of crocodilian foraging behaviors are biased due to previous studies containing limited observations of cryptic and nocturnal foraging interactions. Our results can be used to inform greater understanding regarding the top-down effects of American alligators in estuarine food webs. Additionally, our results highlight the importance and power of using animal

  3. NPM-ALK oncogenic kinase promotes cell-cycle progression through activation of JNK/cJun signaling in anaplastic large-cell lymphoma.

    PubMed

    Leventaki, Vasiliki; Drakos, Elias; Medeiros, L Jeffrey; Lim, Megan S; Elenitoba-Johnson, Kojo S; Claret, Francois X; Rassidakis, George Z

    2007-09-01

    Anaplastic large-cell lymphoma (ALCL) frequently carries the t(2;5)(p23;q35), resulting in aberrant expression of nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). We show that in 293T and Jurkat cells, forced expression of active NPM-ALK, but not kinase-dead mutant NPM-ALK (210K>R), induced JNK and cJun phosphorylation, and this was linked to a dramatic increase in AP-1 transcriptional activity. Conversely, inhibition of ALK activity in NPM-ALK(+) ALCL cells resulted in a concentration-dependent dephosphorylation of JNK and cJun and decreased AP-1 DNA-binding. In addition, JNK physically binds NPM-ALK and is highly activated in cultured and primary NPM-ALK(+) ALCL cells. cJun phosphorylation in NPM-ALK(+) ALCL cells is mediated by JNKs, as shown by selective knocking down of JNK1 and JNK2 genes using siRNA. Inhibition of JNK activity using SP600125 decreased cJun phosphorylation and AP-1 transcriptional activity and this was associated with decreased cell proliferation and G2/M cell-cycle arrest in a dose-dependent manner. Silencing of the cJun gene by siRNA led to a decreased S-phase cell-cycle fraction associated with upregulation of p21 and downregulation of cyclin D3 and cyclin A. Taken together, these findings reveal a novel function of NPM-ALK, phosphorylation and activation of JNK and cJun, which may contribute to uncontrolled cell-cycle progression and oncogenesis.

  4. Functional link between muscarinic receptors and large-conductance Ca2+ -activated K+ channels in freshly isolated human detrusor smooth muscle cells.

    PubMed

    Parajuli, Shankar P; Hristov, Kiril L; Cheng, Qiuping; Malysz, John; Rovner, Eric S; Petkov, Georgi V

    2015-04-01

    Activation of muscarinic acetylcholine receptors (mAChRs) constitutes the primary mechanism for enhancing excitability and contractility of human detrusor smooth muscle (DSM). Since the large-conductance Ca(2+)-activated K(+) (KCa1.1) channels are key regulators of human DSM function, we investigated whether mAChR activation increases human DSM excitability by inhibiting KCa1.1 channels. We used the mAChR agonist, carbachol, to determine the changes in KCa1.1 channel activity upon mAChR activation in freshly isolated human DSM cells obtained from open bladder surgeries using the perforated whole cell and single KCa1.1 channel patch-clamp recordings. Human DSM cells were collected from 29 patients (23 males and 6 females, average age of 65.9 ± 1.5 years). Carbachol inhibited the amplitude and frequency of KCa1.1 channel-mediated spontaneous transient outward currents and spontaneous transient hyperpolarizations, which are triggered by the release of Ca(2+) from ryanodine receptors. Carbachol also caused membrane potential depolarization, which was not observed in the presence of iberiotoxin, a KCa1.1 channel inhibitor, indicating the critical role of the KCa1.1 channels. The potential direct carbachol effects on KCa1.1 channels were examined under conditions of removing the major cellular Ca(2+) sources for KCa1.1 channel activation with pharmacological inhibitors (thapsigargin, ryanodine, and nifedipine). In the presence of these inhibitors, carbachol did not affect the single KCa1.1 channel open probability and mean KCa1.1 channel conductance (cell-attached configuration) or depolarization-induced whole cell steady-state KCa1.1 currents. The data support the concept that mAChR activation triggers indirect functional KCa1.1 channel inhibition mediated by intracellular Ca(2+), thus increasing the excitability in human DSM cells.

  5. Activation of the STAT3 Signaling Pathway Is Associated With Poor Survival in Diffuse Large B-Cell Lymphoma Treated With R-CHOP

    PubMed Central

    Huang, Xin; Meng, Bin; Iqbal, Javeed; Ding, B. Belinda; Perry, Anamarija M.; Cao, Wenfeng; Smith, Lynette M.; Bi, Chengfeng; Jiang, Chunsun; Greiner, Timothy C.; Weisenburger, Dennis D.; Rimsza, Lisa; Rosenwald, Andreas; Ott, German; Delabie, Jan; Campo, Elias; Braziel, Rita M.; Gascoyne, Randy D.; Cook, James R.; Tubbs, Raymond R.; Jaffe, Elaine S.; Armitage, James O.; Vose, Julie M.; Staudt, Louis M.; McKeithan, Timothy W.; Chan, Wing C.; Ye, B. Hilda; Fu, Kai

    2013-01-01

    Purpose We previously reported that constitutive STAT3 activation is a prominent feature of the activated B-cell subtype of diffuse large B-cell lymphomas (ABC-DLBCL). In this study, we investigated whether STAT3 activation can risk stratify patients with DLBCL. Patients and Methods By an immunohistochemical method, we investigated phosphotyrosine STAT3 (PY-STAT3) expression from 185 patients with DLBCL treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone). Cell line-based siRNA experiments were also performed to generate an 11-gene, PY-STAT3 activation signature, which was used to study a previously published cohort of 222 patients with DLBCL. The STAT3 activation status determined by these two methods and by STAT3 mRNA levels were then correlated with survival. Results PY-STAT3 was detected in 37% of DLBCL and enriched in ABC-DLBCL cases (P = .03). PY-STAT3 positivity significantly correlated with poor overall survival (OS; P = .01) and event-free survival (EFS; P = .006). Similar observations were made for high levels of STAT3 mRNA. In multivariable analysis, PY-STAT3 status (P = .02), International Prognostic Index (P = .02), and BCL2 expression (P = .046) were independent prognosticators of OS in this cohort. Among the cell-of-origin subgroups, PY-STAT3 was associated with poor EFS among non–germinal center B-cell DLBCL cases only (P = .027). Similarly, the 11-gene STAT3 activation signature correlated with poor survival in the entire DLBCL cohort (OS, P < .001; EFS, P < .001) as well as the ABC-DLBCL subgroup (OS, P = .029; EFS, P = .025). Conclusion STAT3 activation correlated with poor survival in patients with DLBCL treated with R-CHOP, especially those with tumors of the ABC-DLBCL subtype. PMID:24220563

  6. Binary classification of a large collection of environmental chemicals from estrogen receptor assays by quantitative structure-activity relationship and machine learning methods.

    PubMed

    Zang, Qingda; Rotroff, Daniel M; Judson, Richard S

    2013-12-23

    There are thousands of environmental chemicals subject to regulatory decisions for endocrine disrupting potential. The ToxCast and Tox21 programs have tested ∼8200 chemicals in a broad screening panel of in vitro high-throughput screening (HTS) assays for estrogen receptor (ER) agonist and antagonist activity. The present work uses this large data set to develop in silico quantitative structure-activity relationship (QSAR) models using machine learning (ML) methods and a novel approach to manage the imbalanced data distribution. Training compounds from the ToxCast project were categorized as active or inactive (binding or nonbinding) classes based on a composite ER Interaction Score derived from a collection of 13 ER in vitro assays. A total of 1537 chemicals from ToxCast were used to derive and optimize the binary classification models while 5073 additional chemicals from the Tox21 project, evaluated in 2 of the 13 in vitro assays, were used to externally validate the model performance. In order to handle the imbalanced distribution of active and inactive chemicals, we developed a cluster-selection strategy to minimize information loss and increase predictive performance and compared this strategy to three currently popular techniques: cost-sensitive learning, oversampling of the minority class, and undersampling of the majority class. QSAR classification models were built to relate the molecular structures of chemicals to their ER activities using linear discriminant analysis (LDA), classification and regression trees (CART), and support vector machines (SVM) with 51 molecular descriptors from QikProp and 4328 bits of structural fingerprints as explanatory variables. A random forest (RF) feature selection method was employed to extract the structural features most relevant to the ER activity. The best model was obtained using SVM in combination with a subset of descriptors identified from a large set via the RF algorithm, which recognized the active and

  7. Binary classification of a large collection of environmental chemicals from estrogen receptor assays by quantitative structure-activity relationship and machine learning methods.

    PubMed

    Zang, Qingda; Rotroff, Daniel M; Judson, Richard S

    2013-12-23

    There are thousands of environmental chemicals subject to regulatory decisions for endocrine disrupting potential. The ToxCast and Tox21 programs have tested ∼8200 chemicals in a broad screening panel of in vitro high-throughput screening (HTS) assays for estrogen receptor (ER) agonist and antagonist activity. The present work uses this large data set to develop in silico quantitative structure-activity relationship (QSAR) models using machine learning (ML) methods and a novel approach to manage the imbalanced data distribution. Training compounds from the ToxCast project were categorized as active or inactive (binding or nonbinding) classes based on a composite ER Interaction Score derived from a collection of 13 ER in vitro assays. A total of 1537 chemicals from ToxCast were used to derive and optimize the binary classification models while 5073 additional chemicals from the Tox21 project, evaluated in 2 of the 13 in vitro assays, were used to externally validate the model performance. In order to handle the imbalanced distribution of active and inactive chemicals, we developed a cluster-selection strategy to minimize information loss and increase predictive performance and compared this strategy to three currently popular techniques: cost-sensitive learning, oversampling of the minority class, and undersampling of the majority class. QSAR classification models were built to relate the molecular structures of chemicals to their ER activities using linear discriminant analysis (LDA), classification and regression trees (CART), and support vector machines (SVM) with 51 molecular descriptors from QikProp and 4328 bits of structural fingerprints as explanatory variables. A random forest (RF) feature selection method was employed to extract the structural features most relevant to the ER activity. The best model was obtained using SVM in combination with a subset of descriptors identified from a large set via the RF algorithm, which recognized the active and

  8. One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

    PubMed

    Ye, Sunjie; Benz, Felix; Wheeler, May C; Oram, Joseph; Baumberg, Jeremy J; Cespedes, Oscar; Christenson, Hugo K; Coletta, Patricia Louise; Jeuken, Lars J C; Markham, Alexander F; Critchley, Kevin; Evans, Stephen D

    2016-08-11

    Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications.

  9. One-step fabrication of hollow-channel gold nanoflowers with excellent catalytic performance and large single-particle SERS activity.

