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Sample records for bowel slow wave

  1. Slow frictional waves

    Science.gov (United States)

    Viswanathan, Koushik; Sundaram, Narayan; Chandrasekar, Srinivasan

    Stick-slip, manifest as intermittent tangential motion between two dry solid surfaces, is a friction instability that governs diverse phenomena from automobile brake squeals to earthquakes. We show, using high-speed in situ imaging of an adhesive polymer interface, that low velocity stick-slip is fundamentally of three kinds, corresponding to passage of three different surface waves -- separation pulses, slip pulses and the well-known Schallamach waves. These waves, traveling much slower than elastic waves, have clear distinguishing properties. Separation pulses and Schallamach waves involve local interface separation, and propagate in opposite directions while slip pulses are characterized by a sharp stress front and do not display any interface detachment. A change in the stick-slip mode from separation to slip pulse is effected simply by increasing the normal force. Together, these three waves constitute all possible stick-slip modes in adhesive friction and are shown to have direct analogues in muscular locomotory waves in soft bodied invertebrates. A theory for slow wave propagation is also presented which is capable of explaining the attendant interface displacements, velocities and stresses.

  2. Slow wave propagation in soft adhesive interfaces.

    Science.gov (United States)

    Viswanathan, Koushik; Sundaram, Narayan K; Chandrasekar, Srinivasan

    2016-11-16

    Stick-slip in sliding of soft adhesive surfaces has long been associated with the propagation of Schallamach waves, a type of slow surface wave. Recently it was demonstrated using in situ experiments that two other kinds of slow waves-separation pulses and slip pulses-also mediate stick-slip (Viswanathan et al., Soft Matter, 2016, 12, 5265-5275). While separation pulses, like Schallamach waves, involve local interface detachment, slip pulses are moving stress fronts with no detachment. Here, we present a theoretical analysis of the propagation of these three waves in a linear elastodynamics framework. Different boundary conditions apply depending on whether or not local interface detachment occurs. It is shown that the interface dynamics accompanying slow waves is governed by a system of integral equations. Closed-form analytical expressions are obtained for the interfacial pressure, shear stress, displacements and velocities. Separation pulses and Schallamach waves emerge naturally as wave solutions of the integral equations, with oppositely oriented directions of propagation. Wave propagation is found to be stable in the stress regime where linearized elasticity is a physically valid approximation. Interestingly, the analysis reveals that slow traveling wave solutions are not possible in a Coulomb friction framework for slip pulses. The theory provides a unified picture of stick-slip dynamics and slow wave propagation in adhesive contacts, consistent with experimental observations.

  3. Automated classification of spatiotemporal characteristics of gastric slow wave propagation.

    Science.gov (United States)

    Paskaranandavadivel, Niranchan; Gao, Jerry; Du, Peng; O'Grady, Gregory; Cheng, Leo K

    2013-01-01

    Gastric contractions are underpinned by an electrical event called slow wave activity. High-resolution electrical mapping has recently been adapted to study gastric slow waves at a high spatiotemporal detail. As more slow wave data becomes available, it is becoming evident that the spatial organization of slow wave plays a key role in the initiation and maintenance of gastric dsyrhythmias in major gastric motility disorders. All of the existing slow wave signal processing techniques deal with the identification and partitioning of recorded wave events, but not the analysis of the slow wave spatial organization, which is currently performed visually. This manual analysis is time consuming and is prone to observer bias and error. We present an automated approach to classify spatial slow wave propagation patterns via the use of Pearson cross correlations. Slow wave propagations were grouped into classes based on their similarity to each other. The method was applied to high-resolution gastric slow wave recordings from four pigs. There were significant changes in the velocity of the gastric slow wave wavefront and the amplitude of the slow wave event when there was a change in direction to the slow wave wavefront during dsyrhythmias, which could be detected with the automated approach.

  4. Slow Wave Sleep and Long Duration Spaceflight

    Science.gov (United States)

    Whitmire, Alexandra; Orr, Martin; Arias, Diana; Rueger, Melanie; Johnston, Smith; Leveton, Lauren

    2012-01-01

    While ground research has clearly shown that preserving adequate quantities of sleep is essential for optimal health and performance, changes in the progression, order and /or duration of specific stages of sleep is also associated with deleterious outcomes. As seen in Figure 1, in healthy individuals, REM and Non-REM sleep alternate cyclically, with stages of Non-REM sleep structured chronologically. In the early parts of the night, for instance, Non-REM stages 3 and 4 (Slow Wave Sleep, or SWS) last longer while REM sleep spans shorter; as night progresses, the length of SWS is reduced as REM sleep lengthens. This process allows for SWS to establish precedence , with increases in SWS seen when recovering from sleep deprivation. SWS is indeed regarded as the most restorative portion of sleep. During SWS, physiological activities such as hormone secretion, muscle recovery, and immune responses are underway, while neurological processes required for long term learning and memory consolidation, also occur. The structure and duration of specific sleep stages may vary independent of total sleep duration, and changes in the structure and duration have been shown to be associated with deleterious outcomes. Individuals with narcolepsy enter sleep through REM as opposed to stage 1 of NREM. Disrupting slow wave sleep for several consecutive nights without reducing total sleep duration or sleep efficiency is associated with decreased pain threshold, increased discomfort, fatigue, and the inflammatory flare response in skin. Depression has been shown to be associated with a reduction of slow wave sleep and increased REM sleep. Given research that shows deleterious outcomes are associated with changes in sleep structure, it is essential to characterize and mitigate not only total sleep duration, but also changes in sleep stages.

  5. Coupling between whistler waves and slow-mode solitary waves

    CERN Document Server

    Tenerani, Anna; Pegoraro, Francesco; Contel, Olivier Le

    2012-01-01

    The interplay between electron-scale and ion-scale phenomena is of general interest for both laboratory and space plasma physics. In this paper we investigate the linear coupling between whistler waves and slow magnetosonic solitons through two-fluid numerical simulations. Whistler waves can be trapped in the presence of inhomogeneous external fields such as a density hump or hole where they can propagate for times much longer than their characteristic time scale, as shown by laboratory experiments and space measurements. Space measurements have detected whistler waves also in correspondence to magnetic holes, i.e., to density humps with magnetic field minima extending on ion-scales. This raises the interesting question of how ion-scale structures can couple to whistler waves. Slow magnetosonic solitons share some of the main features of a magnetic hole. Using the ducting properties of an inhomogeneous plasma as a guide, we present a numerical study of whistler waves that are trapped and transported inside pr...

  6. Enhancement of sleep slow waves: underlying mechanisms and practical consequences.

    OpenAIRE

    Michele eBellesi; Brady A Riedner; Garcia-Molina, Gary N.; Chiara eCirelli; Giulio eTononi

    2014-01-01

    Even modest sleep restriction, especially the loss of sleep slow wave activity, is invariably associated with slower EEG activity during wake, the occurrence of local sleep in an otherwise awake brain, and impaired performance due to cognitive and memory deficits. Recent studies not only confirm the beneficial role of sleep in memory consolidation, but also point to a specific role for sleep slow waves. Thus, the implementation of methods to enhance sleep slow waves without unwanted arousals ...

  7. Damping of Slow Magnetoacoustic Waves in an Inhomogeneous Coronal Plasma

    Indian Academy of Sciences (India)

    Nagendra Kumar; Pradeep Kumar; Shiv Singh; Anil Kumar

    2008-03-01

    We study the propagation and dissipation of slow magnetoacoustic waves in an inhomogeneous viscous coronal loop plasma permeated by uniform magnetic field. Only viscosity and thermal conductivity are taken into account as dissipative processes in the coronal loop. The damping length of slow-mode waves exhibit varying behaviour depending upon the physical parameters of the loop in an active region AR8270 observed by TRACE. The wave energy flux associated with slow magnetoacoustic waves turns out to be of the order of 106 erg cm-2 s-1 which is high enough to replace the energy lost through optically thin coronal emission and the thermal conduction belowto the transition region. It is also found that only those slow-mode waves which have periods more than 240 s provide the required heating rate to balance the energy losses in the solar corona. Our calculated wave periods for slow-mode waves nearly match with the oscillation periods of loop observed by TRACE.

  8. Enhancement of sleep slow waves: underlying mechanisms and practical consequences.

    Directory of Open Access Journals (Sweden)

    Michele eBellesi

    2014-10-01

    Full Text Available Even modest sleep restriction, especially the loss of sleep slow wave activity, is invariably associated with slower EEG activity during wake, the occurrence of local sleep in an otherwise awake brain, and impaired performance due to cognitive and memory deficits. Recent studies not only confirm the beneficial role of sleep in memory consolidation, but also point to a specific role for sleep slow waves. Thus, the implementation of methods to enhance sleep slow waves without unwanted arousals or lightening of sleep could have significant practical implications. Here we first review the evidence that it is possible to enhance sleep slow waves in humans using transcranial direct-current stimulation and transcranial magnetic stimulation. Since these methods are currently impractical and their safety is questionable, especially for chronic long-term exposure, we then discuss novel data suggesting that it is possible to enhance slow waves using sensory stimuli. We consider the physiology of the K-complex, a peripheral evoked slow wave, and show that, among different sensory modalities, acoustic stimulation is the most effective in increasing the magnitude of slow waves, likely through the activation of non-lemniscal ascending pathways to the thalamo-cortical system. In addition, we discuss how intensity and frequency of the acoustic stimuli, as well as exact timing and pattern of stimulation, affect sleep enhancement. Finally, we discuss automated algorithms that read the EEG and, in real-time, adjust the stimulation parameters in a closed-loop manner to obtain an increase in sleep slow waves and avoid undesirable arousals. In conclusion, while discussing the mechanisms that underlie the generation of sleep slow waves, we review the converging evidence showing that acoustic stimulation is safe and represents an ideal tool for slow wave sleep enhancement.

  9. Enhancement of sleep slow waves: underlying mechanisms and practical consequences.

    Science.gov (United States)

    Bellesi, Michele; Riedner, Brady A; Garcia-Molina, Gary N; Cirelli, Chiara; Tononi, Giulio

    2014-01-01

    Even modest sleep restriction, especially the loss of sleep slow wave activity (SWA), is invariably associated with slower electroencephalogram (EEG) activity during wake, the occurrence of local sleep in an otherwise awake brain, and impaired performance due to cognitive and memory deficits. Recent studies not only confirm the beneficial role of sleep in memory consolidation, but also point to a specific role for sleep slow waves. Thus, the implementation of methods to enhance sleep slow waves without unwanted arousals or lightening of sleep could have significant practical implications. Here we first review the evidence that it is possible to enhance sleep slow waves in humans using transcranial direct-current stimulation (tDCS) and transcranial magnetic stimulation. Since these methods are currently impractical and their safety is questionable, especially for chronic long-term exposure, we then discuss novel data suggesting that it is possible to enhance slow waves using sensory stimuli. We consider the physiology of the K-complex (KC), a peripheral evoked slow wave, and show that, among different sensory modalities, acoustic stimulation is the most effective in increasing the magnitude of slow waves, likely through the activation of non-lemniscal ascending pathways to the thalamo-cortical system. In addition, we discuss how intensity and frequency of the acoustic stimuli, as well as exact timing and pattern of stimulation, affect sleep enhancement. Finally, we discuss automated algorithms that read the EEG and, in real-time, adjust the stimulation parameters in a closed-loop manner to obtain an increase in sleep slow waves and avoid undesirable arousals. In conclusion, while discussing the mechanisms that underlie the generation of sleep slow waves, we review the converging evidence showing that acoustic stimulation is safe and represents an ideal tool for slow wave sleep (SWS) enhancement.

  10. Slow waves, sharp waves, ripples, and REM in sleeping dragons.

    Science.gov (United States)

    Shein-Idelson, Mark; Ondracek, Janie M; Liaw, Hua-Peng; Reiter, Sam; Laurent, Gilles

    2016-04-29

    Sleep has been described in animals ranging from worms to humans. Yet the electrophysiological characteristics of brain sleep, such as slow-wave (SW) and rapid eye movement (REM) activities, are thought to be restricted to mammals and birds. Recording from the brain of a lizard, the Australian dragon Pogona vitticeps, we identified SW and REM sleep patterns, thus pushing back the probable evolution of these dynamics at least to the emergence of amniotes. The SW and REM sleep patterns that we observed in lizards oscillated continuously for 6 to 10 hours with a period of ~80 seconds. The networks controlling SW-REM antagonism in amniotes may thus originate from a common, ancient oscillator circuit. Lizard SW dynamics closely resemble those observed in rodent hippocampal CA1, yet they originate from a brain area, the dorsal ventricular ridge, that has no obvious hodological similarity with the mammalian hippocampus.

  11. Excitation of surface plasma waves over corrugated slow-wave structure

    Indian Academy of Sciences (India)

    Ashim P Jain; Jetendra Parashar

    2005-08-01

    A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between dielectric and slow-wave structure. These slow SPW can couple the microwave energy to the plasma and can sustain the discharge. The efficiency of the power coupling is few per cent and is sensitive to separation between dielectric and slow-wave structure.

  12. Global intracellular slow-wave dynamics of the thalamocortical system.

    Science.gov (United States)

    Sheroziya, Maxim; Timofeev, Igor

    2014-06-25

    It is widely accepted that corticothalamic neurons recruit the thalamus in slow oscillation, but global slow-wave thalamocortical dynamics have never been experimentally shown. We analyzed intracellular activities of neurons either from different cortical areas or from a variety of specific and nonspecific thalamic nuclei in relation to the phase of global EEG signal in ketamine-xylazine anesthetized mice. We found that, on average, slow-wave active states started off within frontal cortical areas as well as higher-order and intralaminar thalamus (posterior and parafascicular nuclei) simultaneously. Then, the leading edge of active states propagated in the anteroposterior/lateral direction over the cortex at ∼40 mm/s. The latest structure we recorded within the slow-wave cycle was the anterior thalamus, which followed active states of the retrosplenial cortex. Active states from different cortical areas tended to terminate simultaneously. Sensory thalamic ventral posterior medial and lateral geniculate nuclei followed cortical active states with major inhibitory and weak tonic-like "modulator" EPSPs. In these nuclei, sharp-rising, large-amplitude EPSPs ("drivers") were not modulated by cortical slow waves, suggesting their origin in ascending pathways. The thalamic active states in other investigated nuclei were composed of depolarization: some revealing "driver"- and "modulator"-like EPSPs, others showing "modulator"-like EPSPs only. We conclude that sensory thalamic nuclei follow the propagating cortical waves, whereas neurons from higher-order thalamic nuclei display "hub dynamics" and thus may contribute to the generation of cortical slow waves.

  13. Study of Novel Slow Wave Circuit for Miniaturized Millimeter Wave Helical Traveling Wave Tube

    Science.gov (United States)

    Li, Bin; Zhu, Xiaofang; Liao, Li; Yang, Zhonghai; Zeng, Baoqing; Yao, Lieming

    2006-07-01

    Two kinds of novel helical slow wave circuit, supported by Chemical Vapor Deposition (CVD) diamond, are presented. They are applying in miniaturized millimeter wave helical traveling wave tube. Cold test characteristic of these circuits are simulated by MAFIA code. Higher performances are achieved with smaller size, compared with conventional circuit supported by BeO rods. The nonlinear analysis is implemented by Beam and Wave Interaction (BWI) module, which is a part of TWTCAD Integrated Framework. Results have been found to be consistent with the expectation. It should be wider apply in microwave and millimeter wave vacuum electronic devices.

  14. Properties of slow oscillation during slow-wave sleep and anesthesia in cats

    Science.gov (United States)

    Chauvette, Sylvain; Crochet, Sylvain; Volgushev, Maxim; Timofeev, Igor

    2011-01-01

    Deep anesthesia is commonly used as a model of slow-wave sleep (SWS). Ketamine-xylazine anesthesia reproduces the main features of sleep slow oscillation: slow, large amplitude waves in field potential, which are generated by the alternation of hyperpolarized and depolarized states of cortical neurons. However, direct quantitative comparison of field potential and membrane potential fluctuations during natural sleep and anesthesia is lacking, so it remains unclear how well the properties of sleep slow oscillation are reproduced by the ketamine-xylazine anesthesia model. Here, we used field potential and intracellular recordings in different cortical areas in the cat, to directly compare properties of slow oscillation during natural sleep and ketamine-xylazine anesthesia. During SWS cortical activity showed higher power in the slow/delta (0.1-4 Hz) and spindle (8-14 Hz) frequency range, while under anesthesia the power in the gamma band (30-100 Hz) was higher. During anesthesia, slow waves were more rhythmic and more synchronous across the cortex. Intracellular recordings revealed that silent states were longer and the amplitude of membrane potential around transition between active and silent states was bigger under anesthesia. Slow waves were largely uniform across cortical areas under anesthesia, but in SWS they were most pronounced in associative and visual areas, but smaller and less regular in somatosensory and motor cortices. We conclude that although the main features of the slow oscillation in sleep and anesthesia appear similar, multiple cellular and network features are differently expressed during natural SWS as compared to ketamine-xylazine anesthesia. PMID:22016533

  15. Properties of slow oscillation during slow-wave sleep and anesthesia in cats.

    Science.gov (United States)

    Chauvette, Sylvain; Crochet, Sylvain; Volgushev, Maxim; Timofeev, Igor

    2011-10-19

    Deep anesthesia is commonly used as a model of slow-wave sleep (SWS). Ketamine-xylazine anesthesia reproduces the main features of sleep slow oscillation: slow, large-amplitude waves in field potential, which are generated by the alternation of hyperpolarized and depolarized states of cortical neurons. However, direct quantitative comparison of field potential and membrane potential fluctuations during natural sleep and anesthesia is lacking, so it remains unclear how well the properties of sleep slow oscillation are reproduced by the ketamine-xylazine anesthesia model. Here, we used field potential and intracellular recordings in different cortical areas in the cat to directly compare properties of slow oscillation during natural sleep and ketamine-xylazine anesthesia. During SWS cortical activity showed higher power in the slow/delta (0.1-4 Hz) and spindle (8-14 Hz) frequency range, whereas under anesthesia the power in the gamma band (30-100 Hz) was higher. During anesthesia, slow waves were more rhythmic and more synchronous across the cortex. Intracellular recordings revealed that silent states were longer and the amplitude of membrane potential around transition between active and silent states was bigger under anesthesia. Slow waves were mostly uniform across cortical areas under anesthesia, but in SWS, they were most pronounced in associative and visual areas but smaller and less regular in somatosensory and motor cortices. We conclude that, although the main features of the slow oscillation in sleep and anesthesia appear similar, multiple cellular and network features are differently expressed during natural SWS compared with ketamine-xylazine anesthesia.

  16. ON THE SOURCE OF PROPAGATING SLOW MAGNETOACOUSTIC WAVES IN SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, S. Krishna; Jess, D. B. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Khomenko, Elena, E-mail: krishna.prasad@qub.ac.uk [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2015-10-10

    Recent high-resolution observations of sunspot oscillations using simultaneously operated ground- and space-based telescopes reveal the intrinsic connection between different layers of the solar atmosphere. However, it is not clear whether these oscillations are externally driven or generated in situ. We address this question by using observations of propagating slow magnetoacoustic waves along a coronal fan loop system. In addition to the generally observed decreases in oscillation amplitudes with distance, the observed wave amplitudes are also found to be modulated with time, with similar variations observed throughout the propagation path of the wave train. Employing multi-wavelength and multi-instrument data, we study the amplitude variations with time as the waves propagate through different layers of the solar atmosphere. By comparing the amplitude modulation period in different layers, we find that slow magnetoacoustic waves observed in sunspots are externally driven by photospheric p-modes, which propagate upward into the corona before becoming dissipated.

  17. Dispersion Characteristics of a New Slow-Wave Structure

    Institute of Scientific and Technical Information of China (English)

    WU Jian-Qiang

    2004-01-01

    @@ The microwave excitation in a new slow-wave structure, i.e. the plasma-filled coaxial cylindrical dielectric-loaded cylindrical waveguide, is investigated by using the self-consistent linear field theory in considering the collision effect between electrons and ions in the plasma via the collision frequency term. The determinant dispersion equation of the beam-wave interaction with a complex value of angular frequency is derived. The effects of plasma collision frequency on the output frequency and the wave growth rate of the beam-wave interaction are calculated and discussed.

  18. Wide-band slow-wave systems simulation and applications

    CERN Document Server

    Staras, Stanislovas

    2012-01-01

    The field of electromagnetics has seen considerable advances in recent years, based on the wide applications of numerical methods for investigating electromagnetic fields, microwaves, and other devices. Wide-Band Slow-Wave Systems: Simulation and Applications presents new technical solutions and research results for the analysis, synthesis, and design of slow-wave structures for modern electronic devices with super-wide pass-bands. It makes available, for the first time in English, significant research from the past 20 years that was previously published only in Russian and Lithuanian. The aut

  19. Slow waves in locally resonant metamaterials line defect waveguides

    CERN Document Server

    Kaina, Nadège; Bourlier, Yoan; Fink, Mathias; Berthelot, Thomas; Lerosey, Geoffroy

    2016-01-01

    The ability of electromagnetic waves to interact with matter governs many fascinating effects involved in fundamental and applied, quantum and classical physics. It is necessary to enhance these otherwise naturally weak effects by increasing the probability of wave/matter interactions, either through field confinement or slowing down of waves. This is commonly achieved with structured materials such as photonic crystal waveguides or coupled resonator optical waveguides. Yet their minimum structural scale is limited to the order of the wavelength which not only forbids ultra-small confinement but also severely limits their performance for slowing down waves. Here we show that line defect waveguides in locally resonant metamaterials can outperform these proposals due to their deep subwavelength scale. We experimentally demonstrate our approach in the microwave domain using 3D printed resonant wire metamaterials, achieving group indices ng as high as 227 over relatively wide frequency bands. Those results corres...

  20. Submillimeter Wave Antenna With Slow Wave Feed Line

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Krozer, Viktor; Kotiranta, Mikko

    2009-01-01

    Submillimeter wave radiation, which is also referred to as terahertz radiation, has not been extensively explored until recently due to a lack of reliable components and devices in this frequency range. Current advances in technology have made it possible to explore this portion...... of the electromagnetic spectrum, and to create innovative imaging and sensing techniques that hold enormous potential in biomedical, metrological and security applications. Considering that realization of submillimeter wave components and antennas is still heavily constrained by problems arising from technological...... to directly radiate energy from a vane-type interaction structure of a vacuum electron device. The parameters of the antenna are optimized while taking the technological constraints into account....

  1. Slow magnetosonic waves and fast flows in active region loops

    CERN Document Server

    Ofman, Leon; Davila, Joseph M

    2012-01-01

    Recent EUV spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (~100-300 km/s) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux-tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast mode waves. The phase speed of the slow magn...

  2. Standing Slow MHD Waves in Radiatively Cooling Coronal Loops

    Indian Academy of Sciences (India)

    K. S. Al-Ghafri

    2015-06-01

    The standing slow magneto-acoustic oscillations in cooling coronal loops are investigated. There are two damping mechanisms which are considered to generate the standing acoustic modes in coronal magnetic loops, namely, thermal conduction and radiation. The background temperature is assumed to change temporally due to optically thin radiation. In particular, the background plasma is assumed to be radiatively cooling. The effects of cooling on longitudinal slow MHD modes is analytically evaluated by choosing a simple form of radiative function, that ensures the temperature evolution of the background plasma due to radiation, coincides with the observed cooling profile of coronal loops. The assumption of low-beta plasma leads to neglecting the magnetic field perturbation and, eventually, reduces the MHD equations to a 1D system modelling longitudinal MHD oscillations in a cooling coronal loop. The cooling is assumed to occur on a characteristic time scale, much larger than the oscillation period that subsequently enables using the WKB theory to study the properties of standing wave. The governing equation describing the time-dependent amplitude of waves is obtained and solved analytically. The analytically derived solutions are numerically evaluated to give further insight into the evolution of the standing acoustic waves. We find that the plasma cooling gives rise to a decrease in the amplitude of oscillations. In spite of the reduction in damping rate caused by rising the cooling, the damping scenario of slow standing MHD waves strongly increases in hot coronal loops.

  3. Plasma depletion layer: the role of the slow mode waves

    Directory of Open Access Journals (Sweden)

    Y. L. Wang

    2004-12-01

    Full Text Available The plasma depletion layer (PDL is a layer on the sunward side of the magnetopause with lower plasma density and higher magnetic field compared to their corresponding values in the upstream magnetosheath. The depletion layer usually occurs during northward (IMF conditions with low magnetic shear across the magnetopause. We have previously validated the Raeder global model by comparing the computed formation of a magnetosheath density depletion with in-situ observations. We also have performed a detailed force analysis and found the varying roles that different MHD forces play along the path of a plasma parcel flowing around the magnetopause. That study resulted in a new description of the behavior of magnetosheath magnetic flux tubes which better explains the plasma depletion along a flux tube. The slow mode waves have been observed in the magnetosheath and have been used to explain the formation of the PDL in some of the important PDL models. In this study, we extend our former work by investigating the possible role of the slow mode waves for the formation of the PDL, using global MHD model simulations. We propose a new technique to test where a possible slow mode front may occur in the magnetosheath by comparing the slow mode group velocity with the local flow velocity. We find that the slow mode fronts can exist in certain regions in the magnetosheath under certain solar wind conditions. The existence and location of such fronts clearly depend on the IMF. We do not see from our global simulation results either the sharpening of the slow mode front into a slow mode shock or noticeable changes of the flow and field in the magnetosheath across the slow mode front, which implies that the slow mode front is not likely responsible for the formation of the PDL, at least for the stable solar wind conditions used in these simulations. Also, we do not see the two-layered slow mode structures shown in some observations and proposed in certain PDL

  4. The puzzle of decreased homeostatic slow wave sleep in aging

    OpenAIRE

    Rytkönen, Kirsi-Marja

    2012-01-01

    Slow wave sleep is the most important part of sleep, yet it decreases with aging. Staying awake puts pressure on the neurons of the brain s arousal systems, e.g. on the cortically projecting neurons of the basal forebrain. During wakefulness, these neurons are active and excite the cortex, thereby enhancing behavioral arousal. Sleep quality and duration are compromised with increasing age. Elderly people often experience these symptoms as sleep problems and contact medical professionals. Trea...

  5. Slow Wave Characteristics of Helix Structure with Elliptical Cross Section

    Institute of Scientific and Technical Information of China (English)

    XIE Jian-Xiang; WEI Yan-Yu; GONG Yu-Bin; Fu Cheng-Fang; YUE Ling-Na; WANG Wen-Xiang

    2007-01-01

    We present a novel helix slow wave structure with an elliptical cross section shielded by an elliptical waveguide.The rf characteristics including dispersion properties,interaction impedance of zero mode in this structure have been studied in detail.The theoretical results reveal that weaker dispersion even abnormal dispersion characteristics is obtained with the increasing eccentricity of the elliptical waveguide,while the interaction impedance is enhanced by enlarging the eccentricity of elliptical helix.

  6. Plastic-Flow Waves ("Slow-Waves") and Seismic Activity in Central-Eastern Asia

    Institute of Scientific and Technical Information of China (English)

    Wang Shengzu; Zhang Zongchun

    2005-01-01

    The results inferred from experiments with analogue models carried out previously have shown that two types of plastic-flow waves, "fast-waves" and "slow-waves", are induced in the lower lithosphere (including the lower crust and lithospheric mantle ) under driving at plate boundaries and both of them are viscous gravity waves formed by the superposition of major and subsidiary waves. The major waves are similar to solitary waves and the subsidiary waves are traveling waves. The plastic-flow waves in the lower lithosphere control seismic activities in the overlying seismogenic layer and result in the distribution of earthquakes along the wavecrest belts. "Fast-waves" propagated with velocities of orders of magnitude of 100 ~ 102km/a have been verified by wave-controlled earthquake migration, showing the "decade waves" and "century waves" with the average periods of 10.8 and 93.4 a, respectively, which originate from the Himalayan driving boundary. According to the recognition of the patterns of the beltlike distribution of strong earthquakes with Ms ≥ 7.0, it is indicated further in this paper that the "slow-waves" with velocities of orders of magnitude of 100 ~ 101 m/a also originated under compression from the Himalayan driving boundary. Strong earthquakes with Ms ≥ 7.0 are controlled mainly by subsidiary waves, because the major waves with a duration of up to 106 a for each disturbance cannot result in the accmnulation of enough energy for strong earthquakes due to the relaxation of the upper crust. The subsidiary waves propagate with an average wave length of 445 km, velocities of 0.81~2.80 m/a and periods of 0.16 ~ 0.55 Ma. The wavegenerating time at the Himalayan driving boundary is about 1.34 ~ 4.59 Ma before present for the "slow-waves", corresponding to the stage from the Mid Pliocene to the Mid EarlyPleistocene and being identical with one of the major tectonic episodes of the Himalayan tectonic movement. It is shown from the recognition of

  7. Comparative research on three types of coaxial slow wave structures

    Institute of Scientific and Technical Information of China (English)

    Xiao Ren-Zhen; Liu Guo-Zhi; Chen Chang-Hua

    2008-01-01

    This paper studies three types of coaxial slow wave structures(SWSs):(1)with ripples on both the inner and outer conductors;(2)with ripples on the outer conductor and smooth on the inner one;and(3)with ripples on the inner conductor and smooth on the outer one.The frequencies,coupling impedances,time growth rates and beam-wave interaction efficiencies of the three types of coaxial SWSs are obtained by theoretical analysis.Moreover,the relativistic Cerenkov generators(RCGs)with the three types of coaxial SWSs are simulated with a fully electromagnetic particle-in-cell code,and the results verify the theoretical analysis.It is proved that the RCG with double-rippled coaxial SWS has the highest conversion efficiency and the shortest starting time.

  8. Characteristics of Short-wavelength Oblique Alfven and Slow waves

    CERN Document Server

    Zhao, J S; Yu, M Y; Lu, J Y; Wu, D J

    2014-01-01

    Linear properties of kinetic Alfv\\'en waves (KAWs) and kinetic slow waves (KSWs) are studied in the framework of two-fluid magnetohydrodynamics. We obtain the wave dispersion relations that are valid in a wide range of the wave frequency {\\omega} and plasma-to-magnetic pressure ratio {\\beta}. The KAW frequency can reach and exceed the ion cyclotron frequency at ion kinetic scales, whereas the KSW frequency remains sub-cyclotron. At {\\beta}\\sim1, the plasma and magnetic pressure perturbations of both modes are in anti-phase, so that there is nearly no total pressure perturbations. However, these modes exhibit several different properties. At high {\\beta}, the electric field polarization of KAW and KSW is opposite at the ion gyroradius scale, where KAWs are polarized in sense of electron gyration (right-hand polarized) and KSWs are left-hand polarized. The magnetic helicity {\\sigma}\\sim1 for KAWs and {\\sigma}\\sim-1 for KSWs, and the ion Alfv\\'en ratio R_{Ai}\\ll 1 for KAWs and R_{Ai}\\gg 1 for KSWs. We also found...

  9. Multiple slow waves in metaporous layers for broadband sound absorption

    Science.gov (United States)

    Yang, Jieun; Lee, Joong Seok; Kim, Yoon Young

    2017-01-01

    Sound absorption for a broad frequency range requires sound dissipation. The mechanics of acoustic metamaterials for non-dissipative applications has been extensively studied, but sound absorption using dissipative porous metamaterials has been less explored because of the complexity resulting from the coupling of its dissipative mechanism and metamaterial behavior. We investigated broadband sound absorption by engineering dissipative metaporous layers, which absorb sound by the mechanism of multiple slow waves, and combined local and global resonance phenomena. A set of rigid partitions of varying lengths was elaborately inserted in a hard-backed porous layer of a finite thickness. An effective medium theory was used to explain the physics involved; high performance at a low-frequency range was found to be mainly due to the formation of global resonances caused by multiple slow waves over the thickness of the metaporous layer, while enhancement at a high-frequency range was attributed to the combined effects of the global resonances and the local resonances directly related to the sizes of the inserted partitions.

  10. Comparing the Robustness of High-Frequency Traveling-Wave Tube Slow-Wave Circuits

    Science.gov (United States)

    Chevalier, Christine T.; Wilson, Jeffrey D.; Kory, Carol L.

    2007-01-01

    A three-dimensional electromagnetic field simulation software package was used to compute the cold-test parameters, phase velocity, on-axis interaction impedance, and attenuation, for several high-frequency traveling-wave tube slow-wave circuit geometries. This research effort determined the effects of variations in circuit dimensions on cold-test performance. The parameter variations were based on the tolerances of conventional micromachining techniques.

  11. Research of sine waveguide slow-wave structure for a 220-GHz backward wave oscillator

    Institute of Scientific and Technical Information of China (English)

    Xu Xiong; Wei Yan-Yu; Shen Fei; Huang Min-Zhi; Tang Tao; Duan Zhao-Yun; Gong Yu-Bin

    2012-01-01

    A watt-class backward wave oscillator is proposed,using the concise sine waveguide slow-wave structure combined with a pencil electron beam to operate at 220 GHz.Firstly,the dispersion curve of the sine waveguide is calculated,then,the oscillation frequency and operating voltage of the device are predicted and the circuit transmission loss is calculated.Finally,the particle-in-cell simulation method is used to forecast its radiation performance.The results show that this novel backward wave oscillator can produce over 1-W continuous wave power output in a frequency range from 210 GHz to 230 GHz.Therefore,it will be considered as a very promising high-power millimeter-wave to terahertz-wave radiation source.

  12. Stability of Brillouin Flow in Slow-Wave Structures

    Science.gov (United States)

    Simon, David; Lau, Y. Y.; Greening, Geoffrey; Wong, Patrick; Gilgenbach, Ronald; Hoff, Brad

    2016-10-01

    For the first time, we include a slow-wave structure (SWS) to study the stability of Brillouin flow in the conventional, planar, and inverted magnetron geometry. The resonant interaction of the SWS circuit mode and the corresponding smooth-bore diocotron-like mode is found to be the dominant cause for instability, overwhelming the intrinsic negative (positive) mass property of electrons in the inverted (conventional) magnetron geometry. It severely restricts the wavenumber for instability to the narrow range in which the cold tube frequency of the SWS is within a few percent of the corresponding smooth bore diocotron-like mode in the Brillouin flow. This resonant interaction is absent in a smooth bore magnetron. Work supported by ONR N00014-13-1-0566 and N00014-16-1-2353, AFOSR FA9550-15-1-0097, and L-3 Communications Electron Device Division.

  13. Light transmission through and its complete stoppage in an ultra slow wave optical medium

    CERN Document Server

    V., Ranjith

    2013-01-01

    Light Wave transmission -- its compression, amplification, and the optical energy storage -- in an Ultra Slow Wave Medium (USWM) is studied analytically. Our phenomenological treatment is based entirely on the continuity equation for the optical energy flux, and the well known distribution-product property of Dirac delta-function. The results so obtained provide a clear understanding of some recent experiments on light transmission and its complete stoppage in an USWM. Keywords : Ultra slow light, stopped light, slow wave medium, EIT.

  14. Characterization of slow waves generated by myenteric interstitial cells of Cajal of the rabbit small intestine.

    Science.gov (United States)

    Kito, Yoshihiko; Mitsui, Retsu; Ward, Sean M; Sanders, Kenton M

    2015-03-01

    Slow waves (slow wavesICC) were recorded from myenteric interstitial cells of Cajal (ICC-MY) in situ in the rabbit small intestine, and their properties were compared with those of mouse small intestine. Rabbit slow wavesICC consisted of an upstroke depolarization followed by a distinct plateau component. Ni(2+) and nominally Ca(2+)-free solutions reduced the rate-of-rise and amplitude of the upstroke depolarization. Replacement of Ca(2+) with Sr(2+) enhanced the upstroke component but decreased the plateau component of rabbit slow wavesICC. In contrast, replacing Ca(2+) with Sr(2+) decreased both components of mouse slow wavesICC. The plateau component of rabbit slow wavesICC was inhibited in low-extracellular-Cl(-)-concentration (low-[Cl(-)]o) solutions and by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of Cl(-) channels, cyclopiazonic acid (CPA), an inhibitor of internal Ca(2+) pumps, or bumetanide, an inhibitor of Na(+)-K(+)-2Cl(-) cotransporter (NKCC1). Bumetanide also inhibited the plateau component of mouse slow wavesICC. NKCC1-like immunoreactivity was observed mainly in ICC-MY in the rabbit small intestine. Membrane depolarization with a high-K(+) solution reduced the upstroke component of rabbit slow wavesICC. In cells depolarized with elevated external K(+), DIDS, CPA, and bumetanide blocked slow wavesICC. These results suggest that the upstroke component of rabbit slow wavesICC is partially mediated by voltage-dependent Ca(2+) influx, whereas the plateau component is dependent on Ca(2+)-activated Cl(-) efflux. NKCC1 is likely to be responsible for Cl(-) accumulation in ICC-MY. The results also suggest that the mechanism of the upstroke component differs in rabbit and mouse slow wavesICC in the small intestine.

  15. Masculine sexual activity affects slow wave sleep in Golden hamsters.

    Science.gov (United States)

    Jiménez-Anguiano, A; Arteaga-Silva, M; Velázquez-Moctezuma, J

    2003-02-15

    The sleep pattern is modified by events occurring during wakefulness. In rats, it has been shown that male sexual behavior has a direct influence on sleeping patterns, increasing slow wave sleep (SWS) duration. On the other hand, the sexual behavior pattern of the male Golden hamster differs from the copulatory pattern of male rats. Male hamsters copulate faster and they do not display the motor inhibition observed in rats after each ejaculation. Moreover, close to exhaustion, hamsters display a behavioral pattern known as Long Intromission, which has been linked to an sexual inhibitory process. The present study was performed to determine the effects of male sexual activity on the sleep pattern in hamsters. Subjects were allowed to copulate for 30 and 60 min. In addition, the effect of locomotor activity was also assessed. The results show that male sexual behavior induced a significant increase of SWS II, with a reduction of wakefulness. No effect was observed on REM sleep. Locomotor activity produced only a slight effect on sleep. The results are discussed in terms of the similarities between the effects observed after sexual behavior on sleep in rats and hamsters, despite the substantial differences in the behavioral pattern.

  16. Thalamic Atrophy Contributes to Low Slow Wave Sleep in Neuromyelitis Optica Spectrum Disorder.

    Science.gov (United States)

    Su, Lei; Han, Yujuan; Xue, Rong; Wood, Kristofer; Shi, Fu-Dong; Liu, Yaou; Fu, Ying

    2016-12-01

    Slow wave sleep abnormality has been reported in neuromyelitis optica spectrum disorder (NMOSD), but mechanism for such abnormality is unknown. To determine the structural defects in the brain that account for the decrease of slow wave sleep in NMOSD patients. Thirty-three NMOSD patients and 18 matched healthy controls (HC) were enrolled. Polysomnography was used to monitor slow wave sleep and three-dimensional T1-weighted MRIs were obtained to assess the alterations of grey matter volume. The percentage of deep slow wave sleep decreased in 93% NMOSD patients. Compared to HC, a reduction of grey matter volume was found in the bilateral thalamus of patients with a lower percentage of slow wave sleep (FWE corrected at cluster-level, p 400 voxels). Furthermore, the right thalamic fraction was positively correlated with the decrease in the percentage of slow wave sleep in NMOSD patients (p 200 voxels). Our study identified that thalamic atrophy is associated with the decrease of slow wave sleep in NMOSD patients. Further studies should evaluate whether neurotransmitters or hormones which stem from thalamus are involved in the decrease of slow wave sleep.

  17. Thalamic Atrophy Contributes to Low Slow Wave Sleep in Neuromyelitis Optica Spectrum Disorder

    Science.gov (United States)

    Su, Lei; Han, Yujuan; Xue, Rong; Wood, Kristofer; Shi, Fu-Dong; Liu, Yaou; Fu, Ying

    2016-01-01

    Slow wave sleep abnormality has been reported in neuromyelitis optica spectrum disorder (NMOSD), but mechanism for such abnormality is unknown. To determine the structural defects in the brain that account for the decrease of slow wave sleep in NMOSD patients. Thirty-three NMOSD patients and 18 matched healthy controls (HC) were enrolled. Polysomnography was used to monitor slow wave sleep and three-dimensional T1-weighted MRIs were obtained to assess the alterations of grey matter volume. The percentage of deep slow wave sleep decreased in 93% NMOSD patients. Compared to HC, a reduction of grey matter volume was found in the bilateral thalamus of patients with a lower percentage of slow wave sleep (FWE corrected at cluster-level, p 400 voxels). Furthermore, the right thalamic fraction was positively correlated with the decrease in the percentage of slow wave sleep in NMOSD patients (p 200 voxels). Our study identified that thalamic atrophy is associated with the decrease of slow wave sleep in NMOSD patients. Further studies should evaluate whether neurotransmitters or hormones which stem from thalamus are involved in the decrease of slow wave sleep. PMID:28053819

  18. Slow wave activity and slow oscillations in sleepwalkers and controls: effects of 38 h of sleep deprivation.

    Science.gov (United States)

    Perrault, Rosemarie; Carrier, Julie; Desautels, Alex; Montplaisir, Jacques; Zadra, Antonio

    2013-08-01

    Sleepwalkers have been shown to have an unusually high number of arousals from slow wave sleep and lower slow wave activity (SWA) power during the night than controls. Because sleep deprivation increases the frequency of slow wave sleep (SWS) arousals in sleepwalkers, it may also affect the expression of the homeostatic process to a greater extent than shown previously. We thus investigated SWA power as well as slow wave oscillation (SWO) density in 10 sleepwalkers and nine controls at baseline and following 38 h of sleep deprivation. There was a significant increase in SWA during participants' recovery sleep, especially during their second non-rapid eye movement (NREM) period. SWO density was similarly increased during recovery sleep's first two NREM periods. A fronto-central gradient in SWA and SWO was also present on both nights. However, no group differences were noted on any of the 2 nights on SWA or SWO. This unexpected result may be related to the heterogeneity of sleepwalkers as a population, as well as our small sample size. SWA pressure after extended sleep deprivation may also result in a ceiling effect in both sleepwalkers and controls.

  19. Late positive slow waves as markers of chunking during encoding

    Science.gov (United States)

    Nogueira, Ana M. L.; Bueno, Orlando F. A.; Manzano, Gilberto M.; Kohn, André F.; Pompéia, Sabine

    2015-01-01

    Electrophysiological markers of chunking of words during encoding have mostly been shown in studies that present pairs of related stimuli. In these cases it is difficult to disentangle cognitive processes that reflect distinctiveness (i.e., conspicuous items because they are related), perceived association between related items and unified representations of various items, or chunking. Here, we propose a paradigm that enables the determination of a separate Event-related Potential (ERP) marker of these cognitive processes using sequentially related word triads. Twenty-three young healthy individuals viewed 80 15-word lists composed of unrelated items except for the three words in the middle serial positions (triads), which could be either unrelated (control list), related perceptually, phonetically or semantically. ERP amplitudes were measured at encoding of each one of the words in the triads. We analyzed two latency intervals (350–400 and 400–800 ms) at midline locations. Behaviorally, we observed a progressive facilitation in the immediate free recall of the words in the triads depending on the relations between their items (control < perceptual < phonetic < semantic), but only semantically related items were recalled as chunks. P300-like deflections were observed for perceptually deviant stimuli. A reduction of amplitude of a component akin to the N400 was found for words that were phonetically and semantically associated with prior items and therefore were not associated to chunking. Positive slow wave (PSW) amplitudes increased as successive phonetically and semantically related items were presented, but they were observed earlier and were more prominent at Fz for semantic associates. PSWs at Fz and Cz also correlated with recall of semantic word chunks. This confirms prior claims that PSWs at Fz are potential markers of chunking which, in the proposed paradigm, were modulated differently from the detection of deviant stimuli and of relations between

  20. Atypical slow waves generated in gastric corpus provide dominant pacemaker activity in guinea pig stomach.

    Science.gov (United States)

    Hashitani, Hikaru; Garcia-Londoño, A Pilar; Hirst, G David S; Edwards, Frank R

    2005-12-01

    When intracellular recordings were made from the circular layer of the intact muscular wall of the isolated guinea pig gastric corpus, an ongoing regular high frequency discharge of slow waves was detected even though this region lacked myenteric interstitial cells. When slow waves were recorded from preparations consisting of both the antrum and the corpus, slow waves of identical frequency, but with different shapes, were generated in the two regions. Corporal slow waves could be distinguished from antral slow waves by their time courses and amplitudes. Corporal slow waves, like antral slow waves, were abolished by buffering the internal concentration of calcium ions, [Ca2+]i, to low levels, or by caffeine, 2-aminoethoxydiphenyl borate or the chloride channel blocker DIDS. Corporal preparations demonstrated an ongoing discharge of unitary potentials, as has been found in all other tissues containing interstitial cells. The experiments show that the corpus provides the dominant pacemaker activity which entrains activity in other regions of the stomach and it is suggested that this activity is generated by corporal intramuscular interstitial cells.

  1. Slow-Mode MHD Wave Penetration into a Coronal Null Point due to the Mode Transmission

    Science.gov (United States)

    Afanasyev, Andrey N.; Uralov, Arkadiy M.

    2016-11-01

    Recent observations of magnetohydrodynamic oscillations and waves in solar active regions revealed their close link to quasi-periodic pulsations in flaring light curves. The nature of that link has not yet been understood in detail. In our analytical modelling we investigate propagation of slow magnetoacoustic waves in a solar active region, taking into account wave refraction and transmission of the slow magnetoacoustic mode into the fast one. The wave propagation is analysed in the geometrical acoustics approximation. Special attention is paid to the penetration of waves in the vicinity of a magnetic null point. The modelling has shown that the interaction of slow magnetoacoustic waves with the magnetic reconnection site is possible due to the mode transmission at the equipartition level where the sound speed is equal to the Alfvén speed. The efficiency of the transmission is also calculated.

  2. Design and Characterization of a W-Band Folded-Waveguide Slow-Wave Structure

    Science.gov (United States)

    Sumathy, Murugan; Datta, Subrata Kumar

    2016-12-01

    A single-section slow-wave structure for a W-band folded-waveguide traveling-wave tube with operating bandwidth of around 4% was designed for delivering the output power of 50 W at the operating voltage of 13.5 kV and operating beam current of 80 mA. The design was carried out using analytical formulations and 3D electromagnetic simulations. The beam-wave interaction analysis was carried out using large signal Lagrangian analysis and particle-in-cell simulation. The folded-waveguide slow-wave structure along with input-output couplers and RF windows were fabricated. Cold test measurements were carried out for dispersion characteristics of the slow-wave structure and voltage standing-wave ratio and insertion loss characteristics of the RF window. The measured cold circuit parameters show close agreement with the analysis.

  3. Unihemispheric slow-wave sleep in the Amazonian dolphin, Inia geoffrensis.

    Science.gov (United States)

    Mukhametov, L M

    1987-08-18

    An electroencephalographic study of sleep in Amazonian dolphins, Inia geoffrensis, revealed that unihemispheric slow-wave sleep is the dominant sleep type in this species, as in the other two dolphin species that were studied earlier.

  4. Propagation of Long-Wavelength Nonlinear Slow Sausage Waves in Stratified Magnetic Flux Tubes

    Science.gov (United States)

    Barbulescu, M.; Erdélyi, R.

    2016-05-01

    The propagation of nonlinear, long-wavelength, slow sausage waves in an expanding magnetic flux tube, embedded in a non-magnetic stratified environment, is discussed. The governing equation for surface waves, which is akin to the Leibovich-Roberts equation, is derived using the method of multiple scales. The solitary wave solution of the equation is obtained numerically. The results obtained are illustrative of a solitary wave whose properties are highly dependent on the degree of stratification.

  5. Stick-slip at soft adhesive interfaces mediated by slow frictional waves.

    Science.gov (United States)

    Viswanathan, Koushik; Sundaram, Narayan K; Chandrasekar, Srinivasan

    2016-06-28

    Stick-slip is a friction instability that governs diverse phenomena from squealing automobile brakes to earthquakes. At soft adhesive interfaces, this instability has long been attributed to Schallamach waves, which are a type of slow frictional wave. We use a contact configuration capable of isolating single wave events, coupled with high speed in situ imaging, to demonstrate the existence of two new stick-slip modes. It is shown that these modes also correspond to the passage of slow waves-separation pulse and slip pulse-with distinct nucleation and propagation characteristics. The slip pulse, characterized by a sharp stress front, propagates in the same direction as the Schallamach wave. In contrast, the separation pulse, involving local interface detachment and resembling a tensile neck, travels in exactly the opposite direction. A change in the stick-slip mode from the separation to the slip pulse is effected simply by increasing the normal force. Taken together, the three waves constitute all possible stick-slip modes in low-velocity sliding. The detailed observations enable us to present a phase diagram delineating the domains of occurrence of these waves. We suggest a direct analogy between the observed slow frictional waves and well known muscular locomotory waves in soft bodied organisms. Our work answers basic questions about adhesive mechanisms of frictional instabilities in natural and engineered systems, with broader implications for slow surface wave phenomena.

  6. Microfabrication of diamond-based slow-wave circuits for mm-wave and THz vacuum electronic sources

    Science.gov (United States)

    Lueck, M. R.; Malta, D. M.; Gilchrist, K. H.; Kory, C. L.; Mearini, G. T.; Dayton, J. A.

    2011-06-01

    Planar and helical slow-wave circuits for THz radiation sources have been made using novel microfabrication and assembly methods. A biplanar slow-wave circuit for a 650 GHz backward wave oscillator (BWO) was fabricated through the growth of diamond into high aspect ratio silicon molds and the selective metallization of the tops and sidewalls of 90 µm tall diamond features using lithographically created shadow masks. Helical slow-wave circuits for a 650 GHz BWO and a 95 GHz traveling wave tube were created through the patterning of trenches in thin film diamond, electroplating of gold half-helices, and high accuracy bonding of helix halves. The development of new techniques for the microfabrication of vacuum electronic components will help to facilitate compact and high-power sources for terahertz range radiation.

  7. Slow Waves in Fractures Filled with Viscous Fluid

    Energy Technology Data Exchange (ETDEWEB)

    Korneev, Valeri

    2008-01-08

    Stoneley guided waves in a fluid-filled fracture generally have larger amplitudes than other waves, and therefore, their properties need to be incorporated in more realistic models. In this study, a fracture is modeled as an infinite layer of viscous fluid bounded by two elastic half-spaces with identical parameters. For small fracture thickness, I obtain a simple dispersion equation for wave-propagation velocity. This velocity is much smaller than the velocity of a fluid wave in a Biot-type solution, in which fracture walls are assumed to be rigid. At seismic prospecting frequencies and realistic fracture thicknesses, the Stoneley guided wave has wavelengths on the order of several meters and an attenuation Q factor exceeding 10, which indicates the possibility of resonance excitation in fluid-bearing rocks. The velocity and attenuation of Stoneley guided waves are distinctly different at low frequencies for water and oil. The predominant role of fractures in fluid flow at field scales is supported by permeability data showing an increase of several orders of magnitude when compared to values obtained at laboratory scales. These data suggest that Stoneley guided waves should be taken into account in theories describing seismic wave propagation in fluid-saturated rocks.

  8. Linear analysis of a backward wave oscillator with triangular corrugated slow wave structure

    Science.gov (United States)

    Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul

    2016-05-01

    In this work, a backward wave oscillator (BWO) with triangularly corrugated periodic metallic slow wave structure (TrCSWS) driven by an infinitely thin annular electron beam is studied using linear theory. The electron beam is assumed to be guided by a strong magnetic field. The triangular axial profile of the SWS is approximated by a Fourier series in order to apply the linear Rayleigh-Fourier (R-F) theory that has long been used in the theoretical analysis of BWOs with sinusoidally corrugated SWS (SCSWS). The dispersion equation for various beam parameters has been solved and the temporal growth rate (TGR) of the electromagnetic wave for the fundamental TM_{01} mode is calculated numerically. The TGR values for different beam parameters have been compared with those of the BWO with SCSWS, semi-circularly corrugated SWS (SCCSWS) and trapezoidally corrugated SWS (TCSWS). In order to compare the TGR values, the amplitude of corrugation of the TrCSWS is varied so that its dispersion curve of TM_{01} mode almost coincides with that of the SCSWS and TCSWS. The study reveals that the performance (in terms of TGR) of the proposed BWO with TrCSWS is comparable to that of other BWOs with SCSWS and TCSWS for the same set of beam parameters and it provides significantly better performance than SCCSWS. So, the proposed TrCSWS that can easily be constructed may replace SCSWS, SCCSWS or TCSWS as their viable alternative.

  9. Grating-assisted superresolution of slow waves in Fourier space

    DEFF Research Database (Denmark)

    Thomas, N. Le; Houdré, R.; Frandsen, Lars Hagedorn

    2007-01-01

    with a high numerical aperture Fourier space imaging set-up. A high-resolution spectroscopy of the far-field emission diagram allows us to accurately and efficiently determine the dispersion curve and the group-index dispersion of planar photonic waveguides operating in the slow light regime....

  10. Interstitial cells of cajal generate electrical slow waves in the murine stomach.

    Science.gov (United States)

    Ordög, T; Ward, S M; Sanders, K M

    1999-07-01

    1. The gastric corpus and antrum contain interstitial cells of Cajal (ICC) within the tunica muscularis. We tested the hypothesis that ICC are involved in the generation and regeneration of electrical slow waves. 2. Normal, postnatal development of slow wave activity was characterized in tissues freshly removed from animals between birth and day 50 (D50). Slow wave amplitude and frequency increased during this period. Networks of myenteric ICC (IC-MY) were present in gastric muscles at birth and did not change significantly in appearance during the period of study as imaged by confocal immunofluorescence microscopy. 3. IC-MY networks were maintained and electrical rhythmicity developed in organ culture in a manner similar to normal postnatal development. Electrical activity was maintained for at least 48 days in culture. 4. Addition of a neutralizing antibody (ACK2) for the receptor tyrosine kinase, Kit, to the culture media caused progressive loss of Kit-immunoreactive cells. Loss of Kit-immunoreactive cells was associated with loss of slow wave activity. Most muscles became electrically quiescent after 3-4 weeks of exposure to ACK2. 5. In some muscles small clusters of Kit-immunoreactive IC-MY remained after culturing with ACK2. These muscles displayed slow wave activity but only in the immediate regions in which Kit-positive IC-MY remained. These data suggest that regions without Kit-immunoreactive cells cannot generate or regenerate slow waves. 6. After loss of Kit-immunoreactive cells, the muscles could not be paced by direct electrical stimulation. Stimulation with acetylcholine also failed to elicit slow waves. The data suggest that the generation of slow waves is an exclusive property of IC-MY; smooth muscle cells may not express the ionic apparatus necessary for generation of these events. 7. We conclude that IC-MY are an essential element in the spontaneous rhythmic electrical and contractile activity of gastric muscles. This class of ICC appears to

  11. Standing Slow MHD Waves in Radiatively Cooling Coronal Loops

    CERN Document Server

    Al-Ghafri, Khalil Salim

    2015-01-01

    The standing slow magneto-acoustic oscillations in cooling coronal loops are investigated. There are two damping mechanisms which are considered to generate the standing acoustic modes in coronal magnetic loops namely thermal conduction and radiation. The background temperature is assumed to change temporally due to optically thin radiation. In particular, the background plasma is assumed to be radiatively cooling. The effects of cooling on longitudinal slow MHD modes is analytically evaluated by choosing a simple form of radiative function that ensures the temperature evolution of the background plasma due to radiation coincides with the observed cooling profile of coronal loops. The assumption of low-beta plasma leads to neglect the magnetic field perturbation and eventually reduces the MHD equations to a 1D system modelling longitudinal MHD oscillations in a cooling coronal loop. The cooling is assumed to occur on a characteristic time scale much larger than the oscillation period that subsequently enables...

  12. Ion Acceleration by the Radiation Pressure of Slow Electromagnetic Wave

    CERN Document Server

    Bulanov, S V; Kando, M; Pegoraro, F; Bulanov, S S; Geddes, C G R; Schroeder, C; Esarey, E; Leemans, W

    2012-01-01

    When the ions are accelerated by the radiation pressure of the laser pulse, their velocity can not exceed the laser group velocity, in the case when it is less than the speed of light in vacuum. This is demonstrated in two cases corresponding to the thin foil target irradiated by a high intensity laser light and to the hole boring by the laser pulse in the extended plasma accompanied by the collisionless shock wave formation. It is found that the beams of accelerated at the collisionless shock wave front ions are unstable against the Buneman-lke and the Weibel-like instabilities which result in the ion energy spectrum broadening.

  13. Bistability of Slow and Fast Traveling Waves in Fluid Mixtures

    CERN Document Server

    Hollinger, S; Lücke, M; Hollinger, St.

    1997-01-01

    The appearence of a new type of fast nonlinear traveling wave states in binary fluid convection with increasing Soret effect is elucidated and the parameter range of their bistability with the common slower ones is evaluated numerically. The bifurcation behavior and the significantly different spatiotemporal properties of the different wave states - e.g. frequency, flow structure, and concentration distribution - are determined and related to each other and to a convenient measure of their nonlinearity. This allows to derive a limit for the applicability of small amplitude expansions. Additionally an universal scaling behavior of frequencies and mixing properties is found. PACS: 47.20.-k, 47.10.+g, 47.20.Ky

  14. Standing Slow-Mode Waves in Hot Coronal Loops: Observations, Modeling, and Coronal Seismology

    CERN Document Server

    Wang, Tongjiang

    2010-01-01

    Strongly damped Doppler shift oscillations are observed frequently associated with flarelike events in hot coronal loops. In this paper, a review of the observed properties and the theoretical modeling is presented. Statistical measurements of physical parameters (period, decay time, and amplitude) have been obtained based on a large number of events observed by SOHO/SUMER and Yohkoh/BCS. Several pieces of evidence are found to support their interpretation in terms of the fundamental standing longitudinal slow mode. The high excitation rate of these oscillations in small- or micro-flares suggest that the slow mode waves are a natural response of the coronal plasma to impulsive heating in closed magnetic structure. The strong damping and the rapid excitation of the observed waves are two major aspects of the waves that are poorly understood, and are the main subject of theoretical modeling. The slow waves are found mainly damped by thermal conduction and viscosity in hot coronal loops. The mode coupling seems ...

  15. Towards Predicting the Added Resistance of Slow Ships in Waves

    DEFF Research Database (Denmark)

    Amini Afshar, Mostafa

    been implemented using the Overture framework for solving partial differential equations on overset, boundary-fitted grids. This library includes support for parallel processing and a variety of direct and iterative system solvers. The non-linear water water wave problem is linearised about two base...... validated against analytical solutions for simple exact geometries like a cylinder and a sphere. The solver is now ready to be exercised on real ship geometries....

  16. Hybrid single-beam reconstruction technique for slow and fast varying wave fields.

    Science.gov (United States)

    Falaggis, Konstantinos; Kozacki, Tomasz; Kujawinska, Malgorzata

    2015-06-01

    An iterative single-beam wave field reconstruction technique that employs both non-paraxial, wave propagation based and paraxial deterministic phase retrieval techniques is presented. This approach overcomes two major obstacles that exist in the current state of the art techniques: iterative methods do not reconstruct slowly varying wave fields due to slow convergence and stagnation, and deterministic methods have paraxial limits, making the reconstructions of quickly varying object features impossible. In this work, a hybrid approach is reported that uses paraxial wave field corrections within iterative phase retrieval solvers. This technique is suitable for cases ranging from slow to fast varying wave fields, and unlike the currently available methods, can also reconstruct measurement objects with different regions of both slowly and quickly varying object features. It is further shown that this technique gives a higher accuracy than current single-beam phase retrieval techniques, and in comparison to the iterative methods, has a higher convergence speed.

