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Sample records for bowel slow wave

  1. Inhibitory Effects and Sympathetic Mechanisms of Distension in the Distal Organs on Small Bowel Motility and Slow Waves in Canine.

    Science.gov (United States)

    Song, Jun; Yin, Jieyun; Chen, Jiande D Z

    2015-12-01

    Rectal distension (RD) is known to induce intestinal dysmotility. Few studies were performed to compare effects of RD, colon distension (CD) and duodenal distension (DD) on small bowel motility. This study aimed to investigate effects and underlying mechanisms of distensions in these regions on intestinal motility and slow waves. Eight dogs chronically implanted with a duodenal fistula, a proximal colon fistula, and intestinal serosal electrodes were studied in six sessions: control, RD, CD, DD, RD + guanethidine, and CD + guanethidine. Postprandial intestinal contractions and slow waves were recorded for the assessment of intestinal motility. The electrocardiogram was recorded for the assessment of autonomic functions. (1) Isobaric RD and CD suppressed intestinal contractions (contractile index: 6.0 ± 0.4 with RD vs. 9.9 ± 0.9 at baseline, P = 0.001, 5.3 ± 0.2 with CD vs. 7.7 ± 0.8 at baseline, P = 0.008). Guanethidine at 3 mg/kg iv was able to partially block the effects. (2) RD and CD reduced the percentage of normal intestinal slow waves from 92.1 ± 2.8 to 64.2 ± 3.4 % (P waves (P > 0.05). (4) The spectral analysis of the heart rate variability showed that both RD and CD increased sympathetic activity (LF) and reduced vagal activity (HF) (P waves, which were mediated via the sympathetic pathway. However, DD at a site proximal to the measurement site did not seem to impair small intestinal contractions or slow waves.

  2. 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.

  3. Source Modeling Sleep Slow Waves

    National Research Council Canada - National Science Library

    Michael Murphy; Brady A. Riedner; Reto Huber; Marcello Massimini; Fabio Ferrarelli; Giulio Tononi; Marcus E. Raichle

    2009-01-01

    .... Here we use high-density EEG (hd-EEG) source modeling to show that individual spontaneous slow waves have distinct cortical origins, propagate uniquely across the cortex, and involve unique subsets of cortical structures...

  4. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    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 ...

  5. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  6. Electroencephalographic slow waves prior to sleepwalking episodes.

    Science.gov (United States)

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

    2014-12-01

    Recent studies have suggested that the onset of sleepwalking episodes may be preceded by fluctuations in slow-wave sleep electroencephalographic characteristics. However, whether or not such fluctuations are specific to sleepwalking episodes or generalized to all sleep-wake transitions in sleepwalkers remains unknown. The goal of this study was to compare spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) as well as slow oscillation density before the onset of somnambulistic episodes versus non-behavioral awakenings recorded from the same group of sleepwalkers. A secondary aim was to describe the time course of observed changes in slow-wave activity and slow oscillations during the 3 min immediately preceding the occurrence of somnambulistic episodes. Twelve adult sleepwalkers were investigated polysomnographically during the course of one night. Slow-wave activity and slow oscillation density were significantly greater prior to patients' somnambulistic episodes as compared with non-behavioral awakenings. However, there was no evidence for a gradual increase over the 3 min preceding the episodes. Increased slow-wave activity and slow oscillation density appear to be specific to sleepwalking episodes rather than generalized to all sleep-wake transitions in sleepwalkers. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Human gamma oscillations during slow wave sleep.

    Directory of Open Access Journals (Sweden)

    Mario Valderrama

    Full Text Available Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS. At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz and high (60-120 Hz frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves ("IN-phase" pattern, confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave ("ANTI-phase" pattern. This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks.

  8. Slow light by Bloch surface wave tunneling.

    Science.gov (United States)

    Koju, Vijay; Robertson, William M

    2014-06-30

    We demonstrate a slow light configuration that makes use of Bloch Surface Waves as an intermediate excitation in a double-prism tunneling configuration. This method is simple compared to the more usual technique for slowing light using the phenomenon of electromagnetically induced transparency in atomic gases or doped ionic crystals operated at temperatures below 4 K. Using a semi-numerical approach, we show that a 1D photonic crystal, a multilayer structure composed of alternating layers of TiO(2) and SiO(2), can be used to slow down light by a factor of up to 400. The results also show that better control of the speed of light can be achieved by changing the number of bilayers and the air-gap thickness appropriately.

  9. Analysis of slow-wave activity and slow-wave oscillations prior to somnambulism.

    Science.gov (United States)

    Jaar, Olivier; Pilon, Mathieu; Carrier, Julie; Montplaisir, Jacques; Zadra, Antonio

    2010-11-01

    STUDY OBJECTIVIES: several studies have investigated slow wave sleep EEG parameters, including slow-wave activity (SWA) in relation to somnambulism, but results have been both inconsistent and contradictory. The first goal of the present study was to conduct a quantitative analysis of sleepwalkers' sleep EEG by studying fluctuations in spectral power for delta (1-4 Hz) and slow delta (0.5-1 Hz) before the onset of somnambulistic episodes. A secondary aim was to detect slow-wave oscillations to examine changes in their amplitude and density prior to behavioral episodes. twenty-two adult sleepwalkers were investigated polysomnographically following 25 h of sleep deprivation. analysis of patients' sleep EEG over the 200 sec prior to the episodes' onset revealed that the episodes were not preceded by a gradual increase in spectral power for either delta or slow delta over frontal, central, or parietal leads. However, time course comparisons revealed significant changes in the density of slow-wave oscillations as well as in very slow oscillations with significant increases occurring during the final 20 sec immediately preceding episode onset. the specificity of these sleep EEG parameters for the occurrence and diagnosis of NREM parasomnias remains to be determined.

  10. 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.

  11. Slow waves in mutually inhibitory neuronal networks

    Science.gov (United States)

    Jalics, Jozsi

    2004-05-01

    A variety of experimental and modeling studies have been performed to investigate wave propagation in networks of thalamic neurons and their relationship to spindle sleep rhythms. It is believed that spindle oscillations result from the reciprocal interaction between thalamocortical (TC) and thalamic reticular (RE) neurons. We consider a network of TC and RE cells reduced to a one-layer network model and represented by a system of singularly perturbed integral-differential equations. Geometric singular perturbation methods are used to prove the existence of a locally unique slow wave pulse that propagates along the network. By seeking a slow pulse solution, we reformulate the problem to finding a heteroclinic orbit in a 3D system of ODEs with two additional constraints on the location of the orbit at two distinct points in time. In proving the persistence of the singular heteroclinic orbit, difficulties arising from the solution passing near points where normal hyperbolicity is lost on a 2D critical manifold are overcome by employing results by Wechselberger [Singularly perturbed folds and canards in R3, Thesis, TU-Wien, 1998].

  12. Application of Planar Broadband Slow-Wave Systems

    Directory of Open Access Journals (Sweden)

    Edvardas Metlevskis

    2012-04-01

    Full Text Available Different types of planar broadband slow-wave systems are used for designing microwave devices. The papers published by Lithuanian scientists analyze and investigate the models of helical and meander slow-wave systems. The article carefully examines the applications of meander slow-wave systems and presents the areas where similar systems, e.g. mobile devices, RFID, wireless technologies are used and reviewed nowadays. The paper also focuses on the examples of the papers discussing antennas, filters and couplers that contain designed and fabricated meander slow-wave systems.Article in Lithuanian

  13. Regional Slow Waves and Spindles in Human Sleep

    Science.gov (United States)

    Nir, Yuval; Staba, Richard J.; Andrillon, Thomas; Vyazovskiy, Vladyslav V.; Cirelli, Chiara; Fried, Itzhak; Tononi, Giulio

    2011-01-01

    SUMMARY The most prominent EEG events in sleep are slow waves, reflecting a slow (waves and the underlying active and inactive neuronal states occur locally. Thus, especially in late sleep, some regions can be active while others are silent. We also find that slow waves can propagate, usually from medial prefrontal cortex to the medial temporal lobe and hippocampus. Sleep spindles, the other hallmark of NREM sleep EEG, are likewise predominantly local. Thus, intracerebral communication during sleep is constrained because slow and spindle oscillations often occur out-of-phase in different brain regions. PMID:21482364

  14. 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.

  15. Involvement of cytokines in slow wave sleep.

    Science.gov (United States)

    Krueger, James M; Clinton, James M; Winters, Bradley D; Zielinski, Mark R; Taishi, Ping; Jewett, Kathryn A; Davis, Christopher J

    2011-01-01

    Cytokines such as tumor necrosis factor alpha (TNFα) and interleukin-1 beta (IL1β) play a role in sleep regulation in health and disease. TNFα or IL1β injection enhances non-rapid eye movement sleep. Inhibition of TNFα or IL1β reduces spontaneous sleep. Mice lacking TNFα or IL1β receptors sleep less. In normal humans and in multiple disease states, plasma levels of TNFα covary with EEG slow wave activity (SWA) and sleep propensity. Many of the symptoms induced by sleep loss, for example, sleepiness, fatigue, poor cognition, enhanced sensitivity to pain, are elicited by injection of exogenous TNFα or IL1β. IL1β or TNFα applied unilaterally to the surface of the cortex induces state-dependent enhancement of EEG SWA ipsilaterally, suggesting greater regional sleep intensity. Interventions such as unilateral somatosensory stimulation enhance localized sleep EEG SWA, blood flow, and somatosensory cortical expression of IL1β and TNFα. State oscillations occur within cortical columns. One such state shares properties with whole animal sleep in that it is dependent on prior cellular activity, shows homeostasis, and is induced by TNFα. Extracellular ATP released during neuro- and gliotransmission enhances cytokine release via purine type 2 receptors. An ATP agonist enhances sleep, while ATP antagonists inhibit sleep. Mice lacking the P2X7 receptor have attenuated sleep rebound responses after sleep loss. TNFα and IL1β alter neuron sensitivity by changing neuromodulator/neurotransmitter receptor expression, allowing the neuron to scale its activity to the presynaptic neurons. TNFα's role in synaptic scaling is well characterized. Because the sensitivity of the postsynaptic neuron is changed, the same input will result in a different network output signal and this is a state change. The top-down paradigm of sleep regulation requires intentional action from sleep/wake regulatory brain circuits to initiate whole-organism sleep. This raises unresolved

  16. Sleep Slow-Wave Activity Regulates Cerebral Glycolytic Metabolism

    OpenAIRE

    Wisor, Jonathan P; Rempe, Michael J; Schmidt, Michelle A.; Moore, Michele E.; Clegern, William C.

    2012-01-01

    Non-rapid eye movement sleep (NREMS) onset is characterized by a reduction in cerebral metabolism and an increase in slow waves, 1–4-Hz oscillations between relatively depolarized and hyperpolarized states in the cerebral cortex. The metabolic consequences of slow-wave activity (SWA) at the cellular level remain uncertain. We sought to determine whether SWA modulates the rate of glycolysis within the cerebral cortex. The real-time measurement of lactate concentration in the mouse cerebral cor...

  17. Damping of Slow Magnetoacoustic Waves in an Inhomogeneous ...

    Indian Academy of Sciences (India)

    Abstract. We study the propagation and dissipation of slow magneto- acoustic waves in an inhomogeneous viscous coronal loop plasma permeated by uniform magnetic field. Only viscosity and thermal con- ductivity are taken into account as dissipative processes in the coronal loop. The damping length of slow-mode ...

  18. Slow waves in locally resonant metamaterials line defect waveguides.

    Science.gov (United States)

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

    2017-11-08

    Many efforts have been devoted to wave slowing, as it is essential, for instance, in analog signal computing and is one prerequisite for increased wave/matter interactions. Despite the interest of many communities, researches have mostly been conducted in optics, where wavelength-scaled structured composite media are promising candidates for compact slow light components. Yet their structural scale prevents them from being transposed to lower frequencies. Here, we propose to overcome this limitation using the deep sub-wavelength scale of locally resonant metamaterials. We experimentally show, in the microwave regime, that introducing coupled resonant defects in such metamaterials creates sub-wavelength waveguides in which wave propagation exhibit reduced group velocities. We qualitatively explain the mechanism underlying this slow wave propagation and demonstrate how it can be used to tune the velocity, achieving group indices as high as 227. We conclude by highlighting the three beneficial consequences of our line defect slow wave waveguides: (1) the sub-wavelength scale making it a compact platform for low frequencies (2) the large group indices that together with the extreme field confinement enables efficient wave/matter interactions and (3) the fact that, contrarily to other approaches, slow wave propagation does not occur at the expense of drastic bandwidth reductions.

  19. Optimizing detection and analysis of slow waves in sleep EEG.

    Science.gov (United States)

    Mensen, Armand; Riedner, Brady; Tononi, Giulio

    2016-12-01

    Analysis of individual slow waves in EEG recording during sleep provides both greater sensitivity and specificity compared to spectral power measures. However, parameters for detection and analysis have not been widely explored and validated. We present a new, open-source, Matlab based, toolbox for the automatic detection and analysis of slow waves; with adjustable parameter settings, as well as manual correction and exploration of the results using a multi-faceted visualization tool. We explore a large search space of parameter settings for slow wave detection and measure their effects on a selection of outcome parameters. Every choice of parameter setting had some effect on at least one outcome parameter. In general, the largest effect sizes were found when choosing the EEG reference, type of canonical waveform, and amplitude thresholding. Previously published methods accurately detect large, global waves but are conservative and miss the detection of smaller amplitude, local slow waves. The toolbox has additional benefits in terms of speed, user-interface, and visualization options to compare and contrast slow waves. The exploration of parameter settings in the toolbox highlights the importance of careful selection of detection METHODS: The sensitivity and specificity of the automated detection can be improved by manually adding or deleting entire waves and or specific channels using the toolbox visualization functions. The toolbox standardizes the detection procedure, sets the stage for reliable results and comparisons and is easy to use without previous programming experience. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Slow wave maturation on a visual working memory task.

    Science.gov (United States)

    Barriga-Paulino, Catarina I; Rodríguez-Martínez, Elena I; Rojas-Benjumea, Ma Ángeles; Gómez, Carlos M

    2014-07-01

    The purpose of the present study is to analyze how the Slow Wave develops in the retention period on a visual Delayed Match-to-Sample task performed by 170 subjects between 6 and 26 years old, divided into 5 age groups. In addition, a neuropsychological test (Working Memory Test Battery for Children) was correlated with this Event Related Potential (ERP) in order to observe possible relationships between Slow Wave maturation and the components of Baddeley and Hitch's Working Memory model. The results showed a slow negativity during the retention period in the posterior region in all the age groups, possibly resulting from sustained neural activity related to the visual item presented. In the anterior region, a positive slow wave was observed in the youngest subjects. Dipole analysis suggests that this fronto-central positivity in children (6-13 years old) consists of the positive side of the posterior negativity, once these subjects only needed two posterior dipoles to explain almost all the neural activity. Negative correlations were shown between the Slow Wave and the Working Memory Test Battery for Children, indicating a commonality in assessing Working Memory with the Slow Wave and the neuropsychological testing. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Characterization of ictal slow waves in epileptic spasms.

    Science.gov (United States)

    Honda, Ryoko; Saito, Yoshiaki; Okumura, Akihisa; Abe, Shinpei; Saito, Takashi; Nakagawa, Eiji; Sugai, Kenji; Sasaki, Masayuki

    2015-12-01

    We characterized the clinico-neurophysiological features of epileptic spasms, particularly focusing on high-voltage slow waves during ictal EEG. We studied 22 patients with epileptic spasms recorded during digital video-scalp EEG, including five individuals who still had persistent spasms after callosotomy. We analysed the duration, amplitude, latency to onset of electromyographic bursts, and distribution of the highest positive and negative peaks of slow waves in 352 spasms. High-voltage positive slow waves preceded the identifiable muscle contractions of spasms. The mean duration of these positive waves was 569±228 m, and the mean latency to electromyographic onset was 182±127 m. These parameters varied markedly even within a patient. The highest peak of the positive component was distributed in variable regions, which was not consistent with the location of lesions on MRI. The peak of the negative component following the positivity was distributed in the neighbouring or opposite areas of the positive peak distribution. No changes were evident in the pre- or post-surgical distributions of the positive peak, or in the interhemispheric delay between both hemispheres, in individuals with callosotomy. Our data imply that ictal positive slow waves are the most common EEG changes during spasms associated with a massive motor component. Plausible explanations for these widespread positive slow waves include the notion that EEG changes possibly reflect involvement of both cortical and subcortical structures.

  2. Characteristics of sleep slow waves in children and adolescents.

    Science.gov (United States)

    Kurth, Salomé; Jenni, Oskar G; Riedner, Brady A; Tononi, Giulio; Carskadon, Mary A; Huber, Reto

    2010-04-01

    Slow waves, a major electrophysiological characteristic of non-rapid eye movement sleep, undergo prominent changes across puberty. This study provides a detailed description of sleep slow waves of prepubertal children and mature adolescents to better understand the mechanisms underlying the decrease of activity in the slow-wave frequency range across puberty. All-night sleep electroencephalographic recordings were performed for baseline and after sleep deprivation. N/A. Eight prepubertal children (Tanner 1/2, 11.9 +/- 0.8 years, 3 boys) and 6 mature adolescents (Tanner 4/5, 14.3 +/- 1.4 years, 3 boys). Thirty-six hours of sleep deprivation. Both during baseline and after sleep deprivation, a steeper slope of slow waves was observed in prepubertal children (351.0 +/- 49.5 microV/s), compared with mature adolescents (215.0 +/- 27.2 microV/s, P<0.05; mean of first 5 NREM sleep episodes from baseline), even accounting for overall amplitude differences. Based on a recent thalamocortical computer model, these findings may indicate a greater synaptic strength of neurons involved in the generation of sleep slow waves in prepubertal children, compared with mature adolescents. Such increased synaptic strength may be due to greater density or greater efficacy of cortical synapses or both.

  3. Progress in Mathematical Modeling of Gastrointestinal Slow Wave Abnormalities.

    Science.gov (United States)

    Du, Peng; Calder, Stefan; Angeli, Timothy R; Sathar, Shameer; Paskaranandavadivel, Niranchan; O'Grady, Gregory; Cheng, Leo K

    2017-01-01

    Gastrointestinal (GI) motility is regulated in part by electrophysiological events called slow waves, which are generated by the interstitial cells of Cajal (ICC). Slow waves propagate by a process of "entrainment," which occurs over a decreasing gradient of intrinsic frequencies in the antegrade direction across much of the GI tract. Abnormal initiation and conduction of slow waves have been demonstrated in, and linked to, a number of GI motility disorders. A range of mathematical models have been developed to study abnormal slow waves and applied to propose novel methods for non-invasive detection and therapy. This review provides a general outline of GI slow wave abnormalities and their recent classification using multi-electrode (high-resolution) mapping methods, with a particular emphasis on the spatial patterns of these abnormal activities. The recently-developed mathematical models are introduced in order of their biophysical scale from cellular to whole-organ levels. The modeling techniques, main findings from the simulations, and potential future directions arising from notable studies are discussed.

  4. Characteristics of Sleep Slow Waves in Children and Adolescents

    Science.gov (United States)

    Kurth, Salomé; Jenni, Oskar G.; Riedner, Brady A.; Tononi, Giulio; Carskadon, Mary A.; Huber, Reto

    2010-01-01

    Study Objectives: Slow waves, a major electrophysiological characteristic of non-rapid eye movement sleep, undergo prominent changes across puberty. This study provides a detailed description of sleep slow waves of prepubertal children and mature adolescents to better understand the mechanisms underlying the decrease of activity in the slow-wave frequency range across puberty. Design: All-night sleep electroencephalographic recordings were performed for baseline and after sleep deprivation. Setting: N/A. Participants: Eight prepubertal children (Tanner 1/2, 11.9 ± 0.8 years, 3 boys) and 6 mature adolescents (Tanner 4/5, 14.3 ± 1.4 years, 3 boys). Interventions: Thirty-six hours of sleep deprivation. Measurements and Results: Both during baseline and after sleep deprivation, a steeper slope of slow waves was observed in prepubertal children (351.0 ± 49.5 μV/s), compared with mature adolescents (215.0 ± 27.2 μV/s, P sleep episodes from baseline), even accounting for overall amplitude differences. Conclusions: Based on a recent thalamocortical computer model, these findings may indicate a greater synaptic strength of neurons involved in the generation of sleep slow waves in prepubertal children, compared with mature adolescents. Such increased synaptic strength may be due to greater density or greater efficacy of cortical synapses or both. Citation: Kurth S; Jenni OG; Riedner BA; Tononi G; Carskadon MA; Huber R. Characteristics of sleep slow waves in children and adolescents. SLEEP 2010;33(4):475-480. PMID:20394316

  5. Slow Drift-Oscillations of a Ship in Irregular Waves

    Directory of Open Access Journals (Sweden)

    Odd M. Faltinsen

    1980-10-01

    Full Text Available A procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented. The hydrodynamic boundary-value problem is solved correctly to second order in wave amplitude. Results in the form of second order transfer functions are presented for different, two-dimensional shapes. It is concluded that Newman's approximative method is a practical way to calculate slow drift excitation forces on a ship in beam sea and it is suggested that it may be used in a more general case. Applications of the results for moored ships are discussed.

  6. 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

  7. 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 electromag...

  8. Sleep slow-wave activity regulates cerebral glycolytic metabolism.

    Science.gov (United States)

    Wisor, Jonathan P; Rempe, Michael J; Schmidt, Michelle A; Moore, Michele E; Clegern, William C

    2013-08-01

    Non-rapid eye movement sleep (NREMS) onset is characterized by a reduction in cerebral metabolism and an increase in slow waves, 1-4-Hz oscillations between relatively depolarized and hyperpolarized states in the cerebral cortex. The metabolic consequences of slow-wave activity (SWA) at the cellular level remain uncertain. We sought to determine whether SWA modulates the rate of glycolysis within the cerebral cortex. The real-time measurement of lactate concentration in the mouse cerebral cortex demonstrates that it increases during enforced wakefulness. In spontaneous sleep/wake cycles, lactate concentration builds during wakefulness and rapid eye movement sleep and declines during NREMS. The rate at which lactate concentration declines during NREMS is proportional to the magnitude of electroencephalographic (EEG) activity at frequencies of cerebral SWA promotes a decline in the rate of glycolysis in the cerebral cortex. These results demonstrate a cellular energetic function for sleep SWA, which may contribute to its restorative effects on brain function.

  9. Cortistatin promotes and negatively correlates with slow-wave sleep.

    Science.gov (United States)

    Bourgin, Patrice; Fabre, Véronique; Huitrón-Reséndiz, Salvador; Henriksen, Steven J; Prospero-Garcia, Oscar; Criado, José R; de Lecea, Luis

    2007-08-01

    Sleep need is characterized by the level of slow-wave activity (SWA) and increases with time spent awake. The molecular nature of this sleep homeostatic process is practically unknown. Here, we show that intracerebroventricular administration of the neuropeptide, cortistatin (CST-14), enhances EEG synchronization by selectively promoting deep slow-wave sleep (SWS) during both the light and dark period in rats. CST-14 also increases the level of slow-wave activity (SWA) within deep SWS during the first two hours following CST-14 administration. Steady-state levels of preprocortistatin mRNA oscillate during the light:dark cycle and are four-fold higher upon total 24-h sleep deprivation, returning progressively to normal levels after eight hours of sleep recovery. Preprocortistatin mRNA is expressed upon sleep deprivation in a particular subset of cortical interneurons that colocalize with c-fos. In contrast, the number of CST-positive cells coexpressing pERK1/2 decreases under sleep deprivation. The capacity of CST-14 to increase SWA, together with preprocortistatin's inverse correlation with time spent in SWS, suggests a potential role in sleep homeostatic processes.

  10. Spontaneous K-Complex Density in Slow-Wave Sleep.

    Science.gov (United States)

    Manzar, Md Dilshad; Rajput, Mohammad Muntafa; Zannat, Wassilatul; Pandi-Perumal, Seithikurippu R; BaHammam, Ahmed S; Hussain, M Ejaz

    2016-01-01

    To study spontaneous K-complex (KC) densities during slow-wave sleep. The secondary objective was to estimate intra-non-rapid eye movement (NREM) sleep differences in KC density. It is a retrospective study using EEG data included in polysomnographic records from the archive at the sleep research laboratory of the Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, India. The EEG records of 4459 minutes were used. The study presents a manual identification investigation of KCs in 17 healthy young adult male volunteers (age = 23.82±3.40 years and BMI = 23.42±4.18 kg/m2). N3 had a higher KC density than N2 (Z = -2.485, p = 0.013) for all of the probes taken together. Four EEG probes had a higher probe-specific KC density during N3. The inter-probe KC density differed significantly during N2 (χ2 = 67.91, p theory of KC generation. The significantly higher KC density during N3 may imply that the neuro-anatomical origin of slow-wave activity and KC is the same. This temporal alignment with slow-wave activity supports the sleep-promoting function of the KC.

  11. Spontaneous K-Complex Density in Slow-Wave Sleep.

    Directory of Open Access Journals (Sweden)

    Md Dilshad Manzar

    Full Text Available To study spontaneous K-complex (KC densities during slow-wave sleep. The secondary objective was to estimate intra-non-rapid eye movement (NREM sleep differences in KC density.It is a retrospective study using EEG data included in polysomnographic records from the archive at the sleep research laboratory of the Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, India. The EEG records of 4459 minutes were used. The study presents a manual identification investigation of KCs in 17 healthy young adult male volunteers (age = 23.82±3.40 years and BMI = 23.42±4.18 kg/m2.N3 had a higher KC density than N2 (Z = -2.485, p = 0.013 for all of the probes taken together. Four EEG probes had a higher probe-specific KC density during N3. The inter-probe KC density differed significantly during N2 (χ2 = 67.91, p < .001, N3 (χ2 = 70.62, p < .001 and NREM (χ2 = 68.50, p < .001. The percent distribution of KC decreased uniformly with sleep cycles.The inter-probe differences during N3 establish the fronto-central dominance of the KC density regardless of sleep stage. This finding supports one local theory of KC generation. The significantly higher KC density during N3 may imply that the neuro-anatomical origin of slow-wave activity and KC is the same. This temporal alignment with slow-wave activity supports the sleep-promoting function of the KC.

  12. Propagated infra-slow intrinsic brain activity reorganizes across wake and slow wave sleep.

    Science.gov (United States)

    Mitra, Anish; Snyder, Abraham Z; Tagliazucchi, Enzo; Laufs, Helmut; Raichle, Marcus E

    2015-11-09

    Propagation of slow intrinsic brain activity has been widely observed in electrophysiogical studies of slow wave sleep (SWS). However, in human resting state fMRI (rs-fMRI), intrinsic activity has been understood predominantly in terms of zero-lag temporal synchrony (functional connectivity) within systems known as resting state networks (RSNs). Prior rs-fMRI studies have found that RSNs are generally preserved across wake and sleep. Here, we use a recently developed analysis technique to study propagation of infra-slow intrinsic blood oxygen level dependent (BOLD) signals in normal adults during wake and SWS. This analysis reveals marked changes in propagation patterns in SWS vs. wake. Broadly, ordered propagation is preserved within traditionally defined RSNs but lost between RSNs. Additionally, propagation between cerebral cortex and subcortical structures reverses directions, and intra-cortical propagation becomes reorganized, especially in visual and sensorimotor cortices. These findings show that propagated rs-fMRI activity informs theoretical accounts of the neural functions of sleep.

  13. 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.

  14. Analysis of Rectangular Folded-Waveguide Millimeter-Wave Slow-wave Structures using Conformal Transformations

    Science.gov (United States)

    Sumathy, M.; Vinoy, K. J.; Datta, S. K.

    2009-03-01

    An analysis of rectangular folded-waveguide slow-wave structure was developed using conformal mapping technique through Schwarz’s polygon transformation and closed form expressions for the lumped capacitance and inductance per period of the slow-wave structure were derived in terms of the physical dimensions of the structure, incorporating the effects of the beam hole in the lumped parameters. The lumped parameters were subsequently interpreted for obtaining the dispersion and interaction impedance characteristics of the structure. The analysis was benchmarked for two typical millimeter-wave structures, one operating in Ka-band and the other operating in Q-band, against measurement and 3D electromagnetic modeling using MAFIA.

  15. Dynamic coupling between slow waves and sleep spindles during slow wave sleep in humans is modulated by functional pre-sleep activation.

    Science.gov (United States)

    Yordanova, Juliana; Kirov, Roumen; Verleger, Rolf; Kolev, Vasil

    2017-11-03

    Co-existent sleep spindles and slow waves have been viewed as a mechanism for offline information processing. Here we explored if the temporal synchronization between slow waves and spindle activity during slow wave sleep (SWS) in humans was modulated by preceding functional activations during pre-sleep learning. We activated differentially the left and right hemisphere before sleep by using a lateralized variant of serial response time task (SRTT) and verified these inter-hemispheric differences by analysing alpha and beta electroencephalographic (EEG) activities during learning. The stability and timing of coupling between positive and negative phases of slow waves and sleep spindle activity during SWS were quantified. Spindle activity was temporally synchronized with both positive (up-state) and negative (down-state) slow half waves. Synchronization of only the fast spindle activity was laterally asymmetric after learning, corresponding to hemisphere-specific activations before sleep. However, the down state was associated with decoupling, whereas the up-state was associated with increased coupling of fast spindle activity over the pre-activated hemisphere. These observations provide original evidence that (1) the temporal grouping of fast spindles by slow waves is a dynamic property of human SWS modulated by functional pre-sleep activation patterns, and (2) fast spindles synchronized by slow waves are functionally distinct.