    PubMed

    Ye, Sunjie; Benz, Felix; Wheeler, May C; Oram, Joseph; Baumberg, Jeremy J; Cespedes, Oscar; Christenson, Hugo K; Coletta, Patricia Louise; Jeuken, Lars J C; Markham, Alexander F; Critchley, Kevin; Evans, Stephen D

    2016-08-11

    Hollow metallic nanostructures have shown potential in various applications including catalysis, drug delivery and phototherapy, owing to their large surface areas, reduced net density, and unique optical properties. In this study, novel hollow gold nanoflowers (HAuNFs) consisting of an open hollow channel in the center and multiple branches/tips on the outer surface are fabricated for the first time, via a facile one-step synthesis using an auto-degradable nanofiber as a bifunctional template. The one-dimensional (1D) nanofiber acts as both a threading template as well as a promoter of the anisotropic growth of the gold crystal, the combination of which leads to the formation of HAuNFs with a hollow channel and nanospikes. The synergy of favorable structural/surface features, including sharp edges, open cavity and high-index facets, provides our HAuNFs with excellent catalytic performance (activity and cycling stability) coupled with large single-particle SERS activity (including ∼30 times of activity in ethanol electro-oxidation and ∼40 times of single-particle SERS intensity, benchmarked against similar-sized solid gold nanospheres with smooth surfaces, as well as retaining 86.7% of the initial catalytic activity after 500 cycles in ethanol electro-oxidation). This innovative synthesis gives a nanostructure of the geometry distinct from the template and is extendable to fabricating other systems for example, hollow-channel silver nanoflowers (HAgNFs). It thus provides an insight into the design of hollow nanostructures via template methods, and offers a versatile synthetic strategy for diverse metal nanomaterials suited for a broad range of applications. PMID:27352044

  10. Torsion sensing with a fiber ring laser incorporating a pair of rotary long-period fiber gratings

    NASA Astrophysics Data System (ADS)

    Shi, Leilei; Zhu, Tao; Fan, Yan-en; Chiang, Kin Seng; Rao, Yunjiang

    2011-10-01

    We experimentally demonstrate a fiber ring laser for high-resolution torsion measurement, where the laser cavity consists of a Mach-Zehnder interferometer formed with a pair of long-period fiber gratings written in a twisted single-mode fiber by a CO 2 laser. The emitting wavelength of the laser provides a measure of the rate of the torsion applied to the grating pair, while the direction of the wavelength shift indicates the sense of the applied torsion. The narrow linewidth and the large side-mode suppression ratio of the laser can provide a much more precise measurement of torsion, compared with passive fiber-optic torsion sensors. The torsion sensitivity achieved is 0.084 nm/(rad/m) in the torsion range ± 100 rad/m, which corresponds to a torsion resolution of 0.12 rad/m, assuming a wavelength resolution of 10 pm for a typical optical spectrum analyzer. The ultimate resolution of the sensor is limited by the linewidth of the laser and could be an order of magnitude higher.

  11. Use of a Web-Based Physical Activity Record System to Analyze Behavior in a Large Population: Cross-Sectional Study

    PubMed Central

    Yamada, Yosuke; Ishida, Mika; Takase, Hideto; Kimura, Misaka

    2015-01-01

    Background The use of Web-based physical activity systems has been proposed as an easy method for collecting physical activity data. We have developed a system that has exhibited high accuracy as assessed by the doubly labeled water method. Objective The purpose of this study was to collect behavioral data from a large population using our Web-based physical activity record system and assess the physical activity of the population based on these data. In this paper, we address the difference in physical activity for each urban scale. Methods In total, 2046 participants (aged 30-59 years; 1105 men and 941 women) participated in the study. They were asked to complete data entry before bedtime using their personal computer on 1 weekday and 1 weekend day. Their residential information was categorized as urban, urban-rural, or rural. Participant responses expressed the intensity of each activity at 15-minute increments and were recorded on a Web server. Residential areas were compared and multiple regression analysis was performed. Results Most participants had a metabolic equivalent (MET) ranging from 1.4 to 1.8, and the mean MET was 1.60 (SD 0.28). The median value of moderate-to-vigorous physical activity (MVPA, ≥3 MET) was 7.92 MET-hours/day. A 1-way ANCOVA showed that total physical activity differed depending on the type of residential area (F2,2027=5.19, P=.006). The urban areas (n=950) had the lowest MET-hours/day (mean 37.8, SD, 6.0), followed by urban-rural areas (n=432; mean 38.6, SD 6.5; P=.04), and rural areas (n=664; mean 38.8, SD 7.4; P=.002). Two-way ANCOVA showed a significant interaction between sex and area of residence on the urban scale (F2,2036=4.53, P=.01). Men in urban areas had the lowest MET-hours/day (MVPA, ≥3 MET) at mean 7.9 (SD 8.7); men in rural areas had a MET-hours/day (MVPA, ≥3 MET) of mean 10.8 (SD 12.1, P=.002). No significant difference was noted in women among the 3 residential areas. Multiple regression analysis showed that

  12. Omacetaxine mepesuccinate induces apoptosis and cell cycle arrest, promotes cell differentiation, and reduces telomerase activity in diffuse large B-cell lymphoma cells

    PubMed Central

    ZHANG, LINA; CHEN, ZHENZHU; ZUO, WENLI; ZHU, XINGHU; LI, YUFU; LIU, XINJIAN; WEI, XUDONG

    2016-01-01

    Clinical studies have demonstrated that omacetaxine mepesuccinate exerts beneficial effects on acute myelogenous leukemia. It has been suggested that omacetaxine mepesuccinate, used alone or with interferon-α or cytarabine, induces remission in patients with chronic myelogenous leukemia. These effects are possibly mediated by its ability to induce apoptosis of leukemia cells and inhibit the activity of telomerase. To determine whether omacetaxine mepesuccinate is beneficial in diffuse large B-cell lymphoma (DLBCL), two DLBCL cell lines [a germinal center B cell-like subtype (GCB) and an activated B cell-like subtype (ABC)] were treated with omacetaxine mepesuccinate at various concentrations for different durations. The present study indicated that omacetaxine mepesuccinate exerts proapoptotic effects in the two cell types in a dose- and time-dependent manner. The ABC subtype demonstrated increased sensitivity compared with the GCB subtype. At 40 ng/ml, omacetaxine mepesuccinate exhibited a marked proapoptotic effect on DLBCL cells compared with the other tumor cells investigated. Furthermore, omacetaxine mepesuccinate induced cell cycle arrest at G0/G1 phase, and promoted cell terminal differentiation of pro-B cells. The present study also demonstrated that omacetaxine mepesuccinate exerted its antitumor effect by reducing telomerase activity. In conclusion, the present study demonstrated that omacetaxine mepesuccinate may induce apoptosis and cell cycle arrest, promote cell differentiation, and reduce telomerase activity in DLBCL cells, thus aiding the development of omacetaxine mepesuccinate-based DLBCL therapeutic strategies. PMID:26935769

  13. Cooperative signaling through the signal transducer and activator of transcription 3 and nuclear factor-κB pathways in subtypes of diffuse large B-cell lymphoma

    PubMed Central

    Lam, Lloyd T.; Wright, George; Davis, R. Eric; Lenz, Georg; Farinha, Pedro; Dang, Lenny; Chan, John W.; Rosenwald, Andreas; Gascoyne, Randy D.

    2008-01-01

    The activated B cell–like (ABC) subgroup of diffuse large B-cell lymphoma (DLBCL) is characterized by constitutive activation of the nuclear factor-κB (NF-κB) pathway. In this study, we showed that the NF-κB pathway induced the expression of the cytokines interleukin (IL)-6 and IL-10 in ABC DLBCL cell lines, which also have high levels of total and phosphorylated signal transducer and activator of transcription (STAT) 3 protein, suggesting autocrine signaling. Using RNA interference for STAT3, we defined a gene expression signature of IL-6 and IL-10 signaling through STAT3. Based on this signature, we constructed a molecular predictor of STAT3 signaling that defined a subset of ABC DLBCL tumors with high expression of STAT3, IL-6, and/or IL-10 and their downstream targets. Although the STAT3-high and STAT3-low subsets had equivalent expression of genes that distinguish ABC DLBCL from germinal center B cell–like DLBCL, STAT3-high ABC DLBCLs had higher expression of signatures that reflected NF-κB activity, proliferation, and glycolysis. A small-molecule inhibitor of Janus kinase signaling, which blocked STAT3 signature expression, was toxic only for ABC DLBCL lines and synergized with an inhibitor of NF-κB signaling. These findings suggest that the biological interplay between the STAT3 and NF-κB pathways may be exploited for the treatments of a subset of ABC DLBCLs. PMID:18160665

  14. Hepatitis B virus PreS2-mutant large surface antigen activates store-operated calcium entry and promotes chromosome instability

    PubMed Central

    Yen, Tim Ting-Chung; Yang, Anderson; Chiu, Wen-Tai; Li, Tian-Neng; Wang, Lyu-Han; Wu, Yi-Hsuan; Wang, Hui-Chen; Chen, Linyi; Wang, Wen-Ching; Huang, Wenya; Chang, Chien-Wen; Chang, Margaret Dah-Tsyr; Shen, Meng-Ru; Su, Ih-Jen; Wang, Lily Hui-Ching

    2016-01-01

    Hepatitis B virus (HBV) is a driver of hepatocellular carcinoma, and two viral products, X and large surface antigen (LHBS), are viral oncoproteins. During chronic viral infection, immune-escape mutants on the preS2 region of LHBS (preS2-LHBS) are gain-of-function mutations that are linked to preneoplastic ground glass hepatocytes (GGHs) and early disease onset of hepatocellular carcinoma. Here, we show that preS2-LHBS provoked calcium release from the endoplasmic reticulum (ER) and triggered stored-operated calcium entry (SOCE). The activation of SOCE increased ER and plasma membrane (PM) connections, which was linked by ER- resident stromal interaction molecule-1 (STIM1) protein and PM-resident calcium release- activated calcium modulator 1 (Orai1). Persistent activation of SOCE induced centrosome overduplication, aberrant multipolar division, chromosome aneuploidy, anchorage-independent growth, and xenograft tumorigenesis in hepatocytes expressing preS2- LHBS. Chemical inhibitions of SOCE machinery and silencing of STIM1 significantly reduced centrosome numbers, multipolar division, and xenograft tumorigenesis induced by preS2-LHBS. These results provide the first mechanistic link between calcium homeostasis and chromosome instability in hepatocytes carrying preS2-LHBS. Therefore, persistent activation of SOCE represents a novel pathological mechanism in HBV-mediated hepatocarcinogenesis. PMID:26992221

  15. ALK kinase domain mutations in primary anaplastic large cell lymphoma: consequences on NPM-ALK activity and sensitivity to tyrosine kinase inhibitors.

    PubMed

    Lovisa, Federica; Cozza, Giorgio; Cristiani, Andrea; Cuzzolin, Alberto; Albiero, Alessandro; Mussolin, Lara; Pillon, Marta; Moro, Stefano; Basso, Giuseppe; Rosolen, Angelo; Bonvini, Paolo

    2015-01-01

    ALK inhibitor crizotinib has shown potent antitumor activity in children with refractory Anaplastic Large Cell Lymphoma (ALCL) and the opportunity to include ALK inhibitors in first-line therapies is oncoming. However, recent studies suggest that crizotinib-resistance mutations may emerge in ALCL patients. In the present study, we analyzed ALK kinase domain mutational status of 36 paediatric ALCL patients at diagnosis to identify point mutations and gene aberrations that could impact on NPM-ALK gene expression, activity and sensitivity to small-molecule inhibitors. Amplicon ultra-deep sequencing of ALK kinase domain detected 2 single point mutations, R335Q and R291Q, in 2 cases, 2 common deletions of exon 23 and 25 in all the patients, and 7 splicing-related INDELs in a variable number of them. The functional impact of missense mutations and INDELs was evaluated. Point mutations were shown to affect protein kinase activity, signalling output and drug sensitivity. INDELs, instead, generated kinase-dead variants with dominant negative effect on NPM-ALK kinase, in virtue of their capacity of forming non-functional heterocomplexes. Consistently, when co-expressed, INDELs increased crizotinib inhibitory activity on NPM-ALK signal processing, as demonstrated by the significant reduction of STAT3 phosphorylation. Functional changes in ALK kinase activity induced by both point mutations and structural rearrangements were resolved by molecular modelling and dynamic simulation analysis, providing novel insights into ALK kinase domain folding and regulation. Therefore, these data suggest that NPM-ALK pre-therapeutic mutations may be found at low frequency in ALCL patients. These mutations occur randomly within the ALK kinase domain and affect protein activity, while preserving responsiveness to crizotinib.