  17. Kinetic Simulation of Slow Magnetosonic Waves and Quasi-periodic Upflows in the Solar Corona

    CERN Document Server

    Ruan, Wenzhi; Zhang, Lei; Vocks, Christian; Marsch, Eckart; Tu, Chuanyi; Peter, Hardi; Wang, Linghua

    2016-01-01

    Quasi-periodic disturbances of emission-line parameters are frequently observed in the corona. These disturbances propagate upward along the magnetic field with speeds $\\sim100~\\rm{km~s}^{-1}$. This phenomenon has been interpreted as evidence of the propagation of slow magnetosonic waves or argued to be signature of the intermittent outflows superposed on the background plasmas. Here we aim to present a new "wave + flow" model to interpret these observations. In our scenario, the oscillatory motion is a slow mode wave, and the flow is associated with a beam created by the wave-particle interaction owing to Landau resonance. With the help of a Vlasov model, we simulate the propagation of the slow mode wave and the generation of the beam flow. We find that weak periodic beam flows can be generated owing to Landau resonance in the solar corona, and the phase with strongest blueward asymmetry is ahead of that with strongest blueshift by about 1/4 period. We also find that the slow wave damps to the level of 1/e a...

  18. Observation of four-wave mixing in slow-light silicon photonic crystal waveguides.

    Science.gov (United States)

    McMillan, James F; Yu, Mingbin; Kwong, Dim-Lee; Wong, Chee Wei

    2010-07-19

    Four-wave mixing is observed in a silicon W1 photonic crystal waveguide. The dispersion dependence of the idler conversion efficiency is measured and shown to be enhanced at wavelengths exhibiting slow group velocities. A 12-dB increase in the conversion efficiency is observed. Concurrently, a decrease in the conversion bandwidth is observed due to the increase in group velocity dispersion in the slow-light regime. The experimentally observed conversion efficiencies agree with the numerically modeled results.

  19. Observations of four-wave mixing in slow-light silicon photonic crystal waveguides

    CERN Document Server

    McMillan, James F; Kwong, Dim-Lee; Wong, Chee Wei

    2010-01-01

    Four-wave mixing is observed in a silicon W1 photonic crystal waveguide. The dispersion dependence of the idler conversion efficiency is measured and shown to be enhanced at wavelengths exhibiting slow group velocities. A 12-dB increase in the conversion efficiency is observed. Concurrently, a decrease in the conversion bandwidth is observed due to the increase in group velocity dispersion in the slow-light regime. The experimentally observed conversion efficiencies agree with the numerically modeled results.

  20. Analysis of Dielectric Loss in a Helix Slow-wave Structure

    Directory of Open Access Journals (Sweden)

    S. K. Datta

    2009-09-01

    Full Text Available Equivalent circuit analysis of a helix slow-wave structure was carried out and closed form expressions were derived for the shunt capacitance and shunt conductance per unit length of the transmission-line equivalent circuit of the structure. These equivalent circuit parameters were interpreted for the dielectric attenuation constant of the slow-wave structure. The analysis was computationally simple and showsed excellent agreement with published results. The analysis was furthered for predicting the dielectric loss in typical C-Ku band and Ka band helical slow-wave structures, and variation of dielectric loss with temperature.Defence Science Journal, 2009, 59(5, pp.549-552, DOI:http://dx.doi.org/10.14429/dsj.59.1558

  1. Exponentially slow traveling waves on a finite interval for Burgers' type equation

    Directory of Open Access Journals (Sweden)

    Pieter De Groen

    1998-11-01

    Full Text Available In this paper we study for small positive $epsilon$ the slow motion of the solution for evolution equations of Burgers' type with small diffusion, $$ u_t=epsilon u_{xx}+f(u,u_x,, quad u(x,0=u_0(x, quad u(pm 1,t=pm 1, $$ on the bounded spatial domain $[-1,1]$; $f$ is a smooth function satisfying $f(1>0, f(-1<0$ and $int_{-1}^{1}f(tdt=0$. The initial and boundary value problem~($star$ has a unique asymptotically stable equilibrium solution that attracts all solutions starting with continuous initial data $u_0$. On the infinite spatial domain ${mathbb R}$ the differential equation has slow speed traveling wave solutions generated by profiles that satisfy the boundary conditions of~($star$. As long as its zero stays inside the interval $[-1,1]$, such a traveling wave suitably describes the slow long term behaviour of the solution of ($star$ and its speed characterizes the local velocity of the slow motion with exponential precision. A solution that starts near a traveling wave moves in a small neighborhood of the traveling wave with exponentially slow velocity (measured as the speed of the unique zero during an exponentially long time interval $(0,T$. In this paper we give a unified treatment of the problem, using both Hilbert space and maximum principle methods, and we give rigorous proofs of convergence of the solution and of the asymptotic estimate of the velocity.

  2. Slow-light Airy wave packets and their active control via electromagnetically induced transparency

    CERN Document Server

    Hang, Chao

    2014-01-01

    We propose a scheme to generate (3+1)-dimensional slow-light Airy wave packets in a resonant $\\Lambda$-type three-level atomic gas via electromagnetically induced transparency. We show that in the absence of dispersion the Airy wave packets formed by a probe field consist of two Airy wave packets accelerated in transverse directions and a longitudinal Gaussian pulse with a constant propagating velocity lowered to $10^{-5}\\,c$ ($c$ is the light speed in vacuum). We also show that in the presence of dispersion it is possible to generate another type of slow-light Airy wave packets consisting of two Airy beams in transverse directions and an Airy wave packet in the longitudinal direction. In this case, the longitudinal velocity of the Airy wave packet can be further reduced during propagation. Additionally, we further show that the transverse accelerations (or bending) of the both types of slow-light Airy wave packets can be completely eliminated and the motional trajectories of them can be actively manipulated ...

  3. Variational analysis of the disc-loaded waveguide slow-wave structures

    Institute of Scientific and Technical Information of China (English)

    Li Jian-Qing; Mo Yuan-Long

    2005-01-01

    The variational method is applied to calculate the dispersion characteristics of disc-loaded waveguide slow-wave structures. The parameters describing the waveguide discontinuities in disc-loaded waveguide are calculated by the variational method. Then the dispersion characteristics of slow-wave structures are obtained using lossless microwave quadrupole theory. Good agreement was observed between results of the variational method and those of field matching method and high frequency structure simulator. In the case of broad band, results of the variational method are better than those of field matching method.

  4. Radio-Frequency Characteristics of a Printed Rectangular Helix Slow-Wave Structure

    Institute of Scientific and Technical Information of China (English)

    FU Cheng-Fang; WEI Yan-Yu; WANG Wen-Xiang; GONG Yu-Bin

    2008-01-01

    A new type of printed rectangular he/ix slow-wave structure (SWS) is investigated using the field-matching method and the electromagnetic integral equations at the boundaries. The radio-frequency characteristics including the dispersion equation and the coupling impedance for transverse antisymmetric (odd) modes of this structure are analysed. The numerical results agree well with the results obtained by the EM simulation software HFSS. It is shown that the dispersion of the rectangular helix circuit is weakened, the phase velocity is reduced after filling the dielectric materials in the rectangular helix SWS. As a planar slow-wave structure, this structure has potential applications in compact TWTs.

  5. Enhanced four-wave mixing in graphene-silicon slow-light photonic crystal waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hao, E-mail: hz2299@columbia.edu, E-mail: tg2342@columbia.edu, E-mail: cww2104@columbia.edu [College of Electronic Information, Sichuan University, Chengdu 610064 (China); Optical Nanostructures Laboratory, Columbia University, New York, New York 10027 (United States); Gu, Tingyi, E-mail: hz2299@columbia.edu, E-mail: tg2342@columbia.edu, E-mail: cww2104@columbia.edu; McMillan, James F.; Wong, Chee Wei, E-mail: hz2299@columbia.edu, E-mail: tg2342@columbia.edu, E-mail: cww2104@columbia.edu [Optical Nanostructures Laboratory, Columbia University, New York, New York 10027 (United States); Petrone, Nicholas; Zande, Arend van der; Hone, James C. [Mechanical Engineering, Columbia University, New York, New York 10027 (United States); Yu, Mingbin; Lo, Guoqiang; Kwong, Dim-Lee [The Institute of Microelectronics, Singapore 117685 (Singapore); Feng, Guoying [College of Electronic Information, Sichuan University, Chengdu 610064 (China); Zhou, Shouhuan [College of Electronic Information, Sichuan University, Chengdu 610064 (China); North China Research Institute of Electro-Optics, Beijing 100015 (China)

    2014-09-01

    We demonstrate the enhanced four-wave mixing of monolayer graphene on slow-light silicon photonic crystal waveguides. 200-μm interaction length, a four-wave mixing conversion efficiency of −23 dB is achieved in the graphene-silicon slow-light hybrid, with an enhanced 3-dB conversion bandwidth of about 17 nm. Our measurements match well with nonlinear coupled-mode theory simulations based on the measured waveguide dispersion, and provide an effective way for all-optical signal processing in chip-scale integrated optics.

  6. Cancellous bone fast and slow waves obtained with Bayesian probability theory correlate with porosity from computed tomography.

    Science.gov (United States)

    Hoffman, Joseph J; Nelson, Amber M; Holland, Mark R; Miller, James G

    2012-09-01

    A Bayesian probability theory approach for separating overlapping ultrasonic fast and slow waves in cancellous bone has been previously introduced. The goals of this study were to investigate whether the fast and slow waves obtained from Bayesian separation of an apparently single mode signal individually correlate with porosity and to isolate the fast and slow waves from medial-lateral insonification of the calcaneus. The Bayesian technique was applied to trabecular bone data from eight human calcanei insonified in the medial-lateral direction. The phase velocity, slope of attenuation (nBUA), and amplitude were determined for both the fast and slow waves. The porosity was assessed by micro-computed tomography (microCT) and ranged from 78.7% to 94.1%. The method successfully separated the fast and slow waves from medial-lateral insonification of the calcaneus. The phase velocity for both the fast and slow wave modes showed an inverse correlation with porosity (R(2) = 0.73 and R(2) = 0.86, respectively). The slope of attenuation for both wave modes also had a negative correlation with porosity (fast wave: R(2) = 0.73, slow wave: R(2) = 0.53). The fast wave amplitude decreased with increasing porosity (R(2) = 0.66). Conversely, the slow wave amplitude modestly increased with increasing porosity (R(2) = 0.39).

  7. Study of the double rectangular waveguide grating slow-wave structure

    Institute of Scientific and Technical Information of China (English)

    Lu Zhi-Gang; Gong Yu-Bin; Wei Yan-Yu; Wang Wen-Xiang

    2006-01-01

    A slow-wave structure (SWS) with two opposite gratings inside a rectangular waveguide is presented and analysed. As an all-metal slow-wave circuit, this structure is especially suited for use in millimetre-wave travelling wave tubes (TWTs) due to its advantages of large size, high manufacturing precision and good heat dissipation. The first part of this paper concerns the wave properties of this structure in vacuum. The influence of the geometrical dimensions on dispersion characteristics and coupling impedance is investigated. The theoretical results show that this structure has a very strong dispersion and the coupling impedance for the fundamental wave is several tens of ohms, but the coupling impedance for -1 space harmonic wave is much lower than that for the fundamental wave, so the risk of backward wave oscillation is reduced. Besides these, the CST microwave studio is also used to simulate the dispersion property of the SWS. The simulation results from CST and the theoretical results agree well with each other, which supports the theory. In the second part, a small-signal analysis of a double rectangular waveguide grating TWT is presented. The typical small-signal gain per period is about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4%.

  8. Destabilization of long-wavelength Love and Stoneley waves in slow sliding

    CERN Document Server

    Ranjith, K

    2008-01-01

    Love waves are dispersive interfacial waves that are a mode of response for anti-plane motions of an elastic layer bonded to an elastic half-space. Similarly, Stoneley waves are interfacial waves in bonded contact of dissimilar elastic half-spaces, when the displacements are in the plane of the solids. It is shown that in slow sliding, long wavelength Love and Stoneley waves are destabilized by friction. Friction is assumed to have a positive instantaneous logarithmic dependence on slip rate and a logarithmic rate weakening behavior at steady-state. Long wavelength instabilities occur generically in sliding with rate- and state-dependent friction, even when an interfacial wave does not exist. For slip at low rates, such instabilities are quasi-static in nature, i.e., the phase velocity is negligibly small in comparison to a shear wave speed. The existence of an interfacial wave in bonded contact permits an instability to propagate with a speed of the order of a shear wave speed even in slow sliding, indicatin...

  9. Shock Formation and Energy Dissipation of Slow Magnetosonic Waves in Coronal Plumes

    Science.gov (United States)

    Cuntz, M.; Suess, S. T.

    2003-01-01

    We study the shock formation and energy dissipation of slow magnetosonic waves in coronal plumes. The wave parameters and the spreading function of the plumes as well as the base magnetic field strength are given by empirical constraints mostly from SOHO/UVCS. Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 bun, depending on the model parameters. In addition, following analytical estimates, we show that scale height of energy dissipation by the shocks ranges between 0.15 and 0.45 Rsun. This implies that shock heating by slow magnetosonic waves is relevant at most heights, even though this type of waves is apparently not a solely operating energy supply mechanism.

  10. Linear Analysis of Folded Double-Ridged Waveguide Slow-Wave Structure for Millimeter Wave Traveling Wave Tube

    Institute of Scientific and Technical Information of China (English)

    HE Jun; WEI Yan-Yu; GONG Yu-Bin; WANG Wen-Xiang

    2009-01-01

    A novel slow-wave structure (SWS), the folded double-ridged waveguide structure, is presented and its linear gain properties are investigated. The perturbed dispersion equation is derived and the small signal growth rate is calculated for dimensions of the ridge-loaded region and the parameters of the electron beam. The novel structure has potential applications in the production of high power and broad band radiation. For a cold beam, the linear theory predicts a gain of 1.1-1.27dB/period and a 3-dB small-signal gain bandwidth of 30% in W-band. A comparison between the folded double-ridged waveguide SWS and folded waveguide SWS (FWSWS) shows that with the same physical parameters, the novel SWS has an advantage over the FWSWS on the bandwidth and electron efficiency.

  11. Dynamic analysis of the conditional oscillator underlying slow waves in thalamocortical neurons

    Directory of Open Access Journals (Sweden)

    Francois eDavid

    2016-02-01

    Full Text Available During non-REM sleep the EEG shows characteristics waves that are generated by the dynamic interactions between cortical and thalamic oscillators. In thalamic neurons, low-threshold T-type Ca2+ channels play a pivotal role in almost every type of neuronal oscillations, including slow (<1 Hz waves, sleep spindles and delta waves. The transient opening of T channels gives rise to the low threshold spikes (LTSs, and associated high frequency bursts of action potentials, that are characteristically present during sleep spindles and delta waves, whereas the persistent opening of a small fraction of T channels, (i.e. ITwindow is responsible for the membrane potential bistability underlying sleep slow oscillations. Surprisingly thalamocortical (TC neurons express a very high density of T channels that largely exceed the amount required to generate LTSs and therefore, to support certain, if not all, sleep oscillations. Here, to clarify the relationship between T current density and sleep oscillations, we systematically investigated the impact of the T conductance level on the intrinsic rhythmic activities generated in TC neurons, combining in vitro experiments and TC neuron simulation. Using bifurcation analysis, we provide insights into the dynamical processes taking place at the transition between slow and delta oscillations. Our results show that although stable delta oscillations can be evoked with minimal T conductance, the full range of slow oscillation patterns, including groups of delta oscillations separated by Up states (grouped-delta slow waves requires a high density of T channels. Moreover, high levels of T conductance ensure the robustness of different types of slow oscillations.

  12. Preliminary study of slow and fast ultrasonic waves using MR images of trabecular bone phantom

    Energy Technology Data Exchange (ETDEWEB)

    Solis-Najera, S. E., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Neria-Pérez, J. A., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx; Medina, L., E-mail: solisnajera@ciencias.unam.mx, E-mail: angel.perez@ciencias.unam.mx, E-mail: lucia.medina@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, México, DF 04510 (Mexico); Garipov, R., E-mail: ruslan.garipov@mrsolutions.co.uk [MR Solutions Ltd, Surrey (United Kingdom); Rodríguez, A. O., E-mail: arog@xanum.uam.mx [Departamento Ingeniería Eléctrica, Universidad Autónoma Metropolitana Iztapalapa, México, DF 09340 (Mexico)

    2014-11-07

    Cancellous bone is a complex tissue that performs physiological and biomechanical functions in all vertebrates. It is made up of trabeculae that, from a simplified structural viewpoint, can be considered as plates and beams in a hyperstatic structure that change with time leading to osteoporosis. Several methods has been developed to study the trabecular bone microstructure among them is the Biot’s model which predicts the existence of two longitudinal waves in porous media; the slow and the fast waves, that can be related to porosity of the media. This paper is focused on the experimental detection of the two Biot’s waves of a trabecular bone phantom, consisting of a trabecular network of inorganic hydroxyapatite. Experimental measurements of both waves were performed using through transmission ultrasound. Results had shown clearly that the propagation of two waves propagation is transversal to the trabecular alignment. Otherwise the waves are overlapped and a single wave seems to be propagated. To validate these results, magnetic resonance images were acquired to assess the trabecular direction, and to assure that the pulses correspond to the slow and fast waves. This approach offers a methodology for non-invasive studies of trabecular bones.

  13. Sleep spindle and slow wave frequency reflect motor skill performance in primary school-age children

    NARCIS (Netherlands)

    Astill, Rebecca G; Piantoni, Giovanni; Raymann, Roy J E M; Vis, Jose C; Coppens, Joris E; Walker, Matthew P; Stickgold, Robert; Van Der Werf, Ysbrand D; Van Someren, Eus J W

    2014-01-01

    Background and Aim: The role of sleep in the enhancement of motor skills has been studied extensively in adults. We aimed to determine involvement of sleep and characteristics of spindles and slow waves in a motor skill in children. Hypothesis: We hypothesized sleep-dependence of skill enhancement a

  14. Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

    DEFF Research Database (Denmark)

    Varga, Edina T; Terney, Daniella; Atkins, Mary D

    2011-01-01

    Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were ...

  15. Inhomogeneities in the propagation of the slow wave in the stomach.

    Science.gov (United States)

    Lammers, W J

    2015-10-01

    The propagation of the slow wave in the stomach and its role in inducing sweeping peristaltic contractions toward the pylorus, essential for a proper digestion and emptying, have been studied for many years. Irregularities in the timing or in the pattern of propagation of the slow wave have been known to induce various gastric malfunctions and, recently, several types of gastric dysrhythmias have been described which could lead to gastric contraction abnormalities. In this study, Du et al. have analyzed the disturbances caused by a simple transmural incision in a human stomach, performed to obtain a biopsy of the muscle, on the propagation pattern of the slow wave. In addition, they show that such an incision may by itself also induce new types of gastric dysrhythmias. These results are important in demonstrating that the function of the stomach can easily be disturbed by such procedures. This mini-review describes several ways in which inhomogeneities in propagation may affect the conduction pattern of the slow wave, including the genesis of several dysrhythmias, and what is currently known about their impact on gastric contraction and digestion.

  16. Landau-Kleffner Syndrome, Electrical Status Epilepticus in Slow Wave Sleep, and Language Regression in Children

    Science.gov (United States)

    McVicar, Kathryn A.; Shinnar, Shlomo

    2004-01-01

    The Landau-Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood-onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of…

  17. Evidence for differential human slow-wave activity regulation across the brain

    NARCIS (Netherlands)

    Zavada, Andrei; Strijkstra, Arjen M.; Boerema, Ate S.; Daan, Serge; Beersma, Domien G. M.

    2009-01-01

    The regulation of the timing of sleep is thought to be linked to the temporal dynamics of slow-wave activity [SWA, electroencephalogram (EEG) spectral power in the similar to 0.75-4.5 Hz range] in the cortical non-rapid eye movement (NREM) sleep EEG. In the two-process model of sleep regulation, SWA

  18. Minipig negative slow wave demonstrates target/nontarget differences in P300 paradigm

    DEFF Research Database (Denmark)

    Arnfred, Sidse Marie; Lind, Nanna Marie; Moustgaard, Anette Caroline;

    2003-01-01

    The negative slow wave (NSW) is a late component of the event-related potential (ERP) in man modulated like the P300 by the stimulus, the task, and the response demand. Aiming at the development of a minipig model of schizophrenia, we investigated scalp ERPs in an auditory P300 paradigm in six...

  19. Memory stabilization with targeted reactivation during human slow-wave sleep

    NARCIS (Netherlands)

    Dongen, E.V. van; Takashima, A.; Barth, M.; Zapp, J.; Schad, L.R.; Paller, K.A.; Fernandez, G.S.E.

    2012-01-01

    It is believed that neural representations of recent experiences become reactivated during sleep, and that this process serves to stabilize associated memories in long-term memory. Here, we initiated this reactivation process for specific memories during slow-wave sleep. Participants studied 50 obje

  20. Neuronal Networks in Children with Continuous Spikes and Waves during Slow Sleep

    Science.gov (United States)

    Siniatchkin, Michael; Groening, Kristina; Moehring, Jan; Moeller, Friederike; Boor, Rainer; Brodbeck, Verena; Michel, Christoph M.; Rodionov, Roman; Lemieux, Louis; Stephani, Ulrich

    2010-01-01

    Epileptic encephalopathy with continuous spikes and waves during slow sleep is an age-related disorder characterized by the presence of interictal epileptiform discharges during at least greater than 85% of sleep and cognitive deficits associated with this electroencephalography pattern. The pathophysiological mechanisms of continuous spikes and…

  1. Four-wave mixing in slow light engineered silicon photonic crystal waveguides.

    Science.gov (United States)

    Monat, C; Ebnali-Heidari, M; Grillet, C; Corcoran, B; Eggleton, B J; White, T P; O'Faolain, L; Li, J; Krauss, T F

    2010-10-25

    We experimentally investigate four-wave mixing (FWM) in short (80 μm) dispersion-engineered slow light silicon photonic crystal waveguides. The pump, probe and idler signals all lie in a 14 nm wide low dispersion region with a near-constant group velocity of c/30. We measure an instantaneous conversion efficiency of up to -9dB between the idler and the continuous-wave probe, with 1W peak pump power and 6 nm pump-probe detuning. This conversion efficiency is found to be considerably higher (>10 × ) than that of a Si nanowire with a group velocity ten times larger. In addition, we estimate the FWM bandwidth to be at least that of the flat band slow light window. These results, supported by numerical simulations, emphasize the importance of engineering the dispersion of PhC waveguides to exploit the slow light enhancement of FWM efficiency, even for short device lengths.

  2. Slow-wave oscillations in the craniosacral space: a hemoliquorodynamic concept of origination.

    Science.gov (United States)

    Moskalenko, Yu E; Kravchenko, T I; Vainshtein, G B; Halvorson, P; Feilding, A; Mandara, A; Panov, A A; Semernya, V N

    2009-05-01

    The mechanism of formation of rhythmic, slow-wave oscillations in the craniospinal cavity were studied. Synchronous bioimpedance traces were made of the head and lumbosacral part of the spine in five healthy young subjects at rest and during voluntary breath-holding; these reflect changes in the ratios of blood and CSF volumes in these parts of the craniospinal space. Computer amplitude-frequency and spectral analysis of the data (Macintosh G-4, Chart-5.2) demonstrated slow (6-12 cycles/min) and rapid (pulsatile) oscillations in different directions in the cranial and lumbosacral areas. These data suggested a hemoliquorodynamic hypothesis for the craniosacral rhythm. The pulsatile and slow-wave oscillations of cerebrovascular tone and intracranial pressure evidently initiate to-and-fro displacements of the CSF in the caudal direction. The associated tonic contractions of the musculature of the lumbar part of the spine and the mobility of the sacrum are detected manually as the craniosacral rhythm.

  3. Slow strain waves in blocky geological media from GPS and seismological observations on the Amurian plate

    Science.gov (United States)

    Bykov, Victor G.; Trofimenko, Sergey V.

    2016-12-01

    Based on the statistical analysis of spatiotemporal distribution of earthquake epicenters and perennial geodetic observation series, new evidence is obtained for the existence of slow strain waves in the Earth. The results of our investigation allow us to identify the dynamics of seismicity along the northern boundary of the Amurian plate as a wave process. Migration of epicenters of weak earthquakes (2 ≤  M ≤ 4) is initiated by the east-west propagation of a strain wave front at an average velocity of 1000 km yr-1. We have found a synchronous quasi-periodic variation of seismicity in equally spaced clusters with spatial periods of 3.5 and 7.26° comparable with the length of slow strain waves. The geodetic observations at GPS sites in proximity to local active faults show that in a number of cases, the GPS site coordinate seasonal variations exhibit a significant phase shift, whereas the time series of these GPS sites differ significantly from a sinusoid. Based on experimental observation data and the developed model of crustal block movement, we have shown that there is one possible interpretation for this fact that the trajectory of GPS station position disturbance is induced by migration of crustal deformation in the form of slow waves.

  4. Analysis of π-mode Stopband in an Asymmetric Millimeter-Wave Helical Slow-Wave Structure

    Science.gov (United States)

    Datta, S. K.; Kumar, Lalit; Basu, B. N.

    2008-11-01

    A simple closed form formula for the estimation of π-mode stopband in an azimuthally asymmetric helical slow-wave structure (SWS) was developed following coupled-mode analysis of multiple reflections of the degenerate space-harmonic modes from the support rod discontinuities. The method incorporates the effects of circuit loss, and accrues the accuracy of 3D electromagnetic analysis by allowing the use of dispersion characteristics obtainable from any standard electromagnetic modeling. The formula is simple and amenable to easy computation, even using a scientific calculator, and without resorting to exhaustive and time-intensive numerical computation, and at the same time, without sacrificing the accuracy in results. The analysis was benchmarked against published results and excellent agreement observed. The analysis was further used for demonstrating the stopband phenomenon for a typical millimeter-wave helical slow-wave structure. Compared to low frequency structures, the stopband phenomenon for a millimeter-wave structure was found to be more pronounced, and an interesting inference was drawn as to how asymmetry induced stopband might be made to advantage in combating π-mode instabilities in a millimeter-wave traveling-wave tube.

  5. A prospective study of levetiracetam efficacy in epileptic syndromes with continuous spikes-waves during slow sleep

    DEFF Research Database (Denmark)

    Atkins, Mary; Nikanorova, Marina

    2011-01-01

    To evaluate the add-on effect of levetiracetam (LEV) treatment on the EEG and clinical status of children with continuous spikes-waves during slow sleep (CSWS).......To evaluate the add-on effect of levetiracetam (LEV) treatment on the EEG and clinical status of children with continuous spikes-waves during slow sleep (CSWS)....

  6. Prolonged P-Wave and QT Dispersion in Children with Inflammatory Bowel Disease in Remission

    Science.gov (United States)

    Yılmaz, Nuh; Kutluk, Günsel; Dedeoğlu, Reyhan; Öztarhan, Kazım; Tulunoğlu, Aras; Şap, Fatih

    2017-01-01

    Objectives. Ulcerative colitis (UC) and Crohn's disease (CD) are chronic inflammatory bowel diseases (IBD) with unclear underlying aetiologies. Severe cardiac arrhythmias have been emphasised in a few studies on adult IBD patients. This study aimed to investigate the alteration of the P-wave and QT interval dispersion parameters to assess the risk of atrial conduction and ventricular repolarisation abnormalities in pediatric IBD patients. Patients and Methods. Thirty-six IBD patients in remission (UC: 20, CD: 16) aged 3–18 years and 36 age- and sex-matched control patients were enrolled in the study. Twelve-lead electrocardiograms were used to determine durations of P-wave, QT, and corrected QT (QTc) interval dispersion. Transthoracic echocardiograms and 24-hour rhythm Holter recordings were obtained for both groups. Results. The P-wave dispersion, QT dispersion, and QTc interval dispersion (Pdisp, QTdisp, and QTcdisp) were significantly longer in the patient group. The mean values of Pminimum, Pmaximum, and QTcminimum were significantly different between the two groups. The echocardiography and Holter monitoring results were not significantly different between the groups. Furthermore, no differences in these parameters were detected between the CD and UC groups. Conclusion. Results suggest that paediatric IBD patients may carry potential risks for serious atrial and ventricular arrhythmias over time even during remission.

  7. Surface wave inversion for a p-wave velocity profile: Estimation of the squared slowness gradient

    NARCIS (Netherlands)

    Ponomarenko, A.V.; Kashtan, B.M.; Troyan, V.N.; Mulder, W.A.

    2013-01-01

    Surface waves can be used to obtain a near-surface shear wave profile. The inverse problem is usually solved for the locally 1-D problem of a set of homogeneous horizontal elastic layers. The output is a set of shear velocity values for each layer in the profile. P-wave velocity profile can be estim

  8. In-situ measurement of permeability of a porous interface using the ultrasonic slow wave

    Science.gov (United States)

    Lin, Lin

    2011-12-01

    Porous materials are an important class of materials. They occur in natural substances such as oil or water bearing rocks, marine sediment, biological tissues (e.g. bones), granular materials and man made materials such as separation membranes, thermal insulators, ceramics and fuel cells. Porous materials have been used in many areas of applied science and engineering. Understanding of porous media plays an important role in areas such as experimental acoustics, geo-mechanics, geophysics, biophysics, material science. Among the number of parameters describing porous materials, the permeability is often the reason the porous structure is of interest. Permeability is a measurement of the ability of a porous material to transmit fluid. At an interface, permeability describes the flow of fluid into or out of a porous media Ultrasound has been widely used for flaw detection and material characterization. Studies show that there are three waves that exist in porous materials: the longitudinal and shear wave that exist in other solid materials and the slow longitudinal wave that only exists in porous materials. This slow longitudinal wave can only be generated and propagated above a critical frequency. Measuring the critical frequency provides information about the intrinsic permeability of a porous interface. This thesis presents a new technique developed for an in-situ permeability measurement using measurement of slow wave. In this work, an exact solution for the critical wave number for the slow wave has been developed and showed suitable for measuring the permeability of porous materials. A computer model of the reflection coefficient at the interface of fluid/porous media has been developed for the acoustic measurement. Ultrasonic experiments confirmed the sensitivity of this technique to changes in permeability and fluid viscosity. A flow cell test has been performed to show one potential industrial application of this technique by showing open pore and closed pore

  9. Self modulation of slow magnetosonic waves and turbulence generation in solar coronal loops

    Science.gov (United States)

    Sharma, R. P.; Sharma, Prachi; Yadav, Nitin

    2017-01-01

    A mechanism based on turbulence for solar coronal heating has been introduced in the present work. Turbulence is considered as an important tool for heating. In the present work, turbulence generation takes place due to the nonlinear interaction of the magnetohydrodynamic waves. Slow magnetosonic waves get localized due to the density perturbations, which are assumed to be present in the background. These perturbations are associated with the low frequency slow magnetosonic waves that are supposed to be propagating in the coronal environment. The dynamics of high (0.01 Hz) and low frequency (0.001 Hz) slow magnetosonic waves have been studied by the two-fluid model and simulate numerically with the pseudo-spectral method. The power law index having a value of nearly -5/3 is obtained, which represents Kolmogorov scaling before the first break point. Based on the fact that the energy flux calculated from the Kolmogorov scaling is sufficient to heat the coronal loops as mentioned in the literature, the proposed interaction can be considered a source for turbulence generation having Kolmogorov scaling.

  10. MODELING OF REFLECTIVE PROPAGATING SLOW-MODE WAVE IN A FLARING LOOP

    Energy Technology Data Exchange (ETDEWEB)

    Fang, X.; Yuan, D.; Van Doorsselaere, T.; Keppens, R.; Xia, C. [Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven (Belgium)

    2015-11-01

    Quasi-periodic propagating intensity disturbances have been observed in large coronal loops in extreme ultraviolet images over a decade, and are widely accepted to be slow magnetosonic waves. However, spectroscopic observations from Hinode/EIS revealed their association with persistent coronal upflows, making this interpretation debatable. We perform a 2.5D magnetohydrodynamic simulation to imitate the chromospheric evaporation and the following reflected patterns in a flare loop. Our model encompasses the corona, transition region, and chromosphere. We demonstrate that the quasi periodic propagating intensity variations captured by the synthesized Solar Dynamics Observatory/Atmospheric Imaging Assembly 131, 94 Å emission images match the previous observations well. With particle tracers in the simulation, we confirm that these quasi periodic propagating intensity variations consist of reflected slow mode waves and mass flows with an average speed of 310 km s{sup −1} in an 80 Mm length loop with an average temperature of 9 MK. With the synthesized Doppler shift velocity and intensity maps of the Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation Fe xix line emission, we confirm that these reflected slow mode waves are propagating waves.

  11. Acoustic waves in a Biot-type porous snow model: The fast slow wave in light snow

    CERN Document Server

    Sidler, Rolf

    2015-01-01

    Wave velocities, attenuation and reflection coefficients in snow can not be explained by the widely used elastic or viscoelastic models for wave propagation. Instead, Biot's model of wave propagation in porous materials should be used. However, the application of Biot's model is difficult due to the large property space of the underlying porous material. Here we use the properties of ice and air as well as empirical relationships to define the properties of snow as a function of porosity. This reduction allows to predict phase velocities and attenuation of the shear- and compressional-waves as functions of porosity or density. For light snow the peculiarity was found that the velocity of the compressional wave of the first kind is lower than the compressional wave of the second kind that is commonly referred to as the "slow" wave. The reversal of the velocities comes with an increase of attenuation for the first compressional wave. This is in line with the common observation that sound is strongly absorbed af...

  12. Identification of the Slow Wave of Small Bowel Myoelectrical Activity by Surface Recording

    Science.gov (United States)

    2007-11-02

    to the process of digestion [1]. However, the difficulties in gaining access to this portion of the digestive tract have prevented the development of...Cirugía General y Digestivo I. Hospital Universitario "La Fe", Valencia. SPAIN 3Departamento de Cirugía. Facultad de Medicina de Valencia. SPAIN Report

  13. A method of designing photonic crystal grating slow-wave circuit for Ribbon-Beam microwave travelling wave amplifiers

    Institute of Scientific and Technical Information of China (English)

    Yin Hai-Rong; Gong Yu-Bin; Wei Yan-Yu; Gong Hua-Rong; Yue Ling-Na; Lu Zhi-Gang; Huang Min-Zhi; Wang Wen-Xiang

    2007-01-01

    A method of designing a photonic crystal grating slow-wave circuit in which the cylinders of the 2D photonic crystals dot on a cross-sectional plane is established by calculating the band structures of the 2D photonic crystals, and the eigenfrequency of the equivalent waveguide grating. For calculating the band structures, the eigenvalue equations of the photonic crystals in the system of photonic crystal grating slow-wave circuit are derived in a special polarization mode. Two examples are taken to show the method. The design result is validated by the scattering parameters of the same circuit. The result indicates that there exists no photonic band gap if the metal gratings do not extend into the photonic crystals; the design of the circuit without the metal gratings extending into the photonic crystals is less flexible than that with the metal gratings extending into the photonic crystals.

  14. Evaluation of Some Slow-wave Vane Structures for Aminiature Traveling-wave Tube at 30 Ghz

    Science.gov (United States)

    Kavanagh, Frank; Ebihara, Ben; Wallett, Thomas M.; Dayton, James A., Jr.

    1994-01-01

    The dispersion characteristics of six vane type slow wave structures were experimentally measured near 1 GHz to determine applicability in an electrostatically focused 30 GHz miniature traveling wave tube (TWT). From the measured results, the trapezoidal vane structure appeared to be the most promising exhibiting an interaction impedance equal to 337.9 ohms at beta(L)/pi equal to 0.3. A 30 GHz trapezoidal vane structure with coupling irises was fabricated using electrical discharge machining (EDM). This structure, however, was too lossy for a short electrostatically focused tube, but several of the structures are amenable to a tube with permanent magnetic focusing.

  15. Single-unit activity in piriform cortex during slow-wave state is shaped by recent odor experience.

    Science.gov (United States)

    Wilson, Donald A

    2010-02-03

    Memory and its underlying neural plasticity play important roles in sensory discrimination and cortical pattern recognition in olfaction. Given the reported function of slow-wave sleep states in neocortical and hippocampal memory consolidation, we hypothesized that activity during slow-wave states within the piriform cortex may be shaped by recent olfactory experience. Rats were anesthetized with urethane and allowed to spontaneously shift between slow-wave and fast-wave states as recorded in local field potentials within the anterior piriform cortex. Single-unit activity of piriform cortical layer II/III neurons was recorded simultaneously. The results suggest that piriform cortical activity during slow-wave states is shaped by recent (several minutes) odor experience. The temporal structure of single-unit activity during slow waves was modified if the animal had been stimulated with an odor within the receptive field of that cell. If no odor had been delivered, the activity of the cell during slow-wave activity was stable across the two periods. The results demonstrate that piriform cortical activity during slow-wave state is shaped by recent odor experience, which could contribute to odor memory consolidation.

  16. Laser Generation of Surface Waves on Cylinder with a Slow Coating

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shi-Gong; HU Wen-Xiang

    2008-01-01

    @@ An analytical model of acoustic field excited by a pulsed-laser line source on a coated cylinder is presented.Surface wave dispersive behaviours for a cylinder with a slow coating are analysed and compared with that of a bare cylinder.Based on this analysis, the laser-generated transient response of the perturbed Rayleigh wave and the higher modes of steel cylinder with a zinc coating are calculated from the model using residue theory and FFT technique.The theoretical result from the superposed waveform of the perturbed Rayleigh wave and higher modes agree well with the waveform obtained in experiment.The results show that the model and numerical method provide a useful technique for quantitatively characterizing coating parameters of coated cylinder by the laser generated surface waves.

  17. Microwave Slow-Wave Structure and Phase-Compensation Technique for Microwave Power Divider

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2014-04-01

    Full Text Available In this paper, T-shaped electromagnetic bandgap is loaded on a coupled transmission line itself and its electric performance is studied. Results show that microwave slow-wave effect can be enhanced and therefore, size reduction of a transmission-line-based circuit is possible. However, the transmission-line-based circuits characterize varied phase responses against frequency, which becomes a disadvantage where constant phase response is required. Consequently, a phase-compensation technique is further presented and studied. For demonstration purpose, an 8-way coupled-line power divider with 22.5 degree phase shifts between adjacent output ports, based on the studied slow-wave structure and phase-compensation technique, is developed. Results show both compact circuit architecture and improved phase imbalance are realized, confirming the investigated circuit structures and analyzing methodologies.

  18. Four-wave mixing in slow light photonic crystal waveguides with very high group index.

    Science.gov (United States)

    Li, Juntao; O'Faolain, Liam; Krauss, Thomas F

    2012-07-30

    We report efficient four-wave mixing in dispersion engineered slow light silicon photonic crystal waveguides with a flat band group index of n(g) = 60. Using only 15 mW continuous wave coupled input power, we observe a conversion efficiency of -28 dB. This efficiency represents a 30 dB enhancement compared to a silicon nanowire of the same length. At higher powers, thermal redshifting due to linear absorption was found to detune the slow light regime preventing the expected improvement in efficiency. We then overcome this thermal limitation by using oxide-clad waveguides, which we demonstrate for group indices of ng = 30. Higher group indices may be achieved with oxide clad-waveguides, and we predict conversion efficiencies approaching -10 dB, which is equivalent to that already achieved in silicon nanowires but for a 50x shorter length.

  19. The slow-mode nature of compressible wave power in solar wind turbulence

    CERN Document Server

    Howes, G G; Klein, K G; Chen, C H K; Salem, C S; TenBarge, J M

    2011-01-01

    We use a large, statistical set of measurements from the Wind spacecraft at 1 AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to show that the compressible component of inertial range solar wind turbulence is primarily in the kinetic slow mode. The zero-lag cross correlation C(delta n, delta B_parallel) between proton density fluctuations delta n and the field-aligned (compressible) component of the magnetic field delta B_parallel is negative and close to -1. The typical dependence of C(delta n,delta B_parallel) on the ion plasma beta_i is consistent with a spectrum of compressible wave energy that is almost entirely in the kinetic slow mode. This has important implications for both the nature of the density fluctuation spectrum and for the cascade of kinetic turbulence to short wavelengths, favoring evolution to the kinetic Alfven wave mode rather than the (fast) whistler mode.

  20. Observations of Dissipation of Slow Magneto-acoustic Waves in Polar Coronal Hole

    CERN Document Server

    Gupta, G R

    2014-01-01

    We focus on polar coronal hole region to find any evidence of dissipation of propagating slow magneto-acoustic waves. We obtained time-distance and frequency-distance maps along plume structure in polar coronal hole. We also obtained Fourier power maps of polar coronal hole in different frequency ranges in 171 \\AA\\ and 193 \\AA\\ passbands. We performed intensity distribution statistics in time domain at several locations in polar coronal hole. We find presence of propagating slow magneto-acoustic waves having temperature dependent propagation speeds. The wavelet analysis and Fourier power maps of polar coronal hole show that low-frequency waves are travelling longer distances (longer detection length) as compared to high-frequency waves. We found two distinct dissipation length scales of wave amplitude decay at two different height ranges (between 0-10 Mm and 10-70 Mm) along the observed plume structure. Dissipation length obtained at higher height range show some frequency dependence. Individual Fourier power...

  1. Investigation of a wideband folded double-ridged waveguide slow-wave system

    Institute of Scientific and Technical Information of China (English)

    He Jun; Wei Yan-Yu; Gong Yu-Bin; Wang Wen-Xiang

    2011-01-01

    The folded double-ridged waveguide structure is presented and its properties used for wide-band traveling-wave tube are investigated. Expressions of dispersion characteristics, normalized phase velocity and interaction impedance of this structure are derived and numerically calculated. The calculated results using our theory agree well with those obtained by using the 3D electromagnetic simulation software HFSS. Influences of the ridge-loaded area and broad-wall dimensions on the high frequency characteristics of the novel slow-wave structure are discussed. It is shown that the folded double-ridged waveguide structure has a much wider relative passband than the folded waveguide slow-wave structure and a relative passband of 67% could be obtained, indicating that this structure can operate in broad-band frequency ranges of beam-wave interaction. The small signal gain property is investigated for ensuring the improvement of bandwidth. Meanwhile, with comparable dispersion characteristics, the transverse section dimension of this novel structure is much smaller than that of conventional one, which indicates an available way to reduce the weight of traveling-wave tube.

  2. Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

    DEFF Research Database (Denmark)

    Varga, Edina T; Terney, Daniella; Atkins, Mary D;

    2011-01-01

    Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were...... recruited. Cathodal tDCS and sham stimulation were applied to the epileptic focus, before sleep (1 mA; 20 min). Cathodal tDCS did not reduce the spike-index in any of the patients....

  3. Slow-Wave Characteristics of Elliptical Corrugated Waveguides with a Concentric Circular Hole

    Institute of Scientific and Technical Information of China (English)

    XU Jin; WANG Wen-Xiang; YUE Ling-Na; WEI Yan-Yu; GONG Yu-Bin

    2006-01-01

    We present the formulation of elliptical corrugated waveguides with a concentric circular hole using the fieldmatching method and the addition theorem for Mathieu functions. The dispersion equation and the mean interaction impedance of this structure are derived separately. The numerical results, which are generally based on the current approach, agree well with the results obtained by the commercial software package CST. As a slow-wave structure, this structure has potential applications in high power microwave amplifiers and possibly filtering structures.

  4. Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep.

    OpenAIRE

    Casey, Sarah; Solomons, Luke C.; Steier, Joerg Sebastian; Kabra, Neeraj; Burnside, Anna; Pengo, Martino F.; Moxham, John; Goldstein, Laura Hilary; Kopelman, Michael David

    2016-01-01

    Objective: It has been debated whether different stages in the human sleep cycle preferentially mediate the consolidation of explicit and implicit memories, or whether all of the stages in succession are necessary for optimal consolidation. Here we investigated whether the selective deprivation of slow wave sleep (SWS) or rapid eye movement (REM) sleep over an entire night would have a specific effect on consolidation in explicit and implicit memory tasks. Method: Participants completed a set...

  5. Low acetylcholine during slow-wave sleep is critical for declarative memory consolidation

    OpenAIRE

    Gais, Steffen; Born, Jan

    2004-01-01

    The neurotransmitter acetylcholine is considered essential for proper functioning of the hippocampus-dependent declarative memory system, and it represents a major neuropharmacological target for the treatment of memory deficits, such as those in Alzheimer's disease. During slow-wave sleep (SWS), however, declarative memory consolidation is particularly strong, while acetylcholine levels in the hippocampus drop to a minimum. Observations in rats led to the hypothesis that the low cholinergic ...

  6. Dispersion characteristics of a slow wave structure with a modified photonic band gap

    Institute of Scientific and Technical Information of China (English)

    Gao Xi; Yang Zi-Qiang; Cao Wei-Ping; Jiang Yan-Nan

    2011-01-01

    This paper studies the dispersion characteristics of a modified photonic band-gap slow-wave structure with an open boundary by simulation and experiment. A mode launcher with a wheel radiator and a coupling probe is presented to excite a pure TM01-like mode. The cold test and simulation results show that the TM01-like mode is effectively excited and no parasitic modes appear. The dispersion characteristics obtained from the cold test are in good agreement with the calculated results.

  7. Theory of slow light enhanced four-wave mixing in photonic crystal waveguides

    OpenAIRE

    Santagiustina M.; Someda C.G.; Vadala G.; Combrie S.; Rossi A.

    2010-01-01

    The equations for Four-Wave-Mixing in a Photonic Crystal waveguide are derived accurately. The dispersive nature of slow-light enhancement, the impact of Bloch mode reshaping in the nonlinear overlap integrals and the tensor nature of the third order polarization are therefore taken into account. Numerical calculations reveal substantial differences with simpler models, which increase with decreasing group velocity. We predict that the gain for a 1.3 mm long, unoptimized GaInP waveguide will ...

  8. On the Source of Propagating Slow Magneto-acoustic Waves in Sunspots

    OpenAIRE

    S. Krishna Prasad; Jess, D. B.; Khomenko, Elena

    2015-01-01

    Recent high-resolution observations of sunspot oscillations using simultaneously operated ground- and space-based telescopes reveal the intrinsic connection between different layers of the solar atmosphere. However, it is not clear whether these oscillations are externally driven or generated in-situ. We address this question by using observations of propagating slow magneto-acoustic waves along a coronal fan loop system. In addition to the generally observed decreases in oscillation amplitud...

  9. A model of slow wave propagation and entrainment along the stomach.

    Science.gov (United States)

    Buist, Martin L; Corrias, Alberto; Poh, Yong Cheng

    2010-09-01

    Interstitial cells of Cajal (ICC) isolated from different regions of the stomach generate spontaneous electrical slow wave activity at different frequencies, with cells from the proximal stomach pacing faster than their distal counterparts. However, in vivo there exists a uniform pacing frequency; slow waves propagate aborally from the proximal stomach and subsequently entrain distal tissues. Significant resting membrane potential (RMP) gradients also exist within the stomach whereby membrane polarization generally increases from the fundus to the antrum. Both of these factors play a major role in the macroscopic electrical behavior of the stomach and as such, any tissue or organ level model of gastric electrophysiology should ensure that these phenomena are properly described. This study details a dual-cable model of gastric electrical activity that incorporates biophysically detailed single-cell models of the two predominant cell types, the ICC and smooth muscle cells. Mechanisms for the entrainment of the intrinsic pacing frequency gradient and for the establishment of the RMP gradient are presented. The resulting construct is able to reproduce experimentally recorded slow wave activity and provides a platform on which our understanding of gastric electrical activity can advance.

  10. [Slow-wave fluctuations in craniosacral space: hemo-liquorodynamic conception of origin].

    Science.gov (United States)

    Moskalenko, Iu E; Kravchenko, T I; Baĭnshteĭn, G B; Khal'vorson, P; Feĭlding, A; Mandara, A; Panov, A A; Semernia, V N

    2008-04-01

    In the paper, the mechanism of forming of rhythmic slow-wave fluctuations in craniospinal cavity was investigated. In five young healthy persons, at rest and under voluntary respiration arrest test, the bioimpedansograms of head and lumbosacral part of vertebral column were synchronously registered as these recordings reflect the changes of relationships between blood/CSF volumes in cranial and lumbosacral regions, respectively. The recordings were subjected to frequency and spectral computer analysis (PC Macintosh G-4, Chart 5.2. software). The rapid (pulsatile) as well as slow and counter-directed waves (frequency 6-10 cycles/min) of these processes were revealed in cranial and lumbosacral regions. The data obtained suggest the CSF dynamic concept of origin of the craniosacral rhythm. The pulse and slow-frequency oscillations of the cerebral vessels tone initiate corresponding intracranial pressure waves, and the latter are the motivating forces for to-and-fro CSF shifts in caudal direction. This mechanism is accompanied by tonic contractions of lumbar muscles and sacrum movements, and it is manually perceptible as a craniosacral rhythm.

  11. Inverse problems in cancellous bone: estimation of the ultrasonic properties of fast and slow waves using Bayesian probability theory.

    Science.gov (United States)

    Anderson, Christian C; Bauer, Adam Q; Holland, Mark R; Pakula, Michal; Laugier, Pascal; Bretthorst, G Larry; Miller, James G

    2010-11-01

    Quantitative ultrasonic characterization of cancellous bone can be complicated by artifacts introduced by analyzing acquired data consisting of two propagating waves (a fast wave and a slow wave) as if only one wave were present. Recovering the ultrasonic properties of overlapping fast and slow waves could therefore lead to enhancement of bone quality assessment. The current study uses Bayesian probability theory to estimate phase velocity and normalized broadband ultrasonic attenuation (nBUA) parameters in a model of fast and slow wave propagation. Calculations are carried out using Markov chain Monte Carlo with simulated annealing to approximate the marginal posterior probability densities for parameters in the model. The technique is applied to simulated data, to data acquired on two phantoms capable of generating two waves in acquired signals, and to data acquired on a human femur condyle specimen. The models are in good agreement with both the simulated and experimental data, and the values of the estimated ultrasonic parameters fall within expected ranges.

  12. Comparative Study between Slow Shock Wave Lithotripsy and Fast Shock Wave Lithotripsy in the Management of Renal Stone

    Directory of Open Access Journals (Sweden)

    AKM Zamanul Islam Bhuiyan

    2013-01-01

    Full Text Available Background: Renal calculi are frequent causes of ureteric colic. Extracorporeal shock wave lithotripsy is the most common treatment of these stones. It uses focused sound waves to break up stones externally. Objective: To compare the efficiency of slow and fast delivery rate of shock waves on stone fragmentation and treatment outcome in patients with renal calculi. Materials and Methods: This prospective study was done in the department of Urology, National Institute of Kidney diseases and Urology, Sher-e-Bangla Nagar, Dhaka from July 2006 to June 2007. Total 90 patients were treated using the Storz Medical Modulith ® SLX lithotripter. Patients were divided into Group A, Group B and Group C – each group having 30 subjects. Group A was selected for extracorporeal shockwave lithotripsy (ESWL by 60 shock waves per minute, Group B by 90 shock waves per minute and Group C by 120 shock waves per minute. Results: Complete clearance of stone was observed in 24 patients in Group A and 13 patients in both Group B and Group C in first session. In Group A only 3 patients needed second session but in Group B and Group C, 12 and 8 patients needed second session. In Group A only one patient needed third session but third session was required for 3 patients in Group B and 5 patients in Group C for complete clearance of stone. In Group A, subsequent sessions were performed under spinal anesthesia and in Group B under sedation and analgesia (p>0.001. Mean number of sessions for full clearance of stones in group A was 1.37 ± 0.85, in Group B was 1.8 ± 0.887 and in Group C was 2.0 ± 1.083. Significant difference was observed in term of sessions among groups (p>0.05. In first follow-up, complete clearance of stones was seen in 24 patients in Group A and 13 in both Group B and Group C. In second follow-up, 3 patients in Group A, 12 in Group B and 8 in Group C showed complete clearance of stones. It was observed that rate of stone clearance was higher in Group A

  13. Evaluation of QT and P Wave Dispersion and Mean Platelet Volume among Inflammatory Bowel Disease Patients

    Directory of Open Access Journals (Sweden)

    Yuksel DOGAN, Aliye SOYLU, Gulay A. EREN, Sule POTUROGLU, Can DOLAPCIOGLU, Kenan SONMEZ, Habibe DUMAN, Isa SEVINDIR

    2011-01-01

    Full Text Available Background: In inflammatory bowel disease (IBD number of thromboembolic events are increased due to hypercoagulupathy and platelet activation. Increases in mean platelet volume (MPV can lead to platelet activation, this leads to thromboembolic events and can cause acute coronary syndromes. In IBD patients, QT-dispersion and P-wave dispersion are predictors of ventricular arrhythmias and atrial fibrilation; MPV is accepted as a risk factor for acute coronary syndromes, we aimed at evaluating the correlations of these with the duration of disease, its localization and activity.Methods: The study group consisted of 69 IBD (Ulcerative colitis n: 54, Crohn's Disease n:15 patients and the control group included 38 healthy individuals. Disease activity was evaluated both endoscopically and clinically. Patients with existing cardiac conditions, those using QT prolonging medications and having systemic diseases, anemia and electrolyte imbalances were excluded from the study. QT-dispersion, P-wave dispersion and MPV values of both groups were compared with disease activity, its localization, duration of disease and the antibiotics used.Results: The P-wave dispersion values of the study group were significantly higher than those of the control group. Duration of the disease was not associated with QT-dispersion, and MPV levels. QT-dispersion, P-wave dispersion, MPV and platelet count levels were similar between the active and in mild ulcerative colitis patients. QT-dispersion levels were similar between IBD patients and the control group. No difference was observed between P-wave dispersion, QT-dispersion and MPV values; with regards to disease duration, disease activity, and localization in the study group (p>0.05.Conclusions: P-wave dispersion which is accepted as a risk factor for the development of atrial fibirilation was found to be high in our IBD patients. This demonstrates us that the risk of developing atrial fibrillation may be high in patients

  14. Experimental observation of sub-terahertz backward-wave amplification in a multi-level microfabricated slow-wave circuit

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Chan-Wook, E-mail: cw.baik@samsung.com; Ahn, Ho Young; Kim, Yongsung; Lee, Jooho; Hong, Seogwoo; Lee, Sang Hun; Choi, Jun Hee; Kim, Sunil; Kim, Jong Min; Hwang, Sungwoo [Samsung Advanced Institute of Technology, Suwon 443-803 (Korea, Republic of); Jeon, So-Yeon; Yu, SeGi [Department of Physics, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Collins, George; Read, Michael E.; Lawrence Ives, R. [Calabazas Creek Research, Inc., San Mateo, California 94404-1010 (United States)

    2015-11-09

    In our earlier paper dealing with dispersion retrieval from ultra-deep, reactive-ion-etched, slow-wave circuits on silicon substrates, it was proposed that splitting high-aspect-ratio circuits into multilevels enabled precise characterization in sub-terahertz frequency regime. This achievement prompted us to investigate beam-wave interaction through a vacuum-sealed integration with a 15-kV, 85-mA, thermionic, electron gun. Our experimental study demonstrates sub-terahertz, backward-wave amplification driven by an external oscillator. The measured output shows a frequency downshift, as well as power amplification, from beam loading even with low beam perveance. This offers a promising opportunity for the development of terahertz radiation sources, based on silicon technologies.

  15. Sharp wave-associated synchronized inputs from the piriform cortex activate olfactory tubercle neurons during slow-wave sleep.

    Science.gov (United States)

    Narikiyo, Kimiya; Manabe, Hiroyuki; Mori, Kensaku

    2014-01-01

    During slow-wave sleep, anterior piriform cortex neurons show highly synchronized discharges that accompany olfactory cortex sharp waves (OC-SPWs). The OC-SPW-related synchronized activity of anterior piriform cortex neurons travel down to the olfactory bulb and is thought to be involved in the reorganization of bulbar neuronal circuitry. However, influences of the OC-SPW-related activity on other regions of the central olfactory system are still unknown. Olfactory tubercle is an area of OC and part of ventral striatum that plays a key role in reward-directed motivational behaviors. In this study, we show that in freely behaving rats, olfactory tubercle receives OC-SPW-associated synchronized inputs during slow-wave sleep. Local field potentials in the olfactory tubercle showed SPW-like activities that were in synchrony with OC-SPWs. Single-unit recordings showed that a subpopulation of olfactory tubercle neurons discharged in synchrony with OC-SPWs. Furthermore, correlation analysis of spike activity of anterior piriform cortex and olfactory tubercle neurons revealed that the discharges of anterior piriform cortex neurons tended to precede those of olfactory tubercle neurons. Current source density analysis in urethane-anesthetized rats indicated that the current sink of the OC-SPW-associated input was located in layer III of the olfactory tubercle. These results indicate that OC-SPW-associated synchronized discharges of piriform cortex neurons travel to the deep layer of the olfactory tubercle and drive discharges of olfactory tubercle neurons. The entrainment of olfactory tubercle neurons in the OC-SPWs suggests that OC-SPWs coordinate reorganization of neuronal circuitry across wide areas of the central olfactory system including olfactory tubercle during slow-wave sleep.

  16. Coronal Seismology of Flare-Excited Standing Slow-Mode Waves Observed by SDO/AIA

    Science.gov (United States)

    Wang, Tongjiang; Ofman, Leon; Davila, Joseph M.

    2016-05-01

    Flare-excited longitudinal intensity oscillations in hot flaring loops have been recently detected by SDO/AIA in 94 and 131 Å bandpasses. Based on the interpretation in terms of a slow-mode wave, quantitative evidence of thermal conduction suppression in hot (>9 MK) loops has been obtained for the first time from measurements of the polytropic index and phase shift between the temperature and density perturbations (Wang et al. 2015, ApJL, 811, L13). This result has significant implications in two aspects. One is that the thermal conduction suppression suggests the need of greatly enhanced compressive viscosity to interpret the observed strong wave damping. The other is that the conduction suppression provides a reasonable mechanism for explaining the long-duration events where the thermal plasma is sustained well beyond the duration of impulsive hard X-ray bursts in many flares, for a time much longer than expected by the classical Spitzer conductive cooling. In this study, we model the observed standing slow-mode wave in Wang et al. (2015) using a 1D nonlinear MHD code. With the seismology-derived transport coefficients for thermal conduction and compressive viscosity, we successfully simulate the oscillation period and damping time of the observed waves. Based on the parametric study of the effect of thermal conduction suppression and viscosity enhancement on the observables, we discuss the inversion scheme for determining the energy transport coefficients by coronal seismology.

  17. Non-WKB Models of the FIP Effect: The Role of Slow Mode Waves

    CERN Document Server

    Laming, J Martin

    2011-01-01

    A model for element abundance fractionation between the solar chromosphere and corona is further developed. The ponderomotive force due to Alfven waves propagating through, or reflecting from the chromosphere in solar conditions generally accelerates chromospheric ions, but not neutrals, into the corona. This gives rise to what has become known as the First Ionization Potential (FIP) Effect. We incorporate new physical processes into the model. The chromospheric ionization balance is improved, and the effect of different approximations is discussed. We also treat the parametric generation of slow mode waves by the parallel propagating Alfven waves. This is also an effect of the ponderomotive force, arising from the periodic variation of the magnetic pressure driving an acoustic mode, which adds to the background longitudinal pressure. This can have subtle effects on the fractionation, rendering it quasi-mass independent in the lower regions of the chromosphere. We also briefly discuss the change in the fracti...

  18. Is there a relation between EEG-slow waves and memory dysfunction in epilepsy? A critical appraisal.

    Directory of Open Access Journals (Sweden)

    Höller eYvonne

    2015-06-01

    Full Text Available Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms which result in peri-ictal slow wave activity as detected by the electroencephalogram could negatively affect memory processes.Slow waves (≤ 4 Hz can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity.In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal-neocortical interactions during slow wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic-clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline.This hypothesis can only be assessed in long term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. In contrast, short term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance.