  16. Blindfolding during wakefulness causes decrease in sleep slow wave activity.

    Science.gov (United States)

    Korf, Eva Magdalena; Mölle, Matthias; Born, Jan; Ngo, Hong-Viet V

    2017-04-01

    Slow wave activity (SWA, 0.5-4 Hz) represents the predominant EEG oscillatory activity during slow wave sleep (SWS). Its amplitude is considered in part a reflection of synaptic potentiation in cortical networks due to encoding of information during prior waking, with higher amplitude indicating stronger potentiation. Previous studies showed that increasing and diminishing specific motor behaviors produced corresponding changes in SWA in the respective motor cortical areas during subsequent SWS Here, we tested whether this relationship can be generalized to the visual system, that is, whether diminishing encoding of visual information likewise leads to a localized decrease in SWA over the visual cortex. Experiments were performed in healthy men whose eyes on two different days were or were not covered for 10.5 h before bedtime. The subject's EEG was recorded during sleep and, after sleep, visual evoked potentials (VEPs) were recorded. SWA during nonrapid eye movement sleep (NonREM sleep) was lower after blindfolding than after eyes open (P < 0.01). The decrease in SWA that was most consistent during the first 20 min of NonREM sleep, did not remain restricted to visual cortex regions, with changes over frontal and parietal cortical regions being even more pronounced. In the morning after sleep, the N75-P100 peak-to-peak-amplitude of the VEP was significantly diminished in the blindfolded condition. Our findings confirm a link between reduced wake encoding and diminished SWA during ensuing NonREM sleep, although this link appears not to be restricted to sensory cortical areas. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  17. Circadian regulation of slow waves in human sleep: Topographical aspects

    Science.gov (United States)

    Lazar, Alpar S.; Lazar, Zsolt I.; Dijk, Derk-Jan

    2015-01-01

    Slow waves (SWs, 0.5–4 Hz) in field potentials during sleep reflect synchronized alternations between bursts of action potentials and periods of membrane hyperpolarization of cortical neurons. SWs decline during sleep and this is thought to be related to a reduction of synaptic strength in cortical networks and to be central to sleep's role in maintaining brain function. A central assumption in current concepts of sleep function is that SWs during sleep, and associated recovery processes, are independent of circadian rhythmicity. We tested this hypothesis by quantifying all SWs from 12 EEG derivations in 34 participants in whom 231 sleep periods were scheduled across the circadian cycle in a 10-day forced-desynchrony protocol which allowed estimation of the separate circadian and sleep-dependent modulation of SWs. Circadian rhythmicity significantly modulated the incidence, amplitude, frequency and the slope of the SWs such that the peaks of the circadian rhythms in these slow-wave parameters were located during the biological day. Topographical analyses demonstrated that the sleep-dependent modulation of SW characteristics was most prominent in frontal brain areas whereas the circadian effect was similar to or greater than the sleep-dependent modulation over the central and posterior brain regions. The data demonstrate that circadian rhythmicity directly modulates characteristics of SWs thought to be related to synaptic plasticity and that this modulation depends on topography. These findings have implications for the understanding of local sleep regulation and conditions such as ageing, depression, and neurodegeneration which are associated with changes in SWs, neural plasticity and circadian rhythmicity. PMID:25979664

  18. Vocabulary learning benefits from REM after slow-wave sleep.

    Science.gov (United States)

    Batterink, Laura J; Westerberg, Carmen E; Paller, Ken A

    2017-10-01

    Memory reactivation during slow-wave sleep (SWS) influences the consolidation of recently acquired knowledge. This reactivation occurs spontaneously during sleep but can also be triggered by presenting learning-related cues, a technique known as targeted memory reactivation (TMR). Here we examined whether TMR can improve vocabulary learning. Participants learned the meanings of 60 novel words. Auditory cues for half the words were subsequently presented during SWS in an afternoon nap. Memory performance for cued versus uncued words did not differ at the group level but was systematically influenced by REM sleep duration. Participants who obtained relatively greater amounts of REM showed a significant benefit for cued relative to uncued words, whereas participants who obtained little or no REM demonstrated a significant effect in the opposite direction. We propose that REM after SWS may be critical for the consolidation of highly integrative memories, such as new vocabulary. Reactivation during SWS may allow newly encoded memories to be associated with other information, but this association can include disruptive linkages with pre-existing memories. Subsequent REM sleep may then be particularly beneficial for integrating new memories into appropriate pre-existing memory networks. These findings support the general proposition that memory storage benefits optimally from a cyclic succession of SWS and REM. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Mechanisms of Memory Retrieval in Slow-Wave Sleep.

    Science.gov (United States)

    Cairney, Scott A; Sobczak, Justyna M; Lindsay, Shane; Gaskell, M Gareth

    2017-09-01

    Memories are strengthened during sleep. The benefits of sleep for memory can be enhanced by re-exposing the sleeping brain to auditory cues; a technique known as targeted memory reactivation (TMR). Prior studies have not assessed the nature of the retrieval mechanisms underpinning TMR: the matching process between auditory stimuli encountered during sleep and previously encoded memories. We carried out two experiments to address this issue. In Experiment 1, participants associated words with verbal and nonverbal auditory stimuli before an overnight interval in which subsets of these stimuli were replayed in slow-wave sleep. We repeated this paradigm in Experiment 2 with the single difference that the gender of the verbal auditory stimuli was switched between learning and sleep. In Experiment 1, forgetting of cued (vs. noncued) associations was reduced by TMR with verbal and nonverbal cues to similar extents. In Experiment 2, TMR with identical nonverbal cues reduced forgetting of cued (vs. noncued) associations, replicating Experiment 1. However, TMR with nonidentical verbal cues reduced forgetting of both cued and noncued associations. These experiments suggest that the memory effects of TMR are influenced by the acoustic overlap between stimuli delivered at training and sleep. Our findings hint at the existence of two processing routes for memory retrieval during sleep. Whereas TMR with acoustically identical cues may reactivate individual associations via simple episodic matching, TMR with nonidentical verbal cues may utilize linguistic decoding mechanisms, resulting in widespread reactivation across a broad category of memories.

  20. Effects of aging on slow-wave sleep dynamics and human spatial navigational memory consolidation.

    Science.gov (United States)

    Varga, Andrew W; Ducca, Emma L; Kishi, Akifumi; Fischer, Esther; Parekh, Ankit; Koushyk, Viachaslau; Yau, Po Lai; Gumb, Tyler; Leibert, David P; Wohlleber, Margaret E; Burschtin, Omar E; Convit, Antonio; Rapoport, David M; Osorio, Ricardo S; Ayappa, Indu

    2016-06-01

    The consolidation of spatial navigational memory during sleep is supported by electrophysiological and behavioral evidence. The features of sleep that mediate this ability may change with aging, as percentage of slow-wave sleep is canonically thought to decrease with age, and slow waves are thought to help orchestrate hippocampal-neocortical dialog that supports systems level consolidation. In this study, groups of younger and older subjects performed timed trials before and after polysomnographically recorded sleep on a 3D spatial maze navigational task. Although younger subjects performed better than older subjects at baseline, both groups showed similar improvement across presleep trials. However, younger subjects experienced significant improvement in maze performance during sleep that was not observed in older subjects, without differences in morning psychomotor vigilance between groups. Older subjects had sleep quality marked by decreased amount of slow-wave sleep and increased fragmentation of slow-wave sleep, resulting in decreased slow-wave activity. Across all subjects, frontal slow-wave activity was positively correlated with both overnight change in maze performance and medial prefrontal cortical volume, illuminating a potential neuroanatomical substrate for slow-wave activity changes with aging and underscoring the importance of slow-wave activity in sleep-dependent spatial navigational memory consolidation. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Numerical investigation of reflection properties of fast and slow longitudinal waves in cancellous bone.

    Science.gov (United States)

    Hosokawa, Atsushi

    2013-05-01

    The basic reflection properties of fast and slow waves propagating in cancellous bone were numerically investigated using finite-difference time-domain (FDTD) simulations with 18 microcomputed tomographic (µCT) models of bovine cancellous bone. The simulated results showed that both reflection coefficients of the fast and slow waves linearly increased with porosity.

  2. EEG slow waves in traumatic brain injury: Convergent findings in mouse and man

    Directory of Open Access Journals (Sweden)

    Mo H. Modarres

    2017-01-01

    Conclusion and implications: Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.

  3. Covert reorganization of implicit task representations by slow wave sleep.

    Directory of Open Access Journals (Sweden)

    Juliana Yordanova

    Full Text Available BACKGROUND: There is evidence that slow wave sleep (SWS promotes the consolidation of memories that are subserved by mediotemporal- and hippocampo-cortical neural networks. In contrast to implicit memories, explicit memories are accompanied by conscious (attentive and controlled processing. Awareness at pre-sleep encoding has been recognized as critical for the off-line memory consolidation. The present study elucidated the role of task-dependent cortical activation guided by attentional control at pre-sleep encoding for the consolidation of hippocampus-dependent memories during sleep. METHODOLOGY: A task with a hidden regularity was used (Number Reduction Task, NRT, in which the responses that can be implicitly predicted by the hidden regularity activate hippocampo-cortical networks more strongly than responses that cannot be predicted. Task performance was evaluated before and after early-night sleep, rich in SWS, and late-night sleep, rich in rapid eye movement (REM sleep. In implicit conditions, slow cortical potentials (SPs were analyzed to reflect the amount of controlled processing and the localization of activated neural task representations. PRINCIPAL FINDINGS: During implicit learning before sleep, the amount of controlled processing did not differ between unpredictable and predictable responses, nor between early- and late-night sleep groups. A topographic re-distribution of SPs indicating a spatial reorganization occurred only after early, not after late sleep, and only for predictable responses. These SP changes correlated with the amount of SWS and were covert because off-line RT decrease did not differentiate response types or sleep groups. CONCLUSIONS: It is concluded that SWS promotes the neural reorganization of task representations that rely on the hippocampal system despite absence of conscious access to these representations. SIGNIFICANCE: Original neurophysiologic evidence is provided for the role of SWS in the

  4. Identification of slow magnetosonic wave trains and their evolution in 3-D compressible turbulence simulation

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2015-01-01

    Full Text Available In solar wind, dissipation of slow-mode magnetosonic waves may play a significant role in heating the solar wind, and these modes contribute essentially to the solar wind compressible turbulence. Most previous identifications of slow waves utilized the characteristic negative correlation between δ|B| and δρ. However, that criterion does not well identify quasi-parallel slow waves, for which δ|B| is negligible compared to δρ. Here we present a new method of identification, which will be used in 3-D compressible simulation. It is based on two criteria: (1 that VpB0 (phase speed projected along B0 is around ± cs, and that (2 there exists a clear correlation of δv|| and δρ. Our research demonstrates that if vA > cs, slow waves possess correlation between δv|| and δρ, with δρ / δv|| ≈ ± ρ0 / cs. This method helps us to distinguish slow-mode waves from fast and Alfvén waves, both of which do not have this polarity relation. The criteria are insensitive to the propagation angle θk B, defined as the angle between wave vector k and B0; they can be applied with a wide range of β if only vA > cs. In our numerical simulation, we have identified four cases of slow wave trains with this method. The slow wave trains seem to deform, probably caused by interaction with other waves; as a result, fast or Alfvén waves may be produced during the interaction and seem to propagate bidirectionally away. Our identification and analysis of the wave trains provide useful methods for investigations of compressible turbulence in the solar wind or in similar environments, and will thus deepen understandings of slow waves in the turbulence.

  5. EEG slow waves in traumatic brain injury: Convergent findings in mouse and man.

    Science.gov (United States)

    Modarres, Mo; Kuzma, Nicholas N; Kretzmer, Tracy; Pack, Allan I; Lim, Miranda M

    2016-07-01

    Evidence from previous studies suggests that greater sleep pressure, in the form of EEG-based slow waves, accumulates in specific brain regions that are more active during prior waking experience. We sought to quantify the number and coherence of EEG slow waves in subjects with mild traumatic brain injury (mTBI). We developed a method to automatically detect individual slow waves in each EEG channel, and validated this method using simulated EEG data. We then used this method to quantify EEG-based slow waves during sleep and wake states in both mouse and human subjects with mTBI. A modified coherence index that accounts for information from multiple channels was calculated as a measure of slow wave synchrony. Brain-injured mice showed significantly higher theta:alpha amplitude ratios and significantly more slow waves during spontaneous wakefulness and during prolonged sleep deprivation, compared to sham-injured control mice. Human subjects with mTBI showed significantly higher theta:beta amplitude ratios and significantly more EEG slow waves while awake compared to age-matched control subjects. We then quantified the global coherence index of slow waves across several EEG channels in human subjects. Individuals with mTBI showed significantly less EEG global coherence compared to control subjects while awake, but not during sleep. EEG global coherence was significantly correlated with severity of post-concussive symptoms (as assessed by the Neurobehavioral Symptom Inventory scale). Taken together, our data from both mouse and human studies suggest that EEG slow wave quantity and the global coherence index of slow waves may represent a sensitive marker for the diagnosis and prognosis of mTBI and post-concussive symptoms.

  6. 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. © 2013 European Sleep Research Society.

  7. Detecting slow wave sleep using a single EEG signal channel.

    Science.gov (United States)

    Su, Bo-Lin; Luo, Yuxi; Hong, Chih-Yuan; Nagurka, Mark L; Yen, Chen-Wen

    2015-03-30

    In addition to the cost and complexity of processing multiple signal channels, manual sleep staging is also tedious, time consuming, and error-prone. The aim of this paper is to propose an automatic slow wave sleep (SWS) detection method that uses only one channel of the electroencephalography (EEG) signal. The proposed approach distinguishes itself from previous automatic sleep staging methods by using three specially designed feature groups. The first feature group characterizes the waveform pattern of the EEG signal. The remaining two feature groups are developed to resolve the difficulties caused by interpersonal EEG signal differences. The proposed approach was tested with 1,003 subjects, and the SWS detection results show kappa coefficient at 0.66, an accuracy level of 0.973, a sensitivity score of 0.644 and a positive predictive value of 0.709. By excluding sleep apnea patients and persons whose age is older than 55, the SWS detection results improved to kappa coefficient, 0.76; accuracy, 0.963; sensitivity, 0.758; and positive predictive value, 0.812. With newly developed signal features, this study proposed and tested a single-channel EEG-based SWS detection method. The effectiveness of the proposed approach was demonstrated by applying it to detect the SWS of 1003 subjects. Our test results show that a low SWS ratio and sleep apnea can degrade the performance of SWS detection. The results also show that a large and accurately staged sleep dataset is of great importance when developing automatic sleep staging methods. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. 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 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 stimuli.

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

    Directory of Open Access Journals (Sweden)

    Ana Maria Lemos Nogueira

    2015-07-01

    Full Text Available 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 (controlslow 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

  10. Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves.

    Science.gov (United States)

    Frauscher, Birgit; von Ellenrieder, Nicolás; Ferrari-Marinho, Taissa; Avoli, Massimo; Dubeau, François; Gotman, Jean

    2015-06-01

    Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated ('down', hyperpolarized) and an activated state ('up', depolarized). The 'up' state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the 'up' state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ∼ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the 'up' and 'down' states. Spike and high frequency oscillation density was highest during the transition from the 'up' to the 'down' state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the 'down' to the 'up' state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow waves that are frequent, but not

  11. Facilitation of epileptic activity during sleep is mediated by high amplitude slow waves

    Science.gov (United States)

    von Ellenrieder, Nicolás; Ferrari-Marinho, Taissa; Avoli, Massimo; Dubeau, François; Gotman, Jean

    2015-01-01

    Epileptic discharges in focal epilepsy are frequently activated during non-rapid eye movement sleep. Sleep slow waves are present during this stage and have been shown to include a deactivated (‘down’, hyperpolarized) and an activated state (‘up’, depolarized). The ‘up’ state enhances physiological rhythms, and we hypothesize that sleep slow waves and particularly the ‘up’ state are the specific components of non-rapid eye movement sleep that mediate the activation of epileptic activity. We investigated eight patients with pharmaco-resistant focal epilepsies who underwent combined scalp-intracerebral electroencephalography for diagnostic evaluation. We analysed 259 frontal electroencephalographic channels, and manually marked 442 epileptic spikes and 8487 high frequency oscillations during high amplitude widespread slow waves, and during matched control segments with low amplitude widespread slow waves, non-widespread slow waves or no slow waves selected during the same sleep stages (total duration of slow wave and control segments: 49 min each). During the slow waves, spikes and high frequency oscillations were more frequent than during control segments (79% of spikes during slow waves and 65% of high frequency oscillations, both P ∼ 0). The spike and high frequency oscillation density also increased for higher amplitude slow waves. We compared the density of spikes and high frequency oscillations between the ‘up’ and ‘down’ states. Spike and high frequency oscillation density was highest during the transition from the ‘up’ to the ‘down’ state. Interestingly, high frequency oscillations in channels with normal activity expressed a different peak at the transition from the ‘down’ to the ‘up’ state. These results show that the apparent activation of epileptic discharges by non-rapid eye movement sleep is not a state-dependent phenomenon but is predominantly associated with specific events, the high amplitude widespread slow

  12. The occurrence of individual slow waves in sleep is predicted by heart rate.

    Science.gov (United States)

    Mensen, Armand; Zhang, Zhongxing; Qi, Ming; Khatami, Ramin

    2016-07-22

    The integration of near-infrared spectroscopy and electroencephalography measures presents an ideal method to study the haemodynamics of sleep. While the cortical dynamics and neuro-modulating influences affecting the transition from wakefulness to sleep is well researched, the assumption has been that individual slow waves, the hallmark of deep sleep, are spontaneously occurring cortical events. By creating event-related potentials from the NIRS recording, time-locked to the onset of thousands of individual slow waves, we show the onset of slow waves is phase-locked to an ongoing oscillation in the NIRS recording. This oscillation stems from the moment to moment fluctuations of light absorption caused by arterial pulsations driven by the heart beat. The same oscillating signal can be detected if the electrocardiogram is time-locked to the onset of the slow wave. The ongoing NIRS oscillation suggests that individual slow wave initiation is dependent on that signal, and not the other way round. However, the precise causal links remain speculative. We propose several potential mechanisms: that the heart-beat or arterial pulsation acts as a stimulus which evokes a down-state; local fluctuations in energy supply may lead to a network effect of hyperpolarization; that the arterial pulsations lead to corresponding changes in the cerebral-spinal-fluid which evokes the slow wave; or that a third neural generator, regulating heart rate and slow waves may be involved.

  13. Long period slow MHD waves in the solar wind source region

    OpenAIRE

    Dwivedi, B. N.; Srivastava, A. K.

    2006-01-01

    We consider compressive viscosity and thermal conductivity to study the propagation and dissipation of long period slow longitudinal MHD waves in polar coronal holes. We discuss their likely role in the line profile narrowing, and in the energy budget for coronal holes and the solar wind. We compare the contribution of longitudinal MHD waves with high frequency Alfven waves.

  14. Developmental aspects of sleep slow waves: linking sleep, brain maturation and behavior.

    Science.gov (United States)

    Ringli, Maya; Huber, Reto

    2011-01-01

    Sleep slow waves are the major electrophysiological features of non-rapid eye movement (NREM) sleep. Although there is growing understanding of where slow waves originate and how they are generated during sleep, the function of slow waves is still largely unclear. A recently proposed hypothesis relates slow waves to the homeostatic regulation of synaptic plasticity. While several studies confirm a correlation between experimentally triggered synaptic changes and slow-wave activity (SWA), little is known about its association to synaptic changes occurring during cortical maturation. Interestingly, slow waves undergo remarkable changes during development that parallel the time course of cortical maturation. In a recent cross-sectional study including children and adolescents, the topographical distribution of SWA was analyzed with high-density electroencephalography. The results showed age-dependent differences in SWA topography: SWA was highest over posterior regions during early childhood and then shifted over central derivations to the frontal cortex in late adolescence. This trajectory of SWA topography matches the course of cortical gray maturation. In this chapter, the major changes in slow waves during development are highlighted and linked to cortical maturation and behavior. Interestingly, synaptic density and slow-wave amplitude increase during childhood are highest shortly before puberty, decline thereafter during adolescence, reaching overall stable levels during adulthood. The question arises whether SWA is merely reflecting cortical changes or if it plays an active role in brain maturation. We thereby propose a model, by which sleep slow waves may contribute to cortical maturation. We hypothesize that while there is a balance between synaptic strengthening and synaptic downscaling in adults, the balance of strengthening/formation and weakening/elimination is tilted during development. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Electrical slow waves in the mouse oviduct are dependent on extracellular and intracellular calcium sources

    Science.gov (United States)

    Dixon, Rose Ellen; Britton, Fiona C.; Baker, Salah A.; Hennig, Grant W.; Rollings, Christina M.; Sanders, Kenton M.

    2011-01-01

    Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca2+ imaging were performed to examine the role of extracellular and intracellular Ca2+ sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca2+ channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca2+ concentration ([Ca2+]o) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca2+ waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca2+]o. Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K+ concentration ([K+]o). Ni2+ also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca2+ waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional SERCA pumps. PMID:21881003

  16. Electrical slow waves in the mouse oviduct are dependent on extracellular and intracellular calcium sources.

    Science.gov (United States)

    Dixon, Rose Ellen; Britton, Fiona C; Baker, Salah A; Hennig, Grant W; Rollings, Christina M; Sanders, Kenton M; Ward, Sean M

    2011-12-01

    Spontaneous contractions of the myosalpinx are critical for oocyte transport along the oviduct. Slow waves, the electrical events that underlie myosalpinx contractions, are generated by a specialized network of pacemaker cells called oviduct interstitial cells of Cajal (ICC-OVI). The ionic basis of oviduct pacemaker activity is unknown. Intracellular recordings and Ca(2+) imaging were performed to examine the role of extracellular and intracellular Ca(2+) sources in slow wave generation. RT-PCR was performed to determine the transcriptional expression of Ca(2+) channels. Molecular studies revealed most isoforms of L- and T-type calcium channels (Cav1.2,1.3,1.4,3.1,3.2,3.3) were expressed in myosalpinx. Reduction of extracellular Ca(2+) concentration ([Ca(2+)](o)) resulted in the abolition of slow waves and myosalpinx contractions without significantly affecting resting membrane potential (RMP). Spontaneous Ca(2+) waves spread through ICC-OVI cells at a similar frequency to slow waves and were inhibited by reduced [Ca(2+)](o). Nifedipine depolarized RMP and inhibited slow waves; however, pacemaker activity returned when the membrane was repolarized with reduced extracellular K(+) concentration ([K(+)](o)). Ni(2+) also depolarized RMP but failed to block slow waves. The importance of ryanodine and inositol 1,4,5 trisphosphate-sensitive stores were examined using ryanodine, tetracaine, caffeine, and 2-aminoethyl diphenylborinate. Results suggest that although both stores are involved in regulation of slow wave frequency, neither are exclusively essential. The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) pump inhibitor cyclopiazonic acid inhibited pacemaker activity and Ca(2+) waves suggesting that a functional SERCA pump is necessary for pacemaker activity. In conclusion, results from this study suggest that slow wave generation in the oviduct is voltage dependent, occurs in a membrane potential window, and is dependent on extracellular calcium and functional

  17. Influence Coefficients of Constructive Parameters of Meander Slow-Wave System with Additional Shields

    Directory of Open Access Journals (Sweden)

    Metlevskis Edvardas

    2016-12-01

    Full Text Available Constructions of meander slow-wave systems with additional shields grounded at different positions are presented. The construction of meander slow-wave systems with additional shields grounded at both edges is investigated in detail. The influence of the main constructive parameters on the electrical characteristics of meander slow-wave systems with additional shields grounded at both edges is evaluated. The main constructive parameters of the investigated system are: the length of the conductor, the width of meander conductor, the width of additional shield, and the width of the gap between adjacent meander conductors.

  18. 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.

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

    NARCIS (Netherlands)

    Astill, R.G.; Piantoni, G.; Raymann, R.J.E.M; Vis, J.C.; Coppens, J.E.; Walker, M.P.; Stickgold, R.; van der Werf, Y.D.; van Someren, E.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.

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

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Krozer, Viktor; Kotiranta, Mikko

    2011-01-01

    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...

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

    Science.gov (United States)

    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 and an association of interindividual differences in skill and sleep characteristics. Methods: 30 children (19 females, 10.7 ± 0.8 years of age; mean ± SD) performed finger sequence tapping tasks in a repeated-measures design spanning 4 days including 1 polysomnography (PSG) night. Initial and delayed performance were assessed over 12 h of wake; 12 h with sleep; and 24 h with wake and sleep. For the 12 h with sleep, children were assigned to one of three conditions: modulation of slow waves and spindles was attempted using acoustic perturbation, and compared to yoked and no-sound control conditions. Analyses: Mixed effect regression models evaluated the association of sleep, its macrostructure and spindles and slow wave parameters with initial and delayed speed and accuracy. Results and Conclusions: Children enhance their accuracy only over an interval with sleep. Unlike previously reported in adults, children enhance their speed independent of sleep, a capacity that may to be lost in adulthood. Individual differences in the dominant frequency of spindles and slow waves were predictive for performance: children performed better if they had less slow spindles, more fast spindles and faster slow waves. On the other hand, overnight enhancement of accuracy was most pronounced in children with more slow spindles and slower slow waves, i.e., the ones with an initial lower performance. Associations of spindle and slow wave characteristics with initial performance may confound interpretation of their involvement in overnight enhancement. Slower frequencies of characteristic sleep events may mark slower learning and immaturity of networks involved in motor skills. PMID:25426055

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

    Directory of Open Access Journals (Sweden)

    Rebecca G Astill

    2014-11-01

    Full Text Available Background and Aim. The role of sleep in the enhancement of motor skills has been 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 and an association of interindividual differences in skill and sleep characteristics. Methods. 30 children (19 females, 10.7±0.8 years of age; mean±SD performed finger sequence tapping tasks in a repeated-measures design spanning 4 days including 1 polysomnography night. Initial and delayed performance were assessed over 12 hours of wake; 12 hours with sleep; and 24 hours with wake and sleep. For the 12 hours with sleep, children were assigned to one of three conditions: modulation of slow waves and spindles was attempted using acoustic perturbation, and compared to yoked and no-sound control conditions. Analyses. Mixed effect regression models evaluated the association of sleep, its macrostructure and spindles and slow wave parameters with initial and delayed speed and accuracy.Results and Conclusions. Children enhance their accuracy only over an interval with sleep. Unlike previously reported in adults, children enhance their speed independent of sleep, a capacity that may to be lost in adulthood. Individual differences in the dominant frequency of spindles and slow waves were predictive for performance: children performed better if they had less slow spindles, more fast spindles and faster slow waves. On the other hand, overnight enhancement of accuracy was most pronounced in children with more slow spindles and slower slow waves, i.e. the ones with an initial lower performance. Associations of spindle and slow wave characteristics with initial performance may confound interpretation of their involvement in overnight enhancement. Slower frequencies of characteristic sleep events may mark slower learning and immaturity of networks involved in

  3. Different Effects of Sleep Deprivation and Torpor on EEG Slow-Wave Characteristics in Djungarian Hamsters.

    Science.gov (United States)

    Vyazovskiy, V V; Palchykova, S; Achermann, P; Tobler, I; Deboer, T

    2017-02-01

    It has been shown previously in Djungarian hamsters that the initial electroencephalography (EEG) slow-wave activity (power in the 0.5-4.0 Hz band; SWA) in non-rapid eye movement (NREM) sleep following an episode of daily torpor is consistently enhanced, similar to the SWA increase after sleep deprivation (SD). However, it is unknown whether the network mechanisms underlying the SWA increase after torpor and SD are similar. EEG slow waves recorded in the neocortex during sleep reflect synchronized transitions between periods of activity and silence among large neuronal populations. We therefore set out to investigate characteristics of individual cortical EEG slow waves recorded during NREM sleep after 4 h SD and during sleep after emergence from an episode of daily torpor in adult male Djungarian hamsters. We found that during the first hour after both SD and torpor, the SWA increase was associated with an increase in slow-wave incidence and amplitude. However, the slopes of single slow waves during NREM sleep were steeper in the first hour after SD but not after torpor, and, in contrast to sleep after SD, the magnitude of change in slopes after torpor was unrelated to the changes in SWA. Furthermore, slow-wave slopes decreased progressively within the first 2 h after SD, while a progressive increase in slow-wave slopes was apparent during the first 2 h after torpor. The data suggest that prolonged waking and torpor have different effects on cortical network activity underlying slow-wave characteristics, while resulting in a similar homeostatic sleep response of SWA. We suggest that sleep plays an important role in network homeostasis after both waking and torpor, consistent with a recovery function for both states. © The Author 2017. Published by Oxford University Press.

  4. 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.

  5. Standing Slow MHD Waves in Radiatively Cooling Coronal Loops

    Indian Academy of Sciences (India)

    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 ...