  16. Identification of one novel candidate probiotic Lactobacillus plantarum strain active against influenza virus infection in mice by a large-scale screening.

    PubMed

    Kechaou, Noura; Chain, Florian; Gratadoux, Jean-Jacques; Blugeon, Sébastien; Bertho, Nicolas; Chevalier, Christophe; Le Goffic, Ronan; Courau, Stéphanie; Molimard, Pascal; Chatel, Jean Marc; Langella, Philippe; Bermúdez-Humarán, Luis G

    2013-03-01

    In this study, we developed a large-scale screening of bacterial strains in order to identify novel candidate probiotics with immunomodulatory properties. For this, 158 strains, including a majority of lactic acid bacteria (LAB), were screened by two different cellular models: tumor necrosis factor alpha (TNF-α)-activated HT-29 cells and peripheral blood mononuclear cells (PBMCs). Different strains responsive to both models (pro- and anti-inflammatory strains) were selected, and their protective effects were tested in vivo in a murine model of influenza virus infection. Daily intragastric administrations during 10 days before and 10 days after viral challenge (100 PFU of influenza virus H1N1 strain A Puerto Rico/8/1934 [A/PR8/34]/mouse) of Lactobacillus plantarum CNRZ1997, one potentially proinflammatory probiotic strain, led to a significant improvement in mouse health by reducing weight loss, alleviating clinical symptoms, and inhibiting significantly virus proliferation in lungs. In conclusion, in this study, we have combined two cellular models to allow the screening of a large number of LAB for their immunomodulatory properties. Moreover, we identified a novel candidate probiotic strain, L. plantarum CNRZ1997, active against influenza virus infection in mice.

  17. Identification of One Novel Candidate Probiotic Lactobacillus plantarum Strain Active against Influenza Virus Infection in Mice by a Large-Scale Screening

    PubMed Central

    Kechaou, Noura; Chain, Florian; Gratadoux, Jean-Jacques; Blugeon, Sébastien; Bertho, Nicolas; Chevalier, Christophe; Le Goffic, Ronan; Courau, Stéphanie; Molimard, Pascal; Chatel, Jean Marc

    2013-01-01

    In this study, we developed a large-scale screening of bacterial strains in order to identify novel candidate probiotics with immunomodulatory properties. For this, 158 strains, including a majority of lactic acid bacteria (LAB), were screened by two different cellular models: tumor necrosis factor alpha (TNF-α)-activated HT-29 cells and peripheral blood mononuclear cells (PBMCs). Different strains responsive to both models (pro- and anti-inflammatory strains) were selected, and their protective effects were tested in vivo in a murine model of influenza virus infection. Daily intragastric administrations during 10 days before and 10 days after viral challenge (100 PFU of influenza virus H1N1 strain A Puerto Rico/8/1934 [A/PR8/34]/mouse) of Lactobacillus plantarum CNRZ1997, one potentially proinflammatory probiotic strain, led to a significant improvement in mouse health by reducing weight loss, alleviating clinical symptoms, and inhibiting significantly virus proliferation in lungs. In conclusion, in this study, we have combined two cellular models to allow the screening of a large number of LAB for their immunomodulatory properties. Moreover, we identified a novel candidate probiotic strain, L. plantarum CNRZ1997, active against influenza virus infection in mice. PMID:23263960

  18. Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

    NASA Astrophysics Data System (ADS)

    Sun, Fei; Gao, Jihui; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

    2016-11-01

    Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m2 g-1) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g-1 at 0.5 A g-1 and still 120 F g-1 at a high rate of 30 A g-1. There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg-1 and 4.03 Wh kg-1 with the corresponding power densities of 108 W kg-1 and 6.49 kW kg-1, respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

  19. New results about the study of the lightning activity and characteristics over the large urban area of the city of São Paulo

    NASA Astrophysics Data System (ADS)

    Farias, W. R.; Pinto, O.; Pinto, I. R.

    2009-12-01

    The urban effect on lightning activity has been studied in many places around the world. The Metropolitan Region of São Paulo (MRSP) in the Southeast region of Brazil is one of the greatest and more populous urban areas of the world with a density of about 3000 inhabitants/km2. Similar to observations in other large urban areas, there is a significant enhancement in the number of negative cloud-to-ground (CG) lightning and a decrease in the percentage of positive CG flashes over the city of São Paulo. This work investigates the role of air polluted on lightning in MRSP. The CG lightning data set used was provided by Brazilian lightning detection network (BrasilDAT) for a period of 10 years (1999 - 2008). In this period, only days with CG flashes during the spring and summer seasons (from October to March) were considered and, for these days, only lightning data from 14 h to 20 h LT, were considered since this period corresponds to the time of the day with maximum lightning activity. The air polluted data set used in this work, was provided by the São Paulo environmental agencies (CETESB). The main results are: there is a tendency of increase in the ratio between lightning activity in the center area and surrounding area of the MRSP during the ten years in agreement with the same tendency observed for the number of automotive vehicles circulating on the center area of the city; there is a statistical significant increase in the CG lightning activity during the week days over MRSP related to the PM10 concentration. Apparently the increase in the lightning activity is related to an increase in the lifetime of the storms and, in consequence, the number of flashes per storm, and not to the mean flash rate of the storms. However, the increase also suggest that the effect of the pollution in the enhancement of the CG lightning activity is probably less significant compared to the effect of the urban heat island. A similar study is being done for other lightning spot

  20. Thinking large.

    PubMed

    Devries, Egbert

    2016-05-01

    Egbert Devries was brought up on a farm in the Netherlands and large animal medicine has always been his area of interest. After working in UK practice for 12 years he joined CVS and was soon appointed large animal director with responsibility for building a stronger large animal practice base. PMID:27154956

  1. Non-destructive elemental analysis of large meteorite samples by prompt gamma-ray neutron activation analysis with the internal mono-standard method.

    PubMed

    Latif, Sk A; Oura, Y; Ebihara, M; Nakahara, H

    2013-11-01

    Prompt gamma-ray neutron activation analysis (PGNAA) using the internal mono-standard method was tested for its applicability to analyzing large solid samples including irregularly shaped meteorite samples. For evaluating the accuracy and precision of the method, large quantities of the Geological Survey of Japan standardized rock powders (JB-1a, JG-1a, and JP-1) were analyzed and 12 elements (B, Na, Mg, Al, Cl, K, Ca, Ti, Mn, Fe, Sm, and Gd) were determined by using Si as an internal standard element. Analytical results were mostly in agreement with literature values within 10 %. The precision of the method was also shown to be within 10 % (1σ) for most of these elements. The analytical procedure was then applied to four stony meteorites (Allende, Kimble County, Leedey, Lake Labyrinth) and four iron meteorites (Canyon Diablo, Toluca (Mexico), Toluca (Xiquipilco), Squaw Creek) consisting of large chunks or single slabs. For stony meteorites, major elements (Mg, Al, Si, S, Ca, and Ni), minor elements (Na and Mn) and trace element (B, Cl, K, Ti, Co, and Sm) were determined with adequate accuracy. For iron meteorites, results for the Co and Ni mass fractions determined are all consistent with corresponding literature values. After the analysis, it was confirmed that the residual radioactivity remaining in the sample after PGNAA was very low and decreased down to the background level. This study shows that PGNAA with the internal mono-standard method is highly practical for determining the elemental composition of large, irregularly shaped solid samples including meteorites.

  2. Non-destructive elemental analysis of large meteorite samples by prompt gamma-ray neutron activation analysis with the internal mono-standard method.

    PubMed

    Latif, Sk A; Oura, Y; Ebihara, M; Nakahara, H

    2013-11-01

    Prompt gamma-ray neutron activation analysis (PGNAA) using the internal mono-standard method was tested for its applicability to analyzing large solid samples including irregularly shaped meteorite samples. For evaluating the accuracy and precision of the method, large quantities of the Geological Survey of Japan standardized rock powders (JB-1a, JG-1a, and JP-1) were analyzed and 12 elements (B, Na, Mg, Al, Cl, K, Ca, Ti, Mn, Fe, Sm, and Gd) were determined by using Si as an internal standard element. Analytical results were mostly in agreement with literature values within 10 %. The precision of the method was also shown to be within 10 % (1σ) for most of these elements. The analytical procedure was then applied to four stony meteorites (Allende, Kimble County, Leedey, Lake Labyrinth) and four iron meteorites (Canyon Diablo, Toluca (Mexico), Toluca (Xiquipilco), Squaw Creek) consisting of large chunks or single slabs. For stony meteorites, major elements (Mg, Al, Si, S, Ca, and Ni), minor elements (Na and Mn) and trace element (B, Cl, K, Ti, Co, and Sm) were determined with adequate accuracy. For iron meteorites, results for the Co and Ni mass fractions determined are all consistent with corresponding literature values. After the analysis, it was confirmed that the residual radioactivity remaining in the sample after PGNAA was very low and decreased down to the background level. This study shows that PGNAA with the internal mono-standard method is highly practical for determining the elemental composition of large, irregularly shaped solid samples including meteorites. PMID:24037616

  3. A Fiber-Coupled Self-Mixing Laser Diode for the Measurement of Young's Modulus.

    PubMed

    Lin, Ke; Yu, Yanguang; Xi, Jiangtao; Li, Huijun; Guo, Qinghua; Tong, Jun; Su, Lihong

    2016-01-01

    This paper presents the design of a fiber-coupled self-mixing laser diode (SMLD) for non-contact and non-destructive measurement of Young's modulus. By the presented measuring system, the Young's modulus of aluminum 6061 and brass are measured as 70.0 GPa and 116.7 GPa, respectively, showing a good agreement within the standards in the literature and yielding a much smaller deviation and a higher repeatability compared with traditional tensile testing. Its fiber-coupled characteristics make the system quite easy to be installed in many application cases. PMID:27338413

  4. A Fiber-Coupled Self-Mixing Laser Diode for the Measurement of Young's Modulus.

    PubMed

    Lin, Ke; Yu, Yanguang; Xi, Jiangtao; Li, Huijun; Guo, Qinghua; Tong, Jun; Su, Lihong

    2016-06-22

    This paper presents the design of a fiber-coupled self-mixing laser diode (SMLD) for non-contact and non-destructive measurement of Young's modulus. By the presented measuring system, the Young's modulus of aluminum 6061 and brass are measured as 70.0 GPa and 116.7 GPa, respectively, showing a good agreement within the standards in the literature and yielding a much smaller deviation and a higher repeatability compared with traditional tensile testing. Its fiber-coupled characteristics make the system quite easy to be installed in many application cases.

  5. A fiber-optic cure monitoring technique with accuracy improvement of distorted embedded sensors

    NASA Astrophysics Data System (ADS)

    Sampath, Umesh; Kim, Hyunjin; Kim, Dae-gil; Song, Minho

    2015-07-01

    A fiber-optic epoxy cure monitoring technique for efficient wind turbine blade manufacturing and monitoring is presented. To optimize manufacturing cycle, fiber-optic sensors are embedded in composite materials of wind turbine blades. The reflection spectra of the sensors indicate the onset of gelification and the completion of epoxy curing. After manufacturing process, the same sensors are utilized for in-field condition monitoring. Because of residual stresses and strain gradients from the curing process, the embedded sensors may experience distortions in reflection spectra, resulting in measurement errors. We applied a Gaussian curve-fitting algorithm to the distorted spectra, which substantially improved the measurement accuracy.