  19. Is There a Relation between EEG-Slow Waves and Memory Dysfunction in Epilepsy? A Critical Appraisal.

    Science.gov (United States)

    Höller, Yvonne; Trinka, Eugen

    2015-01-01

    Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow-wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms, which result in peri-ictal slow-wave activity as detected by the electroencephalogram, could negatively affect memory processes. Slow waves (≤4 Hz) can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms, which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow-wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity. In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms, which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal-neocortical interactions during slow-wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic-clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline. This hypothesis can only be assessed in long-term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. By contrast, short-term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance.

  20. FORWARD MODELING OF PROPAGATING SLOW WAVES IN CORONAL LOOPS AND THEIR FREQUENCY-DEPENDENT DAMPING

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Sudip; Banerjee, Dipankar [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Magyar, Norbert; Yuan, Ding; Doorsselaere, Tom Van, E-mail: sudip@iiap.res.in [Center for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, bus 2400, B-3001, Leuven (Belgium)

    2016-03-20

    Propagating slow waves in coronal loops exhibit a damping that depends upon the frequency of the waves. In this study we aim to investigate the relationship of the damping length (L{sub d}) with the frequency of the propagating wave. We present a 3D coronal loop model with uniform density and temperature and investigate the frequency-dependent damping mechanism for the four chosen wave periods. We include the thermal conduction to damp the waves as they propagate through the loop. The numerical model output has been forward modeled to generate synthetic images of SDO/AIA 171 and 193 Å channels. The use of forward modeling, which incorporates the atomic emission properties into the intensity images, allows us to directly compare our results with the real observations. The results show that the damping lengths vary linearly with the periods. We also measure the contributions of the emission properties on the damping lengths by using density values from the simulation. In addition to that we have also calculated the theoretical dependence of L{sub d} with wave periods and showed that it is consistent with the results we obtained from the numerical modeling and earlier observations.

  1. Resting-state slow wave power, healthy aging and cognitive performance.

    Science.gov (United States)

    Vlahou, Eleni L; Thurm, Franka; Kolassa, Iris-Tatjana; Schlee, Winfried

    2014-05-29

    Cognitive functions and spontaneous neural activity show significant changes over the life-span, but the interrelations between age, cognition and resting-state brain oscillations are not well understood. Here, we assessed performance on the Trail Making Test and resting-state magnetoencephalographic (MEG) recordings from 53 healthy adults (18-89 years old) to investigate associations between age-dependent changes in spontaneous oscillatory activity and cognitive performance. Results show that healthy aging is accompanied by a marked and linear decrease of resting-state activity in the slow frequency range (0.5-6.5 Hz). The effects of slow wave power on cognitive performance were expressed as interactions with age: For older (>54 years), but not younger participants, enhanced delta and theta power in temporal and central regions was positively associated with perceptual speed and executive functioning. Consistent with previous work, these findings substantiate further the important role of slow wave oscillations in neurocognitive function during healthy aging.

  2. Metabolic component of the temperature-sensitivity of slow waves recorded from gastric muscle of the guinea-pig.

    Science.gov (United States)

    Nakamura, Eri; Kito, Yoshihiko; Hashitani, Hikaru; Suzuki, Hikaru

    2006-02-01

    The effects of changes in temperature on slow waves were investigated in smooth muscle tissues isolated from the guinea-pig gastric antrum. Within the range 24 degrees C to 42 degrees C, elevation of temperature increased the frequency and maximum rate of rise of the upstroke phase (dV/dt) of slow waves and decreased their duration, with no alteration to amplitude or resting membrane potential. These observations also applied to follower potentials and pacemaker potentials recorded from longitudinal muscle and myenteric interstitial cells, respectively. Slow waves were comprised of 1st and 2nd components, and the latency for generating the 2nd component was decreased exponentially by elevating temperature, reaching a stable value of about 1 s above 32 degrees C. The temperature coefficient was >2 for the frequency, dV/dt and latency of the 2nd component, about 1.7 for the duration and about 1 for amplitude. Potassium cyanide (KCN), an inhibitor of mitochondrial metabolic activity, reduced the frequency and duration of slow waves, with no alteration to other parameters (amplitude, dV/dt, latency). In the presence of 30 microM KCN, the temperature-dependency of the frequency of slow waves was diminished or abolished, while other parameters of slow waves remained unaltered. These results indicate that in slow waves the frequency may be related to metabolic activities, while the temperature-dependent changes in the dV/dt, latency for the 2nd component and duration of slow waves are produced largely by mechanisms other than metabolic activity.

  3. Dynamics of nonlinear resonant slow MHD waves in twisted flux tubes

    Directory of Open Access Journals (Sweden)

    R. Erdélyi

    2002-01-01

    Full Text Available Nonlinear resonant magnetohydrodynamic (MHD waves are studied in weakly dissipative isotropic plasmas in cylindrical geometry. This geometry is suitable and is needed when one intends to study resonant MHD waves in magnetic flux tubes (e.g. for sunspots, coronal loops, solar plumes, solar wind, the magnetosphere, etc. The resonant behaviour of slow MHD waves is confined in a narrow dissipative layer. Using the method of simplified matched asymptotic expansions inside and outside of the narrow dissipative layer, we generalise the so-called connection formulae obtained in linear MHD for the Eulerian perturbation of the total pressure and for the normal component of the velocity. These connection formulae for resonant MHD waves across the dissipative layer play a similar role as the well-known Rankine-Hugoniot relations connecting solutions at both sides of MHD shock waves. The key results are the nonlinear connection formulae found in dissipative cylindrical MHD which are an important extension of their counterparts obtained in linear ideal MHD (Sakurai et al., 1991, linear dissipative MHD (Goossens et al., 1995; Erdélyi, 1997 and in nonlinear dissipative MHD derived in slab geometry (Ruderman et al., 1997. These generalised connection formulae enable us to connect solutions obtained at both sides of the dissipative layer without solving the MHD equations in the dissipative layer possibly saving a considerable amount of CPU-time when solving the full nonlinear resonant MHD problem.

  4. STUDY ON RECTANGULAR WAVEGUIDE GRATING SLOW-WAVE STRUCTURE WITH COSINE-SHAPED GROOVES

    Institute of Scientific and Technical Information of China (English)

    Lu Zhigang; Wei Yanyu; Gong Yubin; Wu Zhoumiao; Wang Wenxiang

    2007-01-01

    This paper focuses on a new rectangular waveguide grating Slow-Wave Structure(SWS)with cosine-shaped grooves and studies the propagation characteristics of the wave in the SWS.By using the approximate field-matching conditions,the dispersion equation and the coupling impedance of this circuit are obtained.The dispersion curves and coupling impedances of the fundamental wave are calculated and the influences of the various geometrical dimensions are discussed.The results show that the bandwidth of the cosine-shaped groove SWS is much wider than that of rectangular-shaped groove one.And reducing the groove width can broaden the frequency-band and decrease the phase-velocity,while increment of the groove-depth can also decrease phase-velocity.For above cases,the coupling impedance is more than 16Ω.The present analysis will be helpful on further study and design of the RF systems used in millimeter wave Traveling Wave Tube(TWT).

  5. Two features of sleep slow waves: homeostatic and reactive aspects--from long term to instant sleep homeostasis.

    Science.gov (United States)

    Halász, Péter; Bódizs, Róbert; Parrino, Liborio; Terzano, Mario

    2014-10-01

    In this paper we reviewed results of sleep research that have changed the views about sleep slow wave homeostasis, which involve use-dependent and experience-dependent local aspects to understand more of the physiology of plastic changes during sleep. Apart from the traditional homeostatic slow-wave economy, we also overviewed research on the existence and role of reactive aspects of sleep slow waves. Based on the results from spontaneous and artificially evoked slow waves, we offer a new hypothesis on instant slow wave homeostatic regulation. This regulation compensates for any potentially sleep-disturbing events by providing instant "delta injections" to maintain the nightly delta level, thus protecting cognitive functions located in the frontal lobe. We suggest that this double (long-term /instant) homeostasis provides double security for the frontal lobes in order to protect cognitive functions. The incorporation of reactive slow wave activity (SWA) makes sleep regulation more dynamic and provides more room for the internalization of external influences during sleep.

  6. [Significance of intermittent slow waves with right posterior accentuation in the EEG's of psychiatric patients].

    Science.gov (United States)

    Ulrich, G; Otto, W

    1984-02-01

    The study was based on the frequent occurrence of intermittent slow waves right-posterior accentuation (IRP) in the EEGs of psychiatric patients. With regard to the EEG-phenomenon we present a detailed morphological and functional description as well as an evaluation from a developmental point of view. According to case histories a clinico-psychopathological characterization of the patients with IRP is given. The IRP-phenomenon can be interpreted electrogenetically against the background of and in connection with the so-called slow alpha variant rhythms as well as the posterior slow waves characteristic of children and adolescents. These patterns have in common a certain tendency to right-sided accentuation. In accord with a hypothesis (which has been derived from other observations and considerations) of a "maturation gradient" which favours the left hemisphere, we try to explain the IRP-phenomenon as an expression of a maturation deficit. Whereas the slow alpha variant rhythms and the posterior slow waves characteristic of children and adolescents appear bilaterally for the most part, IRP by definition, limited to the right hemisphere, may be considered as a less pronounced form in comparison. Deriving from clinico-psychopathological assessment the relationships are as follows: Patients with IRP account for about 5% of the in-patients in our psychiatric hospital. The IRP phenomenon seems to be closely linked to the male sex. Although a clear relationship with nosological categories (ICD) could not be proved, it seems that patients suffering from schizophrenic psychoses (ICD No. 295) are more frequently represented among the patients with the IRP-phenomenon than others. For the group of schizophrenic patients with IRP we found in contrast to a control group of schizophrenics without IRP a tendency to earlier onset of their disease. Compared with the control group it is found that the IRP groups consists of younger patients at the time of conducting this study. The

  7. Theory of slow light enhanced four-wave mixing in photonic crystal waveguides.

    Science.gov (United States)

    Santagiustina, M; Someda, C G; Vadalà, G; Combrié, S; De Rossi, A

    2010-09-27

    The equations for Four-Wave-Mixing in a Photonic Crystal waveguide are derived accurately. The dispersive nature of slow-light enhancement, the impact of Bloch mode reshaping in the nonlinear overlap integrals and the tensor nature of the third order polarization are therefore taken into account. Numerical calculations reveal substantial differences with simpler models, which increase with decreasing group velocity. We predict that the gain for a 1.3 mm long, unoptimized GaInP waveguide will exceed 10 dB if the pump power exceeds 1 W.

  8. Theory of Slow Light Enhanced Four-Wave Mixing in Photonic Crystal Waveguides

    CERN Document Server

    Santagiustina, M; Vadalà, G; Combrié, S; De Rossi, A

    2010-01-01

    The equations for Four-Wave-Mixing in a Photonic Crystal waveguide are derived accurately. The dispersive nature of slow-light enhancement, the impact of Bloch mode reshaping in the nonlinear overlap integrals and the tensor nature of the third order polarization are therefore taken into account. Numerical calculations reveal substantial differences with simpler models, which increase with decreasing group velocity. We predict that the gain for a 1.3 mm long, unoptimized GaInP waveguide will exceed 10 dB if the pump power exceeds 1 W.

  9. THE COUPLING IMPEDANCE OF VANE-LOADED TAPE HELIX SLOW-WAVE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Chen Qingyou; Wang Zicheng; Wu Hongshi

    2001-01-01

    Based on the actual vane-loaded tape helix slow wave structure, a new theoretical analytic model for calculating coupling impedance is proposed by Chen Qingyou, et al.(1999)with calculated values of dispersion in good agreement with measured ones. In this paper, it is continued to use this model to calculate the coupling impedance of such a structure, and analyze the effects of the propagation power within vane gaps and the helix gap on the coupling impedance.As a result, the theoretical values are found to be in good agreement with the measured ones,with the maximum difference less than ±18%.

  10. Excitation of a double corrugation slow-wave structure in terahertz range

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Krozer, Viktor; Kotiranta, Mikko;

    2011-01-01

    In spite of the fact that the technology is constantly advancing, the realization of terahertz components is still heavily constrained by problems arising from technological limitations. As a result, the design of terahertz components still remains a challenging problem. In this work, an excitation...... problem of a terahertz double corrugation slow-wave structure is considered and practical realization of the structure using currently available technological processes is discussed. The parameters of the realized excitation structure are optimized for vacuum electronics applications while taking...

  11. Using COMSOL Multiphysics Software to Model Anisotropic Dielectric and Metamaterial Effects in Folded-Waveguide Traveling-Wave Tube Slow-Wave Circuits

    Science.gov (United States)

    Starinshak, David P.; Smith, Nathan D.; Wilson, Jeffrey D.

    2008-01-01

    The electromagnetic effects of conventional dielectrics, anisotropic dielectrics, and metamaterials were modeled in a terahertz-frequency folded-waveguide slow-wave circuit. Results of attempts to utilize these materials to increase efficiency are presented.

  12. Optimization of relativistic backward wave oscillator with non-uniform slow wave structure and a resonant reflector

    Science.gov (United States)

    Chen, Zaigao; Wang, Jianguo; Wang, Yue

    2015-01-01

    This letter optimizes synchronously 18 parameters of a relativistic backward wave oscillator with non-uniform slow wave structure (SWS) and a resonant reflector by using the parallel genetic algorithms and particle-in-cell simulation. The optimization results show that the generation efficiency of microwave from the electron beam has increased 32% compared to that of the original device. After optimization, the electromagnetic mode propagating in the resonant changes from the original TM020 mode of reflector to higher-order TM021 mode, which has a high reflection coefficient in a broader frequency range than that of the former. The modulation of current inside the optimized device is much deeper than that in the original one. The product of the electric field and current is defined. Observing this product, it is found that the interaction of the electron beam with the electromagnetic wave in the optimized device is much stronger than that in the original device, and at the rear part of SWS of the optimized device, the electron beam dominantly gives out the energy to the electromagnetic wave, leading to the higher generation efficiency of microwave than that of the original device.

  13. Hybrid metal-dielectric, slow wave structure with magnetic coupling and compensation

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A.V., E-mail: asmirnov@radiabeam.com [RadiaBeam Systems LLC, 1713 Stewart St., Santa Monica, CA 90404 (United States); Savin, E. [RadiaBeam Systems LLC, 1713 Stewart St., Santa Monica, CA 90404 (United States); National Research Nuclear University “MEPhI”, Moscow 115409 (Russian Federation)

    2016-06-01

    A number of electron beam vacuum devices such as small radiofrequency (RF) linear accelerators (linacs) and microwave traveling wave tubes (TWTs) utilize slow wave structures which are usually rather complicated in production and may require multi-step brazing and time consuming tuning. Fabrication of these devices becomes challenging at centimeter wavelengths, at large number of cells, and when a series or mass production of such structures is required. A hybrid, metal-dielectric, periodic structure for low gradient, low beam current applications is introduced here as a modification of Andreev’s disk-and-washer (DaW) structure. Compensated type of coupling between even and odd TE01 modes in the novel structure results in negative group velocity with absolute values as high as 0.1c–0.2c demonstrated in simulations. Sensitivity to material imperfections and electrodynamic parameters of the disk-and-ring (DaR) structure are considered numerically using a single cell model.

  14. Properties of short-wavelength oblique Alfvén and slow waves

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J. S.; Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Voitenko, Y. [Solar-Terrestrial Centre of Excellence, Space Physics Division, Belgian Institute for Space Aeronomy, Avenue Circulaire 3, B-1180 Brussels (Belgium); Yu, M. Y. [Institute for Fusion Theory and Simulation and Department of Physics, Zhejiang University, Hangzhou 310027 (China); Lu, J. Y., E-mail: jszhao@pmo.ac.cn [College of Math and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2014-10-01

    Linear properties of kinetic Alfvén waves (KAWs) and kinetic slow waves (KSWs) are studied in the framework of two-fluid magnetohydrodynamics. We obtain the wave dispersion relations that are valid in a wide range of the wave frequency ω and plasma-to-magnetic pressure ratio β. The KAW frequency can reach and exceed the ion-cyclotron frequency at ion kinetic scales, whereas the KSW frequency remains sub-cyclotron. At β ∼ 1, the plasma and magnetic pressure perturbations of both modes are in anti-phase, so that there is nearly no total pressure perturbations. However, these modes also exhibit several opposite properties. At high β, the electric polarization ratios of KAWs and KSWs are opposite at the ion gyroradius scale, where KAWs are polarized in the sense of electron gyration (right-hand polarized) and KSWs are left-hand polarized. The magnetic helicity σ ∼ 1 for KAWs and σ ∼ –1 for KSWs, and the ion Alfvén ratio R{sub Ai} << 1 for KAWs and R{sub Ai} >> 1 for KSWs. We also found transition wavenumbers where KAWs change their polarization from left-handed to right-handed. These new properties can be used to discriminate KAWs and KSWs when interpreting kinetic-scale electromagnetic fluctuations observed in various solar-terrestrial plasmas. This concerns, in particular, identification of modes responsible for kinetic-scale pressure-balanced fluctuations and turbulence in the solar wind.

  15. Age-Dependency of Location of Epileptic Foci in "Continuous Spike-and-Waves during Sleep": A Parallel to the Posterior-Anterior Trajectory of Slow Wave Activity.

    Science.gov (United States)

    Heinzle, Bigna Katrin Bölsterli; Bast, Thomas; Critelli, Hanne; Huber, Reto; Schmitt, Bernhard

    2017-02-01

    Background Epileptic encephalopathy with continuous spike-and-waves during sleep (CSWS) occurs during childhood and is characterized by an activation of spike wave complexes during slow wave sleep. The location of epileptic foci is variable, as is etiology. A relationship between the epileptic focus and age has been shown in various focal epilepsies following a posterior-anterior trajectory, and a link to brain maturation has been proposed.We hypothesize that in CSWS, maximal spike wave activity, corresponding to the epileptic focus, is related to age and shows a posterior-anterior evolution. Findings In a retrospective cross-sectional study on CSWS (22 EEGs of 22 patients aged 3.1-13.5 years), the location of the epileptic focus is related to age and follows a posterior-anterior course. Younger patients are more likely to have posterior foci than older ones. Conclusions We propose that the posterior-anterior trajectory of maximal spike waves in CSWS might reflect maturational changes of maximal expression of sleep slow waves, which follow a comparable course. Epileptic spike waves, that is, "hyper-synchronized slow waves" may occur at the place where the highest and therefore most synchronized slow waves meet brain tissue with an increased susceptibility to synchronization.

  16. Resonant Absorption of Fast Magnetoacoustic Waves due to Coupling into the Slow and Alfven Continua in the Solar Atmosphere

    CERN Document Server

    Clack, C T M; Douglas, M

    2010-01-01

    Resonant absorption of fast magnetoacoustic (FMA) waves in an inhomogeneous, weakly dissipative, one-dimensional planar, strongly anisotropic and dispersive plasma is investigated. The magnetic configuration consists of an inhomogeneous magnetic slab sandwiched between two regions of semi-infinite homogeneous magnetic plasmas. Laterally driven FMA waves penetrate the inhomogeneous slab interacting with the localised slow or Alfven waves present in the inhomogeneous layer and are partly reflected, dissipated and transmitted by this region. The presented research aims to find the coefficient of wave energy absorption under solar chromospheric and coronal conditions. Numerical results are analyzed to find the coefficient of wave energy absorption at both the slow and Alfven resonance positions. The mathematical derivations are based on the two simplifying assumptions that (i) nonlinearity is weak, and (ii) the thickness of the inhomogeneous layer is small in comparison to the wavelength of the wave, i.e. we empl...

  17. Stimulating forebrain communications: Slow sinusoidal electric fields over frontal cortices dynamically modulate hippocampal activity and cortico-hippocampal interplay during slow-wave states.

    Science.gov (United States)

    Greenberg, Anastasia; Whitten, Tara A; Dickson, Clayton T

    2016-06-01

    Slow-wave states are characterized by the most global physiological phenomenon in the mammalian brain, the large-amplitude slow oscillation (SO; ~1Hz) composed of alternating states of activity (ON/UP states) and silence (OFF/DOWN states) at the network and single cell levels. The SO is cortically generated and appears as a traveling wave that can propagate across the cortical surface and can invade the hippocampus. This cortical rhythm is thought to be imperative for sleep-dependent memory consolidation, potentially through increased interactions with the hippocampus. The SO is correlated with learning and its presumed enhancement via slow rhythmic electrical field stimulation improves subsequent mnemonic performance. However, the mechanism by which such field stimulation influences the dynamics of ongoing cortico-hippocampal communication is unknown. Here we show - using multi-site recordings in urethane-anesthetized rats - that sinusoidal electrical field stimulation applied to the frontal region of the cerebral cortex creates a platform for improved cortico-hippocampal communication. Moderate-intensity field stimulation entrained hippocampal slow activity (likely by way of the temporoammonic pathway) and also increased sharp-wave ripples, the signature memory replay events of the hippocampus, and further increased cortical spindles. Following cessation of high-intensity stimulation, SO interactions in the cortical-to-hippocampal direction were reduced, while the reversed hippocampal-to-cortical communication at both SO and gamma bandwidths was enhanced. Taken together, these findings suggest that cortical field stimulation may function to boost memory consolidation by strengthening cortico-hippocampal and hippocampo-cortical interplay at multiple nested frequencies in an intensity-dependent fashion.

  18. Experimental observation of ultrasound fast and slow waves through three-dimensional printed trabecular bone phantoms.

    Science.gov (United States)

    Mézière, F; Juskova, P; Woittequand, J; Muller, M; Bossy, E; Boistel, Renaud; Malaquin, L; Derode, A

    2016-02-01

    In this paper, ultrasound measurements of 1:1 scale three-dimensional (3D) printed trabecular bone phantoms are reported. The micro-structure of a trabecular horse bone sample was obtained via synchrotron x-ray microtomography, converted to a 3D binary data set, and successfully 3D-printed at scale 1:1. Ultrasound through-transmission experiments were also performed through a highly anisotropic version of this structure, obtained by elongating the digitized structure prior to 3D printing. As in real anisotropic trabecular bone, both the fast and slow waves were observed. This illustrates the potential of stereolithography and the relevance of such bone phantoms for the study of ultrasound propagation in bone.

  19. Giant Amplification in Degenerate Band Edge Slow-Wave Structures Interacting with an Electron Beam

    CERN Document Server

    Othman, Mohamed A K; Figotin, Alexander; Capolino, Filippo

    2015-01-01

    We advance here a new amplification regime based on synchronous operation of four degenerate electromagnetic (EM) modes and the electron beam referred to as super synchronization. These four EM modes arise in a Fabry-Perot cavity (FPC) when degenerate band edge (DBE) condition is satisfied. The modes interact constructively with the electron beam resulting in superior amplification. In particular, much larger gains are achieved for smaller beam currents compared to conventional structures allowing for synchronization with only a single EM mode. We construct a mutli transmission line (MTL) model for a loaded waveguide slow-wave structure exhibiting a DBE, and investigate the phenomenon of giant gain via super synchronization using generalized Pierce model.

  20. 1.5 octave wideband traveling-wave tube with heavily-loaded helical slow-wave structure

    CERN Document Server

    Jung, S S; Han, S T; Jeon, S; Soukhov, A V; Park, G S

    2001-01-01

    Summary form only given. A 1.5 octave wideband traveling wave tube (TWT) with a helical structure loaded by the thick dielectric support rods has been designed and fabricated for the frequency range of 6-18 GHz. Helical slow-wave structure (SWS) was modeled using three- dimensional HFSS code. The nonresonant perturbation measurement using a thin copper wire with 20 mm diameter was performed to verify the phase velocity and interaction impedance of the helical structure. The performance of TWT was predicted using one-dimensional (1-D) nonlinear theory involving a macro particle beam model. The harmonic effect was considered in this calculation. The measured performance of TWT using a beam voltage 4 kV and a beam current of 120 mA was shown. These results were compared with a 1-D nonlinear theory. The comparison showed that the measured power and gain were less than the predicted one but had a similar trend over the operating frequency range. The 2nd harmonic levels at the low frequency range of 6-8 GHz were ne...

  1. Ring-plane traveling-wave tube slow-wave circuit design simulations at V-Band frequencies

    Science.gov (United States)

    Kory, Carol L.; Wilson, Jeffrey D.

    1995-01-01

    The V-Band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for intersatellite communications. As a first effort to develop a high-efficiency V-band TWT, variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite the high-power capabilities of the ring-plane TWT, disadvantages of low bandwidth and high voltage requirements have until now prevented its acceptance outside the laboratory. In this paper, we use the three-dimensional electromagnetic simulation code MAFIA to investigate methods of increasing the bandwidth and lowering the operating voltage. Dispersion, impedance, and attenuation calculations for various geometric variations and loading distributions were performed. Based on the results of the variations, a circuit termed the finned-ladder TWT slowwave circuit was designed and is compared here to the scaled ring-plane prototype and the conventional ferruled coupled-cavity TWT circuit over the V-band frequency range.

  2. Comparison of slowness profiles of lamb wave with elastic moduli and crystal structure in single crystalline silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Min, Young Jae; Yun, Gyeong Won; Kim, Kyung Min; Roh, Yuji; Kim, Young H. [Applied Acoustics Lab, Korea Science Academy of KAIST, Busan (Korea, Republic of)

    2016-02-15

    Single crystalline silicon wafers having (100), (110), and (111) directions are employed as specimens for obtaining slowness profiles. Leaky Lamb waves (LLW) from immersed wafers were detected by varying the incident angles of the specimens and rotating the specimens. From an analysis of LLW signals for different propagation directions and phase velocities of each specimen, slowness profiles were obtained, which showed a unique symmetry with different symmetric axes. Slowness profiles were compared with elastic moduli of each wafer. They showed the same symmetries as crystal structures. In addition, slowness profiles showed expected patterns and values that can be inferred from elastic moduli. This implies that slowness profiles can be used to examine crystal structures of anisotropic solids.

  3. Design and Experimental Demonstration of Cherenkov Radiation Source Based on Metallic Photonic Crystal Slow Wave Structure

    Science.gov (United States)

    Fu, Tao; Yang, Zi-Qiang; Ouyang, Zheng-Biao

    2016-11-01

    This paper presents a kind of Cherenkov radiation source based on metallic photonic crystal (MPC) slow-wave structure (SWS) cavity. The Cherenkov source designed by linear theory works at 34.7 GHz when the cathode voltage is 550 kV. The three-dimensional particle-in-cell (PIC) simulation of the SWS shows the operating frequency of 35.56 GHz with a single TM01 mode is basically consistent with the theoretically one under the same parameters. An experiment was implemented to testify the results of theory and PIC simulation. The experimental system includes a cathode emitting unit, the SWS, a magnetic system, an output antenna, and detectors. Experimental results show that the operating frequency through detecting the retarded time of wave propagation in waveguides is around 35.5 GHz with a single TM01 mode and an output power reaching 54 MW. It indicates that the MPC structure can reduce mode competition. The purpose of the paper is to show in theory and in preliminary experiment that a SWS with PBG can produce microwaves in TM01 mode. But it still provides a good experimental and theoretical foundation for designing high-power microwave devices.

  4. Radio-frequency sheath voltages and slow wave electric field spatial structure

    Energy Technology Data Exchange (ETDEWEB)

    Colas, Laurent, E-mail: laurent.colas@cea.fr; Lu, Ling-Feng [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Křivská, Alena [LPP-ERM-KMS, TEC partner, Brussels (Belgium); Jacquot, Jonathan [Max-Planck-Institut für Plasmaphysik, Garching (Germany)

    2015-12-10

    We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the RF parallel electric field emitted by Ion Cyclotron (IC) wave launchers, using a simple model of Slow Wave (SW) evanescence coupled with Direct Current (DC) plasma biasing via sheath boundary conditions in a plasma-filled 2-dimensional (parallel, radial) rectangle. Within a “wide sheaths” asymptotic regime, valid for large-amplitude near RF fields, our model becomes partly linear: the sheath oscillating voltage at open field line boundaries is a linear combination of elementary contributions by every source point of the radiated RF field map. These individual contributions are all the more intense as the SW emission point is toroidally nearer to the sheath walls. A limit formula is given for a source infinitely close to the sheaths. The decay of sheath RF voltages with the sheath/source parallel distance is quantified as a function of two characteristic SW evanescence lengths. Decay lengths are smaller than antenna parallel extensions. The sheath RF voltages at an IC antenna side limiter are therefore mainly sensitive to SW emission near this limiter, as recent observations suggest. Toroidal proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel anti-symmetry of the radiated field map. They could also justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

  5. On the Properties of Slow MHD Sausage Waves within Small-scale Photospheric Magnetic Structures

    Science.gov (United States)

    Freij, N.; Dorotovič, I.; Morton, R. J.; Ruderman, M. S.; Karlovský, V.; Erdélyi, R.

    2016-01-01

    The presence of magnetoacoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magnetoacoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope and Rapid Oscillations in the Solar Atmosphere instruments, we captured two series of high-resolution intensity images with short cadences of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to 20 minutes. Combining wavelet analysis and EMD enables us to confidently find the phase difference between the area and intensity oscillations. From these observed features, we concluded that the detected oscillations can be classified as slow sausage MHD waves. Furthermore, we determined several key properties of these oscillations such as the radial velocity perturbation, the magnetic field perturbation, and the vertical wavenumber using SMS. The estimated range of the related wavenumbers reveals that these oscillations are trapped within these magnetic structures. Our results suggest that the detected oscillations are standing harmonics, and this allows us to estimate the expansion factor of the waveguides by employing SMS. The calculated expansion factor ranges from 4 to 12.

  6. ON THE PROPERTIES OF SLOW MHD SAUSAGE WAVES WITHIN SMALL-SCALE PHOTOSPHERIC MAGNETIC STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    Freij, N.; Ruderman, M. S.; Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom); Dorotovič, I. [Slovak Central Observatory, P.O. Box 42, SK-94701 Hurbanovo (Slovakia); Morton, R. J. [Mathematical Modelling Lab, Northumbria University, Pandon Building, Camden Street, Newcastle upon Tyne, NE1 8ST (United Kingdom); Karlovský, V., E-mail: n.freij@sheffield.ac.uk, E-mail: ivan.dorotovic@suh.sk, E-mail: richard.morton@northumbria.ac.uk, E-mail: m.s.ruderman@sheffield.ac.uk, E-mail: astrokar@hl.cora.sk, E-mail: robertus@sheffield.ac.uk [Hlohovec Observatory and Planetarium, Sládkovičova 41, SK-92001 Hlohovec (Slovakia)

    2016-01-20

    The presence of magnetoacoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magnetoacoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope and Rapid Oscillations in the Solar Atmosphere instruments, we captured two series of high-resolution intensity images with short cadences of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to 20 minutes. Combining wavelet analysis and EMD enables us to confidently find the phase difference between the area and intensity oscillations. From these observed features, we concluded that the detected oscillations can be classified as slow sausage MHD waves. Furthermore, we determined several key properties of these oscillations such as the radial velocity perturbation, the magnetic field perturbation, and the vertical wavenumber using SMS. The estimated range of the related wavenumbers reveals that these oscillations are trapped within these magnetic structures. Our results suggest that the detected oscillations are standing harmonics, and this allows us to estimate the expansion factor of the waveguides by employing SMS. The calculated expansion factor ranges from 4 to 12.

  7. Design of a metamaterial slow wave structure for an O-type high power microwave generator

    Science.gov (United States)

    Yurt, Sabahattin C.; Fuks, Mikhail I.; Prasad, Sarita; Schamiloglu, Edl

    2016-12-01

    We describe a new O-type high power microwave oscillator that uses a metamaterial slow wave structure (MSWS) supporting waves with negative dispersion. The MSWS comprises periodically alternating, oppositely oriented split ring resonators (SRRs) connected to a metal tube where the distance between the rings is much less than a wavelength of the radiation generated. The SRRs provide negative permeability μ . The diameter of the metal tube is such that the generated oscillations are below cutoff for a regular waveguide with the same dimension, thus providing negative permittivity ɛ . A tubular electron beam propagates coaxially through this structure. The interaction space is coupled with the outer coaxial channel through gaps between the SRRs. Radiation is extracted in an endfire manner at the end of the outer channel via a conical horn section. Using particle-in-cell (PIC) simulations, it was found that the electron beam in the interaction space forms a sequence of trapped electron bunches by the synchronous operating wave. The output parameters of this oscillator for an applied voltage U = 400 kV, electron beam current I = 4.5 kA, and guide axial magnetic field B = 2 T are radiation power P = 260 MW, radiation frequency f = 1.4 GHz, and electronic efficiency η = 15% when the total SWS length L consisting of 12 split rings is 34.5 cm. The output radiation pattern corresponds to a TE21-like hybrid mode. This article presents details on the simulations of this novel structure and computational and experimental cold tests of a prototype structure in preparation for experimental hot tests.

  8. Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep.

    Science.gov (United States)

    Onisawa, Naomi; Manabe, Hiroyuki; Mori, Kensaku

    2017-01-01

    During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition.

  9. Estimating a continuous p-wave velocity profile with constant squared-slowness gradient models from seismic field data

    NARCIS (Netherlands)

    Ponomarenko, A.V.; Kashtan, B.M.; Troyan, V.N.; Mulder, W.A.

    2015-01-01

    We inverted seismic field data for a continuous, laterally invariant P-wave velocity profile. Instead of the usual approach that involves horizontal layers with piecewise constant densities and velocities, we consider models of one or two layers with a constant gradient of the squared slowness above

  10. Validation of HFCS-I on Calculation of High-Frequency Parameters of Helical Slow-Wave Structures

    Science.gov (United States)

    Zhu, Xiaofang; Yang, Zhonghai; Li, Bin; Li, Jianqing; Xu, Li

    2010-02-01

    To validate HFCS-I, a newly developed design tool for high frequency circuits of microwave tubes, the high-frequency parameters (including dispersion, interaction impedance and attenuation constant) of a typical helical slow-wave structure (SWS) for millimetre wave travelling-wave tube are calculated by HFCS-I and MAFIA. Both the direct calculation method and the Non-Resonant Perturbation (NRP) technique are adopted to get the interaction impedance. The obtained high-frequency parameters from HFCS-I and MAFIA are compared in detail and the consistency has proved the reliability and validity of HFCS-I.

  11. Slow-wave sleep-imposed replay modulates both strength and precision of memory.

    Science.gov (United States)

    Barnes, Dylan C; Wilson, Donald A

    2014-04-09

    Odor perception is hypothesized to be an experience-dependent process involving the encoding of odor objects by distributed olfactory cortical ensembles. Olfactory cortical neurons coactivated by a specific pattern of odorant evoked input become linked through association fiber synaptic plasticity, creating a template of the familiar odor. In this way, experience and memory play an important role in odor perception and discrimination. In other systems, memory consolidation occurs partially via slow-wave sleep (SWS)-dependent replay of activity patterns originally evoked during waking. SWS is ideal for replay given hyporesponsive sensory systems, and thus reduced interference. Here, using artificial patterns of olfactory bulb stimulation in a fear conditioning procedure in the rat, we tested the effects of imposed post-training replay during SWS and waking on strength and precision of pattern memory. The results show that imposed replay during post-training SWS enhanced the subsequent strength of memory, whereas the identical replay during waking induced extinction. The magnitude of this enhancement was dependent on the timing of imposed replay relative to cortical sharp-waves. Imposed SWS replay of stimuli, which differed from the conditioned stimulus, did not affect conditioned stimulus memory strength but induced generalization of the fear memory to novel artificial patterns. Finally, post-training disruption of piriform cortex intracortical association fiber synapses, hypothesized to be critical for experience-dependent odor coding, also impaired subsequent memory precision but not strength. These results suggest that SWS replay in the olfactory cortex enhances memory consolidation, and that memory precision is dependent on the fidelity of that replay.

  12. TMS-induced cortical potentiation during wakefulness locally increases slow wave activity during sleep.

    Directory of Open Access Journals (Sweden)

    Reto Huber

    Full Text Available BACKGROUND: Sleep slow wave activity (SWA is thought to reflect sleep need, increasing in proportion to the length of prior wakefulness and decreasing during sleep. However, the process responsible for SWA regulation is not known. We showed recently that SWA increases locally after a learning task involving a circumscribed brain region, suggesting that SWA may reflect plastic changes triggered by learning. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis directly, we used transcranial magnetic stimulation (TMS in conjunction with high-density EEG in humans. We show that 5-Hz TMS applied to motor cortex induces a localized potentiation of TMS-evoked cortical EEG responses. We then show that, in the sleep episode following 5-Hz TMS, SWA increases markedly (+39.1+/-17.4%, p<0.01, n = 10. Electrode coregistration with magnetic resonance images localized the increase in SWA to the same premotor site as the maximum TMS-induced potentiation during wakefulness. Moreover, the magnitude of potentiation during wakefulness predicts the local increase in SWA during sleep. CONCLUSIONS/SIGNIFICANCE: These results provide direct evidence for a link between plastic changes and the local regulation of sleep need.

  13. Cardiovascular and respiratory changes during slow-wave sleep in rats are associated with electrocorticogram desynchronization

    Directory of Open Access Journals (Sweden)

    J.R. Dias-dos-Santos

    1997-11-01

    Full Text Available In awake rats a single recurrent larger tidal volume (deep breaths occurs at regular intervals, followed by oscillations in arterial pressure and heart rate. In the present study we recorded the changes in blood pressure, heart rate and ventilation during the wakefulness-sleep cycle identified by electrocorticographic records in order to determine whether the deep breaths and cardiovascular oscillations were associated with changes in the electrocorticogram. During several episodes of slow-wave sleep (SWS in 7 rats the deep breaths and oscillations in arterial pressure and heart rate were preceded by SWS desynchronization. The interval between deep breaths during SWS was 71 ± 4 s, the period between initial desynchronization and the generation of deep breaths was 3.98 ± 0.45 s and the duration of SWS desynchronization was 11 ± 0.65 s. Hypotension (-16 ± 1 mmHg and tachycardia (+15 ± 5 bpm were observed during deep breaths in the SWS state. These data indicate that the oscillations in arterial pressure and heart rate during SWS are associated with deep breaths, which in turn are preceded by desynchronization of the electrocorticogram in this state of sleep

  14. Increased frontal sleep slow wave activity in adolescents with major depression

    Directory of Open Access Journals (Sweden)

    Noemi Tesler

    2016-01-01

    Full Text Available Sleep slow wave activity (SWA, the major electrophysiological characteristic of deep sleep, mirrors both cortical restructuring and functioning. The incidence of Major Depressive Disorder (MDD substantially rises during the vulnerable developmental phase of adolescence, where essential cortical restructuring is taking place. The goal of this study was to assess characteristics of SWA topography in adolescents with MDD, in order to assess abnormalities in both cortical restructuring and functioning on a local level. All night high-density EEG was recorded in 15 patients meeting DSM-5 criteria for MDD and 15 sex- and age-matched healthy controls. The actual symptom severity was assessed using the Children's Depression Rating Scale—Revised (CDRS-R. Topographical power maps were calculated based on the average SWA of the first non-rapid eye movement (NREM sleep episode. Depressed adolescents exhibited significantly more SWA in a cluster of frontal electrodes compared to controls. SWA over frontal brain regions correlated positively with the CDRS-R subscore “morbid thoughts”. Self-reported sleep latency was significantly higher in depressed adolescents compared to controls whereas sleep architecture did not differ between the groups. Higher frontal SWA in depressed adolescents may represent a promising biomarker tracing cortical regions of intense use and/or restructuring.

  15. Stability of Brillouin flow in the presence of slow-wave structure

    Science.gov (United States)

    Simon, D. H.; Lau, Y. Y.; Greening, G.; Wong, P.; Hoff, B.; Gilgenbach, R. M.

    2016-09-01

    Including a slow-wave structure (SWS) on the anode in the conventional, planar, and inverted magnetron, we systematically study the linear stability of Brillouin flow, which is the prevalent flow in crossed-field devices. The analytic treatment is fully relativistic and fully electromagnetic, and it incorporates the equilibrium density profile, flow profile, and electric field and magnetic field profiles in the linear stability analysis. Using parameters similar to the University of Michigan's recirculating planar magnetron, the numerical data show that the resonant interaction of the vacuum circuit mode and the corresponding smooth-bore diocotron-like mode is the dominant cause for instability. This resonant interaction is far more important than the intrinsic negative (positive) mass property of electrons in the inverted (conventional) magnetron geometry. It is absent in either the smooth-bore magnetron or under the electrostatic assumption, one or both of which was almost always adopted in prior analytical formulation. This resonant interaction severely restricts the wavenumber for instability to the narrow range in which the cold tube frequency of the SWS is within a few percent of the corresponding smooth bore diocotron-like mode in the Brillouin flow.

  16. Thermoregulatory adjustments to thermal transients during slow wave sleep and REM sleep in man.

    Science.gov (United States)

    Libert, J P; Candas, V; Muzet, A; Ehrhart, J

    1982-01-01

    The present study was performed on five nude male subjects by increasing the ambient temperature during well-established slow wave sleep (SWS) and rapid eye movement (REM) sleep episodes. 1. Air temperature was raised from 25 to 41 degrees C at rates of + 0.8 degrees C.min-1 or + 1.6 degrees C min-1 and, afterwards, was maintained at 41 degrees C during 10 min before returning to the initial pre-heating condition. During these thermal transients, wall temperatures (Tw), dew-point temperature (Tdp) and air velocity (Va) were kept constant (Tw = 37.5 degrees C; Tdp = 10 degrees C; Va = 0.3 m.s.-1). Physiological data included 3 EEGs, 2 EOGs, 4 EMGs, heart rate, finger pulse amplitude, esophageal temperature and 10 local skin temperatures. Upper chest sweating rate was recorded by a 12 cm2-capsule using a dew-point hygrometer technique. 2. The results showed that during REM sleep sweat gland activity persists at a lower level than during SWS. The lower sensitivity of the thermoregulatory system described during the REM sleep episodes could be interpreted by an increase of the hypothalamic set-point temperature, or by an action of extra-hypothalamic thermosensitive neurons. However, a change at the sweat gland level cannot be ruled out.

  17. Low acetylcholine during slow-wave sleep is critical for declarative memory consolidation.

    Science.gov (United States)

    Gais, Steffen; Born, Jan

    2004-02-17

    The neurotransmitter acetylcholine is considered essential for proper functioning of the hippocampus-dependent declarative memory system, and it represents a major neuropharmacological target for the treatment of memory deficits, such as those in Alzheimer's disease. During slow-wave sleep (SWS), however, declarative memory consolidation is particularly strong, while acetylcholine levels in the hippocampus drop to a minimum. Observations in rats led to the hypothesis that the low cholinergic tone during SWS is necessary for the replay of new memories in the hippocampus and their long-term storage in neocortical networks. However, this low tone should not affect nondeclarative memory systems. In this study, increasing central nervous cholinergic activation during SWS-rich sleep by posttrial infusion of 0.75 mg of the cholinesterase inhibitor physostigmine completely blocked SWS-related consolidation of declarative memories for word pairs in human subjects. The treatment did not interfere with consolidation of a nondeclarative mirror tracing task. Also, physostigmine did not alter memory consolidation during waking, when the endogenous central nervous cholinergic tone is maximal. These findings are in line with predictions that a low cholinergic tone during SWS is essential for declarative memory consolidation.

  18. A Ku-band magnetically insulated transmission line oscillator with overmoded slow-wave-structure

    Science.gov (United States)

    Jiang, Tao; He, Jun-Tao; Zhang, Jian-De; Li, Zhi-Qiang; Ling, Jun-Pu

    2016-12-01

    In order to enhance the power capacity, an improved Ku-band magnetically insulated transmission line oscillator (MILO) with overmoded slow-wave-structure (SWS) is proposed and investigated numerically and experimentally. The analysis of the dispersion relationship and the resonant curve of the cold test indicate that the device can operate at the near π mode of the TM01 mode, which is useful for mode selection and control. In the particle simulation, the improved Ku-band MILO generates a microwave with a power of 1.5 GW and a frequency of 12.3 GHz under an input voltage of 480 kV and input current of 42 kA. Finally, experimental investigation of the improved Ku-band MILO is carried out. A high-power microwave (HPM) with an average power of 800 MW, a frequency of 12.35 GHz, and pulse width of 35 ns is generated under a diode voltage of 500 kV and beam current of 43 kA. The consistency between the experimental and simulated far-field radiation pattern confirms that the operating mode of the improved Ku-band MILO is well controlled in π mode of the TM01 mode. Project supported partly by the National Natural Science Foundation of China (Grant No. 61171021).

  19. The role of non-rapid eye movement slow-wave activity in prefrontal metabolism across young and middle-aged adults.

    Science.gov (United States)

    Wilckens, Kristine A; Aizenstein, Howard J; Nofzinger, Eric A; James, Jeffrey A; Hasler, Brant P; Rosario-Rivera, Bedda L; Franzen, Peter L; Germain, Anne; Hall, Martica H; Kupfer, David J; Price, Julie C; Siegle, Greg J; Buysse, Daniel J

    2016-06-01

    Electroencephalographic slow-wave activity (0.5-4 Hz) during non-rapid eye movement (NREM) sleep is a marker for cortical reorganization, particularly within the prefrontal cortex. Greater slow wave activity during sleep may promote greater waking prefrontal metabolic rate and, in turn, executive function. However, this process may be affected by age. Here we examined whether greater NREM slow wave activity was associated with higher prefrontal metabolism during wakefulness and whether this relationship interacted with age. Fifty-two participants aged 25-61 years were enrolled into studies that included polysomnography and a (18) [F]-fluoro-deoxy-glucose positron emission tomography scan during wakefulness. Absolute and relative measures of NREM slow wave activity were assessed. Semiquantitative and relative measures of cerebral metabolism were collected to assess whole brain and regional metabolism, focusing on two regions of interest: the dorsolateral prefrontal cortex and the orbitofrontal cortex. Greater relative slow wave activity was associated with greater dorsolateral prefrontal metabolism. Age and slow wave activity interacted significantly in predicting semiquantitative whole brain metabolism and outside regions of interest in the posterior cingulate, middle temporal gyrus and the medial frontal gyrus, such that greater slow-wave activity was associated with lower metabolism in the younger participants and greater metabolism in the older participants. These results suggest that slow-wave activity is associated with cerebral metabolism during wakefulness across the adult lifespan within regions important for executive function.

  20. "Slowing" Mechanical Waves with a Consumer-Type High-Speed Digital Camera

    Science.gov (United States)

    Ng, Pun-hon; Chan, Kin-lok

    2015-01-01

    In most secondary physics textbooks, waves are first introduced with examples of mechanical waves because they can be illustrated by drawings and photographs. However, these illustrations are static and cannot reflect the dynamic nature of waves. Although many mechanical waves (e.g. water waves and vibrating strings) can be easily shown using…

  1. Consciousness Can Change the Output Signals of a Solar Cell and the Photoelectric Conversion Equation of Slow Mass Wave

    Science.gov (United States)

    Cao, Dayong

    2009-03-01

    The experiment's results show that human consciousness can change output signals such as Voc (open-circuit voltage) and Isc (short circuit current) of a solar cell placed some distance from a participant. For the first time, a consciousness signal is able to be recorded through the experiment conducted in Oct 2002. The order and rhythm of the changing wave pattern of Voc is related to the action of consciousness. The order and rhythm of slow brain signal of ERP and EEG are related to the cognized objects. Consciousness is independent and self-determined while brain signal is passive and driven. Consciousness is spiritual and Intelligence while brain signal is physical, corporality and mechanic. So consciousness is different from the brain signal. And consciousness effection is different from physical effection of light. Because consciousness can choose the object which it acts on. The light have a pairt of mass wave of low frequency and energy wave of high frequency. In photoelectric conversion process, We only use the energy wave to get the η (photoelectric transformation efficiency) which is little. If being used a pairt of wave, we will get a larger η. The photoelectric conversion equation of slow mass wave are being put forward.

  2. Pearson相关系数法快慢横波波场分离%Wave filed separation of fast-slow shear waves by Pearson correlation coefficient method

    Institute of Scientific and Technical Information of China (English)

    王凯; 冯晅; 刘财

    2012-01-01

    横波分裂是各向异性介质的重要特征,当横波或转换波穿过各向异性介质到达地面时,地面三分量检波器的x分量和y分量接收到的地震记录中都会同时存在快横波和慢横波.将快横波和慢横波进行分离,进而计算介质的各向异性参数是多分量数据处理中重要的一步.将数学中的Pearson相关系数引入到多分量地震勘探中,提出了Pearson相关系数法进行旋转角度识别,进而分离快、慢横波波场.相比于传统的互相关法,Pearson相关系数法从精度、抗噪性能和计算效率上都有提高.%Shear-wave splitting is an important characteristic of anisotropic media. Generally, when S or P-SV waves reach to the ground through anisotropic media, the seismic record received by x component and y component of three-component detector contains fast wave and slow wave simultaneously- Separating fast wave and slow wave and then calculating the anisotropic parameters of media are an important step in multi-component data processing. The authors introduce the Pearson correlation coefficients into multi-component seismic exploration and propose the Pearson correlation coefficients to detect the rotation angle and then separate the fast wave and slow wave. Compared with the traditional cross-correlation method, the Pearson correlation coefficient method is better in accuracy, noise immunity and computational efficiency.

  3. Spatial organization and coordination of slow waves in the mouse anorectum.

    Science.gov (United States)

    Hall, K A; Ward, S M; Cobine, C A; Keef, K D

    2014-09-01

    The internal anal sphincter (IAS) develops tone and is important for maintaining a high anal pressure while tone in the rectum is less. The mechanisms responsible for tone generation in the IAS are still uncertain. The present study addressed this question by comparing the electrical properties and morphology of the mouse IAS and distal rectum. The amplitude of tone and the frequency of phasic contractions was greater in the IAS than in rectum while membrane potential (Em) was less negative in the IAS than in rectum. Slow waves (SWs) were of greatest amplitude and frequency at the distal end of the IAS, declining in the oral direction. Dual microelectrode recordings revealed that SWs were coordinated over a much greater distance in the circumferential direction than in the oral direction. The circular muscle layer of the IAS was divided into five to eight 'minibundles' separated by connective tissue septa whereas few septa were present in the rectum. The limited coordination of SWs in the oral direction suggests that the activity in adjacent minibundles is not coordinated. Intramuscular interstitial cells of Cajal and platelet-derived growth factor receptor alpha-positive cells were present in each minibundle suggesting a role for one or both of these cells in SW generation. In summary, three important properties distinguish the IAS from the distal rectum: (1) a more depolarized Em; (2) larger and higher frequency SWs; and (3) the multiunit configuration of the muscle. All of these characteristics may contribute to greater tone generation in the IAS than in the distal rectum.

  4. Reduction in Cortical Gamma Synchrony during Depolarized State of Slow Wave Activity in Mice

    Directory of Open Access Journals (Sweden)

    EUNJIN eHWANG

    2013-12-01

    Full Text Available EEG gamma band oscillations have been proposed to account for the neural synchronization crucial for perceptual integration. While increased gamma power and synchronization is generally observed during cognitive tasks performed during wake, several studies have additionally reported increased gamma power during sleep or anesthesia, raising questions about the characteristics of gamma oscillation during impaired consciousness and its role in conscious processing. Phase-amplitude modulation has been observed between slow wave activity (SWA, 0.5–4 Hz and gamma oscillations during ketamine/xylazine anesthesia or sleep, showing increased gamma activity corresponding to the depolarized (ON state of SWA. Here we divided gamma activity into its ON and OFF (hyperpolarized state components based on the phase of SWA induced by ketamine/xylazine anesthesia and compared their power and synchrony with wake state levels in mice. We further investigated the state-dependent changes in both gamma power and synchrony across primary motor and primary somatosensory cortical regions and their interconnected thalamic regions throughout anesthesia and recovery. As observed previously, gamma power was as high as during wake specifically during the ON state of SWA. However, the synchrony of this gamma activity between somatosensory-motor cortical regions was significantly reduced compared to the baseline wake state. In addition, the somatosensory-motor cortical synchrony of gamma oscillations was reduced and restored in an anesthetic state-dependent manner, reflecting the changing depth of anesthesia. Our results provide evidence that during anesthesia changes in long-range information integration between cortical regions might be more critical for changes in consciousness than changes in local gamma oscillatory power.

  5. Characterization of scale-free properties of human electrocorticography in awake and slow wave sleep states

    Directory of Open Access Journals (Sweden)

    John M Zempel

    2012-06-01

    Full Text Available Like many complex dynamic systems, the brain exhibits scale-free dynamics that follow power law scaling. Broadband power spectral density (PSD of brain electrical activity exhibits state-dependent power law scaling with a log frequency exponent that varies across frequency ranges. Widely divergent naturally occurring neural states, awake and slow wave sleep (SWS periods, were used evaluate the nature of changes in scale-free indices. We demonstrate two analytic approaches to characterizing electrocorticographic (ECoG data obtained during Awake and SWS states. A data driven approach was used, characterizing all available frequency ranges. Using an Equal Error State Discriminator (EESD, a single frequency range did not best characterize state across data from all six subjects, though the ability to distinguish awake and SWS states in individual subjects was excellent. Multisegment piecewise linear fits were used to characterize scale-free slopes across the entire frequency range (0.2-200 Hz. These scale-free slopes differed between Awake and SWS states across subjects, particularly at frequencies below 10 Hz and showed little difference at frequencies above 70 Hz. A Multivariate Maximum Likelihood Analysis (MMLA method using the multisegment slope indices successfully categorized ECoG data in most subjects, though individual variation was seen. The ECoG spectrum is not well characterized by a single linear fit across a defined set of frequencies, but is best described by a set of discrete linear fits across the full range of available frequencies. With increasing computational tractability, the use of scale-free slope values to characterize EEG data will have practical value in clinical and research EEG studies.

  6. High quality broadband spatial reflections of slow Rayleigh surface acoustic waves modulated by a graded grooved surface

    KAUST Repository

    Xu, Yanlong

    2015-01-21

    We report high quality broadband spatial reflections of Rayleigh surface acoustic waves (SAWs) through a graded grooved surface. High quality means that no wave is allowed to transmit and the incident wave is nearly all reflected to the input side. The graded grooved surface is structured by drilling one dimensional array of graded grooves with increased depths on a flat surface. We investigate SAW dispersion relations, wave field distribution at several typical SAW wavelengths, and time evolution of a Gaussian pulse through the graded grooved surface. Results show that the input broadband Rayleigh SAWs can be slowed, spatially enhanced and stopped, and finally reflected to the input side. The study suggests that engraving the flat surface can be used as an efficient and economical way to manipulate Rayleigh SAWs, which has potential application in novel SAW devices such as filters, reflectors, sensors, energy harvesters, and diodes.

  7. Migraine aura lasting 1-24 h in children: a sequence of EEG slow-wave abnormalities vs. vascular events.

    Science.gov (United States)

    Parain, D; Hitzel, A; Guegan-Massardier, E; Lebas, A; Blondeau, C; Fédina, I; Feray, D; Véra, P; Mihout, B

    2007-09-01

    The aim of this study was to describe the abnormalities associated with migraine aura lasting 1-24 h in children as shown by EEG, trancranial Doppler (TCD) and single photon emission computed tomography (SPECT). In this retrospective study, 11 patients each underwent EEG, TCD and brain SPECT on the day of admission and the day thereafter. On the day of admission, the migrainous hemisphere of all patients showed that the mean velocities were decreased in the middle cerebral artery by TCD, slow-wave abnormalities were recorded after several hours of aura by EEG and the SPECT showed hypoperfusion. On the day after, in the same hemisphere, slow waves were recorded only in the occipital area by EEG, and SPECT showed slight hyperperfusion. In these patients, there was a clear sequence of EEG, TCD and SPECT abnormalities.

  8. Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves

    Science.gov (United States)

    Restrepo, Simon; Basler, Konrad

    2016-08-01

    Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies.

  9. Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves.

    Science.gov (United States)

    Restrepo, Simon; Basler, Konrad

    2016-08-09

    Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies.

  10. Experimental study on slow flexural waves around the defect modes in a phononic crystal beam using fiber Bragg gratings

    Science.gov (United States)

    Chuang, Kuo-Chih; Zhang, Zhi-Qiang; Wang, Hua-Xin

    2016-12-01

    This work experimentally studies influences of the point defect modes on the group velocity of flexural waves in a phononic crystal Timoshenko beam. Using the transfer matrix method with a supercell technique, the band structures and the group velocities around the defect modes are theoretically obtained. Particularly, to demonstrate the existence of the localized defect modes inside the band gaps, a high-sensitivity fiber Bragg grating sensing system is set up and the displacement transmittance is measured. Slow propagation of flexural waves via defect coupling in the phononic crystal beam is then experimentally demonstrated with Hanning windowed tone burst excitations.

  11. Implementation of dispersion-free slow acoustic wave propagation and phase engineering with helical-structured metamaterials

    Science.gov (United States)

    Zhu, Xuefeng; Li, Kun; Zhang, Peng; Zhu, Jie; Zhang, Jintao; Tian, Chao; Liu, Shengchun

    2016-05-01

    The ability to slow down wave propagation in materials has attracted significant research interest. A successful solution will give rise to manageable enhanced wave-matter interaction, freewheeling phase engineering and spatial compression of wave signals. The existing methods are typically associated with constructing dispersive materials or structures with local resonators, thus resulting in unavoidable distortion of waveforms. Here we show that, with helical-structured acoustic metamaterials, it is now possible to implement dispersion-free sound deceleration. The helical-structured metamaterials present a non-dispersive high effective refractive index that is tunable through adjusting the helicity of structures, while the wavefront revolution plays a dominant role in reducing the group velocity. Finally, we numerically and experimentally demonstrate that the helical-structured metamaterials with designed inhomogeneous unit cells can turn a normally incident plane wave into a self-accelerating beam on the prescribed parabolic trajectory. The helical-structured metamaterials will have profound impact to applications in explorations of slow wave physics.

  12. Implementation of dispersion-free slow acoustic wave propagation and phase engineering with helical-structured metamaterials.

    Science.gov (United States)

    Zhu, Xuefeng; Li, Kun; Zhang, Peng; Zhu, Jie; Zhang, Jintao; Tian, Chao; Liu, Shengchun

    2016-05-20

    The ability to slow down wave propagation in materials has attracted significant research interest. A successful solution will give rise to manageable enhanced wave-matter interaction, freewheeling phase engineering and spatial compression of wave signals. The existing methods are typically associated with constructing dispersive materials or structures with local resonators, thus resulting in unavoidable distortion of waveforms. Here we show that, with helical-structured acoustic metamaterials, it is now possible to implement dispersion-free sound deceleration. The helical-structured metamaterials present a non-dispersive high effective refractive index that is tunable through adjusting the helicity of structures, while the wavefront revolution plays a dominant role in reducing the group velocity. Finally, we numerically and experimentally demonstrate that the helical-structured metamaterials with designed inhomogeneous unit cells can turn a normally incident plane wave into a self-accelerating beam on the prescribed parabolic trajectory. The helical-structured metamaterials will have profound impact to applications in explorations of slow wave physics.

  13. Involvement of Spindles in Memory Consolidation Is Slow Wave Sleep-Specific

    Science.gov (United States)

    Cox, Roy; Hofman, Winni F.; Talamini, Lucia M.