  6. Reverse cochlear propagation in the intact cochlea of the gerbil: Evidence for slow traveling waves

    NARCIS (Netherlands)

    S.W.F. Meenderink; M. van der Heijden (Marcel)

    2010-01-01

    textabstractThe inner ear can produce sounds, but how these otoacoustic emissions back-propagate through the cochlea is currently debated. Two opposing views exist: fast pressure waves in the cochlear fluids and slow traveling waves involving the basilar membrane. Resolving this issue requires

  7. Slowing and stopping of wave in dispersive metamaterial loaded helical guide.

    Science.gov (United States)

    Sharma, Dushyant K; Pathak, Surya K

    2016-02-08

    We propose a dispersive metamaterial loaded helical waveguide (DMLHG) structure that supports slowing and stopping of Electromagnetic (EM) wave. Analytical and computational characterizations have been done to visualize various modal characteristics in detail using the Drude model as a dispersive parameter. It is observed that metamaterial insertion enhances helical guide slow wave behaviour and it supports both forward wave (FW) and backward wave (BW) as well as mode degeneracy. Obtained mode degeneracy mechanism leads to trapping of EM wave. The proposed guide structure provides a dynamic control of wave velocity by varying its physical parameters. Two possible structures are designed and simulated using CST Microwave Studio Software. The simulation results verify the presence of similar characteristics as observed in analytical study such as FW, BW, mode-degeneracy, but in slightly shifted frequency spectrum.

  8. 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.

  9. Slow waves moving near the openings in highly stressed conditions

    Science.gov (United States)

    Guzev, Michail; Makarov, Vladimir

    2017-04-01

    In situ experiments have shown the unusual deformation waves near the openings on high depth of the construction. Process of the wave spreading is beginning after the mining and has two stages of the zonal mesocracking structure formation and development [1]. Extending in a radial direction, the wave poorly fades with distance. For phenomenon modelling the theoretical decision for non-Eucledian models about opening of round cross-section in strongly compressed rock massif is used [2]. The decision qualitatively repeats behaviour of a wave in a rock mass, adjustment of phenomenological parametres is executed. References [1] Vladimir V. Makarov, Mikhail A. Guzev, Vladimir N. Odintsev, Lyudmila S. Ksendzenko (2016) Periodical zonal character of damage near the openings in highly-stressed rock mass conditions. Journal of Rock Mechanics and Geotechnical Engineering. Volume 8, Issue 2, pp. 164-169. [2] M.A. Guzev, V.V. Makarov, 2007. Deforming and failure of the high stressed rocks around the openings, RAS Edit., Vladivostok, 2007, P. 232 (in Russian).

  10. Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves

    Science.gov (United States)

    Nakariakov, V. M.; Afanasyev, A. N.; Kumar, S.; Moon, Y.-J.

    2017-11-01

    Evolution of slow magnetoacoustic waves guided by a cylindrical magnetic flux tube that represents a coronal loop or plume, is modeled accounting for the effects of finite gas pressure, weak nonlinearity, dissipation by thermal conduction and viscosity, and the misbalance between the cooling by optically thin radiation and unspecified heating of the plasma. An evolutionary equation of the Burgers–Malthus type is derived. It is shown that the cooling/heating misbalance, determined by the derivatives of the combined radiative cooling and heating function, with respect to the density, temperature, and magnetic field at the thermal equilibrium affect the wave rather strongly. This effect may either cause additional damping, or counteract it, or lead to the gradual amplification of the wave. In the latter case, the coronal plasma acts as an active medium for the slow magnetoacoustic waves. The effect of the cooling/heating misbalance could be important for coronal slow waves, and could be responsible for certain discrepancies between theoretical results and observations, in particular, the increased or decreased damping lengths and times, detection of the waves at certain heights only, and excitation of compressive oscillations. The results obtained open up a possibility for the diagnostics of the coronal heating function by slow magnetoacoustic waves.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    We present a far-field optical technique allowing the measurement of the dispersion relation of electromagnetic fields propagating under the light cone in photonic nanostuctures. It relies on the use of a one-dimensional grating to probe the evanescent tail of the guided field in combination...... 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....

  12. Slow wave sleep induced by GABA agonist tiagabine fails to benefit memory consolidation.

    Science.gov (United States)

    Feld, Gordon B; Wilhelm, Ines; Ma, Ying; Groch, Sabine; Binkofski, Ferdinand; Mölle, Matthias; Born, Jan

    2013-09-01

    Slow wave sleep (SWS) plays a pivotal role in consolidating memories. Tiagabine has been shown to increase SWS in favor of REM sleep without impacting subjective sleep. However, it is unknown whether this effect is paralleled by an improved sleep-dependent consolidation of memory. This double-blind within-subject crossover study tested sensitivity of overnight retention of declarative neutral and emotional materials (word pairs, pictures) as well as a procedural memory task (sequence finger tapping) to oral administration of placebo or 10 mg tiagabine (at 22:30). Fourteen healthy young men aged 21.9 years (range 18-28 years). Tiagabine significantly increased the time spent in SWS and decreased REM sleep compared to placebo. Tiagabine also enhanced slow wave activity (0.5-4.0 Hz) and density of sleep. Fast (12-15 Hz) and slow (9-12 Hz) spindle activity, in particular that occurring phase-locked to the slow oscillation cycle, was decreased following tiagabine. Despite signs of deeper and more SWS, overnight retention of memory tested after sleep the next evening (19:30) was generally not improved after tiagabine, but on average even lower than after placebo, with this impairing effect reaching significance for procedural sequence finger tapping. Our data show that increasing slow wave sleep with tiagabine does not improve memory consolidation. Possibly this is due to functional differences from normal slow wave sleep, i.e., the concurrent suppressive influence of tiagabine on phase-locked spindle activity.

  13. Role of Somatostatin-Positive Cortical Interneurons in the Generation of Sleep Slow Waves.

    Science.gov (United States)

    Funk, Chadd M; Peelman, Kayla; Bellesi, Michele; Marshall, William; Cirelli, Chiara; Tononi, Giulio

    2017-09-20

    During non-rapid eye-movement (NREM) sleep, cortical and thalamic neurons oscillate every second or so between ON periods, characterized by membrane depolarization and wake-like tonic firing, and OFF periods, characterized by membrane hyperpolarization and neuronal silence. Cortical slow waves, the hallmark of NREM sleep, reflect near-synchronous OFF periods in cortical neurons. However, the mechanisms triggering such OFF periods are unclear, as there is little evidence for somatic inhibition. We studied cortical inhibitory interneurons that express somatostatin (SOM), because ∼70% of them are Martinotti cells that target diffusely layer I and can block excitatory transmission presynaptically, at glutamatergic terminals, and postsynaptically, at apical dendrites, without inhibiting the soma. In freely moving male mice, we show that SOM+ cells can fire immediately before slow waves and their optogenetic stimulation during ON periods of NREM sleep triggers long OFF periods. Next, we show that chemogenetic activation of SOM+ cells increases slow-wave activity (SWA), slope of individual slow waves, and NREM sleep duration; whereas their chemogenetic inhibition decreases SWA and slow-wave incidence without changing time spent in NREM sleep. By contrast, activation of parvalbumin+ (PV+) cells, the most numerous population of cortical inhibitory neurons, greatly decreases SWA and cortical firing, triggers short OFF periods in NREM sleep, and increases NREM sleep duration. Thus SOM+ cells, but not PV+ cells, are involved in the generation of sleep slow waves. Whether Martinotti cells are solely responsible for this effect, or are complemented by other classes of inhibitory neurons, remains to be investigated. SIGNIFICANCE STATEMENT Cortical slow waves are a defining feature of non-rapid eye-movement (NREM) sleep and are thought to be important for many of its restorative benefits. Yet, the mechanism by which cortical neurons abruptly and synchronously cease firing, the

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

    DEFF Research Database (Denmark)

    Amini Afshar, Mostafa

    The objective of this project was to develop a calculation tool for the added resistance of ships in ocean waves. To this end a linear potential flow time-domain numerical seakeeping solver has been developed. The solver is based on highorder finite-difference schemes on overlapping grids and has...... 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......-surface boundary conditions. The field continuity equation has been discretised by a centered fourth-order finite difference scheme which also includes ghost layers at the boundaries. For the zero-speed hydrodynamic problem, the same centered scheme can be utilised to calculate the free-surface derivatives...

  15. The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation.

    Science.gov (United States)

    Miyamoto, Daisuke; Hirai, Daichi; Murayama, Masanori

    2017-01-01

    Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5-4 Hz) are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC) have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent) memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation). Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep.

  16. The Roles of Cortical Slow Waves in Synaptic Plasticity and Memory Consolidation

    Directory of Open Access Journals (Sweden)

    Daisuke Miyamoto

    2017-11-01

    Full Text Available Sleep plays important roles in sensory and motor memory consolidation. Sleep oscillations, reflecting neural population activity, involve the reactivation of learning-related neurons and regulate synaptic strength and, thereby affect memory consolidation. Among sleep oscillations, slow waves (0.5–4 Hz are closely associated with memory consolidation. For example, slow-wave power is regulated in an experience-dependent manner and correlates with acquired memory. Furthermore, manipulating slow waves can enhance or impair memory consolidation. During slow wave sleep, inter-areal interactions between the cortex and hippocampus (HC have been proposed to consolidate declarative memory; however, interactions for non-declarative (HC-independent memory remain largely uninvestigated. We recently showed that the directional influence in a slow-wave range through a top-down cortical long-range circuit is involved in the consolidation of non-declarative memory. At the synaptic level, the average cortical synaptic strength is known to be potentiated during wakefulness and depressed during sleep. Moreover, learning causes plasticity in a subset of synapses, allocating memory to them. Sleep may help to differentiate synaptic strength between allocated and non-allocated synapses (i.e., improving the signal-to-noise ratio, which may facilitate memory consolidation. Herein, we offer perspectives on inter-areal interactions and synaptic plasticity for memory consolidation during sleep.

  17. Slow upper mantle beneath Southern Norway from surface waves

    Science.gov (United States)

    Weidle, C.; Maupin, V.

    2009-04-01

    A recent regional surface wave tomography for Northern Europe revealed unprecedented images of the upper mantle beneath the (Tertiary) North Atlantic and the bordering Fennoscandian craton of Archean-Proterozoic age. With respect to the circum-Atlantic regions of uplift, no common mantle pattern supporting the uplift of these regions is observed. The western boundary of the thick cratonic lithosphere follows the trend of the continental margin offshore northern Norway (i.e. the northern Scandes are underlain by thick lithosphere) whereas further south the boundary of the craton is located further east beneath southwestern Sweden. SV shear wave velocities beneath southern Norway are 10% slower than ak135 (at 70-115 km depth) and these low-velocities are clearly connected to the North Atlantic low-velocity regime through a ~ 400 km wide "channel". The low-velocity anomaly beneath Southern Norway coincides in geometry roughly with the dome-like high topography of the southern Scandes and may thus have a non-negligible contribution to the isostatic balance of the region. The amplitude and depth-distribution of this anomaly are due to be further constrained by new data that were acquired during the MAGNUS experiment in 2006-2008. The temporary seismic network, consisting of 40 broadband seismometers covers to a large extent the location of the anomaly as imaged by the regional tomography. This enables us to get unique control on the tomographic model at improved lateral and vertical resolution. Preliminary analysis of surface wave phase velocities yields an average 1-D shear wave velocity profile for southern Norway as a first step to constrain the presence and depth extent of this low-velocity anomaly.

  18. U-shaped meander-line slow-wave structure with stub-loading

    Science.gov (United States)

    Bian, Xingwang; Miao, Min; Li, Zhensong; Cui, Xiaole

    2017-06-01

    In this paper, a U-shaped meander-line slow-wave structure (SWS) with stub-loading is proposed for applications in Ka-band traveling-wave tube (TWT). This new slow-wave structure, loaded with a stub at the center of the U-turn section, has higher interaction impedance and lower phase velocity compared with conventional U-shaped meander-line SWSs, indicating that the devices based on this structure may have a lower operating voltage and higher output power. The dispersion characteristic, interaction impedance, transmission characteristics, and beam-wave interaction are simulated by utilizing simulation tool. The simulation result predicts that the millimeter-wave traveling-wave tube design based on this slow-wave structure is capable of delivering over 200 W with a gain of 33 dB and interaction efficiency 14.5% at the center frequency 34 GHz. This design, more compact and powerful in comparison with those based on more conventional vacuum electronic mechanisms, is demonstrated as a prospective option for integrated millimeter-wave power modules (MMPMs) empowering a broad spectrum of fields, from target detection, to imaging and telecommunications, among others.

  19. Medical management with diazepam for electrical status epilepticus during slow wave sleep in children.

    Science.gov (United States)

    Francois, Densley; Roberts, Jessica; Hess, Stephany; Probst, Luke; Eksioglu, Yaman

    2014-03-01

    Oral diazepam, administered in varying doses, is among the few proposed treatment options for electrical status epilepticus during slow wave sleep in children. We sought to retrospectively evaluate the long-term efficacy of high-dose oral diazepam in reducing electrographic and clinical evidence of electrical status epilepticus during slow wave sleep in children. Additionally, we surveyed caregivers to assess safety and behavioral outcomes related to ongoing therapy. We collected demographic and clinical data on children treated for electrical status epilepticus during slow wave sleep between October 2010 and March 2013. We sought to identify the number of patients who achieved at least a 50% reduction in spike wave index on electroencephalograph after receiving high-dose oral diazepam. We also administered a questionnaire to caregivers to assess for behavioral problems and side effects. We identified 42 evaluable patients who received high-dose diazepam (range 0.23-2.02 mg/kg per day) to treat electrical status epilepticus during slow wave sleep. Twenty-six patients had spike reduction data and 18/26 (69.2%) children achieved a greater than 50% reduction in spike wave count from an average of 15.54 to 5.05 (P = 0.001). We received 28 responses to the questionnaire. Some patients experienced new onset of difficulties with problem-solving and speech and writing development. Sleep disturbances (50%) and irritability (57.1%) were the most frequent side effects reported. There did not appear to be a dose-related effect with electroencephalograph changes, behavioral effects, or side effects. High-dose oral diazepam significantly reduces the spike wave count on electroencephalograph in children with electrical status epilepticus during slow wave sleep. Although this therapy improves electroencephalograph-related findings, it can be associated with concerning neurological and behavioral side effects in some individuals, so further study is warranted. Copyright © 2014

  20. Multi-channel wireless mapping of gastrointestinal serosal slow wave propagation.

    Science.gov (United States)

    Paskaranandavadivel, N; Wang, R; Sathar, S; O'Grady, G; Cheng, L K; Farajidavar, A

    2015-04-01

    High-resolution (HR) extracellular mapping allows accurate profiling of normal and dysrhythmic slow wave patterns. A current limitation is that cables traverse the abdominal wall or a natural orifice, risking discomfort, dislodgement or infection. Wireless approaches offer advantages, but a multi-channel system is required, capable of recording slow waves and mapping propagation with high fidelity. A novel multi-channel (n = 7) wireless mapping system was developed and compared to a wired commercial system. Slow wave signals were recorded from the porcine gastric and intestinal serosa in vivo. Signals were simultaneously acquired using both systems, and were filtered and processed to map activation wavefronts. For validation, the frequency and amplitude of detected events were compared, together with the speed and direction of mapped wavefronts. The wireless device achieved comparable signal quality to the reference device, and slow wave frequencies were identical. Amplitudes of the acquired gastric and intestinal slow wave signals were consistent between the devices. During normal propagation, spatiotemporal mapping remained accurate in the wireless system, however, during ectopic dysrhythmic pacemaking, the lower sampling resolution of the wireless device led to reduced accuracy in spatiotemporal mapping. A novel multichannel wireless device is presented for mapping slow wave activity. The device achieved high quality signals, and has the potential to facilitate chronic monitoring studies and clinical translation of spatiotemporal mapping. The current implementation may be applied to detect normal patterns and dysrhythmia onset, but HR mapping with finely spaced arrays currently remains necessary to accurately define dysrhythmic patterns. © 2015 John Wiley & Sons Ltd.

  1. Sleep-dependent improvement in visuomotor learning: a causal role for slow waves.

    Science.gov (United States)

    Landsness, Eric C; Crupi, Domenica; Hulse, Brad K; Peterson, Michael J; Huber, Reto; Ansari, Hidayath; Coen, Michael; Cirelli, Chiara; Benca, Ruth M; Ghilardi, M Felice; Tononi, Giulio

    2009-10-01

    Sleep after learning often benefits memory consolidation, but the underlying mechanisms remain unclear. In previous studies, we found that learning a visuomotor task is followed by an increase in sleep slow wave activity (SWA, the electroencephalographic [EEG] power density between 0.5 and 4.5 Hz during non-rapid eye movement sleep) over the right parietal cortex. The SWA increase correlates with the postsleep improvement in visuomotor performance, suggesting that SWA may be causally responsible for the consolidation of visuomotor learning. Here, we tested this hypothesis by studying the effects of slow wave deprivation (SWD). After learning the task, subjects went to sleep, and acoustic stimuli were timed either to suppress slow waves (SWD) or to interfere as little as possible with spontaneous slow waves (control acoustic stimulation, CAS). Sound-attenuated research room. Healthy subjects (mean age 24.6 +/- 1.0 years; n = 9 for EEG analysis, n = 12 for behavior analysis; 3 women). Sleep time and efficiency were not affected, whereas SWA and the number of slow waves decreased in SWD relative to CAS. Relative to the night before, visuomotor performance significantly improved in the CAS condition (+5.93% +/- 0.88%) but not in the SWD condition (-0.77% +/- 1.16%), and the direct CAS vs SWD comparison showed a significant difference (P = 0.0007, n = 12, paired t test). Changes in visuomotor performance after SWD were correlated with SWA changes over right parietal cortex but not with the number of arousals identified using clinically established criteria, nor with any sign of "EEG lightening" identified using a novel automatic method based on event-related spectral perturbation analysis. These results support a causal role for sleep slow waves in sleep-dependent improvement of visuomotor performance.

  2. Role of slow oscillatory activity and slow wave sleep in consolidation of episodic-like memory in rats.

    Science.gov (United States)

    Oyanedel, Carlos N; Binder, Sonja; Kelemen, Eduard; Petersen, Kimberley; Born, Jan; Inostroza, Marion

    2014-12-15

    Our previous experiments showed that sleep in rats enhances consolidation of hippocampus dependent episodic-like memory, i.e. the ability to remember an event bound into specific spatio-temporal context. Here we tested the hypothesis that this enhancing effect of sleep is linked to the occurrence of slow oscillatory and spindle activity during slow wave sleep (SWS). Rats were tested on an episodic-like memory task and on three additional tasks covering separately the where (object place recognition), when (temporal memory), and what (novel object recognition) components of episodic memory. In each task, the sample phase (encoding) was followed by an 80-min retention interval that covered either a period of regular morning sleep or sleep deprivation. Memory during retrieval was tested using preferential exploration of novelty vs. familiarity. Consistent with previous findings, the rats which had slept during the retention interval showed significantly stronger episodic-like memory and spatial memory, and a trend of improved temporal memory (although not significant). Object recognition memory was similarly retained across sleep and sleep deprivation retention intervals. Recall of episodic-like memory was associated with increased slow oscillatory activity (0.85-2.0Hz) during SWS in the retention interval. Spatial memory was associated with increased proportions of SWS. Against our hypothesis, a relationship between spindle activity and episodic-like memory performance was not detected, but spindle activity was associated with object recognition memory. The results provide support for the role of SWS and slow oscillatory activity in consolidating hippocampus-dependent memory, the role of spindles in this process needs to be further examined. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  3. A role for cortical nNOS/NK1 neurons in coupling homeostatic sleep drive to EEG slow wave activity

    OpenAIRE

    Morairty, Stephen R.; Dittrich, Lars; Pasumarthi, Ravi K.; Valladao, Daniel; Heiss, Jaime E.; Gerashchenko, Dmitry; Kilduff, Thomas S.

    2013-01-01

    Sleep is a homeostatically regulated process. Slow wave sleep is characterized by slow waves detectable from the cerebral cortex by EEG. When homeostatic sleep “drive” is manipulated by varying durations of sleep deprivation, the intensity of EEG slow waves proportionally increases. The neural circuitry underlying this homeostatic response is little understood. In this study we describe a systematic relationship between homeostatic sleep drive and activation of cortical neurons that express n...

  4. Overnight Changes in the Slope of Sleep Slow Waves during Infancy

    Science.gov (United States)

    Fattinger, Sara; Jenni, Oskar G.; Schmitt, Bernhard; Achermann, Peter; Huber, Reto

    2014-01-01

    Study Objectives: Slow wave activity (SWA, 0.5-4.5 Hz) is a well-established marker for sleep pressure in adults. Recent studies have shown that increasing sleep pressure is reflected by an increased synchronized firing pattern of cortical neurons, which can be measured by the slope of sleep slow waves. Thus we aimed at investigating whether the slope of sleep slow waves might provide an alternative marker to study the homeostatic regulation of sleep during early human development. Design: All-night sleep electroencephalography (EEG) was recorded longitudinally at 2, 4, 6, and 9 months after birth. Setting: Home recording. Patients or Participants: 11 healthy full-term infants (5 male, 6 female). Interventions: None Measurements and Results: The slope of sleep slow waves increased with age. At all ages the slope decreased from the first to the last hour of non rapid-eye-movement (NREM) sleep, even when controlling for amplitude differences (P waves during infancy. SLEEP 2014;37(2):245-253. PMID:24497653

  5. Shorter duration of non-rapid eye movement sleep slow waves in EphA4 knockout mice.

    Science.gov (United States)

    Freyburger, Marlène; Poirier, Gaétan; Carrier, Julie; Mongrain, Valérie

    2017-10-01

    Slow waves occurring during non-rapid eye movement sleep have been associated with neurobehavioural performance and memory. In addition, the duration of previous wakefulness and sleep impacts characteristics of these slow waves. However, molecular mechanisms regulating the dynamics of slow-wave characteristics remain poorly understood. The EphA4 receptor regulates glutamatergic transmission and synaptic plasticity, which have both been linked to sleep slow waves. To investigate if EphA4 regulates slow-wave characteristics during non-rapid eye movement sleep, we compared individual parameters of slow waves between EphA4 knockout mice and wild-type littermates under baseline conditions and after a 6-h sleep deprivation. We observed that, compared with wild-type mice, knockout mice display a shorter duration of positive and negative phases of slow waves under baseline conditions and after sleep deprivation. However, the mutation did not change slow-wave density, amplitude and slope, and did not affect the sleep deprivation-dependent changes in slow-wave characteristics, suggesting that EphA4 is not involved in the response to elevated sleep pressure. Our present findings suggest a role for EphA4 in shaping cortical oscillations during sleep that is independent from sleep need. © 2017 European Sleep Research Society.

  6. Effect of Particular Nonlinear Dispersion in Photorefractive Four wave Mixing on Slow and Fast Light (Preprint)

    Science.gov (United States)

    2018-01-31

    coupling strength increases. The conclusions of the theoretical analysis are confirmed experimentally for photorefractive four-wave mixing in...fast light Konstantin Shcherbin*a, Pierre Matheyb, and Dean R. Evansc aInstitute of Physics , National Academy of Sciences, Prospekt Nauki 46, 03680...conclusions of the theoretical analysis are confirmed experimentally for photorefractive four-wave mixing in barium titanate. Keywords: slow light

  7. 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.

  8. 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 ...

  9. 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

  10. 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...

  11. A social conflict increases EEG slow-wave activity during subsequent sleep

    NARCIS (Netherlands)

    Meerlo, P; de Bruin, EA; Strijkstra, AM; Daan, S

    2001-01-01

    Electroencephalogram (EEG) slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep is widely viewed as an indicator of sleep debt and sleep intensity. In a previous study, we reported a strong increase in SWA during NREM sleep after a social conflict in rats. To test whether this

  12. Midlife Decline in Declarative Memory Consolidation Is Correlated with a Decline in Slow Wave Sleep

    Science.gov (United States)

    Backhaus, Jutta; Born, Jan; Hoeckesfeld, Ralf; Fokuhl, Sylvia; Hohagen, Fritz; Junghanns, Klaus

    2007-01-01

    Sleep architecture as well as memory function are strongly age dependent. Slow wave sleep (SWS), in particular, decreases dramatically with increasing age, starting already beyond the age of 30. SWS normally predominates during early nocturnal sleep and is implicated in declarative memory consolidation. However, the consequences of changes in…

  13. 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...

  14. 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

  15. 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…

  16. Overnight changes in the slope of sleep slow waves during infancy.

    Science.gov (United States)

    Fattinger, Sara; Jenni, Oskar G; Schmitt, Bernhard; Achermann, Peter; Huber, Reto

    2014-02-01

    Slow wave activity (SWA, 0.5-4.5 Hz) is a well-established marker for sleep pressure in adults. Recent studies have shown that increasing sleep pressure is reflected by an increased synchronized firing pattern of cortical neurons, which can be measured by the slope of sleep slow waves. Thus we aimed at investigating whether the slope of sleep slow waves might provide an alternative marker to study the homeostatic regulation of sleep during early human development. All-night sleep electroencephalography (EEG) was recorded longitudinally at 2, 4, 6, and 9 months after birth. Home recording. 11 healthy full-term infants (5 male, 6 female). None. The slope of sleep slow waves increased with age. At all ages the slope decreased from the first to the last hour of non rapid-eye-movement (NREM) sleep, even when controlling for amplitude differences (P cycle-by-cycle time course across the night (P alternating pattern of low-delta activity (0.75-1.75 Hz) is most prominent. Moreover, we found distinct topographical differences exhibiting the steepest slope over the occipital cortex. The results suggest an age-dependent increase in synchronization of cortical activity during infancy, which might be due to increasing synaptogenesis. Previous studies have shown that during early postnatal development synaptogenesis is most pronounced over the occipital cortex, which could explain why the steepest slope was found in the occipital derivation. Our results provide evidence that the homeostatic regulation of sleep develops early in human infants.

  17. Cortex-wide BOLD fMRI activity reflects locally-recorded slow oscillation-associated calcium waves

    Science.gov (United States)

    Backhaus, Hendrik; Kronfeld, Andrea; Aedo Jury, Felipe; Prouvot, Pierre-Hugues; Fois, Consuelo; Albers, Franziska; van Alst, Timo

    2017-01-01

    Spontaneous slow oscillation-associated slow wave activity represents an internally generated state which is characterized by alternations of network quiescence and stereotypical episodes of neuronal activity - slow wave events. However, it remains unclear which macroscopic signal is related to these active periods of the slow wave rhythm. We used optic fiber-based calcium recordings of local neural populations in cortex and thalamus to detect neurophysiologically defined slow calcium waves in isoflurane anesthetized rats. The individual slow wave events were used for an event-related analysis of simultaneously acquired whole-brain BOLD fMRI. We identified BOLD responses directly related to onsets of slow calcium waves, revealing a cortex-wide BOLD correlate: the entire cortex was engaged in this specific type of slow wave activity. These findings demonstrate a direct relation of defined neurophysiological events to a specific BOLD activity pattern and were confirmed for ongoing slow wave activity by independent component and seed-based analyses. PMID:28914607

  18. Treatment of electrical status epilepticus during slow-wave sleep with high-dose corticosteroid.

    Science.gov (United States)

    Okuyaz, Cetin; Aydin, Kürşad; Gücüyener, Kivilcim; Serdaroğlu, Ayşe

    2005-01-01

    A 4-year-old female patient with epilepsy with continuous spike-and-waves during slow-wave sleep not classified as Landau-Klefner syndrome, refractory to antiepileptic drugs including valproate, benzodiazepines, and lamotrigine, was treated successfully with high-dose intravenous methylprednisolone therapy. Valproate, clobazam, and lamotrigine were continued at the same dose during and after high-dose intravenous corticosteroid therapy. During corticosteroid therapy, awake and sleep electroencephalogram was recorded every day. On day 7, a dramatic clinical and electroencephalographic response was observed. After high-dose intravenous methylprednisolone, prednisolone was administered orally (2 mg/kg daily) for 2 months, then gradually withdrawn. After the withdrawal of corticosteroid therapy, the patient maintained the clinical improvement in behavior, and no continuous spike-and-wave electrical status epilepticus during slow-wave sleep occurred on routine monthly sleep electroencephalogram performed for the last 6 months. In the present case, an add-on high-dose intravenous corticosteroid seems to be effective in the treatment of patients with electrical status epilepticus during slow-wave sleep syndrome, especially when antiepileptic drugs fail.

  19. Excitation of slow waves in front of an ICRF antenna in a basic plasma experiment

    Science.gov (United States)

    Soni, Kunal; van Compernolle, Bart; Crombe, Kristel; van Eester, Dirk

    2017-10-01

    Recent results of ICRF experiments at the Large Plasma Device (LAPD) indicate parasitic coupling to the slow wave by the fast wave antenna. Plasma parameters in LAPD are similar to the scrape-off layer of current fusion devices. The machine has a 17 m long, 60 cm diameter magnetized plasma column with typical plasma parameters ne 1012 -1013 cm-3, Te 1 - 10 eV and B0 1000 G. It was found that coupling to the slow mode occurs when the plasma density in front of the antenna is low enough such that the lower hybrid resonance is present in the plasma. The radial density profile is tailored to allow for fast mode propagation in the high density core and slow mode propagation in the low density edge region. Measurements of the wave fields clearly show two distinct modes, one long wavelength m=1 fast wave mode in the core and a short wavelength backward propagating mode in the edge. Perpendicular wave numbers compare favorably to the predicted values. The experiment was done for varying frequencies, ω /Ωi = 25 , 6 and 1.5. Future experiments will investigate the dependence on antenna tilt angle with respect to the magnetic field, with and without Faraday screen. This work is performed at the Basic Plasma Science Facility, sponsored jointly by DOE and NSF.