  6. Distributed parameter model for characterizing magnetic crosstalk in a fiber optic current sensor.

    PubMed

    Cheng, Song; Guo, Zhi-Zhong; Zhang, Guo-Qing; Yu, Wen-Bin; Shen, Yan

    2015-12-01

    The effects of magnetic crosstalk on a fiber optic current sensor are studied using the distributed parameter model. A new method to enhance the immunity to magnetic crosstalk is proposed. The experimental results show that magnetic crosstalk changes periodically with the azimuth angle and decreases as the distance between the conductors increases. When the sensing coil is placed at the optimal azimuth angle, the ratio error from magnetic crosstalk decreases from -0.32% to -0.02%, demonstrating the effectiveness of the proposed method. PMID:26836653

  7. Generalized Magneto-thermoelasticity in a Fiber-Reinforced Anisotropic Half-Space

    NASA Astrophysics Data System (ADS)

    Abbas, Ibrahim A.; Abd-alla, Abo-el-nour N.; Othman, Mohamed I. A.

    2011-05-01

    The propagation of plane waves in a fiber-reinforced, anisotropic thermoelastic half-space proposed by Lord-Shulman under the effect of a magnetic field is discussed. The problem has been solved numerically using a finite element method. Numerical results for the temperature distribution, the displacement components, and the thermal stress are given and illustrated graphically. Comparisons are made with the results predicted by the theory of generalized thermoelasticity with one relaxation time for different values of time. It is found that the reinforcement has a great effect on the distribution of field quantities.

  8. Versatile patterns of multiple rectangular noise-like pulses in a fiber laser.

    PubMed

    Huang, Yu-Qi; Qi, You-Li; Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

    2016-04-01

    We report on the generation of versatile patterns of multiple rectangular noise-like pulses (NLPs) in a fiber laser mode-locked by nonlinear amplifying loop mirror (NALM). Benefiting from the strengthened nonlinear effect of a segment of highly nonlinear fiber (HNLF) in the loop, multiple rectangular NLPs with various patterns are formed depending on the cavity parameter settings. In particular, the multiple rectangular NLPs could possess unequal packet durations, which is different from the conventional multi-soliton patterns. The experimental results contribute to further understanding the characteristics of the rectangular NLP and the dynamics of multi-pulse patterns. PMID:27137025

  9. Characterization of laser-driven shock waves in solids using a fiber optic pressure probe

    DOE PAGES

    Cranch, Geoffrey A.; Lunsford, Robert; Grun, Jacob; Weaver, James; Compton, Steve; May, Mark; Kostinski, Natalie

    2013-11-08

    Measurement of laser-driven shock wave pressure in solid blocks of polymethyl methacrylate is demonstrated using fiber optic pressure probes. Three probes based on a fiber Fabry–Perot, fiber Bragg grating, and interferometric fiber tip sensor are tested and compared. Shock waves are generated using a high-power laser focused onto a thin foil target placed in close proximity to the test blocks. The fiber Fabry–Perot sensor appears capable of resolving the shock front with a rise time of 91 ns. As a result, the peak pressure is estimated, using a separate shadowgraphy measurement, to be 3.4 GPa.

  10. All-fiber amplifier similariton laser based on a fiber Bragg grating filter.

    PubMed

    Olivier, Michel; Gagnon, Mathieu; Duval, Simon; Bernier, Martin; Piché, Michel

    2015-12-01

    This article presents, for the first time to our knowledge, an all-fiber amplifier similariton laser based on a fiber Bragg grating filter. The laser emits 2.9 nJ pulses at a wavelength of 1554 nm with a repetition rate of 31 MHz. The dechirped pulses have a duration of 89 fs. The characteristic features of the pulse profile and spectrum along with the dynamics of the laser are highlighted in representative simulations. These simulations also address the effect of the filter shape and detuning with respect to the gain spectral peak. PMID:26625073

  11. Optical fiber pressure and acceleration sensor fabricated on a fiber endface

    DOEpatents

    Zhu, Yizheng; Wang, Xingwei; Xu, Juncheng; Wang, Anbo

    2006-05-30

    A fiber optic sensor has a hollow tube bonded to the endface of an optical fiber, and a diaphragm bonded to the hollow tube. The fiber endface and diaphragm comprise an etalon cavity. The length of the etalon cavity changes when applied pressure or acceleration flexes the diaphragm. The entire structure can be made of fused silica. The fiber, tube, and diaphragm can be bonded with a fusion splice. The present sensor is particularly well suited for measuring pressure or acceleration in high temperature, high pressure and corrosive environments (e.g., oil well downholes and jet engines). The present sensors are also suitable for use in biological and medical applications.

  12. Analysis of organic solvents and liquid mixtures using a fiber-tip evaporation sensor

    NASA Astrophysics Data System (ADS)

    Preter, Eyal; Donlagic, Denis; Artel, Vlada; Katims, Rachel A.; Sukenik, Chaim N.; Zadok, Avi

    2014-05-01

    The instantaneous size and rate of evaporation of pendant liquid droplets placed on the cleaved facet of a standard fiber are reconstructed based on reflected optical power. Using the evaporation dynamics, the relative contents of ethanol in ethanol-water binary mixtures are assessed with 1% precision and different blends of methanol in gasoline are properly recognized. The latter application, in particular, is significant for the use of alternative fuels in the automotive sector. Also, ten organic solvents are identified based on their evaporation from a fiber facet coated with a hydrophobic, selfassembled monolayer.

  13. A fiber-optic link for pressure control of ion sources

    NASA Astrophysics Data System (ADS)

    Black, K. L.; MacMillan, D. C.; Bastasz, R.

    1987-08-01

    A fiber-optic link providing high-voltage electrical isolation of pressure gauging and control instrumentation associated with a Colutron ion source has been developed. The link transmitter is connected to the control circuitry and is kept at ground potential. The link receiver/modulator is battery operated and attached to a piezoelectric valve located on the ion source, all of which can be biased up to 5 kV. Feedback signals sent via the link control the valve so that constant pressure in the ion source is maintained. The link is simple, compact, and enhances ion source stability and ease of operation.

  14. Arrangement for connecting a fiber-reinforced plastic pipe to a stainless steel flange

    DOEpatents

    Allais, Arnaud; Hoffmann, Ernst

    2008-02-05

    Arrangement for connecting a fiber-reinforced plastic pipe (18) to a stainless steel flange (12, 16), in which the end of the fiber-reinforced plastic pipe (18) is accommodated in a ring-shaped groove (12a, 16a) in the flange (12, 16), the groove conforming to the dimensions of the fiber-reinforced plastic pipe (18), where the gap remaining between the end of the fiber-reinforced plastic pipe (18) and the ring-shaped groove (12a, 16a) is filled with a sealant (19).

  15. Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

    NASA Technical Reports Server (NTRS)

    Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

    2010-01-01

    The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome

  16. Enhanced photocatalytic activity of hexagonal flake-like Bi2S3 / ZnS composites with a large percentage of reactive facets

    NASA Astrophysics Data System (ADS)

    Xiong, Dan-Ni; Huang, Gui-Fang; Zhou, Bing-Xin; Chang, Shengli; Wang, Fei; Huang, Wei-Qing

    2016-08-01

    Selectively exposing surfaces with high reactivity is an effective strategy to enhance the photocatalytic activity of semiconductor photocatalysts. We report the facile synthesis of hexagonal flake-like Bi2S3/ZnS composites with a large percentage of reactive exposed {2 2 1} facets by tuning only the molar ratios of Bi to Zn. The samples exhibit enhanced optical absorption and red shift of absorption edge. The Bi2S3/ZnS composites with hexagon morphology display superior photocatalytic degradation of methylene blue (MB), faster than that with pure Bi2S3 and pure ZnS by a factor of 7.1 and 3.6, respectively. The enhanced photocatalytic activity can be attributed to the highly reactive {2 2 1} exposed facets and the more efficient separation of photogenerated electron–hole pairs is due to the interface of the hetero-junction. Furthermore, a tentative mechanism for photodegradation of MB over Bi2S3/ZnS composites has been proposed involving the photogenerated holes and ṡOH radicals as the main active species, which is confirmed by using different scavengers. The novel constructed Bi2S3/ZnS composite is expected to be an attractive candidate as a photocatalyst for environmental purification and energy conversion.

  17. Activation of Rac1 and the exchange factor Vav3 are involved in NPM-ALK signaling in anaplastic large cell lymphomas.

    PubMed

    Colomba, A; Courilleau, D; Ramel, D; Billadeau, D D; Espinos, E; Delsol, G; Payrastre, B; Gaits-Iacovoni, F

    2008-04-24

    The majority of anaplastic large cell lymphomas (ALCLs) express the nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) fusion protein, which is oncogenic due to its constitutive tyrosine kinase activity. Transformation by NPM-ALK not only increases proliferation, but also modifies cell shape and motility in both lymphoid and fibroblastic cells. We report that the Rac1 GTPase, a known cytoskeletal regulator, is activated by NPM-ALK in ALCL cell lines (Karpas 299 and Cost) and transfected cells (lymphoid Ba/F3 cells, NIH-3T3 fibroblasts). We have identified Vav3 as one of the exchange factors involved in Rac1 activation. Stimulation of Vav3 and Rac1 by NPM-ALK is under the control of Src kinases. It involves formation of a signaling complex between NPM-ALK, pp60(c-src), Lyn and Vav3, in which Vav3 associates with tyrosine 343 of NPM-ALK via its SH2 domain. Moreover, Vav3 is phosphorylated in NPM-ALK positive biopsies from patients suffering from ALCL, demonstrating the pathological relevance of this observation. The use of Vav3-specific shRNA and a dominant negative Rac1 mutant demonstrates the central role of GTPases in NPM-ALK elicited motility and invasion.

  18. Enhanced photocatalytic activity of hexagonal flake-like Bi2S3 / ZnS composites with a large percentage of reactive facets

    NASA Astrophysics Data System (ADS)

    Xiong, Dan-Ni; Huang, Gui-Fang; Zhou, Bing-Xin; Chang, Shengli; Wang, Fei; Huang, Wei-Qing

    2016-08-01

    Selectively exposing surfaces with high reactivity is an effective strategy to enhance the photocatalytic activity of semiconductor photocatalysts. We report the facile synthesis of hexagonal flake-like Bi2S3/ZnS composites with a large percentage of reactive exposed {2 2 1} facets by tuning only the molar ratios of Bi to Zn. The samples exhibit enhanced optical absorption and red shift of absorption edge. The Bi2S3/ZnS composites with hexagon morphology display superior photocatalytic degradation of methylene blue (MB), faster than that with pure Bi2S3 and pure ZnS by a factor of 7.1 and 3.6, respectively. The enhanced photocatalytic activity can be attributed to the highly reactive {2 2 1} exposed facets and the more efficient separation of photogenerated electron-hole pairs is due to the interface of the hetero-junction. Furthermore, a tentative mechanism for photodegradation of MB over Bi2S3/ZnS composites has been proposed involving the photogenerated holes and ṡOH radicals as the main active species, which is confirmed by using different scavengers. The novel constructed Bi2S3/ZnS composite is expected to be an attractive candidate as a photocatalyst for environmental purification and energy conversion.

  19. Technology Development of a Fiber Optic-Coupled Laser Ignition System for Multi-Combustor Rocket Engines

    NASA Technical Reports Server (NTRS)

    Trinh, Huu P.; Early, Jim; Osborne, Robin; Thomas, Matthew E.; Bossard, John A.