    2012-01-01

    Both sleep spindles and slow oscillations have been implicated in sleep-dependent memory consolidation. Whereas spindles occur during both light and deep sleep, slow oscillations are restricted to deep sleep, raising the possibility of greater consolidation-related spindle involvement during deep sleep. We assessed declarative memory retention…

  14. Reflection Of Propagating Slow Magneto-acoustic Waves In Hot Coronal Loops : Multi-instrument Observations and Numerical Modelling

    CERN Document Server

    Mandal, Sudip; Fang, Xia; Banerjee, Dipankar; Pant, Vaibhav; Van Doorsselaere, Tom

    2016-01-01

    Slow MHD waves are important tools for understanding the coronal structures and dynamics. In this paper, we report a number of observations, from X-Ray Telescope (XRT) on board HINODE and SDO/AIA of reflecting longitudinal waves in hot coronal loops. To our knowledge, this is the first report of this kind as seen from the XRT and simultaneously with the AIA. The wave appears after a micro-flare occurs at one of the footpoints. We estimate the density and the temperature of the loop plasma by performing DEM analysis on the AIA image sequence. The estimated speed of propagation is comparable or lower than the local sound speed suggesting it to be a propagating slow wave. The intensity perturbation amplitudes, in every case, falls very rapidly as the perturbation moves along the loop and eventually vanishes after one or more reflections. To check the consistency of such reflection signatures with the obtained loop parameters, we perform a 2.5D MHD simulation, which uses the parameters obtained from our observati...

  15. Evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow-mode waves

    CERN Document Server

    Wang, Tongjiang; Sun, Xudong; Provornikova, Elena; Davila, Joseph M

    2015-01-01

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ~12 min and a decay time of ~9 min. The measured phase speed of 500$\\pm$50 km/s matches the sound speed in the heated loop of ~10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet (EUV) channels, and find that they are nearly in phase.The measured polytropic index from the temperature and density perturbations is 1.64$\\pm$0.08 close to the adiabatic index ...

  16. Slow light in the GaAs-rod-loaded metallic waveguide for terahertz wave.

    Science.gov (United States)

    Wang, Wei; He, Jinlong; Li, Xiangjun; Hong, Zhi

    2010-05-24

    The modes in a circular metallic waveguide loaded with a high permittivity dielectric rod may possess similar dispersion relations to the modes in the left-handed metamaterial (LHM) waveguide. Therefore such dielectric-loaded metallic waveguide may also support slow light with parameters properly selected. The slow light in the GaAs-rod-loaded metallic waveguide is numerically studied. The results show that the wavelength of slow light varies with the parameters of the waveguide. A linearly tapered waveguide and other realizable simple structures are proposed accordingly to realize the "trapped rainbow" phenomena. Moreover, the practical lossy tapered waveguide is also investigated in the terahertz region. It is shown that the slow light with low loss can be achieved in a realistic GaAs-loaded metallic waveguide.

  17. EVIDENCE OF THERMAL CONDUCTION SUPPRESSION IN A SOLAR FLARING LOOP BY CORONAL SEISMOLOGY OF SLOW-MODE WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tongjiang; Ofman, Leon; Provornikova, Elena [Department of Physics, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Sun, Xudong [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Davila, Joseph M., E-mail: tongjiang.wang@nasa.gov [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20770 (United States)

    2015-09-20

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 Å images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ∼12 minutes and a decay time of ∼9 minutes. The measured phase speed of 500 ± 50 km s{sup −1} matches the sound speed in the heated loop of ∼10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an ideal monatomic gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit.

  18. Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design

    Science.gov (United States)

    Kory, Carol L.; Wilson, Jeffrey D.

    1994-01-01

    The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

  19. Apolipoprotein E4 Causes Age-Dependent Disruption of Slow Gamma Oscillations during Hippocampal Sharp-Wave Ripples.

    Science.gov (United States)

    Gillespie, Anna K; Jones, Emily A; Lin, Yuan-Hung; Karlsson, Mattias P; Kay, Kenneth; Yoon, Seo Yeon; Tong, Leslie M; Nova, Philip; Carr, Jessie S; Frank, Loren M; Huang, Yadong

    2016-05-18

    Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD), but the mechanism by which it causes cognitive decline is unclear. In knockin (KI) mice, human apoE4 causes age-dependent learning and memory impairments and degeneration of GABAergic interneurons in the hippocampal dentate gyrus. Here we report two functional apoE4-KI phenotypes involving sharp-wave ripples (SWRs), hippocampal network events critical for memory processes. Aged apoE4-KI mice had fewer SWRs than apoE3-KI mice and significantly reduced slow gamma activity during SWRs. Elimination of apoE4 in GABAergic interneurons, which prevents learning and memory impairments, rescued SWR-associated slow gamma activity but not SWR abundance in aged mice. SWR abundance was reduced similarly in young and aged apoE4-KI mice; however, the full SWR-associated slow gamma deficit emerged only in aged apoE4-KI mice. These results suggest that progressive decline of interneuron-enabled slow gamma activity during SWRs critically contributes to apoE4-mediated learning and memory impairments. VIDEO ABSTRACT.

  20. Simultaneous stimulation of slow-wave sleep and growth hormone secretion by gamma-hydroxybutyrate in normal young Men.

    OpenAIRE

    Van Cauter, E; Plat, L; Scharf, M B; R Leproult; Cespedes, S; L'Hermite-Balériaux, M; Copinschi, G..

    1997-01-01

    The aim of this study was to investigate, in normal young men, whether gamma-hydroxybutyrate (GHB), a reliable stimulant of slow-wave (SW) sleep in normal subjects, would simultaneously enhance sleep related growth hormone (GH) secretion. Eight healthy young men participated each in four experiments involving bedtime oral administration of placebo, 2.5, 3.0, and 3.5 g of GHB. Polygraphic sleep recordings were performed every night, and blood samples were obtained at 15-min intervals from 2000...

  1. Characteristics of Arbitrarily-Shaped Helical Groove Slow-Wave Structure Loaded with a Concentric Dielectric-Rod

    Science.gov (United States)

    Gong, Yu-Bin; Wei, Yan-Yu; Liu, Hong-Tao

    2010-12-01

    The dielectric-rod is loaded on the central axis of the arbitrarily-shaped helical groove slow-wave structure. Meanwhile, the profile of the groove is replaced by a series of continuous rectangular steps. The unified dispersion equation of the arbitrarily-shaped helical groove waveguide loaded with a concentric dielectric-rod is obtained by means of a combination of filed-matching method and admittance-matching technique. Then, the effect of the change of groove shape and the dielectric-rod parameters on the dispersion and coupling impedance is approached by theory calculation. The results show that: loaded with dielectric-rod, the bandwidth of the helical groove traveling wave tube (TWT) is effectively broadened, but the coupling impedance is reduced. Among the five different groove shapes, the triangle-type groove has the widest bandwidth but the smallest coupling impedance, and the swallow-tailed-type groove has the narrowest bandwidth but the largest coupling impedance.

  2. 'Catching the waves' - slow cortical potentials as moderator of voluntary action.

    Science.gov (United States)

    Schmidt, Stefan; Jo, Han-Gue; Wittmann, Marc; Hinterberger, Thilo

    2016-09-01

    The readiness potential is an ongoing negativity in the EEG preceding a self-initiated movement by approximately 1.5s. So far it has predominantly been interpreted as a preparatory signal with a causal link to the upcoming movement. Here a different hypothesis is suggested which we call the selective slow cortical potential sampling hypothesis. In this review of recent research results we argue that the initiation of a voluntary action is more likely during negative fluctuations of the slow cortical potential and that the sampling and averaging of many trials leads to the observed negativity. That is, empirical evidence indicates that the early readiness potential is not a neural correlate of preconscious motor preparation and thus a determinant of action. Our hypothesis thereafter challenges the classic interpretation of the Libet experiment which is often taken as proof that there is no free will. We furthermore suggest that slow cortical potentials are related to an urge to act but are not a neural indicator of the decision process of action initiation.

  3. Long-term history and immediate preceding state affect EEG slow wave characteristics at NREM sleep onset in C57BL/6 mice.

    Science.gov (United States)

    Cui, N; Mckillop, L E; Fisher, S P; Oliver, P L; Vyazovskiy, V V

    2014-01-01

    The dynamics of cortical activity across the 24-h day and at vigilance state transitions is regulated by an interaction between global subcortical neuromodulatory influences and local shifts in network synchrony and excitability. To address the role of long-term and immediate preceding history in local and global cortical dynamics, we investigated cortical EEG recorded from both frontal and occipital regions during an undisturbed 24-h recording in mice. As expected, at the beginning of the light period, under physiologically increased sleep pressure, EEG slow waves were more frequent and had higher amplitude and slopes, compared to the rest of the light period. Within discrete NREM sleep episodes, the incidence, amplitude and slopes of individual slow waves increased progressively after episode onset in both derivations by approximately 10-30%. Interestingly, at the beginning of NREM sleep episodes slow waves in the frontal and occipital derivations frequently occurred in isolation, as quantified by longer latencies between consecutive slow waves in the two regions. Notably, slow waves during the initial period of NREM sleep following REM sleep episodes were significantly less frequent, lower in amplitude and exhibited shallower slopes, compared to those that occurred in NREM episodes after prolonged waking. Moreover, the latencies between consecutive frontal and occipital NREM slow waves were substantially longer when they occurred directly after REM sleep compared to following consolidated wakefulness. Overall these data reveal a complex picture, where both time of day and preceding state contribute to the characteristics and dynamics of slow waves within NREM sleep. These findings suggest that NREM sleep initiates in a more "local" fashion when it occurs following REM sleep episodes as opposed to sustained waking bouts. While the mechanisms and functional significance of such a re-setting of brain state after individual REM sleep episodes remains to be

  4. Research on the Characteristic of the Disk-Loaded Waveguide, Rib-Loaded Disk-Loaded Waveguide and Helix Slow-Wave Structures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong

    2005-01-01

    @@ The fast development of modern electronic warfare, broadband high power array radar system, high power jammer and microwave directional power weapon imposes high demand on high power microwave resource. With such features as high power, broadband, multi-mode, etc., traveling wave tubes (TWTs) play an important role in the high power microwave amplifiers. Since the slow-wave system is the core of beam-wave interaction in TWTs, the function and performance of it directly determine the capability of the TWTs.

  5. Slow to superluminal light waves in thin 3D photonic crystals.

    Science.gov (United States)

    Galisteo-López, J F; Galli, M; Balestreri, A; Patrini, M; Andreani, L C; López, C

    2007-11-12

    Phase measurements on self-assembled three-dimensional photonic crystals show that the group velocity of light can flip from small positive (slow) to negative (superluminal) values in samples of a few mum size. This phenomenon takes place in a narrow spectral range around the second-order stop band and follows from coupling to weakly dispersive photonic bands associated with multiple Bragg diffraction. The observations are well accounted for by theoretical calculations of the phase delay and of photonic states in the finite-sized systems.

  6. Analysis and design of the taper in metal-grating periodic slow-wave structures for rectangular Cerenkov masers

    Institute of Scientific and Technical Information of China (English)

    Chen Ye; Zhao Ding; Wang Yong; Shu Wen

    2012-01-01

    The hybrid-mode dispersion equation of the metal-grating periodic slow-wave structure for a rectangular Cerenkov maser is derived by using the Borgnis function and field-matching methods.An equivalent-circuit model for the taper of the groove depth that matches the smooth waveguide to the metal-grating structure is proposed.By using the equivalentcircuit method,as well as the Ansoft high frequency structure simulator(HFSS)code,an appropriate electromagnetic mode for beam-wave interaction is selected and the equivalent-circuit analysis on the taper is given.The calculated results show that a cumulative reflection coefficient of 0.025 for the beam-wave interaction structure at a working frequency of 78.1 GHz can be reached by designing the exponential taper with a TEz10 rectangular waveguide mode as the input and the desired TEχ10 mode as the output.It is worth pointing out that by using the equivalent-circuit method,the complex field-matching problems from the traditional field-theory method for taper design can be avoided,so the taper analysis process is markedly simplified.

  7. Regional variation in contribution of myenteric and intramuscular interstitial cells of Cajal to generation of slow waves in mouse gastric antrum.

    Science.gov (United States)

    Hirst, G D S; Beckett, E A H; Sanders, K M; Ward, S M

    2002-05-01

    When intracellular recordings were made from the antral region of murine stomach, cells with three different patterns of electrical activity were detected. One group of cells generated follower potentials, the second group generated pacemaker potentials and the third group generated slow waves that consisted of primary and secondary components. Slow waves recorded in different regions of the gastric antrum had similar amplitudes but different characteristic shapes. At the greater curvature, slow waves had large initial components. Midway between the greater and lesser curvature, the amplitude of the initial component was reduced and at the lesser curvature an initial component was difficult to detect. When the distributions of myenteric (ICC-MY) and intramuscular interstitial cells of Cajal (ICC-IM) were determined, using an antibody to Kit, ICC-MY were found to be present at the greater curvature but were greatly reduced in density at the lesser curvature. In contrast, ICC-IM were found in the circular layer of each region. When recordings were made from the antrum of W/W(V) mice, which lack ICC-IM, incomplete slow waves were detected and their amplitudes fell from the greater to the lesser curvature. Again, a corresponding fall in the density of ICC-MY was detected. The observations indicate that the contribution of ICC-MY and ICC-IM to the generation of slow waves varies in different regions of the mouse gastric antrum.

  8. On the properties of slow mhd sausage waves within small-scale photospheric magnetic structures

    CERN Document Server

    Freij, N; Morton, R J; Ruderman, M S; Karlovsky, V; Erdekyi, R

    2015-01-01

    The presence of magneto-acoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magneto-acoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope (DOT) and Rapid Oscillations in the Solar Atmosphere (ROSA) instruments, we captured two series of high-resolution intensity images with short cadence of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to ...

  9. Four-wave mixing in photonic crystal waveguides: slow light enhancement and limitations.

    Science.gov (United States)

    Li, Juntao; O'Faolain, Liam; Rey, Isabella H; Krauss, Thomas F

    2011-02-28

    We demonstrate continuous wave four-wave mixing in silicon photonic crystal waveguides of 396 μm length with a group index of ng=30. The highest observed conversion efficiency is -24 dB for 90 mW coupled input pump power. The key question we address is whether the predicted fourth power dependence of the conversion efficiency on the slowdown factor (η≈S4) can indeed be observed in this system, and how the conversion efficiency depends on device length in the presence of propagation losses. We find that the expected dependencies hold as long as both realistic losses and the variation of mode shape with slowdown factor are taken into account. Having achieved a good agreement between a simple analytical model and the experiment, we also predict structures that can achieve the same conversion efficiency as already observed in nanowires for the same input power, yet for a device length that is 50 times shorter.

  10. Ion thermal effects on slow mode solitary waves in plasmas with two adiabatic ion species

    Energy Technology Data Exchange (ETDEWEB)

    Nsengiyumva, F., E-mail: franco.nseng@gmail.com; Hellberg, M. A., E-mail: hellberg@ukzn.ac.za; Mace, R. L., E-mail: macer@ukzn.ac.za [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

    2015-09-15

    Using both the Sagdeev and Korteweg-de Vries (KdV) methods, ion thermal effects on slow mode ion acoustic solitons and double layers are investigated in a plasma with two adiabatic positive ion species. It is found that reducing the gap between the two ion thermal speeds by increasing the relative temperature of the cool ions increases the typical soliton/double layer speeds for all values of the ion-ion density ratio and reduces the range in the density ratio that supports double layers. The effect of increasing the relative cool ion temperature on the soliton/double layer amplitudes depends on the relative densities. For lower values of the ion density ratio, an increase in cool ion temperature leads to a significant decrease in soliton/double layer amplitude, so one may find that solitons of all permissible speeds lie within the range of KdV theory.

  11. A highly efficient CMOS nanoplasmonic crystal enhanced slow-wave thermal emitter improves infrared gas-sensing devices

    Science.gov (United States)

    Pusch, Andreas; de Luca, Andrea; Oh, Sang S.; Wuestner, Sebastian; Roschuk, Tyler; Chen, Yiguo; Boual, Sophie; Ali, Zeeshan; Phillips, Chris C.; Hong, Minghui; Maier, Stefan A.; Udrea, Florin; Hopper, Richard H.; Hess, Ortwin

    2015-12-01

    The application of plasmonics to thermal emitters is generally assisted by absorptive losses in the metal because Kirchhoff’s law prescribes that only good absorbers make good thermal emitters. Based on a designed plasmonic crystal and exploiting a slow-wave lattice resonance and spontaneous thermal plasmon emission, we engineer a tungsten-based thermal emitter, fabricated in an industrial CMOS process, and demonstrate its markedly improved practical use in a prototype non-dispersive infrared (NDIR) gas-sensing device. We show that the emission intensity of the thermal emitter at the CO2 absorption wavelength is enhanced almost 4-fold compared to a standard non-plasmonic emitter, which enables a proportionate increase in the signal-to-noise ratio of the CO2 gas sensor.

  12. Designing slow-light photonic crystal waveguides for four-wave mixing applications.

    Science.gov (United States)

    Kanakis, Panagiotis; Kamalakis, Thomas; Sphicopoulos, Thomas

    2014-02-15

    We discuss the optimization of photonic crystal waveguides for four-wave mixing (FWM) applications, taking into account linear loss and free-carrier effects. Suitable figures of merit are introduced in order to guide us through the choice of practical, high-efficiency designs requiring relatively low pump power and small waveguide length. In order to realistically perform the waveguide optimization process, we propose and validate an approximate expression for the FWM efficiency, which significantly alleviates our numerical calculations. Promising waveguide designs are identified by means of an exhaustive search, altering some structural parameters. Our approach aims to optimize the waveguides for nonlinear signal-processing applications based on the FWM.

  13. Effects of Small-World Rewiring Probability and Noisy Synaptic Conductivity on Slow Waves: Cortical Network.

    Science.gov (United States)

    Tekin, Ramazan; Tagluk, Mehmet Emin

    2017-03-01

    Physiological rhythms play a critical role in the functional development of living beings. Many biological functions are executed with an interaction of rhythms produced by internal characteristics of scores of cells. While synchronized oscillations may be associated with normal brain functions, anomalies in these oscillations may cause or relate the emergence of some neurological or neuropsychological pathologies. This study was designed to investigate the effects of topological structure and synaptic conductivity noise on the spatial synchronization and temporal rhythmicity of the waves generated by cells in the network. Because of holding the ability of clustering and randomizing with change of parameters, small-world (SW) network topology was chosen. The oscillatory activity of network was tried out by manipulating an insulated SW, cortical network model whose morphology is very close to real world. According to the obtained results, it was observed that at the optimal probabilistic rates of conductivity noise and rewiring of SW, powerful synchronized oscillatory small waves are generated in relation to the internal dynamics of cells, which are in line with the network's input. These two parameters were observed to be quite effective on the excitation-inhibition balance of the network. Accordingly, it may be suggested that the topological dynamics of SW and noisy synaptic conductivity may be associated with the normal and abnormal development of neurobiological structure.

  14. Characterization of K-complexes and slow wave activity in a neural mass model.

    Directory of Open Access Journals (Sweden)

    Arne Weigenand

    2014-11-01

    Full Text Available NREM sleep is characterized by two hallmarks, namely K-complexes (KCs during sleep stage N2 and cortical slow oscillations (SOs during sleep stage N3. While the underlying dynamics on the neuronal level is well known and can be easily measured, the resulting behavior on the macroscopic population level remains unclear. On the basis of an extended neural mass model of the cortex, we suggest a new interpretation of the mechanisms responsible for the generation of KCs and SOs. As the cortex transitions from wake to deep sleep, in our model it approaches an oscillatory regime via a Hopf bifurcation. Importantly, there is a canard phenomenon arising from a homoclinic bifurcation, whose orbit determines the shape of large amplitude SOs. A KC corresponds to a single excursion along the homoclinic orbit, while SOs are noise-driven oscillations around a stable focus. The model generates both time series and spectra that strikingly resemble real electroencephalogram data and points out possible differences between the different stages of natural sleep.

  15. Asynchronous ripple oscillations between left and right hippocampi during slow-wave sleep

    Science.gov (United States)

    Villalobos, Claudio

    2017-01-01

    Spatial memory, among many other brain processes, shows hemispheric lateralization. Most of the published evidence suggests that the right hippocampus plays a leading role in the manipulation of spatial information. Concurrently in the hippocampus, memory consolidation during sleep periods is one of the key steps in the formation of newly acquired spatial memory traces. One of the most characteristic oscillatory patterns in the hippocampus are sharp-wave ripple (SWR) complexes. Within this complex, fast-field oscillations or ripples have been demonstrated to be instrumental in the memory consolidation process. Since these ripples are relevant for the consolidation of memory traces associated with spatial navigation, and this process appears to be lateralized, we hypothesize that ripple events between both hippocampi would exhibit different temporal dynamics. We tested this idea by using a modified "split-hyperdrive" that allows us to record simultaneous LFPs from both right and left hippocampi of Sprague-Dawley rats during sleep. We detected individual events and found that during sleep periods these ripples exhibited a different occurrence patterns between hemispheres. Most ripple events were synchronous between intra- rather than inter-hemispherical recordings, suggesting that ripples in the hippocampus are independently generated and locally propagated within a specific hemisphere. In this study, we propose the ripples’ lack of synchrony between left and right hippocampi as the putative physiological mechanism underlying lateralization of spatial memory. PMID:28158285

  16. Long-lasting novelty-induced neuronal reverberation during slow-wave sleep in multiple forebrain areas.

    Directory of Open Access Journals (Sweden)

    Sidarta Ribeiro

    2004-01-01

    Full Text Available The discovery of experience-dependent brain reactivation during both slow-wave (SW and rapid eye-movement (REM sleep led to the notion that the consolidation of recently acquired memory traces requires neural replay during sleep. To date, however, several observations continue to undermine this hypothesis. To address some of these objections, we investigated the effects of a transient novel experience on the long-term evolution of ongoing neuronal activity in the rat forebrain. We observed that spatiotemporal patterns of neuronal ensemble activity originally produced by the tactile exploration of novel objects recurred for up to 48 h in the cerebral cortex, hippocampus, putamen, and thalamus. This novelty-induced recurrence was characterized by low but significant correlations values. Nearly identical results were found for neuronal activity sampled when animals were moving between objects without touching them. In contrast, negligible recurrence was observed for neuronal patterns obtained when animals explored a familiar environment. While the reverberation of past patterns of neuronal activity was strongest during SW sleep, waking was correlated with a decrease of neuronal reverberation. REM sleep showed more variable results across animals. In contrast with data from hippocampal place cells, we found no evidence of time compression or expansion of neuronal reverberation in any of the sampled forebrain areas. Our results indicate that persistent experience-dependent neuronal reverberation is a general property of multiple forebrain structures. It does not consist of an exact replay of previous activity, but instead it defines a mild and consistent bias towards salient neural ensemble firing patterns. These results are compatible with a slow and progressive process of memory consolidation, reflecting novelty-related neuronal ensemble relationships that seem to be context- rather than stimulus-specific. Based on our current and previous results

  17. Slow and stored light under conditions of electromagnetically induced transparency and four wave mixing in an atomic vapor

    Science.gov (United States)

    Phillips, Nathaniel Blair

    The recent prospect of efficient, reliable, and secure quantum communication relies on the ability to coherently and reversibly map nonclassical states of light onto long-lived atomic states. A promising technique that accomplishes this employs Electromagnetically Induced Transparency (EIT), in which a strong classical control field modifies the optical properties of a weak signal field in such a way that a previously opaque medium becomes transparent to the signal field. The accompanying steep dispersion in the index of refraction allows for pulses of light to be decelerated, then stored as an atomic excitation, and later retrieved as a photonic mode. This dissertation presents the results of investigations into methods for optimizing the memory efficiency of this process in an ensemble of hot Rb atoms. We have experimentally demonstrated the effectiveness of two protocols for yielding the best memory efficiency possible at a given atomic density. Improving memory efficiency requires operation at higher optical depths, where undesired effects such as four-wave mixing (FWM) become enhanced and can spontaneously produce a new optical mode (Stokes field). We present the results of experimental and theoretical investigations of the FWM-EIT interaction under continuous-wave (cw), slow light, and stored light conditions. In particular, we provide evidence that indicates that while a Stokes field is generated upon retrieval of the signal field, any information originally encoded in a seeded Stokes field is not independently preserved during the storage process. We present a simple model that describes the propagation dynamics and provides an intuitive description of the EIT-FWM process.

  18. Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury

    Directory of Open Access Journals (Sweden)

    Ming-Xiong Huang

    2014-01-01

    Full Text Available Traumatic brain injury (TBI is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz that can be measured and localized by resting-state magnetoencephalography (MEG. In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes, our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes, blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

  19. Slow-Wave Characteristics of a Frame-Rod Structure Based on Micro-Fabricated Technology for THz Vacuum Electron Devices

    Science.gov (United States)

    Fu, Chengfang; Zhao, Bo; Yang, Yudong; Ju, Yongfeng; Yang, Dingli; Chang, Bo; He, Xiaofeng

    2016-11-01

    A simple equivalent circuit analysis of the frame-rod slow-wave structure (SWS) on dielectric substrates of a traveling-wave tube (TWT) is developed, using the quasi-TEM approximation approach for the dispersion and coupling impedance characteristics of the structure. Moreover, the obtained complex dispersion equation and coupling impedance are numerically calculated. The calculation results by our theory method agree well with the results obtained by the 3D EM simulation software HFSS. It is shown that the dispersion of the frame-rod circuit is decreased; the phase velocity is reduced and the bandwidth becomes greater, while the coupling impedance decreases after filling the dielectric materials in the frame-rod SWS. In addition, a comparison of slow-wave characteristics of this structure with a rectangular helix counterpart is made. As a planar slow-wave structure, this structure has potential applications in compact TWTs based on the micro-fabrication technology, which could be scaled to millimeter wave, even to THz frequency.

  20. Repetitive transcranial magnetic stimulation induced slow wave activity modification: A possible role in disorder of consciousness differential diagnosis?

    Science.gov (United States)

    Pisani, Laura Rosa; Naro, Antonino; Leo, Antonino; Aricò, Irene; Pisani, Francesco; Silvestri, Rosalia; Bramanti, Placido; Calabrò, Rocco Salvatore

    2015-12-15

    Slow wave activity (SWA) generation depends on cortico-thalamo-cortical loops that are disrupted in patients with chronic Disorders of Consciousness (DOC), including the Unresponsive Wakefulness Syndrome (UWS) and the Minimally Conscious State (MCS). We hypothesized that the modulation of SWA by means of a repetitive transcranial magnetic stimulation (rTMS) could reveal residual patterns of connectivity, thus supporting the DOC clinical differential diagnosis. We enrolled 10 DOC individuals who underwent a 24hh polysomnography followed by a real or sham 5Hz-rTMS over left primary motor area, and a second polysomnographic recording. A preserved sleep-wake cycle, a standard temporal progression of sleep stages, and a SWA perturbation were found in all of the MCS patients and in none of the UWS individuals, only following the real-rTMS. In conclusion, our combined approach may improve the differential diagnosis between MCS patients, who show a partial preservation of cortical plasticity, and UWS individuals, who lack such properties.

  1. Human longevity is associated with regular sleep patterns, maintenance of slow wave sleep, and favorable lipid profile

    Science.gov (United States)

    Mazzotti, Diego Robles; Guindalini, Camila; Moraes, Walter André dos Santos; Andersen, Monica Levy; Cendoroglo, Maysa Seabra; Ramos, Luiz Roberto; Tufik, Sergio

    2014-01-01

    Some individuals are able to successfully reach very old ages, reflecting higher adaptation against age-associated effects. Sleep is one of the processes deeply affected by aging; however few studies evaluating sleep in long-lived individuals (aged over 85) have been reported to date. The aim of this study was to characterize the sleep patterns and biochemical profile of oldest old individuals (N = 10, age 85–105 years old) and compare them to young adults (N = 15, age 20–30 years old) and older adults (N = 13, age 60–70 years old). All subjects underwent full-night polysomnography, 1-week of actigraphic recording and peripheral blood collection. Sleep electroencephalogram spectral analysis was also performed. The oldest old individuals showed lower sleep efficiency and REM sleep when compared to the older adults, while stage N3 percentage and delta power were similar across the groups. Oldest old individuals maintained strictly regular sleep-wake schedules and also presented higher HDL-cholesterol and lower triglyceride levels than older adults. The present study revealed novel data regarding specific sleep patterns and maintenance of slow wave sleep in the oldest old group. Taken together with the favorable lipid profile, these results contribute with evidence to the importance of sleep and lipid metabolism regulation in the maintenance of longevity in humans. PMID:25009494

  2. Slow wave sleep during a daytime nap is necessary for protection from subsequent interference and long-term retention.

    Science.gov (United States)

    Alger, Sara E; Lau, Hiuyan; Fishbein, William

    2012-09-01

    While it is now generally accepted that sleep facilitates the processing of newly acquired declarative information, questions still remain as to the type and length of sleep necessary to best benefit declarative memories. A better understanding could lend support in one direction or another as to the much-debated role of sleep, be it passive, permissive, or active, in memory processing. The present study employed a napping paradigm and compared performance on a bimodal paired-associates task of those who obtained a 10-min nap, containing only Stages 1 and 2 sleep, to those whose nap contained slow-wave sleep (SWS) and rapid eye movement (REM) sleep (60-min nap), as well as to subjects who remained awake. Measurements were obtained for baseline performance at training, after a sleep/no sleep interval for short-term retention, after a subsequent stimulus-related interference task, and again after a weeklong retention period. While all groups learned the information similarly, both nap groups performed better than the Wake group when examining short-term retention, approximately 1.5h after training (10-min p=.052, 60-min p=.002). However, performance benefits seen in the 10-min nap group proved to be temporary. Performance after a stimulus-related interference task revealed significantly better memory retention in the 60-min nap group, with interference disrupting the memory trace far less than both the Wake and 10-min nap groups (pconsolidation of learned bimodal paired-associates, supported by theories such as the Standard Theory of Consolidation as well as the Synaptic Homeostasis Hypothesis.

  3. Theta-rhythmic drive between medial septum and hippocampus in slow-wave sleep and microarousal: a Granger causality analysis

    Science.gov (United States)

    Kang, D.; Ding, M.; Topchiy, I.; Shifflett, L.

    2015-01-01

    Medial septum (MS) plays a critical role in controlling the electrical activity of the hippocampus (HIPP). In particular, theta-rhythmic burst firing of MS neurons is thought to drive lasting HIPP theta oscillations in rats during waking motor activity and REM sleep. Less is known about MS-HIPP interactions in nontheta states such as non-REM sleep, in which HIPP theta oscillations are absent but theta-rhythmic burst firing in subsets of MS neurons is preserved. The present study used Granger causality (GC) to examine the interaction patterns between MS and HIPP in slow-wave sleep (SWS, a nontheta state) and during its short interruptions called microarousals (a transient theta state). We found that during SWS, while GC revealed a unidirectional MS→HIPP influence over a wide frequency band (2–12 Hz, maximum: ∼8 Hz), there was no theta peak in the hippocampal power spectra, indicating a lack of theta activity in HIPP. In contrast, during microarousals, theta peaks were seen in both MS and HIPP power spectra and were accompanied by bidirectional GC with MS→HIPP and HIPP→MS theta drives being of equal magnitude. Thus GC in a nontheta state (SWS) vs. a theta state (microarousal) primarily differed in the level of HIPP→MS. The present findings suggest a modification of our understanding of the role of MS as the theta generator in two regards. First, a MS→HIPP theta drive does not necessarily induce theta field oscillations in the hippocampus, as found in SWS. Second, HIPP theta oscillations entail bidirectional theta-rhythmic interactions between MS and HIPP. PMID:26354315

  4. Enhanced slow-wave EEG activity and thermoregulatory impairment following the inhibition of the lateral hypothalamus in the rat.

    Directory of Open Access Journals (Sweden)

    Matteo Cerri

    Full Text Available Neurons within the lateral hypothalamus (LH are thought to be able to evoke behavioural responses that are coordinated with an adequate level of autonomic activity. Recently, the acute pharmacological inhibition of LH has been shown to depress wakefulness and promote NREM sleep, while suppressing REM sleep. These effects have been suggested to be the consequence of the inhibition of specific neuronal populations within the LH, i.e. the orexin and the MCH neurons, respectively. However, the interpretation of these results is limited by the lack of quantitative analysis of the electroencephalographic (EEG activity that is critical for the assessment of NREM sleep quality and the presence of aborted NREM-to-REM sleep transitions. Furthermore, the lack of evaluation of the autonomic and thermoregulatory effects of the treatment does not exclude the possibility that the wake-sleep changes are merely the consequence of the autonomic, in particular thermoregulatory, changes that may follow the inhibition of LH neurons. In the present study, the EEG and autonomic/thermoregulatory effects of a prolonged LH inhibition provoked by the repeated local delivery of the GABAA agonist muscimol were studied in rats kept at thermoneutral (24°C and at a low (10°C ambient temperature (Ta, a condition which is known to depress sleep occurrence. Here we show that: 1 at both Tas, LH inhibition promoted a peculiar and sustained bout of NREM sleep characterized by an enhancement of slow-wave activity with no NREM-to-REM sleep transitions; 2 LH inhibition caused a marked transitory decrease in brain temperature at Ta 10°C, but not at Ta 24°C, suggesting that sleep changes induced by LH inhibition at thermoneutrality are not caused by a thermoregulatory impairment. These changes are far different from those observed after the short-term selective inhibition of either orexin or MCH neurons, suggesting that other LH neurons are involved in sleep-wake modulation.

  5. Research the dynamical characteristics of slow deformation waves as a rock massif response to explosions during its outworking

    Science.gov (United States)

    Hachay, Olga; Khachay, Oleg; Shipeev, Oleg

    2015-04-01

    mine to estimate the changing state of the rock burst in the massif by its outworking. As a result we have selected a typical morphology of massif response phase trajectories, which were locally, over time, in a stable state: on the phase plane the local area presented as a ball of twisted trajectories with some not far removed points from the ball, which had not exceeded energy of more than 105 joules. For some time intervals those removed points exceeded 105 joules, achieving 106 joules and even 109 joules (Hachay et al., 2010). Introduction of the additional velocity parameter of slow deformation wave propagation allowed us, with the use of phase diagrams, to identify the hierarchic structure. Further, we can use that information for the modelling and interpretation of seismic and deformation waves in hierarchic structures (Hachay et al., 2012). That method can be useful in building-up an understanding of the resonance outshooting of catastrophic dynamic events and prevent these events. References 1.Chulichkov A. (2003) Mathematical models of nonlinear dynamics. Moscow: Phismatlit. 294p. 2.Hachay O., Khachay O.Yu., Klimko V., et al. (2010) Reflection of synergetic features of rock massif state under the man-caused influence from the data of a seismological catalogue. Mining Information-Analytic Bulletin, Moscow, Mining book, 6, pp.259-271. 3.Hachay O., Khachay A.Yu. (2012) Research of stress-deforming state of hierarchic medium. Proceedings of the Third Tectonics and Physics Conference at the Institute of the Physics of the Earth 8-12 October 2012, Moscow, IFZ RAS, pp.114-117. 4.Kurlenja M., Oparin V., Vostrikov V. (1993) About forming elastic wave trains by impulse excitation of block medium. Waves of pendulum type Uμ. DAN USSR, V.133, 4, pp.475-481. 5.Naimark Yu., Landa P. (2009). Stochastic and chaotic oscillations. Moscow, Knigniy dom ,'LIBROKOM', 424 p. 7.Oparin V., Vostrikov V., Tapsiev A. et al. (2006) About one kinematic criterion of forecasting of the

  6. A proposal for enhancing four-wave mixing in slow light engineered photonic crystal waveguides and its application to optical regeneration.

    Science.gov (United States)

    Ebnali-Heidari, M; Monat, C; Grillet, C; Moravvej-Farshi, M K

    2009-09-28

    In this paper, we investigate both analytically and numerically four-wave mixing (FWM) in short (80 microm) dispersion engineered slow light photonic crystal waveguides. We demonstrate that both a larger FWM conversion efficiency and an increased FWM bandwidth (approximately 10 nm) can be achieved in these waveguides as compared to dispersive PhC waveguides. This improvement is achieved through the net slow light enhancement of the FWM efficiency (almost 30dB as compared to a fast nanowire of similar length), even in the presence of slow light increased linear and nonlinear losses, and the suitable dispersion profile of these waveguides. We show how such improved FWM operation can be advantageously exploited for designing a compact 2R and 3R regenerator with the appropriate nonlinear power transfer function.

  7. Bowel Incontinence

    Science.gov (United States)

    ... women and older adults. It is not a normal part of aging. Causes include Constipation Damage to muscles or nerves of the anus and rectum Diarrhea Pelvic support problems Treatments include changes in diet, medicines, bowel training, or surgery. NIH: ...

  8. 一种新型微带曲折线慢波结构的设计%Design of a New Microstrip Meander-Line Slow Wave Structure

    Institute of Scientific and Technical Information of China (English)

    陈常婷; 宫玉彬; 沈飞; 魏彦玉; 王文祥

    2011-01-01

    设计了一种新型微带曲折线慢波结构,该结构采用双介质杆支撑式的V型平面曲折线慢波电路.利用电磁场仿真软件HFSS对这种新型结构和传统微带曲折线慢波结构进行了分析比较,研究结果表明,新型微带曲折线慢波结构在不改变色散强弱的情况下,工作频段向高频端拓展且耦合阻抗有了很大提高,可以更好地工作在短毫米波段.并仿真分析了结构参数对高频特性的影响,所获得的仿真结果为器件的粒子模拟及计算慢波结构的工作效率奠定了基础.%A new microstrip meander-line slow wave structure was designed, which uses the V-type plane meander-line slow wave circuit with twin dielectric-strips.The performances of the new microstrip meander-line slow wave structure and the traditional meander-line slow wave structure were compared by using of the electromagnetic simulation software HFSS.The effects of different structural parameters on the new structure were analyzed.The simulation results show that the new microstrip meander-line slow wave structure has a similar dispersion characteristic with the traditional structure, and the center frequency expands to the higher frequency, and the coupling impedance is greatly improved.Hence the new structure can work much better in millimeter wave band.The results lay a good foundation for particle-in-cell (PIC) simulation and efficiency caculation.

  9. Simulation of High-frequency Characterisdtics of Periodic Slow-wave Structure%周期慢波结构高频特性的仿真研究

    Institute of Scientific and Technical Information of China (English)

    耿力东; 郝世荣; 杨宇

    2009-01-01

    由于理论方法数值计算量大以及与实际复杂结构差别大,同时实验测试方法误差大、且高次模难激励.针对这些算法的缺点,采用理论和数值模拟结合方法从而克服上述方法不足,仿真研究了圆柱载膜波导慢波结构的色散特性,其结果和理论计算结果模拟比较,二者吻合.研究表明圆柱载膜波导慢波结构的谐振频率(同一模式下)与载膜半径成正比、与周期成反比;同时表明上述方法计算简单,省去了繁琐的求解方程过程.最后给出各个模式电场分布,对研究分析束波互作用提供依据.%The peper analyses dispersion characteristic of column wave -guide with a slow- wave ,because there are differences between the experiment and theoretical methods. In this paper, the theory is combined with numerical simulation to study the High - frqueency dispersion characteristic of column wave - guide with a slow wave. Comparing the result of theory with the result of numerical simulation, two results are identical. The rsimulation result indicates that the harmonic frequency increases with the radius, and decreases with periodi of slow - wave structure.

  10. Encephalopathy with Electrical Status Epilepticus in Slow Wave Sleep – a review with an emphasis on regional (perisylvian aspects

    Directory of Open Access Journals (Sweden)

    Halász Peter

    2014-12-01

    Full Text Available Aim. The aim of this article is to review criticaly the Electrical Status Epilepticus in Slow Sleep (ESES phenomenon from a neurophysiological mechanisms aspect as well as terminological and classification issues.

  11. Design of Coplanar Waveguide Interdigital Slow Wave Delay Line%共面波导交指慢波延迟线设计

    Institute of Scientific and Technical Information of China (English)

    梅亮; 张华; 王继财

    2012-01-01

    This paper presents a design of coplanar waveguide interdigital slow wave delay line, describes the theory of slow wave delay line, and obtains optimized parameters of delay line by electromagnetic simulating software. The delay line which works on X wave band, has 7λ (about 700 ps) delay on center frequency and insertion loss of 2. 0 dB. The measured results are in good agreement with the simulated ones.%提出了一种共面波导交指慢波延迟线的设计,介绍了慢波延迟线工作原理,利用电磁仿真软件优化得到了延迟线的各项参数.该延迟线工作在x波段,具有中心频率7λ(约700 ps)的延迟,延迟线的插入损耗约2.0 dB.延迟线的实测与仿真结果吻合较好.

  12. Fast- and slow-wave heating of ion cyclotron range of frequencies in the Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Mutoh, T.; Kumazawa, R.; Seki, T. [and others

    2000-11-01

    Wave-heating at the fundamental ion-cyclotron frequency was applied to a hydrogen plasma in the Large Helical Device (LHD) over a range of plasma densities from 0.2-8x10{sup 19} m{sup -3}. Substantial heating was observed for all densities. In the low-density plasma (less than 0.4x10{sup 19} m{sup -3}) ion-cyclotron-wave (shear Alfven wave) heating was effective. For high-density plasmas, a fast-wave should be excited, and in this case also, effective heating was observed with the presence of the NBI beam component. The wave damping mechanism may be attributed to the finite gyro-radius effect on beam ions by the right-handed polarized wave. The experimental results were compared with an analysis using the full-wave code. The heating performance was a little worse than that of the usual two-ion hybrid-heating mode. (author)

  13. Short Bowel Syndrome

    Science.gov (United States)

    ... System & How it Works Digestive Diseases A-Z Short Bowel Syndrome What is Short Bowel Syndrome Short bowel syndrome is a group of problems ... between the stomach and large intestine. What causes Short Bowel Syndrome? The main cause of short bowel syndrome is ...

  14. Differing Event-Related Patterns of Gamma-Band Power in Brain Waves of Fast- and Slow-Reacting Subjects

    Science.gov (United States)

    1994-05-01

    Wilhelm Wundt proposed that there are two types of subjects in sim- ple RT experiments: fast-reacting subjects, who respond before they fully...quickly as possible to auditory stimuli. This result appears to confirm long-standing speculations of Wundt that fast- and slow-reacting subjects...accord with the hypothesis of Wundt and others that slower ("sensorial") responders wait to fully perceive a stimulus and then react to their perception

  15. Magnetoencephalography Slow-Wave Detection in Patients with Mild Traumatic Brain Injury and Ongoing Symptoms Correlated with Long-Term Neuropsychological Outcome.

    Science.gov (United States)

    Robb Swan, Ashley; Nichols, Sharon; Drake, Angela; Angeles, AnneMarie; Diwakar, Mithun; Song, Tao; Lee, Roland R; Huang, Ming-Xiong

    2015-10-01

    Mild traumatic brain injury (mTBI) is common in the United States, accounting for as many as 75-80% of all TBIs. It is recognized as a significant public health concern, but there are ongoing controversies regarding the etiology of persistent symptoms post-mTBI. This constellation of nonspecific symptoms is referred to as postconcussive syndrome (PCS). The present study combined results from magnetoencephalography (MEG) and cognitive assessment to examine group differences and relationships between brain activity and cognitive performance in 31 military and civilian individuals with a history of mTBI+PCS and 33 matched healthy control subjects. An operator-free analysis was used for MEG data to increase reliability of the technique. Subjects completed a comprehensive neuropsychological assessment, and measures of abnormal slow-wave activity from MEG were collected. Results demonstrated significant group differences on measures of executive functioning and processing speed. In addition, significant correlations between slow-wave activity on MEG and patterns of cognitive functioning were found in cortical areas, consistent with cognitive impairments on exams. Results provide more objective evidence that there may be subtle changes to the neurobiological integrity of the brain that can be detected by MEG. Further, these findings suggest that these abnormalities are associated with cognitive outcomes and may account, at least in part, for long-term PCS in those who have sustained an mTBI.

  16. Bowel disease

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    2008069 The application of Montreal classification in inflammatory bowel disease. YANG Chuanhua(杨川华), et al. Renji Hosp, Shanghai Instit, Shanghai Jiaotong Univ Med Coll, Shanghai 200001. Chin J Intern Med 2008;47(1):7-10. Objective To investigate the clinical features of Crohn′s disease (CD) and ulcerative colitis (UC) according to the Montreal classification. Methods The clinical data of 110 cases of CD or UC were reviewed. The age at

  17. Small bowel bacterial overgrowth

    Science.gov (United States)

    ... scleroderma . Immunodeficiency such as AIDS or immunoglobulin deficiency. Short bowel syndrome caused by surgical removal of the small intestine. ... obstruction Irritable bowel syndrome Liver disease Osteoporosis - overview Short bowel syndrome Toxic megacolon Vagina Review Date 5/11/2016 ...

  18. Nonlinear phase shifts of modulated light waves with slow and superluminal group delay in stimulated Brillouin scattering.

    Science.gov (United States)

    Arditi, Tal; Granot, Er'el; Sternklar, Shmuel

    2007-09-15

    Brillouin amplification with counterpropagating modulated pump and Stokes light leads to nonlinear modulation-phase shifts of the interacting intensity waves. This is due to a partial transformation of the nonmodulated light component at the input into modulated light at the output as a result of a mixing process with the counterpropagating modulated component of the pump and results in an advance or delay of the input modulation. This occurs for interactions over less than half of a modulation wavelength. Milliwatts of power in a kilometer of standard single-mode fiber give significant tunability of the modulation phase.

  19. Spatial proximity effects on the excitation of sheath RF voltages by evanescent slow waves in the ion cyclotron range of frequencies

    Science.gov (United States)

    Colas, Laurent; Lu, Ling-Feng; Křivská, Alena; Jacquot, Jonathan; Hillairet, Julien; Helou, Walid; Goniche, Marc; Heuraux, Stéphane; Faudot, Eric

    2017-02-01

    We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the near RF parallel electric field E ∥ emitted by ion cyclotron (IC) wave launchers. We use a simple model of slow wave (SW) evanescence coupled with direct current (DC) plasma biasing via sheath boundary conditions in a 3D parallelepiped filled with homogeneous cold magnetized plasma. Within a ‘wide-sheath’ asymptotic regime, valid for large-amplitude near RF fields, the RF part of this simple RF  +  DC model becomes linear: the sheath oscillating voltage V RF at open field line boundaries can be re-expressed as a linear combination of individual contributions by every emitting point in the input field map. SW evanescence makes individual contributions all the larger as the wave emission point is located closer to the sheath walls. The decay of |V RF| with the emission point/sheath poloidal distance involves the transverse SW evanescence length and the radial protrusion depth of lateral boundaries. The decay of |V RF| with the emitter/sheath parallel distance is quantified as a function of the parallel SW evanescence length and the parallel connection length of open magnetic field lines. For realistic geometries and target SOL plasmas, poloidal decay occurs over a few centimeters. Typical parallel decay lengths for |V RF| are found to be smaller than IC antenna parallel extension. Oscillating sheath voltages at IC antenna side limiters are therefore mainly sensitive to E ∥ emission by active or passive conducting elements near these limiters, as suggested by recent experimental observations. Parallel proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel antisymmetry of the radiated field map. They could finally justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

  20. Enhanced slow wave sleep and improved sleep maintenance after gaboxadol administration during seven nights of exposure to a traffic noise model of transient insomnia.

    Science.gov (United States)

    Dijk, D-J; Stanley, N; Lundahl, J; Groeger, J A; Legters, A; Trap Huusom, A K; Deacon, S

    2012-08-01

    Slow wave sleep (SWS) has been reported to correlate with sleep maintenance, but whether pharmacological enhancement of SWS also leads to improved sleep maintenance is not known. Here we evaluate the time-course of the effects of gaboxadol, an extra-synaptic gamma-aminobutyric acid (GABA) agonist, on SWS, sleep maintenance, and other sleep measures in a traffic noise model of transient insomnia. After a placebo run-in, 101 healthy subjects (20-78 y) were randomized to gaboxadol (n = 50; 15 mg in subjects <65 y and 10 mg in subjects ≥65 y) or placebo (n = 51) for 7 nights (N1-N7). The model caused some disruption of sleep initiation and maintenance, with greatest effects on N1. Compared with placebo, gaboxadol increased SWS and slow wave activity throughout N1 to N7 (p < 0.05). Gaboxadol reduced latency to persistent sleep overall (N1-N7) by 4.5 min and on N1 by 11 min (both p < 0.05). Gaboxadol increased total sleep time (TST) overall by 16 min (p < 0.001) and on N1 by 38 min (p < 0.0001). Under gaboxadol, wakefulness after sleep onset was reduced by 11 min overall (p < 0.01) and by 29 min on N1 (p < 0.0001), and poly-somnographic awakenings were reduced on N1 (p < 0.05). Gaboxadol reduced self-reported sleep onset latency overall and on N1 (both p < 0.05) and increased self-reported TST overall (p < 0.05) and on N1 (p < 0.01). Subjective sleep quality improved overall (p < 0.01) and on N1 (p < 0.0001). Increases in SWS correlated with objective and subjective measures of sleep maintenance and subjective sleep quality under placebo and gaboxadol (p < 0.05). Gaboxadol enhanced SWS and reduced the disruptive effects of noise on sleep initiation and maintenance.

  1. Slow Heartbeat

    Science.gov (United States)

    ... per minute. The heartbeat is controlled by an electrical system that signals the heart muscle to contract, or “squeeze,” pumping blood to the rest of the body. Bradycardia happens when the system slows or blocks ...

  2. Transabdominal Ultrasonography of the Small Bowel

    Directory of Open Access Journals (Sweden)

    Rudolf Kralik

    2013-01-01

    Full Text Available In the era of double balloon enteroscopy, capsule endoscopy, CT, and MRI enterography is transabdominal ultrasonography (TUS underestimated method for evaluation of small bowel pathology. As often initial imagine method in abdominal complaints, nowadays has TUS much better diagnostic potential than two decades ago. High-resolution ultrasound probes with harmonic imaging significantly improve resolution of bowel wall in real time, with possibility to asses bowel peristalsis. Color flow doppler enables evaluation of intramural bowel vascularisation, pulse wave doppler helps to quantificate flow in coeliac and superior mesenteric arteries. Small intestine contrast ultrasonography with oral contrast fluid, as well as contrast enhanced ultrasonography with intravenous microbubble contrast also improves small bowel imaging. We present a review of small intestine pathology that should be detected during ultrasound examinations, discuss technical requirements, advantages and limitations of TUS, typical ultrasound signs of Crohn's disease, ileus, celiac disease, intussusception, infectious enteritis, tumours, ischemic and haemorrhagic conditions of small bowel. In the hands of experienced investigator, despite some significant limitations(obesity, meteorism, is transabdominal ultrasonography reliable, noninvasive and inexpensive alternative method to computerised tomography (CT and magnetic resonance imaging (MRI in small bowel examination.

  3. Accidental Bowel Leakage

    Science.gov (United States)

    ... I do to help treat accidental bowel leakage? Kegel exercises strengthen the muscles that surround the openings ... bowels that may cause cramping, diarrhea, or constipation. Kegel Exercises: Pelvic muscle exercises that assist in bladder ...

  4. Ocular-motor profile and effects of memantine in a familial form of adult cerebellar ataxia with slow saccades and square wave saccadic intrusions.

    Directory of Open Access Journals (Sweden)

    Francesca Rosini

    Full Text Available Fixation instability due to saccadic intrusions is a feature of autosomal recessive spinocerebellar ataxias, and includes square wave intrusions (SWI and macrosaccadic oscillations (MSO. A recent report suggested that the non-competitive antagonist of NMDA receptors, memantine, could decrease MSO and improve fixation in patients with spinocerebellar ataxia with saccadic intrusions (SCASI. We similarly tested two sisters, respectively of 58 and 60 years, with an unrecognized form of recessive, adult-onset cerebellar ataxia, peripheral neuropathy and slow saccades, who showed prominent SWI and also complained with difficulty in reading. We tested horizontal visually guided saccades (10°-18° and three minutes of steady fixation in each patient and in thirty healthy controls. Both patients showed a significant reduction of peak and mean velocity compared with control subjects. Large SWI interrupting steady fixation were prominent during steady fixation and especially following visually guided saccades. Eye movements were recorded before and during the treatment with memantine, 20 mg/daily for 6 months. The treatment with memantine reduced both the magnitude and frequency of SWI (the former significantly, but did not modified neurological conditions or saccade parameters. Thus, our report suggests that memantine may have some general suppressive effect on saccadic intrusions, including both SWI and MSO, thereby restoring the capacity of reading and visual attention in these and in other recessive forms of ataxia, including Friedreich's, in which saccadic intrusions are prominent.

  5. Essential roles of GABA transporter-1 in controlling rapid eye movement sleep and in increased slow wave activity after sleep deprivation.

    Directory of Open Access Journals (Sweden)

    Xin-Hong Xu

    Full Text Available GABA is the major inhibitory neurotransmitter in the mammalian central nervous system that has been strongly implicated in the regulation of sleep. GABA transporter subtype 1 (GAT1 constructs high affinity reuptake sites for GABA and regulates GABAergic transmission in the brain. However, the role of GAT1 in sleep-wake regulation remains elusive. In the current study, we characterized the spontaneous sleep-wake cycle and responses to sleep deprivation in GAT1 knock-out (KO mice. GAT1 KO mice exhibited dominant theta-activity and a remarkable reduction of EEG power in low frequencies across all vigilance stages. Under baseline conditions, spontaneous rapid eye movement (REM sleep of KO mice was elevated both during the light and dark periods, and non-REM (NREM sleep was reduced during the light period only. KO mice also showed more state transitions from NREM to REM sleep and from REM sleep to wakefulness, as well as more number of REM and NREM sleep bouts than WT mice. During the dark period, KO mice exhibited more REM sleep bouts only. Six hours of sleep deprivation induced rebound increases in NREM and REM sleep in both genotypes. However, slow wave activity, the intensity component of NREM sleep was briefly elevated in WT mice but remained completely unchanged in KO mice, compared with their respective baselines. These results indicate that GAT1 plays a critical role in the regulation of REM sleep and homeostasis of NREM sleep.

  6. Essential roles of GABA transporter-1 in controlling rapid eye movement sleep and in increased slow wave activity after sleep deprivation.

    Science.gov (United States)

    Xu, Xin-Hong; Qu, Wei-Min; Bian, Min-Juan; Huang, Fang; Fei, Jian; Urade, Yoshihiro; Huang, Zhi-Li

    2013-01-01

    GABA is the major inhibitory neurotransmitter in the mammalian central nervous system that has been strongly implicated in the regulation of sleep. GABA transporter subtype 1 (GAT1) constructs high affinity reuptake sites for GABA and regulates GABAergic transmission in the brain. However, the role of GAT1 in sleep-wake regulation remains elusive. In the current study, we characterized the spontaneous sleep-wake cycle and responses to sleep deprivation in GAT1 knock-out (KO) mice. GAT1 KO mice exhibited dominant theta-activity and a remarkable reduction of EEG power in low frequencies across all vigilance stages. Under baseline conditions, spontaneous rapid eye movement (REM) sleep of KO mice was elevated both during the light and dark periods, and non-REM (NREM) sleep was reduced during the light period only. KO mice also showed more state transitions from NREM to REM sleep and from REM sleep to wakefulness, as well as more number of REM and NREM sleep bouts than WT mice. During the dark period, KO mice exhibited more REM sleep bouts only. Six hours of sleep deprivation induced rebound increases in NREM and REM sleep in both genotypes. However, slow wave activity, the intensity component of NREM sleep was briefly elevated in WT mice but remained completely unchanged in KO mice, compared with their respective baselines. These results indicate that GAT1 plays a critical role in the regulation of REM sleep and homeostasis of NREM sleep.

  7. Self-excitation of microwave oscillations in plasma-assisted slow-wave oscillators by an electron beam with a movable focus.

    Science.gov (United States)

    Bliokh, Yu P; Nusinovich, G S; Shkvarunets, A G; Carmel, Y

    2004-10-01

    Plasma-assisted slow-wave oscillators (pasotrons) operate without external magnetic fields, which makes these devices quite compact and lightweight. Beam focusing in pasotrons is provided by ions, which appear in the device due to the impact ionization of a neutral gas by beam electrons. Typically, the ionization time is on the order of the rise time of the beam current. This means that, during the rise of the current, beam focusing by ions becomes stronger. Correspondingly, a beam of electrons, which was initially diverging radially due to the self-electric field, starts to be focused by ions, and this focus moves towards the gun as the ion density increases. This feature makes the self-excitation of electromagnetic (em) oscillations in pasotrons quite different from practically all other microwave sources where em oscillations are excited by a stationary electron beam. The process of self-excitation of em oscillations has been studied both theoretically and experimentally. It is shown that in pasotrons, during the beam current rise the amount of current entering the interaction space and the beam coupling to the em field vary. As a result, the self-excitation can proceed faster than in conventional microwave sources with similar operating parameters such as the operating frequency, cavity quality-factor and the beam current and voltage.

  8. Associations between prospective symptom changes and slow-wave activity in patients with Internet gaming disorder: A resting-state EEG study.

    Science.gov (United States)

    Kim, Yeon Jin; Lee, Jun-Young; Oh, Sohee; Park, Minkyung; Jung, Hee Yeon; Sohn, Bo Kyung; Choi, Sam-Wook; Kim, Dai Jin; Choi, Jung-Seok

    2017-02-01

    The identification of the predictive factors and biological markers associated with treatment-related changes in the symptoms of Internet gaming disorder (IGD) may provide a better understanding of the pathophysiology underlying this condition. Thus, the present study aimed to identify neurophysiological markers associated with symptom changes in IGD patients and to identify factors that may predict symptom improvements following outpatient treatment with pharmacotherapy. The present study included 20 IGD patients (mean age: 22.71 ± 5.47 years) and 29 healthy control subjects (mean age: 23.97 ± 4.36 years); all IGD patients completed a 6-month outpatient management program that included pharmacotherapy with selective serotonin reuptake inhibitors. Resting-state electroencephalography scans were acquired prior to and after treatment, and the primary treatment outcome was changes in scores on Young's Internet Addiction Test (IAT) from pre- to posttreatment. IGD patients showed increased resting-state electroencephalography activity in the delta and theta bands at baseline, but the increased delta band activity was normalized after 6 months of treatment and was significantly correlated with improvements in IGD symptoms. Additionally, higher absolute theta activity at baseline predicted a greater possibility of improvement in addiction symptoms following treatment, even after adjusting for the effects of depressive or anxiety symptoms. The present findings demonstrated that increased slow-wave activity represented a state neurophysiological marker in IGD patients and suggested that increased theta activity at baseline may be a favorable prognostic marker for this population.

  9. Are Your Bowels Moving?

    Science.gov (United States)

    ... Happens in the Operating Room? Are Your Bowels Moving? KidsHealth > For Kids > Are Your Bowels Moving? A A A What's in this article? What's ... to Know? en español ¿Se mueven tus intestinos? Moving your bowels means to poop. If you said " ...

  10. Randomised clinical trial of the effects of prolonged-release melatonin, temazepam and zolpidem on slow-wave activity during sleep in healthy people.