  20. Temporal imaging based on four-wave mixing in slow-light photonic crystal waveguide

    Science.gov (United States)

    Zhou, Mingyang; Liu, Hongjun; Wang, Zhaolu; Huang, Nan; Han, Jing

    2017-12-01

    We have proposed a temporal imaging system based on four-wave mixing (FWM) in the dispersion engineered slow-light photonic crystal waveguide (PCW). Dispersion relations of the modified PCW are calculated through the 3D plane wave expansion method. Time lens is demonstrated by solving the couple-mode equations describing the FWM process inside the PCW directly. Intensity and phase evolutions of the signal, pump and idler waves during the FWM process are calculated to investigate temporal imaging. Meanwhile, temporal magnifications with different magnification factors are realized by tuning the total dispersion of the input signals. Furthermore, influences of dispersion and free-carrier effects inside PCW on the temporal imaging performance are analyzed. The simulation results show the capability to realize temporal imaging system based on the FWM process in slow-light engineered PCW.

  1. Slow-wave sleep and the consolidation of long-term memory.

    Science.gov (United States)

    Born, Jan

    2010-06-01

    Slow-wave sleep (SWS) has been shown to play an important role in the reinforcement of declarative memory. A dialogue between the neocortex and hippocampus is important during this consolidation and appears to be largely regulated by silence. Grouping is not only induced in the neocortex but also in other relevant structures, such as the thalamus and the hippocampus, generating spindle activity and sharp-wave ripples, respectively. Sharp-wave ripples are known to accompany a memory replay of encoded information in the hippocampus during SWS which stimulates the transfer of this memory-related information to the neocortex. The slow oscillations synchronize this transfer with the thalamocortical spindles arriving at the neocortex at the same time as the hippocampal memory information. This synchronization is thought to be critical to the long-term storage of respective memories within neocortical networks.

  2. 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)....

  3. Effects of partial sleep deprivation on slow waves during non-rapid eye movement sleep: A high density EEG investigation.

    Science.gov (United States)

    Plante, David T; Goldstein, Michael R; Cook, Jesse D; Smith, Richard; Riedner, Brady A; Rumble, Meredith E; Jelenchick, Lauren; Roth, Andrea; Tononi, Giulio; Benca, Ruth M; Peterson, Michael J

    2016-02-01

    Changes in slow waves during non-rapid eye movement (NREM) sleep in response to acute total sleep deprivation are well-established measures of sleep homeostasis. This investigation utilized high-density electroencephalography (hdEEG) to examine topographic changes in slow waves during repeated partial sleep deprivation. Twenty-four participants underwent a 6-day sleep restriction protocol. Spectral and period-amplitude analyses of sleep hdEEG data were used to examine changes in slow wave energy, count, amplitude, and slope relative to baseline. Changes in slow wave energy were dependent on the quantity of NREM sleep utilized for analysis, with widespread increases during sleep restriction and recovery when comparing data from the first portion of the sleep period, but restricted to recovery sleep if the entire sleep episode was considered. Period-amplitude analysis was less dependent on the quantity of NREM sleep utilized, and demonstrated topographic changes in the count, amplitude, and distribution of slow waves, with frontal increases in slow wave amplitude, numbers of high-amplitude waves, and amplitude/slopes of low amplitude waves resulting from partial sleep deprivation. Topographic changes in slow waves occur across the course of partial sleep restriction and recovery. These results demonstrate a homeostatic response to partial sleep loss in humans. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Effects of partial sleep deprivation on slow waves during non-rapid eye movement sleep: a high density EEG investigation

    Science.gov (United States)

    Plante, David T.; Goldstein, Michael R.; Cook, Jesse D.; Smith, Richard; Riedner, Brady A.; Rumble, Meredith E.; Jelenchick, Lauren; Roth, Andrea; Tononi, Giulio; Benca, Ruth M.; Peterson, Michael J.

    2015-01-01

    Objective Changes in slow waves during non-rapid eye movement (NREM) sleep in response to acute total sleep deprivation are well-established measures of sleep homeostasis. This investigation utilized high-density electroencephalography (hdEEG) to examine topographic changes in slow waves during repeated partial sleep deprivation. Methods Twenty-four participants underwent a 6-day sleep restriction protocol. Spectral and period-amplitude analyses of sleep hdEEG data were used to examine changes in slow wave energy, count, amplitude, and slope relative to baseline. Results Changes in slow wave energy were dependent on the quantity of NREM sleep utilized for analysis, with widespread increases during sleep restriction and recovery when comparing data from the first portion of the sleep period, but restricted to recovery sleep if the entire sleep episode was considered. Period-amplitude analysis was less dependent on the quantity of NREM sleep utilized, and demonstrated topographic changes in the count, amplitude, and distribution of slow waves, with frontal increases in slow wave amplitude, numbers of high-amplitude waves, and amplitude/slopes of low amplitude waves resulting from partial sleep deprivation. Conclusions Topographic changes in slow waves occur across the course of partial sleep restriction and recovery. Significance These results demonstrate a homeostatic response to partial sleep loss in humans. PMID:26596212

  5. Slow waves in microchannel metal waveguides and application to particle acceleration

    Directory of Open Access Journals (Sweden)

    L. C. Steinhauer

    2003-06-01

    Full Text Available Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong exchange of energy can occur between a beam of charged particles and this slow-waveguide mode. Moreover, the energy exchange can be sustained over a distance limited only by the natural damping of the wave. This makes the microchannel metal waveguide an attractive possibility for high-gradient electron laser acceleration because the wave can be directly energized by a long-wavelength laser. Indeed the frequency of CO_{2} lasers lies at a fortuitous wavelength that produces a strong laser-particle interaction in a channel of reasonable macroscopic size (e.g., ∼0.6  mm. The dispersion properties including phase velocity and damping for the slow wave are developed. The performance and other issues related to laser accelerator applications are discussed.

  6. Slow waves in microchannel metal waveguides and application to particle acceleration

    Science.gov (United States)

    Steinhauer, L. C.; Kimura, W. D.

    2003-06-01

    Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong exchange of energy can occur between a beam of charged particles and this slow-waveguide mode. Moreover, the energy exchange can be sustained over a distance limited only by the natural damping of the wave. This makes the microchannel metal waveguide an attractive possibility for high-gradient electron laser acceleration because the wave can be directly energized by a long-wavelength laser. Indeed the frequency of CO2 lasers lies at a fortuitous wavelength that produces a strong laser-particle interaction in a channel of reasonable macroscopic size (e.g., ˜0.6 mm). The dispersion properties including phase velocity and damping for the slow wave are developed. The performance and other issues related to laser accelerator applications are discussed.

  7. Concomitant BDNF and sleep slow wave changes indicate ketamine-induced plasticity in major depressive disorder.

    Science.gov (United States)

    Duncan, Wallace C; Sarasso, Simone; Ferrarelli, Fabio; Selter, Jessica; Riedner, Brady A; Hejazi, Nadia S; Yuan, Peixiong; Brutsche, Nancy; Manji, Husseini K; Tononi, Giulio; Zarate, Carlos A

    2013-03-01

    The N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has rapid antidepressant effects in treatment-resistant major depressive disorder (MDD). In rats, ketamine selectively increased electroencephalogram (EEG) slow wave activity (SWA) during non-rapid eye movement (REM) sleep and altered central brain-derived neurotrophic factor (BDNF) expression. Taken together, these findings suggest that higher SWA and BDNF levels may respectively represent electrophysiological and molecular correlates of mood improvement following ketamine treatment. This study investigated the acute effects of a single ketamine infusion on depressive symptoms, EEG SWA, individual slow wave parameters (surrogate markers of central synaptic plasticity) and plasma BDNF (a peripheral marker of plasticity) in 30 patients with treatment-resistant MDD. Montgomery-Åsberg Depression Rating Scale scores rapidly decreased following ketamine. Compared to baseline, BDNF levels and early sleep SWA (during the first non-REM episode) increased after ketamine. The occurrence of high amplitude waves increased during early sleep, accompanied by an increase in slow wave slope, consistent with increased synaptic strength. Changes in BDNF levels were proportional to changes in EEG parameters. Intriguingly, this link was present only in patients who responded to ketamine treatment, suggesting that enhanced synaptic plasticity - as reflected by increased SWA, individual slow wave parameters and plasma BDNF - is part of the physiological mechanism underlying the rapid antidepressant effects of NMDA antagonists. Further studies are required to confirm the link found here between behavioural and synaptic changes, as well as to test the reliability of these central and peripheral biomarkers of rapid antidepressant response.

  8. Slow feature analysis on retinal waves leads to V1 complex cells.

    Directory of Open Access Journals (Sweden)

    Sven Dähne

    2014-05-01

    Full Text Available The developing visual system of many mammalian species is partially structured and organized even before the onset of vision. Spontaneous neural activity, which spreads in waves across the retina, has been suggested to play a major role in these prenatal structuring processes. Recently, it has been shown that when employing an efficient coding strategy, such as sparse coding, these retinal activity patterns lead to basis functions that resemble optimal stimuli of simple cells in primary visual cortex (V1. Here we present the results of applying a coding strategy that optimizes for temporal slowness, namely Slow Feature Analysis (SFA, to a biologically plausible model of retinal waves. Previously, SFA has been successfully applied to model parts of the visual system, most notably in reproducing a rich set of complex-cell features by training SFA with quasi-natural image sequences. In the present work, we obtain SFA units that share a number of properties with cortical complex-cells by training on simulated retinal waves. The emergence of two distinct properties of the SFA units (phase invariance and orientation tuning is thoroughly investigated via control experiments and mathematical analysis of the input-output functions found by SFA. The results support the idea that retinal waves share relevant temporal and spatial properties with natural visual input. Hence, retinal waves seem suitable training stimuli to learn invariances and thereby shape the developing early visual system such that it is best prepared for coding input from the natural world.

  9. Are spatial memories strengthened in the human hippocampus during slow wave sleep?

    Science.gov (United States)

    Peigneux, Philippe; Laureys, Steven; Fuchs, Sonia; Collette, Fabienne; Perrin, Fabien; Reggers, Jean; Phillips, Christophe; Degueldre, Christian; Del Fiore, Guy; Aerts, Joël; Luxen, André; Maquet, Pierre

    2004-10-28

    In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of spatial memories. Here, using regional cerebral blood flow measurements, we show that, in humans, hippocampal areas that are activated during route learning in a virtual town are likewise activated during subsequent slow wave sleep. Most importantly, we found that the amount of hippocampal activity expressed during slow wave sleep positively correlates with the improvement of performance in route retrieval on the next day. These findings suggest that learning-dependent modulation in hippocampal activity during human sleep reflects the offline processing of recent episodic and spatial memory traces, which eventually leads to the plastic changes underlying the subsequent improvement in performance.

  10. Probing slow dynamics of consolidated granular multicomposite materials by diffuse acoustic wave spectroscopy.

    Science.gov (United States)

    Tremblay, Nicolas; Larose, Eric; Rossetto, Vincent

    2010-03-01

    The stiffness of a consolidated granular medium experiences a drop immediately after a moderate mechanical solicitation. Then the stiffness rises back toward its initial value, following a logarithmic time evolution called slow dynamics. In the literature, slow dynamics has been probed by macroscopic quantities averaged over the sample volume, for instance, by the resonant frequency of vibrational eigenmodes. This article presents a different approach based on diffuse acoustic wave spectroscopy, a technique that is directly sensitive to the details of the sample structure. The parameters of the dynamics are found to depend on the damage of the medium. Results confirm that slow dynamics is, at least in part, due to tiny structural rearrangements at the microscopic scale, such as inter-grain contacts.

  11. Slow waves in microchannel metal waveguides and application to particle acceleration

    OpenAIRE

    L. C. Steinhauer; W. D. Kimura

    2003-01-01

    Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong ex...

  12. Slow wave and rapid eye movement sleep deprivation: differing impacts on memory consolidation?

    OpenAIRE

    Solomons, Luke

    2016-01-01

    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. 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. Participants had one control night of undisturbed sl...

  13. 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, M D

    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...

  14. Are Spatial Memories Strengthened in the Human Hippocampus during Slow Wave Sleep?

    OpenAIRE

    Peigneux, Philippe; Laureys, Steven; Fuchs, Sonia; Collette, Fabienne; Perrin, Fabien; Reggers, Jean; Phillips, Christophe; Degueldre, Christian; Del Fiore, Guy; Aerts, Joël; Luxen, André; Maquet, Pierre

    2004-01-01

    In rats, the firing sequences observed in hippocampal ensembles during spatial learning are replayed during subsequent sleep, suggesting a role for posttraining sleep periods in the offline processing of spatial memories. Here, using regional cerebral blood flow measurements, we show that, in humans, hippocampal areas that are activated during route learning in a virtual town are likewise activated during subsequent slow wave sleep. Most importantly, we found that the amount of hippocampal ac...

  15. 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

  16. 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.

  17. Slow-wave sleep deficiency and enhancement: implications for insomnia and its management.

    Science.gov (United States)

    Dijk, Derk-Jan

    2010-06-01

    In humans, slow-wave sleep (SWS) consists of stages 3 and 4 of non rapid eye movement (nonREM) sleep. The low-frequency, high-amplitude slow waves that dominate the electroencephalogram (EEG) during SWS can be quantified as slow-wave activity (SWA). SWS and SWA are regulated very accurately in response to variations in the duration and intensity of wakefulness and sleep. SWA declines more or less independently of circadian phase during the course of a sleep episode, indicating that it is primarily under homeostatic rather than circadian control. An age-related decline in SWS and SWA is well established. In some studies, apprehension, depression and insomnia have been associated with reductions in SWS and SWA. Experimental reductions of SWS through SWS deprivation (without altering total sleep time or REM duration) have been reported to lead to an increase in daytime sleep propensity and reductions in performance. SWS and SWA are therefore thought to contribute to the recovery processes that occur during sleep. Most currently prescribed hypnotics, such as the benzodiazepines and Z-drugs, suppress SWA. Some compounds have been shown to enhance SWS and SWA in healthy volunteers through GAT-1 inhibition, GABA-A modulation, GABA-B modulation, and 5HT2(A) antagonism. Pharmacological enhancement of SWS has also been observed in insomnia. The effects of SWS enhancement on other sleep parameters will be discussed.

  18. High Amplitude Background Slow Waves in Normal Children Aged 3 to 18 Months-Implications for the Consideration of Hypsarhythmia.

    Science.gov (United States)

    Mytinger, John R; Weber, Amanda; Vidaurre, Jorge

    2018-01-08

    To assess for the presence of high amplitude EEG background slow waves in normal young children. One hundred children with normal development ages 3 to 18 months had normal EEGs for spells and did not have seizures or epilepsy. Three electroencephalographers retrospectively reviewed 5 minutes of stable stage II sleep to measure background slow waves for peak-to-peak amplitudes. A standard 10-20 longitudinal bipolar montage was used. Interrater agreement was assessed by intraclass correlation coefficient. Interrater agreement between reviewers in the assessment of recurrent slow wave amplitudes was excellent (intraclass correlation coefficient = 0.97). Slow wave amplitudes were the highest in the posterior head regions for all patients. We found recurring slow waves of 500 µV in 17%, 49%, 30%, 3% and 1%, respectively. Although hypsarhythmia typically includes high amplitude background slow waves of >200 or >300 µV, we found that 83% and 34% of normal children had recurring posterior background slow waves of >200 or >300 µV, respectively. These data may be useful in the EEG background assessment of young children, for determining the presence or absence of hypsarhythmia, and determining treatment response in children with epileptic spasms.

  19. Slow vs rapid delivery rate shock wave lithotripsy for pediatric renal urolithiasis: a prospective randomized study.

    Science.gov (United States)

    Salem, Hosni Khairy; Fathy, Hesham; Elfayoumy, Hanny; Aly, Hussein; Ghonium, Ahmed; Mohsen, Mostafa A; Hegazy, Abd El Rahim

    2014-05-01

    We compared slow vs fast shock wave frequency rates in disintegration of pediatric renal stones less than 20 mm. Our study included 60 children with solitary 10 to 20 mm radiopaque renal stones treated with shock wave lithotripsy. Patients were prospectively randomized into 2 groups, ie those undergoing lithotripsy at a rate of 80 shock waves per minute (group 1, 30 patients) and those undergoing lithotripsy at a rate of 120 shock waves per minute (group 2, 30 patients). The 2 groups were compared in terms of treatment success, anesthesia time, secondary procedures and efficiency quotient. Stone clearance rate was significantly higher in group 1 (90%) than in group 2 (73.3%, p = 0.025). A total of 18 patients in group 1 (60%) were rendered stone-free after 1 session, 8 required 2 sessions and 1 needed 3 sessions, while shock wave lithotripsy failed in 3 patients. By comparison, 8 patients (26.6%) in group 2 were rendered stone-free after 1 session, 10 (33.3%) required 2 sessions and 4 (13.3%) needed 3 sessions to become stone-free. Mean general anesthesia time was significantly longer in group 1 (p = 0.041). Postoperatively 2 patients in group 1 and 4 in group 2 suffered low grade fever (Clavien grade II). Significantly more secondary procedures (percutaneous nephrolithotomy, repeat shock wave lithotripsy) were required in group 2 (p = 0.005). The predominant stone analysis was calcium oxalate dihydrate in both groups. Efficiency quotient was 0.5869 and 0.3437 for group 1 and group 2, respectively (p = 0.0247). In children with renal stones slow delivery rates of shock wave lithotripsy have better results regarding stone clearance than fast delivery rates. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  20. One dimensional full wave analysis of slow-to-fast mode conversion in lower hybrid frequencies

    Science.gov (United States)

    Jia, Guo-Zhang; Gao, Zhe

    2014-12-01

    The linear conversion from the slow wave to the fast wave in the lower hybrid range of frequencies is analyzed numerically by using the set of field equations describing waves in a cold plane-stratified plasma. The equations are solved as a two-point boundary value problem, where the polarizations of each mode are set consistently in the boundary conditions. The scattering coefficients and the field patterns are obtained for various density profiles. It is shown that, for large density scale length, the results agree well with the traditional cognitions. In contrast, the reflected component and the probable transmitted-converted component from the conversion region, which are neglected in the usual calculations, become significant when the scale length is smaller than the wavelength of the mode. The inclusion of these new components will improve the accuracy of the simulated propagation and deposition for the injected rf power when the conversion process is involved within a sharp-varying density profile. Meanwhile, the accessibility of the incident slow wave for the low frequency case is also affected by the scale length of the density profile.

  1. First Imaging Observation of Standing Slow Wave in Coronal Fan Loops

    Energy Technology Data Exchange (ETDEWEB)

    Pant, V.; Tiwari, A.; Banerjee, D. [Indian Institute of Astrophysics, Bangalore 560 034 (India); Yuan, D. [Institute of Space Science and Applied Technology, Harbin Institute of Technology, Shenzhen 518000 (China)

    2017-09-20

    We observe intensity oscillations along coronal fan loops associated with the active region AR 11428. The intensity oscillations were triggered by blast waves that were generated due to X-class flares in the distant active region AR 11429. To characterize the nature of oscillations, we created time–distance maps along the fan loops and noted that the intensity oscillations at two ends of the loops were out of phase. As we move along the fan loop, the amplitude of the oscillations first decreased and then increased. The out-of-phase nature together with the amplitude variation along the loop implies that these oscillations are very likely to be standing waves. The period of the oscillations is estimated to be ∼27 minutes, damping time to be ∼45 minutes, and phase velocity projected in the plane of sky to be ∼65–83 km s{sup −1}. The projected phase speeds were in the range of the acoustic speed of coronal plasma at about 0.6 MK, which further indicates that these are slow waves. To the best of our knowledge, this is the first report on the existence of the standing slow waves in non-flaring fan loops.

  2. Slow [Na+]i dynamics impacts arrhythmogenesis and spiral wave reentry in cardiac myocyte ionic model

    Science.gov (United States)

    Krogh-Madsen, Trine; Christini, David J.

    2017-09-01

    Accumulation of intracellular Na+ is gaining recognition as an important regulator of cardiac myocyte electrophysiology. The intracellular Na+ concentration can be an important determinant of the cardiac action potential duration, can modulate the tissue-level conduction of excitation waves, and can alter vulnerability to arrhythmias. Mathematical models of cardiac electrophysiology often incorporate a dynamic intracellular Na+ concentration, which changes much more slowly than the remaining variables. We investigated the dependence of several arrhythmogenesis-related factors on [Na+]i in a mathematical model of the human atrial action potential. In cell simulations, we found that [Na+]i accumulation stabilizes the action potential duration to variations in several conductances and that the slow dynamics of [Na+]i impacts bifurcations to pro-arrhythmic afterdepolarizations, causing intermittency between different rhythms. In long-lasting tissue simulations of spiral wave reentry, [Na+]i becomes spatially heterogeneous with a decreased area around the spiral wave rotation center. This heterogeneous region forms a functional anchor, resulting in diminished meandering of the spiral wave. Our findings suggest that slow, physiological, rate-dependent variations in [Na+]i may play complex roles in cellular and tissue-level cardiac dynamics.

  3. Precise measurement and accuracy analysis for determining the fast or slow axis of wave plate

    Science.gov (United States)

    Wang, Guixia; Su, Junhong; Xu, Junqi

    2018-01-01

    A method used for precisely measuring the placement of the fast or slow axis of wave plate is presented. In this method, a test wave plate is placed between a polarizer and an analyzer. With the polarizer and analyzer being rotated to different positions, the intensity of the emergent light is measured and one of the optics principal axes of the test wave plate is marked. Then whether this optics principal axis is a fast or slow axis is measured by checking the state of the emergent light polarization. By taking the method of identifying the intensity value near the inflection point, the error caused by directly searching the extreme value of the light intensity can be avoided and the accuracy of determining axis can also be improved significantly. In addition, the source of the determining axis accuracy, which is +/-0.1° . is also analyzed in detail. With regard to the method, there are no requirements for the wavelength of the light source or the linearity, undercurrent and isotropy of the photoelectric detector. Above all, it can be applied to determining the axis of wave plate with any phase retardation.

  4. Do calcium buffers always slow down the propagation of calcium waves?

    Science.gov (United States)

    Tsai, Je-Chiang

    2013-12-01

    Calcium buffers are large proteins that act as binding sites for free cytosolic calcium. Since a large fraction of cytosolic calcium is bound to calcium buffers, calcium waves are widely observed under the condition that free cytosolic calcium is heavily buffered. In addition, all physiological buffered excitable systems contain multiple buffers with different affinities. It is thus important to understand the properties of waves in excitable systems with the inclusion of buffers. There is an ongoing controversy about whether or not the addition of calcium buffers into the system always slows down the propagation of calcium waves. To solve this controversy, we incorporate the buffering effect into the generic excitable system, the FitzHugh-Nagumo model, to get the buffered FitzHugh-Nagumo model, and then to study the effect of the added buffer with large diffusivity on traveling waves of such a model in one spatial dimension. We can find a critical dissociation constant (K = K(a)) characterized by system excitability parameter a such that calcium buffers can be classified into two types: weak buffers (K ∈ (K(a), ∞)) and strong buffers (K ∈ (0, K(a))). We analytically show that the addition of weak buffers or strong buffers but with its total concentration b(0)(1) below some critical total concentration b(0,c)(1) into the system can generate a traveling wave of the resulting system which propagates faster than that of the origin system, provided that the diffusivity D1 of the added buffers is sufficiently large. Further, the magnitude of the wave speed of traveling waves of the resulting system is proportional to √D1 as D1 --> ∞. In contrast, the addition of strong buffers with the total concentration b(0)(1) > b(0,c)(1) into the system may not be able to support the formation of a biologically acceptable wave provided that the diffusivity D1 of the added buffers is sufficiently large.

  5. Experimental estimation of technology parameters of TWT slow-wave structure elements manufacture

    Directory of Open Access Journals (Sweden)

    Predmirskyi V. S.

    2017-04-01

    Full Text Available During the test of traveling wave tubes it was ascertained the direct dependence of the thermal conductivity of the slow wave structure from accuracy of manufacturing and from porosity of ceramic support rods. It is allowed to define the need to improve the accuracy of their production and the presorting by porosity. In this paper it is solved the problem of fastening of the ceramic rods in the process of processing by coolant instead of adhesive layer. The list of technological parameters and modes of machining support rods held by molecular cohesion forces are defined. The developed system of experiments allowed to determine the processing parameters required for the calculation of the bond strength (due to the liquid layer of the ceramic support rod with a mandrel in the process of machining. This makes possible to determine the technological process parameters of ceramic supporting bars polishing for TWT slow-wave structure. It is shown the possibility of power approach to the estimation of process parameters.

  6. Pilot Study of Propofol-induced Slow Waves as a Pharmacologic Test for Brain Dysfunction after Brain Injury.

    Science.gov (United States)

    Kortelainen, Jukka; Väyrynen, Eero; Huuskonen, Usko; Laurila, Jouko; Koskenkari, Juha; Backman, Janne T; Alahuhta, Seppo; Seppänen, Tapio; Ala-Kokko, Tero

    2017-01-01

    Slow waves (less than 1 Hz) are the most important electroencephalogram signatures of nonrapid eye movement sleep. While considered to have a substantial importance in, for example, providing conditions for single-cell rest and preventing long-term neural damage, a disturbance in this neurophysiologic phenomenon is a potential indicator of brain dysfunction. Since, in healthy individuals, slow waves can be induced with anesthetics, the authors tested the possible association between hypoxic brain injury and slow-wave activity in comatose postcardiac arrest patients (n = 10) using controlled propofol exposure. The slow-wave activity was determined by calculating the low-frequency (less than 1 Hz) power of the electroencephalograms recorded approximately 48 h after cardiac arrest. To define the association between the slow waves and the potential brain injury, the patients' neurologic recovery was then followed up for 6 months. In the patients with good neurologic outcome (n = 6), the low-frequency power of electroencephalogram representing the slow-wave activity was found to substantially increase (mean ± SD, 190 ± 83%) due to the administration of propofol. By contrast, the patients with poor neurologic outcome (n = 4) were unable to generate propofol-induced slow waves. In this experimental pilot study, the comatose postcardiac arrest patients with poor neurologic outcome were unable to generate normal propofol-induced electroencephalographic slow-wave activity 48 h after cardiac arrest. The finding might offer potential for developing a pharmacologic test for prognostication of brain injury by measuring the electroencephalographic response to propofol.

  7. Measurement of the speed and attenuation of the Biot slow wave using a large ultrasonic transmitter

    Science.gov (United States)

    Bouzidi, Youcef; Schmitt, Douglas R.

    2009-08-01

    Two compressional wave modes, a fast P1 and a slow P2, propagate through fluid-saturated porous and permeable media. This contribution focuses on new experimental tests of existing theories describing wave propagation in such media. Updated observations of this P2 mode are obtained through a water-loaded, porous sintered glass bead plate with a novel pair of ultrasonic transducers consisting of a large transmitter and a near-point receiver. The properties of the porous plate are measured in independent laboratory experiments. Waveforms are acquired as a function of the angle of incidence over the range from -50° to +50° with respect to the normal. The porous plate is fully characterized, and the physical properties are used to calculate the wave speeds and attenuations of the P1, the P2, and the shear S waves. Comparisons of theory and observation are further facilitated by numerically modeling the observed waveforms. This modeling method incorporates the frequency and angle of incidence-dependent reflectivity, transmissivity, and transducer edge effects; the modeled waveforms match well those observed. Taken together, this study provides further support for existing poroelastic bulk wave propagation and boundary condition theory. However, observed transmitted P1 and S mode amplitudes could not be adequately described unless the attenuation of the medium's frame was also included. The observed P2 amplitudes could be explained without any knowledge of the solid frame attenuation.

  8. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Full-wave analysis of the high frequency characteristics of the sine waveguide slow-wave structure

    Science.gov (United States)

    Lei, Xia; Wei, Yanyu; Wang, Yuanyuan; Zhou, Qing; Wu, Gangxiong; Ding, Chong; Li, Qian; Zhang, Luqi; Jiang, Xuebing; Gong, Yubin; Wang, Wenxiang

    2017-08-01

    A theoretical model for calculation of the high frequency characteristics of the sine waveguide slow-wave structure (SWS) is proposed. The formulas of dispersion and interaction impedances of the hybrid modes are obtained by combining the Helmholtz equation with the appropriate boundary conditions. Using the full wave analysis method, it is proved that the periodic structures with a half-period shift followed leads to a pairwise closing of passbands characteristic of adjacent mode. The sine waveguide SWS for 0.22THz traveling wave tube (TWT) is chosen as an illustrative example to verify the validity of the theoretical model, and the calculation results of the dispersion curve and interaction impedance curve are consistent with the HFSS simulation results. In addition, the influences of dimensions of sine waveguide on the high frequency characteristics of +1st spatial harmonic wave are investigated by numerical calculation. The study indicates that the appropriate SWS parameters are helpful for improving the bandwidth and increasing output power of TWT.