    2002-01-01

    This paper addresses the progress of technology development of a laser ignition system at NASA Marshall Space Flight Center (MSFC). The first two years of the project focus on comprehensive assessments and evaluations of a novel dual-pulse laser concept, flight- qualified laser system, and the technology required to integrate the laser ignition system to a rocket chamber. With collaborations of the Department of Energy/Los Alamos National Laboratory (LANL) and CFD Research Corporation (CFDRC), MSFC has conducted 26 hot fire ignition tests with lab-scale laser systems. These tests demonstrate the concept feasibility of dual-pulse laser ignition to initiate gaseous oxygen (GOX)/liquid kerosene (RP-1) combustion in a rocket chamber. Presently, a fiber optic- coupled miniaturized laser ignition prototype is being implemented at the rocket chamber test rig for future testing. Future work is guided by a technology road map that outlines the work required for maturing a laser ignition system. This road map defines activities for the next six years, with the goal of developing a flight-ready laser ignition system.

  20. [Diversity, relative abundance and activity patterns of medium and large mammals in a tropical deciduous forest in the Isthmus of Tehuantepec, Oaxaca, Mexico].

    PubMed

    Cortés-Marcial, Malinalli; Briones-Salas, Miguel

    2014-12-01

    The use of camera traps and mammal track search are complementary methods to monitoring species of which is not well documented their natural history, as in the case of medium and large mammals. To ensure its conservation and good management, it is necessary to generate information about the structure of the community and their populations. The objective of the present study was to estimate the diversity, relative abundance and activity patterns of medium and large mammals in a tropical deciduous forest located in the Isthmus of Tehuantepec, Oaxaca, Mexico. Samplings were conducted in three month intervals, from September 2011 to May 2013. We used photographic-sampling and track search, two complementary sampling methods. For photographic-sampling, 12 camera traps were placed covering an area of 60 km2, while for the tracks search a monthly tour of four line-transect surveys of three kilometers length each was undertaken. We obtained a total of 344 pictures with 5292 trap-days total sampling effort; in addition, 187 track records in a total of 144 km. With both methods we registered 21 species of mammals, in 13 families and seven orders, and five species resulted in new records to the area. The diversity index of Shannon-Wiener obtained with the method of tracks was H' = 2.41, while the most abundant species were Urocyon cinereoargen- teus (IAR = 0.23) and Pecari tajacu (IAR = 0.20). By the method of trap the most abundant species were P. tajacu (IAR = 2.62) and Nasua narica (IAR = 1.28). In terms of patterns of activity P. tajacu, N. narica and Odocoileus virginianus were primarily diurnal species; Canis latrans and Leopardus pardalis did not show preference for any schedule in particular, and Didelphis virginiana and Dasypus novemcinctus preferred to have nocturnal activity. This information can be of help to the creation of programs of management and conservation of mam- mals of medium and large in the Isthmus of Tehuantepec, Oaxaca, México.

  1. Lab-on-a-fiber: building a fiber optic sensing platform for low-cost and high-performance trace vapor TNT detection

    NASA Astrophysics Data System (ADS)

    Ma, Jianjun; Kos, Aldona; Bock, Wojtek J.; Li, Xianzhe; Nguyen, Huy; Wang, Zhi Yuan; Cusano, Andrea

    2010-09-01

    By depositing an amplifying fluorescent polymer (AFP) directly onto the core side wall of an optical fiber near the fiber tip, a functional fiber-optic sensing platform is created at a scale of a mere 0.8×0.8×1.6 mm3, including the second fiber tip for excitation light delivery. The device integrates several functional optical components, a chemical sensory film and the necessary laboratory procedures on a minute scale. Here the Lab-on-a-Fiber (LOF) platform is conceptually introduced and proven to be a high-performance and low-cost approach to detection of trace vapors of TNT explosives. The low-cost potential is achieved by straightforward system construction and simple procedures for the AFP film deposition. The high performance is achieved by a dramatic increase of fluorescence emission signal collection, virtually complete suppression of excitation stray light and the fast response to the presence of TNT vapor, which is illustrated by 30% of quenching percentage occurring within 10 seconds.

  2. Single-channel biophysical and pharmacological characterizations of native human large-conductance calcium-activated potassium channels in freshly isolated detrusor smooth muscle cells.

    PubMed

    Malysz, John; Rovner, Eric S; Petkov, Georgi V

    2013-07-01

    Recent studies have demonstrated the importance of large-conductance Ca(2+)-activated K(+) (BK) channels in detrusor smooth muscle (DSM) function in vitro and in vivo. However, in-depth characterization of human native DSM single BK channels has not yet been provided. Here, we conducted single-channel recordings from excised patches from native human DSM cells. Inside-out and outside-out recordings in high K(+) symmetrical solution (containing 140 mM KCl and ~300 nM free Ca(2+)) showed single-channel conductance of 215-220 pS, half-maximum constant for activation of ~+75 to +80 mV, and low probability of opening (P o) at +20 mV that increased ~10-fold at +40 mV and ~60-fold at +60 mV. Using the inside-out configuration at +30 mV, reduction of intracellular [Ca(2+)] from ~300 nM to Ca(2+)-free decreased the P o by ~85 %, whereas elevation to ~800 nM increased P o by ~50-fold. The BK channel activator NS1619 (10 μM) enhanced the P o by ~10-fold at +30 mV; subsequent application of the selective BK channel inhibitor paxilline (500 nM) blocked the activity. Changes in intracellular [Ca(2+)] or the addition of NS1619 did not significantly alter the current amplitude or single-channel conductance. This is the first report to provide biophysical and pharmacological profiles of native human DSM single BK channels highlighting their importance in regulating human DSM excitability.

  3. Range resolved mode mixing in a large volume for the mitigation of speckle and strategic target orientation requirements in active millimeter-wave imaging.

    PubMed

    Patrick, Mark A; Holt, Jennifer A; Joye, Colin D; De Lucia, Frank C

    2015-04-01

    In spite of many reports of active millimeter-wave imaging in the literature, speckle and requirements for cooperative target orientation significantly reduce its practical usefulness. Here we report a new technique, range resolved mode mixing (RRMM), which significantly mitigates both of these issues. It also provides a three-dimensional (3D) image. RRMM accomplishes this by combining multimode illumination (which eliminates the requirement for cooperative target orientation) with range resolution (which provides statistical independence of speckle patterns for averaging and the 3D image). The use of a 5W extended interaction klystron amplifier results in large signal margins in the 50 m scale atrium of the Physics Department at Ohio State University. It appears that there are a number of scenarios out to a range of 1 km for which this approach is useful to provide 3D images, with minimal speckle, and no requirement for cooperative target orientation.

  4. Magnetic-activated cell sorting (MACS) can be used as a large-scale method for establishing zebrafish neuronal cell cultures

    PubMed Central

    Welzel, Georg; Seitz, Daniel; Schuster, Stefan

    2015-01-01

    Neuronal cell cultures offer a crucial tool to mechanistically analyse regeneration in the nervous system. Despite the increasing importance of zebrafish (Danio rerio) as an in vivo model in neurobiological and biomedical research, in vitro approaches to the nervous system are lagging far behind and no method is currently available for establishing enriched neuronal cell cultures. Here we show that magnetic-activated cell sorting (MACS) can be used for the large-scale generation of neuronal-restricted progenitor (NRP) cultures from embryonic zebrafish. Our findings provide a simple and semi-automated method that is likely to boost the use of neuronal cell cultures as a tool for the mechanistic dissection of key processes in neuronal regeneration and development. PMID:25609542

  5. Sensitive detection of beryllium using a fiber optic liquid waveguide cell.

    PubMed

    Deng, Gang; Wei, Lily; Collins, Greg E

    2003-05-28

    The metallochromic chelating agent, Chromazurol S, has been utilized in conjunction with a fiber optic liquid waveguide capillary cell to enable the sensitive detection of beryllium in solution (30 ng l(-1) detection limit) and following extraction from a contaminated plexiglas surface (0.5 ng cm(-2) detection limit). The addition of a cationic surfactant, cetylpyridinium chloride, to Chromazurol S at pH 10 in Tris-HCl buffer results in the formation of two bathochromic peaks in the visible spectrum following metal chelation by beryllium. The first absorbance band, at 515 nm, is intermediate in nature, permitting maximal sensitivity for low beryllium concentrations, but diminishing in intensity at concentrations above 100 mug l(-1). The second absorbance band, centered at 610 nm, dominates for beryllium concentrations of 100 mug l(-1) and above. Experimental conditions including pH, buffer type, additive surfactants, masking agents, and dye concentration were investigated in order to optimize detection sensitivity and selectivity. A fiber optic spectrometer is used with both a liquid waveguide capillary cell and 1 cm cuvette cell, to give a sensitive and broad dynamic range for beryllium detection that capitalizes on both beryllium metal chelate absorbance bands formed under these conditions.

  6. Error analysis and measurement uncertainty for a fiber grating strain-temperature sensor.

    PubMed

    Tang, Jaw-Luen; Wang, Jian-Neng

    2010-01-01

    A fiber grating sensor capable of distinguishing between temperature and strain, using a reference and a dual-wavelength fiber Bragg grating, is presented. Error analysis and measurement uncertainty for this sensor are studied theoretically and experimentally. The measured root mean squared errors for temperature T and strain ε were estimated to be 0.13 °C and 6 με, respectively. The maximum errors for temperature and strain were calculated as 0.00155 T + 2.90 × 10(-6) ε and 3.59 × 10(-5) ε + 0.01887 T, respectively. Using the estimation of expanded uncertainty at 95% confidence level with a coverage factor of k = 2.205, temperature and strain measurement uncertainties were evaluated as 2.60 °C and 32.05 με, respectively. For the first time, to our knowledge, we have demonstrated the feasibility of estimating the measurement uncertainty for simultaneous strain-temperature sensing with such a fiber grating sensor.

  7. Large-scale distribution and activity of prokaryotes in deep-sea surface sediments of the Mediterranean Sea and the adjacent Atlantic Ocean.

    PubMed

    Giovannelli, Donato; Molari, Massimiliano; d'Errico, Giuseppe; Baldrighi, Elisa; Pala, Claudia; Manini, Elena

    2013-01-01

    The deep-sea represents a substantial portion of the biosphere and has a major influence on carbon cycling and global biogeochemistry. Benthic deep-sea prokaryotes have crucial roles in this ecosystem, with their recycling of organic matter from the photic zone. Despite this, little is known about the large-scale distribution of prokaryotes in the surface deep-sea sediments. To assess the influence of environmental and trophic variables on the large-scale distribution of prokaryotes, we investigated the prokaryotic assemblage composition (Bacteria to Archaea and Euryarchaeota to Crenarchaeota ratio) and activity in the surface deep-sea sediments of the Mediterranean Sea and the adjacent North Atlantic Ocean. Prokaryotic abundance and biomass did not vary significantly across the Mediterranean Sea; however, there were depth-related trends in all areas. The abundance of prokaryotes was positively correlated with the sedimentary concentration of protein, an indicator of the quality and bioavailability of organic matter. Moving eastwards, the Bacteria contribution to the total prokaryotes decreased, which appears to be linked to the more oligotrophic conditions of the Eastern Mediterranean basins. Despite the increased importance of Archaea, the contributions of Crenarchaeota Marine Group I to the total pool was relatively constant across the investigated stations, with the exception of Matapan-Vavilov Deep, in which Euryarchaeota Marine Group II dominated. Overall, our data suggest that deeper areas of the Mediterranean Sea share more similar communities with each other than with shallower sites. Freshness and quality of sedimentary organic matter were identified through Generalized Additive Model analysis as the major factors for describing the variation in the prokaryotic community structure and activity in the surface deep-sea sediments. Longitude was also important in explaining the observed variability, which suggests that the overlying water masses might have a

  8. Long duration (>4 Ma) and steady-state volcanic activity in the early Cretaceous Paraná-Etendeka Large Igneous Province: New palaeomagnetic data from Namibia

    NASA Astrophysics Data System (ADS)

    Dodd, Sarah C.; Mac Niocaill, Conall; Muxworthy, Adrian R.