    Science.gov (United States)

    Arbon, Emma L; Knurowska, Malgorzata; Dijk, Derk-Jan

    2015-07-01

    Current pharmacological treatments for insomnia include benzodiazepine and non-benzodiazepine hypnotics targeting γ-aminobutyric acid (GABA)A receptors, as well as agonists of the melatonin receptors MT1 and MT2. Melatonin, temazepam and zolpidem are thought to exert their effect through different mechanisms of action, but whether this leads to differential effects on electroencephalogram (EEG) power spectra during sleep in middle-aged people is currently not known. To establish whether the effects of prolonged-release melatonin (2 mg) on the nocturnal sleep EEG are different to those of temazepam (20 mg) and zolpidem (10 mg). Sixteen healthy men and women aged 55-64 years participated in a double-blind, placebo-controlled, four-way cross-over trial. Nocturnal sleep was assessed with polysomnography and spectral analysis of the EEG. The effects of single oral doses of prolonged-release melatonin, temazepam and zolpidem on EEG slow-wave activity (SWA, 0.75-4.5 Hz) and other frequencies during nocturnal non-rapid eye movement (NREM) sleep were compared. In an entire night analysis prolonged-release melatonin did not affect SWA, whereas temazepam and zolpidem significantly reduced SWA compared with placebo. Temazepam significantly reduced SWA compared with prolonged-release melatonin. Prolonged-release melatonin only reduced SWA during the first third of the night compared with placebo. These data show that the effects of prolonged-release melatonin on the nocturnal sleep EEG are minor and are different from those of temazepam and zolpidem; this is likely due to the different mechanisms of action of the medications.

  11. Role of calcium stores and membrane voltage in the generation of slow wave action potentials in guinea-pig gastric pylorus.

    Science.gov (United States)

    van Helden, D F; Imtiaz, M S; Nurgaliyeva, K; von der Weid, P; Dosen, P J

    2000-04-01

    1. Intracellular recordings made in single bundle strips of a visceral smooth muscle revealed rhythmic spontaneous membrane depolarizations termed slow waves (SWs). These exhibited 'pacemaker' and 'regenerative' components composed of summations of more elementary events termed spontaneous transient depolarizations (STDs). 2. STDs and SWs persisted in the presence of tetrodotoxin, nifedipine and ryanodine, and upon brief exposure to Ca2+-free Cd2+-containing solutions; they were enhanced by ACh and blocked by BAPTA AM, cyclopiazonic acid and caffeine. 3. SWs were also inhibited in heparin-loaded strips. SWs were observed over a wide range of membrane potentials (e.g. -80 to -45 mV) with increased frequencies at more depolarized potentials. 4. Regular spontaneous SW activity in this preparation began after 1-3 h superfusion of the tissue with physiological saline following the dissection procedure. Membrane depolarization applied before the onset of this activity induced bursts of STD-like events (termed the 'initial' response) which, when larger than threshold levels initiated regenerative responses. The combined initial-regenerative waveform was termed the SW-like action potential. 5. Voltage-induced responses exhibited large variable latencies (typical range 0.3-4 s), refractory periods of approximately 11 s and a pharmacology that was indistinguishable from those of STDs and spontaneous SWs. 6. The data indicate that SWs arise through more elementary inositol 1,4,5-trisphosphate (IP3) receptor-induced Ca2+ release events which rhythmically synchronize to trigger regenerative Ca2+ release and induce inward current across the plasmalemma. The finding that action potentials, which were indistinguishable from SWs, could be evoked by depolarization suggests that membrane potential modulates IP3 production. Voltage feedback on intracellular IP3-sensitive Ca2+ release is likely to have a major influence on the generation and propagation of SWs.

  12. Functional bowel disease

    DEFF Research Database (Denmark)

    Rumessen, J J; Gudmand-Høyer, E

    1988-01-01

    Twenty-five patients with functional bowel disease were given fructose, sorbitol, fructose-sorbitol mixtures, and sucrose. The occurrence of malabsorption was evaluated by means of hydrogen breath tests and the gastrointestinal symptoms, if any, were recorded. One patient could not be evaluated...... with functional bowel disease. The findings may have direct influence on the dietary guidance given to a major group of patients with functional bowel disease and may make it possible to define separate entities in this disease complex....

  13. Physiologic effects of bowel preparation

    DEFF Research Database (Denmark)

    Holte, Kathrine; Nielsen, Kristine Grubbe; Madsen, Jan Lysgård;

    2004-01-01

    as increased phosphate and urea concentrations, whereas calcium and potassium concentrations decreased significantly after bowel preparation. No differences in plasma or extracellular volumes were seen. Orthostatic tolerance and balance function did not change after bowel preparation. CONCLUSIONS: Bowel...

  14. Irritable bowel syndrome

    Science.gov (United States)

    ... or more. The main symptoms include: Abdominal pain Gas Fullness Bloating Change in bowel habits Pain and other symptoms will often be reduced or go away after a bowel movement. Symptoms may flare up when there is a change in the ...

  15. Pediatric inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Karen A Diefenbach; Christopher K Breuer

    2006-01-01

    Inflammatory bowel disease is an important cause of gastrointestinal pathology in children and adolescents.The incidence of pediatric inflammatory bowel disease is increasing; therefore, it is important for the clinician to be aware of the presentation of this disease in the pediatric population. Laboratory tests, radiology studies,and endoscopic procedures are helpful in diagnosing inflammatory bowel disease and differentiating between Crohn's disease and ulcerative colitis. Once diagnosed,the goal of medical management is to induce remission of disease while minimizing the side effects of the medication. Specific attention needs to be paid to achieving normal growth in this susceptible population.Surgical management is usually indicated for failure of medical management, complication, or malignancy.Algorithms for diagnostic evaluation and treatment of pediatric inflammatory bowel disease are presented.The specific psychosocial issues facing these patients are also discussed in this review as are the future goals of research in the complex problem of pediatric inflammatory bowel disease.

  16. Numerical Analysis of High-Frequency Characteristics of Rectangular Helical Slow-Wave Circuits%矩形螺旋线慢波电路高频特性的数值分析

    Institute of Scientific and Technical Information of China (English)

    付成芳; 魏彦玉; 宫玉彬; 王文祥

    2009-01-01

    The high-frequency characteristics,including its dispersion characteristics and its coupling impedance,of rectangular helical slow-wave circuits,were simulated with the software package HFSS10.0 provided by ANSOFT.The simulated results show that the rectangular helical slow-wave structure has higher coupling impedance,smaller size in a traveling wave tube(TWT)than that of a circular one.Moreover,at the given height and helix pitch,when the height/width ratio of the rectangular helical slow-wave structure is greater than 4 i.e.b/a>4,the phase velocity remains unchanged.However,the coupling impedance decreases with an increase of its width.In addition,the phase velocity and the operating voltage can be favorably decreased by reducing the pitch angle.The rectangular helical slow-wave structure has wide applications in printed compact TWT because of its strengths,such as its compatibility to micro electro-mechanical system(MEMS)technology,its capability of coupling with a sheet beam to improve the efficiency.%介绍了用ANSOFT公司提供的HFSS 10.0软件模拟计算色散特性和耦合阻抗的理论方法,并对矩形螺旋线慢波结构的高频特性进行了数值模拟.结果表明:和传统的圆螺旋线结构相比,矩形结构具有更高的耦合阻抗,能有效减小器件体积;在横截面厚度和螺旋角一定的情况下,当矩形螺旋线的宽高比大于4时,相速几乎不变,但是耦合阻抗随着宽度的增加而下降;同时螺旋角的减小可以降低系统的相速,减小工作电压.由于可利用微电子机械系统(MEMS)印制技术制作,具有可与带状电子束作用,提高效率等优点,矩形螺旋线在紧凑型行波管(TWT)领域有广阔的应用前景.

  17. Ostomy Surgery of the Bowel

    Science.gov (United States)

    ... How it Works Digestive Diseases A-Z Ostomy Surgery of the Bowel What is ostomy surgery of the bowel? Ostomy surgery of the bowel, ... It Works . Why does a person need ostomy surgery of the bowel? A person may need ostomy ...

  18. Irritable Bowel Syndrome

    Science.gov (United States)

    ... foods are linked to other digestive conditions like lactose intolerance or celiac disease , though, so it's important to ... MORE ON THIS TOPIC Gastroesophageal Reflux Disease (GERD) Lactose Intolerance Inflammatory Bowel Disease Ulcers Digestive System Eating Well ...

  19. Large bowel resection - discharge

    Science.gov (United States)

    ... large bowel). You may also have had a colostomy . This article describes what to expect after surgery ... have diarrhea. You may have problems with your colostomy. Self-care Follow your health care provider's instructions ...

  20. Small Bowel Prolapse (Enterocele)

    Science.gov (United States)

    ... colorectal function to empty your lower bowel. Kegel exercises Kegel exercises strengthen your pelvic floor muscles, which, ... Accessed July 30, 2014. Hoffman BL, et al. Williams Gynecology. 2nd ed. New York, N.Y.: The ...

  1. Slow Pseudotachylites

    Science.gov (United States)

    Pec, M.; Stunitz, H.; Heilbronner, R.

    2011-12-01

    Tectonic pseudotachylites as solidified, friction induced melts are believed to be the only unequivocal evidence for paleo-earthquakes. Earthquakes occur when fast slip (1 - 3 m/s) propagates on a localized failure plane and are always related with stress drops. The mechanical work expended, together with the rock composition and the efficiency of thermal dissipation, controls whether the temperature increase on a localized slip plane will be sufficient to induce fusion. We report the formation of pseudotachylites during steady-state plastic flow at slow bulk shear strain rates (~10^-3 to ~10^-5 /s corresponding to slip rates of ~10^-6 to ~10^-8 m/s) in experiments performed at high confining pressures (500 MPa) and temperatures (300°C) corresponding to a depth of ~15 km. Crushed granitioid rock (Verzasca gneiss), grain size ≤ 200 μm, with 0.2 wt% water added was placed between alumina forcing blocks pre-cut at 45°, weld-sealed in platinum jackets and deformed with a constant displacement rate in a solid medium deformation apparatus (modified Griggs rig). Microstructural observations show the development of a S-C-C' fabric with C' slip zones being the dominant feature. Strain hardening in the beginning of the experiment is accompanied with compaction which is achieved by closely spaced R1 shears pervasively cutting the whole gouge zone and containing fine-grained material (d 10) are localized in less densely spaced, ~10 μm thick C'-C slip zones which develop predominantly in feldspars and often contain micas. In TEM, they appear to have no porosity consisting of partly amorphous material and small crystalline fragments with the average grain size of 20 nm. After the peak strength, the samples weaken by ~20 MPa and continue deforming up to γ ~ 4 without any stress drops. Strain localization progresses in the C'-C slip zones and leads to the formation of pseudotachylites. Rough estimates of slip rates in the deforming slip zones are 2 to 4 orders of magnitude

  2. Liquid crystal light valves for slow light and applications

    Energy Technology Data Exchange (ETDEWEB)

    Residori, S; Bortolozzo, U [INLN, CNRS, University de Nice Sophia-Antipolis, 1361 route des Lucioles, 06560 Valbonne (France); Huignard, J P, E-mail: jean-pierre.huignard@thalesgroup.co [Thales Research and Technology, RD 128 91767, Palaiseau Cedex (France)

    2010-02-01

    The large dispersive properties of wave mixing in liquid crystal light-valves allow obtaining fast and slow light with tunable group velocities. A slow light interferometer is shown by using this interaction.

  3. Nonlinear Gain Saturation in Active Slow Light Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2013-01-01

    We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated.......We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated....

  4. Bowel vaginoplasty in children

    Directory of Open Access Journals (Sweden)

    Sarin Yogesh

    2006-01-01

    Full Text Available OBJECTIVES: To describe our experience with bowel vaginoplasty done in children. MATERIALS AND METHODS: This is a retrospective study of eight children aged 10 months to 8 years, who underwent bowel vaginoplasty over a period of 5 years (2000-2005. The indications of bowel vaginoplasty included anorectovestibular fistula (ARVF associated with Mayer-Rokitansky-Kuster-Hauser (MRKH syndrome (n=6 and cloaca (n=2. The bowel segment used for vaginoplasty included colon (n=3, ileum (n=2 and duplicated rectum (n=1. In two patients of ARVF associated with uterovaginal agenesis, the distal- most part of ARVF was transected at the level of peritoneal reflection and left as neovagina, whereas the proximal bowel was pulled through at the proposed neo-anal site. All the patients were advised daily home dilatation of the neo vaginal orifice with Hegar′s dilators, for a period of six weeks. RESULTS: Bowel vaginoplasty was done in eight patients. None had any significant per-operative complication. Two patients had abdominal wound dehiscence, requiring secondary suturing. Two patients had mucosal prolapse of the neovagina, which required trimming. One patient died two months after discharge, because of meningitis. Out of the eight patients, seven are in regular follow-up. Six patients have neovagina, cosmetically acceptable to the parents; all have been radiologically proven to have adequate length. One patient had unacceptable perineal appearance with nipple-like vaginal orifice and scarred perineal wound, that merits a revision. None of the patients had vaginal stenosis and excessive mucus discharge, during follow-up visits. Although post surgical results are acceptable to the parents cosmetically, the sexual and psychological outcome is yet to be assessed. Conclusions: Bowel vaginoplasty is a safe and acceptable procedure to treat the pediatric patients of uterovaginal agenesis and cloaca.

  5. Inflammatory bowel disease

    Energy Technology Data Exchange (ETDEWEB)

    Kottler, R.E.; Freson, M. (Groote Schuur Hospital, Cape Town (South Africa). Dept. of Radiology)

    1985-06-01

    Radiology is of considerable value in all forms of inflammatory bowel disease to establish its presence and extent, and to differentiate lesions. The most common inflammatory bowel diseases are Crohn's disease and ulcerative colitis. Crohn's disease may occur anywhere in the disgestive tract, but is most common in the terminal ileum. Since there is no practical endoscopic method of examining the small bowel, barium studies of the latter are most important. Modern radiological techniques, especially the double contrast barium enema, show excellent correlation between the macroscopic changes and the radiological features. Radiology alone does not provide the answers and the radiological features must be interpreted in conjunction with clinical investigation.

  6. FROM SLOW FOOD TO SLOW TOURISM

    Directory of Open Access Journals (Sweden)

    Bac Dorin Paul

    2014-12-01

    Full Text Available One of the effects of globalization is the faster pace of our lives. This rhythm can be noticed in all aspects of life: travel, work, shopping, etc. and it has serious negative effects. It has become common knowledge that stress and speed generate serious medical issues. Food and eating habits in the modern world have taken their toll on our health. However, some people took a stand and argued for a new kind of lifestyle. It all started in the field of gastronomy, where a new movement emerged – Slow Food, based on the ideas and philosophy of Carlo Petrini. Slow Food represents an important adversary to the concept of fast food, and is promoting local products, enjoyable meals and healthy food. The philosophy of the Slow Food movement developed in several directions: Cittaslow, slow travel and tourism, slow religion and slow money etc. The present paper will account the evolution of the concept and its development during the most recent years. We will present how the philosophy of slow food was applied in all the other fields it reached and some critical points of view. Also we will focus on the presence of the slow movement in Romania, although it is in a very early stage of development. The main objectives of the present paper are: to present the chronological and ideological evolution of the slow movement; to establish a clear separation of slow travel and slow tourism, as many mistake on for the other; to review the presence of the slow movement in Romania. Regarding the research methodology, information was gathered from relevant academic papers and books and also from interviews and discussions with local entrepreneurs. The research is mostly theoretical and empirical, as slow food and slow tourism are emerging research themes in academic circles.

  7. 基于二维特异材料波导的表面电磁波的慢波实验研究%Experimental studies of slow wave based on the surface waves in a two-dimensional metamaterials waveguide

    Institute of Scientific and Technical Information of China (English)

    王五松; 张利伟; 张冶文; 方恺

    2013-01-01

    In this paper, we study the slow propagation characteristics of surface electromagnetic waves according to theoretical analysis in the MNG (μ-negative)-DPS (double-positive)-MNG waveguide, which is composed of two-dimensional (2D) metamaterials. The dispersion curves of this waveguide vary with circuit parameter (unit capacitors) of MNG metamaterial. At the cutoff frequency of the dispersion curve the group velocity of electromagnetic wave is equal to zero in theory. So we can obtain slow propagation of the surface waves at different cutoff frequencies just by changing the unit capacitor of the MNG metamaterial. Theoretical analysis also shows that the step changes in slow waves are obtained at some fixed frequencies through changing the unit circuit parameters. The experimental results are in good agreement with simulation results.%本文在理论分析的基础上,实验研究了二维MNG/DPS/MNG(磁单负材料/双正材料/磁单负材料)表面波波导中的慢波效应.该波导的色散曲线随着电路参数(单元电容)的改变而改变,而且在色散曲线的截止频率点,电磁波的群速度理论上等于零.因此可以通过改变MNG区域的电路参数,得到在不同截止频率的慢波特性.另外,本文还通过改变MNG区域的电路参数实现在某一固定频率下波速度渐变的慢波效应.实验结果与仿真结果相一致.

  8. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many t...

  9. [Irritable bowel syndrome].

    Science.gov (United States)

    Kocián, J

    1994-04-01

    Irritable bowel is a functional gastrointestinal disorder with chronic or relapsing symptoms of abdominal pain and impaired frequency and consistency of the faeces caused by obscure structural or biochemical deviations. The frequency of the condition in civilized countries is estimated to amount to 15-20% of the population and it accounts for 25-50% of all patients in gastroenterological ambulatory departments. From the clinical aspect the type with dominant diarrhoea, typically in the morning and very compelling, and the type with pain and constipation are known but even combinations of the two types are encountered. A psychosomatic disorder of the motility of the large bowel and its tonus is involved associated with enhanced pain perception. Despite great efforts to find aetiopathogenetic factors, knowledge still is at the level of obscure theories. The diagnosis is still established per exclusion after all organic causes are ruled out, i.e. we always have to differentiate between an irritable bowel from an irritated one. In therapy the patient's confidence in his doctor is most important and it is essential to gain the patient's active cooperation. In case of diarrhoea a low-residue diet is used, calcium carbonate, codeine, loperamide, conversely in constipation adequate dietary fibre, intake metoclopramide or cisapride. Pain is relieved by spasmolytics or Ca channel blockers in the smooth musculature of the large bowel. The associated dysbiosis is transformed into eubiosis by Lactobacillus or other bacterial products.

  10. Inflammatory bowel disease epidemiology

    DEFF Research Database (Denmark)

    Burisch, Johan; Munkholm, Pia

    2013-01-01

    The occurrence of inflammatory bowel disease (IBD) is increasing worldwide, yet the reasons remain unknown. New therapeutic approaches have been introduced in medical IBD therapy, but their impact on the natural history of IBD remains uncertain. This review will summarize the recent findings in t...... in the epidemiology of IBD....

  11. Small Bowel Lymphangioma

    Directory of Open Access Journals (Sweden)

    Shou-jiang Tang

    2014-01-01

    Conclusions: Small bowel lymphangiomas can cause gross or occult GI bleeding, anemia, abdominal pain, and/or obstruction. Endoscopists should be aware of this rare tumor and its unique endoscopic features. The optimal treatment is radical excision, since incomplete resection may lead to recurrence. Argon plasma coagulation or polypectomy have been used to achieve endoscopic ablation and palliation of GI bleeding.

  12. Small bowel obstruction- a surprise.

    Science.gov (United States)

    Mathew, Jeffrey Daniel; Cp, Ganesh Babu; M, Balachandar; M, Ramanathan

    2015-01-01

    Trans - omental hernia is very rare, accounting to 1-4% of all internal hernias which is an unusual cause of small bowel obstruction. Here we present a case report of a small bowel obstruction in a female due to trans - omental hernia presenting with central abdominal pain, distension and bilious vomiting. She had no previous history of trauma, surgery. Plain X-ray abdomen erect showed multiple air fluid levels with dilated small bowel loops. Emergency laparotomy revealed a segment of congested small bowel loop (ileum) through a defect in greater omentum. On table the herniated bowel loop was reduced and the defect in greater omentum was closed primarily. There was no necessity for bowel resection as it regained normal colour after reduction. Postoperative period was uneventful with complete resolution of symptoms. This case is presented for its rarity and its importance in clinical differential diagnosis of acute abdomen due to small bowel obstruction.

  13. Growth of Pollen Tubes of Papaver rhoeas Is Regulated by a Slow-Moving Calcium Wave Propagated by Inositol 1,4,5-Trisphosphate.

    Science.gov (United States)

    Franklin-Tong, V. E.; Drobak, B. K.; Allan, A. C.; Watkins, PAC.; Trewavas, A. J.

    1996-08-01

    A signaling role for cytosolic free Ca2+ ([Ca2+]i) in regulating Papaver rhoeas pollen tube growth during the self-incompatibility response has been demonstrated previously. In this article, we investigate the involvement of the phosphoinositide signal transduction pathway in Ca2+-mediated pollen tube inhibition. We demonstrate that P. rhoeas pollen tubes have a Ca2+-dependent polyphosphoinositide-specific phospholipase C activity that is inhibited by neomycin. [Ca2+]i imaging after photolysis of caged inositol (1,4,5)-trisphosphate (Ins[1,4,5]P3) in pollen tubes demonstrated that Ins(1,4,5)P3 could induce Ca2+ release, which was inhibited by heparin and neomycin. Mastoparan, which stimulated Ins(1,4,5)P3 production, also induced a rapid increase in Ca2+, which was inhibited by neomycin. These data provide direct evidence for the involvement of a functional phosphoinositide signal-transducing system in the regulation of pollen tube growth. We suggest that the observed Ca2+ increases are mediated, at least in part, by Ins(1,4,5)P3-induced Ca2+ release. Furthermore, we provide data suggesting that Ca2+ waves, which have not previously been reported in plant cells, can be induced in pollen tubes.

  14. Irritable bowel syndrome, inflammatory bowel disease and the microbiome

    OpenAIRE

    2014-01-01

    Purpose of review The review aims to update the reader on current developments in our understanding of how the gut microbiota impact on inflammatory bowel disease and the irritable bowel syndrome. It will also consider current efforts to modulate the microbiota for therapeutic effect. Recent findings Gene polymorphisms associated with inflammatory bowel disease increasingly suggest that interaction with the microbiota drives pathogenesis. This may be through modulation of the immune response,...

  15. Small Bowel Hamartoma: A Huge Diverticulum of Small Bowel

    Directory of Open Access Journals (Sweden)

    Hamdi Ebdewi

    2013-01-01

    Full Text Available A-20-year old male, with no significant medical history, presented with clinical features mimicking a perforated acute appendicitis. Because of features of peritonitis, a laparotomy was performed which showed a segment of small bowel with multiple large diverticula and mesenteric cysts. A segmental small bowel resection was performed. The patient made an uneventful recovery from surgery. Histology revealed features of a small bowel hamartoma.

  16. Short bowel syndrome.

    LENUS (Irish Health Repository)

    Donohoe, Claire L

    2012-02-01

    The short bowel syndrome (SBS) is a state of malabsorption following intestinal resection where there is less than 200 cm of intestinal length. The management of short bowel syndrome can be challenging and is best managed by a specialised multidisciplinary team. A good understanding of the pathophysiological consequences of resection of different portions of the small intestine is necessary to anticipate and prevent, where possible, consequences of SBS. Nutrient absorption and fluid and electrolyte management in the initial stages are critical to stabilisation of the patient and to facilitate the process of adaptation. Pharmacological adjuncts to promote adaptation are in the early stages of development. Primary restoration of bowel continuity, if possible, is the principle mode of surgical treatment. Surgical procedures to increase the surface area of the small intestine or improve its function may be of benefit in experienced hands, particularly in the paediatric population. Intestinal transplant is indicated at present for patients who have failed to tolerate long-term parenteral nutrition but with increasing experience, there may be a potentially expanded role for its use in the future.

  17. Small bowel imaging of inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Emanuele; Casciani; Chiara; De; Vincentiis; Gianfranco; Gualdi

    2015-01-01

    The study of the small bowel(SB) has always beenchallenging both for clinicians and radiologist. It is a long and tortuous tube that can be affected by various pathologies whose signs and symptoms are usually non specific and can mimic other acute abdominal disorders. For these reasons, imaging plays a central role in the diagnosis of the different pathological conditions that can occur. They are important also in the management and follow up of chronic diseases. We expose and evaluate all the radiological methods that are now available for the study of the SB with particular emphasis on the technological improvement of cross-sectional imaging, such as computed tomography(CT) and magnetic resonance imaging(MRI). These techniques have, infact, highly improved in terms of execution times(fast acquisitions images), patients discomfort and radiation dose, for CT, with consequent reduced biological risks. Moreover, the new post-processing options with multiplanar reconstruction and isotropic images have made significant changes in the evaluation of the exams. Especially MRI scans have been improved by the advent of new sequences, such as diffusion weighted imaging and cine-MRI, parallel imaging and breath-hold sequences and can provide excellent soft-tissue contrast without the use of ionizing radiations.

  18. Optimal Bowel Preparation for Video Capsule Endoscopy

    Directory of Open Access Journals (Sweden)

    Hyun Joo Song

    2016-01-01

    Full Text Available During video capsule endoscopy (VCE, several factors, such as air bubbles, food material in the small bowel, and delayed gastric and small bowel transit time, influence diagnostic yield, small bowel visualization quality, and cecal completion rate. Therefore, bowel preparation before VCE is as essential as bowel preparation before colonoscopy. To date, there have been many comparative studies, consensus, and guidelines regarding different kinds of bowel cleansing agents in bowel preparation for small bowel VCE. Presently, polyethylene glycol- (PEG- based regimens are given primary recommendation. Sodium picosulphate-based regimens are secondarily recommended, as their cleansing efficacy is less than that of PEG-based regimens. Sodium phosphate as well as complementary simethicone and prokinetics use are considered. In this paper, we reviewed previous studies regarding bowel preparation for small bowel VCE and suggested optimal bowel preparation of VCE.

  19. Stones from bowel disease.

    Science.gov (United States)

    Worcester, Elaine M

    2002-12-01

    Kidney stones are increased in patients with bowel disease, particularly those who have had resection of part of their gastrointestinal tract. These stones are usually CaOx, but there is a marked increase in the tendency to form uric acid stones, as well, particularly in patients with colon resection. These patients all share a tendency to chronic volume contraction due to loss of water and salt in diarrheal stool, which leads to decreased urine volumes. They also have decreased absorption, and therefore diminished urinary excretion, of citrate and magnesium, which normally act as inhibitors of CaOx crystallization. Patients with colon resection and ileostomy form uric acid stones, as loss of bicarbonate in the ileostomy effluent leads to formation of an acid urine. This, coupled with low urine volume, decreases the solubility of uric acid, causing crystallization and stone formation. Prevention of stones requires treatment with alkalinizing agents to raise urine pH to about 6.5, and attempts to increase urine volume, which increases the solubility of uric acid and prevents crystallization. Patients with small bowel resection may develop steatorrhea; if the colon is present, they are at risk of hyperoxaluria due to increased permeability of the colon to oxalate in the presence of fatty acids, and increased concentrations of free oxalate in the bowel lumen due to fatty acid binding of luminal calcium. EH leads to supersaturation of urine with respect to CaOx, in conjunction with low volume, hypocitraturia and hypomagnesuria. Therapy involves a low-fat, low-oxalate diet, attempts to increase urine volume, and agents such as calcium given to bind oxalate in the gut lumen. Correction of hypocitraturia and hypomagnesuria are also helpful.

  20. Inflammatory bowel disease unclassified

    Institute of Scientific and Technical Information of China (English)

    Ning ZHOU; Wei-xing CHEN; Shao-hua CHEN; Cheng-fu XU; You-ming LI

    2011-01-01

    Objective: Inflammatory bowel diseases (IBDs) are idiopathic, chronic, and inflammatory intestinal disorders. The two main types, ulcerative colitis (UC) and Crohn's disease (CD), sometimes mimic each other and are not readily distinguishable. The purpose of this study was to present a series of hospitalized cases, which could not initially be classified as a subtype of IBD, and to try to note roles of the terms indeterminate colitis (IC) and inflammatory bowel disease unclassified (IBDU) when such a dilemma arises. Methods: Medical records of 477 patients hospitalized due to IBD, during the period of January 2002 to April 2009, were retrospectively studied in the present paper. All available previous biopsies from endoscopies of these patients were reanalyzed. Results: Twenty-seven of 477 IBD patients (5.7%) had been initially diagnosed as having IBDU. Of them, 23 received colonoscopy and histological examinations in our hospital. A total of 90% (9/10) and 66.7% (4/6) of patients, respectively, had a positive finding via wireless capsule endoscopy (CE) and double-balloon enteroscopy (DBE). The barium-swallow or small bowel follow-through (SBFT) was performed on 11 patients. Positive changes were observed under computer tomographic (CT) scanning in 89.5% (17/19) of patients. Reasonable treatment strategies were employed for all patients. Conclusions: Our data indicate that IBDU accounts for 5.7% of initial diagnoses of IBD. The definition of IBDU is valuable in clinical practice. For those who had no clear clinical, endoscopic, histological, or other features affording a diagnosis of either UC or CD,IBDU could be used parenthetically.

  1. [Diagnosis of functional bowel diseases].

    Science.gov (United States)

    Kruis, W

    2007-02-28

    Functional bowel disorders cause frequent doctor visits. The term comprises various disease entities. Most frequent are the irritable bowel syndrome, functional constipation and functional diarrhea. An exact history plays an outstanding role for the diagnosis of all these entities. History either confirms a positive diagnosis or initiates some complementary investigations. Redundant and dangerous technical procedures should be avoided in the diagnostic work up.

  2. Small Bowel Review - Part I

    OpenAIRE

    ABR Thomson; Wild, G.

    1997-01-01

    Significant advances have been made in the study of the small bowel. Part I of this two-part review of the small bowel examines carbohydrates, including brush border membrane hydrolysis and sugar transport; amino acids, dipeptides, proteins and food allergy, with a focus on glutamine, peptides and macromolecules, and nucleoside...

  3. Leven met Inflammatory Bowel Disease

    NARCIS (Netherlands)

    Duijvendijk J. van, [No Value

    2004-01-01

    Leven met Inflammatory Bowel Disease Inflammatory bowel disease (IBD) is de verzamelnaam voor Colitis ulcerosa en de ziekte van Crohn. Het zijn chronische darmontstekingen, waarvan de ziekteactiviteit wisselt en zich niet laat voorspellen. Door de lichamelijke klachten en het onvoorspelbare karakter

  4. Small bowel transplantation: An overview

    NARCIS (Netherlands)

    R.W.F. de Bruin (Ron); E. Heineman (Erik); R.L. Marquet (Richard)

    1994-01-01

    textabstractSmall bowel transplantation (SBT) would, in theory, be the treatment of choice for patients suffering from the short bowel syndrome. Although SBT has been done with a considerable degree of success in some centers [36,145], it is by no means an established or widely applicable therapy fo

  5. Inflammatory bowel disease.

    Science.gov (United States)

    Walsh, Anne; Mabee, John; Trivedi, Kashyap

    2011-09-01

    Crohn disease and ulcerative colitis are the most common forms of inflammatory bowel disease (IBD) likely to be encountered in primary care. Patient-centered care is essential for positive outcomes, and should include long-term continuity with an empathetic primary care provider who can provide skillful coordination of the requisite multidisciplinary approach. Early suspicion of the diagnosis and referral to expert gastroenterologists for confirmation and medical management is essential. Coordinating interdisciplinary consultations, including colorectal surgeons, radiologists, stoma therapists, psychologists, and rheumatologists, in combination with comprehensive patient education, is key to decreasing overall morbidity, mortality, and health care costs associated with IBD.

  6. Kirsner's inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    R Balfour Sarto; William J Sandborn

    2005-01-01

    @@ Very few medical textbooks have so thoroughly dominated,and even defined a field, as has Inflammatory Bowel Diseases by Joe Kirsner. Originally co-edited with Roy Shorter of Mayo Clinic, this book, beginning with its first edition in 1975, encapsulated the science and art of caring for patients with Crohn's disease and ulcerative colitis. Thus it is with considerable respect, and indeed some awe and trepidation,that we eagerly embraced the opportunity to assume the editorship of this preeminent textbook and the obligation to transition it to reflect the changing, increasingly complex pathophysiology and treatment of these diseases.

  7. INFLAMMATORY BOWEL DISEASE

    Directory of Open Access Journals (Sweden)

    I Gusti Ayu Mahaprani Danastri

    2013-02-01

    Full Text Available Crohn disease (CD and ulcerative colitis (UC is an chronic inflammation in the gastrointestinal tract. Colecctively, they are called inflammatory bowel disease (IBD, and about 1,5 millions people in America suffering from UC and CD. The cause of UC and CD is unknown, but the expert believe that UC and CD are caused by a disturbed immune response in someone who has a genetic predisposition. UC and CD have a significant recurrency  and remission rate. Surgery in UC is a curative treatment for colon’s disease and a potentially colon’s malignancy, but it is not a curative treatment for CD.

  8. 昆仑山强震前的震颤波并非源自慢地震%The tremor wave before the Kunlun strong earthquake is not slow earthquake event

    Institute of Scientific and Technical Information of China (English)

    张雁滨; 蒋骏; 李才媛; 唐焱; 朱健; 徐锐

    2013-01-01

    A few days before the western Kunlun mountain pass earthquake of MS8. 1 on November 14, 2001, a number of Chinese seismic stations observed low-frequency anomalous tremor wave signals which lasted several days. Because these tremor waves have been observed before the earthquake, so they got full attention. For many years, many researchers discussed the cause of the tremor waves, but the question is still not settled yet. Is the tremor wave from a slow earthquake event in the Kunlun mountain pass earthquake region? Is it the earthquake precursor or due to other factors? To answer these questions, we make use of the continuous data recorded by broadband seismometers in 10 stations in China seismic network before the Kunlun mountain pass earthquake, to analyze and research the tremor wave signal in characteristics, the duration, the tremor wave magnitude changes and large-scale atmospheric motion, the relationship between the signal amplitude with observation of the space change characteristics attenuation in this article. The results show that the tremor wave signal before the Kunlun mountain pass earthquake in November of 2001 consists of two components. One began to appear on November 10, lasted from November 10—13, with the main frequency of 0. 15 ~0. 22 Hz (period of 4~7 s), and was caused by the western Pacific typhoon Ling Ling. The other one began to appear November 11, lasted from November 11—12, with main frequency of 0. l~0. 13 Hz (period of 7 — 10 s), was neither a slow earthquake event from the Kunlun mountain pass earthquake area, but caused by strong extratropical cyclone movement in Eurasia.%2001年11月14日的昆仑山Ms8.1级地震前几天,中国地震台网多个台站都观测到了持续数天的低频震颤波信号.由于这些震颤波发生在强震前,所以备受关注.多年来研究人员对该震颤波的产生原因进行过多方探讨,但没有定论.该震颤波信号是否源自强震区的慢地震?是否是地震前兆?或

  9. Impact of the electron beam tunnel on a folded waveguide slow-wave structure%电子注通道形貌对折叠波导慢波结构的影响

    Institute of Scientific and Technical Information of China (English)

    王亚军; 陈樟; 施志贵

    2013-01-01

    The folded waveguide structure is a promising slow-wave structure for terahertz traveling wave tubes.The influence of the beam tunnel on the circuit cold characteristics was analyzed,including dispersion relation,interaction impedance and circuit attenuation.The simulation results show that a beam tunnel with a rectangular cross section exhibits slightly steeper dispersion relation and higher attenuation coefficient than the beam tunnel with a circular cross section.Compared with the beam tunnel with a circular cross section,interaction impedance of beam tunnel with a rectangular cross section is lower about 0.5 Ω at a 220 GHz central frequency.For cold beam,the linear theory predicts a gain growth rate of 4.85 dB/cm and 5.22 dB/cm,respectively.They have a similar 3dB bandwidth of 6.3 GHz and 7.2 GHz.The large signal simulations show that the nonlinear gain is 24.42 dB and 28.44 dB at 220 GHz for 54 mm (100 periods)folded waveguide slow-wave structure with rectangular cross section and circular cross section,respectively.%折叠波导结构是一种极具潜力的太赫兹行波管慢波电路.分析了电子注通道形貌对折叠波导高频特性的影响,包括色散特性、耦合阻抗和衰减特性.仿真结果表明,相比于圆形电子注通道,矩形电子注通道的折叠波导结构色散要略微陡一些,损耗也要略微高一些.在中心频率处,矩形电子注通道结构的耦合阻抗比圆形电子注通道结构低0.5Ω左右.皮尔斯小信号理论表明,在中心频率处,矩形电子注通道结构和圆形电子注通道结构的增益速率分别为4.85 dB/cm和5.22 dB/cm,具有相似的3 dB带宽,约为6.3 GHz和7.2 GHz.粒子模拟表明,对于矩形和圆形电子注通道,54 mm(100个周期)的折叠波导慢波结构在220 GHz增益分别为24.42 dB和28.44 dB.

  10. Count Bowell at record heliocentric distance

    Science.gov (United States)

    Meech, Karen J.; Jewitt, David

    1987-01-01

    New observations of Comet Bowell at the record distance of 13.6 AU are presented. An extended coma is present, the size of which is consistent with the same slow expansion rate of roughly 1 m/s detected around perihelion. The cross-section of the solid grains within the central 10 arcsec of the coma has decreased by over an order of magnitude since 1980-84, which indicates that the coma production is declining. The decline began near R of roughly 10 AU, the same distance at which production began on the preperihelion leg. The coma at R of 10 AU or less may be formed by sublimation of CO2 or an ice of similar volatility from the nucleus.

  11. Too slow, for Milton

    OpenAIRE

    Armstrong, N.

    2011-01-01

    Too slow, for Milton was written in 2011, as part of a memorial project for Milton Babbitt. The piece borrows harmonies from Babbitt's Composition for 12 Instruments (harmonies which Babbitt had in turn borrowed from Schoenberg's Ode to Napoleon), but unfolds them as part of a musical texture characterised by repetition, resonance, and a slow rate of change. As Babbitt once told me that my music was 'too slow', this seemed an appropriately obstinate form of homage.

  12. Does stress induce bowel dysfunction?

    Science.gov (United States)

    Chang, Yu-Ming; El-Zaatari, Mohamad; Kao, John Y

    2014-08-01

    Psychological stress is known to induce somatic symptoms. Classically, many gut physiological responses to stress are mediated by the hypothalamus-pituitary-adrenal axis. There is, however, a growing body of evidence of stress-induced corticotrophin-releasing factor (CRF) release causing bowel dysfunction through multiple pathways, either through the HPA axis, the autonomic nervous systems, or directly on the bowel itself. In addition, recent findings of CRF influencing the composition of gut microbiota lend support for the use of probiotics, antibiotics, and other microbiota-altering agents as potential therapeutic measures in stress-induced bowel dysfunction.

  13. Small Bowel Review - Part I

    OpenAIRE

    Thomson, ABR; Wild, G.

    1997-01-01

    Significant advances have been made in the study of the small bowel. Part I of this two-part review of the small bowel examines carbohydrates, including brush border membrane hydrolysis and sugar transport; amino acids, dipeptides, proteins and food allergy, with a focus on glutamine, peptides and macromolecules, and nucleosides, nucleotides and polyamines; salt and water absorption, and diarrhea, including antidiarrheal therapy and oral rehydration treatment; lipids (digestion and absorption...

  14. Slow light in tapered slot photonic crystal waveguide

    Institute of Scientific and Technical Information of China (English)

    WU Jun; LI YanPing; YANG ChuanChuan; PENG Chao; WANG ZiYu

    2009-01-01

    A slotted single-mode photonic crystal waveguide with a linear tapered slot is presented to realize slow light, whose dispersion curve is shifted by changing the slot width. When the slot width is reduced, the band curve shifts in the tapered structure, and the group velocity of light approach zero at the cut-off frequency. Therefore, different frequency components of the guided light are slowed down even loca-lized along the propagation direction inside a tapered slot photonic crystal waveguide. Furthermore, this structure can confine slow light-wave in a narrow slot waveguide, which may effectively enhance the interaction between slow light and the low-index wave-guiding materials filled in the slot. In addition, this tapered slot structure can be used to compensate group velocity dispersion of slow light by mod-ifying the structure, thus opening the opportunity for ultra-wide bandwidth slow light.

  15. Small bowel faeces sign in patients without small bowel obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, S.L. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States)]. E-mail: stacylynnjacobs@yahoo.com; Rozenblit, A. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States); Ricci, Z. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States); Roberts, J. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States); Milikow, D. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States); Chernyak, V. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States); Wolf, E. [Department of Radiology, Montefiore Medical Center, Bronx, NY (United States)

    2007-04-15

    Aim: To evaluate frequency and clinical relevance of the 'small bowel faeces' sign (SBFS) on computed tomography (CT) in patients with and without small bowel obstruction (SBO) presenting with acute abdominal or acute abdominal and flank pain. Methods: Abdominal CTs of consecutive patients presenting to the emergency department with abdominal or flank pain over a 6 month period were retrospectively reviewed by six radiologists, independently, for the presence of the SBFS. Examinations with positive SBFS were further evaluated in consensus by three radiologists, blinded to the final diagnosis. The small bowel was graded as non-dilated (<2.5 cm) and mildly (2.5-2.9 cm), moderately (3-4 cm) or severely (>4 cm) dilated. The location of SBFS and presence of distal small bowel collapse indicative of SBO was recorded. Imaging findings were subsequently correlated with the final diagnosis via chart review and compared between patients with and without SBO. Results: Of 1642 CT examinations, a positive SBFS was found in 100 (6%) studies. Of 100 patients with a positive SBFS, 32 (32%) had documented SBO. The remaining 68 patients had other non-obstructive diagnoses. SBFS was located in proximal, central, distal and multisegmental bowel loops in one (3.1%), eight (25.0%), 21 (65.6%) and two (6.3%) patients with SBO, and in zero (0%), 10 (14.7%), 53 (77.9%) and five (7.4%) of patients without SBO (p < 0.273). The small bowel was non-dilated and mildly, moderately or severely dilated in one (3%), five (16%), 20 (62%) and six (19%) patients with SBO, and in 61(90%), seven (10%), zero (0%) and zero (0%) patients without SBO. Normal or mildly dilated small bowel was seen in all (100%) patients without SBO, but only in six (19%) of 32 patients with SBO (p < 0.0001). Moderate or severe small bowel dilatation was seen in 26 (81%) patients with SBO (p < 0.0001), but it was absent in patients without SBO. Distal small bowel collapse was found in 27 (84.4%) of 32 patients with

  16. Outcomes of bowel program in spinal cord injury patients with neurogenic bowel dysfunction

    Institute of Scientific and Technical Information of China (English)

    Zuhal Ozisler; Kurtulus Koklu; Sumru Ozel; Sibel Unsal-Delialioglu

    2015-01-01

    In this study, we aimed to determine gastrointestinal problems associated with neurogenic bowel dysfunction in spinal cord injury patients and to assess the efifcacy of bowel program on gas-trointestinal problems and the severity of neurogenic bowel dysfunction. Fifty-ifve spinal cord injury patients were included in this study. A bowel program according to the characteristics of neurogenic bowel dysfunction was performed for each patient. Before and after bowel program, gastrointestinal problems (constipation, dififcult intestinal evacuation, incontinence, abdominal pain, abdominal distension, loss of appetite, hemorrhoids, rectal bleeding and gastrointestinal induced autonomic dysrelfexia) and bowel evacuation methods (digital stimulation, oral med-ication, suppositories, abdominal massage, Valsalva maneuver and manual evacuation) were determined. Neurogenic bowel dysfunction score was used to assess the severity of neurogenic bowel dysfunction. At least one gastrointestinal problem was identiifed in 44 (80%) of the 55 patients before bowel program. Constipation (56%, 31/55) and incontinence (42%, 23/55) were the most common gastrointestinal problems. Digital rectal stimulation was the most common method for bowel evacuation, both before (76%, 42/55) and after (73%, 40/55) bowel program. Oral medication, enema and manual evacuation application rates were signiifcantly decreased and constipation, dififcult intestinal evacuation, abdominal distention, and abdominal pain rates were signiifcantly reduced after bowel program. In addition, mean neurogenic bowel dysfunction score was decreased after bowel program. An effective bowel program decreases the severity of neurogenic bowel dysfunction and reduces associated gastrointestinal problems in patients with spinal cord injury.

  17. Outcomes of bowel program in spinal cord injury patients with neurogenic bowel dysfunction

    Directory of Open Access Journals (Sweden)

    Zuhal Ozisler

    2015-01-01

    Full Text Available In this study, we aimed to determine gastrointestinal problems associated with neurogenic bowel dysfunction in spinal cord injury patients and to assess the efficacy of bowel program on gastrointestinal problems and the severity of neurogenic bowel dysfunction. Fifty-five spinal cord injury patients were included in this study. A bowel program according to the characteristics of neurogenic bowel dysfunction was performed for each patient. Before and after bowel program, gastrointestinal problems (constipation, difficult intestinal evacuation, incontinence, abdominal pain, abdominal distension, loss of appetite, hemorrhoids, rectal bleeding and gastrointestinal induced autonomic dysreflexia and bowel evacuation methods (digital stimulation, oral medication, suppositories, abdominal massage, Valsalva maneuver and manual evacuation were determined. Neurogenic bowel dysfunction score was used to assess the severity of neurogenic bowel dysfunction. At least one gastrointestinal problem was identified in 44 (80% of the 55 patients before bowel program. Constipation (56%, 31/55 and incontinence (42%, 23/55 were the most common gastrointestinal problems. Digital rectal stimulation was the most common method for bowel evacuation, both before (76%, 42/55 and after (73%, 40/55 bowel program. Oral medication, enema and manual evacuation application rates were significantly decreased and constipation, difficult intestinal evacuation, abdominal distention, and abdominal pain rates were significantly reduced after bowel program. In addition, mean neurogenic bowel dysfunction score was decreased after bowel program. An effective bowel program decreases the severity of neurogenic bowel dysfunction and reduces associated gastrointestinal problems in patients with spinal cord injury.

  18. 金属柱平板慢波系统高频特性研究%Study of high frequency characteristics of metallic-pole-planar slow wave structure

    Institute of Scientific and Technical Information of China (English)

    史宗君; 杨梓强; 侯钧; 兰峰; 梁正

    2011-01-01

    对于离散的金属柱结构构建的周期性平板慢波系统,本文利用3维FDTD方法结合HFSS仿真软件深入分析了该慢波系统的高频特性.研究了金属柱高度、周期长度对色散特性的影响,计算了耦合阻抗,并与传统光栅慢波系统特性进行了对比分析.分析表明金属柱慢波系统既有与传统光栅慢波系统相似的高频特性,又具有独自的特点,位于离散的金属柱周期间隙中的电子注互作用耦合阻抗具有对称性;金属柱结构用作真空电子器件的高频系统可增加发生有效互作用的电子注厚度,降低起振电流密度,提高器件效率.本文的分析结果为设计低电流密度工作的多电子注短毫米波器件提供了依据.%The discrete metallic-pole-planar slow wave structure (SWS) is introduced in this paper, and the high frequency characteristics are studied. And procedures based on three-dimensional finite-difference time-domain (3-D FDTD ) arithmetic are used to calculate the dispersive characteristics of the new SWS, and HFSS simulation software is used to analyze the coupling impedance. Results show the high frequency characteristics of the pole structure not only have a general similarity in comparison with these of the grating, but also have itself advantages. For the electrons moving between multiple poles of the structure, the interaction impedances are symmetry; relatively thick electron beams can efficiently interact with the high-frequency field while it used as the high frequency system of vacuum electronic devices.This kind of SWS is promising to lower the starting current density and have better efficiency than the traditional grating SWS. According to the results, a sub-millimeter radiation source driven by the multiple beams can be designed at a low operating current density.

  19. Inflammatory bowel disease: pathogenesis.

    Science.gov (United States)

    Zhang, Yi-Zhen; Li, Yong-Yu

    2014-01-07

    Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is characterized by chronic relapsing intestinal inflammation. It has been a worldwide health-care problem with a continually increasing incidence. It is thought that IBD results from an aberrant and continuing immune response to the microbes in the gut, catalyzed by the genetic susceptibility of the individual. Although the etiology of IBD remains largely unknown, it involves a complex interaction between the genetic, environmental or microbial factors and the immune responses. Of the four components of IBD pathogenesis, most rapid progress has been made in the genetic study of gut inflammation. The latest internationally collaborative studies have ascertained 163 susceptibility gene loci for IBD. The genes implicated in childhood-onset and adult-onset IBD overlap, suggesting similar genetic predispositions. However, the fact that genetic factors account for only a portion of overall disease variance indicates that microbial and environmental factors may interact with genetic elements in the pathogenesis of IBD. Meanwhile, the adaptive immune response has been classically considered to play a major role in the pathogenesis of IBD, as new studies in immunology and genetics have clarified that the innate immune response maintains the same importance in inducing gut inflammation. Recent progress in understanding IBD pathogenesis sheds lights on relevant disease mechanisms, including the innate and adaptive immunity, and the interactions between genetic factors and microbial and environmental cues. In this review, we provide an update on the major advances that have occurred in above areas.

  20. Highly Alfvenic Slow Solar Wind

    Science.gov (United States)

    Roberts, D. Aaron

    2010-01-01

    It is commonly thought that fast solar wind tends to be highly Alfvenic, with strong correlations between velocity and magnetic fluctuations, but examples have been known for over 20 years in which slow wind is both Alfvenic and has many other properties more typically expected of fast solar wind. This paper will present a search for examples of such flows from more recent data, and will begin to characterize the general characteristics of them. A very preliminary search suggests that such intervals are more common in the rising phase of the solar cycle. These intervals are important for providing constraints on models of solar wind acceleration, and in particular the role waves might or might not play in that process.

  1. Tumours in the Small Bowel

    Directory of Open Access Journals (Sweden)

    N. Kurniawan

    2014-01-01

    Full Text Available Small bowel tumours are rare and originate from a wide variety of benign and malignant entities. Adenocarcinomas are the most frequent primary malignant small bowel tumours. Submucosal tumours like gastrointestinal stromal tumours (GIST or neuroendocrine tumours (NET may show a central umbilication, pathologic vessels, bridging folds or an ulceration of the overlying mucosa. These signs help to differentiate them from harmless bulges caused by impression from outside, e.g. from other intestinal loops. Sarcomas of the small bowel are rare neoplasias with mesenchymal origin, sometimes presenting as protruding masses. Benign tumours like lipoma, fibrolipoma, fibroma, myoma, and heterotopias typically present as submucosal masses. They cannot be differentiated endoscopically from those with malignant potential as GIST or NET. Neuroendocrine carcinomas may present with diffuse infiltration, which may resemble other malignant tumours. The endoscopic appearance of small bowel lymphomas has a great variation from mass lesions to diffuse infiltrative changes. Melanoma metastases are the most frequent metastases to the small bowel. They may be hard to distinguish from other tumours when originating from an amelanotic melanoma.

  2. Intestinal adaptation in short bowel syndrome

    NARCIS (Netherlands)

    Welters, C.F.M.; Dejong, C.H.C.; Deutz, N.E.P.; Heineman, E.

    2002-01-01

    Intestinal adaptation in short bowel syndrome. Welters CF, Dejong CH, Deutz NE, Heineman E. Department of Surgery, Academic Hospital and University of Maastricht, The Netherlands. Regaining enteral autonomy after extensive small bowel resection is dependent on intestinal adaptation. This adaptationa

  3. Slow light beam splitter.

    Science.gov (United States)

    Xiao, Yanhong; Klein, Mason; Hohensee, Michael; Jiang, Liang; Phillips, David F; Lukin, Mikhail D; Walsworth, Ronald L

    2008-07-25

    We demonstrate a slow light beam splitter using rapid coherence transport in a wall-coated atomic vapor cell. We show that particles undergoing random and undirected classical motion can mediate coherent interactions between two or more optical modes. Coherence, written into atoms via electromagnetically induced transparency using an input optical signal at one transverse position, spreads out via ballistic atomic motion, is preserved by an antirelaxation wall coating, and is then retrieved in outgoing slow light signals in both the input channel and a spatially-separated second channel. The splitting ratio between the two output channels can be tuned by adjusting the laser power. The slow light beam splitter may improve quantum repeater performance and be useful as an all-optical dynamically reconfigurable router.

  4. Small Bowel Review - Part I

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    1997-01-01

    Full Text Available Significant advances have been made in the study of the small bowel. Part I of this two-part review of the small bowel examines carbohydrates, including brush border membrane hydrolysis and sugar transport; amino acids, dipeptides, proteins and food allergy, with a focus on glutamine, peptides and macromolecules, and nucleosides, nucleotides and polyamines; salt and water absorption, and diarrhea, including antidiarrheal therapy and oral rehydration treatment; lipids (digestion and absorption, fatty acid binding proteins, intracellular metabolism, lipoproteins and bile acids; and metals (eg, iron and vitamins.

  5. Slowing Kidney Disease

    Science.gov (United States)

    ... takes years of daily use for NSAIDs to cause CKD. But, once CKD is present, NSAIDs can make ... in the wrong places can “oxidize” and cause damage, a lot like rust. Antioxidants ... Fish oil can help slow CKD that is caused by a disease called IgA ...

  6. Nonlinear dynamical triggering of slow slip

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Knuth, Matthew W [WISCONSIN; Kaproth, Bryan M [PENN STATE; Carpenter, Brett [PENN STATE; Guyer, Robert A [Los Alamos National Laboratory; Le Bas, Pierre - Yves [Los Alamos National Laboratory; Daub, Eric G [Los Alamos National Laboratory; Marone, Chris [PENN STATE

    2010-12-10

    Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads ({approx}1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred

  7. A multidisciplinary approach to short bowel syndrome.

    Science.gov (United States)

    Denegri, Andrea; Paparo, Francesco; Denegri, Roberto; Revelli, Matteo; Frascio, Marco; Rollandi, Gian Andrea; Fornaro, Rosario

    2014-01-01

    Short bowel syndrome is a complex clinical picture, characterized by signs and symptoms of malabsorption and subsequent malnutrition, which often occurs after extensive bowel resections. Short bowel syndrome's treatment must begin together with the planning of the first surgery, especially for disease that may need multiple interventions. Patients with short bowel should be individually managed because they all are different in diagnosis, length of the remaining bowel and in psychosocial characteristics. For all these reasons, a multidisciplinary approach between the various specialists is therefore needed.

  8. Exitation of Whistler Waves by a Helical Wave Structure

    DEFF Research Database (Denmark)

    Balmashnov, A. A.; Lynov, Jens-Peter; Michelsen, Poul;

    1981-01-01

    The excitation of whistler waves in a radial inhomogeneous plasma is investigated experimentally, using a slow-wave structure consisting of a helix of variable length surrounding the plasma column. The excited waves were observed to have a wave-vector parallel to the external magnetic field...

  9. Short Bowel Syndrome: clinical management

    OpenAIRE

    Loris Pironi; Mariacristina Guidetti; Elisabetta Lanzoni; Caterina Pazzeschi; Catia Corsini

    2008-01-01

    The management of a case of intestinal failure due to Short Bowel Syndrome (SBS) is described. Patients’ care needs an expert multidisciplinary approach. Published data have demonstrated that the lack of a specialist staff is a risk factor for patients’ death. The creation of networks linking non-specialist doctors with dedicated centers is recommended.

  10. Cancer in inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Jianlin Xie; Steven H Itzkowitz

    2008-01-01

    Patients with long-standing inflammatory bowel disease (IBD) have an increased risk of developing colorectal cancer (CRC). Many of the molecular alterations responsible for sporadic colorectal cancer, namely chromosomal instability, microsatellite instability, and hypermethylation, also play a role in colitis-associated colon carcinogenesis. Colon cancer risk in inflammatory bowel disease increases with longer duration of colitis, greater anatomic extent of colitis, the presence of primary sclerosing cholangitis, family history of CRC and degree of inflammation of the bowel. Chemoprevention includes aminosalicylates, ursodeoxycholic acid, and possibly folic acid and statins. To reduce CRC mortality in IBD, colonoscopic surveillance with random biopsies remains the major way to detect early mucosal dysplasia. When dysplasia is confirmed, proctocolectomy is considered for these patients. Patients with small intestinal Crohn's disease are at increased risk of small bowel adenocarcinoma. Ulcerative colitis patients with total proctocolectomy and ileal pouch anal- anastomosis have a rather low risk of dysplasia in the ileal pouch, but the anal transition zone should be monitored periodically. Other extra intestinal cancers, such as hepatobiliary and hematopoietic cancer, have shown variable incidence rates. New endoscopic and molecular screening approaches may further refine our current surveillance guidelines and our understanding of the natural history of dysplasia.

  11. Position paper : Whole bowel irrigation

    NARCIS (Netherlands)

    2004-01-01

    Whole bowel irrigation (WBI) should not be used routinely in the management of the poisoned patient. Although some volunteer studies have shown substantial decreases in the bioavailability of ingested drugs, no controlled clinical trials have been performed and there is no conclusive evidence that W

  12. Surgery for inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    John M Hwang; Madhulika G Varma

    2008-01-01

    Despite the new and ever expanding array of medications for the treatment of inflammatory bowel disease (IBD),there are still clear indications for operative management of IBD and its complications.We present an overview of indications,procedures,considerations,and controversies in the surgical therapy of IBD.

  13. Fetal bowel anomalies - US and MR assessment

    Energy Technology Data Exchange (ETDEWEB)

    Rubesova, Erika [Stanford University, Department of Radiology, Lucile Packard Children' s Hospital, Stanford, CA (United States)

    2012-01-15

    The technical quality of prenatal US and fetal MRI has significantly improved during the last decade and allows an accurate diagnosis of bowel pathology prenatally. Accurate diagnosis of bowel pathology in utero is important for parental counseling and postnatal management. It is essential to recognize the US presentation of bowel pathology in the fetus in order to refer the patient for further evaluation or follow-up. Fetal MRI has been shown to offer some advantages over US for specific bowel abnormalities. In this paper, we review the normal appearance of the fetal bowel on US and MRI as well as the typical presentations of bowel pathologies. We discuss more specifically the importance of recognizing on fetal MRI the abnormalities of size and T1-weighted signal of the meconium-filled distal bowel. (orig.)

  14. Slow transit constipation: A functional disorder becomes an enteric neuropathy

    Institute of Scientific and Technical Information of China (English)

    Gabrio Bassotti; Vincenzo Villanacci

    2006-01-01

    Slow transit constipation has been traditionally considered and classified as a functional disorder.However, clinical and manometric evidence has been accumulating that suggests how most of the motility alterations in STC might be considered of neuropathic type. In addition, further investigations showed that subtle alterations of the enteric nervous system, not evident to conventional histological examination, may be present in these patients. In the present article we will discuss these evidences, and will try to put them in relation with the abnormal motor function of the large bowel documented in this pathological condition.

  15. Psychological Interventions for Irritable Bowel Syndrome and Inflammatory Bowel Diseases

    Science.gov (United States)

    Ballou, Sarah; Keefer, Laurie

    2017-01-01

    Psychological interventions have been designed and implemented effectively in a wide range of medical conditions, including Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Diseases (IBD). The psychological treatments for IBS and IBD with the strongest evidence base include: cognitive behavioral therapy, hypnosis, and mindfulness-based therapies. The evidence for each of these therapies is reviewed here for both IBS and IBD. In general, there is a stronger and larger evidence base to support the use of psychological interventions in IBS compared with IBD. This is likely due to the high level of psychiatric comorbidity associated with IBS and the involvement of the stress-response in symptom presentation of IBS. Further research in psychosocial interventions for IBD is necessary. Finally, the importance of conceptualizing both IBS and IBD in a biopsychosocial model is discussed and several resources for accessing Clinical Health Psychology materials and referrals are provided. PMID:28102860

  16. Effects of a 5-HT3 antagonist, ondansetron, on fasting and postprandial small bowel water content assessed by magnetic resonance imaging

    OpenAIRE

    2010-01-01

    Abstract Background 5-HT3 antagonists have been shown to be effective in relieving symptoms of IBS-D. Using a recently validated MRI method we have demonstrated reduced fasting small bowel water content (SBWC) in IBS-D associated with accelerated small bowel transit. We hypothesized that slowing of transit with ondansetron would lead to an increase in SBWC by inhibiting fasting motility. Aim To assess the effects of ondansetron compared with placebo in healthy volunteers o...