  10. Full-wave analysis of the high frequency characteristics of the sine waveguide slow-wave structure

    Directory of Open Access Journals (Sweden)

    Xia Lei

    2017-08-01

    Full Text Available A theoretical model for calculation of the high frequency characteristics of the sine waveguide slow-wave structure (SWS is proposed. The formulas of dispersion and interaction impedances of the hybrid modes are obtained by combining the Helmholtz equation with the appropriate boundary conditions. Using the full wave analysis method, it is proved that the periodic structures with a half-period shift followed leads to a pairwise closing of passbands characteristic of adjacent mode. The sine waveguide SWS for 0.22THz traveling wave tube (TWT is chosen as an illustrative example to verify the validity of the theoretical model, and the calculation results of the dispersion curve and interaction impedance curve are consistent with the HFSS simulation results. In addition, the influences of dimensions of sine waveguide on the high frequency characteristics of +1st spatial harmonic wave are investigated by numerical calculation. The study indicates that the appropriate SWS parameters are helpful for improving the bandwidth and increasing output power of TWT.

  11. Slow wave structures integrated with ferromagnetic and ferro-electric thin films for smart RF applications

    Science.gov (United States)

    Rahman, B. M. Farid

    Modern communications systems are following a common trend to increase the operational frequency, level of integration and number of frequency bands. Although 90-95% components in a cell phone are passives which take 80% of the total board area. High performance RF passive components play limited role and are desired towards this technological advancement. Slow wave structure is one of the most promising candidates to design compact RF and mm-Wave passive components. Slow wave structures are the specially designed transmission line realized by placing the alternate narrow and wide signal conductors in order to reduce the physical size of the components. This dissertation reports multiband slow wave structures integrated with ferromagnetic and ferroelectric thin films and their RF applications. A comparative study on different types of coplanar wave-guide (CPW) slow wave structures (SWS) has been demonstrated for the first time. Slow wave structures with various shapes have been investigated and optimized with various signal conductor shapes, ground conductor shapes and pitch of the sections. Novel techniques i.e. the use of the defected ground structure and the different signal conductor length has been implemented to achieve higher slow wave effect with minimum loss. The measured results have shown the reduction of size over 43.47% and 37.54% in the expense of only 0.27dB and 0.102dB insertion loss respectively which can reduce the area of a designed branch line coupler by 68% and 61% accordingly. Permalloy (Py) is patterned on top of the developed SWS for the first time to further increase the slow wave effect and provide tunable inductance value. High frequency applications of Py are limited by its ferro-magnetic resonance frequency since the inductance value decreases beyond that. Sub-micrometer patterning of Py has increased FMR frequency until 6.3GHz and 3.2GHz by introducing the shape anisotropy. For the SWS with patterned Py, the size of the quarter

  12. 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.

  13. Conventional, Bayesian, and Modified Prony's methods for characterizing fast and slow waves in equine cancellous bone

    OpenAIRE

    Groopman, Amber M.; Katz, Jonathan I.; Holland, Mark R.; Fujita, Fuminori; Matsukawa, Mami; Mizuno, Katsunori; Wear, Keith A.; Miller, James G.

    2015-01-01

    Conventional, Bayesian, and the modified least-squares Prony's plus curve-fitting (MLSP + CF) methods were applied to data acquired using 1 MHz center frequency, broadband transducers on a single equine cancellous bone specimen that was systematically shortened from 11.8 mm down to 0.5 mm for a total of 24 sample thicknesses. Due to overlapping fast and slow waves, conventional analysis methods were restricted to data from sample thicknesses ranging from 11.8 mm to 6.0 mm. In contrast, Bayesi...

  14. 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.

  15. Development of slow and fast wave coupling and heating from the C-Stellarator to NSTX

    Directory of Open Access Journals (Sweden)

    Hosea Joel

    2017-01-01

    Full Text Available A historical perspective on key discoveries which contributed to understanding the properties of coupling both slow and fast waves and the effects on plasma heating and current drive will be presented. Important steps made include the demonstration that the Alfven resonance was in fact a mode conversion on the C-stellarator, that toroidal m = -1 eigenmodes were excited in toroidal geometry and impurity influx caused the Z mode on the ST tokamak, that the H minority regime provided strong heating and that 3He minority could be used as well on PLT, that the 2nd harmonic majority tritium regime was viable on TFTR, and that high harmonic fast wave heating was efficient when the SOL losses were avoided on NSTX.

  16. Development of slow and fast wave coupling and heating from the C-Stellarator to NSTX

    Science.gov (United States)

    Hosea, Joel

    2017-10-01

    A historical perspective on key discoveries which contributed to understanding the properties of coupling both slow and fast waves and the effects on plasma heating and current drive will be presented. Important steps made include the demonstration that the Alfven resonance was in fact a mode conversion on the C-stellarator, that toroidal m = -1 eigenmodes were excited in toroidal geometry and impurity influx caused the Z mode on the ST tokamak, that the H minority regime provided strong heating and that 3He minority could be used as well on PLT, that the 2nd harmonic majority tritium regime was viable on TFTR, and that high harmonic fast wave heating was efficient when the SOL losses were avoided on NSTX.

  17. Effects of oral temazepam on slow waves during non-rapid eye movement sleep in healthy young adults: A high-density EEG investigation.

    Science.gov (United States)

    Plante, D T; Goldstein, M R; Cook, J D; Smith, R; Riedner, B A; Rumble, M E; Jelenchick, L; Roth, A; Tononi, G; Benca, R M; Peterson, M J

    2016-03-01

    Slow waves are characteristic waveforms that occur during non-rapid eye movement (NREM) sleep that play an integral role in sleep quality and brain plasticity. Benzodiazepines are commonly used medications that alter slow waves, however, their effects may depend on the time of night and measure used to characterize slow waves. Prior investigations have utilized minimal scalp derivations to evaluate the effects of benzodiazepines on slow waves, and thus the topography of changes to slow waves induced by benzodiazepines has yet to be fully elucidated. This study used high-density electroencephalography (hdEEG) to evaluate the effects of oral temazepam on slow wave activity, incidence, and morphology during NREM sleep in 18 healthy adults relative to placebo. Temazepam was associated with significant decreases in slow wave activity and incidence, which were most prominent in the latter portions of the sleep period. However, temazepam was also associated with a decrease in the magnitude of high-amplitude slow waves and their slopes in the first NREM sleep episode, which was most prominent in frontal derivations. These findings suggest that benzodiazepines produce changes in slow waves throughout the night that vary depending on cortical topography and measures used to characterize slow waves. Further research that explores the relationships between benzodiazepine-induced changes to slow waves and the functional effects of these waveforms is indicated. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. High power microwave source with a three dimensional printed metamaterial slow-wave structure

    Energy Technology Data Exchange (ETDEWEB)

    French, David M.; Shiffler, Don [Air Force Research Laboratory, Directed Energy Directorate, Albuquerque, New Mexico 871117 (United States)

    2016-05-15

    For over the last decade, the concept of metamaterials has led to new approaches for considering the interaction of radiation with complex structures. However, practical manifestations of such a device operating at high power densities have proven difficult to achieve due to the resonant nature of metamaterials and the resultant high electric fields, which place severe constraints on manufacturing the slow wave structures. In this paper, we describe the first experimental manifestation of a high power microwave device utilizing a metallic slow wave structure (metamaterial-like) fabricated using additive manufacturing. The feasibility of utilizing additive manufacturing as a technique for building these relatively complicated structures has thus been demonstrated. The MW class microwave source operates in the C-band and shows frequency tunablility with electron beam voltage. The basic electromagnetic characteristics of this device, the construction using additive manufacturing, and the basic performance as a microwave oscillator are considered. Due to the tunable nature of the device, it shows promise not only as an oscillator but also as a microwave amplifier. Therefore, the dispersive characteristics and a discussion of the anticipated gain is included as it relates to an amplifier configuration.

  19. Cued memory reactivation during slow-wave sleep promotes explicit knowledge of a motor sequence.

    Science.gov (United States)

    Cousins, James N; El-Deredy, Wael; Parkes, Laura M; Hennies, Nora; Lewis, Penelope A

    2014-11-26

    Memories are gradually consolidated after initial encoding, and this can sometimes lead to a transition from implicit to explicit knowledge. The exact physiological processes underlying this reorganization remain unclear. Here, we used a serial reaction time task to determine whether targeted memory reactivation (TMR) of specific memory traces during slow-wave sleep promotes the emergence of explicit knowledge. Human participants learned two 12-item sequences of button presses (A and B). These differed in both cue order and in the auditory tones associated with each of the four fingers (one sequence had four higher-pitched tones). Subsequent overnight sleep was monitored, and the tones associated with one learned sequence were replayed during slow-wave sleep. After waking, participants demonstrated greater explicit knowledge (p = 0.005) and more improved procedural skill (p = 0.04) for the cued sequence relative to the uncued sequence. Furthermore, fast spindles (13.5-15 Hz) at task-related motor regions predicted overnight enhancement in procedural skill (r = 0.71, p = 0.01). Auditory cues had no effect on post-sleep memory performance in a control group who received TMR before sleep. These findings suggest that TMR during sleep can alter memory representations and promote the emergence of explicit knowledge, supporting the notion that reactivation during sleep is a key mechanism in this process. Copyright © 2014 Cousins et al.

  20. High power microwave source with a three dimensional printed metamaterial slow-wave structure.

    Science.gov (United States)

    French, David M; Shiffler, Don

    2016-05-01

    For over the last decade, the concept of metamaterials has led to new approaches for considering the interaction of radiation with complex structures. However, practical manifestations of such a device operating at high power densities have proven difficult to achieve due to the resonant nature of metamaterials and the resultant high electric fields, which place severe constraints on manufacturing the slow wave structures. In this paper, we describe the first experimental manifestation of a high power microwave device utilizing a metallic slow wave structure (metamaterial-like) fabricated using additive manufacturing. The feasibility of utilizing additive manufacturing as a technique for building these relatively complicated structures has thus been demonstrated. The MW class microwave source operates in the C-band and shows frequency tunablility with electron beam voltage. The basic electromagnetic characteristics of this device, the construction using additive manufacturing, and the basic performance as a microwave oscillator are considered. Due to the tunable nature of the device, it shows promise not only as an oscillator but also as a microwave amplifier. Therefore, the dispersive characteristics and a discussion of the anticipated gain is included as it relates to an amplifier configuration.

  1. Slow-wave disruption enhances the accessibility of positive memory traces.

    Science.gov (United States)

    Goldschmied, Jennifer R; Cheng, Philip; Kim, Hyang Sook; Casement, Melynda; Armitage, Roseanne; Deldin, Patricia J

    2015-11-01

    The purpose of this study was to explore the effects of slow-wave disruption on positive and negative word recognition in a sample of healthy control participants and those with major depressive disorder. Prior to sleep, participants learned a set of emotional and neutral words during an encoding task by responding whether or not the word described them. Following baseline sleep, participants underwent one night of selective slow-wave disruption by auditory stimuli. Accuracy and reaction time to a recognition word set, including both positive and negative words, was assessed in the morning. Repeated-measures ANOVA revealed a significant interaction between word valence and condition, with positive words recognized significantly faster than negative words after disruption, in only healthy control participants. There were no significant results in those with major depressive disorder, or with regard to accuracy. These results may add to the increasing body of literature suggesting a hedonic bias to positive stimuli following sleep disruption. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Attachment dismissal predicts frontal slow-wave ERPs during rejection by unfamiliar peers.

    Science.gov (United States)

    White, Lars O; Wu, Jia; Borelli, Jessica L; Rutherford, Helena J V; David, Daryn H; Kim-Cohen, Julia; Mayes, Linda C; Crowley, Michael J

    2012-08-01

    Attachment representations are thought to provide a cognitive-affective template, guiding the way individuals interact with unfamiliar social partners. To examine the neural correlates of this process, we sampled event-related potentials (ERPs) during exclusion by unfamiliar peers to differentiate insecure-dismissing from securely attached youth, as indexed by the child attachment interview. Thirteen secure and 10 dismissing 11- to 15-year-olds were ostensibly connected with two peers via the Internet to play a computerized ball-toss game. Actually, peers were computer generated, first distributing the ball evenly, but eventually excluding participants. Afterward children rated their distress. As in previous studies, distress was related to a negative left frontal slow wave (500-900 ms) during rejection, a waveform implicated in negative appraisals and less approach motivation. Though attachment classifications were comparable in frontal ERPs and distress, an attachment-related dismissal dimension predicted a negative left frontal slow wave during rejection, suggesting that high dismissal potentially involves elevated anticipation of rejection. As expected, dismissal and self-reported distress were uncorrelated. Yet, a new approach to quantifying the dissociation between self-reports and rejection-related ERPs revealed that dismissal predicted underreporting of distress relative to ERPs. Our findings imply that evaluations and regulatory strategies linked to attachment generalize to distressing social contexts in early adolescence.

  3. 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)

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

    2017-02-01

    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. 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. 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. Georg Thieme Verlag KG Stuttgart · New York.

  4. Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi; Wang, Linghua [School of Earth and Space Sciences, Peking University, Beijing, 100871, China, E-mail: jshept@gmail.com (China); Zhang, Lei [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Vocks, Christian [Leibniz-Institut für Astrophysik Potsdam, 14482, Potsdam (Germany); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, 24118 Kiel (Germany); Peter, Hardi [Max Plank Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen (Germany)

    2016-03-25

    We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data of the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the “wave + beam flow” kinetic model may be a viable interpretation for the PIDs observed in the solar corona.

  5. 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.

  6. 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...

  7. Cortical deactivation induced by visual stimulation in human slow-wave sleep

    DEFF Research Database (Denmark)

    Born, Alfred Peter; Law, Ian; Lund, Torben E

    2002-01-01

    . It is unresolved whether this negative BOLD response pattern is of developmental neurobiological origin particular to a given age or to a general effect of sleep or sedative drugs. To further elucidate this issue, we used fMRI and positron emission tomography (PET) to study the brain activation pattern during...... and polysomnographically verified slow-wave sleep in a separate group of six subjects using H(2)(15)O PET measures of the regional cerebral blood flow (rCBF). This decrease was more rostro-dorsal compared to the relative rCBF increase along the calcarine sulcus found during visual stimulation in the awake state....... This study reconfirms the previously described paradoxical stimulation-correlated negative BOLD signal change in the rostro-medial occipital cortex, expanding this response mode to an age spectrum ranging from the newborn to the adult. Further, the use of complementary brain mapping techniques suggests...

  8. Stationary waves and slow cloud features challenge Venus's night side superrotation

    Science.gov (United States)

    Peralta, J.; Hueso, R.; Sánchez-Lavega, A.; Lee, Y. J.; García-Muñoz, A.; Kouyama, T.; Sagawa, H.; Sato, T. M.; Piccioni, G.; Tellmann, S.; Satoh, T.

    2017-09-01

    We present the first global measurements of the night side circulation of Venus at the upper cloud level from the tracking of individual features in thermal emission images at 3.8 and 5.0 μm during 2006-2008 (Venus Express/VIRTIS) and 2015 (IRTF/SpeX). The zonal motions range from -110 to -60 m/s, consistent with those found for the dayside but with larger dispersion6. Slow motions (-50 to -20 m/s) are also found and may indicate temporal changes in the vertical structure of the superrotation. Abundant stationary wave patterns with zonal speeds from -10 to +10 m/s clearly dominate the night upper clouds.

  9. Effects of Tiagabine on Slow Wave Sleep and Arousal Threshold in Patients With Obstructive Sleep Apnea.

    Science.gov (United States)

    Taranto-Montemurro, Luigi; Sands, Scott A; Edwards, Bradley A; Azarbarzin, Ali; Marques, Melania; de Melo, Camila; Eckert, Danny J; White, David P; Wellman, Andrew

    2017-02-01

    Obstructive sleep apnea (OSA) severity is markedly reduced during slow-wave sleep (SWS) even in patients with a severe disease. The reason for this improvement is uncertain but likely relates to non-anatomical factors (i.e. reduced arousability, chemosensitivity, and increased dilator muscle activity). The anticonvulsant tiagabine produces a dose-dependent increase in SWS in subjects without OSA. This study aimed to test the hypothesis that tiagabine would reduce OSA severity by raising the overall arousal threshold during sleep. After a baseline physiology night to assess patients' OSA phenotypic traits, a placebo-controlled, double-blind, crossover trial of tiagabine 12 mg administered before sleep was performed in 14 OSA patients. Under each condition, we assessed the effects on sleep and OSA severity using standard clinical polysomnography. Tiagabine increased slow-wave activity (SWA) of the electroencephalogram (1-4 Hz) compared to placebo (1.8 [0.4] vs. 2.0 [0.5] LogμV2, p = .04) but did not reduce OSA severity (apnea-hypopnea index [AHI] 41.5 [20.3] vs. 39.1 [16.5], p > .5). SWS duration (25 [20] vs. 26 [43] mins, p > .5) and arousal threshold (-26.5 [5.0] vs. -27.6 [5.1] cmH2O, p = .26) were also unchanged between nights. Tiagabine modified sleep microstructure (increase in SWA) but did not change the duration of SWS, OSA severity, or arousal threshold in this group of OSA patients. Based on these findings, tiagabine should not be considered as a therapeutic option for OSA treatment.

  10. Output characteristics of a 0.14 THz dual sheet beam backward wave oscillator based on a hole-grating slow wave structure

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Xiaopin; Yang, Ziqiang; Shi, Zongjun; Lan, Feng; Zeng, Hongxin; Zhang, Ting [Terahertz Research Center, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-07-15

    A novel backward wave oscillator (BWO) based on a hole-grating slow wave structure is proposed as a dual sheet beam millimeter wave radiation source. In this paper, we focus on the output characteristics of a 0.14 THz hole-grating BWO. The output characteristics of the hole-grating BWO, the conventional single-beam grating BWO, and the dual-beam grating BWO are contrasted in detail. 3-D particle-in-cell results indicate that the hole-grating slow wave structure can help to increase the maximum output power as well as lower the operating current density. Meanwhile, the hole-grating BWO shows good insensitivity to the differences between two sheet electron beams. These characteristics make the hole-grating BWO feasible to be a stable millimeter wave radiation source with higher output power.

  11. Herbal extracts modulate the amplitude and frequency of slow waves in circular smooth muscle of mouse small intestine.

    Science.gov (United States)

    Storr, M; Sibaev, A; Weiser, D; Kelber, O; Schirra, J; Goke, B; Allescher, H D

    2004-01-01

    Herbal preparations like STW 5 (Iberogast) are widely used drugs in the treatment of dyspepsia and motility-related disorders of the gastrointestinal tract. STW 5 is a phytotherapeutic agent consisting of a fixed mixture of 9 individual plant extracts. The electrophysiological mechanisms of action of STW 5 remain obscure. The aim of the present study was to investigate whether herbal extracts influence electrophysiological parameters of the small intestine. For this purpose, the resting membrane potential (RMP) and the slow wave rhythmicity of smooth muscle cells of mouse small intestine were observed. Intracellular recordings of smooth muscle cells of the circular muscle layer of mouse small intestine were performed using standard microelectrode techniques. After dissection of the mucosa, the small intestine was placed in an organ bath and a microelectrode was applied on a circular smooth muscle cell. The RMP and the amplitude of slow waves were measured in millivolts. The RMP of smooth muscle cells was -59 +/- 1.3 mV. This RMP was significantly depolarized by STW 5 (9.6 +/- 1.6 mV); the depolarizing effects can be mainly attributed to the constituents of matricariae flos, angelicae radix and chelidonii herba. The basal frequency of small intestinal slow waves was 39.5 +/- 1.4 min(-1) and the amplitude was 23.1 +/- 0.9 mV. STW 5 significantly reduced the amplitude and frequency of the slow waves (11.7 +/- 0.8 mV; 33.5 +/- 3.4 min(-1)). This effect on slow waves represents the sum of the effects of the 9 phytoextracts. Whereas angelicae radix and matricariae flos completely blocked slow wave activity, Iberis amara increased the frequency and amplitude, chelidonii herba reduced the frequency and amplitude of the slow waves, mentae piperitae folium reduced the frequency and left amplitude unchanged and liquiritae radix, carvi fructus and melissae folium had no effects. Herbal extracts cause changes in smooth muscle RMP and slow wave rhythmicity, up to reversible

  12. Eye Movement Desensitization and Reprocessing and Slow Wave Sleep: A Putative Mechanism of Action.

    Science.gov (United States)

    Pagani, Marco; Amann, Benedikt L; Landin-Romero, Ramon; Carletto, Sara

    2017-01-01

    Eye Movement Desensitization and Reprocessing (EMDR) is considered highly efficacious for the treatment of Post-traumatic Stress Disorder and has proved to be a valid treatment approach with a wide range of applications. However, EMDR's mechanisms of action is not yet fully understood. This is an active area of clinical and neurophysiological research, and several different hypotheses have been proposed. This paper discusses a conjecture which focuses on the similarity between the delta waves recorded by electroencephalography during Slow Wave Sleep (SWS) and those registered upon typical EMDR bilateral stimulation (eye movements or alternate tapping) during recurrent distressing memories of an emotionally traumatic event. SWS appears to have a key role in memory consolidation and in the reorganization of distant functional networks, as well as Eye Movements seem to reduce traumatic episodic memory and favor the reconsolidation of new associated information. The SWS hypothesis may put forward an explanation of how EMDR works, and is discussed also in light of other theories and neurobiological findings.

  13. Eye Movement Desensitization and Reprocessing and Slow Wave Sleep: A Putative Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Marco Pagani

    2017-11-01

    Full Text Available Eye Movement Desensitization and Reprocessing (EMDR is considered highly efficacious for the treatment of Post-traumatic Stress Disorder and has proved to be a valid treatment approach with a wide range of applications. However, EMDR’s mechanisms of action is not yet fully understood. This is an active area of clinical and neurophysiological research, and several different hypotheses have been proposed. This paper discusses a conjecture which focuses on the similarity between the delta waves recorded by electroencephalography during Slow Wave Sleep (SWS and those registered upon typical EMDR bilateral stimulation (eye movements or alternate tapping during recurrent distressing memories of an emotionally traumatic event. SWS appears to have a key role in memory consolidation and in the reorganization of distant functional networks, as well as Eye Movements seem to reduce traumatic episodic memory and favor the reconsolidation of new associated information. The SWS hypothesis may put forward an explanation of how EMDR works, and is discussed also in light of other theories and neurobiological findings.

  14. The Role of Non-Rapid Eye Movement Slow-Wave Activity in Prefrontal Metabolism across Young and Middle Age Adults

    OpenAIRE

    Wilckens, K.A.; Aizenstein, H J; Nofzinger, E.A.; James, J. A.; Hasler, B.P.; Rosario-Rivera, B.L.; Franzen, P; Germain, A.; Hall, M. H.; Kupfer, D.J.; Price, J C.; Siegle, G.J.; Buysse, D. J.

    2016-01-01

    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...

  15. Circulating motilin, ghrelin, and GLP-1 and their correlations with gastric slow waves in patients with chronic kidney disease.

    Science.gov (United States)

    Wu, Gao-Jue; Cai, Xu-Dong; Xing, Jie; Zhong, Guang-Hui; Chen, Jiande D Z

    2017-08-01

    Patients with chronic kidney disease (CKD) commonly complain upper gastrointestinal (GI) symptoms, especially anorexia. Hemodialysis (HD) has been noted to improve GI symptoms; however, the underlying mechanisms are unclear. This study was designed 1) to study effects of HD on GI symptoms and gastric slow waves; and 2) to investigate possible roles of ghrelin and glucagon-like peptide-1 (GLP-1): the study recruited 13 healthy controls, 20 CKD patients without HD (CKD group), and 18 CKD patients with HD (HD group). Dyspeptic symptoms, autonomic functions, gastric slow waves, and plasma level of ghrelin and GLP-1 were analyzed. First, the CKD patients with HD showed markedly lower scores of anorexia (0.6 ± 0.2 vs. 3.2 ± 0.4, P waves, compared with controls. Third, the CKD group exhibited a significantly lower ghrelin level compared with the HD group (26.8 ± 0.9 vs. 34.1 ± 2.3 ng/l, P waves was positively correlated with ghrelin (r = 0.385, P = 0.019) but negatively correlated with GLP-1 (r = -0.558, P waves in CKD patients. An increase in ghrelin and a decrease in GLP-1 might be involved in the HD-induced improvement in gastric slow waves. Copyright © 2017 the American Physiological Society.

  16. Characterization of sleep need dissipation using EEG based slow-wave activity analysis in two age groups

    NARCIS (Netherlands)

    Garcia-Molina, G.; Baehr, K.; Steele, B.; Tsoneva, T.K.; Pfundtner, S.; Mahadevan, A.; Papas, N.; Riedner, B.; Tononi, G.; White, D.

    2017-01-01

    Introduction: In the two-process model of sleep regulation, slow-wave activity (SWA, EEG power in the 0.5–4 Hz band) is a direct indicator of sleep need. SWA builds up during NREM sleep, declines before the onset of REM sleep, remains low during REM and the level of increase in successive NREM

  17. Costs of storing colour and complex shape in visual working memory: Insights from pupil size and slow waves.

    Science.gov (United States)

    Kursawe, Michael A; Zimmer, Hubert D

    2015-06-01

    We investigated the impact of perceptual processing demands on visual working memory of coloured complex random polygons during change detection. Processing load was assessed by pupil size (Exp. 1) and additionally slow wave potentials (Exp. 2). Task difficulty was manipulated by presenting different set sizes (1, 2, 4 items) and by making different features (colour, shape, or both) task-relevant. Memory performance in the colour condition was better than in the shape and both condition which did not differ. Pupil dilation and the posterior N1 increased with set size independent of type of feature. In contrast, slow waves and a posterior P2 component showed set size effects but only if shape was task-relevant. In the colour condition slow waves did not vary with set size. We suggest that pupil size and N1 indicates different states of attentional effort corresponding to the number of presented items. In contrast, slow waves reflect processes related to encoding and maintenance strategies. The observation that their potentials vary with the type of feature (simple colour versus complex shape) indicates that perceptual complexity already influences encoding and storage and not only comparison of targets with memory entries at the moment of testing. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. 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

  19. Predictability of arousal in mouse slow wave sleep by accelerometer data

    Science.gov (United States)

    Lopes, Sergio Roberto; Prado, Thiago Lima; Lobao-Soares, Bruno; do Nascimento, George C.; Fontenele-Araujo, John; Corso, Gilberto

    2017-01-01

    Arousals can be roughly characterized by punctual intrusions of wakefulness into sleep. In a standard perspective, using human electroencephalography (EEG) data, arousals are associated to slow-wave rhythms and K-complex brain activity. The physiological mechanisms that give rise to arousals during sleep are not yet fully understood. Moreover, subtle body movement patterns, which may characterize arousals both in human and in animals, are usually not detectable by eye perception and are not in general present in sleep studies. In this paper, we focus attention on accelerometer records (AR) to characterize and predict arousal during slow wave sleep (SWS) stage of mice. Furthermore, we recorded the local field potentials (LFP) from the CA1 region in the hippocampus and paired with accelerometer data. The hippocampus signal was also used here to identify the SWS stage. We analyzed the AR dynamics of consecutive arousals using recurrence technique and the determinism (DET) quantifier. Recurrence is a fundamental property of dynamical systems, which can be exploited to characterize time series properties. The DET index evaluates how similar are the evolution of close trajectories: in this sense, it computes how accurate are predictions based on past trajectories. For all analyzed mice in this work, we observed, for the first time, the occurrence of a universal dynamic pattern a few seconds that precedes the arousals during SWS sleep stage based only on the AR signal. The predictability success of an arousal using DET from AR is nearly 90%, while similar analysis using LFP of hippocampus brain region reveal 88% of success. Noteworthy, our findings suggest an unique dynamical behavior pattern preceding an arousal of AR data during sleep. Thus, the employment of this technique applied to AR data may provide useful information about the dynamics of neuronal activities that control sleep-waking switch during SWS sleep period. We argue that the predictability of arousals

  20. Predictability of arousal in mouse slow wave sleep by accelerometer data.

    Science.gov (United States)

    Lima, Gustavo Zampier Dos Santos; Lopes, Sergio Roberto; Prado, Thiago Lima; Lobao-Soares, Bruno; do Nascimento, George C; Fontenele-Araujo, John; Corso, Gilberto

    2017-01-01

    Arousals can be roughly characterized by punctual intrusions of wakefulness into sleep. In a standard perspective, using human electroencephalography (EEG) data, arousals are associated to slow-wave rhythms and K-complex brain activity. The physiological mechanisms that give rise to arousals during sleep are not yet fully understood. Moreover, subtle body movement patterns, which may characterize arousals both in human and in animals, are usually not detectable by eye perception and are not in general present in sleep studies. In this paper, we focus attention on accelerometer records (AR) to characterize and predict arousal during slow wave sleep (SWS) stage of mice. Furthermore, we recorded the local field potentials (LFP) from the CA1 region in the hippocampus and paired with accelerometer data. The hippocampus signal was also used here to identify the SWS stage. We analyzed the AR dynamics of consecutive arousals using recurrence technique and the determinism (DET) quantifier. Recurrence is a fundamental property of dynamical systems, which can be exploited to characterize time series properties. The DET index evaluates how similar are the evolution of close trajectories: in this sense, it computes how accurate are predictions based on past trajectories. For all analyzed mice in this work, we observed, for the first time, the occurrence of a universal dynamic pattern a few seconds that precedes the arousals during SWS sleep stage based only on the AR signal. The predictability success of an arousal using DET from AR is nearly 90%, while similar analysis using LFP of hippocampus brain region reveal 88% of success. Noteworthy, our findings suggest an unique dynamical behavior pattern preceding an arousal of AR data during sleep. Thus, the employment of this technique applied to AR data may provide useful information about the dynamics of neuronal activities that control sleep-waking switch during SWS sleep period. We argue that the predictability of arousals

  1. Predictability of arousal in mouse slow wave sleep by accelerometer data.

    Directory of Open Access Journals (Sweden)

    Gustavo Zampier Dos Santos Lima

    Full Text Available Arousals can be roughly characterized by punctual intrusions of wakefulness into sleep. In a standard perspective, using human electroencephalography (EEG data, arousals are associated to slow-wave rhythms and K-complex brain activity. The physiological mechanisms that give rise to arousals during sleep are not yet fully understood. Moreover, subtle body movement patterns, which may characterize arousals both in human and in animals, are usually not detectable by eye perception and are not in general present in sleep studies. In this paper, we focus attention on accelerometer records (AR to characterize and predict arousal during slow wave sleep (SWS stage of mice. Furthermore, we recorded the local field potentials (LFP from the CA1 region in the hippocampus and paired with accelerometer data. The hippocampus signal was also used here to identify the SWS stage. We analyzed the AR dynamics of consecutive arousals using recurrence technique and the determinism (DET quantifier. Recurrence is a fundamental property of dynamical systems, which can be exploited to characterize time series properties. The DET index evaluates how similar are the evolution of close trajectories: in this sense, it computes how accurate are predictions based on past trajectories. For all analyzed mice in this work, we observed, for the first time, the occurrence of a universal dynamic pattern a few seconds that precedes the arousals during SWS sleep stage based only on the AR signal. The predictability success of an arousal using DET from AR is nearly 90%, while similar analysis using LFP of hippocampus brain region reveal 88% of success. Noteworthy, our findings suggest an unique dynamical behavior pattern preceding an arousal of AR data during sleep. Thus, the employment of this technique applied to AR data may provide useful information about the dynamics of neuronal activities that control sleep-waking switch during SWS sleep period. We argue that the predictability

  2. 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.