    2015-03-01

    There is long-standing correlation between Large Igneous Provinces (LIPs) and major mass extinction events in the Geological Record, postulated to be due to the emission of large quantities of volcanic gases over a geologically short period of time causing major climatic perturbations within the Earth system. The ∼135 Ma Paraná-Etendeka volcanic province of Brazil and Namibia represents something of an enigma amongst LIPs. Despite an erupted volume (>1 Mkm3) comparable to other LIPs associated with mass extinctions, such as the Siberian or Deccan traps, it is not linked to a known mass extinction event. This suggests that the Paraná-Etendeka volcanic province was emplaced over longer timescales than other LIPs, and/or emitted a lower concentration of volatiles, directly or indirectly during its emplacement. We present a new, detailed magnetostratigraphy for the Etendeka portion of the province that suggests emplacement took place over longer timescales (>4 Ma) than those associated with other LIPs. Palaeomagnetic analysis of 893 specimens from 99 sites, in sections that encompass nearly the complete Etendeka stratigraphy, yielded high-quality data from 70 sites (612 specimens). These record 16 individual polarity intervals, which can be correlated with Chrons 15 to 11 of the geomagnetic polarity time scale (GPTS) while also providing two new, high quality palaeopoles for South Africa at 130-135 Ma. Our magnetostratigraphy reveals a minimum period of volcanic activity in excess of 4 Myrs and, importantly, we find no evidence for major changes in the rates of volcanic activity through that time period, in contrast to other LIPs where volcanism seems to be concentrated in major pulses. This suggests that the anomalously feeble environmental impact of Paraná-Etendeka volcanism may be due to lower effusion rates reducing the atmospheric loading due to volcanogenic volatiles.

  9. Large-Scale Distribution and Activity of Prokaryotes in Deep-Sea Surface Sediments of the Mediterranean Sea and the Adjacent Atlantic Ocean

    PubMed Central

    Giovannelli, Donato; Molari, Massimiliano; d’Errico, Giuseppe; Baldrighi, Elisa; Pala, Claudia; Manini, Elena

    2013-01-01

    The deep-sea represents a substantial portion of the biosphere and has a major influence on carbon cycling and global biogeochemistry. Benthic deep-sea prokaryotes have crucial roles in this ecosystem, with their recycling of organic matter from the photic zone. Despite this, little is known about the large-scale distribution of prokaryotes in the surface deep-sea sediments. To assess the influence of environmental and trophic variables on the large-scale distribution of prokaryotes, we investigated the prokaryotic assemblage composition (Bacteria to Archaea and Euryarchaeota to Crenarchaeota ratio) and activity in the surface deep-sea sediments of the Mediterranean Sea and the adjacent North Atlantic Ocean. Prokaryotic abundance and biomass did not vary significantly across the Mediterranean Sea; however, there were depth-related trends in all areas. The abundance of prokaryotes was positively correlated with the sedimentary concentration of protein, an indicator of the quality and bioavailability of organic matter. Moving eastwards, the Bacteria contribution to the total prokaryotes decreased, which appears to be linked to the more oligotrophic conditions of the Eastern Mediterranean basins. Despite the increased importance of Archaea, the contributions of Crenarchaeota Marine Group I to the total pool was relatively constant across the investigated stations, with the exception of Matapan-Vavilov Deep, in which Euryarchaeota Marine Group II dominated. Overall, our data suggest that deeper areas of the Mediterranean Sea share more similar communities with each other than with shallower sites. Freshness and quality of sedimentary organic matter were identified through Generalized Additive Model analysis as the major factors for describing the variation in the prokaryotic community structure and activity in the surface deep-sea sediments. Longitude was also important in explaining the observed variability, which suggests that the overlying water masses might have a

  10. Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by 36Cl dating. Insight on an Alpine-scale landslide activity

    NASA Astrophysics Data System (ADS)

    Zerathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier

    2014-04-01

    Although it is generally assumed that the internal structure of a slope (e.g. lithology and rock mass properties, inherited faults and heterogeneities, etc.) is preponderant for the progressive development of large-scale landslides, the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing, seismic activities or climatic changes, especially when considering landslide cluster at an orogen-scale, is still debated. Highlighting in this study the spatial and temporal concordant clustering of deep-seated slope failures in the external Southwestern Alps, we discuss and review the possible causes for such wide-spread slope instabilities at both local and larger (Alpine) scale. High resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the Southwestern Alps, determining their structural model, precising their depth limit (100-200 m) as well as the involved rock volumes (>107 m3). We show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block-spread model of deformation that could evolve in rock-collapse events. Cosmic ray exposure dating (CRE), using both 36Cl and 10Be in coexisting limestone and chert, respectively, has been carried out from the main scarps of six Deep Seated Landslides (DSL) and leads to landslide-failure CRE ages ranging from 3.7 to 4.7 ka. They highlighted: (i) mainly single and fast ruptures and (ii) a possible concomitant initiation with a main peak of activity between 3.3 and 5.1 ka, centered at ca 4.2 ka. Because this region was not affected by historical glaciations events, landslide triggering by glacial unloading can be excluded. The presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium. In effect, the

  11. Comparative study of emerging micropollutants removal by aerobic activated sludge of large laboratory-scale membrane bioreactors and sequencing batch reactors under low-temperature conditions.

    PubMed

    Kruglova, Antonina; Kråkström, Matilda; Riska, Mats; Mikola, Anna; Rantanen, Pirjo; Vahala, Riku; Kronberg, Leif

    2016-08-01

    Four emerging micropollutants ibuprofen, diclofenac, estrone (E1) and 17α-ethinylestradiol (EE2) were studied in large laboratory-scale wastewater treatment plants (WWTPs) with high nitrifying activity. Activated sludge (AS) with sludge retention times (SRTs) of 12days and 14days in sequencing batch reactors (SBRs) and 30days, 60days and 90days in membrane bioreactors (MBRs) were examined at 8°C and 12°C. Concentrations of pharmaceuticals and their main metabolites were analysed in liquid phase and solid phase of AS by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A remarkable amount of contaminants were detected in solids of AS, meaning the accumulation of micropollutants in bacterial cells. The biodegradation rate constants (Kbiol) were affected by SRT and temperature. MBR with a 90-day SRT showed the best results of removal. Conventional SBR process was inefficient at 8°C showing Kbiol values lower than 0.5lgSS(-1)d(-1) for studied micropollutants. PMID:27128192

  12. Comparative study of emerging micropollutants removal by aerobic activated sludge of large laboratory-scale membrane bioreactors and sequencing batch reactors under low-temperature conditions.

    PubMed

    Kruglova, Antonina; Kråkström, Matilda; Riska, Mats; Mikola, Anna; Rantanen, Pirjo; Vahala, Riku; Kronberg, Leif

    2016-08-01

    Four emerging micropollutants ibuprofen, diclofenac, estrone (E1) and 17α-ethinylestradiol (EE2) were studied in large laboratory-scale wastewater treatment plants (WWTPs) with high nitrifying activity. Activated sludge (AS) with sludge retention times (SRTs) of 12days and 14days in sequencing batch reactors (SBRs) and 30days, 60days and 90days in membrane bioreactors (MBRs) were examined at 8°C and 12°C. Concentrations of pharmaceuticals and their main metabolites were analysed in liquid phase and solid phase of AS by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A remarkable amount of contaminants were detected in solids of AS, meaning the accumulation of micropollutants in bacterial cells. The biodegradation rate constants (Kbiol) were affected by SRT and temperature. MBR with a 90-day SRT showed the best results of removal. Conventional SBR process was inefficient at 8°C showing Kbiol values lower than 0.5lgSS(-1)d(-1) for studied micropollutants.

  13. A Screen for Modulators of Large T Antigen's ATPase Activity Uncovers Novel Inhibitors of Simian Virus 40 and BK Virus Replication

    PubMed Central

    Seguin, Sandlin P.; Ireland, Alex W.; Gupta, Tushar; Wright, Christine M.; Miyata, Yoshinari; Wipf, Peter; Pipas, James M.; Gestwicki, Jason E.; Brodsky, Jeffrey L.

    2012-01-01

    New polyomaviruses are continually being identified, and it is likely that links between this virus family and disease will continue to emerge. Unfortunately, a specific treatment for polyomavirus-associated disease is lacking. Because polyomaviruses express large Tumor Antigen, TAg, we hypothesized that small molecule inhibitors of the essential ATPase activity of TAg would inhibit viral replication. Using a new screening platform, we identified inhibitors of TAg's ATPase activity. Lead compounds were moved into a secondary assay, and ultimately two FDA approved compounds, bithionol and hexachlorophene, were identified as the most potent TAg inhibitors known to date. Both compounds inhibited Simian Virus 40 replication as assessed by plaque assay and quantitative PCR. Moreover, these compounds inhibited BK virus, which causes BKV Associated Nephropathy. In neither case was host cell viability compromised at these concentrations. Our data indicate that directed screening for TAg inhibitors is a viable method to identify polyomavirus inhibitors, and that bithionol and hexachlorophene represent lead compounds that may be further modified and/or ultimately used to combat diseases associated with polyomavirus infection. PMID:22898086

  14. Cerdulatinib, a novel dual SYK/JAK kinase inhibitor, has broad anti-tumor activity in both ABC and GCB types of diffuse large B cell lymphoma

    PubMed Central

    Ma, Jiao; Xing, Wei; Coffey, Greg; Dresser, Karen; Lu, Kellie; Guo, Ailin; Raca, Gordana; Pandey, Anjali; Conley, Pamela; Yu, Hongbo; Wang, Y. Lynn

    2015-01-01

    B-cell receptor (BCR) and JAK/STAT pathways play critical roles in diffuse large B-cell lymphoma (DLBCL). Herein, we investigated the anti-lymphoma activity of cerdulatinib, a novel compound that dually targets SYK and JAK/STAT pathways. On a tissue microarray of 62 primary DLBCL tumors, 58% expressed either phosphorylated SYK or STAT3 or both. SYK and STAT3 are also phosphorylated in a panel of eleven DLBCL cell lines although ABC and GCB subtypes exhibited different JAK/STAT and BCR signaling profiles. In both ABC and GCB cell lines, cerdulatinib induced apoptosis that was associated with caspase-3 and PARP cleavage. The compound also blocked G1/S transition and caused cell cycle arrest, accompanied by inhibition of RB phosphorylation and down-regulation of cyclin E. Phosphorylation of BCR components and STAT3 was sensitive to cerdulatinib in both ABC and GCB cell lines under stimulated conditions. Importantly, JAK/STAT and BCR signaling can be blocked by cerdulatinib in primary GCB and non-GCB DLBCL tumor cells that were accompanied by cell death. Our work provides mechanistic insights into the actions of cerdulatinib, suggesting that the drug has a broad anti-tumor activity in both ABC and GCB DLBCL, at least in part by inhibiting SYK and JAK pathways. PMID:26575169

  15. High-throughput combinatorial screening identifies drugs that cooperate with ibrutinib to kill activated B-cell–like diffuse large B-cell lymphoma cells

    PubMed Central

    Mathews Griner, Lesley A.; Guha, Rajarshi; Shinn, Paul; Young, Ryan M.; Keller, Jonathan M.; Liu, Dongbo; Goldlust, Ian S.; Yasgar, Adam; McKnight, Crystal; Boxer, Matthew B.; Duveau, Damien Y.; Jiang, Jian-Kang; Michael, Sam; Mierzwa, Tim; Huang, Wenwei; Walsh, Martin J.; Mott, Bryan T.; Patel, Paresma; Leister, William; Maloney, David J.; Leclair, Christopher A.; Rai, Ganesha; Jadhav, Ajit; Peyser, Brian D.; Austin, Christopher P.; Martin, Scott E.; Simeonov, Anton; Ferrer, Marc; Staudt, Louis M.; Thomas, Craig J.