  17. Continuous spike-waves during slow waves sleep: a clinical and electroencephalografic study in fifteen children Ponta-onda contínua do sono lento: estudo clínico e eletrencefalográfico em quinze crianças

    Directory of Open Access Journals (Sweden)

    ADRIANA A. F. DJABRAIAN

    1999-09-01

    Full Text Available We report on the clinical and EEG features of 15 patients with the syndrome of "continuous spike waves during slow wave sleep" (CSWSS. The differential diagnosis of CSWSS includes benign epilepsy of childhood with centro-temporal spikes, and Landau-Kleffner and Lennox-Gastaut syndromes. We found normal CT and MRI features in 6 cases, periventricular leukomalacia with and without diffuse brain atrophy in 4 cases and hydrocephalus in 1 case. There was no association between specific neurological findings and CSWSS. Nine of our cases had relatively focal discharges, like some cases from the literature. The occurrence of CSWSS appears to be age-related, generaly between the ages of 5 to 12 years, with a strong temporal relation to the neupsychological deterioration in its nature, severity and prognosis. We believe that this striking disorder has been overlooked and that routine sleep EEG studies on epileptic children may disclose additional cases of CSWSS.Relatamos as características clínicas e eletroencefalográficas de 15 patientes com a síndrome de ponta-onda contínua do sono não-REM (POCSNR. O diagnóstico diferencial da POCSNR inclue a epilepsia benigna da infância com pontas centro-temporais e as síndromes de Landau-Kleffner e Lennox-Gastaut. Encontramos TC e RNM de crânio normais em 6 casos, leucomalácia periventricular em 4 e hidrocefalia em 1. Não houve associação de achados neurológicos específicos e a POCSNR. Nove dos nossos casos tinham descargas relativamente focais, como alguns casos da literatura. A ocorrência da POCSNR parece ser idade-dependente, geralmente entre 5 e 12 anos, com forte relação temporal à deteriorização neurocognitiva, em sua natureza, severidade e prognóstico. Acreditamos que esta síndrome tem sido pouco diagnosticada e que a realização rotineira de EEG em sono em crianças epilépticas possa revelar novos casos de POCSNR.

  18. Prebiotics and probiotics in irritable bowel syndrome and inflammatory bowel disease in children.

    Science.gov (United States)

    Guandalini, S; Cernat, E; Moscoso, D

    2015-01-01

    Underlying pathophysiological mechanisms of irritable bowel syndrome (IBS), a common disorder characterized by abdominal pain associated to a change in stool consistency or frequency, include low-grade inflammation and intestinal microbiota changes. Few and disappointing data are available for prebiotics. A few controlled trials (RCTs) of probiotics are instead available with favourable effects, although most are limited by suboptimal design and small sample size. A recent report from the Rome foundation group included 32 RCTs of probiotics, most of which showed an overall modest improvement in symptoms, with the patients most benefitting from probiotics being those with predominant diarrhoea and those having a post-infectious IBS. A review focusing only on children with functional gastrointestinal disorders concluded that probiotics are more effective than placebo in the treatment of patients with abdominal pain-related functional gastrointestinal disorders, although no effect on constipation was evident. The role for probiotics in inflammatory bowel disease (IBD) appears logical: the endogenous intestinal microbiota plays a central role in their development, and various probiotics have been found effective in animal models of IBD. However, research in humans has been overall quite limited, and it would seem that after a phase of intense research in the first decade of this century, the pace has slowed down, with fewer clinical trials been published in the past 2-3 years. To summarize current evidence: no probiotic has proven successful in Crohn's disease. In ulcerative colitis, on the other hand, data are more promising, and a very recent meta-analysis, that included 23 randomized controlled trials, concluded that there is evidence of efficacy for the probiotic mixture VSL#3 in helping inducing and maintaining remission, as well as in maintaining remission in patients with pouchitis. It is fair to state that for both IBD and IBS, more well-designed, rigorous

  19. Slowed Exports Growth

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The first half of 2010 is showing that the impacts of the financial crisis are still lingering.Zhao Jinping,a researcher at the Development Research Center of the State Council,says that the possible implementation of exit strategies in developed countries may deal a heavy blow to a global rally,and it will certainly result in slowed exports growth for China.Zhao published his opinion in the China Economic Times.The first part was published in issue No.33.Edited excerpts of the second part follow:

  20. Therapeutic modalities for the short bowel syndrome : improvement of adaptation and small-bowel transplantation

    NARCIS (Netherlands)

    M.C.J. Wolvekamp

    1994-01-01

    textabstractThis thesis deals with two therapeutic modalities for patients with an irreversible short bowel syndrome: improvement of adaptation and small-bowel transplantation. Thereby, emphasis is put on the role of these therapeutic modalities for children.

  1. Heritability in inflammatory bowel disease

    DEFF Research Database (Denmark)

    Gordon, Hannah; Trier Moller, Frederik; Andersen, Vibeke

    2015-01-01

    Since Tysk et al's pioneering analysis of the Swedish twin registry, twin and family studies continue to support a strong genetic basis of the inflammatory bowel diseases. The coefficient of heritability for siblings of inflammatory bowel disease probands is 25 to 42 for Crohn's disease and 4 to 15...... for ulcerative colitis. Heritability estimates for Crohn's disease and ulcerative colitis from pooled twin studies are 0.75 and 0.67, respectively. However, this is at odds with the much lower heritability estimates from Genome-Wide Association Studies (GWAS). This "missing heritability" is likely due...... to shortfalls in both family studies and GWAS. The coefficient of heritability fails to account for familial shared environment. Heritability calculations from twin data are based on Falconer's method, with premises that are increasingly understood to be flawed. GWAS based heritability estimates may...

  2. Neuroinflammation in inflammatory bowel disease

    OpenAIRE

    Kirchgessner Annette; Lakhan Shaheen E

    2010-01-01

    Abstract Inflammatory bowel disease is a chronic intestinal inflammatory condition, the pathology of which is incompletely understood. Gut inflammation causes significant changes in neurally controlled gut functions including cramping, abdominal pain, fecal urgency, and explosive diarrhea. These symptoms are caused, at least in part, by prolonged hyperexcitability of enteric neurons that can occur following the resolution of colitis. Mast, enterochromaffin and other immune cells are increased...

  3. Short bowel syndrome in adults

    DEFF Research Database (Denmark)

    Matarese, Laura E; Jeppesen, Palle B; O'Keefe, Stephen J D

    2014-01-01

    Short bowel syndrome (SBS) is a heterogeneous disorder with broad variation in disease severity arising from different types of intestinal resection. The spectrum of malabsorption ranges from intestinal insufficiency to intestinal failure. Individualized patient strategies involving modifications...... long-term dependency on parenteral support (PS) for nutrition and fluid requirements. Specialized IR programs employ team-based interdisciplinary approaches to coordinate individualized patient care and treatment management through centralized facilities. Such facilities are often specialized...

  4. Comorbidity in inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Antonio López San Román; Fernando Mu(n)oz

    2011-01-01

    Patients with inflammatory bowel disease (IBD) can be affected by other unrelated diseases. These are called comorbid conditions, and can include any secondary health problem that affects a person suffering from a primary or main disease, and which is neither linked physiopathologically to the primary condition, nor is it due to the treatments used for the primary condition or to its long-term anatomical or physiological consequences.Different comorbid conditions, as well as their influence on IBD, are discussed.

  5. Nutritive support in short Bowel syndrome (sbs

    Directory of Open Access Journals (Sweden)

    Simić Dušica

    2003-01-01

    Full Text Available Short bowel syndrome most commonly result after bowel resection for necrosis of the bowel. It may be caused by arterial or venous thrombosis, volvolus and in children, necrotizing enterocolitis. The other causes are Crohn,s disease intestinal atresia. The factors influencing the risk on short bowel syndrome are the remaining length of the small bowel, the age of onset, the length of the colon, the presence or absence of the ileo-coecal valve and the time after resection. Besides nutritional deficiencies there some other consequences of extensive resections of the small intestine (gastric acid hypersecretion, d-lactic acidosis, nephrolithiasis, cholelithiasis, which must be diagnosed, treated, and if possible, prevented. With current therapy most patients with short bowel have normal body mass index and good quality of life.

  6. Functional bowel symptoms and diet.

    Science.gov (United States)

    Gibson, P R; Barrett, J S; Muir, J G

    2013-10-01

    It is well recognised that ingestion of food is a trigger for functional bowel symptoms, particularly those associated with irritable bowel syndrome (IBS). Patients often use manipulation of diet as a means of controlling symptoms. Despite description of multiple dietary methods, few have scientific backing or quality evidence of efficacy. One approach is to define how specific food components influence the pathophysiology of IBS and then rationally design dietary approaches. For example, short-chain poorly absorbed carbohydrates (fermentable oligo-, di- and mono-saccharides and polyols (FODMAP)) cause luminal distension, which is a major stimulus for the development of symptoms in patients with visceral hypersensitivity. By determining food content of FODMAP, a diet in which foods low in FODMAP are favoured over those high in FODMAP can be designed. Observational, comparative and randomised controlled treatment and rechallenge studies have shown that such an approach is efficacious in the majority of patients with IBS. The low FODMAP diet is now the primary dietary therapy for such patients. Similar approaches can be applied to other food components, including proteins (such as gluten), fats and natural bioactive food chemicals. Such approaches have suggestions of efficacy, but the evidence base remains underdeveloped. An additional and important consideration for any dietary therapy is its nutritional adequacy and potential adverse health effects. Dietary manipulation is now a key management strategy in patients with functional bowel symptoms. Future well-designed interventional studies will lead to refinement of dietary approaches taken and to a better understanding of their long-term safety.

  7. Small-bowel permeability in collagenous colitis

    DEFF Research Database (Denmark)

    Wildt, Signe; Madsen, Jan L; Rumessen, Jüri J

    2006-01-01

    OBJECTIVE: Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small-intestin......OBJECTIVE: Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small...

  8. Slow and fast light in semiconductor waveguides

    DEFF Research Database (Denmark)

    Mørk, Jesper; Hansen, Per Lunnemann; Xue, Weiqi

    2010-01-01

    Investigations of slow and fast light effects in semiconductor waveguides entail interesting physics and point to a number of promising applications. In this review we give an overview of recent progress in the field, in particular focusing on the physical mechanisms of electromagnetically induced...... transparency and coherent population oscillations. While electromagnetically induced transparency has been the most important effect in realizing slowdown effects in atomic gasses, progress has been comparatively slow in semiconductors due to inherent problems of fast dephasing times and inhomogeneous...... broadening in quantum dots. The physics of electromagnetically induced transparency in semiconductors is discussed, emphasizing these limitations and recent suggestions for overcoming them. On the other hand, the mechanism of coherent population oscillations relies on wave mixing effects and is well suited...

  9. Slowed Exports Growth

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Ⅲ. Slowed export recovery in the second half Since the beginning of this year, global trade has maintained a recovery growth thanks to the worldwide economic rally.From January to April, the imports of three major Economics--the United States, the euro zone and Japan--rose 17.5 percent on average from a year ago. Import growths for the United States, the euro zone and Japan were 20.9 percent, 4.8 percent and 29 percent, respectively, which spurred China's exports to those regions. From January to June this year, China's exports totaled $705.09 billion, up 35.2 percent from the same period in 2009 and were 5.8 percent higher than the first half of 2008 when the crisis had yet to begin. Those figures indicated China's exports had rebounded to precrisis levels.

  10. Slow change deafness.

    Science.gov (United States)

    Neuhoff, John G; Wayand, Joseph; Ndiaye, Mamoudou C; Berkow, Ann B; Bertacchi, Breanna R; Benton, Catherine A

    2015-05-01

    In four experiments, we demonstrated a new phenomenon called "slow-change deafness." In Experiment 1 we presented listeners with continuous speech that changed three semitones in pitch over time, and we found that nearly 50 % failed to notice the change. Experiments 2 and 3 replicated the finding, demonstrated that the changes in the stimuli were well above threshold, and showed that when listeners were alerted to the possibility of a change, detection rates improved dramatically. Experiment 4 showed that increasing the magnitude of the change that occurred in the stimulus decreased the rate of change deafness. Our results are consistent with previous work that had shown that cueing listeners to potential auditory changes can significantly reduce change deafness. These findings support an account of change deafness that is dependent on both the magnitude of a stimulus change and listener expectations.

  11. Slow Scan Telemedicine

    Science.gov (United States)

    1984-01-01

    Originally developed under contract for NASA by Ball Bros. Research Corporation for acquiring visual information from lunar and planetary spacecraft, system uses standard closed circuit camera connected to a device called a scan converter, which slows the stream of images to match an audio circuit, such as a telephone line. Transmitted to its destination, the image is reconverted by another scan converter and displayed on a monitor. In addition to assist scans, technique allows transmission of x-rays, nuclear scans, ultrasonic imagery, thermograms, electrocardiograms or live views of patient. Also allows conferencing and consultation among medical centers, general practitioners, specialists and disease control centers. Commercialized by Colorado Video, Inc., major employment is in business and industry for teleconferencing, cable TV news, transmission of scientific/engineering data, security, information retrieval, insurance claim adjustment, instructional programs, and remote viewing of advertising layouts, real estate, construction sites or products.

  12. Inflammatory bowel disease: beyond the boundaries of the bowel.

    Science.gov (United States)

    Actis, Giovanni C; Rosina, Floriano; Mackay, Ian R

    2011-06-01

    Dysregulated inflammation in the gut, designated clinically as inflammatory bowel disease (IBD), is manifested by the prototypic phenotypes of an Arthus-like reaction restricted to the mucosa of the colon, as in ulcerative colitis, or a transmural granulomatous reaction, as in Crohn's disease, or an indeterminate form of the two polar types. That the inflammation of IBD can trespass the boundaries of the bowel has long been known, with articular, ophthalmologic, cutaneous, hepatobiliary or other complications/associations - some autoimmune and others not - affecting significant numbers of patients with IBD. Also notable is the frequency of diagnosis of IBD-type diseases on a background of systemic, (mostly myelo-hematological) disorders, associated with alterations of either (or both) innate or adaptive arms of the immune response. Finally, cases of IBD are reported to occur as an adverse effect of TNF inhibitors. Bone marrow transplant has been proven to be the only curative measure for some of the above cases. Thus, in effect, the IBDs should now be regarded as a systemic, rather than bowel-localized, disease. Genome-wide association studies have been informative in consolidating the view of three phenotypes of IBD (ulcerative colitis, Crohn's disease and mixed) and, notably, are revealing that the onset of IBD can be linked to polymorphisms in regulatory miRNAs, or to nucleotide sequences coding for regulatory lymphokines and/or their receptors. At the effector level, we emphasize the major role of the Th17/IL-23 axis in dictating the perpetuation of intestinal inflammation, augmented by a failure of physiological control by regulatory T-cells. In conclusion, there is a central genesis of the defects underlying IBD, which therefore, in our opinion, is best accommodated by the concept of IBD as more of a syndrome than an autonomous disease. This altered mindset should upgrade our knowledge of IBD, influence its medical care and provide a platform for further

  13. Segmental reversal of the small bowel as treatment of short bowel syndrome in adults

    DEFF Research Database (Denmark)

    Burgdorf, Stefan K; Qvist, Niels; Gögenur, Ismail

    2014-01-01

    Short bowel syndrome is the result of extensive surgical resection, inherited defects or loss of functional absorbing intestine. Parenteral nutrition is associated with high economical expenses, increased morbidity and decreased quality of life. Intestinal transplantation is associated with high...... morbidity and mortality rates. Segmental reversal of the small bowel can prolong the transit time in the small bowel and in many cases permanently end parenteral nutrition dependency. Segmental reversal of the small bowel should be integrated in the surgical treatment of adults with short bowel syndrome....

  14. Update imaging in inflammatory bowel diseases.

    Science.gov (United States)

    Herfarth, Hans

    2013-01-01

    Imaging is a central component of the diagnostic process in inflammatory bowel diseases. This review summarizes the recent progress of various most commonly used imaging modalities including computed tomography enterography, magnetic resonance enterography and capsule endoscopy. Advantages and disadvantages of each imaging protocol in suspected and established inflammatory bowel diseases are reviewed and brought into context in proposed diagnostic algorithms.

  15. Hypertrophic osteoarthropathy of chronic inflammatory bowel disease

    Energy Technology Data Exchange (ETDEWEB)

    Oppenheimer, D.A.; Jones, H.H.

    1982-12-01

    The case of a 14-year old girl with painful periostitis and ulcerative colitis is reported. The association of chronic inflammatory bowel disease with osteoarthropathy is rare and has previously been reported in eight patients. The periosteal reaction found in association with inflammatory bowel disease is apparently related to a chronic disease course and may cause extreme localized pain.

  16. Small bowel transplantation : immunological and functional studies

    NARCIS (Netherlands)

    R.W.F. de Bruin (Ron)

    1993-01-01

    textabstractSmall bowel transplantation (SBT) would be the treatment of choice for patients suffering from the short bowel syndrome. Although in some centers SBT in patients is done with a considerable degree of success (Grant et al 1990, Todo et al. 1992), it is by no means an established and widel

  17. Familial occurrence of inflammatory bowel disease

    DEFF Research Database (Denmark)

    Orholm, M; Munkholm, P; Langholz, E;

    1991-01-01

    BACKGROUND AND METHODS: We assessed the familial occurrence of inflammatory bowel disease in Copenhagen County, where there has been a long-term interest in the epidemiology of such disorders. In 1987 we interviewed 662 patients in whom inflammatory bowel disease had been diagnosed before 1979...

  18. Small-bowel permeability in collagenous colitis

    DEFF Research Database (Denmark)

    Wildt, Signe; Madsen, Jan L; Rumessen, Jüri J

    2006-01-01

    Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small-intestinal biopsies...

  19. Pregnancy outcome in inflammatory bowel disease

    DEFF Research Database (Denmark)

    Bortoli, A; Pedersen, N; Duricova, D;

    2011-01-01

    Inflammatory bowel disease (IBD) frequently affects women during their reproductive years. Pregnancy outcome in women with IBD is well described, particularly in retrospective studies.......Inflammatory bowel disease (IBD) frequently affects women during their reproductive years. Pregnancy outcome in women with IBD is well described, particularly in retrospective studies....

  20. Small Bowel Review: Part II

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    1996-01-01

    Full Text Available Major scientific advances have been made over the past few years in the areas of small bowel physiology, pathology, microbiology and clinical sciences. Over 1000 papers have been reviewed and a selective number are considered here. Wherever possible, the clinical relevance of these advances have been identified. Topics discussed are enterocyte proliferation and growth factors; amino acids, peptides and allergies; motility; salt and water absorption and secretion – diarrhea; vitamins and minerals; early development and ageing of the intestine; and ethanol effects.

  1. Immunopathogenesis of inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    David Q Shih; Stephan R Targan

    2008-01-01

    Crohn's disease and ulcerative colitis are chronic relapsing immune mediated disorders that results from an aberrant response to gut luminal antigen in genetically susceptible host. The adaptive immune response that is then triggered was widely considered to be a T-helper-1 mediated condition in Crohn's disease and T-helper-2 mediated condition in ulcerative colitis. Recent studies in animal models, genome wide association, and basic science has provided important insights in in the immunopathogenesis of inflammatory bowel disease, one of which was the characterization of the interleukin-23/Th-17 axis.

  2. Small Bowel Review: Part I

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    2000-01-01

    Full Text Available In the past year, there have been many advances in the area of small bowel physiology and pathology. More than 1500 papers were assessed in preparation for this review. Some were selected and reviewed, with a particular focus on presenting clinically useful information for the practising gastroenterologist. Relevant review articles have been highlighted, and important clinical learning points have been stressed. The topics are varied in scope, and wherever possible show a logical progression from basic physiology to pathophysiology to clinical disorders and management.

  3. Adhesive bowel obstruction? Not always

    Directory of Open Access Journals (Sweden)

    Mittapalli D

    2011-01-01

    Full Text Available A 58-year-old man presented acutely with features of post-surgical adhesive small bowel obstruction. Following an unsuccessful trial of conservative management, computed tomography (CT of the abdomen was performed. This revealed a mass in the ileocaecal region, for which he underwent a subsequent right hemicolectomy. Histology revealed diffuse B-cell Non-Hodgkin′s lymphoma of the terminal ileum. Confounding obstructive lesion of the intestine in patients with a history of previous laparotomy is extremely uncommon. Early high resolution imaging may predict diagnosis and consolidate clinical management plans.

  4. Inflammatory Bowel Disease and Thrombosis

    Directory of Open Access Journals (Sweden)

    Ahmet Tezel

    2012-06-01

    Full Text Available Inflammatory Bowel Disease (IBD is a group of chronic and relapsing inflammatory disorders of the gastrointestinal system. In these cases, findings are detected in extraintestinal systems also. There is a tendency for thrombotic events in IBD, as in the other inflammatory processes. The pathogenesis of this thrombotic tendency is multidimensional, including lack of natural anticoagulants, prothrombotic media induced via the inflammatory process, long-term sedentary life style, steroid use, surgery, and catheter placement. The aim of this review was to highlight the positive relationship between IBD and thrombotic events, and the proper treatment of at-risk patients.

  5. Irritable bowel syndrome: contemporary nutrition management strategies.

    Science.gov (United States)

    Mullin, Gerard E; Shepherd, Sue J; Chander Roland, Bani; Ireton-Jones, Carol; Matarese, Laura E

    2014-09-01

    Irritable bowel syndrome is a complex disorder whose pathophysiology involves alterations in the enteric microbiota, visceral hypersensitivity, gut immune/barrier function, hypothalamic-pituitary-adrenal axis regulation, neurotransmitters, stress response, psychological factors, and more. The importance of diet in the management of irritable bowel syndrome has taken center stage in recent times as the literature validates the relationship of certain foods with the provocation of symptoms. Likewise, a number of elimination dietary programs have been successful in alleviating irritable bowel syndrome symptoms. Knowledge of the dietary management strategies for irritable bowel syndrome will help guide nutritionists and healthcare practitioners to deliver optimal outcomes. This tutorial reviews the nutrition management strategies for irritable bowel syndrome.

  6. A Case for Slow Reading

    Directory of Open Access Journals (Sweden)

    Matthew J Ostercamp

    2014-05-01

    Full Text Available This essay makes a case for the value of slow or deep reading.  Inspired by the Slow Food movement it seeks to apply their principles to reading.  It begins by exploring the meaning of information and how like food, information has come to be regarded as a commodity.  Drawing upon the philosophy of Albert Borgmann, it counters the prevalent commodity view of information by offering an alternative paradigm that connects careful reading to human flourishing.  It argues that by connecting information to pleasure and community, slow reading advocates can have comparable success to that enjoyed by the slow food movement.

  7. Slow light and slow acoustic phonons in optophononic resonators

    Science.gov (United States)

    Villafañe, V.; Soubelet, P.; Bruchhausen, A. E.; Lanzillotti-Kimura, N. D.; Jusserand, B.; Lemaître, A.; Fainstein, A.

    2016-11-01

    Slow and confined light have been exploited in optoelectronics to enhance light-matter interactions. Here we describe the GaAs/AlAs semiconductor microcavity as a device that, depending on the excitation conditions, either confines or slows down both light and optically generated acoustic phonons. The localization of photons and phonons in the same place of space amplifies optomechanical processes. Picosecond laser pulses are used to study through time-resolved reflectivity experiments the coupling between photons and both confined and slow acoustic phonons when the laser is tuned either with the cavity (confined) optical mode or with the stop-band edge (slow) optical modes. A model that fully takes into account the modified propagation of the acoustic phonons and light in these resonant structures is used to describe the laser detuning dependence of the coherently generated phonon spectra and amplitude under these different modes of laser excitation. We observe that confined light couples only to confined mechanical vibrations, while slow light can generate both confined and slow coherent vibrations. A strong enhancement of the optomechanical coupling using confined photons and vibrations, and also with properly designed slow photon and phonon modes, is demonstrated. The prospects for the use of these optoelectronic devices in confined and slow optomechanics are addressed.

  8. [Inflammatory Bowel Disease Competence Network].

    Science.gov (United States)

    Schreiber, Stefan; Hartmann, Heinz; Kruis, Wolfgang; Kucharzik, Torsten; Mudter, Jonas; Siegmund, Britta; Stallmach, Andreas; Witte, Christine; Fitzke, Klaus; Bokemeyer, Bernd

    2016-04-01

    The Inflammatory Bowel Disease Competence Network is a network of more than 500 physicians and scientists from university clinics, hospitals and gastroenterology practices. The focus extends from the two major forms of inflammatory bowel diseases, Crohn's disease and ulcerative colitis, into other chronic inflammatory conditions affecting the intestine, including coeliac disease and microscopic colitis. The network translates basic science discoveries (in particular in the molecular epidemiology research) into innovative diagnostics and therapy. Through its strong networking structures it supports a continuous process to improve quality and standardisation in patient care that is implemented in close interaction with European networks addressing this disease group.Optimisation of patient care based on scientifically proven evidence is a main focus of the network. Therefore, it supports and coordinates translational research and infrastructure projects that investigate aetiology, improvement of diagnostic methods, and development of new or improved use of established therapies. Members participate in various training projects, thus ensuring the rapid transfer of research results into clinical practice.The competence network cooperates with the main patient organisations to engage patients in all levels of activities. The network and the patient organisations have interest in promoting public awareness about the disease entities, because their importance and burden is underestimated in non-specialised medical fields and among the general public.

  9. An analytical method of metal periodic slow-wave structure for rectangular cross-section Cerenkov maser%一种矩形截面切伦柯夫脉塞金属周期慢波结构的分析方法

    Institute of Scientific and Technical Information of China (English)

    舒雯; 赵鼎; 王勇

    2011-01-01

    分析了矩形截面切伦柯夫脉塞周期金属慢波结构的色散特性,以及结构参数的变化对色散曲线的影响.为避免慢波结构两端突变引起的反射振荡,采用等效电路法分析了用于连接光滑波导和慢波结构的渐变段.将线性形、两段形和指数形的渐变段进行了比较.指数形渐变段末端的功率反射系数最小,并且整体的变化最平缓,因此可将其作为实现慢波与快波间转换的较优选择.分析了频率和实际加工误差对指数形渐变段功率反射系数的影响:在频率较小时,功率反射系数也较小;固定频率下,较小的加工误差能使交界处功率反射系数的变化较平缓.在此基础上设计了一个功率反射系数小于0.01的指数渐变段,实现了工作模式和快波模式之间的良好匹配.与耦合模理论分析方法相比,等效电路方法更为简洁,二者结果相符合.%The dispersion characteristics of metal periodic slow-wave structure in rectangular cross-section Cerenkov maser have been analyzed. The effects of the geometrical parameters on the dispersion curves were investigated. In order to avoid the reflect oscillation induced by the changes at two ends of the slow-wave structure, the taper for matching the smooth waveguide and the slow-wave structure was analyzed by use of equivalent circuit method. Through comparing the linear, the two-piece linear and the exponential tapers, we know that the exponential taper gives the lowest total power reflection coefficient at the end, and the total change is mild. So the exponential taper can be used as an optimal solution for transition between slow and fast modes. The effects of frequency and fabrication error to the exponential taper were analyzed. The lower the frequency is, the lower the total power reflection coefficient is. Under the same frequency, the lower fabrication errors smooth the abrupt jumps of the total power reflection coefficient. With this analysis

  10. Method for monitoring slow dynamics recovery

    Science.gov (United States)

    Haller, Kristian C. E.; Hedberg, Claes M.

    2012-11-01

    Slow Dynamics is a specific material property, which for example is connected to the degree of damage. It is therefore of importance to be able to attain proper measurements of it. Usually it has been monitored by acoustic resonance methods which have very high sensitivity as such. However, because the acoustic wave is acting both as conditioner and as probe, the measurement is affecting the result which leads to a mixing of the fast nonlinear response to the excitation and the slow dynamics material recovery. In this article a method is introduced which, for the first time, removes the fast dynamics from the process and allows the behavior of the slow dynamics to be monitored by itself. The new method has the ability to measure at the shortest possible recovery times, and at very small conditioning strains. For the lowest strains the sound speed increases with strain, while at higher strains a linear decreasing dependence is observed. This is the first method and test that has been able to monitor the true material state recovery process.

  11. Coronal Waves and Oscillations

    Directory of Open Access Journals (Sweden)

    Nakariakov Valery M.

    2005-07-01

    Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.

  12. Towards an integrated psychoneurophysiological approach of irritable bowel syndrome

    NARCIS (Netherlands)

    Veek, Patrick Petrus Johannes van der

    2009-01-01

    Irritable bowel syndrome (IBS) is a functional bowel disorder characterized by recurrent abdominal pain or discomfort accompanied by disturbed bowel habits. It is among the most frequently occurring functional bowel syndromes, but the pathophysiology is poorly understood. A variety of mechanisms hav

  13. Slow light based on material and waveguide dispersion

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Lavrinenko, Andrei; Mørk, Jesper

    2009-01-01

    We study slow light pulse propagation in a photonic crystal structure consisting of a dispersive and absorptive dielectric material and compare it with the constant wave case. The group index and the trasmission are investigated for the example of an ensemble of semiconductor quantum dots embedded...

  14. Musculoskeletal Manifestations in Inflammatory Bowel Disease

    Directory of Open Access Journals (Sweden)

    Giovanni Fornaciari

    2001-01-01

    Full Text Available Muscoloskeletal manifestations are the most common extraintestinal complications of inflammatory bowel disease. Wide ranges in prevalence have been reported, depending on the criteria used to define spondylarthropathy. In 1991, the European Spondylarthropathy Study Group developed classification criteria that included previously neglected cases of undifferentiated spondylarthropathies, which had been ignored in most of the oldest epidemiological studies on inflammatory bowel disease. The spectrum of muscoloskeletal manifestations in inflammatory bowel disease patients includes all of the clinical features of spondylarthropathies: peripheral arthritis, inflammatory spinal pain, dactylitis, enthesitis (Achilles tendinitis and plantar fasciitis, buttock pain and anterior chest wall pain. Radiological evidence of sacroiliitis is common but not obligatory. The articular manifestations begin either concomitantly or subsequent to the bowel disease; however, the onset of spinal disease often precedes the diagnosis of inflammatory bowel disease. The prevalence of the different muscoloskeletal manifestations is similar in ulcerative colitis and Crohn's disease. Symptoms usually disappear after proctocolectomy. The pathogenetic mechanisms that produce the muscoloskeletal manifestations in inflammatory bowel disease are unclear. Several arguments favour an important role of the intestinal mucosa in the development of spondylarthropathy. The natural history is characterized by periods of flares and remission; therefore, the efficacy of treatment is difficult to establish. Most patients respond to rest, physical therapy and nonsteroidal anti-inflammatory drugs, but these drugs may activate bowel disease. Sulphasalazine may be recommended in some patients. There is no indication for the systemic use of steroids.

  15. Surgical management of short bowel syndrome.

    Science.gov (United States)

    Iyer, Kishore R

    2014-05-01

    For patients with short bowel syndrome (SBS), surgery can play an important role in preventing, mitigating, and, in some cases, reversing intestinal failure (IF). During intestinal resection, bowel length should be conserved to the fullest extent possible to avoid dependence on parenteral nutrition (PN). Bowel salvage may be improved by initially preserving tissue of questionable viability and later reevaluating during "second-look" procedures. Once the patient is stabilized, ostomy reversal and recruitment of distal unused bowel should be prioritized whenever feasible. Following progression to IF, surgical management of SBS depends on the symptoms and anatomical characteristics of the individual patient. For carefully selected patients with rapid intestinal transit and dilated bowel, longitudinal intestinal lengthening and tailoring (LILT) and serial transverse enteroplasty (STEP) procedures may provide benefit. Outcomes following STEP and LILT are generally similar, and the choice between these procedures may rest on surgeon preference. For patients with rapid intestinal transit in the absence of bowel dilation, segmental reversal of the small bowel may reduce PN requirements. Intestinal transplantation is the standard of care for patients in whom intestinal rehabilitation attempts have failed and who are at risk of life-threatening complications of PN. Because patients awaiting isolated intestine transplant show increased survival compared with patients awaiting combined intestine-liver transplant, early referral of appropriate patients, before the development of advanced liver disease, is critical to enhancing patient outcomes.

  16. Slow Tourism: Exploring the discourses

    Directory of Open Access Journals (Sweden)

    J. Guiver

    2016-05-01

    Full Text Available ‘Slow travel’ and ‘slow tourism’ are relatively new, but contested, concepts. This paper examines the meanings ascribed to them in the academic literature and websites targeted at potential tourists. It finds concurrence on aspects of savouring time at the destination and investing time to appreciate the locality, its people, history, culture and products, but detects different emphases. The academic literature stresses the benefits to the destination and global sustainability, while the websites focus on the personal benefits and ways of becoming a ‘slow tourist’. Food and drink epitomise the immersion in and absorption of the destination and the multi-dimensional tourism experience, contrasted with the superficiality of mainstream tourism. The paper discusses whether tourists practising slow tourism without using the label are slow tourists or not.

  17. Bowel-associated dermatosis-arthritis syndrome in an adolescent with short bowel syndrome.

    Science.gov (United States)

    Pereira, Ester; Estanqueiro, Paula; Almeida, Susana; Ferreira, Ricardo; Tellechea, Oscar; Salgado, Manuel

    2014-09-01

    Bowel-associated dermatosis-arthritis syndrome (BADAS) is a neutrophilic dermatosis, characterized by the occurrence of arthritis and skin lesions related to bowel disease with or without bowel bypass. We report an unusual case of BADAS in a 15-year-old white male with congenital aganglionosis of the colon and hypoganglionosis of the small intestine and multiple bowel surgeries in childhood complicated by short bowel syndrome. He presented with recurrent peripheral polyarthritis, tenosynovitis, and painful erythematous subcutaneous nodules located on the dorsolateral regions of the legs and on the dorsa of the feet. Histological examination disclosed a neutrophilic dermatosis confirming the diagnosis of BADAS.Although an uncommon disease, especially at pediatric age, it is important to evoke the diagnosis of BADAS in children and adolescents with bowel disease, because treatment options and prognosis are distinct from other rheumatologic conditions.

  18. Efficient and safe small-bowel adhesiolysis.

    Science.gov (United States)

    Klasen, Jennifer; Wenning, Anna; Storni, Federico; Angst, Eliane; Gloor, Beat

    2014-01-01

    Small-intestine adhesiolysis can be very time consuming and may be associated with bowel wall damage. The risk for injuries to the small or large bowel resulting in increased morbidity and costs is considerable. Both efficient and gentle dissection of adhesions is important in order to avoid intraoperative perforation or, worse, postoperative intestinal leaks. We present a technique using drops of body-warm isotonic saline solution to create an edematous swelling of the adhesions. This procedure not only protects the bowel from cooling and drying, but also simplifies the dissection and, thus, lowers the risk of intestinal lesions.

  19. Novel susceptibility genes in inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Colin Noble; Elaine Nimmo; Daniel Gaya; Richard K Russell; Jack Satsangi

    2006-01-01

    The inflammatory bowel disease, Crohn's disease and ulcerative colitis, are polygenic disorders with important environmental interactions. To date, the most widely adopted approach to identifying susceptibility genes in complex diseases has involved genome wide linkage studies followed by studies of positional candidate genes in loci of interest. This review encompasses data from studies into novel candidate genes implicated in the pathogenesis of inflammatory bowel disease. Novel techniques to identify candidate genes-genome wide association studies, yeast-two hybrid screening, microarray gene expression studies and proteomic profiling,are also reviewed and their potential role in unravelling the pathogenesis of inflammatory bowel disease are discussed.

  20. Management of short bowel syndrome in infancy.

    Science.gov (United States)

    Batra, A; Beattie, R M

    2013-11-01

    Short bowel syndrome (SBS) is a reduction in functioning bowel length which is most often a result of surgical resection. Risk factors in the neonatal period include necrotising enterocolitis, small bowel atresia and gastroschisis. With increasing survival of preterm infants there is an increase in incidence. Management is dependent on the use of parenteral nutrition to maintain fluid and electrolyte homeostasis and promote growth and development with the longer term aim being to promote intestinal adaptation to achieve partial or complete enteral autonomy. In this review we discuss the incidence, aetiology, pathophysiology, medical and surgical treatments and outcome.

  1. An overview of short bowel syndrome management: adherence, adaptation, and practical recommendations.

    Science.gov (United States)

    Wall, Elizabeth A

    2013-09-01

    Short bowel syndrome (SBS) refers to the clinical consequences resulting from loss of small bowel absorptive surface area due to surgical resection or bypass. The syndrome is characterized by maldigestion, malabsorption, and malnutrition. Survival of patients with SBS is dependent on adaptation in the remaining bowel and a combination of pharmacologic and nutrition therapies. Individual plans of care are developed based on the length and sites of remaining bowel, the degree of intestinal adaptation, and the patient's ability to adhere to the medication and dietary regimens. Antisecretory and antidiarrheal medications are prescribed to slow intestinal transit times and optimize fluid and nutrient absorption. Based on postsurgical anatomy, enteral feedings, parenteral infusions, complex diet plans, and vitamin and mineral supplementation are used in various combinations to nourish patients with SBS. In the acute care setting, registered dietitians (RDs) assist with infusion therapy, diet education, and discharge planning. Long-term, as the small intestine adapts, RDs revise the nutrition care plan and monitor for nutrient deficiencies, metabolic bone disease, and anemia. The frequent monitoring and revision of care plans, plus the appreciable benefits from proper medical nutrition therapy, make this patient population extremely challenging and rewarding for RDs to manage. This article provides a brief, case study-based overview of the medical and nutrition management of SBS.

  2. Probiotics and irritable bowel syndrome.

    Science.gov (United States)

    Dai, Cong; Zheng, Chang-Qing; Jiang, Min; Ma, Xiao-Yu; Jiang, Li-Juan

    2013-09-28

    Irritable bowel syndrome (IBS) is common gastrointestinal problems. It is characterized by abdominal pain or discomfort, and is associated with changes in stool frequency and/or consistency. The etiopathogenesis of IBS may be multifactorial, as is the pathophysiology, which is attributed to alterations in gastrointestinal motility, visceral hypersensitivity, intestinal microbiota, gut epithelium and immune function, dysfunction of the brain-gut axis or certain psychosocial factors. Current therapeutic strategies are often unsatisfactory. There is now increasing evidence linking alterations in the gastrointestinal microbiota and IBS. Probiotics are living organisms which, when ingested in certain numbers, exert health benefits beyond inherent basic nutrition. Probiotics have numerous positive effects in the gastrointestinal tract. Recently, many studies have suggested that probiotics are effective in the treatment of IBS. The mechanisms of probiotics in IBS are very complex. The purpose of this review is to summarize the evidence and mechanisms for the use of probiotics in the treatment of IBS.

  3. Disturbances in small bowel motility.

    LENUS (Irish Health Repository)

    Quigley, E M

    2012-02-03

    Recently, the small intestine has become the focus of investigation as a potential site of dysmotility in the irritable bowel syndrome (IBS). A number of motor abnormalities have been defined in some studies, and include \\'clustered\\' contractions, exaggerated post-prandial motor response and disturbances in intestinal transit. The significance of these findings remains unclear. The interpretation of available studies is complicated by differences in subject selection, the direct influence of certain symptoms, such as diarrhoea and constipation, and the interference of compounding factors, such as stress and psychopathology. Dysmotility could also reflect autonomic dysfunction, disturbed CNS control and the response to heightened visceral sensation or central perception. While motor abnormalities may not explain all symptoms in IBS, sensorimotor interactions may be important in symptom pathogenesis and deserve further study.

  4. Changes of smooth muscle contractile filaments in small bowel atresia

    Institute of Scientific and Technical Information of China (English)

    Stefan Gfroerer; Henning Fiegel; Priya Ramachandran; Udo Rolle; Roman Metzger

    2012-01-01

    AIM:To investigate morphological changes of intestinal smooth muscle contractile fibres in small bowel atresia patients.METHODS:Resected small bowel specimens from small bowel atresia patients (n =12) were divided into three sections (proximal,atretic and distal).Standard histology hematoxylin-eosin staining and enzyme immunohistochemistry was performed to visualize smooth muscle contractile markers α-smooth muscle actin (SMA) and desmin using conventional paraffin sections of the proximal and distal bowel.Small bowel from agematched patients (n =2) undergoing Meckel's diverticulum resection served as controls.RESULTS:The smooth muscle coat in the proximal bowel of small bowel atresia patients was thickened compared with control tissue,but the distal bowel was unchanged.Expression of smooth muscle contractile fibres SMA and desmin within the proximal bowel was slightly reduced compared with the distal bowel and control tissue.There were no major differences in the architecture of the smooth muscle within the proximal bowel and the distal bowel.The proximal and distal bowel in small bowel atresia patients revealed only minimal differences regarding smooth muscle morphology and the presence of smooth muscle contractile filament markers.CONCLUSION:Changes in smooth muscle contractile filaments do not appear to play a major role in postoperative motility disorders in small bowel atresia.

  5. Multidetector row computed tomography in bowel obstruction. Part 2. Large bowel obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, R. [Department of Radiology, Glenfield Hospital, Leicester (United Kingdom)]. E-mail: rakesh.sinha@uhl-tr.nhs.uk; Verma, R. [Department of Radiology, Glenfield Hospital, Leicester (United Kingdom)

    2005-10-01

    Large bowel obstruction may present as an emergency as high-grade colonic obstruction and can result in perforation. Perforated large bowel obstruction causes faecal peritonitis, which can result in high morbidity and mortality. Multidetector row computed tomography (MDCT) has the potential of providing an accurate diagnosis of large bowel obstruction. The rapid acquisition of images within one breath-hold reduces misregistration artefacts than can occur in critically ill or uncooperative patients. The following is a review of the various causes of large bowel obstruction with emphasis on important pathogenic factors, CT appearances and the use of multiplanar reformatted images in the diagnostic workup.

  6. Balb/c小鼠小肠Cajal间质细胞形态学特征及慢波活动的研究%Study on morphological feature of interstitial cells of Cajal and slow waves in Balb/c murine small intestine

    Institute of Scientific and Technical Information of China (English)

    贾后军; 刘宝华; 童卫东; 张连阳; 文亚渊; 刘建仓

    2006-01-01

    [Objective] To observe the distribution and morphology of interstitial cells of Cajal (ICC) in young Balb/c murine small intestine and determine the activities of slow waves, and to recognize the development of ICC more clearly. [Methods] Firstly, the distribution and configuration of ICC were observed with immunohistochemical method and the ultrastructure of ICC was observed by an electron microscope in the small intestine of 10-days postpartum Balb/c murine. Secondly, the slow waves of small intestine in vivo were measured in 10-days postpartum Balb/c murine and in adult Balb/c murine. [Results] ICC were located mainly between the circular and longitudinal muscle layers (called ICC-MY) and between the internal thin layer and the thick outer layer of the circular muscle(called ICC-DMP) in the small intestine. The distribution of ICC-MY was continuous. Electron microscope showed that ICC had two or more very long main processes and contained abundant mitochondria, while intermediate filaments were rarely seen. The slow waves of small intestine were proximal cosinal waves in the adult Balb/c murine and the frequency was (17.78±1.52) cycles/min and the amplitude was (0.16±0.02) mV. The slow waves in the 10-days postpartum Balb/c murine resembled those in adult murine and the frequency was (14.00±0.98) cycles/min and the amplitude was (0.09±0.02) mV (P<0.01 vs the adult murine). [Conclusion] Two types of ICC including ICC-MY and ICC-DMP are observed in the young Balb/c murine small intestine which are bipolar or multipolar cells.ICC-MY interconnects with a network. ICC that are undeveloped fully has immature slow waves.%目的 观察未成年Balb/c小鼠小肠Cajal间质细胞(ICC)的形态及分布,并测定其慢波活动情况,以进一步认识ICC的发育.方法 首先,通过免疫组织化学方法观察10天大小Balb/c小鼠小肠ICC的分布及形态特征,采用电镜观察ICC的超微结构;再分别测定10d大小Balb/c小鼠及成年Balb/c小鼠小

  7. Magnetic resonance imaging of the small bowel

    Energy Technology Data Exchange (ETDEWEB)

    Deeab, Dhafer A., E-mail: dhafer_ahmed@yahoo.co [Department of Radiology, St Mary' s Campus, Imperial College NHS Trust, London (United Kingdom); Dick, Elizabeth; Sergot, Antoni A.; Sundblon, Lauren; Gedroyc, Wady [Department of Radiology, St Mary' s Campus, Imperial College NHS Trust, London (United Kingdom)

    2011-02-15

    Magnetic Resonance Imaging of the Small Bowel (MR Enterography, or MRE) is becoming increasingly popular as the first imaging modality for the diagnosis and follow-up of small bowel diseases. The inherent advantages of MRI, including excellent soft tissue contrast, multiplanar capability and lack of ionising radiation are well known. In addition, the use of luminal contrast agents in MRE has the added advantage of demonstrating the lumen and the wall directly, something not possible to achieve with conventional small bowel barium follow-through imaging. This review will highlight recent technical advances to this low cost, simple technique which is easily achievable in all hospitals. It will also review normal and abnormal radiological findings and highlight the value of this technique to both the clinician and patient alike in the investigation of small bowel disease.

  8. Serotonin, visceral sensation in irritable bowel syndrome

    Institute of Scientific and Technical Information of China (English)

    QIAN Jia-ming

    2007-01-01

    @@ Irritable bowel syndrome(IBS) is highly prevalent and can affect up to 20% of the population.1 It is a common gastrointestinal(GI) disorder associated with alterations in motility,secretion and visceral sensation.

  9. Diverticulosis of the small bowel with Diverticulitis

    Energy Technology Data Exchange (ETDEWEB)

    Barner, L.; Doldt, H.; Strecker, E.P.

    1980-11-01

    Case report of diverticulosis of the small bowel complicated by diverticulitis. Radiography is the method of choice to demonstrate this finding preoperatively. This entity should be included in the differential diagnosis of right lower quadrant abdominal pecin.

  10. Definition and Facts for Irritable Bowel Syndrome

    Science.gov (United States)

    ... Causes Diagnosis Treatment Eating, Diet, & Nutrition Clinical Trials Definition & Facts for Irritable Bowel Syndrome What is IBS? ... physical and mental causes and isn’t a product of a person’s imagination. What are the four ...

  11. Use of thiopurines in inflammatory bowel disease

    DEFF Research Database (Denmark)

    Frei, Pascal; Biedermann, Luc; Nielsen, Ole Haagen;

    2013-01-01

    The use of thiopurines as immunosuppression for the treatment of refractory or chronic active inflammatory bowel disease is established for both Crohn's disease and ulcerative colitis. Nevertheless, many questions remain concerning the optimal treatment regimens of azathioprine, 6-mercaptopurine...

  12. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Guenaga, Katia K F G; Matos, Delcio; Wille-Jørgensen, Peer

    2009-01-01

    BACKGROUND: The presence of bowel contents during surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only. OBJECTIVES: To dete......BACKGROUND: The presence of bowel contents during surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only. OBJECTIVES...... with no MBP. Primary outcomes included anastomosis leakage - both rectal and colonic - and combined figures. Secondary outcomes included mortality, peritonitis, reoperation, wound infection, extra-abdominal complications, and overall surgical site infections. DATA COLLECTION AND ANALYSIS: Data were...

  13. Bowel endometriosis: Recent insights and unsolved problems

    OpenAIRE

    2011-01-01

    Bowel endometriosis affects between 3.8% and 37% of women with endometriosis. The evaluation of symptoms and clinical examination are inadequate for an accurate diagnosis of intestinal endometriosis. Transvaginal ultrasonography is the first line investigation in patients with suspected bowel endometriosis and allows accurate determination of the presence of the disease. Radiological techniques (such as magnetic resonance imaging and multidetector computerized tomography enteroclysis) are use...

  14. Modern treatment of short bowel syndrome

    DEFF Research Database (Denmark)

    Jeppesen, Palle B

    2013-01-01

    Recently, the US Food and Drug Administration and the European Medicines Agency approved the glucagon-like peptide 2 analogue, teduglutide, for the treatment of short bowel syndrome (SBS), and this review describes the physiological basis for its clinical use.......Recently, the US Food and Drug Administration and the European Medicines Agency approved the glucagon-like peptide 2 analogue, teduglutide, for the treatment of short bowel syndrome (SBS), and this review describes the physiological basis for its clinical use....

  15. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Güenaga, Katia F; Matos, Delcio; Wille-Jørgensen, Peer

    2011-01-01

    The presence of bowel contents during colorectal surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only.An enema before...... the rectal surgery to clean the rectum and facilitate the manipulation for the mechanical anastomosis is used for many surgeons. This is analysed separately...

  16. Use of Prebiotics for Inflammatory Bowel Disease

    OpenAIRE

    Andrew Szilagyi

    2005-01-01

    The relevance of diet in both the pathogenesis and the therapy of inflammatory bowel disease is an evolving science. Disturbance of intestinal microflora (dysbiosis) is putatively a key element in the environmental component causing inflammatory bowel disease. Prebiotics are among the dietary components used in an attempt to counteract dysbiosis. Such predominantly carbohydrate dietary components exert effects on the luminal environment by physicochemical changes through pH alteration, by pro...

  17. Cutaneous manifestations of inflammatory bowel disease

    Directory of Open Access Journals (Sweden)

    Al Roujayee Abdulaziz

    2007-01-01

    Full Text Available Inflammatory bowel disease (IBD has many extraintestinal manifestations, and skin lesions are one of the most frequently described extraintestinal findings. Reports indicate an incidence of cutaneous manifestations ranging from 2 to 34%, Cutaneous manifestations are usually related to the activity of the bowel disease but may have an independent course. In this review we aim to address the various cutaneous manifestations associated with IBD, their impact on the disease course, and the treatment options available.

  18. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Güenaga, Katia F; Matos, Delcio; Wille-Jørgensen, Peer

    2011-01-01

    The presence of bowel contents during colorectal surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only.An enema before the r...... the rectal surgery to clean the rectum and facilitate the manipulation for the mechanical anastomosis is used for many surgeons. This is analysed separately...

  19. Hypomagnesemia in short bowel syndrome patients

    Directory of Open Access Journals (Sweden)

    Simone Chaves Miranda

    2000-11-01

    Full Text Available CONTEXT: Magnesium support to small bowel resection patients. OBJECTIVE: Incidence and treatment of hypomagnesemia in patients with extensive small bowel resection. DESIGN: Retrospective study. SETTING: Metabolic Unit of the University Hospital Medical School of Ribeirão Preto, University of São Paulo, Brazil. PATIENTS: Fifteen patients with extensive small bowel resection who developed short bowel syndrome. MAIN MEASUREMENTS: Serum magnesium control of patients with bowel resection. Replacement of magnesium when low values were found. RESULTS: Initial serum magnesium values were obtained 21 to 180 days after surgery. Hypomagnesemia [serum magnesium below 1.5 mEq/l (SD 0.43] was detected in 40% of the patients [1,19 mEq/l (SD 0.22]. During the follow-up period, 66% of the patients presented at least two values below reference (1.50 mEq/l. 40% increased their serum values after magnesium therapy. CONCLUSION: Metabolic control of serum magnesium should be followed up after extensive small bowel resection. Hypomagnesemia may be found and should be controlled.

  20. Perovskite photovoltaics: Slow recombination unveiled

    Science.gov (United States)

    Moser, Jacques-E.

    2017-01-01

    One of the most salient features of hybrid lead halide perovskites is the extended lifetime of their photogenerated charge carriers. This property has now been shown experimentally to originate from a slow, thermally activated recombination process.

  1. Birth control - slow release methods

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007555.htm Birth control - slow release methods To use the sharing features on this page, please enable JavaScript. Certain birth control methods contain man-made forms of hormones. These ...

  2. Slow light in flight imaging

    CERN Document Server

    Wilson, Kali; Gariepy, Genevieve; Henderson, Robert; Howell, John; Faccio, Daniele

    2016-01-01

    Slow-light media are of interest in the context of quantum computing and enhanced measurement of quantum effects, with particular emphasis on using slow-light with single photons. We use light-in-flight imaging with a single photon avalanche diode camera-array to image in situ pulse propagation through a slow light medium consisting of heated rubidium vapour. Light-in-flight imaging of slow light propagation enables direct visualisation of a series of physical effects including simultaneous observation of spatial pulse compression and temporal pulse dispersion. Additionally, the single-photon nature of the camera allows for observation of the group velocity of single photons with measured single-photon fractional delays greater than 1 over 1 cm of propagation.

  3. Nonlinear evolution of whistler wave modulational instability

    DEFF Research Database (Denmark)

    Karpman, V.I.; Lynov, Jens-Peter; Michelsen, Poul;

    1995-01-01

    The nonlinear evolution of the modulational instability of whistler waves coupled to fast magnetosonic waves (FMS) and to slow magnetosonic waves (SMS) is investigated. Results from direct numerical solutions in two spatial dimensions agree with simplified results from a set of ordinary different......The nonlinear evolution of the modulational instability of whistler waves coupled to fast magnetosonic waves (FMS) and to slow magnetosonic waves (SMS) is investigated. Results from direct numerical solutions in two spatial dimensions agree with simplified results from a set of ordinary...

  4. SEVERE SHORT-BOWEL SYNDROME AFTER TOTAL SMALL BOWEL RESECTION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Extensive intestine resection may result in short bowel syndrome (SBS) which is difficult to manage. This study reports a rare SBS case in a 6-year-old boy following resection of total jujunoileum and right colon. Our experience in 4-years follow-up and literature reports on SBS is discussed. The purpose of this study was also to evaluate the nutritional absorptive capacity and intestinal adaptation. In the 15th postoperative month, barium x-ray study showed a significantly extended and enlarged duodenum and colon. The intestinal transit time was prolonged to 22 hours. The absorption rate of palmic acid, glycine and D-xylose had increased from 57%, 50% and 4% respectively in the 15th postoperative month, to 75%, 65% and 6% in the 2nd postoperative year. His absorptive capacity allowed him normal oral feeding and normal school life. Our data confirmed the reports of the colon as an energy-salvage organ, and suggested that it may have some capacity to absorb long-chain fatty acids and amino acids.

  5. Moderate Cortical Cooling Eliminates Thalamocortical Silent States during Slow Oscillation.

    Science.gov (United States)

    Sheroziya, Maxim; Timofeev, Igor

    2015-09-23

    Reduction in temperature depolarizes neurons by a partial closure of potassium channels but decreases the vesicle release probability within synapses. Compared with cooling, neuromodulators produce qualitatively similar effects on intrinsic neuronal properties and synapses in the cortex. We used this similarity of neuronal action in ketamine-xylazine-anesthetized mice and non-anesthetized mice to manipulate the thalamocortical activity. We recorded cortical electroencephalogram/local field potential (LFP) activity and intracellular activities from the somatosensory thalamus in control conditions, during cortical cooling and on rewarming. In the deeply anesthetized mice, moderate cortical cooling was characterized by reversible disruption of the thalamocortical slow-wave pattern rhythmicity and the appearance of fast LFP spikes, with frequencies ranging from 6 to 9 Hz. These LFP spikes were correlated with the rhythmic IPSP activities recorded within the thalamic ventral posterior medial neurons and with depolarizing events in the posterior nucleus neurons. Similar cooling of the cortex during light anesthesia rapidly and reversibly eliminated thalamocortical silent states and evoked thalamocortical persistent activity; conversely, mild heating increased thalamocortical slow-wave rhythmicity. In the non-anesthetized head-restrained mice, cooling also prevented the generation of thalamocortical silent states. We conclude that moderate cortical cooling might be used to manipulate slow-wave network activity and induce neuromodulator-independent transition to activated states. Significance statement: In this study, we demonstrate that moderate local cortical cooling of lightly anesthetized or naturally sleeping mice disrupts thalamocortical slow oscillation and induces the activated local field potential pattern. Mild heating has the opposite effect; it increases the rhythmicity of thalamocortical slow oscillation. Our results demonstrate that slow oscillation can be

  6. Traveling wave tube and method of manufacture

    Science.gov (United States)

    Vancil, Bernard K. (Inventor)

    2004-01-01

    A traveling wave tube includes a glass or other insulating envelope having a plurality of substantially parallel glass rods supported therewithin which in turn support an electron gun, a collector and an intermediate slow wave structure. The slow wave structure itself provides electrostatic focussing of a central electron beam thereby eliminating the need for focussing magnetics and materially decreasing the cost of construction as well as enabling miniaturization. The slow wave structure advantageously includes cavities along the electron beam through which the r.f. energy is propagated, or a double, interleaved ring loop structure supported by dielectric fins within a ground plane cylinder disposed coaxially within the glass envelope.

  7. Optical signal processing using slow and fast light technologies

    DEFF Research Database (Denmark)

    Capmany, J.; Sales, Salvador; Xue, Weiqi;

    2009-01-01

    microwave or millimeter-wave frequency bands, we present one scheme to increase the achievable RF phase shift by enhancing light slow-down or speed-up. As a real application in microwave photonics, a widely tunable microwave photonic notch filter with 100% fractional tuning range is also proposed......We review the theory of slow and fat light effects due to coherent population oscillations in semiconductor waveguides, which can be potentially applied in microwave photonic systems as a RF phase shifters. In order to satisfy the application requirement of 360 degrees RF phase shift at different...

  8. Entangled photons from on-chip slow light

    CERN Document Server

    Takesue, Hiroki; Kuramochi, Eiichi; Notomi, Masaya

    2014-01-01

    We report the first entanglement generation experiment using an on-chip slow light device. With highly efficient spontaneous four-wave mixing enhanced by the slow light effect in a coupled resonator optical waveguide based on a silicon photonic crystal, we generated 1.5-$\\mu$m-band high-dimensional time-bin entangled photon pairs. We undertook two-photon interference experiments and observed the coincidence fringes with visibilities $>74\\%$. The present result enables us to realize an on-chip entanglement source with a very small footprint, which is an essential function for quantum information processing based on integrated quantum photonics.

  9. A case of enterolith small bowel obstruction and jejunal diverticulosis

    Institute of Scientific and Technical Information of China (English)

    Buhussan Hayee; Hamed Noor Khan; Talib Al-Mishlab; John F Mcpartlin

    2003-01-01

    We reported a case of 79-year old woman with known large bowel diverticulosis presenting with small bowel obstruction due to stone impaction - found on plain abdominal X-ray.Contrast studies demonstrated small bowel diverticulosis.At laparotomy, the gall bladder was normal with no stones and no abnormal communication with small bowel - excluding the possibility of a gallstone ileus. Analysis of the stone revealed a composition of bile pigments and calcium oxalate.This was a rare case of small bowel obstruction due to enterolith formation - made distinctive by calcification (previously unreported in the proximal small bowel).

  10. Contrast enema depiction of small-bowel volvulus in complicated neonatal bowel obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Oscar M.; Daneman, Alan; Miller, Stephen F. [Hospital for Sick Children, Department of Diagnostic Imaging, Toronto, ON (Canada)

    2004-12-01

    About one-half of patients with meconium ileus (MI) present with a complication such as volvulus, atresia, meconium peritonitis or giant cystic meconium peritonitis. The treatment of these complications requires surgery. However, the preoperative diagnosis of complicated MI is difficult. We describe two neonates with complicated small-bowel obstruction, one with MI related to cystic fibrosis and the other not related to cystic fibrosis. In both, contrast enema depicted a spiral appearance of the distal small bowel, which at surgery proved to be the result of volvulus associated with antenatal bowel perforation. This appearance of the small bowel on contrast enema in this clinical setting has not been previously described. The recognition of this spiral appearance of the distal small bowel suggests the need for surgery. (orig.)