  3. Diagnosis of Electrical Status Epilepticus During Slow-Wave Sleep With 100 Seconds of Sleep.

    Science.gov (United States)

    Weber, Amanda B; Albert, Dara V; Yin, Han; Held, Timothy P; Patel, Anup D

    2017-01-01

    Strategies for diagnosing electrical status epilepticus during slow-wave sleep (ESES) vary among interpreting neurologists. Our aim was to evaluate if the spike-wave index (SWI) for the first 100 seconds of sleep is reflective of the SWI when compared with a conventional method. We reviewed EEGs from 2005 to 2011 that were considered diagnostic of ESES based on unspecified methods. The SWI for the first nonrapid eye movement sleep cycle (long method) was calculated by two neurophysiologists. Two different neurophysiologists calculated SWI for the first 100 seconds of sleep (short method). For the purposes of this study, ESES was defined as an SWI of >85%. The two SWI scores were compared. Fourteen EEGs were reviewed. Despite being considered by the initial interpreter as diagnostic of ESES, only 4 of the studies had an SWI of >85% based on each of the methods. For a diagnosis of ESES, the sensitivity of the short method is 80% and the specificity is 89%. Wilcoxon signed rank test was used to compare the long and short methods. A P value of 0.70 indicates no significant difference between the methods. Additionally, the Spearman correlation coefficient is 0.553 (P = 0.04), indicating moderate correlation between the methods. The SWI for the first 100 seconds of nonrapid eye movement sleep is predictive of the SWI for the entire first sleep cycle with a good sensitivity and specificity in our cohort. This suggests an alternative method for diagnosing ESES, which is comparable to analysis of a full night of sleep.

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

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    Chuang, Kuo-Chih, E-mail: chuangkc@zju.edu.cn; Zhang, Zhi-Qiang; Wang, Hua-Xin

    2016-12-09

    Highlights: • Slow waves around the defect modes in a phononic crystal beam are validated. • A fiber Bragg grating displacement sensing system can measure the defect mode. • The defect mode is analyzed by a transfer matrix method with a supercell technique. - Abstract: 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.

  5. Ultrasound shear wave elastography helps discriminate low-grade from high-grade bowel wall fibrosis in ex vivo human intestinal specimens.

    Science.gov (United States)

    Dillman, Jonathan R; Stidham, Ryan W; Higgins, Peter D R; Moons, David S; Johnson, Laura A; Keshavarzi, Nahid R; Rubin, Jonathan M

    2014-12-01

    To determine whether bowel wall fibrosis can be detected in freshly resected human intestinal specimens based on ultrasound-derived shear wave speed. Seventeen intact (>3-cm) bowel segments (15 small and 2 large intestine) from 12 patients with known or suspected inflammatory bowel disease were procured immediately after surgical resection. Ultrasound shear wave elastography of the bowel wall was performed by two methods (Virtual Touch Quantification [VTQ] and Virtual Touch-IQ [VT-IQ]; Siemens Medical Solutions USA, Inc, Mountain View, CA). Eighteen short-axis shear wave speed measurements were acquired from each specimen: 3 from the 9-, 12-, and 3-o'clock locations for each method. Imaging was performed in two areas for specimens greater than 10 cm in length (separated by ≥5 cm). A gastrointestinal pathologist scored correlative histologic slides for inflammation and fibrosis. Differences in mean shear wave speed between bowel segments with low and high inflammation/fibrosis scores were assessed by a Student t test. Receiver operating characteristic curve analysis was performed. High-fibrosis score (n = 11) bowel segments had a significantly greater mean shear wave speed than low-fibrosis score (n = 6) bowel segments (mean ± SD: VTQ, 1.59 ± 0.37 versus 1.18 ± 0.08 m/s; P= .004; VT-IQ, 1.87 ± 0.44 versus 1.50 ± 0.26 m/s; P= .049). There was no significant difference in mean shear wave speed between high-and low-inflammation score bowel segments (P > .05 for both VTQ and VT-IQ). Receiver operating characteristic curves showed areas under the curve of 0.91 (95% confidence interval, 0.67-0.99) for VTQ and 0.77 (95% confidence interval, 0.51-0.94) for VT-IQ in distinguishing low-from high-fibrosis score bowel segments. Ex vivo bowel wall shear wave speed measurements increase when transmural intestinal fibrosis is present. © 2013 by the American Institute of Ultrasound in Medicine.

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

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    Reto Huber

    2007-03-01

    Full Text Available 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.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.These results provide direct evidence for a link between plastic changes and the local regulation of sleep need.

  7. Experimental Testing of a Metamaterial Slow Wave Structure for High-Power Microwave Generation

    Science.gov (United States)

    Shipman, K.; Prasad, S.; Andreev, D.; Fisher, D. M.; Reass, D. B.; Schamiloglu, E.; Gilmore, M.

    2017-10-01

    A high-power L band source has been developed using a metamaterial (MTM) to produce a double negative slow wave structure (SWS) for interaction with an electron beam. The beam is generated by a 700 kV, 6 kA short pulse (10 ns) accelerator. The design of the SWS consists of a cylindrical waveguide, loaded with alternating split-rings that are arrayed axially down the waveguide. The beam is guided down the center of the rings, where electrons interact with the MTM-SWS producing radiation. Power is extracted axially via a circular waveguide, and radiated by a horn antenna. Microwaves are characterized by an external detector placed in a waveguide. Mode characterization is performed using a neon bulb array. The bulbs are lit by the electric field, resulting in an excitation pattern that resembles the field pattern. This is imaged using an SLR camera. The MTM structure has electrically small features so breakdown is a concern. In addition to high speed cameras, a fiber-optic-fed, sub-ns photomultiplier tube array diagnostic has been developed and used to characterize breakdown light. Work supported by the Air Force Office of Scientific Research, MURI Grant FA9550-12-1-0489.

  8. β-amyloid disrupts human NREM slow waves and related hippocampus-dependent memory consolidation.

    Science.gov (United States)

    Mander, Bryce A; Marks, Shawn M; Vogel, Jacob W; Rao, Vikram; Lu, Brandon; Saletin, Jared M; Ancoli-Israel, Sonia; Jagust, William J; Walker, Matthew P

    2015-07-01

    Independent evidence associates β-amyloid pathology with both non-rapid eye movement (NREM) sleep disruption and memory impairment in older adults. However, whether the influence of β-amyloid pathology on hippocampus-dependent memory is, in part, driven by impairments of NREM slow wave activity (SWA) and associated overnight memory consolidation is unknown. Here we show that β-amyloid burden in medial prefrontal cortex (mPFC) correlates significantly with the severity of impairment in NREM SWA generation. Moreover, reduced NREM SWA generation was further associated with impaired overnight memory consolidation and impoverished hippocampal-neocortical memory transformation. Furthermore, structural equation models revealed that the association between mPFC β-amyloid pathology and impaired hippocampus-dependent memory consolidation was not direct, but instead statistically depended on the intermediary factor of diminished NREM SWA. By linking β-amyloid pathology with impaired NREM SWA, these data implicate sleep disruption as a mechanistic pathway through which β-amyloid pathology may contribute to hippocampus-dependent cognitive decline in the elderly.

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

    Science.gov (United States)

    Tesler, Noemi; Gerstenberg, Miriam; Franscini, Maurizia; Jenni, Oskar G; Walitza, Susanne; Huber, Reto

    2016-01-01

    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.

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

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    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

  11. Targeted memory reactivation during slow wave sleep facilitates emotional memory consolidation.

    Science.gov (United States)

    Cairney, Scott A; Durrant, Simon J; Hulleman, Johan; Lewis, Penelope A

    2014-04-01

    To investigate the mechanisms by which auditory targeted memory reactivation (TMR) during slow wave sleep (SWS) influences the consolidation of emotionally negative and neutral memories. Each of 72 (36 negative, 36 neutral) picture-location associations were encoded with a semantically related sound. During a subsequent nap, half of the sounds were replayed in SWS, before picture-location recall was examined in a final test. Manchester Sleep Laboratory, University of Manchester. 15 adults (3 male) mean age = 20.40 (standard deviation ± 3.07). TMR with auditory cues during SWS. Performance was assessed by memory accuracy and recall response times (RTs). Data were analyzed with a 2 (sound: replayed/not replayed) × 2 (emotion: negative/neutral) repeated measures analysis of covariance with SWS duration, and then SWS spindles, as the mean-centered covariate. Both analyses revealed a significant three-way interaction for RTs but not memory accuracy. Critically, SWS duration and SWS spindles predicted faster memory judgments for negative, relative to neutral, picture locations that were cued with TMR. TMR initiates an enhanced consolidation process during subsequent SWS, wherein sleep spindles mediate the selective enhancement of reactivated emotional memories.

  12. Effect of conditioned stimulus exposure during slow wave sleep on fear memory extinction in humans.

    Science.gov (United States)

    He, Jia; Sun, Hong-Qiang; Li, Su-Xia; Zhang, Wei-Hua; Shi, Jie; Ai, Si-Zhi; Li, Yun; Li, Xiao-Jun; Tang, Xiang-Dong; Lu, Lin

    2015-03-01

    Repeated exposure to a neutral conditioned stimulus (CS) in the absence of a noxious unconditioned stimulus (US) elicits fear memory extinction. The aim of the current study was to investigate the effects of mild tone exposure (CS) during slow wave sleep (SWS) on fear memory extinction in humans. The healthy volunteers underwent an auditory fear conditioning paradigm on the experimental night, during which tones served as the CS, and a mild shock served as the US. They were then randomly assigned to four groups. Three groups were exposed to the CS for 3 or 10 min or an irrelevant tone (control stimulus, CtrS) for 10 min during SWS. The fourth group served as controls and was not subjected to any interventions. All of the subjects completed a memory test 4 h after SWS-rich stage to evaluate the effect on fear extinction. Moreover, we conducted similar experiments using an independent group of subjects during the daytime to test whether the memory extinction effect was specific to the sleep condition. Ninety-six healthy volunteers (44 males) aged 18-28 y. Participants exhibited undisturbed sleep during 2 consecutive nights, as assessed by sleep variables (all P > 0.05) from polysomnographic recordings and power spectral analysis. Participants who were re-exposed to the 10 min CS either during SWS and wakefulness exhibited attenuated fear responses (wake-10 min CS, P memory extinction without altering sleep profiles. © 2015 Associated Professional Sleep Societies, LLC.

  13. Implications of slow waves and shifting epileptiform discharges in Angelman syndrome.

    Science.gov (United States)

    Yum, Mi-Sun; Lee, Eun Hye; Kim, Joo-Hyun; Ko, Tae-Sung; Yoo, Han-Wook

    2013-03-01

    Angelman syndrome is a genetic syndrome resulted from a lack of UBE3A gene expression of the maternally inherited abnormalities of chromosome 15q11-q13. About 90% of patients with Angelman syndrome experience epilepsy and its distinctive electroencephalographic changes. Epilepsy predominates in childhood, but may persist in adulthood. The seizure types may be quite varied and sometimes difficult to control. We retrospectively reviewed and analyzed data of 18 patients with genetically and clinically confirmed Angelman syndrome at Asan Medical Center. An analysis of 53 electroencephalography (EEG) records from 18 patients showed that diffuse slow-wave background patterns were significantly associated with uncontrolled periods of epilepsy. Moreover, epileptiform discharges tended to shift from posterior to anterior head regions over time after an initial normal pattern at a young age. Children with Angelman syndrome follow general developmental patterns, with specific patterns of EEG reflecting the maturational pattern of the brain and epileptic activity. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  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. Sex differences in slow-wave electroencephalographic activity (SWA in adolescent depression

    Directory of Open Access Journals (Sweden)

    Robert Hoffmann

    2012-01-01

    Full Text Available Sleep disturbance, present in more than 90% of major depressive disorder (MDD patients, are moderated by sex in adult MDD. In particular, slow-wave electroencephalographic activity (SWA; 0.5-4 Hz accumulation is low and dissipation impaired. This SWA abnormality in depressed adult males does not change with age, suggesting that SWA abnormality appears at early ages. The present study evaluated sex differences in SWA in adolescents with MDD compared to healthy controls. We evaluated regularized sleep-wake schedules at home for 5-7 days, followed by two consecutive nights of sleep EEG recording. The study included 104 participants, 52 symptomatic and depressed subjects (MDD: 20 males and 32 females and 52 healthy controls (HC: 20 males and 32 females, aged 13-18 years. SWA power and dissipation, and duration and latencies to each Non-Rapid Eye Movement (NREM sleep period were calculated for each group. Results showed that SWA accumulation in the first NREM period was lower and its dissipation across the night more irregular in MDD males compared to HC males (P<0.009. By contrast, SWA was equivalent in MDD and HC females. In conclusion, as reported in adult MDD, the accumulation and dissipation of SWA was abnormal in depressed adolescents, but only in males. SWA abnormalities in adolescent MDD may relate to different depressive symptoms in females and males. These results underscore the need to develop sex-specific therapies to enhance and restore SWA in depressed adolescents

  16. Odor cueing during slow-wave sleep benefits memory independently of low cholinergic tone.

    Science.gov (United States)

    Klinzing, Jens G; Kugler, Sabine; Soekadar, Surjo R; Rasch, Björn; Born, Jan; Diekelmann, Susanne

    2018-01-01

    Sleep-dependent memory consolidation depends on the concerted reactivation of memories in the hippocampo-neocortical system. The communication of reactivated information from the hippocampus to the neocortex is assumed to be enabled by low levels of acetylcholine, particularly during slow-wave sleep (SWS). Recent studies suggest that the reactivation of memories does not only occur spontaneously but can also be externally triggered by re-presenting learning-associated cues during sleep. Here we investigated whether the beneficial effect of cued memory reactivation during sleep depends on similar mechanisms as spontaneous reactivation, and specifically on low cholinergic tone. In two experimental nights, healthy volunteers learned a visuo-spatial memory task in the presence of an odor before going to sleep for 40 min. In one night, subjects were presented with the odor again during SWS, whereas in the other night they received an odorless vehicle. In half of the subjects, the availability of acetylcholine during sleep was increased by administering the acetylcholine-esterase inhibitor physostigmine. Contrary to our hypothesis, increased cholinergic tone during sleep did not abolish the beneficial effect of odor cueing: memory performance was better after odor cueing compared to odorless vehicle, independent of physostigmine or placebo administration. This finding challenges the assumption that odor-cued and spontaneous memory reactivation rely on the same neuropharmacological mechanisms.

  17. 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).

  18. 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. © 2016 European Sleep Research Society.

  19. "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…

  20. Reduced Slow-Wave Rebound during Daytime Recovery Sleep in Middle-Aged Subjects

    Science.gov (United States)

    Lafortune, Marjolaine; Gagnon, Jean-François; Latreille, Véronique; Vandewalle, Gilles; Martin, Nicolas; Filipini, Daniel; Doyon, Julien; Carrier, Julie

    2012-01-01

    Cortical synchronization during NREM sleep, characterized by electroencephalographic slow waves (SW 75 µV), is strongly related to the number of hours of wakefulness prior to sleep and to the quality of the waking experience. Whether a similar increase in wakefulness length leads to a comparable enhancement in NREM sleep cortical synchronization in young and older subjects is still a matter of debate in the literature. Here we evaluated the impact of 25-hours of wakefulness on SW during a daytime recovery sleep episode in 29 young (27y ±5), and 34 middle-aged (51y ±5) subjects. We also assessed whether age-related changes in NREM sleep cortical synchronization predicts the ability to maintain sleep during daytime recovery sleep. Compared to baseline sleep, sleep efficiency was lower during daytime recovery sleep in both age-groups but the effect was more prominent in the middle-aged than in the young subjects. In both age groups, SW density, amplitude, and slope increased whereas SW positive and negative phase duration decreased during daytime recovery sleep compared to baseline sleep, particularly in anterior brain areas. Importantly, compared to young subjects, middle-aged participants showed lower SW density rebound and SW positive phase duration enhancement after sleep deprivation during daytime recovery sleep. Furthermore, middle-aged subjects showed lower SW amplitude and slope enhancements after sleep deprivation than young subjects in frontal and prefrontal derivations only. None of the SW characteristics at baseline were associated with daytime recovery sleep efficiency. Our results support the notion that anterior brain areas elicit and may necessitate more intense recovery and that aging reduces enhancement of cortical synchronization after sleep loss, particularly in these areas. Age-related changes in the quality of wake experience may underlie age-related reduction in markers of cortical synchronization enhancement after sustained wakefulness. PMID

  1. Increased slow wave sleep and reduced stage 2 sleep in children depending on exercise intensity.

    Science.gov (United States)

    Dworak, Markus; Wiater, Alfred; Alfer, Dirk; Stephan, Egon; Hollmann, Wildor; Strüder, Heiko K

    2008-03-01

    There is controversy about the consequences of physical exercise on human sleeping behaviors. Evidence suggests that voluntary physical exercise affects brain structures and functions. However, there are inconsistent data regarding the effects of exercise on sleep architecture and sleep continuity, especially the amounts of slow wave sleep (SWS) and rapid eye movement (REM) sleep. The aim of the present study was to investigate the effects of moderate and high intense physical exercise on vigilance state and sleep patterns in school-aged children. Eleven healthy children (12.6+/-0.8 years old) were recruited for this polysomnographic study and underwent two exercise sessions. The two exercise sessions on a bicycle ergometer were performed 3-4h prior to bedtime, lasted 30min and varied in intensity. The moderate-intensity exercise was at 65-70% of maximal heart rate (HR(max)) while the high-intensity exercise was at 85-90% HR(max) to exhaustion. Polysomnographic and physiological measurements, including oximetry, were made on three nights in random order and separated by 1 week. Vigilance tests were carried out before and after the three sleep periods. Only high-intensity exercise resulted in a significantly elevated SWS proportion and less sleep in stage 2 as well as a higher sleep efficiency and shorter sleep onset latency. No significant effects on REM sleep were found. The results suggest that exercise intensity is responsible for the effects on stage 2 sleep and SWS in children and support the hypothesis of homeostatic sleep regulation.

  2. Daytime Ayahuasca administration modulates REM and slow-wave sleep in healthy volunteers.

    Science.gov (United States)

    Barbanoj, Manel J; Riba, Jordi; Clos, S; Giménez, S; Grasa, E; Romero, S

    2008-02-01

    Ayahuasca is a traditional South American psychoactive beverage and the central sacrament of Brazilian-based religious groups, with followers in Europe and the United States. The tea contains the psychedelic indole N,N-dimethyltryptamine (DMT) and beta-carboline alkaloids with monoamine oxidase-inhibiting properties that render DMT orally active. DMT interacts with serotonergic neurotransmission acting as a partial agonist at 5-HT(1A) and 5-HT(2A/2C) receptor sites. Given the role played by serotonin in the regulation of the sleep/wake cycle, we investigated the effects of daytime ayahuasca consumption in sleep parameters. Subjective sleep quality, polysomnography (PSG), and spectral analysis were assessed in a group of 22 healthy male volunteers after the administration of a placebo, an ayahuasca dose equivalent to 1 mg DMT kg(-1) body weight, and 20 mg d-amphetamine, a proaminergic drug, as a positive control. Results show that ayahuasca did not induce any subjectively perceived deterioration of sleep quality or PSG-measured disruptions of sleep initiation or maintenance, in contrast with d-amphetamine, which delayed sleep initiation, disrupted sleep maintenance, induced a predominance of 'light' vs 'deep' sleep and significantly impaired subjective sleep quality. PSG analysis also showed that similarly to d-amphetamine, ayahuasca inhibits rapid eye movement (REM) sleep, decreasing its duration, both in absolute values and as a percentage of total sleep time, and shows a trend increase in its onset latency. Spectral analysis showed that d-amphetamine and ayahuasca increased power in the high frequency range, mainly during stage 2. Remarkably, whereas slow-wave sleep (SWS) power in the first night cycle, an indicator of sleep pressure, was decreased by d-amphetamine, ayahuasca enhanced power in this frequency band. Results show that daytime serotonergic psychedelic drug administration leads to measurable changes in PSG and sleep power spectrum and suggest an

  3. Reduced slow-wave rebound during daytime recovery sleep in middle-aged subjects.

    Directory of Open Access Journals (Sweden)

    Marjolaine Lafortune

    Full Text Available Cortical synchronization during NREM sleep, characterized by electroencephalographic slow waves (SW 75 µV, is strongly related to the number of hours of wakefulness prior to sleep and to the quality of the waking experience. Whether a similar increase in wakefulness length leads to a comparable enhancement in NREM sleep cortical synchronization in young and older subjects is still a matter of debate in the literature. Here we evaluated the impact of 25-hours of wakefulness on SW during a daytime recovery sleep episode in 29 young (27 y ± 5, and 34 middle-aged (51 y ± 5 subjects. We also assessed whether age-related changes in NREM sleep cortical synchronization predicts the ability to maintain sleep during daytime recovery sleep. Compared to baseline sleep, sleep efficiency was lower during daytime recovery sleep in both age-groups but the effect was more prominent in the middle-aged than in the young subjects. In both age groups, SW density, amplitude, and slope increased whereas SW positive and negative phase duration decreased during daytime recovery sleep compared to baseline sleep, particularly in anterior brain areas. Importantly, compared to young subjects, middle-aged participants showed lower SW density rebound and SW positive phase duration enhancement after sleep deprivation during daytime recovery sleep. Furthermore, middle-aged subjects showed lower SW amplitude and slope enhancements after sleep deprivation than young subjects in frontal and prefrontal derivations only. None of the SW characteristics at baseline were associated with daytime recovery sleep efficiency. Our results support the notion that anterior brain areas elicit and may necessitate more intense recovery and that aging reduces enhancement of cortical synchronization after sleep loss, particularly in these areas. Age-related changes in the quality of wake experience may underlie age-related reduction in markers of cortical synchronization enhancement after

  4. Slow wave sleep enhancement with gaboxadol reduces daytime sleepiness during sleep restriction.

    Science.gov (United States)

    Walsh, James K; Snyder, Ellen; Hall, Janine; Randazzo, Angela C; Griffin, Kara; Groeger, John; Eisenstein, Rhody; Feren, Stephen D; Dickey, Pam; Schweitzer, Paula K

    2008-05-01

    To evaluate the impact of enhanced slow wave sleep (SWS) on behavioral, psychological, and physiological changes resulting from sleep restriction. A double-blind, parallel group, placebo-controlled design was used to compare gaboxadol (GBX) 15 mg, a SWS-enhancing drug, to placebo during 4 nights of sleep restriction (5 h/night). Behavioral, psychological, and physiological measures of the impact of sleep restriction were assessed in both groups at baseline, during sleep restriction and following recovery sleep. Sleep research laboratory. Forty-one healthy adults; 9 males and 12 females (mean age: 32.0 +/- 9.9 y) in the placebo group and 10 males and 10 females (mean age: 31.9 +/- 10.2 y) in the GBX group. Both experimental groups underwent 4 nights of sleep restriction. Each group received either GBX 15 mg or placebo on all sleep restriction nights, and both groups received placebo on baseline and recovery nights. Polysomnography documented a SWS-enhancing effect of GBX with no group difference in total sleep time during sleep restriction. The placebo group displayed the predicted deficits due to sleep restriction on the multiple sleep latency test (MSLT) and on introspective measures of sleepiness and fatigue. Compared to placebo, the GBX group showed significantly less physiological sleepiness on the MSLT and lower levels of introspective sleepiness and fatigue during sleep restriction. There were no differences between groups on the psychomotor vigilance task (PVT) and a cognitive test battery, but these measures were minimally affected by sleep restriction in this study. The correlation between change from baseline in MSLT on Day 6 and change from baseline in SWS on Night 6 was significant in the GBX group and in both group combined. The results of this study are consistent with the hypothesis that enhanced SWS, in this study produced by GBX, reduces physiological sleep tendency and introspective sleepiness and fatigue which typically result from sleep

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

    Science.gov (United States)

    Casey, Sarah J; Solomons, Luke C; Steier, Joerg; Kabra, Neeraj; Burnside, Anna; Pengo, Martino F; Moxham, John; Goldstein, Laura H; Kopelman, Michael D

    2016-11-01

    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. Participants completed a set of explicit and implicit memory tasks at night, prior to sleep. They had 1 control night of undisturbed sleep and 2 experimental nights, during which either SWS or REM sleep was selectively deprived across the entire night (sleep conditions counterbalanced across participants). Polysomnography recordings quantified precisely the amount of SWS and REM sleep that occurred during each of the sleep conditions, and spindle counts were recorded. In the morning, participants completed the experimental tasks in the same sequence as the night before. SWS deprivation disrupted the consolidation of explicit memories for visuospatial information (ηp2 = .23), and both SWS (ηp2 = .53) and REM sleep (ηp2 = .52) deprivation adversely affected explicit verbal recall. Neither SWS nor REM sleep deprivation affected aspects of short-term or working memory, and did not affect measures of verbal implicit memory. Spindle counts did not correlate significantly with memory performance. These findings demonstrate the importance of measuring the sleep cycles throughout the entire night, and the contribution of both SWS and REM sleep to memory consolidation. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  6. Coordination of Slow Waves With Sleep Spindles Predicts Sleep-Dependent Memory Consolidation in Schizophrenia.

    Science.gov (United States)

    Demanuele, Charmaine; Bartsch, Ullrich; Baran, Bengi; Khan, Sheraz; Vangel, Mark G; Cox, Roy; Hämäläinen, Matti; Jones, Matthew W; Stickgold, Robert; Manoach, Dara S

    2017-01-01

    Schizophrenia patients have correlated deficits in sleep spindle density and sleep-dependent memory consolidation. In addition to spindle density, memory consolidation is thought to rely on the precise temporal coordination of spindles with slow waves (SWs). We investigated whether this coordination is intact in schizophrenia and its relation to motor procedural memory consolidation. Twenty-one chronic medicated schizophrenia patients and 17 demographically matched healthy controls underwent two nights of polysomnography, with training on the finger tapping motor sequence task (MST) on the second night and testing the following morning. We detected SWs (0.5-4 Hz) and spindles during non-rapid eye movement (NREM) sleep. We measured SW-spindle phase-amplitude coupling and its relation with overnight improvement in MST performance. Patients did not differ from controls in the timing of SW-spindle coupling. In both the groups, spindles peaked during the SW upstate. For patients alone, the later in the SW upstate that spindles peaked and the more reliable this phase relationship, the greater the overnight MST improvement. Regression models that included both spindle density and SW-spindle coordination predicted overnight improvement significantly better than either parameter alone, suggesting that both contribute to memory consolidation. Schizophrenia patients show intact spindle-SW temporal coordination, and these timing relationships, together with spindle density, predict sleep-dependent memory consolidation. These relations were seen only in patients suggesting that their memory is more dependent on optimal spindle-SW timing, possibly due to reduced spindle density. Interventions to improve memory may need to increase spindle density while preserving or enhancing the coordination of NREM oscillations.

  7. 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.