    2014-01-01

    The clinical development of drug combinations is typically achieved through trial-and-error or via insight gained through a detailed molecular understanding of dysregulated signaling pathways in a specific cancer type. Unbiased small-molecule combination (matrix) screening represents a high-throughput means to explore hundreds and even thousands of drug–drug pairs for potential investigation and translation. Here, we describe a high-throughput screening platform capable of testing compounds in pairwise matrix blocks for the rapid and systematic identification of synergistic, additive, and antagonistic drug combinations. We use this platform to define potential therapeutic combinations for the activated B-cell–like subtype (ABC) of diffuse large B-cell lymphoma (DLBCL). We identify drugs with synergy, additivity, and antagonism with the Bruton’s tyrosine kinase inhibitor ibrutinib, which targets the chronic active B-cell receptor signaling that characterizes ABC DLBCL. Ibrutinib interacted favorably with a wide range of compounds, including inhibitors of the PI3K-AKT-mammalian target of rapamycin signaling cascade, other B-cell receptor pathway inhibitors, Bcl-2 family inhibitors, and several components of chemotherapy that is the standard of care for DLBCL. PMID:24469833

  16. Variety in emotional life: within-category typicality of emotional experiences is associated with neural activity in large-scale brain networks.

    PubMed

    Wilson-Mendenhall, Christine D; Barrett, Lisa Feldman; Barsalou, Lawrence W

    2015-01-01

    The tremendous variability within categories of human emotional experience receives little empirical attention. We hypothesized that atypical instances of emotion categories (e.g. pleasant fear of thrill-seeking) would be processed less efficiently than typical instances of emotion categories (e.g. unpleasant fear of violent threat) in large-scale brain networks. During a novel fMRI paradigm, participants immersed themselves in scenarios designed to induce atypical and typical experiences of fear, sadness or happiness (scenario immersion), and then focused on and rated the pleasant or unpleasant feeling that emerged (valence focus) in most trials. As predicted, reliably greater activity in the 'default mode' network (including medial prefrontal cortex and posterior cingulate) was observed for atypical (vs typical) emotional experiences during scenario immersion, suggesting atypical instances require greater conceptual processing to situate the socio-emotional experience. During valence focus, reliably greater activity was observed for atypical (vs typical) emotional experiences in the 'salience' network (including anterior insula and anterior cingulate), suggesting atypical instances place greater demands on integrating shifting body signals with the sensory and social context. Consistent with emerging psychological construction approaches to emotion, these findings demonstrate that is it important to study the variability within common categories of emotional experience.

  17. Modified rubisco large subunit n-methyltransferase useful for targeting molecules to the active-site vicinity of ribulose-1,5-bisphosphate

    DOEpatents

    Houtz, Robert L.

    2012-03-20

    The present invention generally relates to a modified Rubisco large subunit .sup..epsilon.N-Methyltransferase (Rubisco LSMT, or RLSMT). The present invention also relates to a modified RLSMT-carbonic anhydrase (RLSMT-CA). This modified RLSMT-CA improves the efficiency of the reduction of CO.sub.2 during photosynthesis, which may increase plant growth rates. The present invention also relates to nucleic acids encoding the modified RLSMT-CA or modified RLSMT. Also, the present invention relates to cells including the modified RLSMT-CA or modified RLSMT, plants containing the modified RLSMT-CA or modified RLSMT, and methods using compositions of the present invention. In addition, the present invention relates to antibodies conjugated to CA which may bind to Rubisco, and antibodies which bind a modified RLSMT-CA. The invention also relates to modified forms of the LS and SS of Rubisco where the modified forms are fusions with CA or biologically active fragments thereof. The present invention provides methods of altering Rubisco carboxylase activity and altering plant growth.

  18. Closed Large Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Large Cell Clouds in the South Pacific     ... unperturbed by cyclonic or frontal activity. When the cell centers are cloudy and the main sinking motion is concentrated at cell ...

  19. Beta-adrenergic relaxation of mouse urinary bladder smooth muscle in the absence of large-conductance Ca2+-activated K+ channel.

    PubMed

    Brown, Sean M; Bentcheva-Petkova, Lilia M; Liu, Lei; Hristov, Kiril L; Chen, Muyan; Kellett, Whitney F; Meredith, Andrea L; Aldrich, Richard W; Nelson, Mark T; Petkov, Georgi V

    2008-10-01

    In urinary bladder smooth muscle (UBSM), stimulation of beta-adrenergic receptors (beta-ARs) leads to activation of the large-conductance Ca2+-activated K+ (BK) channel currents (Petkov GV and Nelson MT. Am J Physiol Cell Physiol 288: C1255-C1263, 2005). In this study we tested the hypothesis that the BK channel mediates UBSM relaxation in response to beta-AR stimulation using the highly specific BK channel inhibitor iberiotoxin (IBTX) and a BK channel knockout (BK-KO) mouse model in which the gene for the pore-forming subunit was deleted. UBSM strips isolated from wild-type (WT) and BK-KO mice were stimulated with 20 mM K+ or 1 microM carbachol to induce phasic and tonic contractions. BK-KO and WT UBSM strips pretreated with IBTX had increased overall contractility, and UBSM BK-KO cells were depolarized with approximately 12 mV. Isoproterenol, a nonspecific beta-AR agonist, and forskolin, an adenylate cyclase activator, decreased phasic and tonic contractions of WT UBSM strips in a concentration-dependent manner. In the presence of IBTX, the concentration-response curves to isoproterenol and forskolin were shifted to the right in WT UBSM strips. Isoproterenol- and forskolin-mediated relaxations were enhanced in BK-KO UBSM strips, and a leftward shift in the concentration-response curves was observed. The leftward shift was eliminated upon PKA inhibition with H-89, suggesting upregulation of the beta-AR-cAMP pathway in BK-KO mice. These results indicate that the BK channel is a key modulator in beta-AR-mediated relaxation of UBSM and further suggest that alterations in BK channel expression or function could contribute to some pathophysiological conditions such as overactive bladder and urinary incontinence.

  20. Hyperimmune Bovine Colostrum as a Low-Cost, Large-Scale Source of Antibodies with Broad Neutralizing Activity for HIV-1 Envelope with Potential Use in Microbicides

    PubMed Central

    Kramski, Marit; Center, Rob J.; Wheatley, Adam K.; Jacobson, Jonathan C.; Alexander, Marina R.; Rawlin, Grant

    2012-01-01

    Bovine colostrum (first milk) contains very high concentrations of IgG, and on average 1 kg (500 g/liter) of IgG can be harvested from each immunized cow immediately after calving. We used a modified vaccination strategy together with established production systems from the dairy food industry for the large-scale manufacture of broadly neutralizing HIV-1 IgG. This approach provides a low-cost mucosal HIV preventive agent potentially suitable for a topical microbicide. Four cows were vaccinated pre- and/or postconception with recombinant HIV-1 gp140 envelope (Env) oligomers of clade B or A, B, and C. Colostrum and purified colostrum IgG were assessed for cross-clade binding and neutralization against a panel of 27 Env-pseudotyped reporter viruses. Vaccination elicited high anti-gp140 IgG titers in serum and colostrum with reciprocal endpoint titers of up to 1 × 105. While nonimmune colostrum showed some intrinsic neutralizing activity, colostrum from 2 cows receiving a longer-duration vaccination regimen demonstrated broad HIV-1-neutralizing activity. Colostrum-purified polyclonal IgG retained gp140 reactivity and neutralization activity and blocked the binding of the b12 monoclonal antibody to gp140, showing specificity for the CD4 binding site. Colostrum-derived anti-HIV antibodies offer a cost-effective option for preparing the substantial quantities of broadly neutralizing antibodies that would be needed in a low-cost topical combination HIV-1 microbicide. PMID:22664963

  1. Hyperimmune bovine colostrum as a low-cost, large-scale source of antibodies with broad neutralizing activity for HIV-1 envelope with potential use in microbicides.

    PubMed

    Kramski, Marit; Center, Rob J; Wheatley, Adam K; Jacobson, Jonathan C; Alexander, Marina R; Rawlin, Grant; Purcell, Damian F J

    2012-08-01

    Bovine colostrum (first milk) contains very high concentrations of IgG, and on average 1 kg (500 g/liter) of IgG can be harvested from each immunized cow immediately after calving. We used a modified vaccination strategy together with established production systems from the dairy food industry for the large-scale manufacture of broadly neutralizing HIV-1 IgG. This approach provides a low-cost mucosal HIV preventive agent potentially suitable for a topical microbicide. Four cows were vaccinated pre- and/or postconception with recombinant HIV-1 gp140 envelope (Env) oligomers of clade B or A, B, and C. Colostrum and purified colostrum IgG were assessed for cross-clade binding and neutralization against a panel of 27 Env-pseudotyped reporter viruses. Vaccination elicited high anti-gp140 IgG titers in serum and colostrum with reciprocal endpoint titers of up to 1 × 10(5). While nonimmune colostrum showed some intrinsic neutralizing activity, colostrum from 2 cows receiving a longer-duration vaccination regimen demonstrated broad HIV-1-neutralizing activity. Colostrum-purified polyclonal IgG retained gp140 reactivity and neutralization activity and blocked the binding of the b12 monoclonal antibody to gp140, showing specificity for the CD4 binding site. Colostrum-derived anti-HIV antibodies offer a cost-effective option for preparing the substantial quantities of broadly neutralizing antibodies that would be needed in a low-cost topical combination HIV-1 microbicide. PMID:22664963

  2. Evaluation of the effects of ice massage applied to large intestine 4 (hegu) on postpartum pain during the active phase of labor

    PubMed Central

    Can, Hafize Ozturk; Saruhan, Aynur

    2015-01-01

    Background: The uterus continues to contract after childbirth. The pain caused by the contractions of the uterus can be as severe as labor pain. The study was aimed to evaluate the effects of ice massage applied to the large intestine 4 (LI4) on postpartum pain during the active phase of labor. Materials and Methods: The study was designed as a randomized controlled trial with three groups and carried out in two stages. The study sample comprised of 150 pregnant women, who were referred to a maternity hospital. In the experimental group, ice massage was applied to LI4 during four contractions within the active phase of labor. In the placebo group, pressure was applied to LI4 using silicone balloons and the third group was the control group. The Visual Analog Scale (VAS) and The McGill (Melzack) Pain Questionnaire (MPQ) were compared among the experimental, placebo, and control groups. Results: The mothers in the ice application group had the lowest mean VAS score. It was determined that ice massage applied to LI4 during the active phase of labor did not lead to any statistical differences in mothers in the first 24 hours postpartum in terms of the characteristics of the pain with MPQ and VAS. Conclusions: In the study, the perception of pain was tried to be minimized by applying pressure with ice balloons to LI4. However, although the application was determined to have made no difference in the pain intensity, the mothers’ statements in the ice application group suggested that they felt more comfortable than did the mothers in the other groups. PMID:25709702

  3. Cholinergic modulation of large-conductance calcium-activated potassium channels regulates synaptic strength and spine calcium in cartwheel cells of the dorsal cochlear nucleus.