  11. The Potential of/for 'Slow': Slow Tourists and Slow Destinations

    Directory of Open Access Journals (Sweden)

    J. Guiver

    2016-05-01

    Full Text Available Slow tourism practices are nothing new; in fact, they were once the norm and still are for millions of people whose annual holiday is spent camping, staying in caravans, rented accommodation, with friends and relations or perhaps in a second home, who immerse themselves in their holiday environment, eat local food, drink local wine and walk or cycle around the area. So why a special edition about slow tourism? Like many aspects of life once considered normal (such as organic farming or free-range eggs, the emergence of new practices has highlighted differences and prompted a re-evaluation of once accepted practices and values. In this way, the concept of ‘slow tourism’ has recently appeared as a type of tourism that contrasts with many contemporary mainstream tourism practices. It has also been associated with similar trends already ‘branded’ slow: slow food and cittaslow (slow towns and concepts such as mindfulness, savouring and well-being.

  12. Light and sound - emerging imaging techniques for inflammatory bowel disease

    Science.gov (United States)

    Knieling, Ferdinand; Waldner, Maximilian J

    2016-01-01

    Patients with inflammatory bowel disease are known to have a high demand of recurrent evaluation for therapy and disease activity. Further, the risk of developing cancer during the disease progression is increasing from year to year. New, mostly non-radiant, quick to perform and quantitative methods are challenging, conventional endoscopy with biopsy as gold standard. Especially, new physical imaging approaches utilizing light and sound waves have facilitated the development of advanced functional and molecular modalities. Besides these advantages they hold the promise to predict personalized therapeutic responses and to spare frequent invasive procedures. Within this article we highlight their potential for initial diagnosis, assessment of disease activity and surveillance of cancer development in established techniques and recent advances such as wide-view full-spectrum endoscopy, chromoendoscopy, autofluorescence endoscopy, endocytoscopy, confocal laser endoscopy, multiphoton endoscopy, molecular imaging endoscopy, B-mode and Doppler ultrasound, contrast-enhanced ultrasound, ultrasound molecular imaging, and elastography. PMID:27433080

  13. The genetic background of inflammatory bowel disease.

    Science.gov (United States)

    Yang, H; Rotter, J I

    2000-01-01

    Available evidence indicates that genetic factors are essential in providing the susceptibility to the majority of the various forms of inflammatory bowel disease occurring in man. It is also clear that the genetic susceptibility to these diseases is complex, and that more than one gene may predispose (the concept of multilocus/oligogenic inheritance), and likely in different etiologic combinations (the concept of genetic heterogeneity). Paradigms are now available that should lead to the identification of a number of these predisposing genes. These paradigms include the candidate gene approach, systematic genome wide scans, and mouse human synteny. While genome wide scans are currently limited to multiplex family linkage studies, both candidate genes and mouse human synteny can be approached in either linkage or association paradigms. Eventually whole genome association studies will be available as well. Identification of inflammatory bowel disease predisposing genes should lead to their incorporation in studies of natural history, investigation of environmental risk factors, and especially utilization of genetic markers in clinical trials. This will allow us to identify the best therapy available for the individual patient based on their unique genetic constitution. With advances in molecular technology, the search for genes influencing traits and diseases with a complex genetic background, such as the inflammatory bowel diseases, has become a realistic task. Although exogenous or infectious agents may contribute to the pathogenesis or may trigger the onset of disease, and the immune system almost certainly mediates the tissue damage, it is clear from available data that genetic factors determine the susceptibility of a given individual to inflammatory bowel disease (reviewed below). Thus, genetic studies are essential for the delineation of the basic etiologies of the various forms of inflammatory bowel disease and thus can aid in the development of radically

  14. Heterotaxy syndromes and abnormal bowel rotation

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Beverley [Stanford University, Lucile Packard Children' s Hospital, Department of Radiology, Stanford, CA (United States); Koppolu, Raji; Sylvester, Karl [Lucile Packard Children' s Hospital at Stanford, Department of Surgery, Stanford, CA (United States); Murphy, Daniel [Lucile Packard Children' s Hospital at Stanford, Department of Cardiology, Stanford, CA (United States)

    2014-05-15

    Bowel rotation abnormalities in heterotaxy are common. As more children survive cardiac surgery, the management of gastrointestinal abnormalities has become controversial. To evaluate imaging of malrotation in heterotaxy with surgical correlation and provide an algorithm for management. Imaging reports of heterotaxic children with upper gastrointestinal (UGI) and/or small bowel follow-through (SBFT) were reviewed. Subsequently, fluoroscopic images were re-reviewed in conjunction with CT/MR studies. The original reports and re-reviewed images were compared and correlated with surgical findings. Nineteen of 34 children with heterotaxy underwent UGI, 13/19 also had SBFT. In 15/19 reports, bowel rotation was called abnormal: 11 malrotation, 4 non-rotation, no cases of volvulus. Re-review, including CT (10/19) and MR (2/19), designated 17/19 (90%) as abnormal, 10 malrotation (abnormal bowel arrangement, narrow or uncertain length of mesentery) and 7 non-rotation (small bowel and colon on opposite sides plus low cecum with probable broad mesentery). The most useful CT/MR findings were absence of retroperitoneal duodenum in most abnormal cases and location of bowel, especially cecum. Abnormal orientation of mesenteric vessels suggested malrotation but was not universal. Nine children had elective bowel surgery; non-rotation was found in 4/9 and malrotation was found in 5/9, with discrepancies (non-rotation at surgery, malrotation on imaging) with 4 original interpretations and 1 re-review. We recommend routine, early UGI and SBFT studies once other, urgent clinical concerns have been stabilized, with elective laparoscopic surgery in abnormal or equivocal cases. Cross-sectional imaging, usually obtained for other reasons, can contribute diagnostically. Attempting to assess mesenteric width is important in differentiating non-rotation from malrotation and more accurately identifies appropriate surgical candidates. (orig.)

  15. Etiopathogenesis of inflammatory bowel diseases

    Institute of Scientific and Technical Information of China (English)

    Silvio Danese; Claudio Fiocchi

    2006-01-01

    Theories explaining the etiopathogenesis of inflammatory bowel disease (IBD) have been proposed ever since Crohn's disease (CD) and ulcerative colitis (UC) were recognized as the two major forms of the disease. Although the exact cause(s) and mechanisms of tissue damage in CD and UC have yet to be completely understood, enough progress has occurred to accept the following hypothesis as valid: IBD is an inappropriate immune response that occurs in genetically susceptible individuals as the result of a complex interaction among environmental factors, microbial factors, and the intestinal immune system. Among an almost endless list of environmental factors, smoking has been identified as a risk factor for CD and a protective factor for UC. Among microbial factors, no convincing evidence indicates that classical infectious agents cause IBD, while mounting evidence points to an abnormal immune response against the normal enteric flora as being of central importance. Gut inflammation is mediated by cells of the innate as well as adaptive immune systems, with the additional contribution of non-immune cells, such as epithelial, mesenchymal and endothelial cells, and platelets.

  16. Selenium and inflammatory bowel disease.

    Science.gov (United States)

    Kudva, Avinash K; Shay, Ashley E; Prabhu, K Sandeep

    2015-07-15

    Dietary intake of the micronutrient selenium is essential for normal immune functions. Selenium is cotranslationally incorporated as the 21st amino acid, selenocysteine, into selenoproteins that function to modulate pathways involved in inflammation. Epidemiological studies have suggested an inverse association between selenium levels and inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis that can potentially progress to colon cancer. However, the underlying mechanisms are not well understood. Here we summarize the current literature on the pathophysiology of IBD, which is multifactorial in origin with unknown etiology. We have focused on a few selenoproteins that mediate gastrointestinal inflammation and activate the host immune response, wherein macrophages play a pivotal role. Changes in cellular oxidative state coupled with altered expression of selenoproteins in macrophages drive the switch from a proinflammatory phenotype to an anti-inflammatory phenotype to efficiently resolve inflammation in the gut and restore epithelial barrier integrity. Such a phenotypic plasticity is accompanied by changes in cytokines, chemokines, and bioactive metabolites, including eicosanoids that not only mitigate inflammation but also partake in restoring gut homeostasis through diverse pathways involving differential regulation of transcription factors such as nuclear factor-κB and peroxisome proliferator-activated receptor-γ. The role of the intestinal microbiome in modulating inflammation and aiding in selenium-dependent resolution of gut injury is highlighted to provide novel insights into the beneficial effects of selenium in IBD.

  17. [Parasitosis and irritable bowel syndrome].

    Science.gov (United States)

    Ibarra, Catalina; Herrera, Valentina; Pérez de Arce, Edith; Gil, Luis Carlos; Madrid, Ana María; Valenzuela, Lucía; Beltrán, Caroll J

    2016-06-01

    Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract characterised by multi-factorial aetiology. In IBS physiopathology are involved diverse factors between them biological, psychosocial, and environmental components which affect the immune activation status of gut mucosa. Among these factors is recognized the intestinal parasitosis. Post-infection IBS (PI-IBS) is recognised as a subgroup of functional disorders whose symptoms onset appear after a symptomatic intestinal infection caused by microbial agents. There are few studies regarding of relationship between IBS and intestinal parasitosis in Chile. However, is has been well described a positive association between IBS and Blastocystis hominis infections, one of prevalent parasites in Chile. In other countries, is also described a relationship between IBS and amebiasis and giardiasis. Both, characterized by a common mode of transmission through water as well as contaminated food. Because the high prevalence of parasitosis in our country it is necessary to expand the association studies to clarify the strength of the parasites ethiology in IBS.

  18. Inflammatory bowel disease in pregnancy

    Institute of Scientific and Technical Information of China (English)

    Dawn B Beaulieu; Sunanda Kane

    2011-01-01

    Crohn's disease and ulcerative colitis affect women in their child-bearing years. Family planning has come to be a common discussion between the gastroenterologist and the inflammatory bowel disease (IBD) patient.Disease control prior to desired conception and throughout pregnancy is the most important thing to keep in mind when caring for the IBD patient. Continued medical management during pregnancy is crucial in optimizing outcomes. Studies indicate that quiescent disease prior to conception infer the best pregnancy outcomes, similar to those in the general population.Active disease prior to and during pregnancy, can lead to complications such as pre-term labor, low birth weight, and small for gestational age infants. Although there are no definitive long term effects of pregnancy on IBD, there are some limited studies that suggest that it may alter the disease course. Understanding the literature and its limitations is important in the modern era of IBD care. Educating the patient and taking a team approach with the obstetrician will help achieve successful outcomes for mother and baby.

  19. Pharmacogenetics in inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Marie Pierik; Paul Rutgeerts; Robert Vlietinck; Severine Vermeire

    2006-01-01

    Pharmacogenetics is the study of the association between variability in drug response and (or) drug toxicity and polymorphisms in genes. The goal of this field of science is to adapt drugs to a patient's specific genetic background and therefore make them more efficacious and safe. In this article we describe the variants in genes that influence either the efficacy or toxicity of common drugs used in the treatment of inflammatory bowel diseases (IBD), ulcerative colitis (UC),and Crohn's disease (CD) including sulfasalazine and mesalazine, azathioprine (AZA) and 6-mercaptopurine (6-MP), methotrexate (MTX), glucocorticosteroids (CSs) and infliximab. Furthermore, difficulties with pharmacogenetic studies in general and more specifically in IBD are described. Although pharmacogenetics is a promising field that already contributed to a better understanding of some of the underlying mechanisms of action of drugs used in IBD, the only discovery translated until now into daily practice is the relation between thiopurine S-methyltransferase (TPMT) gene polymorphisms and hematological toxicity of thiopurine treatment. In the future it is necessary to organize studies in well characterized patient cohorts who have been uniformly treated and systematically evaluated in order to quantitate drug response more objectively. An effort should be made to collect genomic DNA from all patients enrolled in clinical drug trials after appropriate informed consent for pharmacogenetic studies.

  20. Theory of carrier depletion and light amplification in active slow light photonic crystal waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2013-01-01

    Using a perturbative approach, we perform a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguide. The impact of slow-light propagation on the carrier-depletion-induced nonlinear gain saturation...... of the device is investigated. An effective rate-equation-based model is presented. It is shown that it well accounts for the three-dimensional simulation results. Simulations indicate that a slow-light-enhanced photonic crystal traveling-wave amplifier has a high small-signal modal gain and low saturation...

  1. MHD waves in sunspots

    CERN Document Server

    Sych, Robert

    2015-01-01

    The review addresses the spatial frequency morphology of sources of sunspot oscillations and waves, including their localization, size, oscillation periods, height localization with the mechanism of cut-off frequency that forms the observed emission variability. Dynamic of sunspot wave processes, provides the information about the structure of wave fronts and their time variations, investigates the oscillation frequency transformation depending on the wave energy is shown. The initializing solar flares caused by trigger agents like magnetoacoustic waves, accelerated particle beams, and shocks are discussed. Special attention is paid to the relation between the flare reconnection periodic initialization and the dynamics of sunspot slow magnetoacoustic waves. A short review of theoretical models of sunspot oscillations is provided.

  2. Dose from slow negative muons.

    Science.gov (United States)

    Siiskonen, T

    2008-01-01

    Conversion coefficients from fluence to ambient dose equivalent, from fluence to maximum dose equivalent and quality factors for slow negative muons are examined in detail. Negative muons, when stopped, produce energetic photons, electrons and a variety of high-LET particles. Contribution from each particle type to the dose equivalent is calculated. The results show that for the high-LET particles the details of energy spectra and decay yields are important for accurate dose estimates. For slow negative muons the ambient dose equivalent does not always yield a conservative estimate for the protection quantities. Especially, the skin equivalent dose is strongly underestimated if the radiation-weighting factor of unity for slow muons is used. Comparisons to earlier studies are presented.

  3. Diffusion theory of slow responses

    Institute of Scientific and Technical Information of China (English)

    李景德; 陈敏; 郑凤; 周镇宏

    1997-01-01

    When an action is applied to a macroscopic substance, there is a particular sort of slow response he sides the well-known fast response. Using diffusion theory, the characteristics of slow response in dielectric, elastic, piezoelectric, and pyroelectric relaxation may he explained A time domain spectroscopy method suitable for slow and fast responses in linear and nonlinear effects is given. Every relaxation mechanism contributes a peak in differential spectroscopy, and its position, height, and line shape show the dynamical properties of the mechanism The method of frequency domain spectroscopy is suitable only for linear fast response. Time domain spectroscopy is another nonequiv-alent powerful method. The theory is confirmed by a lot of experimental data

  4. [Chronic inflammatory bowel diseases and nutrition].

    Science.gov (United States)

    Meier, R

    1996-01-01

    The etiology of inflammatory bowel disease is still unknown. Several potential mechanisms are discussed. The etiological and therapeutic importance of nutrition is controversial. Though changes in dietary habits and incidence of inflammatory bowel disease during the last century were in parallel, no specific nutritional factor has been isolated. No dietary prophylaxis of inflammatory bowel disease is yet known; all dietary therapies in inflammatory bowel disease aim to improve nutritional support and to diminish inflammation by bowel rest. Children and adolescents gain in weight and height. Total parenteral nutrition will not substantially reduce disease activity and operation rates. Total parenteral nutrition can only be recommended in ulcerative colitis patients with severe disease in the initial phase and in Crohn's patients with severe malnutrition and intestinal complications. Enteral nutrition support is less effective in ulcerative colitis than in Crohn's disease. Reported remission rates on enteral nutrition are 25% for ulcerative colitis and up to 80% for Crohn. However, in active Crohn's disease enteral nutrition is less effective than standard therapy with methylprednisolone and sulfasalizine. It is generally believed that nutrition therapy in combination with drugs is the best treatment modality. There is no evidence to support the importance of any combination of the formula diets such as elemental, oligopeptide, or polymeric formulations. Administration of formula diets by nasogastric tubes all show similar remission rates. Whether newer diets supplemented with arginine, glutamine, omega-3-fatty acids or short chain fatty acids increase remission rates is not known. Further studies in this field are warranted.

  5. Fast Deflagration Waves.

    Science.gov (United States)

    1980-07-01

    Fendell (1970) to finite Mach numbers, and uncovered the existence of very slow deflagration waves. JI.. -2- 2. The governing equations The governing...FlapmSI,$ Cambridge University Press. 2. Buckmaster, J. 1976. The quenching of deflagration vaves. Combust. Flme. 26, 151-162. 3. Bush, W.B. & Fendell , F.E

  6. Slow light with electromagnetically induced transparency in cylindrical waveguide

    CERN Document Server

    Hatta, Agus Muhamad; Al-Hagan, Ola A; Moiseev, Sergey A

    2014-01-01

    Slow light with electromagnetically induced transparency (EIT) in the core of cylindrical waveguide (CW) for an optical fiber system containing three-level atoms is investigated. The CW modes are treated in the weakly guiding approximation which renders the analysis into manageable form. The transparency window and permittivity profile of the waveguide due to the strong pump field in the EIT scheme is calculated. For a specific permittivity profile of the waveguide due to EIT, the propagation constant of the weak signal field and spatial shape of fundamental guided mode are calculated by solving the vector wave equation using the finite difference method. It is found that the transparency window and slow light field can be controlled via the CW parameters. The reduced group velocity of slow light in this configuration is useful for many technological applications such as optical memories, effective control of single photon fields, optical buffer and delay line.

  7. Genetics of Inflammatory Bowel Diseases.

    Science.gov (United States)

    McGovern, Dermot P B; Kugathasan, Subra; Cho, Judy H

    2015-10-01

    In this review, we provide an update on genome-wide association studies (GWAS) in inflammatory bowel disease (IBD). In addition, we summarize progress in defining the functional consequences of associated alleles for coding and noncoding genetic variation. In the small minority of loci where major association signals correspond to nonsynonymous variation, we summarize studies defining their functional effects and implications for therapeutic targeting. Importantly, the large majority of GWAS-associated loci involve noncoding variation, many of which modulate levels of gene expression. Recent expression quantitative trait loci (eQTL) studies have established that the expression of most human genes is regulated by noncoding genetic variations. Significant advances in defining the epigenetic landscape have demonstrated that IBD GWAS signals are highly enriched within cell-specific active enhancer marks. Studies in European ancestry populations have dominated the landscape of IBD genetics studies, but increasingly, studies in Asian and African-American populations are being reported. Common variation accounts for only a modest fraction of the predicted heritability and the role of rare genetic variation of higher effects (ie, odds ratios markedly deviating from 1) is increasingly being identified through sequencing efforts. These sequencing studies have been particularly productive in more severe very early onset cases. A major challenge in IBD genetics will be harnessing the vast array of genetic discovery for clinical utility through emerging precision medical initiatives. In this article, we discuss the rapidly evolving area of direct-to-consumer genetic testing and the current utility of clinical exome sequencing, especially in very early onset, severe IBD cases. We summarize recent progress in the pharmacogenetics of IBD with respect to partitioning patient responses to anti-TNF and thiopurine therapies. Highly collaborative studies across research centers and

  8. [Migraine and irritable bowel syndrome].

    Science.gov (United States)

    Mulak, Agata; Paradowski, Leszek

    2005-01-01

    The association between migraine and functional gastrointestinal disorders has been confirmed by many clinical observations and epidemiological studies. In most patients during the attacks of migraine, apart from various neurological and vascular symptoms, gastrointestinal disturbances occur including nausea, vomiting, abdominal pain or diarrhea. Functional gastrointestinal disorders, such as irritable bowel syndrome (IBS), are reported in migraine patients in periods between the attacks as well. On the other hand 23-53% of IBS patients have frequent headaches. Migraine and IBS often coexist with fibromyalgia and other chronic pain syndromes and functional disorders. Migraine and IBS affect approximately 10-20% of the general population, usually young adults. Both diseases are more prevalent in women, perhaps due to the role of estrogen in their pathogenesis. Looking for the common pathogenetic mechanisms of IBS and migraine the role of the brain-gut axis, neuroimmune and neuroendocrine interactions are being considered. The influence of stress on symptom occurrence and severity seems to be associated with hyperactivity of the hypothalamic-pituitary-adrenal axis. The enteric nervous system as a source of numerous neurotransmitters and visceral reflexes is a plausible common pathogenic link between IBS and migraine. In particular serotonin being the main neurotransmitter of the gastrointestinal tract plays a relevant role in the pathogenesis of IBS as well as migraine. Nowadays, agonists and antagonists of serotoninergic receptors are the most efficacious drugs for IBS and migraine therapy. Some side effects of triptans, 5-HT(1B/D) agonists, used in migraine treatment may be connected with the influence of triptans on the gastrointestinal functions. A better understanding of the relationship between migraine and IBS may result in more effective treatment of both diseases.

  9. Arteriovenous Malformation Detected by Small Bowel Endoscopy

    Directory of Open Access Journals (Sweden)

    Takaaki Fujii

    2014-10-01

    Full Text Available Gastrointestinal bleeding that originates in the small intestine is often difficult to diagnose. When successful diagnosis reveals a lesion that can be localized preoperatively, the laparoscopic approach is an appropriate and beneficial treatment modality for small bowel resection. A 69-year-old man presented with a 6-month history of gastrointestinal bleeding and symptomatic transfusion-dependent anemia. Upper and lower endoscopy were normal. Double-balloon endoscopy established the source of the bleeding as a 0.5-cm polypoid mass appearing as a submucosal tumor with redness and pulsation in the lower ileum, suggesting a vascular lesion. Laparoscopic small bowel resection was successful in removing the mass in the ileum. Histological evaluation of the mass revealed an arteriovenous malformation. Preoperative small bowel endoscopy can be useful for diagnosing the cause and localization of arteriovenous malformation in the small intestine.

  10. Small Bowel Obstruction due to Intestinal Xanthomatosis

    Directory of Open Access Journals (Sweden)

    L. E. Barrera-Herrera

    2015-01-01

    Full Text Available Vast majority of bowel obstruction is due to postoperative adhesions, malignancy, intestinal inflammatory disease, and hernias; however, knowledge of other uncommon causes is critical to establish a prompt treatment and decrease mortality. Xanthomatosis is produced by accumulation of cholesterol-rich foamy macrophages. Intestinal xanthomatosis is an uncommon nonneoplastic lesion that may cause small bowel obstruction and several cases have been reported in the English literature as obstruction in the jejunum. We report a case of small intestinal xanthomatosis occurring in a 51-year-old female who presented with one day of copious vomiting and intermittent abdominal pain. Radiologic images revealed jejunal loop thickening and inflammatory changes suggestive of foreign body obstruction, diagnostic laparoscopy found two strictures at the jejunum, and a pathologic examination confirmed a segmental small bowel xanthomatosis. This case illustrates that obstruction even without predisposing factors such as hyperlipidemia or lymphoproliferative disorders.

  11. Irritable bowel syndrome: focus on otilonium bromide.

    Science.gov (United States)

    Boeckxstaens, Guy; Clavé, Pere; Corazziari, Enrico S; Tack, Jan

    2014-02-01

    Irritable bowel syndrome is a prevalent and chronic disorder, characterized by recurrent abdominal pain/discomfort, bloating and altered bowel habits. This condition affects an estimated 10-15% of the population worldwide and impacts heavily on a patient's daily life and ability to work, as well as healthcare resource utilization. Drug therapy aimed at correcting the primary symptoms of diarrhea/constipation/bloating may have little effect on abdominal pain, which results from visceral hypersensitivity. Smooth muscle relaxants or antispasmodics decrease the tone and contractility of intestinal smooth muscle, effectively managing abdominal pain. Otilonium bromide has been widely used worldwide and has been found to be safe and well tolerated, and superior to placebo for the reduction of symptoms and the prevention of symptom relapse in patients with irritable bowel syndrome.

  12. Confocal Laser Endomicroscopy in Inflammatory Bowel Disease

    DEFF Research Database (Denmark)

    Rasmussen, Ditlev Nytoft; Karstensen, John Gásdal; Riis, Lene Buhl

    2015-01-01

    of confocal laser endomicroscopy for inflammatory bowel disease. METHODS: Available literature was searched systematically for studies applying confocal laser endomicroscopy in Crohn's disease or ulcerative colitis. Relevant literature was reviewed and only studies reporting original clinical data were...... included. Next, eligible studies were analysed with respect to several parameters, such as technique and clinical aim and definitions of outcomes. RESULTS: Confocal laser endomicroscopy has been used for a wide range of purposes in inflammatory bowel disease, covering assessment of inflammatory severity...... of histological features such as colonic crypts, epithelial gaps and epithelial leakiness to fluorescein. CONCLUSIONS: Confocal laser endomicroscopy remains an experimental but emerging tool for assessment of inflammatory bowel disease. It is the only method that enables in vivo functional assessment...

  13. Multidetector CT Findings of Bowel Transection in Blunt Abdominal Trauma

    NARCIS (Netherlands)

    Cho, H.S.; Woo, J.Y.; Hong, H.S.; Park, M.H.; Ha, H.I.; Yang, I.; Lee, Y.; Jung, A.Y.; Hwang, J.Y.

    2013-01-01

    OBJECTIVE: Though a number of CT findings of bowel and mesenteric injuries in blunt abdominal trauma are described in literature, no studies on the specific CT signs of a transected bowel have been published. In the present study we describe the incidence and new CT signs of bowel transection in blu

  14. Outcomes of Bowel Resection in Patients with Crohn's Disease.

    Science.gov (United States)

    Moghadamyeghaneh, Zhobin; Carmichael, Joseph C; Mills, Steven D; Pigazzi, Alessio; Stamos, Michael J

    2015-10-01

    There is limited data regarding outcomes of bowel resection in patients with Crohn's disease. We sought to investigate complications of such patients after bowel resection. The Nationwide Inpatient Sample databases were used to examine the clinical data of Crohn's patients who underwent bowel resection during 2002 to 2012. Multivariate regression analysis was performed to investigate outcomes of such patients. We sampled a total of 443,950 patients admitted with the diagnosis of Crohn's disease. Of these, 20.5 per cent had bowel resection. Among patients who had bowel resection, 51 per cent had small bowel Crohn's disease, 19.4 per cent had large bowel Crohn's disease, and 29.6 per cent had both large and small bowel Crohn's disease. Patients with large bowel disease had higher mortality risk compared with small bowel disease [1.8% vs 1%, adjusted odds ratio (AOR): 2.42, P Crohn's disease (AOR: 1.90, P Crohn's disease, 20.5 per cent underwent bowel resection during 2002 to 2012. Although colonic disease has a higher mortality risk, small bowel disease has a higher risk of postoperative fistula.

  15. Magnetoacoustic Waves in the Solar Stratified Atmosphere

    Institute of Scientific and Technical Information of China (English)

    郑惠南; 王水; 吴式灿; 李波

    2001-01-01

    The propagation of magnetoacoustic waves in the solar atmosphere consisting of the photosphere, chromosphere and corona has been studied numerically by time-dependent multi-dimensional magnetohydrodynamic (MHD) simulation. Pressure disturbances are introduced at the bottom of the chromosphere and at the bottom of the corona, respectively. The computational results show that incurred fast and slow MHD waves propagate away from the source of the disturbances. The fast MHD wave propagates as an expansive wave in the radial direction, while the slow one steepens and it may evolve into a slow shock. We suggest that the extreme ultraviolet imaging telescope wave observed by the SOHO and Moreton wave are a fast MHD wave propagating in the corona and in the chromosphere, respectively.

  16. Periodic solutions and slow manifolds

    NARCIS (Netherlands)

    Verhulst, F.

    2006-01-01

    After reviewing a number of results from geometric singular perturbation theory, we give an example of a theorem for periodic solutions in a slow manifold. This is illustrated by examples involving the van der Pol-equation and a modified logistic equation. Regarding nonhyperbolic transitions we disc

  17. Dirac-graphene quasiparticles in strong slow-light pulse

    Science.gov (United States)

    Golovinski, P. A.; Astapenko, V. A.; Yakovets, A. V.

    2017-02-01

    An analytical Volkov's solution of the massless Dirac equation for graphene in the field of slow-light pulse with arbitrary time dependence is obtained. Exact solutions are presented for special cases of monochromatic field and a single-cycle pulse. Following the Fock-Schwinger proper time method, the Green's function for quasiparticles is derived with the account of the influence an external classical electromagnetic wave field.

  18. [Neurological complications of inflammatory bowel diseases].

    Science.gov (United States)

    Cieplik, N; Stangel, M; Bachmann, O

    2013-02-01

    Inflammatory bowel diseases, such as Crohn's disease, ulcerative colitis, autoantibody driven celiac disease and infectious Whipple's disease can all be associated with neurological symptoms. The neurological manifestation may occur even before the gastrointestinal symptoms or the enteropathic symptoms can even be absent as in celiac disease. These diseases can be caused by malresorption and lack of vitamins due to enteral inflammation as well as (auto-)immunological mechanisms and drug-associated side effects. Thus, inflammatory bowel diseases have to be considered in the differential diagnosis. In this review the most common neurological manifestations of these diseases will be described as well as the diagnostic approach.

  19. Teaching transanal irrigation for functional bowel disorders.

    Science.gov (United States)

    Coggrave, Maureen; Norton, Christine

    Transanal irrigation of the bowel in the management of functional bowel disorders is currently receiving increased attention following the recent introduction of the Peristeen irrigation kit (Coloplast Ltd) in April 2007. Irrigation provides a welcome additional choice in the limited range of available interventions for the management of these patients. However, evidence to support clinical practice around irrigation is limited and nursing knowledge and experience of irrigation is only just developing. This paper reports a series of master classes conducted to support and develop the use of irrigation in the UK, and demonstrates the value of the master class as an educational tool when introducing a novel therapy.

  20. Case report: Congenital short bowel syndrome

    Directory of Open Access Journals (Sweden)

    Palle Lalitha

    2010-01-01

    Full Text Available Congenital short bowel syndrome (SBS is a relatively rare condition as compared to acquired SBS. It is associated with significant mortality and morbidity. Infants usually present with failure to thrive, recurrent vomiting, and diarrhea. It is important to suspect and diagnose this condition promptly, as early initiation of parenteral nutrition or surgery, if necessary, may result in a favorable outcome. We discuss a case of an infant aged 26 days, who presented with failure to thrive, recurrent vomiting, and weight loss. A contrast study of the gastrointestinal tract revealed a short small bowel, with malrotation. The infant was started on parenteral nutrition, but succumbed shortly thereafter to severe disseminated sepsis.

  1. Short bowel syndrome: epidemiology and etiology.

    Science.gov (United States)

    Wales, Paul W; Christison-Lagay, Emily R

    2010-02-01

    Pediatric short bowel syndrome (SBS) is most commonly caused by congenital or acquired conditions of the newborn. SBS is associated with an inability of the bowel to adequately absorb water and nutrients in sufficient quantities to meet caloric, fluid, and electrolyte demands, thus necessitating dependence on parenteral nutrition (PN). It is this dependence on PN, that is responsible for the majority of morbidity and mortality associated with SBS, including central venous catheter infections and PN-induced cholestatic liver dysfunction. There are very few estimates of SBS incidence and mortality in the literature. The epidemiology of SBS is reviewed and the limitations of the published literature are discussed.

  2. Use of Prebiotics for Inflammatory Bowel Disease

    Directory of Open Access Journals (Sweden)

    Andrew Szilagyi

    2005-01-01

    Full Text Available The relevance of diet in both the pathogenesis and the therapy of inflammatory bowel disease is an evolving science. Disturbance of intestinal microflora (dysbiosis is putatively a key element in the environmental component causing inflammatory bowel disease. Prebiotics are among the dietary components used in an attempt to counteract dysbiosis. Such predominantly carbohydrate dietary components exert effects on the luminal environment by physicochemical changes through pH alteration, by production of short chain fatty acids and by selectively promoting putatively 'health-beneficial' bacteria. The present review elaborates on some of the background rationale and mechanisms on the use of prebiotics. Additionally, published animal and human trials are discussed.

  3. Embolisation of Posttraumatic Superior Mesenteric Artery Pseudoaneurysm in a Patient with Short Bowel Syndrome Preceding Bowel Transplantation

    Directory of Open Access Journals (Sweden)

    Vinko Vidjak

    2011-01-01

    Full Text Available Penetrating abdominal trauma often causes bowel injuries which may lead to “short bowel syndrome” which is a potential indication for bowel transplantation. Posttraumatic pseudoaneurysms of abdominal arteries are often a result of penetrating abdominal trauma. We report a successful embolisation of posttraumatic superior mesenteric artery (SMA branch pseudoaneurysm using microcoil, in a patient with short bowel syndrome who was successfully transplanted three months after embolisation.

  4. Beam interactions with surface waves and higher-order modes in oversized backward wave oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Ogura, Kazuo; Kojima, Akihiko; Kawabe, Fumiaki; Yambe, Kiyoyuki [Niigata University, Niigata (Japan); Amin, Ruhul [Islamic University of Technology, Gazipur (Bangladesh)

    2014-10-15

    Beam interactions with surface waves and higher-order modes in an oversized backward wave oscillator (BWO) are studied. In addition to the well-known Cherenkov interaction, the slow cyclotron interaction occurs due to transverse perturbations of the electron beam. The Cherenkov interaction dominates the slow cyclotron interaction. Growth rates of both the interactions for the higher order modes are small compared with those for the surface-wave modes in an oversized BWO. The coaxial slow-wave structure exhibits a reduced number of higher-order modes, which consequently reduces the mode competition problem and improves beam interactions with higher order modes. For higher values of beam currents, the slow cyclotron wave grows at a faster rate than the Cherenkov waves.

  5. Interneuron-mediated inhibition synchronizes neuronal activity during slow oscillation

    Science.gov (United States)

    Chen, Jen-Yung; Chauvette, Sylvain; Skorheim, Steven; Timofeev, Igor; Bazhenov, Maxim

    2012-01-01

    The signature of slow-wave sleep in the electroencephalogram (EEG) is large-amplitude fluctuation of the field potential, which reflects synchronous alternation of activity and silence across cortical neurons. While initiation of the active cortical states during sleep slow oscillation has been intensively studied, the biological mechanisms which drive the network transition from an active state to silence remain poorly understood. In the current study, using a combination of in vivo electrophysiology and thalamocortical network simulation, we explored the impact of intrinsic and synaptic inhibition on state transition during sleep slow oscillation. We found that in normal physiological conditions, synaptic inhibition controls the duration and the synchrony of active state termination. The decline of interneuron-mediated inhibition led to asynchronous downward transition across the cortical network and broke the regular slow oscillation pattern. Furthermore, in both in vivo experiment and computational modelling, we revealed that when the level of synaptic inhibition was reduced significantly, it led to a recovery of synchronized oscillations in the form of seizure-like bursting activity. In this condition, the fast active state termination was mediated by intrinsic hyperpolarizing conductances. Our study highlights the significance of both intrinsic and synaptic inhibition in manipulating sleep slow rhythms. PMID:22641778

  6. CT enteroclysis in small bowel Crohn's disease

    Energy Technology Data Exchange (ETDEWEB)

    Kohli, Marc D. [Department of Radiology, Indiana University School of Medicine, Indianapolis, IN (United States); Maglinte, Dean D.T. [Department of Radiology, Indiana University School of Medicine, Indianapolis, IN (United States)], E-mail: dmaglint@iupui.edu

    2009-03-15

    The diagnostic evaluation of small bowel Crohn's disease has changed dramatically over the last decade. The introduction of wireless capsule endoscopy, double balloon endoscopy and the introduction of newer therapeutic agents have changed the role of imaging in the small bowel. Additionally, advances in multidetector CT technology have further changed how radiologic investigations are utilized in the diagnosis and management of small bowel Crohn's disease. This article describes how we perform CT enteroclysis in the investigation of small bowel Crohn's disease and discusses the role of CT enteroclysis in the current management of small bowel Crohn's disease.

  7. Microbiota biodiversity in inflammatory bowel disease

    Science.gov (United States)

    2014-01-01

    Gut microbiota plays a significant role in human health and energy balance, and provides protection against disease states. An altered balance between microbiota and its host (dysbiosis) would appear to contribute to the development of Inflammatory Bowel Disease (IBD), Crohn’s Disease (CD) and Ulcerative Colitis (UC). CD and UC are chronic inflammatory diseases of the gastrointestinal tes. PMID:24684926

  8. Opioid-Induced Constipation and Bowel Dysfunction

    DEFF Research Database (Denmark)

    Müller-Lissner, Stefan; Bassotti, Gabrio; Coffin, Benoit

    2016-01-01

    OBJECTIVE:  To formulate timely evidence-based guidelines for the management of opioid-induced bowel dysfunction. SETTING:  Constipation is a major untoward effect of opioids. Increasing prescription of opioids has correlated to increased incidence of opioid-induced constipation. However, the inh...

  9. Managing irritable bowel syndrome in primary care.

    Science.gov (United States)

    Corsetti, Maura; Whorwell, Peter J

    2015-06-01

    The classic symptoms of irritable bowel syndrome (IBS) are abdominal pain, bloating and some form of bowel dysfunction. The pain is typically colicky in nature and can occur at any site although most commonly it is on the left side. The abdomen feels flat in the morning and then gradually becomes more bloated as the day progresses reaching a peak by late afternoon or evening. It then subsides again over night. Traditionally IBS is divided into diarrhoea, constipation or alternating subtypes. IBS patients frequently complain of one or more non-colonic symptoms, these include constant lethargy, low backache, nausea, bladder symptoms suggestive of an irritable bladder, chest pain and dyspareunia in women. The traditional view that IBS is a largely psychological condition is no longer tenable. Rectal bleeding, a family history of malignancy and a short history in IBS should always be treated with suspicion. Both pain and bowel dysfunction are often made worse by eating. It is recommended that a coeliac screening test is undertaken to rule out this condition. Other routine tests should include inflammatory markers such as CRP or ESR. Calprotectin is a marker for leukocytes in the stools and detects gastrointestinal inflammation. A negative test almost certainly rules out inflammatory bowel disease, especially in conjunction with a normal CRP. Fermentable carbohydrates can have a detrimental effect on IBS and this has led to the introduction of the low FODMAP diet.

  10. Review article : inflammatory bowel disease and genetics

    NARCIS (Netherlands)

    Weersma, R. K.; Van Dullemen, H. M.; Van der Steege, G.; Nolte, I. M.; Kleibeuker, J. H.; Dijkstra, G.

    2007-01-01

    Introduction Inflammatory bowel disease (IBD) comprising ulcerative colitis (UC) and Crohn's disease (CD) is multigenic disorder. Tremendous progress has been achieved in unravelling the genetic background of IBD. It has led to the discovery of mutations in NOD2 associated with ileal CD and numerous

  11. Genetic epidemiology of irritable bowel syndrome.

    Science.gov (United States)

    Makker, Jasbir; Chilimuri, Sridhar; Bella, Jonathan N

    2015-10-28

    Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder characterized by presence of abdominal pain or discomfort associated with altered bowel habits. It has three main subtypes - constipation predominant IBS (C-IBS), diarrhea predominant IBS (D-IBS) and IBS with mixed features of both diarrhea as well as constipation (M-IBS). Its pathophysiology and underlying mechanisms remain elusive. It is traditionally believed that IBS is a result of multiple factors including hypersensitivity of the bowel, altered bowel motility, inflammation and stress. Initial studies have shown familial aggregation of IBS suggesting shared genetic or environmental factors. Twin studies of IBS from different parts of world have shown higher concordance rates among monozygotic twins than dizygotic twins, and thus suggesting a genetic component to this disorder. Multiple studies have tried to link single-nucleotide polymorphisms (SNPs) to IBS but there is little evidence that these SNPs are functional. Various molecules have been studied and investigated by the researchers. Serotonin, a known neurotransmitter and a local hormone in the enteric nervous system, has been most extensively explored. At this time, the underlying gene pathways, genes and functional variants linked with IBS remain unknown and the promise of genetically-determined risk prediction and personalize medicine remain unfulfilled. However, molecular biological technologies continue to evolve rapidly and genetic investigations offer much promise in the intervention, treatment and prevention of IBS.

  12. New pharmaceuticals in inflammatory bowel disease.

    Science.gov (United States)

    Łodyga, Michał; Eder, Piotr; Bartnik, Witold; Gonciarz, Maciej; Kłopocka, Maria; Linke, Krzysztof; Małecka-Panas, Ewa; Radwan, Piotr; Rydzewska, Grażyna

    2015-01-01

    This paper complements the previously published Guidelines of the Working Group of the Polish Society of Gastroenterology and former National Consultant in Gastroenterology regarding the management of patients with Crohn's disease and ulcerative colitis. Attention was focused on the new pharmaceutical recently registered for inflammatory bowel disease treatment.

  13. Nuclear medicine imaging of inflammatory bowel disease

    Energy Technology Data Exchange (ETDEWEB)

    Froelich, J.W.

    1987-01-01

    With the availability of indium-labeled white blood cells, radionuclide imaging studies have a definite role in the diagnosis and staging of patients with inflammatory bowel disease. The In-/sup 111/ white blood cell study is particularly helpful in evaluating recurrent disease in patients with severe intercurrent diseases and in screening patients without the need for barium examinations.

  14. Inflammatory Bowel Disease: School Nurse Management

    Science.gov (United States)

    Kitto, Lisa

    2010-01-01

    Initial symptoms and diagnosis of inflammatory bowel disease (IBD) usually occur between 10 and 20 years of age, although younger cases are reported. The complicated nature of IBD diagnosis and treatment can interfere with physical and emotional development that normally occurs in school-age children and adolescents. The school nurse should be…

  15. Inflammatory Bowel Disease. Medical and psychological aspects

    NARCIS (Netherlands)

    Albersnagel, Frans; Dijkstra, Gerard

    2007-01-01

    A review is presented in which the state of the art of behavioural-scientific research on inflammatory bowel disease (BID) is sorted out. After a short introduction on medical aspects of the two diseases that constitute IBD, i.e. Crohn's disease and ulcerative colitis, the factors that may have an i

  16. Management of inflammatory bowel disease in pregnancy

    NARCIS (Netherlands)

    S. Vermeire (Silvio); F. Carbonnel (Franck); P.G. Coulie (Pierre); V. Geenen (Vincent); J.M.W. Hazes (Mieke); P.L. Masson (Pierre); F. de Keyser (Filip); E. Louis (Edouard)

    2012-01-01

    textabstractBackground and Aims: Inflammatory bowel disease (IBD) is a chronic disease affecting mainly young people in their reproductive years. IBD therefore has a major impact on patients' family planning decisions. Management of IBD in pregnancy requires a challenging balance between optimal dis

  17. Neuropeptide receptor expression in inflammatory bowel disease

    NARCIS (Netherlands)

    Beek, Willy Pascale ter

    2008-01-01

    Inflammatory bowel disease (IBD), i.e. Crohn’s disease and ulcerative colitis are characterized by a chronic inflammation of the gastrointestinal tract. Neuropeptides are involved in the regulation of intestinal motility, chloride secretion and inflammatory response, three processes that are disturb

  18. Inflammatory bowel disease: potential therapeutic strategies

    DEFF Research Database (Denmark)

    Nielsen, O H; Vainer, B; Bregenholt, S;

    1997-01-01

    This review deals with potential and possibly primary therapeutics that, through insight into the inflammatory cascade, result in more rational treatment principles replacing the classical therapy of inflammatory bowel disease (IBD), i.e. Crohn's disease (CD) and ulcerative colitis (UC). These ne...

  19. Current treatment for inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Chang-tai Xu; Xiue-gan Guo; Bo-rong Pan

    2003-01-01

    @@Introduction Idiopathic inflammatory bowel disease consists of Crohn's disease (CD) and ulcerative colitis (UC). CD can affect any part of the gastrointestinal tract, from the mouth to the anus, and is also known as regional enteritis, terminal ileitis, or granulomatous……

  20. Acupuncture treatment in irritable bowel syndrome

    NARCIS (Netherlands)

    Schneider, A; Enck, P; Streitberger, K; Weiland, C; Bagheri, S; Witte, S; Friederich, HC; Zipfel, S; Herzog, W.

    2006-01-01

    Background and aims: Despite occasional positive reports on the efficacy of acupuncture (AC) on functions of the gastrointestinal tract, there is no conclusive evidence that AC is effective in the treatment of irritable bowel syndrome (IBS). Patients and methods: Forty three patients with IBS accord

  1. Environmental factors in inflammatory bowel disease

    DEFF Research Database (Denmark)

    Hansen, Tanja Stenbaek; Jess, Tine; Vind, Ida;

    2011-01-01

    The role of environmental factors in development of inflammatory bowel disease (IBD) remains uncertain. The aim of the present study was to assess a number of formerly suggested environmental factors in a case-control study of an unselected and recently diagnosed group of patients with IBD...

  2. Cold and Slow Molecular Beam

    CERN Document Server

    Lu, Hsin-I; Wright, Matthew J; Patterson, Dave; Doyle, John M

    2011-01-01

    Employing a two-stage cryogenic buffer gas cell, we produce a cold, hydrodynamically extracted beam of calcium monohydride molecules with a near effusive velocity distribution. Beam dynamics, thermalization and slowing are studied using laser spectroscopy. The key to this hybrid, effusive-like beam source is a "slowing cell" placed immediately after a hydrodynamic, cryogenic source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH beams are created in two regimes. One modestly boosted beam has a forward velocity of vf = 65 m/s, a narrow velocity spread, and a flux of 10^9 molecules per pulse. The other has the slowest forward velocity of vf = 40 m/s, a longitudinal temperature of 3.6 K, and a flux of 5x10^8 molecules per pulse.

  3. Research Development and Perspective on Slow Slip, Tremors, and Slow Earthquakes

    Institute of Scientific and Technical Information of China (English)

    Wang Yanzhao; Shen Zhengkang

    2007-01-01

    Seismological and geodetic observations indicate that slow slip sometimes occurs in active fault zones beneath the seismogenic depth, and large slow slip can result in transient ground motion.Slow earthquakes, on the other hand, emit tremor-like signals within a narrow frequency band, and usually produce no catastrophic consequences. In general, slow slip and slow earthquakes probably correspond to deformation processes associated with releasing elastic energy in fault zones, and understanding their mechanisms may help improve our understanding of fault zone dynamic processes. This article reviews the research progress on slow slip and slow earthquakes over the last decade. Crustal motion and tremor activities associated with slow slip and slow earthquakes have been investigated extensively, mainly involving locating sources of slow slip and slow earthquakes and numerical modeling of their processes. In the meantime, debates have continued about slow slip and slow earthquakes,such as their origins, relationship, and mechanisms.

  4. STUDY OF LARGE BOWEL OBSTRUCTION IN ADULTS

    Directory of Open Access Journals (Sweden)

    Atish

    2013-05-01

    Full Text Available ABSTRACT: AIM : To study the Incidence, Etiology, Clinical featur es, Investigations undertaken to arrive at Diagnosis, Treatment and Post-operative o utcomes of large bowel obstruction in adults. METHODS : This is a prospective observational study of larg e bowel obstruction in adults and was carried out from Nov 2010 to Oct 2012. RESULTS : A total of 211 cases of intestinal obstruction were diagnosed out of these 25(11.85% cases were o f large bowel obstruction. Maximum patients 8(32% cases belonged to age group 51-60yrs and 15( 60% cases were males. Obstipation seen in 25(100%, pain 22(88%, distension 21(84%, tendern ess 22(88% and increased bowel sounds 21(84%. X-ray and ultrasonography was useful in 21 (84% cases while CT scan was used in only 7 cases and proved 100% effective.13(52% cases were of sigmoid volvulus, 1(4% of caecal volvulus and 9(36% cases of malignancy.15(60% cases underw ent primary resection anastomosis and 10(40% cases had a decompressive colostomy.8(32% patients developed immediate wound complication, 3(12% cases had anastomotic leak, 1( 4% case developed burst abdomen and 6(24% cases had septicaemia. Mortality of the stud y was 6(24% cases. CONCLUSION : Patients with large bowel obstruction in adults form a small percentage of patients. Commonest causes are sigmoid volvulus and obstructing colorectal maligna ncies. X-ray abdomen, Ultrasound of abdomen and Computerized Tomography of abdomen are very hel pful in diagnosing. Single stage resectional procedure without colostomies can be done in patien ts even in emergency surgeries and Proximal diverting colostomies may be safely performed in pa tients with pre-existing sepsis, shock, gangrene of large bowel and excessively loaded colon with re versal of colostomies and a definitive procedure may be performed later, after stabilisation of pati ents. Post-operative complications are more because of late presentation associated with comorb idities and large bacterial load of

  5. [Irritable Bowel Syndrome treatment: a multidisciplinary approach].

    Science.gov (United States)

    Shani-Zur, Dana; Wolkomir, Keren

    2015-01-01

    Irritable Bowel Syndrome affects 9-23% of the general population. This diagnosis contributes to more frequent doctor visits and multiple consultations by patients. The current approach to treating IBS is symptomatic and consists of a regimen of first line pharmacological treatment options; the use of anti-depressant drugs is also common. The efficiency of complementary medicine in the treatment of IBS has been studied in the last few years. Qualitative multidisciplinary approach studies, using personalized medicines with complementary therapies are needed. We present the case of a 39-year-old woman with a diagnosis of IBS since 2009, who complained about gastrointestinal symptoms since the age of 13 and severe episodes of spasmodic stomach aches in the last year self-ranked as 10, on a 0-10 scale; 3-4 episodes a month, which last for 5 days, accompanied by severe flatulence and bloating. In addition, she has constipation (one bowel movement every 10 days), alternating with multiple diarrheic bowel movements (6 times a day). Using a multidisciplinary approach, including medicinal care, Chinese medicine, reflexology and naturopathy resulted in significant improvement in symptoms and quality of life, as well as gradual reduction of drugs, approved by her physician. Stomach ache self-ranked now as 1, on a 0-10 scale; and flatulence and bloating self-ranked as mild. Bowel movement frequency increased and is now every other day. She no longer has diarrheic and/or multiple bowel movements. This case report emphasizes the importance of integrative treatment in IBS and its benefit in improving patients' quality of life.

  6. Inflammatory bowel disease in pediatric patients

    Energy Technology Data Exchange (ETDEWEB)

    Charron, M. [Children`s Hospital of Pittsburgh, Pittsburgh (United States). Dept. of Radiology

    1997-12-01

    Optimal management of chronic idiopathic inflammatory bowel disease requires determination of disease localization and intensity. Scintigraphy with the use of {sup 99m}Tc - HMPAO- White Bloods Cells ({sup 99m}Tc - HMPAO-WBC) is a relatively new noninvasive nuclear medicine procedure. They have evaluated more than 230 children and have found a high correspondence between the disease distribution shown by the {sup 99m}Tc - HMPAO- WBC scan and that shown by endoscopic, radiologic, or surgical methods. Additionally the {sup 99m}Tc - HMPAO-WBC scan has the ability of identifying extra intestinal site of inflammation, such as appendicitis and others. The {sup 99m}Tc - HMPAO-WBC scan is reliable in differentiating Crohn`s disease from ulcerative colitis. Some patients because of unequivocal demonstrable small bowel uptake are reclassified from ulcerative colitis to Crohn`s disease. The medication regimen is frequently altered because of the intensity of uptake displayed by the {sup 99m}Tc - HMPAO-WBC scan. It is a practical and safe study even in an acutely ill patient who may not tolerate endoscopic or radiological study. At their institution, the {sup 99m}Tc - HMPAO-WBC scan is now part of the initial evaluation, and follow-up of patients with inflammatory bowel disease. In conclusion the {sup 99m}Tc - HMPAO-WBC is excellent for the detection, localization and characterization of inflammatory bowel disease in children. Compared with the other methods of investigation this study requires no bowel preparation, is noninvasive and has excellent diagnostic accuracy.

  7. Direct Comparison of a Solar Moreton Wave, EUV Wave and CME (Preprint)

    Science.gov (United States)

    2013-10-30

    Veronig et al. 2010) show that other traveling EIT disturbances definitely are freely propagating MHD waves.” The latest studies from STEREO and SDO...one was reported). From an analytic model of the Moreton wave on 2005 January 17, Temmer et al. (2009) concluded that the wave was driven either...propagating EUV disturbances were identified as fast–mode magnetohydrodynamic ( MHD ) waves. They also identified a slow bright wave behind the fast

  8. PREVALENCE AND FACTORS AFFECTING REM AND SLOW WAVE SLEEP REBOUND ON CPAP TITRATION STUDY IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA Prevalencia de los factores que afectan el sueño REM y el brote de ondas lentas en los estudios con CPAP en apnea obstructiva del sueño

    Directory of Open Access Journals (Sweden)

    Edgar Osuna S

    2008-03-01

    Full Text Available Background. In patients with obstructive sleep apnea syndrome (OSAS treatment with CPAP results in an increase of REM sleep and slow wave sleep, but there is limited information about the prevalence of REM rebound in patients with OSAS and possible factors related to the rebound. Objective. REM rebound (RR and slow wave sleep rebound (SWSR has been described as a frequent phenomenon that occurs during CPAP titration, but the quantity that qualify for RR has not been mentioned in literature. The objective of our study was to determine the prevalence of REM rebound and slow wave sleep rebound in our sleep disorders center, to attempt to define RR and look for factors that may affect RR and SWSR on the first night of CPAP titration. Materials and methods. We included patients who had both baseline polysomnogram (bPSG and CPAP polysomnogram (cPSG studies done in the same laboratory. We included 179 patients>18 years with Apnea hypopnea index (AHI>10/hr on the baseline study, with an adequate CPAP titration study. We compared the percentages of REM sleep and slow wave sleep during bPSG and cPSG. We analyzed the frequency of presentation and looked for the factors affecting RR and SWSR. Results. 179 patients were enrolled (M/F:118/61, with a mean age of 48.6±4 for men, and 51.6±12.9 for women. The mean interval between the bPSG and cPSG was 45 days. The mean REM percentage during the bPSG was 15.55 percent and during cPSG study it was 21.57 percent. We took 6 percent as our differential point as the results became statistically significant at this point (p:0001. We therefore present our data by dividing our patients population with RR6%. The mean SWS percentage during the bPSG was 8.11±9.68 and during the cPSG was 13.17±10, with a p:0.35 which is not statistically significant. The multiple regression model showed that the variables that contribute more to the REM change are: REM sleep during bPSG (-0.56, bAHI (0.24 and the body mass index (0

  9. Traveling-Wave Tubes

    Science.gov (United States)

    Kory, Carol L.

    1998-01-01

    The traveling-wave tube (TWT) is a vacuum device invented in the early 1940's used for amplification at microwave frequencies. Amplification is attained by surrendering kinetic energy from an electron beam to a radio frequency (RF) electromagnetic wave. The demand for vacuum devices has been decreased largely by the advent of solid-state devices. However, although solid state devices have replaced vacuum devices in many areas, there are still many applications such as radar, electronic countermeasures and satellite communications, that require operating characteristics such as high power (Watts to Megawatts), high frequency (below 1 GHz to over 100 GHz) and large bandwidth that only vacuum devices can provide. Vacuum devices are also deemed irreplaceable in the music industry where musicians treasure their tube-based amplifiers claiming that the solid-state and digital counterparts could never provide the same "warmth" (3). The term traveling-wave tube includes both fast-wave and slow-wave devices. This article will concentrate on slow-wave devices as the vast majority of TWTs in operation fall into this category.

  10. Inherited ataxia with slow saccades

    Directory of Open Access Journals (Sweden)

    R T Chakor

    2012-01-01

    Full Text Available Ataxia is a symptom of cerebellar dysfunction. Slowly progressive ataxia, dysarthria in an adult with a positive family history suggests an inherited cerebellar ataxia. We present an adult with gradually progressive ataxia and slow saccades. There was history of similar illness in his son. Genetic testing for spinocerebellar ataxia 2 was positive. We discuss the various inherited ataxias, causes of acute, progressive ataxia syndromes, episodic ataxias and ataxia associated with other neurological signs like peripheral neuropathy, pyramidal features, movement disorders and cognitive decline.

  11. Can Occupational Therapy Slow Alzheimer's Decline?

    Science.gov (United States)

    ... news/fullstory_162135.html Can Occupational Therapy Slow Alzheimer's Decline? Patients, caregivers may reap some benefits, but ... slow down the physical decline that comes with Alzheimer's disease, a new clinical trial suggests. The study ...

  12. Kinematic dynamo induced by helical waves

    OpenAIRE

    Wei, Xing

    2014-01-01

    We investigate numerically the kinematic dynamo induced by the superposition of two helical waves in a periodic box as a simplified model to understand the dynamo action in astronomical bodies. The effects of magnetic Reynolds number, wavenumber and wave frequency on the dynamo action are studied. It is found that this helical-wave dynamo is a slow dynamo. There exists an optimal wavenumber for the dynamo growth rate. A lower wave frequency facilitates the dynamo action and the oscillations o...

  13. Integrated Photonics Enabled by Slow Light

    DEFF Research Database (Denmark)

    Mørk, Jesper; Chen, Yuntian; Ek, Sara;

    2012-01-01

    In this talk we will discuss the physics of slow light in semiconductor materials and in particular the possibilities offered for integrated photonics. This includes ultra-compact slow light enabled optical amplifiers, lasers and pulse sources.......In this talk we will discuss the physics of slow light in semiconductor materials and in particular the possibilities offered for integrated photonics. This includes ultra-compact slow light enabled optical amplifiers, lasers and pulse sources....

  14. Clinical peculiarities of antibiotic associated bowels impairment and its significance in irritable bowel syndrome appearance

    Directory of Open Access Journals (Sweden)

    І. O. Pasichna

    2016-06-01

    Full Text Available Aim: the main objective of this study was to investigate bowels impairment due to treatment with antibiotics, its incidence and clinical peculiarities; to evaluate its role in appearance of in irritable bowel syndrome. Material and Methods. We studied 110 patients (33 males and 77 females, age range 16-83 years, who received treatment with antibiotic. We evaluated the function of the intestine before treatment with antibiotic, then in 1 week, 3 months after treatment finish (1, 2, 3, 4 visits respectively. Control group included 20 healthy persons, who haven't had antibiotics administered during recent two years. Results. We revealed that the signs of bowel function impairment took place at the first visit in 18.2% of patients, at the second visit – in 60.0% of patients, at the third visit – in 45.5% of patients and at the fourth visit – in 41.1% of patients. At the second, third and fourth visits the signs of bowels function impairment were observed reliably more often then at the first visit (before antibiotic administration, p<0.001. At the second visit the signs bowels function disorders were the most prominent: abdominal pain – in 44.5%, distention – in 46.4%, diarrhea – in 29.1%, constipation – in 18.2%, presence of both (diarrhea and periodically constipation manifestations – in 2.7%; and extraintestinal manifestations (depression. depressed mood, sorrow, apathy, decreased stamina, sleep disturbances – in 29.1% of patients. Clinical manifestations of irritable bowel syndrome occured in 6 months of observation in 32.2% of patients. Conclusions. The signs of bowel function impairment were observed in 60.0% of patients after finishing treatment with antibiotic. This incidence is much higher than in control group (р<0.001. Bowel disorders mostly manifested as the changes in quantity and consistency of feaces, pain, abdominal distention and extraintestinal manifestations. In 32.2% of patients clinical manifestations of

  15. Use of biosimilars in inflammatory bowel disease: Statements of the Italian Group for Inflammatory Bowel Disease.

    Science.gov (United States)

    Annese, Vito; Vecchi, Maurizio

    2014-11-01

    The introduction of biological therapies, particularly anti-TNFα agents, has revolutionized the management of inflammatory bowel disease in those cases which are refractory to conventional treatment; however these drugs are not risk-free and their use has substantially increased the cost of treatment. As marketing protection expires for original, first-generation biopharmaceuticals, lower-cost "copies" of these drugs produced by competitor companies-referred to as biosimilars-are already entering the market. In September 2013, the European Medicines Agency approved two infliximab biosimilars for treatment of adult and paediatric inflammatory bowel disease patients, a decision based largely on efficacy and safety data generated in studies of patients with ankylosing spondylitis and rheumatoid arthritis. For many clinicians, extrapolation practices and the general question of interchangeability between biosimilars and reference biologics are cause for concern. In the present paper, the Italian Group for inflammatory bowel disease presents its statements on these issues, with emphasis on the peculiar clinical characteristics of inflammatory bowel disease and the importance of providing physicians and patients with adequate information and guarantees on the safety and efficacy of these new drugs in the specific setting of inflammatory bowel disease.