  8. Application of oil-water discrimination technology in fractured reservoirs using the differences between fast and slow shear-waves

    Science.gov (United States)

    Luo, Cong; Li, Xiangyang; Huang, Guangtan

    2017-08-01

    Oil-water discrimination is of great significance in the design and adjustment of development projects in oil fields. For fractured reservoirs, based on anisotropic S-wave splitting information, it becomes possible to effectively solve such problems which are difficult to deal with in traditional longitudinal wave exploration, due to the similar bulk modulus and density of these two fluids. In this paper, by analyzing the anisotropic character of the Chapman model (2009 Geophysics 74 97-103), the velocity and reflection coefficient differences between the fast and slow S-wave caused by fluid substitution have been verified. Then, through a wave field response analysis of the theoretical model, we found that water saturation causes a longer time delay, a larger time delay gradient and a lower amplitude difference between the fast and slow S-wave, while the oil case corresponds to a lower time delay, a lower gradient and a higher amplitude difference. Therefore, a new class attribute has been proposed regarding the amplitude energy of the fast and slow shear wave, used for oil-water distinction. This new attribute, as well as that of the time delay gradient, were both applied to the 3D3C seismic data of carbonate fractured reservoirs in the Luojia area of the Shengli oil field in China. The results show that the predictions of the energy attributes are more consistent with the well information than the time delay gradient attribute, hence demonstrating the great advantages and potential of this new attribute in oil-water recognition.

  9. 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.

  10. 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.

  11. Observation of Quantum Shock Waves Created with Ultra- Compressed Slow Light Pulses in a Bose-Einstein Condensate

    Science.gov (United States)

    Dutton, Zachary; Budde, Michael; Slowe, Christopher; Vestergaard Hau, Lene

    2001-07-01

    We have used an extension of our slow light technique to provide a method for inducing small density defects in a Bose-Einstein condensate. These sub- resolution, micrometer-sized defects evolve into large-amplitude sound waves. We present an experimental observation and theoretical investigation of the resulting breakdown of superfluidity, and we observe directly the decay of the narrow density defects into solitons, the onset of the ``snake'' instability, and the subsequent nucleation of vortices.

  12. Observation of Quantum Shock Waves Created with Ultra Compressed Slow Light Pulses in a Bose-Einstein Condensate

    OpenAIRE

    Dutton, Zachary; Budde, Michael; Slowe, Christopher; Hau, Lene Vestergaard

    2001-01-01

    We have used an extension of our slow light technique to provide a method for inducing small density defects in a Bose-Einstein condensate. These sub-resolution, micron-sized defects evolve into large amplitude sound waves. We present an experimental observation and theoretical investigation of the resulting breakdown of superfluidity. We observe directly the decay of the narrow density defects into solitons, the onset of the `snake' instability, and the subsequent nucleation of vortices.

  13. Centrally located GLP-1 receptors modulate gastric slow waves and cardiovascular function in ferrets consistent with the induction of nausea.

    Science.gov (United States)

    Lu, Zengbing; Yeung, Chi-Kong; Lin, Ge; Yew, David T W; Andrews, P L R; Rudd, John A

    2017-10-01

    Glucagon-like peptide-1 (GLP-1) receptor agonists are indicated for the treatment of Type 2 diabetes and obesity, but can cause nausea and emesis in some patients. GLP-1 receptors are distributed widely in the brain, where they contribute to mechanisms of emesis, reduced appetite and aversion, but it is not known if these centrally located receptors also contribute to a modulation of gastric slow wave activity, which is linked causally to nausea. Our aim was to investigate the potential of the GLP-1 receptor agonist, exendin-4, administered into the 3rd ventricle to modulate emesis, feeding and gastric slow wave activity. Thermoregulation and cardiovascular parameters were also monitored, as they are disturbed during nausea. Ferrets were used as common laboratory rodents do not have an emetic reflex. A guide cannula was implanted into the 3rd ventricle for delivering a previously established dose of exendin-4 (10nmol), which had been shown to induce emesis and behaviours indicative of 'nausea'. Radiotelemetry recorded gastric myoelectric activity (GMA; slow waves), blood pressure and heart rate variability (HRV), and core temperature; food intake and behaviour were also assessed. Exendin-4 (10nmol, i.c.v.) decreased the dominant frequency of GMA, with an associated increase in the percentage of bradygastric power (lasting ~4h). Food intake was inhibited in all animals, with 63% exhibiting emesis. Exendin-4 also increased blood pressure (lasting ~24h) and heart rate (lasting ~7h), decreased HRV (lasting ~24h), and caused transient hyperthermia. None of the above parameters were emesis-dependent. The present study shows for the first time that gastric slow waves may be modulated by GLP-1 receptors in the brain through mechanisms that appear independent from emesis. Taken together with a reduction in HRV, the findings are consistent with changes associated with the occurrence of nausea in humans. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Involvement of spindles in memory consolidation is slow wave sleep-specific

    NARCIS (Netherlands)

    Cox, R.; Hofman, W.F.; Talamini, L.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

  15. 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…

  16. Slow wave sleep in the chronically fatigued: Power spectra distribution patterns in chronic fatigue syndrome and primary insomnia.

    Science.gov (United States)

    Neu, Daniel; Mairesse, Olivier; Verbanck, Paul; Le Bon, Olivier

    2015-10-01

    To investigate slow wave sleep (SWS) spectral power proportions in distinct clinical conditions sharing non-restorative sleep and fatigue complaints without excessive daytime sleepiness (EDS), namely the chronic fatigue syndrome (CFS) and primary insomnia (PI). Impaired sleep homeostasis has been suspected in both CFS and PI. We compared perceived sleep quality, fatigue and sleepiness symptom-intensities, polysomnography (PSG) and SWS spectral power distributions of drug-free CFS and PI patients without comorbid sleep or mental disorders, with a good sleeper control group. Higher fatigue without EDS and impaired perceived sleep quality were confirmed in both patient groups. PSG mainly differed in sleep fragmentation and SWS durations. Spectral analysis revealed a similar decrease in central ultra slow power (0.3-0.79Hz) proportion during SWS for both CFS and PI and an increase in frontal power proportions of faster frequencies during SWS in PI only. The latter was correlated to affective symptoms whereas lower central ultra slow power proportions were related to fatigue severity and sleep quality impairment. In combination with normal (PI) or even increased SWS durations (CFS), we found consistent evidence for lower proportions of slow oscillations during SWS in PI and CFS. Observing normal or increased SWS durations but lower proportions of ultra slow power, our findings suggest a possible quantitative compensation of altered homeostatic regulation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  17. Effect of Slow Wave Sleep Disruption on Metabolic Parameters in Adolescents.

    Science.gov (United States)

    Shaw, Natalie D; McHill, Andrew W; Schiavon, Michele; Kangarloo, Tairmae; Mankowski, Piotr W; Cobelli, Claudio; Klerman, Elizabeth B; Hall, Janet E

    2016-08-01

    Cross-sectional studies report a correlation between slow wave sleep (SWS) duration and insulin sensitivity (SI) in children and adults. Suppression of SWS causes insulin resistance in adults but effects in children are unknown. This study was designed to determine the effect of SWS fragmentation on SI in children. Fourteen pubertal children (11.3-14.1 y, body mass index 29(th) to 97(th) percentile) were randomized to sleep studies and mixed meal (MM) tolerance tests with and without SWS disruption. Beta-cell responsiveness (Φ) and SI were determined using oral minimal modeling. During the disruption night, auditory stimuli (68.1 ± 10.7/night; mean ± standard error) decreased SWS by 40.0 ± 8.0%. SWS fragmentation did not affect fasting glucose (non-disrupted 76.9 ± 2.3 versus disrupted 80.6 ± 2.1 mg/dL), insulin (9.2 ± 1.6 versus 10.4 ± 2.0 μIU/mL), or C-peptide (1.9 ± 0.2 versus 1.9 ± 0.1 ng/mL) levels and did not impair SI (12.9 ± 2.3 versus 10.1 ± 1.6 10(-4) dL/kg/min per μIU/mL) or Φ (73.4 ± 7.8 versus 74.4 ± 8.4 10(-9) min(-1)) to a MM challenge. Only the subjects in the most insulin-sensitive tertile demonstrated a consistent decrease in SI after SWS disruption. Pubertal children across a range of body mass indices may be resistant to the adverse metabolic effects of acute SWS disruption. Only those subjects with high SI (i.e., having the greatest "metabolic reserve") demonstrated a consistent decrease in SI. These results suggest that adolescents may have a unique ability to adapt to metabolic stressors, such as acute SWS disruption, to maintain euglycemia. Additional studies are necessary to confirm that this resiliency is maintained in settings of chronic SWS disruption. © 2016 Associated Professional Sleep Societies, LLC.

  18. 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.

  19. Epileptic encephalopathy with continuous spikes and waves in the occipito-temporal region during slow-wave sleep in two patients with acquired Kanji dysgraphia.

    Science.gov (United States)

    Kuki, Ichiro; Kawawaki, Hisashi; Okazaki, Shin; Ikeda, Hiroko; Tomiwa, Kiyotaka

    2014-12-01

    We encountered two patients with acquired Kanji dysgraphia in whom continuous spikes and waves, dominant in the occipito-temporal region, were recorded during slow-wave sleep. Electrical status epileptics during sleep (ESES) was demonstrated on overnight electroencephalography, and dipoles clustered in and around the posterior inferior temporal cortex on magnetoencephalography. Functional neuroimaging suggested dysfunction in the left posterior temporal lobe, including the posterior inferior temporal cortex. The patients had normal intelligence with no problems in reading and writing Kana, as well as copying, reading aloud, and identifying Kanjis, but showed Kanji dysgraphia (morphological, phonemic, and semantic error) accompanied by impaired visual processing. ESES was resolved by sodium valproate, clonazepam, and acetazolamide in Patient 1, and by adrenocorticotropic hormone, sodium valproate, and clorazepate in Patient 2. The present cases had the unique cognitive dysfunction of Kanji dysgraphia, which is distinct from that of Landau-Kleffner syndrome and continuous spikes and waves during slow-wave sleep. However, the present cases also share common features with these two encephalopathies in terms of the clinical course, pathophysiology, neuroimaging, and response to steroids and antiepileptic drugs. In the context of the Japanese language, acquired Kanji dysgraphia may occur due to electrical dysfunction of left posterior inferior temporal cortex in patients with ESES.

  20. Multichannel filtering and reconstruction of ultrasonic guided wave fields using time intercept-slowness transform.

    Science.gov (United States)

    Tran, Tho N H T; Le, Lawrence H; Sacchi, Mauricio D; Nguyen, Vu-Hieu; Lou, Edmond H M

    2014-07-01

    Multichannel ultrasonic axial-transmission data are multimodal by nature. As guided waves are commonly used in nondestructive material testing, wave field filtering becomes important because the analysis is usually limited to a few lower-order modes and requires their extraction. An application of the Radon transform to enhance signal-to-noise ratio and separate wave fields in ultrasonic records is presented. The method considers guided wave fields as superpositions of plane waves defined by ray parameters (p) and time intercepts (τ) and stacks the amplitudes along linear trajectories, mapping time-offset (t - x) data to a τ - p or Radon panel. The transform is implemented using a least-squares strategy with Cauchy-norm regularization that serves to enhance the focusing power. The method was verified using simulated data and applied to an uneven spatially sampled bovine-bone-plate data set. The results demonstrate the Radon panels show isolated amplitude clusters and the Cauchy-norm constraint provides a more focused Radon image than the damped least-squares regularization. Wave field separation can be achieved by selectively windowing the τ - p signals and inverse transformation, which is illustrated by the successful extraction of the A0 mode in bone plate. In addition, the method effectively attenuates noise, enhances the coherency of the guided wave modes, and reconstructs the missing records. The proposed transform presents a powerful signal-enhancement tool to process guided waves for further analysis and inversion.

  1. Local Increase of Sleep Slow Wave Activity after Three Weeks of Working Memory Training in Children and Adolescents

    Science.gov (United States)

    Pugin, Fiona; Metz, Andreas J.; Wolf, Martin; Achermann, Peter; Jenni, Oskar G.; Huber, Reto

    2015-01-01

    Study Objectives: Evidence is accumulating that electroencephalographic (EEG) sleep slow wave activity (SWA), the key characteristic of deep sleep, is regulated not only globally, but also locally. Several studies have shown local learning- and use-dependent changes in SWA. In vitro and in vivo animal experiments and studies in humans indicate that these local changes in SWA reflect synaptic plasticity. During maturation, when synaptic changes are most prominent, learning is of utmost importance. Thus, in this study, we aimed to examine whether intensive working memory training for 3 w would lead to a local increase of sleep SWA using high-density EEG recordings in children and young adolescents. Setting: Sleep laboratory at the University Children's Hospital Zurich. Participants: Fourteen healthy subjects between 10 and 16 y. Interventions: Three weeks of intensive working memory training. Measurements and Results: After intensive working memory training, sleep SWA was increased in a small left frontoparietal cluster (11.06 ± 1.24%, mean ± standard error of the mean). In addition, the local increase correlated positively with increased working memory performance assessed immediately (r = 0.66) and 2 to 5 mo (r = 0.68) after the training. Conclusions: The increase in slow wave activity (SWA) correlates with cognitive training-induced plasticity in a region known to be involved in working memory performance. Thus, in future, the mapping of sleep SWA may be used to longitudinally monitor the effects of working memory training in children and adolescents with working memory deficiencies. Citation: Pugin F, Metz AJ, Wolf M, Achermann P, Jenni OG, Huber R. Local increase of sleep slow wave activity after three weeks of working memory training in children and adolescents. SLEEP 2015;38(4):607–614. PMID:25669190

  2. Wavelet analysis of the slow non-linear dynamics of wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Miquel, Benjamin; Mordant, Nicolas, E-mail: benjamin.miquel@lps.ens.fr [Laboratoire de Physique Statistique, Ecole Normale Superieure (France)

    2011-12-22

    In wave turbulence, the derivation of solutions in the frame of the Weak Turbulence Theory relies on the existence of a double time-scale separation: first, between the period of the waves and characteristic nonlinear time t{sub NL} corresponding to energy exchange among waves; and secondly, between t{sub NL} and the characteristic dissipation time t{sub d}. Due to the lack of space and time resolved measurement, this hypothesis have remained unverified so far. We study the turbulence of flexion waves in thin elastic plates. t{sub d} is measured using the decline stage of the turbulence whereas a wavelet analysis is performed to measure the characteristic non-linear time t{sub NL}.

  3. Heightened Delta Power during Slow-Wave-Sleep in Patients with Rett Syndrome Associated with Poor Sleep Efficiency.

    Science.gov (United States)

    Ammanuel, Simon; Chan, Wesley C; Adler, Daniel A; Lakshamanan, Balaji M; Gupta, Siddharth S; Ewen, Joshua B; Johnston, Michael V; Marcus, Carole L; Naidu, Sakkubai; Kadam, Shilpa D

    2015-01-01

    Sleep problems are commonly reported in Rett syndrome (RTT); however the electroencephalographic (EEG) biomarkers underlying sleep dysfunction are poorly understood. The aim of this study was to analyze the temporal evolution of quantitative EEG (qEEG) biomarkers in overnight EEGs recorded from girls (2-9 yrs. old) diagnosed with RTT using a non-traditional automated protocol. In this study, EEG spectral analysis identified high delta power cycles representing slow wave sleep (SWS) in 8-9h overnight sleep EEGs from the frontal, central and occipital leads (AP axis), comparing age-matched girls with and without RTT. Automated algorithms quantitated the area under the curve (AUC) within identified SWS cycles for each spectral frequency wave form. Both age-matched RTT and control EEGs showed similar increasing trends for recorded delta wave power in the EEG leads along the antero-posterior (AP). RTT EEGs had significantly fewer numbers of SWS sleep cycles; therefore, the overall time spent in SWS was also significantly lower in RTT. In contrast, the AUC for delta power within each SWS cycle was significantly heightened in RTT and remained heightened over consecutive cycles unlike control EEGs that showed an overnight decrement of delta power in consecutive cycles. Gamma wave power associated with these SWS cycles was similar to controls. However, the negative correlation of gamma power with age (r = -.59; pcycles. Therefore, qEEG biomarkers of SWS in RTT evolved temporally and correlated significantly with clinical severity.

  4. Shear-wave velocity structure of the Tongariro Volcanic Centre, New Zealand: Fast Rayleigh and slow Love waves indicate strong shallow anisotropy

    Science.gov (United States)

    Godfrey, Holly J.; Fry, Bill; Savage, Martha K.

    2017-04-01

    Models of the velocity structure of volcanoes can help define possible magma pathways and contribute to calculating more accurate earthquake locations, which can help with monitoring volcanic activity. However, shear-wave velocity of volcanoes is difficult to determine from traditional seismic techniques, such as local earthquake tomography (LET) or refraction/reflection surveys. Here we use the recently developed technique of noise cross correlation of continuous seismic data to investigate the subsurface shear-wave velocity structure of the Tongariro Volcanic Centre (TgVC) of New Zealand, focusing on the active Ruapehu and Tongariro Volcanoes. We observe both the fundamental and first higher-order modes of Rayleigh and Love waves within our noise dataset, made from stacks of 15 min cross-correlation functions. We manually pick group velocity dispersion curves from over 1900 correlation functions, of which we consider 1373 to be high quality. We subsequently invert a subset of the fundamental mode Rayleigh- and Love-wave dispersion curves both independently and jointly for one dimensional shear-wave velocity (Vs) profiles at Ruapehu and Tongariro Volcanoes. Vs increases very slowly at a rate of approximately 0.2 km/s per km depth beneath Ruapehu, suggesting that progressive hydrothermal alteration mitigates the effects of compaction driven velocity increases. At Tongariro, we observe larger Vs increases with depth, which we interpret as different layers within Tongariro's volcanic system above altered basement greywacke. Slow Vs, on the order of 1-2 km/s, are compatible with P-wave velocities (using a Vp/Vs ratio of 1.7) from existing velocity profiles of areas within the TgVC, and the observations of worldwide studies of shallow volcanic systems that used ambient noise cross-correlation methods. Most of the measured group velocities of fundamental mode Love-waves across the TgVC are 0.1-0.4 km/s slower than those of fundamental mode Rayleigh-waves in the

  5. Local increase of sleep slow wave activity after three weeks of working memory training in children and adolescents.

    Science.gov (United States)

    Pugin, Fiona; Metz, Andreas J; Wolf, Martin; Achermann, Peter; Jenni, Oskar G; Huber, Reto

    2015-04-01

    Evidence is accumulating that electroencephalographic (EEG) sleep slow wave activity (SWA), the key characteristic of deep sleep, is regulated not only globally, but also locally. Several studies have shown local learning- and use-dependent changes in SWA. In vitro and in vivo animal experiments and studies in humans indicate that these local changes in SWA reflect synaptic plasticity. During maturation, when synaptic changes are most prominent, learning is of utmost importance. Thus, in this study, we aimed to examine whether intensive working memory training for 3 w would lead to a local increase of sleep SWA using high-density EEG recordings in children and young adolescents. Sleep laboratory at the University Children's Hospital Zurich. Fourteen healthy subjects between 10 and 16 y. Three weeks of intensive working memory training. After intensive working memory training, sleep SWA was increased in a small left frontoparietal cluster (11.06 ± 1.24%, mean ± standard error of the mean). In addition, the local increase correlated positively with increased working memory performance assessed immediately (r = 0.66) and 2 to 5 mo (r = 0.68) after the training. The increase in slow wave activity (SWA) correlates with cognitive training-induced plasticity in a region known to be involved in working memory performance. Thus, in future, the mapping of sleep SWA may be used to longitudinally monitor the effects of working memory training in children and adolescents with working memory deficiencies. © 2015 Associated Professional Sleep Societies, LLC.

  6. Roles of convective heating and boundary-layer moisture asymmetry in slowing down the convectively coupled Kelvin waves

    Science.gov (United States)

    Wang, Lu; Li, Tim

    2017-04-01

    Mechanisms for an in-phase relationship between convection and low-level zonal wind and the slow propagation of the convectively coupled Kelvin wave (CCKW) are investigated by analyzing satellite-based brightness temperature and reanalysis data and by constructing a simple theoretical model. Observational data analysis reveals an eastward shift of the low-level convergence and moisture relative to the CCKW convective center. The composite vertical structures show that the low-level convergence lies in the planetary boundary layer (PBL) (below 800 hPa), and is induced by the pressure trough above the top of PBL through an Ekman-pumping process. A traditional view of a slower eastward propagation speed compared to the dry Kelvin waves is attributed to the reduction of atmospheric static stability in mid-troposphere due to the convective heating effect. The authors' quantitative assessment of the heating effect shows that this effect alone cannot explain the observed CCKW phase speed. We hypothesize that additional slowing process arises from the effect of zonally asymmetric PBL moisture. A simple theoretical model is constructed to understand the relative role of the heating induced effective static stability effect and the PBL moisture effect. The result demonstrates the important role of the both effects. Thus, PBL-free atmosphere interaction is important in explaining the observed structure and propagation of CCKW.

  7. Cross-hemispheric Alternating Current Stimulation During a Nap Disrupts Slow Wave Activity and Associated Memory Consolidation.

    Science.gov (United States)

    Garside, Peter; Arizpe, Joseph; Lau, Chi-Ieong; Goh, Crystal; Walsh, Vincent

    2015-01-01

    Slow Wave Activity (SWA), the low frequency (memory consolidation during nocturnal sleep. Evidence is conflicting relating SWA to memory consolidation during nap however. We applied transcranial alternating current stimulation (tACS) - which, with a cross-hemispheric electrode montage (F3 and F4 - International 10:20 EEG system), is able to disrupt brain oscillations-to determine if disruption of low frequency oscillation generation during afternoon nap is causally related to disruption in declarative memory consolidation. Eight human subjects each participated in stimulation and sham nap sessions. A verbal paired associate learning (PAL) task measured memory changes. During each nap period, five 5-min stimulation (0.75 Hz cross-hemispheric frontal tACS) or sham intervals were applied with 1-min post-stimulation intervals (PSI's). Spectral EEG power for Slow (0.7-0.8 Hz), Delta (1.0-4.0 Hz), Theta (4.0-8.0 Hz), Alpha (8.0-12.0 Hz), and Spindle-range (12.0-14.0) frequencies was analyzed during the 1-min preceding the onset of stimulation and the 1-min PSI's. As hypothesized, power reduction due to stimulation positively correlated with reduction in word-pair recall post-nap specifically for Slow (P memory consolidation during nap. Published by Elsevier Inc.

  8. Differences in EEG delta frequency characteristics and patterns in slow-wave sleep between dementia patients and controls: a pilot study.

    Science.gov (United States)

    Bonanni, Enrica; Di Coscio, Elisa; Maestri, Michelangelo; Carnicelli, Luca; Tsekou, Hara; Economou, Nicholas Tiberio; Paparrigopoulos, Thomas; Bonakis, Anastasios; Papageorgiou, Sokratis G; Vassilopoulos, Dimitris; Soldatos, Constantin R; Murri, Luigi; Ktonas, Periklis Y

    2012-02-01

    To evaluate the modifications of EEG activity during slow-wave sleep in patients with dementia compared with healthy elderly subjects, using spectral analysis and period-amplitude analysis. Five patients with dementia and 5 elderly control subjects underwent night polysomnographic recordings. For each of the first three nonrapid eye movement-rapid eye movement sleep cycles, a well-defined slow-wave sleep portion was chosen. The delta frequency band (0.4-3.6 Hz) in these portions was analyzed with both spectral analysis and period-amplitude analysis. Spectral analysis showed an increase in the delta band power in the dementia group, with a decrease across the night observed only in the control group. For the dementia group, period-amplitude analysis showed a decrease in well-defined delta waves of frequency lower than 1.6 Hz and an increase in such waves of frequency higher than 2 Hz, in incidence and amplitude. Our study showed (1) a loss of the dynamics of delta band power across the night sleep, in dementia, and (2) a different distribution of delta waves during slow-wave sleep in dementia compared with control subjects. This kind of computer-based analysis can highlight the presence of a pathologic delta activity during slow-wave sleep in dementia and may support the hypothesis of a dynamic interaction between sleep alteration and cognitive decline.

  9. 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.

  10. When function mirrors structure: how slow waves are shaped by cortical layers

    Directory of Open Access Journals (Sweden)

    Cristiano Capone

    2015-04-01

    As the model predicted, we found that strips of early wave propagation reliably overlapped with the regions where maximum Up state duration and firing activity occurred, strengthening the duality between spontaneous activity and network structure. Finally, we matched the excitable strips with the slice cortical layers as identified by histology, finding a reliable overlap between such strips and L4 and L5 (see Figure 1E. Figure 1. A. Wavefronts for 2 modes of propagation. B. Average strips where wavefronts propagate earlier (black, and where Up states have maximum duration (green and magnitude (blue. C. Modulation of the connectivity parameter in the model. D. Nullclines under mean-field approximation varying levels of connectivity.  and C are average firing rate and fatigue level, respectively. Circles, fixed points. Dark to light gray, different excitability levels as in C, respectively. E. Example match between strip of early wave propagation and slice’s layers.

  11. Noise and slow-fast dynamics in a three-wave resonance problem

    CERN Document Server

    Lythe, G D

    1997-01-01

    Recent research on the dynamics of certain fluid dynamical instabilities shows that when there is a slow invariant manifold subject to fast timescale instability the dynamics are extremely sensitive to noise. The behaviour of such systems can be described in terms of a one-dimensional map, and previous work has shown how the effect of noise can be modelled by a simple adjustment to the map. Here we undertake an in depth investigation of a particular set of equations, using the methods of stochastic integration. We confirm the prediction of the earlier studies that the noise becomes important when mu|log(epsilon)| = O(1), where mu is the small timescale ratio and \\epsilon is the noise level. In addition, we present detailed information about the statistics of the solution when the noise is a dominant effect; the analytical results show excellent agreement with numerical simulations.

  12. Mortality salience modulates cortical responses to painful somatosensory stimulation: Evidence from slow wave and delta band activity.

    Science.gov (United States)

    Valentini, Elia; Koch, Katharina; Nicolardi, Valentina; Aglioti, Salvatore Maria

    2015-10-15

    Social psychology studies show that awareness of one's eventual death profoundly influences human cognition and behaviour by inducing defensive reactions against end-of-life-related anxiety. Much less is known about the impact of reminders of mortality on brain activity. Here we tested whether reminders of mortality can induce a modulation of the slow electroencephalographic activity triggered by somatosensory nociceptive or auditory threatening stimulation and if this modulation is related to mood and anxiety as well as personality traits. We found a specific slow wave (SW) modulation only for nociceptive stimulation and only following mortality salience induction (compared to reminders of an important failed exam). The enhancement of SW negativity at the scalp vertex was associated with increased state anxiety and negative mood, whereas higher self-esteem was associated with reduced SW amplitude. In addition, mortality salience was linked to an increased amplitude of frontal delta band, which was correlated also with increased positive mood and higher self-esteem. The results indicate that SW and delta spectral activity may represent both proximal and distal defences associated with reminders of death and that neurophysiological correlates of somatosensory representation of painful and threatening stimuli may be useful for existential neuroscience studies. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. 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.

  14. Nonlinear waves in solids with slow dynamics: an internal-variable model

    Science.gov (United States)

    Berjamin, H.; Favrie, N.; Lombard, B.; Chiavassa, G.

    2017-05-01

    In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease, known as `slow dynamics', occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. (2004 Phys. Rev. E 70, 015602. (doi:10.1103/PhysRevE.70.015602)) is based on a variable that describes the softening of the material. However, this model is one dimensional and it is not thermodynamically admissible. In the present article, a three-dimensional model is derived in the framework of the finite-strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitutive law is deduced from the Clausius-Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of the continuum is thermodynamically admissible and dissipative (inelastic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments.

  15. Extracellular Cl-regulates electrical slow waves and setting of smooth muscle membrane potential by interstitial cells of Cajal in mouse jejunum.

    Science.gov (United States)

    Saravanaperumal, Siva Arumugam; Gibbons, Simon J; Malysz, John; Sha, Lei; Linden, David R; Szurszewski, Joseph H; Farrugia, Gianrico

    2018-01-01

    What is the central question of this study? The aim was to investigate the roles of extracellular chloride in electrical slow waves and resting membrane potential of mouse jejunal smooth muscle by replacing chloride with the impermeant anions gluconate and isethionate. What is the main finding and its importance? The main finding was that in smooth muscle cells, the resting Cl - conductance is low, whereas transmembrane Cl - movement in interstitial cells of Cajal (ICCs) is a major contributor to the shape of electrical slow waves. Furthermore, the data confirm that ICCs set the smooth muscle membrane potential and that altering Cl - homeostasis in ICCs can alter the smooth muscle membrane potential. Intracellular Cl - homeostasis is regulated by anion-permeable channels and transporters and contributes to excitability of many cell types, including smooth muscle and interstitial cells of Cajal (ICCs). Our aims were to investigate the effects on electrical activity in mouse jejunal muscle strips of replacing extracellular Cl - (Cl - o ) with the impermeant anions gluconate and isethionate. On reducing Cl - o , effects were observed on electrical slow waves, with small effects on smooth muscle membrane voltage (E m ). Restoration of Cl - hyperpolarized smooth muscle E m proportional to the change in Cl - o concentration. Replacement of 90% of Cl - o with gluconate reversibly abolished slow waves in five of nine preparations. Slow waves were maintained in isethionate. Gluconate and isethionate substitution had similar concentration-dependent effects on peak amplitude, frequency, width at half peak amplitude, rise time and decay time of residual slow waves. Gluconate reduced free ionized Ca 2+ in Krebs solutions to 0.13 mm. In Krebs solutions containing normal Cl - and 0.13 mm free Ca 2+ , slow wave frequency was lower, width at half peak amplitude was smaller, and decay time was faster. The transient hyperpolarization following restoration of Cl - o was not observed

  16. Surface Waves from the Hawaiian PLUME Project Trace Anomalously Slow Lithosphere and Asthenosphere

    Science.gov (United States)

    Laske, G.; Markee, A.; Orcutt, J. A.; Collins, J. A.; Wolfe, C. J.; Solomon, S. C.; Detrick, R. S.; Bercovici, D. A.; Hauri, E. H.