    PubMed

    He, Shan; Wang, Ya-Xian; Petralia, Ronald S; Brenowitz, Stephan D

    2014-04-01

    Acetylcholine is a neuromodulatory transmitter that controls synaptic plasticity and sensory processing in many brain regions. The dorsal cochlear nucleus (DCN) is an auditory brainstem nucleus that integrates auditory signals from the cochlea with multisensory inputs from several brainstem nuclei and receives prominent cholinergic projections. In the auditory periphery, cholinergic modulation serves a neuroprotective function, reducing cochlear output under high sound levels. However, the role of cholinergic signaling in the DCN is less understood. Here we examine postsynaptic mechanisms of cholinergic modulation at glutamatergic synapses formed by parallel fiber axons onto cartwheel cells (CWCs) in the apical DCN circuit from mouse brainstem slice using calcium (Ca) imaging combined with two-photon laser glutamate uncaging onto CWC spines. Activation of muscarinic acetylcholine receptors (mAChRs) significantly increased the amplitude of both uncaging-evoked EPSPs (uEPSPs) and spine Ca transients. Our results demonstrate that mAChRs in CWC spines act by suppressing large-conductance calcium-activated potassium (BK) channels, and this effect is mediated through the cAMP/protein kinase A signaling pathway. Blocking BK channels relieves voltage-dependent magnesium block of NMDA receptors, thereby enhancing uEPSPs and spine Ca transients. Finally, we demonstrate that mAChR activation inhibits L-type Ca channels and thus may contribute to the suppression of BK channels by mAChRs. In summary, we demonstrate a novel role for BK channels in regulating glutamatergic transmission and show that this mechanism is under modulatory control of mAChRs.

  4. Cholinergic Modulation of Large-Conductance Calcium-Activated Potassium Channels Regulates Synaptic Strength and Spine Calcium in Cartwheel Cells of the Dorsal Cochlear Nucleus

    PubMed Central

    He, Shan; Wang, Ya-Xian; Petralia, Ronald S.

    2014-01-01

    Acetylcholine is a neuromodulatory transmitter that controls synaptic plasticity and sensory processing in many brain regions. The dorsal cochlear nucleus (DCN) is an auditory brainstem nucleus that integrates auditory signals from the cochlea with multisensory inputs from several brainstem nuclei and receives prominent cholinergic projections. In the auditory periphery, cholinergic modulation serves a neuroprotective function, reducing cochlear output under high sound levels. However, the role of cholinergic signaling in the DCN is less understood. Here we examine postsynaptic mechanisms of cholinergic modulation at glutamatergic synapses formed by parallel fiber axons onto cartwheel cells (CWCs) in the apical DCN circuit from mouse brainstem slice using calcium (Ca) imaging combined with two-photon laser glutamate uncaging onto CWC spines. Activation of muscarinic acetylcholine receptors (mAChRs) significantly increased the amplitude of both uncaging-evoked EPSPs (uEPSPs) and spine Ca transients. Our results demonstrate that mAChRs in CWC spines act by suppressing large-conductance calcium-activated potassium (BK) channels, and this effect is mediated through the cAMP/protein kinase A signaling pathway. Blocking BK channels relieves voltage-dependent magnesium block of NMDA receptors, thereby enhancing uEPSPs and spine Ca transients. Finally, we demonstrate that mAChR activation inhibits L-type Ca channels and thus may contribute to the suppression of BK channels by mAChRs. In summary, we demonstrate a novel role for BK channels in regulating glutamatergic transmission and show that this mechanism is under modulatory control of mAChRs. PMID:24719104

  5. Simian virus 40 large T antigen contains two independent activities that cooperate with a ras oncogene to transform rat embryo fibroblasts.

    PubMed Central

    Cavender, J F; Conn, A; Epler, M; Lacko, H; Tevethia, M J

    1995-01-01

    The simian virus 40 large T antigen immortalizes growing primary cells in culture. In addition, this viral oncoprotein cooperates with an activated ras protein to produce dense foci on monolayers of rat embryo fibroblasts (REF). The relationship between independent immortalization and cooperative transformation with ras has not been defined. Previously, two regions of T antigen were shown to contain immortalization activities. An N-terminal fragment consisting of amino acids 1 to 147 immortalizes rodent cells (L. Sompayrac and K. J. Danna, Virology 181:412-415, 1991). Loss-of-function analysis indicated that immortalization depended on integrity of the T-antigen segments containing amino acids 351 to 450 and 533 to 626 (T. D. Kierstead and M. J. Tevethia, J. Virol. 67:1817-1829, 1993). The experiments described here were directed toward determining whether these same T-antigen regions were sufficient for cooperation with ras. Initially, constructs that produce T antigens containing amino acids 176 to 708 (T176-708) or 1 to 147 were tested in a ras cooperation assay. Both polypeptides cooperated with ras to produce dense foci on monolayers of primary REF. These results showed that T antigen contains two separate ras cooperation activities. In order to determine the N-terminal limit of the ras cooperation activity contained within the T176-708 polypeptide, a series of constructs designed to produce fusion proteins containing T-antigen segments beginning at residues 251, 301, 337, 351, 371, 401, 451, 501, 551, 601, and 651 was generated. Each of these constructs was tested for the capacity to cooperate with ras to produce dense foci on REF monolayers. The results indicated that a polypeptide containing T-antigen amino acids 251 to 708 (T251-708) was sufficient to cooperate with ras, whereas the more extensively truncated products were not. The abilities of the N-terminally truncated T antigens to bind p53 were examined in p53-deficient cells infected with a

  6. Large wind turbine generators

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Donovon, R. M.

    1978-01-01

    The development associated with large wind turbine systems is briefly described. The scope of this activity includes the development of several large wind turbines ranging in size from 100 kW to several megawatt levels. A description of the wind turbine systems, their programmatic status and a summary of their potential costs is included.

  7. Using a Learning Activity Sequence in Large-Enrollment Physical Geology Classes: Supporting the Needs of Underserved Students While Motivating Interest, Learning, and Success

    NASA Astrophysics Data System (ADS)

    Pun, A.; Smith, G. A.

    2011-12-01

    The learning activity sequence (LAS) strategy is a student-focused pedagogy that emphasizes active classroom learning to promote learning among all students, and in particular, those with diverse backgrounds. Online assessments both set the stage for active learning and help students synthesize material during their learning. UNM is one of only two Carnegie Research University Very High institutions also designated as Hispanic-serving and the only state flagship university that is also a majority-minority undergraduate institution. In 2010 Hispanics comprised 40% of 20,655 undergraduates (and 49% of freshmen), 37% of undergraduates were Pell Grant recipients (the largest proportion of any public flagship research university; J. Blacks Higher Ed., 2009) and 44% of incoming freshmen were first-generation students. To maximize student learning in this environment rich in traditionally underserved students, we designed a LAS for nonmajor physical geology (enrollments 100-160) that integrates in-class instruction with structured out-of-class learning. The LAS has 3 essential parts: Students read before class to acquire knowledge used during in-class collaborative, active-learning activities that build conceptual understanding. Lastly, students review notes and synthesize what they've learned before moving on to the next topic. The model combines online and in-class learning and assessment: Online reading assessments before class; active-learning experiences during class; online learning assessments after class. Class sessions include short lectures, peer instruction "clickers", and small-group problem solving (lecture tutorials). Undergraduate Peer-Learning Facilitators are available during class time to help students with problem solving. Effectiveness of the LAS approach is reflected in three types of measurements. (1) Using the LAS strategy, the overall rate of students earning a grade of C or higher is higher than compared to the average for all large

  8. Nitric oxide (NO)-induced activation of large conductance Ca2+-dependent K+ channels (BKCa) in smooth muscle cells isolated from the rat mesenteric artery

    PubMed Central

    Mistry, D K; Garland, C J

    1998-01-01

    To assess the action of nitric oxide (NO) and NO-donors on K+ current evoked either by voltage ramps or steps, patch clamp recordings were made from smooth muscle cells freshly isolated from secondary and tertiary branches of the rat mesenteric artery. Inside-out patches contained channels, the open probability of which increased with [Ca2+]i. The channels had a linear slope conductance of 212±5 pS (n=12) in symmetrical (140 mM) K+ solutions which reversed in direction at 4.4 mV. In addition, the channels showed K+ selectivity, in that the reversal potential shifted in a manner similar to that predicted by the Nernst potential for K+. Barium (1 mM) applied to the intracellular face of the channel produced a voltage-dependent block and external tetraethylammonium (TEA; at 1 mM) caused a large reduction in the unitary current amplitude. Taken together, these observations indicate that the channel most closely resembled BKCa. In five out of six inside-out patches, NO (45 or 67 μM) produced an increase in BKCa activity. In inside-out patches, BKCa activity was also enhanced in some patches with 100 or 200 μM 3-morpholino-sydnonimine (SIN-1) (4/11) and 100 μM sodium nitroprusside (SNP) (3/8). The variability in channel opening with the NO donors may reflect variability in the release of NO from these compounds. In inside-out patches, 100 μM SIN-1 failed to increase BKCa activity (in all 4 patches tested), while at a higher (500 μM) concentration SIN-1 had a direct blocking effect on the channels (n=3). NO applied directly to inside-out patches increased (P<0.05) BKCa activity in two patches. In the majority of cells (6 out of 7), application of NO (45 or 67 μM) evoked an increase in the amplitude of whole-cell currents in perforated patches. This action was not affected by the soluble guanylyl cyclase inhibitor, 1H-[1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ). An increase in whole-cell current was also evoked with either of the NO donors

  9. Occurrence of anomalous seismic activity preceding large to great earthquakes in northeast India region with special reference to 6 August 1988

    NASA Astrophysics Data System (ADS)

    Singh, H. N.; Shanker, D.; Singh, V. P.

    2005-02-01

    Seismicity database from 1860 to 1985 of northeast India region bounded by the area 20°-32°N and 82°-100°E have been analyzed for the identification of precursory swarm/anomalous seismic activity preceding large to great earthquakes with M ≥ 7.5. It is observed that with the exception of three earthquakes (1908, 1912 and 1918), the large earthquakes of 1897, 1946, 1947, 1950 and 1951/1952 were preceded by well-developed epoch of swarm/anomalous seismic activity in space and time well before their occurrence. The seismicity is observed to fluctuate in the order of low-high-low ranging from 0-0.5, 01-33 to 0-0.7 events/year prior to these mainshocks during the epochs of normal/background, swarm/anomalous and gap/quiescence, respectively. The duration of precursory gap is observed to vary from 11 to 17 years for mainshocks of M 7.5-8.0, and from 23 to 27 years for M 8.7 and this period is dependent on the magnitude of the mainshocks. Using the values of magnitude of mainshock ( Mm), average magnitude of swarm ( Mp) and the precursory time gap ( Tp), the following predictive equations are established for the region: M=1.37M-1.40 M=3log⁡T-3.27 All the major earthquakes with mb ≥ 6.1 occurred during 1963-1988 have been investigated for their association with anomalous seismicity/precursory swarms using the events with cutoff magnitude mb ≥ 4.5. Eleven such events have occurred in the region during the period except one earthquake of 29 May 1976. All the remaining 10 earthquakes were associated in some forms of anomalous seismicity epochs. Well-defined patterns of anomalous seismicity are observed prior to 1964-1965, 12 August 1976 and 30 December 1984 ( mb 5.6). All these mainshocks are preceded by seismicity patterns in the order of low-high-low similar to that observed prior to the mainshocks from 1897 to 1962. The anomalous seismicity epoch is delineated with extremely high annual earthquake frequency, which was preceded and followed by extremely low

  10. Early science with the large millimeter telescope: exploring the