  16. Oral distension methods for small bowel MRI: comparison of different agents to optimize bowel distension.

    Science.gov (United States)

    Schmidt, Stefan A; Baumann, Julia A; Stanescu-Siegmund, Nora; Froehlich, Eckhart; Brambs, Hans-Juergen; Juchems, Markus S

    2016-12-01

    Background Different methods for bowel distension prior to magnetic resonance imaging (MRI) examinations were described in recent years. Purpose To compare orally administered psyllium or locust bean gum / mannitol (LBM) with tylose administered through a duodenal catheter for bowel distension in patients undergoing MRI examination of the small bowel. Material and Methods Three different methods of bowel distension prior to MRI were compared: tylose applied through a duodenal catheter and orally administered psyllium and LBM in three groups with 15 patients each. Datasets were blinded and reviewed independently by two experienced radiologists, who assessed the diagnostic value and the maximum luminal diameter. Results Tylose was superior to psyllium and LBM in the examination of the duodenum and proximal jejunum. LBM was superior to the other methods for distension of the ileum and terminal ileum. The greatest luminal diameter of the duodenum was achieved after tylose and distension of the terminal ileum was the best in patients receiving LBM. The psyllium group was inferior to the other two groups in all segments. Conclusion By using LBM as an oral method of bowel distension, many patients can avoid the unpleasant placement of a duodenal catheter without compromising the diagnostic value of the examination.

  17. Slow Monitoring Systems for CUORE

    Science.gov (United States)

    Dutta, Suryabrata; Cuore Collaboration

    2016-09-01

    The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale neutrinoless double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso (LNGS). The experiment is comprised of 988 TeO2 bolometric crystals arranged into 19 towers and operated at a temperature of 10 mK. We have developed slow monitoring systems to monitor the cryostat during detector installation, commissioning, data taking, and other crucial phases of the experiment. Our systems use responsive LabVIEW virtual instruments and video streams of the cryostat. We built a website using the Angular, Bootstrap, and MongoDB frameworks to display this data in real-time. The website can also display archival data and send alarms. I will present how we constructed these slow monitoring systems to be robust, accurate, and secure, while maintaining reliable access for the entire collaboration from any platform in order to ensure efficient communications and fast diagnoses of all CUORE systems.

  18. Slowing Down in Chemical Tristability Systems

    Institute of Scientific and Technical Information of China (English)

    ZHAN,Ye-Hong(詹业宏); ZHANG,Chun-Hua(张春华); WU,Fu-Gen(吴福根); HU,Yi-Hua(胡义华)

    2001-01-01

    In this paper two kinds of slowing down in the chamical tristability systems are studied. One is the critical slowing down at the edges of tristable reion, and the other is the slowing down far from the critical point, which has much to do with the unstable steady-points. The results possess some universal propererties.

  19. [SHORT BOWEL SYNDROME AND NUTRITIONAL ENTERAL].

    Science.gov (United States)

    Ariadel Cobo, Diana; Pereira Cunill, José Luis; Socas Macías, María; Serrano Aguayo, Pilar; Gómez Liébana, Eulalia; Morales Conde, Salvador; García Luna, Pedro Pablo

    2015-12-01

    The particularity of this case is the nutritional management that has managed to avoid the use of prolonged parenteral nutrition and possible complications by placing jejunal tube at the distal end in patients with short bowel. It is a 34-year-old colecistectomizado complicated with postoperative peritonitis and dehiscence; two years he studied with small bowel obstruction, he was made de-volvulus and was complicated with two leak at different times after the second escape took place jejunostomy side double barreled shotgun level dehiscence, presented high debits by afferent loop of the terminal jejunostomy; during admission, polyurethane probe enteral feeding was inserted by the efferent loop jejunostomy. He received jejunal tube feeding laundry in the efferent loop terminal with decreased weight gain and subsequent reconstruction of intestinal transit debit proximal jejunostomy.

  20. Liver Disorders in Inflammatory Bowel Disease

    Directory of Open Access Journals (Sweden)

    Victor Uko

    2012-01-01

    Full Text Available Disorders of the hepatobiliary system are relatively common extraintestinal manifestations of inflammatory bowel disease (IBD. These disorders are sometimes due to a shared pathogenesis with IBD as seen in primary sclerosing cholangitis (PSC and small-duct primary sclerosing cholangitis (small-duct PSC. There are also hepatobiliary manifestations such as cholelithiasis and portal vein thrombosis that occur due to the effects of chronic inflammation and the severity of bowel disease. Lastly, medications used in IBD such as sulfasalazine, thiopurines, and methotrexate can adversely affect the liver. It is important to be cognizant of these disorders as some do have serious long-term consequences. The management of these disorders often requires the expertise of multidisciplinary teams to achieve the best outcomes.

  1. Small bowel obstruction attributable to phytobezoar

    Science.gov (United States)

    Razavianzadeh, Nasrin; Foroutan, Behzad; Honarvar, Farhad; Forozeshfard, Mohammad

    2016-01-01

    Small bowel obstruction (SBO) is a common condition encountered in surgical practice. Literature shows divers and many different etiologies for intestinal obstruction. However, bezoars are rarely reported as an etiological factor. A bezoar happens most commonly in patients with impaired gastrointestinal motility. There are four types of bezoars: phytobezoars, trichobezoars, pharmacobezoars and lactobezoars. The most common type is phytobezoars, which are composed of undigested fiber from vegetables or fruits especially persimmons. They are mostly composed of cellulose, tannin and lignin. The commonest phytobezoar reported worldwide is related to the persimmon fruit ingestion. The most common symptom of bezoar-induced SBO is abdominal pain (96–100%). Other common symptoms include nausea and vomiting. Primary small bowel phytobezoars almost always present as SBO. We present an unusual case of SBO caused by a phytobezoar in a 35-year-old patient. Many types of bezoar can be removed endoscopically, but some will require operative intervention. PMID:28031856

  2. Imaging of inflammatory bowel disease. How?

    Energy Technology Data Exchange (ETDEWEB)

    Hiorns, Melanie P. [Great Ormond Street Hospital for Children, Radiology Department, London (United Kingdom)

    2008-06-15

    Traditionally the small bowel (barium) follow through (SBFT) has been the investigation of choice for that otherwise inaccessible length of gut between the duodenum and the ileocaecal valve. Whilst it is still a widely practised examination by radiologists it is being largely overtaken by other imaging modalities with CT, MRI and capsule endoscopy (CE) all competing for the territory. At the end of the last century, proponents of enteroclysis were predicting the eventual decline of the SBFT (in adults) although at that stage, in a 'state of the art' article, they were still brave enough to say that 'only in the small bowel does barium radiography remain unchallenged'. The same authors now write of how radiological investigations complement other techniques but are no longer the mainstay. (orig.)

  3. NATURAL AGENTS FOR INFLAMMATORY BOWEL DISEASE

    Directory of Open Access Journals (Sweden)

    Darji Vinay Chhanalal

    2011-02-01

    Full Text Available Inflammatory bowel disease (IBD is a chronic inflammatory disease of gastrointestinal tract. It comprises the two conditions, Crohn’s disease and ulcerative colitis, characterized by chronic recurrent ulceration of the bowel. Conventional drugs for colitis treatment include aminosalicylate, corticosteroids,antibiotics & immunomodulators. 5- Amino salicylic acid having side effects in 30% of the patients. Systemic corticosteroids producing incidence of complication is 4.3%. Antibiotic therapy is beneficial in 70% of the patients & Immunomodulators having 50 to 70% beneficial effects. This report shows that there is no any appropriate treatment available to treat IBD without side effects. A natural agent with reduced or no toxicity is therefore essential. In nature there are so many types of natural agents which are used as protective agents in IBD. This article emphasizes many natural products obtained from plant & other sources, which possess potent activity against experimentally induced IBD.

  4. Current medical therapy of inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Kiron M. Das; Sherif A. Farag

    2000-01-01

    The current established drugs used to treat inflammatory bowel disease include glucocorticoids includingnewer agent budesonide, sulfasalazine and 5-ASA compounds such as Asacol, Pentasa, Dipentum andBalsalazide and immunomodulatory agents such as azathioprine, and 6-mercaptopurine. Additional drugswhich have been found to be useful, particularly in refractory cases of Crohn's disease including fistulizingtype of Crohn's disease, include cyclosporine A, methotrexate, humanized antibody against TNFa(cA2),FK506, IL-10, IL-11 and Probiotics. Various agents, whether used alone or in combination, have to betailored for each patient and none is ideal. Exciting new developments directed against proinflammatorypathways, cytokines, free oxygen radicals and cell surface related immune targets are areas of intense recentinvestigations and many novel therapeutic agents are expected to be available in the near future for medicaltreatment of inflammatory bowel disease.

  5. [The pathophysiology of irritable bowel syndrome].

    Science.gov (United States)

    Zouiten, Mekki Lilia; Karoui, Sami; Boubaker, Jalel; Fekih, Monia; Mechmeche, Rachid; Filali, Azza

    2006-05-01

    The irritable bowel syndrome (IBS) is a frequent gastrointestinal disorder (10 -15% of the population). It is characterized by chronic abdominal pain with modification in the bowel habits. The diagnosis is based of ROME II criteria. The pathophysiology of the SII remains unknown . It result from visceral hypersensitivity with anomalies of the digestive motility. These anomalies are secondary of dysfunction of the brain - gut axis modulated by environmental and the psychosocial factors. The understanding of the pathophysiological mechanisms of the SII and in particular the function of the brain-gut axis will permit a better handling of the patients. Indeed, the present knowledge of the neurotransmitter implied in the communication between the central nervous system and the digestive tract are currently the basis of the new therapies aimed to modulate the mechanisms implicated in the causation of the several symptoms of IBS. These novel pharmacotherapy should reduce the indirect societal and costs of IBS.

  6. Anastomotic disruption after large bowel resection

    Institute of Scientific and Technical Information of China (English)

    Mohammad U NasirKhan; Farshad Abir; Walter Longo; Robert Kozol

    2006-01-01

    Anastomotic disruption is a feared and serious complication of colon surgery. Decades of research have identified factors favoring successful healing of anastomoses as well as risk factors for anastomotic disruption. However, some factors, such as the role of mechanical bowel preparation, remain controversial.Despite proper caution and excellent surgical technique,some anastomotic leaks are inevitable. The rapid identification of anastomotic leaks and the timely treatment in these cases are paramount.

  7. The immune response in small bowel transplantation.

    OpenAIRE

    Clark, C. L.

    1996-01-01

    The immunological problems of small bowel transplantation have not yet been overcome. Frequent severe rejection episodes are common in clinical practice, and GVHD may emerge as a significant complication once rejection is more effectively controlled. Both are caused by the large number of lymphocytes in the graft. There is extensive exchange migration of lymphocytes between graft and host even in the absence of rejection, and persisting donor cells in the host may carry the propensity for GVH...

  8. Gas Embolic Stroke Secondary to Bowel Infarction.

    Science.gov (United States)

    Parikh, Dhruv; Leyon, Joe Joseph; Chavda, Swarupsinh

    2016-01-01

    A 69-year-old gentleman with metastatic esophageal adenocarcinoma presented with acute abdominal pain to the emergency medicine department and subsequently developed an acute left hemiplegia while in the resuscitation unit. An unenhanced computed tomography (CT) scan of the head showed right frontal cerebral gas emboli while an unenhanced CT scan of the abdomen and pelvis showed extensive portal venous gas and pneumatosis intestinalis, presumed secondary to bowel infarction.

  9. CT assessment of anastomotic bowel leak

    Energy Technology Data Exchange (ETDEWEB)

    Power, N. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Atri, M. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada)]. E-mail: mostafa.atri@sw.ca; Ryan, S. [Department of Radiology, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Haddad, R. [Department of Surgery, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada); Smith, A. [Department of Surgery, Sunnybrook Hospital, Toronto, Ontario M4N 3M5 (Canada)

    2007-01-15

    Aim: To evaluate the predictors of clinically important gastrointestinal anastomotic leaks using multidetector computed tomography (CT). Subjects and methods: Ninety-nine patients, 73 with clinical suspicion of anastomotic bowel leak and 26 non-bowel surgery controls underwent CT to investigate postoperative sepsis. Fifty patients had undergone large bowel and 23 small bowel anastomoses. The time interval from surgery was 3-30 days (mean 10 {+-} 5.9 SD) for the anastomotic group and 3-40 days (mean 14 {+-} 11 SD) for the control group (p = 0.3). Two radiologists blinded to the final results reviewed the CT examinations in consensus and recorded the presence of peri-anastomotic air, fluid or combination of the two; distant loculated fluid or combination of fluid and air; free air or fluid; and intestinal contrast leak. Final diagnosis of clinically important anastomotic leak (CIAL) was confirmed at surgery or by chart review of predetermined clinical and laboratory criteria. Results: The prevalence of CIAL in the group undergoing CT was 31.5% (23/73). The CT examinations with documented leak were performed 5-28 (mean; 11.4 {+-} 6 SD) days after surgery. Nine patients required repeat operation, 10 percutaneous abscess drainage, two percutaneous drainage followed by surgery, and two prolonged antibiotic treatment and total parenteral nutrition (TPN). Of the CT features examined, only peri-anastomotic loculated fluid containing air was more frequently seen in the CIAL group as opposed to the no leak group (p = 0.04). There was no intestinal contrast leakage in this cohort. Free air was present up to 9 days and loculated air up to 26 days without CIAL. Conclusion: Most postoperative CT features overlap between patients with and without CIAL. The only feature seen statistically more frequently with CIAL is peri-anastomotic loculated fluid containing air.

  10. Irritable bowel syndrome and its psychological management

    Directory of Open Access Journals (Sweden)

    Ravikesh Tripathi

    2015-01-01

    Full Text Available Irritable Bowel Syndrome (IBS is a chronic and disabling gastrointestinal problem that affects psychosocial functioning as well as the quality of life. This case study reports the utility of cognitive behavior therapy as a psychological intervention procedure in a chronic case of IBS. The use of psychological intervention was found to result in a reduction of anxiety; amelioration of the symptoms associated with IBS and improved functioning.

  11. Environmental Risk Factors for Inflammatory Bowel Disease

    OpenAIRE

    Natalie A Molodecky; Gilaad G. Kaplan

    2010-01-01

    Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and is associated with significant morbidity. The etiology of IBD has been extensively studied during the last several decades; however, causative factors in disease pathology are not yet fully understood. IBD is thought to result from the interaction between genetic and environmental factors that influence the normal intestinal commensal flora to trigger an inappropriate mucosal immune res...

  12. Inflammatory bowel disease-associated spondyloarthropathies

    Institute of Scientific and Technical Information of China (English)

    Walter Fries

    2009-01-01

    This issue presents a symposium held in Messina talking about inflammatory bowel disease (IBD) and associated spondyloarthropathies. The topic covers epidemiology and clinical manifestations of IBD-related arthropathies,common genetic and immunologic features, combined therapies for gut and joint inflammation, and future biologic therapies etc. I believe this series of articles will deeply facilitate understanding of and the approach to IBD and associated arthropathies.

  13. The evolving epidemiology of inflammatory bowel disease.

    LENUS (Irish Health Repository)

    Shanahan, Fergus

    2009-07-01

    Epidemiologic studies in inflammatory bowel disease (IBD) include assessments of disease burden and evolving patterns of disease presentation. Although it is hoped that sound epidemiologic studies provide aetiological clues, traditional risk factor-based epidemiology has provided limited insights into either Crohn\\'s disease or ulcerative colitis etiopathogenesis. In this update, we will summarize how the changing epidemiology of IBD associated with modernization can be reconciled with current concepts of disease mechanisms and will discuss studies of clinically significant comorbidity in IBD.

  14. [Chronic inflammatory bowel diseases in cats].

    Science.gov (United States)

    Ghermai, A K

    1989-01-01

    The aetiology of chronic idiopathic intestinal inflammation is unknown. It is characterized by a diffuse infiltration with inflammatory cells into the intestinal mucosa and sometimes submucosa. Cats with chronic intermittent vomiting and diarrhoea, later on accompanied by anorexia and weight loss, are presented. Definitive diagnosis can be obtained by intestinal biopsy only. An immune pathogenesis is suspected, which is supported by the fact, that chronic inflammatory bowel disease responds to steroid therapy.

  15. Current management of the short bowel syndrome.

    Science.gov (United States)

    Thompson, Jon S; Weseman, Rebecca; Rochling, Fedja A; Mercer, David F

    2011-06-01

    Short bowel syndrome is a challenging clinical problem that benefits from a multidisciplinary approach. Much progress has recently been made in all aspects of management. Medical intestinal rehabilitation should be the initial treatment focus, and several new potential pharmacologic agents are being investigated. Surgical rehabilitation using nontransplant procedures in selected patients may further improve intestinal function. Intestinal lengthening procedures are particularly promising. Intestinal transplantation has increasingly been used with improving success in patients with life-threatening complications of intestinal failure.

  16. Recent advances in small bowel diseases: PartⅡ

    Institute of Scientific and Technical Information of China (English)

    Alan BR Thomson; Angeli Chopra; Michael Tom Clandinin; Hugh Freeman

    2012-01-01

    As is the case in all areas of gastroenterology and hepatology,in 2009 and 2010 there were many advances in our knowledge and understanding of small intestinal diseases.Over 1000 publications were reviewed,and the important advances in basic science as well as clinical applications were considered.In Part Ⅱ we review six topics:absorption,short bowel syndrome,smooth muscle function and intestinal motility,tumors,diagnostic imaging,and cystic fibrosis.

  17. Intestinal epithelial cells in inflammatory bowel diseases

    Institute of Scientific and Technical Information of China (English)

    Giulia; Roda; Alessandro; Sartini; Elisabetta; Zambon; Andrea; Calafiore; Margherita; Marocchi; Alessandra; Caponi; Andrea; Belluzzi; Enrico; Roda

    2010-01-01

    The pathogenesis of inflammatory bowel diseases (IBDs) seems to involve a primary defect in one or more of the elements responsible for the maintenance of intestinal homeostasis and oral tolerance. The most important element is represented by the intestinal barrier, a complex system formed mostly by intestinal epithelial cells (IECs). IECs have an active role in producing mucus and regulating its composition; they provide a physical barrier capable of controlling antigen traff ic through the intestinal muco...

  18. Nutritional concerns in pediatric inflammatory bowel disease

    Science.gov (United States)

    2016-01-01

    The pathophysiology and fundamental etiologic mechanism of inflammatory bowel disease (IBD) is not well understood even though therapeutic regimens and drugs are rapidly evolutionary. IBD has complicated connections with genetic, immunologic, gut microbial, environmental, and nutritional factors. It is not clearly well known to the physicians how to feed, what nutrients are more helpful, and what food to be avoided. This review discusses the issues of growth and important nutritional concerns in the management of IBD in childhood. PMID:27462352

  19. Video capsule endoscopy in inflammatory bowel disease

    Science.gov (United States)

    Collins, Paul D

    2016-01-01

    Video capsule endoscopy (VCE) has evolved to become an important tool for the non-invasive examination of the small bowel, which hitherto had been relatively inaccessible to direct visualisation. VCE has been shown to play a role in monitoring the activity of small bowel Crohn’s disease and can be used to assess the response to anti-inflammatory treatment in Crohn’s disease. For those patients with Crohn’s disease who have undergone an intestinal resection, VCE has been assessed as a tool to detect post-operative recurrence. VCE may also aid in the reclassification of patients with a diagnosis of Inflammatory Bowel Disease Unclassified to Crohn’s disease. The evolution of colon capsule endoscopy (CCE) has expanded the application of this technology further. The use of CCE to assess the activity of ulcerative colitis has been described. This advance in capsule technology has also fuelled interest in its potential role as a minimally invasive tool to assess the whole of GI tract opening the possibility of its use for the panenteric assessment of Crohn’s disease. VCE is a safe procedure. However, the risk of a retained capsule is higher in patients with suspected or confirmed Crohn’s disease compared with patients having VCE examination for other indications. A retained video capsule is rare after successful passage of a patency capsule which may be utilised to pre-screen patients undergoing VCE. This paper describes the use of VCE in the assessment of inflammatory bowel disease. PMID:27499830

  20. Review of Inflammatory Bowel Disease in China

    Directory of Open Access Journals (Sweden)

    Lingna Ye

    2013-01-01

    Full Text Available Inflammatory bowel disease mainly consisting of ulcerative colitis and Crohn’s disease has been rising gradually during the last two decades in China. In this review article, we provide the latest epidemiological trends in incidence, prevalence, and mortality of IBD patients in China and summarize the risk factors and genetic susceptibility of Chinese IBD patients. We also compare these characteristics to those of IBD patients in Western countries.

  1. Inflammatory bowel disease: Genetic and epidemiologic considerations

    Institute of Scientific and Technical Information of China (English)

    Judy H Cho

    2008-01-01

    Genome-wide association studies have firmly established that many genomic loci contribute to inflammatory bowel disease, especially in Crohn's disease. These studies have newly-established the importance of the interleukin 23 and autophagy pathways in disease pathogenesis. Future challenges include: (1) the establishment of precisely causal alleles, (2) definition of altered functional outcomes of associated and causal alleles and (3) integration of genetic findings with environmental factors.

  2. Persistent omphalomesenteric duct causing small bowel obstruction in an adult

    Institute of Scientific and Technical Information of China (English)

    Haridimos Markogiannakis; Dimitrios Theodorou; Konstantinos G Toutouzas; Panagiotis Drimousis; Sotirios Georgios Panoussopoulos; Stilianos Katsaragakis

    2007-01-01

    An extremely rare case of persistent omphalomesenteric duct causing small bowel obstruction is presented. A 20-year-old female patient without medical history presented with colicky abdominal pain, vomiting, absence of passage of gas and feces, and abdominal distension of 24 h duration. Physical examination and blood tests were normal. Abdominal X-ray showed small bowel obstruction.Computed tomography of the abdomen demonstrated dilated small bowel and a band originating from the umbilicus and continuing between the small bowel loops;an omphalomesenteric duct remnant was suspected. In exploratory laparotomy, persistent omphalomesenteric duct causing small bowel obstruction was identified and resected. The patient had an uneventful recovery and was discharged on the 5th postoperative day. Although persistent omphalomesenteric duct is an extremely infrequent cause of small bowel obstruction in adult patients, it should be taken into consideration in patients without any previous surgical history.

  3. Ship bow waves

    Institute of Scientific and Technical Information of China (English)

    NOBLESSE Francis; DELHOMMEAU Gerard; LIU Hua; WAN De-cheng; YANG Chi

    2013-01-01

    The bow wave generated by a ship hull that advances at constant speed in calm water is considered.The bow wave only depends on the shape of the ship bow (not on the hull geometry aft of the bow wave).This basic property makes it possible to determine the bow waves generated by a canonical family of ship bows defined in terms of relatively few parameters.Fast ships with fine bows generate overturning bow waves that consist of detached thin sheets of water,which are mostly steady until they hit the main free surface and undergo turbulent breaking up and diffusion.However,slow ships with blunt bows create highly unsteady and turbulent breaking bow waves.These two alternative flow regimes are due to a nonlinear constraint related to the Bernoulli relation at the free surface.Recent results about the overturning and breaking bow wave regimes,and the boundary that divides these two basic flow regimes,are reviewed.Questions and conjectures about the energy of breaking ship bow waves,and free-surface effects on flow circulation,are also noted.

  4. Neurological Manifestations In Inflammatory Bowel Disease

    Directory of Open Access Journals (Sweden)

    youssef HNACH

    2015-06-01

    Full Text Available IntroductionThe purpose of this retrospective study was to report neurological manifestations noted in patients who were monitored for inflammatory bowel disease, in order to document the pathophysiological, clinical, progressive, and therapeutic characteristics of this entity.Material and methodsWe conducted a retrospective study on patients monitored -in the gastroenterology service in Ibn Sina Hospital in Rabat, Morocco- for inflammatory bowel disease from 1992 till 2013 and who developed neurological manifestations during its course. Patients with iatrogenic complications were excluded, as well as patients with cerebrovascular risk factors.ResultsThere were 6 patients, 4 of whom have developed peripheral manifestations. Electromyography enabled the diagnosis to be made and the outcome was favorable with disappearance of clinical manifestations and normalization of the electromyography.The other 2 patients, monitored for Crohn’s disease, developed ischemic stroke. Cerebral computed tomography angiography provided positive and topographic diagnosis. Two patients were admitted to specialized facilities.ConclusionNeurological manifestations in inflammatory bowel disease are rarely reported.  Peripheral neuropathies and stroke remain the most common manifestations. The mechanisms of these manifestations are not clearly defined yet. Currently, we hypothesize the interaction of immune mediators.

  5. Pharmacological nutrition in inflammatory bowel diseases.

    Science.gov (United States)

    Campos, F G; Waitzberg, D L; Teixeira, M G; Mucerino, D R; Kiss, D R; Habr-Gama, A

    2003-01-01

    Inflammatory Bowel Diseases--ulcerative colitis and Crohn's disease--are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted. Total parenteral nutrition has been used to correct and prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with a high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission of disease in adults and promoting growth in children. Recent research has focused on the use of specific nutrients as primary treatment agents. Although some reports have indicated that glutamine, short-chain fatty acids, antioxidants and immunonutrition with omega-3 fatty acids are an important therapeutic alternative in the management of inflammatory bowel diseases, the beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these nutrients still need further evaluation through prospective and randomized trials.

  6. Primary malignant tumors of the small bowel.

    Science.gov (United States)

    Mittal, V K; Bodzin, J H

    1980-09-01

    Primary malignant tumors of the small bowel are uncommon and are often diagnosed at an advanced stage. A 10 year survey (1967 to 1977) of the clinical records at one hospital revealed 39 cases of primary malignant tumors of the small bowel. The most common symptoms were abdominal pain (89.7 percent) and weight loss (77 percent). Six patients presented with complications of enterovesical fistula, bleeding and perforation. Preoperative diagnosis was suspected in 27 cases (69.2 percent). Adenocarcinoma was the most common tumor, followed by carcinoid tumor, lymphoma, leiomyosarcoma and melanoma. The treatment of choice was surgical resection whenever possible. Curative resection was attempted in 25 cases. Adjuvant radiotherapy and chemotherapy was used in four patients with lymphoma. Twenty-seven patients (69.2 percent) are alive from 1 to 6 years after diagnosis and treatment. The 5 year survival rate is 35 percent. Earlier diagnosis is essential if the prognosis for patients with small bowel malignancy is to be improved.

  7. Can Probiotics Cure Inflammatory Bowel Diseases?

    Science.gov (United States)

    Korada, Siva Kumar; Yarla, Nagendra Sastry; Bishayee, Anupam; Aliev, Gjumrakch; Aruna Lakshmi, K; Arunasree, M K; Dananajaya, B L; Mishra, Vijendra

    2016-01-01

    Gastrointestinal (GI) disorders, especially microbial dysbiosis play role in several GI ailments such as irritable bowel syndrome, colorectal cancer, inflammatory bowel diseases, and antibiotic-associated diarrhoea. Role of inflammatory bowel disease (IBD) is multifactorial as it involves loss of maintaining intestinal epithelial barrier integrity, increased release of pro-inflammatory molecules, and microbial dysbiosis in gut microflora. Some specific pathogens also play a key role in the IBD development. The origin and causation are still in unfathomable condition and the exact root cause is unknown. Recently probiotic studies have been gaining importance because of their positive responses in their IBD experimental results. According to joint Food and Agricultural Organisation/World Health Organisation working group, probiotics are defined as live microorganisms which when administered in adequate amount confer health benefit on the host. These live beneficial microorganisms are considered helpful in improving gut colonization and perseverance thereby improves prophylactic effect. In the direction of IBD research, a number of studies are needed to standardize its methodology and its applicability on human usage. The particular review presents an overview of gut microflora and its impact on host health, types of IBD and existing therapies to treat this disorder, mechanism of several probiotic actions, role of probiotics in IBD prevention with their supporting evidences.

  8. BOWEL INVOLVEMENT IN PATIENTS WITH SPONDYLOARTHRITIS

    Directory of Open Access Journals (Sweden)

    A. E. Karateev

    2015-01-01

    Full Text Available The pathogenetic  and clinical association between spondyloarthritis  (SpA and inflammatory bowel diseases (IBD is well known. Ulcerative colitis and Crohn's disease are more common  in patients with SpA than in general population. In turn, the involvement of the spine and peripheral joints is a typical systemic manifestation  of IBD. But at the same time at least half of patients with SpA have endoscopic and histological signs of chronic inflammation of the small and large intestine mucosa, which are unaccompanied by characteristic  clinical manifestations and cannot considered within a specific nosological entity. The importance  of this pathology has been unknown until the present time. Should asymptomatic  bowel inflammation be considered as a precursor of true IBD, which methods should be used to diagnose bowel involvement and how the presence of this pathology affects the choice of rational pharmacotherapy for SpA? This review analyzes the basic literature data concerning this problem.

  9. Occult spondyloarthritis in inflammatory bowel disease.

    Science.gov (United States)

    Bandinelli, Francesca; Manetti, Mirko; Ibba-Manneschi, Lidia

    2016-02-01

    Spondyloarthritis (SpA) is a frequent extra-intestinal manifestation in patients with inflammatory bowel disease (IBD), although its real diffusion is commonly considered underestimated. Abnormalities in the microbioma and genetic predisposition have been implicated in the link between bowel and joint inflammation. Otherwise, up to date, pathogenetic mechanisms are still largely unknown and the exact influence of the bowel activity on rheumatic manifestations is not clearly explained. Due to evidence-based results of clinical studies, the interest on clinically asymptomatic SpA in IBD patients increased in the last few years. Actually, occult enthesitis and sacroiliitis are discovered in high percentages of IBD patients by different imaging techniques, mainly enthesis ultrasound (US) and sacroiliac joint X-ray examinations. Several diagnostic approaches and biomarkers have been proposed in an attempt to correctly classify and diagnose clinically occult joint manifestations and to define clusters of risk for patient screening, although definitive results are still lacking. The correct recognition of occult SpA in IBD requires an integrated multidisciplinary approach in order to identify common diagnostic and therapeutic strategies. The use of inexpensive and rapid imaging techniques, such as US and X-ray, should be routinely included in daily clinical practice and trials to correctly evaluate occult SpA, thus preventing future disability and worsening of quality of life in IBD patients.

  10. Optimal Diagnostic Approaches for Patients with Suspected Small Bowel Disease

    Science.gov (United States)

    Kim, Jae Hyun; Moon, Won

    2016-01-01

    While the domain of gastrointestinal endoscopy has made great strides over the last several decades, endoscopic assessment of the small bowel continues to be challenging. Recently, with the development of new technology including video capsule endoscopy, device-assisted enteroscopy, and computed tomography/magnetic resonance enterography, a more thorough investigation of the small bowel is possible. In this article, we review the systematic approach for patients with suspected small bowel disease based on these advanced endoscopic and imaging systems. PMID:27334413

  11. The diagnostic role of MDCT enterography in small bowel lesions

    OpenAIRE

    Hasan I. Megally; Hosam eldin Mohamed Elmalah; Gehan S. Seifeldein; Nisreen Adel Abbas; Hussien Ahmed Elamin

    2015-01-01

    Purpose: To evaluate the role of MDCT enterography in the diagnosis of small bowel diseases. Patient and methods: Thirty nine patients suspected to have small bowel diseases were examined with 64 MDCT enterography. Result: MDCT enterography easily diagnosed small intestinal diseases which confirmed with histopathological results, operative data and follow up. Conclusions: MDCT can be used as a front-line imaging and one stop imaging modality for the detection of small bowel diseases....

  12. Mechanical bowel preparation in elective open colon surgery

    OpenAIRE

    Fa-Si-Oen, Patrick Regnier

    2006-01-01

    Mechanical bowel preparation is a long standing practice in elective open colon surgery dating from the 1970's. It has always been believed to reduce the rate of postoperative complications in the form of anastomotic leakage and wound infection. In this thesis we broadly and thoroughly examine the various aspects and the value of mechanical bowel preparation in elective open colon surgery. - Mechanical bowel preparation in elective open colon surgery does not reduce the rate of anastomotic le...

  13. CT of complicated inflammatory bowel disease in children

    Energy Technology Data Exchange (ETDEWEB)

    Riddlesberger, M.M. Jr.

    1985-09-01

    Most children with inflammatory bowel disease do not need a CT scan. However, when the course becomes complicated if often is necessary to evaluate what is happening outside the bowel lumen. CT is the examination of choice for that evaluation. With CT, the presence and extent of an abscess can be diagnosed and followed; fistulae can be detected; bowel wall and mesenteric thickening can generally be differentiated from an abscess.

  14. Intestinal microbiota in pathophysiology and management of irritable bowel syndrome

    OpenAIRE

    Lee, Kang Nyeong; Lee, Oh Young

    2014-01-01

    Irritable bowel syndrome (IBS) is a functional bowel disorder without any structural or metabolic abnormalities that sufficiently explain the symptoms, which include abdominal pain and discomfort, and bowel habit changes such as diarrhea and constipation. Its pathogenesis is multifactorial: visceral hypersensitivity, dysmotility, psychosocial factors, genetic or environmental factors, dysregulation of the brain-gut axis, and altered intestinal microbiota have all been proposed as possible cau...

  15. Methylglyoxal Induces Systemic Symptoms of Irritable Bowel Syndrome

    OpenAIRE

    Shuang Zhang; Taiwei Jiao; Yushuai Chen; Nan Gao; Lili Zhang; Min Jiang

    2014-01-01

    Patients with irritable bowel syndrome (IBS) show a wide range of symptoms including diarrhea, abdominal pain, changes in bowel habits, nausea, vomiting, headache, anxiety, depression and cognitive impairment. Methylglyoxal has been proved to be a potential toxic metabolite produced by intestinal bacteria. The present study was aimed at investigating the correlation between methylglyoxal and irritable bowel syndrome. Rats were treated with an enema infusion of methylglyoxal. Fecal water conte...

  16. Nutritional impact of inflammatory bowel diseases on children and adolescents☆

    OpenAIRE

    dos Santos, Gilton Marques; Santos,Gilton Marques dos; Silva, Luciana Rodrigues; Santana, Genoile Oliveira

    2014-01-01

    OBJECTIVE: To perform a sistematiy review of the literature about the nutritional impact of inflammatory bowel diseases in children and adolescents. DATA SOURCES: A systematic review was performed using PubMed/MEDLINE, LILACS and SciELO databases, with inclusion of articles in Portuguese and in English with original data, that analyzed nutritional aspects of inflammatory bowel diseases in children and adolescents. The initial search used the terms "inflammatory bowel diseases" and "children" ...

  17. Nutritional impact of inflammatory bowel diseases on children and adolescents

    OpenAIRE

    Gilton Marques dos Santos; Luciana Rodrigues Silva; Genoile Oliveira Santana

    2014-01-01

    OBJECTIVE: To perform a sistematiy review of the literature about the nutritional impact of inflammatory bowel diseases in children and adolescents.DATA SOURCES: A systematic review was performed using PubMed/MEDLINE, LILACS and SciELO databases, with inclusion of articles in Portuguese and in English with original data, that analyzed nutritional aspects of inflammatory bowel diseases in children and adolescents. The initial search used the terms "inflammatory bowel diseases" and "children" o...

  18. Venous Small Bowel Infarction: Intraoperative Laser Doppler Flowmetry Discriminates Critical Blood Supply and Spares Bowel Length

    Directory of Open Access Journals (Sweden)

    S. A. Käser

    2012-01-01

    Full Text Available Introduction. In mesenteric infarction due to arterial occlusion, laser Doppler flowmetry and spectrometry are known reliable noninvasive methods for measuring microvascular blood flow and oxygen utilisation. Case Presentation. As an innovation we used these methods in a patient with acute extensive mesenteric infarction due to venous occlusion, occurring after radical right hemicolectomy. Aiming to avoid short bowel syndrome, we spared additional 110 cm of small bowel, instead of leaving only 80 centimetres of clinically viable small bowel in situ. The pathological examination showed only 5 mm of vital mucosa to be left distal to the dissection margin. No further interventions were necessary. Conclusion. Laser doppler flowmetry and spectrometry are potentially powerful methods to assist the surgeon’s decision-making in critical venous mesenteric perfusion, thus having an important impact on clinical outcome.

  19. Characterizing micro-macro transitions with slow light

    CERN Document Server

    Zhou, Zhifan; Glasser, Ryan T; Qin, Zhongzhong; Fang, Yami; Jing, Jietai; Zhang, Weiping

    2016-01-01

    The transition between the microscopic to the macroscopic world is of broad fundamental and technological significance. Optical parametric amplifiers allow for amplifying single photons to the macroscopic level, but the underlying temporal dynamics are still not well understood. Slow light, in which the group velocity is delayed via quantum interference, is an effective tool to interrogate the temporal dynamics of light-matter interactions. Here, we demonstrate a scheme to characterize micro-macro transitions with slow light based on a four-wave mixing linear amplification process in a hot rubidium vapour. The scheme exhibits strong dispersion which is sensitive to the input's change at the single-photon level, resulting in a nonlinear decay of the micro-macro transition time with the increased microscopic input. The present system is suitable for the study of the relevant time scale of quantum-to-classical transitions and the potential impact from fundamental effects such as gravity, as indicated by recent p...

  20. Nonlinear light propagation in chalcogenide photonic crystal slow light waveguides.

    Science.gov (United States)

    Suzuki, Keijiro; Baba, Toshihiko

    2010-12-06

    Optical nonlinearity can be enhanced by the combination of highly nonlinear chalcogenide glass and photonic crystal waveguides (PCWs) providing strong optical confinement and slow-light effects. In a Ag-As(2)Se(3) chalcogenide PCW, the effective nonlinear parameter γeff reaches 6.3 × 10(4) W(-1)m(-1), which is 200 times larger than that in Si photonic wire waveguides. In this paper, we report the detailed design, fabrication process, and the linear and nonlinear characteristics of this waveguide at silica fiber communication wavelengths. We show that the waveguide exhibits negligible two-photon absorption, and also high-efficiency self-phase modulation and four-wave mixing, which are assisted by low-dispersion slow light.

  1. An exact solution of the slow-light problem

    CERN Document Server

    Rybin, A V; Bishop, A R

    2004-01-01

    We investigate propagation of a slow-light soliton in atomic vapors and Bose-Einstein condensates described by the nonlinear Lambda-model. We show that the group velocity of the soliton monotonically decreases with the intensity of the controlling laser field, which decays exponentially after the laser is switched off. The shock wave of the vanishing controlling field overtakes the slow soliton and stops it, while the optical information is recorded in the medium in the form of spatially localized polarization. We find an explicit exact solution describing the whole process within the slowly varying amplitude and phase approximation. Our results point to the possibility of addressing spatially localized memory formations and moving these memory bits along the medium in a controllable fashion.

  2. Modulational instability of plasma waves in two dimensions

    DEFF Research Database (Denmark)

    Karpman, V.I.; Lynov, Jens-Peter; Michelsen, Poul

    1996-01-01

    The nonlinear behavior of whistler waves coupled to either fast magnetosonic waves (FMS) or slow magnetosonic waves (SMS) is investigated in two spatial dimensions. For each branch our investigation is based on a numerical solution of a reduced set of equations consisting of two partial...... differential equations, of which one, describing the evolution of the whistler wave envelope, is complex of first order in time and the other, describing the slow response of the medium in which the whistler wave is propagating, is real and of second order in time. These equations were solved in a two...... of nonlinear waves in dispersive media....

  3. Harbinger of plague: a bad case of gay bowel syndrome.

    Science.gov (United States)

    Scarce, M

    1997-01-01

    In 1976, a group of physicians in private proctologic practice in New York City coined the illness "Gay Bowel Syndrome" in reference to a constellation of gay male anorectal disorders. Through analysis of biomedical discourse and popular media, it is apparent that Gay Bowel Syndrome is an essentialized category of difference that is neither gay-specific, confined to the bowel, nor a syndrome. The use and diagnosis of Gay Bowel Syndrome must be abandoned before it further lends itself to the formation of social policies and governing practices that seek to force gay male bodies into positions of social, cultural, and political subordination.

  4. Laparoscopic Techniques: What is the Role in Inflammatory Bowel Disease?

    Directory of Open Access Journals (Sweden)

    Tracy L Hull

    1995-01-01

    Full Text Available Laparoscopic cholecystectomy has quickly become the preferred technique for removing the gallbladder. Real advantages in the area of laparoscopic gallbladder removal have spurred interest towards other areas of laparoscopic surgery. There has been interest in laparoscopic bowel surgery but this approach has not gained popularity as quickly as gallbladder surgery. Reasons surround the fact that the bowel is a continuous organ (versus an end organ like the gallbladder laden with bacteria and it has a rich blood supply. These differences make laparoscopic bowel surgery more difficult and challenging. If inflammatory bowel disease (IBD is considered, the indications to approach surgery laparoscopically fall into two categories: current and future indications. The current indications are diagnostic laparoscopy, fecal diversion, limited bowel resections with extracorporeal anastomosis and stoma closures. Future indications include laparoscopic subtotal colectomy and laparoscopic assisted pelvic pouch procedures. As experience is gained and laparoscopic instruments are modified and refined for bowel surgery, intracorporeal anastomosis and more extensive bowel resections will be feasible. Currently laparoscopic bowel surgery can be done in select circumstances for problems associated with IBD. It has yet to be proven if doing the surgery laparoscopically provides advantages for bowel surgery as has been demonstrated with gallbladder surgery. Prospective studies are underway to answer these questions.

  5. Plant domestication slows pest evolution.

    Science.gov (United States)

    Turcotte, Martin M; Lochab, Amaneet K; Turley, Nash E; Johnson, Marc T J

    2015-09-01

    Agricultural practices such as breeding resistant varieties and pesticide use can cause rapid evolution of pest species, but it remains unknown how plant domestication itself impacts pest contemporary evolution. Using experimental evolution on a comparative phylogenetic scale, we compared the evolutionary dynamics of a globally important economic pest - the green peach aphid (Myzus persicae) - growing on 34 plant taxa, represented by 17 crop species and their wild relatives. Domestication slowed aphid evolution by 13.5%, maintained 10.4% greater aphid genotypic diversity and 5.6% higher genotypic richness. The direction of evolution (i.e. which genotypes increased in frequency) differed among independent domestication events but was correlated with specific plant traits. Individual-based simulation models suggested that domestication affects aphid evolution directly by reducing the strength of selection and indirectly by increasing aphid density and thus weakening genetic drift. Our results suggest that phenotypic changes during domestication can alter pest evolutionary dynamics.

  6. The TTI slowness surface approximation

    KAUST Repository

    Stovas, A.

    2011-01-01

    The relation between the vertical and horizontal slownesses, better known as the dispersion relation, for a transversely isotropic media with titled symmetry axis {left parenthesis, less than bracket}TTI{right parenthesis, greater than bracket} requires solving a quartic polynomial, which does not admit a practical explicit solution to be used, for example, in downward continuation. Using a combination of perturbation theory with respect to the anelliptic parameter and Shanks transform to improve the accuracy of the expansion, we develop an explicit formula for the dispersion relation that is highly accurate for all practical purposes. It also reveals some insights into the anisotropy parameter dependency of the dispersion relation including the low impact that the anelliptic parameter has on the vertical placement of reflectors for small tilt in the symmetry angle. © 2011 Society of Exploration Geophysicists.

  7. Primary Amyloidosis Presenting as Small Bowel Encapsulation

    Directory of Open Access Journals (Sweden)

    Jennifer Jones

    2004-01-01

    Full Text Available Amyloidosis is a pathological process which encompasses a spectrum of diseases that result from extracellular deposition of pathological fibrillar proteins. Clinical presentations vary depending on the organs involved. There is no documented case of amyloidosis presenting as small bowel encapsulation. A previously healthy 62-year-old man developed a small bowel obstruction in 1997. At surgery, a peculiar membrane encasing his entire small bowel was discovered. This appeared to have no vascularity and was removed without difficulty, exposing a grossly normal bowel. Histopathology revealed thick bands of collagen overlying the peritoneal surface, which was congo red positive and showed apple green birefringence. The findings were consistent with encapsulating peritonitis due to amyloidosis. There was no history or symptoms of any chronic inflammatory condition and he became symptom-free postoperatively. An abdominal fat pad biopsy failed to demonstrate amyloidosis. Endoscopic duodenal biopsies revealed classical primary amyloidosis. Quantitative immunoglobulins, lactate dehydrogenase, C3, C4 and beta-2 microglobulin were normal. Protein electrophoresis identified monoclonal paraprotein, immunoglobulin G lambda 3.7 g/L. Bone marrow biopsy and aspirate revealed only a mild plasmacytosis (5% to 10%. Echocardiogram and skeletal survey were normal. He had mild proteinuria. Complete blood count, C-reactive protein, calcium, albumin and total protein were normal. No specific therapy was instituted. In January of 1998 the patient remained asymptomatic with no gastrointestinal, cardiovascular or constitutional symptoms. He had developed nephrotic range proteinuria (3.95 g/24 h, microalbuminuria, hypoalbuminemia and a renal biopsy consistent with renal amyloidosis. In 1999 there was an increase in the monoclonal paraprotein (6.2 g/L. The remaining investigations were normal except for an echocardiogram which showed left ventricular hypertrophy but a normal

  8. An immunoglobulin G-4 related sclerosing disease of the small bowel: CT and small bowel series findings

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Young Hwan; Hwang, Dae Hyun; Min, Seon Jeong [Dept. of Radiology, Hallym University Dongtan Sacred Heart Hospital, Hwaseong (Korea, Republic of); Woo, Ji Young; Kim, Jeong Won; Hong, Hye Sook; Yang, Ik; Lee, Yul [Hallym University Kangnam Sacred Heart Hospital, Seoul (Korea, Republic of)

    2013-10-15

    Immunoglobulin G4 (IgG4)-related sclerosing disease is rare and is known to involve various organs. We present a case of histologically proven IgG4-related sclerosing disease of the small bowel with imaging findings on computed tomography (CT) and small bowel series. CT showed irregular wall thickening, loss of mural stratification and aneurysmal dilatation of the distal ileum. Small bowel series showed aneurysmal dilatations, interloop adhesion with traction and abrupt angulation.

  9. On the generation of internal wave modes by surface waves

    Science.gov (United States)

    Harlander, Uwe; Kirschner, Ian; Maas, Christian; Zaussinger, Florian

    2016-04-01

    Internal gravity waves play an important role in the ocean since they transport energy and momentum and the can lead to mixing when they break. Surface waves and internal gravity waves can interact. On the one hand, long internal waves imply a slow varying shear current that modifies the propagation of surface waves. Surface waves generated by the atmosphere can, on the other hand, excite internal waves by nonlinear interaction. Thereby a surface wave packet consisting of two close frequencies can resonate with a low frequency internal wave (Phillips, 1966). From a theoretical point of view, the latter has been studied intensively by using a 2-layer model, i.e. a surface layer with a strong density contrast and an internal layer with a comparable weak density contrast (Ball, 1964; Craig et al., 2010). In the present work we analyse the wave coupling for a continuously stratified fluid using a fully non-linear 2D numerical model (OpenFoam) and compare this with laboratory experiments (see Lewis et al. 1974). Surface wave modes are used as initial condition and the time development of the dominant surface and internal waves are studied by spectral and harmonic analysis. For the simple geometry of a box, the results are compared with analytical spectra of surface and gravity waves. Ball, F.K. 1964: Energy transfer between external and internal gravity waves. J. Fluid Mech. 19, 465. Craig, W., Guyenne, P., Sulem, C. 2010: Coupling between internal and surface waves. Natural Hazards 57, 617-642. Lewis, J.E., Lake, B.M., Ko, D.R.S 1974: On the interaction of internal waves and surfacr gravity waves, J. Fluid Mech. 63, 773-800. Phillips, O.M. 1966: The dynamics of the upper ocean, Cambridge University Press, 336pp.

  10. Magnetohydrodynamic waves within the medium separated by the plane shock wave or rotational discontinuity

    Directory of Open Access Journals (Sweden)

    A. A. Lubchich

    2005-07-01

    Full Text Available Characteristics of small amplitude plane waves within the medium separated by the plane discontinuity into two half spaces are analysed. The approximation of the ideal one-fluid magnetohydrodynamics (MHD is used. The discontinuities with the nonzero mass flux across them are mainly examined. These are fast or slow shock waves and rotational discontinuities. The dispersion equation for MHD waves within each of half space is obtained in the reference frame connected with the discontinuity surface. The solution of this equation permits one to determine the wave vectors versus the parameter cp, which is the phase velocity of surface discontinuity oscillations. This value of cp is common for all MHD waves and determined by an incident wave or by spontaneous oscillations of the discontinuity surface. The main purpose of the study is a detailed analysis of the dispersion equation solution. This analysis let us draw the following conclusions. (I For a given cp, ahead or behind a discontinuity at most, one diverging wave can transform to a surface wave damping when moving away from the discontinuity. The surface wave can be a fast one or, in rare cases, a slow, magnetoacoustic one. The entropy and Alfvén waves always remain in a usual homogeneous mode. (II For certain values of cp and parameters of the discontinuity behind the front of the fast shock wave, there can be four slow magnetoacoustic waves, satisfying the dispersion equation, and none of the fast magnetoacoustic waves. In this case, one of the four slow magnetoacoustic waves is incident on the fast shock wave from the side of a compressed medium. It is shown that its existence does not contradict the conditions of the evolutionarity of MHD shock waves. The four slow magnetoacoustic waves, satisfying the dispersion equation, can also exist from either side of a slow shock wave or rotational discontinuity. (III The

  11. Extending Magnetohydrodynamics to the Slow Dynamics of Collisionless Plasmas

    Science.gov (United States)

    Passot, T.; Sulem, P. L.; Hunana, P.

    2012-01-01

    A fluid approach aimed to provide a consistent description of the slow dynamics of a collisionless plasma, is presented. In this regime, both Landau damping and finite Larmor radius effects cannot be ignored. Two models are discussed; one retains the dynamics at sub-ionic scales, while the other is restricted to scales larger than the ion gyroscale. Special attention is paid to the capability of these approaches to accurately reproduce the properties of linear waves that are known to play an important role, for example, in the small-scale dynamics of solar wind turbulence.

  12. Minimally invasive approaches for the treatment of inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Marco Zoccali; Alessandro Fichera

    2012-01-01

    Despite significant improvements in medical management of inflammatory bowel disease,many of these patients still require surgery at some point in the course of their disease.Their young age and poor general conditions,worsened by the aggressive medical treatments,make minimally invasive approaches particularly enticing to this patient population.However,the typical inflammatory changes that characterize these diseases have hindered wide diffusion of laparoscopy in this setting,currently mostly pursued in high-volume referral centers,despite accumulating evidences in the literature supporting the benefits of minimally invasive surgery.The largest body of evidence currently available for terminal ileal Crohn's disease shows improved short term outcomes after laparoscopic surgery,with prolonged operative times.For Crohn's colitis,high quality evidence supporting laparoscopic surgery is lacking.Encouraging preliminary results have been obtained with the adoption of laparoscopic restorative total proctocolectomy for the treatment of ulcerative colitis.A consensus about patients' selection and the need for staging has not been reached yet.Despite the lack of conclusive evidence,a wave of enthusiasm is pushing towards less invasive strategies,to further minimize surgical trauma,with single incision laparoscopic surgery being the most realistic future development.

  13. Tree-wave mixing of ordinary and backward electromagnetic waves: extraordinary transients

    CERN Document Server

    Slabko, Vitaly V; Tkachenko, Viktor A; Myslivets, Sergey A

    2016-01-01

    Three-wave mixing of ordinary and backward electromagnetic waves in pulsed regime is investigated in the metamaterials, which enable co-existence and phase matching of such waves. It is shown that opposite direction of phase velocity and energy flux in backward waves gives rise to extraordinary transient processes in greatly enhanced optical parametric amplification and in frequency up or down shifting nonlinear reflectivity. The discovered transients resemble slowed response of an oscillator on pulsed excitation in the vicinity of its resonance

  14. Subtypes of irritable bowel syndrome based on abdominal pain/discomfort severity and bowel pattern

    Science.gov (United States)

    Irritable bowel syndrome (IBS) has traditionally been classified by stooling pattern (e.g., diarrhea-predominant). However, other patterns of symptoms have long been recognized, e.g., pain severity. Our objective was to examine the utility of subtyping women with IBS based on pain/discomfort severit...

  15. Slow electrostatic fluctuations generated by beam-plasma interaction

    CERN Document Server

    Pommois, Karen; Pezzi, Oreste; Veltri, Pierluigi

    2016-01-01

    Eulerian simulations of the Vlasov-Poisson equations have been employed to analyze the excitation of slow electrostatic fluctuations (with phase speed close to the electron thermal speed), due to a beam-plasma interaction, and their propagation in linear and nonlinear regime. In 1968, O'Neil and Malmberg [Phys. Fluids {\\bf 11}, 1754 (1968)] dubbed these waves "beam modes". In the present paper, it is shown that, in the presence of a cold and low density electron beam, these beam modes can become unstable and then survive Landau damping unlike the Langmuir waves. When an electron beam is launched in a plasma of Maxwellian electrons and motionless protons and this initial equilibrium is perturbed by a monochromatic density disturbance, the electric field amplitude grows exponentially in time and then undergoes nonlinear saturation, associated with the kinetic effects of particle trapping and phase space vortex generation. Moreover, if the initial density perturbation is setup in the form of a low amplitude rand...

  16. Slow dynamics in proteins and polymer chains

    Science.gov (United States)

    Hu, Chin-Kun

    2013-02-01

    How a biological system can maintain in a non-equilibrium state for a very long time and why proteins aggregate are still not well understood. In this paper, we first review critical slow down of the Ising model and slow relaxation of a spin-glass model at low temperatures. The data indicate that relaxation of the spin glass model at low temperatures can be slower than the critical slowing down of the Ising model. We then review recent molecular dynamics results for the slow relaxation of polymer chains and experimental data for the glassy behavior of collagen fibrils. The slow dynamics in polymer chains and collagen fibrils can provide clues for understanding why a biological system can maintain in a non-equilibrium state for a very long time, and how to slow down protein aggregation related to neurodegenerative diseases.

  17. Sensory characterization of bowel cleansing solutions

    Institute of Scientific and Technical Information of China (English)

    Ala I Sharara; Hamza Daroub; Camille Georges; Rani Shayto; Ralph Nader; Jean Chalhoub; Ammar Olabi

    2016-01-01

    AIM: To evaluate the sensory characteristics of commercial bowel cleansing preparations.METHODS: Samples of 4 commercially available bowel cleansing preparations, namely polyethylene glycol electrolyte solution(PEG), PEG + ascorbic acid(PEG-Asc), sodium picosulfate(SPS), and oral sodium sulfate(OSS) were prepared according to the manufacturer’s instructions. Descriptive analysis was conducted(n = 14) using a 15-cm line scale with the Compusense at-hand? sensory evaluation software. Acceptability testing(n = 80) was conducted using the 9-point hedonic scale. In addition, a Just-About-Right(JAR) scale was included for the four basic tastes to determine their intensity compatibility with acceptability levels in the products.RESULTS: Samples were significantly different, in descriptive analysis, for all attributes(P < 0.05) except for sweetness. SPS received the highest ratings for turbidity, viscosity appearance, orange odor and orange flavor; PEG-Asc for citrus odor and citrus flavor; OSS for sweetener taste, sweet aftertaste, bitterness, astringency, mouthcoating, bitter aftertaste and throatburn, and along with PEG-Asc, the highest ratings for saltiness, sourness and adhesiveness. Acceptability results showedsignificant differences between the various samples(P < 0.05). SPS received significantly higher ratings for overall acceptability, acceptability of taste, odor and mouthfeel(P < 0.05). JAR ratings showed that PEG and PEG-Asc were perceived as slightly too salty; SPS and OSS were slightly too sweet, while SPS, PEG-Asc and OSS were slightly too sour and OSS slightly too bitter. While using small sample volumes was necessary to avoid unwanted purgative effects, acceptability ratings do not reflect the true effect of large volumes intake thus limiting the generalization of the results.CONCLUSION: Further improvements are needed to enhance the sensory profile and to optimize the acceptability for better compliance with these bowel cleansing solutions.

  18. Inflammatory bowel diseases: principles of nutritional therapy.

    Science.gov (United States)

    Campos, Fábio Guilherme; Waitzberg, Dan L; Teixeira, Magaly Gemio; Mucerino, Donato Roberto; Habr-Gama, Angelita; Kiss, Desidério R

    2002-01-01

    Inflammatory Bowel Diseases - ulcerative colitis and Crohn's disease- are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Total parenteral nutrition has been used to correct and to prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission in adults and promoting growth in children. Due to its low complication rate and lower costs, enteral nutrition should be preferred over total parenteral nutrition whenever possible. Both present equal effectiveness in primary therapy for remission of active Crohn's disease. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted, especially in patients presumed to need total parenteral nutrition. Recent research has focused on the use of nutrients as primary treatment agents. Immunonutrition is an important therapeutic alternative in the management of inflammatory bowel diseases, modulating the inflammation and changing the eicosanoid synthesis profile. However, beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these and other nutrients (glutamine, short-chain fatty acids, antioxidants) still need further evaluation through prospective and randomized trials.

  19. Inflammatory bowel diseases: principles of nutritional therapy

    Directory of Open Access Journals (Sweden)

    Campos Fábio Guilherme

    2002-01-01

    Full Text Available Inflammatory Bowel Diseases - ulcerative colitis and Crohn's disease- are chronic gastrointestinal inflammatory diseases of unknown etiology. Decreased oral intake, malabsorption, accelerated nutrient losses, increased requirements, and drug-nutrient interactions cause nutritional and functional deficiencies that require proper correction by nutritional therapy. The goals of the different forms of nutritional therapy are to correct nutritional disturbances and to modulate inflammatory response, thus influencing disease activity. Total parenteral nutrition has been used to correct and to prevent nutritional disturbances and to promote bowel rest during active disease, mainly in cases of digestive fistulae with high output. Its use should be reserved for patients who cannot tolerate enteral nutrition. Enteral nutrition is effective in inducing clinical remission in adults and promoting growth in children. Due to its low complication rate and lower costs, enteral nutrition should be preferred over total parenteral nutrition whenever possible. Both present equal effectiveness in primary therapy for remission of active Crohn's disease. Nutritional intervention may improve outcome in certain individuals; however, because of the costs and complications of such therapy, careful selection is warranted, especially in patients presumed to need total parenteral nutrition. Recent research has focused on the use of nutrients as primary treatment agents. Immunonutrition is an important therapeutic alternative in the management of inflammatory bowel diseases, modulating the inflammation and changing the eicosanoid synthesis profile. However, beneficial reported effects have yet to be translated into the clinical practice. The real efficacy of these and other nutrients (glutamine, short-chain fatty acids, antioxidants still need further evaluation through prospective and randomized trials.

  20. Small bowel angiodysplasia and novel disease associations: a cohort study.

    LENUS (Irish Health Repository)

    Holleran, Grainne

    2013-04-01

    Gastrointestinal angiodysplasias recurrently bleed, accounting for 3-5% of obscure gastrointestinal bleeding. The advent of small bowel capsule endoscopy (SBCE) has led to an increased recognition of small bowel angiodysplasias (SBAs) but little is known about their etiology. Previous small cohorts and case reports suggest an equal gender incidence and associations with cardiovascular disease, renal impairment, and coagulopathies.