    2009-04-01

    During the two-stage Hawaiian PLUME (Plume-Lithosphere Undersea Melt Experiment) deployment, we collected continuous seismic data at ten land stations and nearly 70 ocean bottom sites from 2005 through mid-2007. In the first stage from January 2005 through January 2006, 35 sites were occupied in an elongated array centered on the island of Hawaii, with a station spacing of roughly 75 km and an aperture of 500 km. In the second stage from May 2006 through June 2007, 37 sites were occupied in a larger array with a station spacing of roughly 200 km. Most of the sites were occupied with broad-band seismometers. This allows for an analysis of surface waves in a broad frequency band. Our current analysis concentrates on long-period teleseismic Rayleigh waves. During the first stage, we collected records from upward of 95 suitable shallow earthquakes (source depth less than 200 km) with surface wave magnitudes of 5.6 or larger. We also identified and analyzed 70 smaller events. The initial data set of the second stage is quite a bit larger, and our initial analysis concentrates on 163 larger earthquakes. Our set of 5000 unique single-station phase measurements for the first stage and 3100 for the second form the basis to obtain two-station path-averaged phase velocity curves. Each curve is well constrained by many earthquakes (typically 10-20). The data are internally consistent between 15 and 80 s, allowing us to image the lithosphere and upper asthenosphere. Some larger events provide constraints beyond 100 s which allows us to reach deeper. Using these dispersion curves we invert for phase velocity maps at fixed frequency but also for path-averaged depth profiles, and ultimately for a full 3D model. For the two deployment stages, we currently have over 300 and 200 two-station paths respectively. Compared to 100-million year old upper mantle, our analysis reveals a roughly 30 km thick low-velocity anomaly in the lower lithosphere, surrounding the island of Hawaii, that

  17. Bowel Movement

    Science.gov (United States)

    ... passes through the large intestine too slowly. Bowel incontinence is a problem controlling your bowel movements. Other abnormalities with bowel movements may be a sign of a digestive problem. NIH: National Institute of Diabetes and Digestive and Kidney Diseases

  18. What drives slow wave activity during early non-REM sleep: Learning during prior wake or effort?

    Directory of Open Access Journals (Sweden)

    Ziyang Li

    Full Text Available What is the function of sleep in humans? One claim is that sleep consolidates learning. Slow wave activity (SWA, i.e. slow oscillations of frequency < 4 Hz, has been observed in electroencephalograms (EEG during sleep; it increases with prior wakefulness and decreases with sleep. Studies have claimed that increase in SWA in specific regions of the sleeping brain is correlated with overnight improved performance, i.e. overnight consolidation, on a demanding motor learning task. We wondered if SWA change during sleep is attributable to overnight consolidation or to metabolic demand. Participants executed out-and-back movements to a target using a pen-like cursor with their dominant hand while the target and cursor position were displayed on a screen. They trained on three different conditions on separate nights, differing in the amount and degree of rotation between the actual hand movement direction and displayed cursor movement direction. In the no-rotation (NR condition, there was no rotation. In the single rotation (SR condition, the amount of rotation remained the same throughout, and performance improved both across pre-sleep training and after sleep, i.e. overnight consolidation occurred; in the random rotation (RR condition, the amount of rotation varied randomly from trial to trial, and no overnight consolidation occurred; SR and RR were cognitively demanding. The average EEG power density of SWA for the first 30 min. of non-rapid eye movement sleep after training was computed. Both SR and RR elicited increase in SWA in the parietal region; furthermore, the topographic distribution of SWA in each was remarkably similar. No correlation was found between the overnight performance improvement on SR and the SWA change in the parietal region on measures of learning. Our results argue that regulation of SWA in early sleep is associated with high levels of cognitive effort during prior wakefulness, and not just overnight consolidation.

  19. 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

  20. Quantitative Analysis of the Effects of Slow Wave Sleep Deprivation During the First 3 h of Sleep on Subsequent EEG Power Density

    NARCIS (Netherlands)

    Dijk, Derk Jan; Beersma, Domien G.M.; Daan, Serge; Bloem, Gerda M.; Hoofdakker, Rutger H. van den

    1987-01-01

    The relation between EEG power density during slow wave sleep (SWS) deprivation and power density during subsequent sleep was investigated. Nine young male adults slept in the laboratory for 3 consecutive nights. Spectral analysis of the EEG on the 2nd (baseline) night revealed an exponential

  1. Changes of sleep EEG slow-wave activity in response to sleep manipulations : to what extent are they related to changes in REM sleep latency?

    NARCIS (Netherlands)

    Beersma, D.G.M.; Achermann, P.

    1995-01-01

    Sleep interventions may have direct effects on slow-wave activity (SWA, i.e. power of the sleep EEG signal in the 0.75-4.5 Hz range) as well as indirect ones caused by changes in REM sleep (REMS) latency. The effects of changes in REMS latency on SWA were investigated by analysing simulations with a

  2. LONG TERM FOLLOW-UP OF LESIONAL AND NON-LESIONAL PATIENTS WITH ELECTRICAL STATUS EPILEPTICUS IN SLOW WAVE SLEEP.

    Science.gov (United States)

    Hegyi, Márta; Siegler, Zsuzsa; Fogarasi, András; Barsi, Péter; Halász, Péter

    2016-01-30

    A retrospective study has been done at the Bethesda Children's Hospital Epilepsy Center with those patients whose EEG records fulfilled in one or more records the criteria of electrical status epilepticus in slow wave sleep (ESES) pattern, occupying at least 75% of NREM sleep with bilateral discharges, and had detailed disease history and long term follow-up data, between 2000 and 2012. PATIENTS AND METHODS--Thirty-three patients (mean 11.1 +/- 4.2 years of age) were studied by 171 sleep EEG records. Sleep was recorded after sleep deprivation or during spontaneous sleep at least for one hour length of NREM. From the 492 EEGs, 171 sleep records were performed (average five/patient). Average follow-up time was 7.5 years. Eighty-two ESES records have been analyzed in 15 non-lesional and 18 lesional (11 with dysgenetic and seven with perinatal-asphyxic or vascular origin) patients. Variability of seizure types, seizure frequency and frequency of status epilepticus was higher in the lesional group. Impairment of the cognitive functions was moderate and partial in the non-lesional, while severely damaged in the lesional group. EEG records of 29 patients shawed unihemispherial spike fields with a perpendicular axis (in anterior, medial and posterior variants) to the Sylvian fissure, regardless their lesional or non-lesional origin. Only three (lone nonlesional and two lesional) patients had bilateral synchronous spike-wave discharges with bilateral symmetric frontocentral spike fields. The individual discharges of the sleep EEG pattern were very similar to the awake interictal records except their extension in time and field, their increased number, amplitude, and continuity of them and furthermore in the increased trans-hemispheral propagation and their synchronity. Assumed circuits involved in the pathomechanism of discharges during NREM sleep in ESES are discussed based on our findings.

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

    Science.gov (United States)

    Huang, Ming-Xiong; Nichols, Sharon; Baker, Dewleen G; Robb, Ashley; Angeles, Annemarie; Yurgil, Kate A; Drake, Angela; Levy, Michael; Song, Tao; McLay, Robert; Theilmann, Rebecca J; Diwakar, Mithun; Risbrough, Victoria B; Ji, Zhengwei; Huang, Charles W; Chang, Douglas G; Harrington, Deborah L; Muzzatti, Laura; Canive, Jose M; Christopher Edgar, J; Chen, Yu-Han; Lee, Roland R

    2014-01-01

    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.

  4. 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.

  5. Developmental trajectories of EEG sleep slow wave activity as a marker for motor skill development during adolescence: a pilot study.

    Science.gov (United States)

    Lustenberger, Caroline; Mouthon, Anne-Laure; Tesler, Noemi; Kurth, Salome; Ringli, Maya; Buchmann, Andreas; Jenni, Oskar G; Huber, Reto

    2017-01-01

    Reliable markers for brain maturation are important to identify neural deviations that eventually predict the development of mental illnesses. Recent studies have proposed topographical EEG-derived slow wave activity (SWA) during NREM sleep as a mirror of cortical development. However, studies about the longitudinal stability as well as the relationship with behavioral skills are needed before SWA topography may be considered such a reliable marker. We examined six subjects longitudinally (over 5.1 years) using high-density EEG and a visuomotor learning task. All subjects showed a steady increase of SWA at a frontal electrode and a decrease in central electrodes. Despite these large changes in EEG power, SWA topography was relatively stable within each subject during development indicating individual trait-like characteristics. Moreover, the SWA changes in the central cluster were related to the development of specific visuomotor skills. Taken together with the previous work in this domain, our results suggest that EEG sleep SWA represents a marker for motor skill development and further supports the idea that SWA mirrors cortical development during childhood and adolescence. © 2016 Wiley Periodicals, Inc.

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

    Directory of Open Access Journals (Sweden)

    Diego Robles Mazzotti

    2014-06-01

    Full Text Available 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, one-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.

  7. Relic gravitational waves in the frame of slow-roll inflation with a power-law potential and the detection

    CERN Document Server

    Tong, Ming-Lei

    2013-01-01

    We obtained the analytic solutions of relic gravitational waves (RGWs) for the slow-roll inflation with a power-law form potential of the scalar field, $V=\\lambda\\phi^n$. Based on a reasonable range of $n$ constrained by cosmic microwave background (CMB) observations, we give tight constraints of the tensor-to-scalar ratio $r$ and the inflation expansion index $\\beta$ for the fixed scalar spectral index $n_s$. Even though, the spectrum of RGWs in low frequencies is hardly depends on any parameters, the high frequency parts will be affected by several parameters, such as $n_s$, the reheating temperature $T_{RH}$ and the index $\\beta_s$ describing the expansion from the end of inflation to the reheating process. We analyzed in detail all the factors which would affect the spectrum of RGWs in high frequencies including the quantum normalization. We found that the future GW detectors SKA, LISA, BBO and DECIGO are promising to catch the signals of RGWs. Furthermore, BBO and DECIGO have the potential not only to di...

  8. Offline consolidation of memory varies with time in slow wave sleep and can be accelerated by cuing memory reactivations.

    Science.gov (United States)

    Diekelmann, Susanne; Biggel, Simon; Rasch, Björn; Born, Jan

    2012-09-01

    Memory representations are reactivated during slow-wave sleep (SWS) after learning, and these reactivations cause a beneficial effect of sleep for memory consolidation. Memory reactivations can also be externally triggered during sleep by associated cues which enhance the sleep-dependent memory consolidation process. Here, we compared in humans the influence of sleep periods (i) of 40min and (ii) of 90min without externally triggered reactivations and (iii) of externally triggered reactivations by an associated odor cue during a 40-min sleep period on the consolidation of previously learned hippocampus-dependent visuo-spatial memories. We show that external reactivation by an odor cue during the 40-min sleep period enhanced memory stability to the same extent as 90min of sleep without odor reactivation. In contrast, 40min of sleep without external reactivations were not sufficient to benefit memory. In the 90-min sleep condition, memory enhancements were associated with time spent in SWS and were independent of the presence or absence of REM sleep. These results suggest that the efficacy of hippocampus-dependent memory consolidation depends on the duration of sleep and particularly SWS. External reactivation cues can accelerate the consolidation process even during shorter sleep episodes. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Selective slow-wave sleep deprivation and time-of-night effects on cognitive performance upon awakening.

    Science.gov (United States)

    Ferrara, M; De Gennaro, L; Casagrande, M; Bertini, M

    2000-07-01

    We evaluated the effects of selective slow-wave sleep (SWS) deprivation and time-of-night factors on cognitive performance upon awakening. Ten normal men slept for 6 consecutive nights in the laboratory: 1 adaptation, 2 baseline, 2 selective SWS deprivation, and 1 recovery night. Cognitive performance was assessed by means of a Descending Subtraction Task after 2, 5, and 7.5 h of sleep. There was an almost complete selective SWS suppression during both deprivation nights, and a significant SWS rebound during the recovery sleep. Regarding cognitive performance, a progressive linear decrease of sleep inertia upon successive awakenings was found during all experimental nights except for the recovery night. In addition, a significant decrease of sleep inertia was observed upon the morning awakening of the second deprivation night for the measure of performance speed, and a significant increase of sleep inertia upon the morning awakening of the recovery night for the measure of performance accuracy. The results show that cognitive performance upon awakening is adversely affected by sleep depth and that, during the sleep-wake transition, cognitive performance accuracy is more impaired than performance speed.

  10. [A comparative study of three systems for quantifying the spike and wave index in patients with continuous spikes and waves during slow sleep].

    Science.gov (United States)

    Azcona, G; Gurtubay, I G; Mosquera, A; Ibanez, B; Cambra, K; Aguilera-Albesa, S; Yoldi-Petri, M E

    2017-11-16

    Continuous spikes and waves during slow sleep (CSWS) is an epileptic encephalopathy of childhood with a pattern of epileptiform discharges during sleep, which, if prolonged over time, produce severe neuropsychological impairment. Quantification of the paroxysms by means of a spike and wave index (SWI) > 85% establishes a presumptive diagnosis and allows early therapy to be started to prevent such impairment. To compare the results of the classic method for calculating the SWI against two proposals that optimise the relation between the analysis time employed and the diagnostic sensitivity. The nocturnal electroencephalographic registers of 17 patients with CSWS were studied. Two observers calculated the SWI with the classic method, as well as with two other methods, M2 and M3, first in the active phase and then in the remission phase. The time required by each method, the individual SWI values and the agreement between methods and observers were compared. With M3 two of the patients failed to reach the cut-off point of SWI > 85%. Agreement in the active phase of CSWS after M2 and M3 was 0.762 and 0.704, respectively, while in the remission phase it was 0.951 and 0.830. Inter-observer agreement exceeded 0.905 in all cases. The two abbreviated methods can be used in both the active and the remission phases, with a substantial reduction in the analysis time that is needed. Our results support the current tendency to consider SWI > 60% as suggestive of CSWS. Method M2 yields results that are closer to those of the classic method than those of M3.

  11. Thalamic abnormalities in children with continuous spike-wave during slow-wave sleep: An F-18-fluorodeoxyglucose positron emission tomography perspective.

    Science.gov (United States)

    Agarwal, Rajkumar; Kumar, Ajay; Tiwari, Vijay N; Chugani, Harry

    2016-02-01

    Thalamic injury has been implicated in the development of continuous spike-wave during slow-wave sleep (CSWS) in children with epilepsy. We studied thalamic abnormalities in children with CSWS using F-18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging. Twenty-three patients (12 male; mean age 9 years) with CSWS and normal thalami on brain magnetic resonance imaging (MRI) underwent FDG-PET. Thalamic glucose metabolism, represented by standardized uptake value normalized to whole brain (nSUV, RT for right thalamus and LT for left thalamus), and its asymmetry--absolute asymmetry index (AAI): ¦(RT-LT)¦*100/[(RT+LT)/2]--was calculated. These values were compared with those from 10 normal healthy controls (five female; mean age 11.1 years). Thalamic glucose metabolism was abnormal in 18 patients (78.3%). Thalamic nSUV was decreased (n = 6) or increased (n = 1) bilaterally in seven children without any asymmetry. Abnormal thalamic symmetry [AAI = 3.7-31.5% (0.8-3.3% in controls)] was seen in 11 children. Of these, six children had a unilateral thalamic metabolic abnormality (increased metabolism, n = 3 and decreased metabolism, n = 3), whereas 5 of 14 children had abnormal asymmetry index with bilaterally normal (n = 4) or increased (n = 1) thalamic metabolism. No clear association of thalamic metabolic abnormalities was seen with the stage of evolution of CSWS (prodromal, acute, or residual) or with the cortical FDG abnormalities. Functional thalamic abnormalities, both unilateral and bilateral, are frequently seen in patients with CSWS. FDG-PET is a sensitive and quantifiable modality to detect these changes. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

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

    Science.gov (United States)

    Cerri, Matteo; Del Vecchio, Flavia; Mastrotto, Marco; Luppi, Marco; Martelli, Davide; Perez, Emanuele; Tupone, Domenico; Zamboni, Giovanni; Amici, Roberto

    2014-01-01

    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.

  13. 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.

  14. Long-lasting silencing of orexin/hypocretin neurons using archaerhodopsin induces slow-wave sleep in mice.

    Science.gov (United States)

    Tsunematsu, Tomomi; Tabuchi, Sawako; Tanaka, Kenji F; Boyden, Edward S; Tominaga, Makoto; Yamanaka, Akihiro

    2013-10-15

    Orexin/hypocretin neurons have a crucial role in the regulation of sleep and wakefulness. Recent optogenetic studies revealed that the activation or inhibition of orexin neuronal activity affects the probability of sleep/wakefulness transition in the acute phase. To expand our understanding of how orexin neurons maintain wakefulness, we generated new transgenic mice in which orexin neurons expressed archaerhodopsin from Halorubrum strain TP009 (ArchT), a green light-driven neuronal silencer, using the tet-off system (orexin-tTA; TetO ArchT mice). Slice patch clamp recordings of ArchT-expressing orexin neurons demonstrated that long-lasting photic illumination was able to silence the activity of orexin neurons. We further confirmed that green light illumination for 1h in the dark period suppressed orexin neuronal activity in vivo using c-Fos expression. Continuous 1h silencing of orexin neurons in freely moving orexin-tTA; TetO ArchT mice during the night (the active period, 20:00-21:00) significantly increased total time spent in slow-wave sleep (SWS) and decreased total wake time. Additionally, photic inhibition increased sleep/wakefulness state transitions, which is also evident in animals lacking the prepro-orexin gene, orexin neurons, or functional orexin-2 receptors. However, continuous 1h photic illumination produced little effect on sleep/wakefulness states during the day (the inactive period, 12:00-13:00). These results suggest that orexin neuronal activity plays a crucial role in the maintenance of wakefulness especially in the active phase in mice. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Correlation between slow-wave myoelectric signals and mechanical contractions in the gastrointestinal tract: Advanced electromyographic method in rats.

    Science.gov (United States)

    Szucs, Kalman F; Nagy, Aniko; Grosz, Gyorgy; Tiszai, Zita; Gaspar, Robert

    Gastrointestinal motility disorders are presumed to be associated with abnormalities of the generation of slow-wave electric impulses. A requirement for the development of non-invasive clinical methods for the diagnosis of motility disorders is the identification of these signals. We set out to separate and characterize the signals from the various sections of the gastrointestinal tract and to detect changes in the smooth muscle electromyography (SEMG) signals. Partially resected (stomach-small intestine, stomach-large intestine or small and large intestine) or non-resected male SPRD rats were measured under deep anaesthesia. Bipolar thread and disk electrodes and strain gauge sensors were used for SEMG and the detection of mechanical contractions, respectively. The electric activity was characterized by cycle per minute (cpm) and power spectrum density maximum (PsDmax) W by fast Fourier transformation analysis. Contractions were evaluated by area under the curve analysis. The myoelectric signals of the stomach, ileum and caecum were at 3-5, 20-25 and 1-3cpm, respectively. Neostigmine increased (40-60%), while atropine decreased (30-50%) the PsDmax values. However, the cpm values remained unchanged. Linear regression revealed a good correlation between the PsDmax values and the smooth muscle contractions. Electric signals of the same character were recorded from the organ and from the abdominal surface. The change in PsDmax perfectly reflects the change in the contractions of the smooth muscle. These results may serve as the basis for non-invasive gastrointestinal measurements in experimental animals, which can be translated into clinical practice for motility studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. You’ll feel better in the morning: Slow wave activity and overnight mood regulation in interepisode bipolar disorder

    Science.gov (United States)

    Soehner, Adriane M.; Kaplan, Katherine A.; Saletin, Jared M.; Talbot, Lisa S.; Hairston, Ilana S.; Gruber, June; Eidelman, Polina; Walker, Matthew P.; Harvey, Allison G.

    2017-01-01

    Background Sleep disturbances are prominent correlates of acute mood episodes and inadequate recovery in bipolar disorder (BD), yet the mechanistic relationship between sleep physiology and mood remains poorly understood. Using a series of pre-sleep mood inductions and overnight sleep recording, this study examined the relationship between overnight mood regulation and a marker of sleep intensity (non-rapid eye movement sleep slow wave activity; NREM SWA) during the interepisode phase of BD. Methods Adults with interepisode BD type 1 (BD; n=20) and healthy adult controls (CTL; n=23) slept in the laboratory for a screening night, a neutral mood induction night (baseline), a happy mood induction night, and a sad mood induction night. NREM SWA (0.75–4.75Hz) was derived from overnight sleep EEG recordings. Overnight mood regulation was evaluated using an affect grid pleasantness rating post-mood induction (pre-sleep) and the next morning. Results Overnight mood regulation did not differ between groups following the sad or happy inductions. SWA did not significantly change for either group on the sad induction night compared to baseline. In BD only, SWA on the sad night was related to impaired overnight negative mood regulation. On the happy induction night, SWA increased relative to baseline in both groups, though SWA was not related to overnight mood regulation for either group. Conclusions These findings indicate that SWA disruption may play a role in sustaining negative mood state from the previous night in interepisode BD. However, positive mood state could enhance SWA in bipolar patients and healthy adults. PMID:28625231

  17. Restricting Time in Bed in Early Adolescence Reduces Both NREM and REM Sleep but Does Not Increase Slow Wave EEG

    Science.gov (United States)

    Campbell, Ian G.; Kraus, Amanda M.; Burright, Christopher S.; Feinberg, Irwin

    2016-01-01

    Study Objectives: School night total sleep time decreases across adolescence (9–18 years) by 10 min/year. This decline is comprised entirely of a selective decrease in NREM sleep; REM sleep actually increases slightly. Decreasing sleep duration across adolescence is often attributed to insufficient time in bed. Here we tested whether sleep restriction in early adolescence produces the same sleep stage changes observed on school nights across adolescence. Methods: All-night sleep EEG was recorded in 76 children ranging in age from 9.9 to 14.0 years. Each participant kept 3 different sleep schedules that consisted of 3 nights of 8.5 h in bed followed by 4 nights of either 7, 8.5, or 10 h in bed. Sleep stage durations and NREM delta EEG activity were compared across the 3 time in bed conditions. Results: Shortening time in bed from 10 to 7 hours reduced sleep duration by approximately 2 hours, roughly equal to the decrease in sleep duration we recorded longitudinally across adolescence. However, sleep restriction significantly reduced both NREM (by 83 min) and REM (by 47 min) sleep. Sleep restriction did not affect NREM delta EEG activity. Conclusions: Our findings suggest that the selective NREM reduction and the small increase in REM we observed longitudinally across 9–18 years are not produced by sleep restriction. We hypothesize that the selective NREM decline reflects adolescent brain maturation (synaptic elimination) that reduces the need for the restorative processes of NREM sleep. Citation: Campbell IG, Kraus AM, Burright CS, Feinberg I. Restricting time in bed in early adolescence reduces both NREM and REM sleep but does not increase slow wave EEG. SLEEP 2016;39(9):1663–1670. PMID:27397569

  18. 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

  19. 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 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 maintenance and subjective sleep quality under placebo and gaboxadol (p maintenance.

  20. Effects of Acoustic Waves on Stick—Slip Behavior in Sheared Granular Media With Implications to Dynamic Earthquake Triggering and Slow Slip

    Science.gov (United States)

    Johnson, Paul; Marone, Chris; Knuth, Matt; Kaproth, Bryan; Carpenter, Brett; Behringer, Bob; Guyer, Robert; Le Bas, Pierre-Yves; Griffa, Michele; Carmeliet, Jan

    2010-05-01

    To better understand the physics of dynamic triggering and the influence of dynamic stressing on earthquake recurrence, we are conducting laboratory studies of stick—slip in granular media with and without applied acoustic waves. In our 3-D experiments, glass beads are used to simulate granular fault zone wear material, sheared in a double-direct configuration under constant normal stress, while subject to transient or continuous perturbations by acoustic waves. We find that the horizontal stress applied plays a crucial role in the response of the glass beads to applied waves. Under smaller normal stress (2MPa), and subject to wave amplitudes of >10-6 strain, we observe induced slow (silent) slip and tremor. Under moderate normal stress (4 MPa) and subject to >10-6 strain amplitude we observe both instantaneous and delayed triggering. Waves also cause significant disruption in the recurrence rate. The effects of waves are observed for many major-event cycles after wave excitation ceases, indicating a strain memory of waves in the granular material. Under slightly larger horizontal stress (5MPa), if strain amplitudes exceed 10-6, we observe instantaneous triggering followed by slow dynamics—the shear modulus recovers linearly with the-logarithm-of-time back to equilibrium. Slow dynamics is a classical elastic nonlinear (anelastic) behavior observed in acoustical experiments with rock samples in the lab as well as in Earth. Wave-induced disruption of periodic stick—slip is linked to failure of granular force chains. In 2-D experiments we are applying photoelastic discs in stick—slip measurements in order to visualize the evolution of the force chain network. Photoelastic measurements provide insight into failure, and in particular small adjustments in the force chains network that presage failure. A phenomenological model similar to Knopoff-Burridge shows the same general behaviors as well. In a companion paper, we show model results emplying a DEM approach

  1. Nonlinear dynamical systems effects of homeopathic remedies on multiscale entropy and correlation dimension of slow wave sleep EEG in young adults with histories of coffee-induced insomnia.

    Science.gov (United States)

    Bell, Iris R; Howerter, Amy; Jackson, Nicholas; Aickin, Mikel; Bootzin, Richard R; Brooks, Audrey J

    2012-07-01

    Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG. Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stages 3 and 4 slow wave sleep EEG sampled in artifact-free 2-min segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects. MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings. Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns. Copyright © 2012 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

  2. Efficiency enhancement of slow-wave electron-cyclotron maser by a second-order shaping of the magnetic field in the low-gain limit

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Si-Jia; Zhang, Yu-Fei; Wang, Kang [School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Yong-Ming [Information Science and Engineering College, XinJiang University, Urumqi XinJiang 830046 (China); Jing, Jian, E-mail: jingjian@mail.buct.edu.cn [School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)

    2017-03-15

    Based on the anomalous Doppler effect, we put forward a proposal to enhance the conversion efficiency of the slow-wave electron cyclotron masers (ECM) under the resonance condition. Compared with previous studies, we add a second-order shaping term in the guild magnetic field. Theoretical analyses and numerical calculations show that it can enhance the conversion efficiency in the low-gain limit. The case of the initial velocity spread of electrons satisfying the Gaussian distribution is also analysed numerically.

  3. Increased Stability and Breakdown of Brain Effective Connectivity During Slow-Wave Sleep: Mechanistic Insights from Whole-Brain Computational Modelling

    OpenAIRE

    Jobst, Beatrice M; Hindriks, Rikkert; Laufs, Helmut; Tagliazucchi, E; Hahn, Gerald; Ponce-Alvarez, Adrián; Stevner, Angus B. A.; Kringelbach, Morten L.; Deco, Gustavo

    2017-01-01

    Recent research has found that the human sleep cycle is characterised by changes in spatiotemporal patterns of brain activity. Yet, we are still missing a mechanistic explanation of the local neuronal dynamics underlying these changes. We used whole-brain computational modelling to study the differences in global brain functional connectivity and synchrony of fMRI activity in healthy humans during wakefulness and slow-wave sleep. We applied a whole-brain model based on the normal form of a su...

  4. Comparison of shear-wave slowness profiles at 10 strong-motion sites from noninvasive SASW measurements and measurements made in boreholes

    Science.gov (United States)

    Brown, L.T.; Boore, D.M.; Stokoe, K.H.

    2002-01-01

    The spectral-analysis-of-surface-waves (SASW) method is a relatively new in situ method for determining shear-wave slownesses. All measurements are made on the ground surface, making it much less costly than methods that require boreholes. The SASW method uses a number of active sources (ranging from a commercial Vibroseis truck to a small handheld hammer for the study conducted here) and different receiver spacings to map a curve of apparent phase velocity versus frequency. With the simplifying assumption that the phase velocities correspond to fundamental mode surface waves, forward modeling yields an estimate of the sub-surface shear-wave slownesses. To establish the reliability of this indirect technique, we conducted a blind evaluation of the SASW method. SASW testing was performed at 10 strong-motion stations at which borehole seismic measurements were previously or subsequently made; if previously made, the borehole results were not used for the interpretation of the SASW data, and vice-versa. Comparisons of the shear-wave slownesses from the SASW and borehole measurements are generally very good. The differences in predicted ground-motion amplifications are less than about 15% for most frequencies. In addition, both methods gave the same NEHRP site classification for seven of the sites. For the other three sites the average velocities from the downhole measurements were only 5-13 m/sec larger than the velocity defining the class C/D boundary. This study demonstrates that in many situations the SASW method can provide subsurface information suitable for site response predictions.

  5. Distinct associations between energy balance and the sleep characteristics slow wave sleep and rapid eye movement sleep.

    Science.gov (United States)

    Rutters, F; Gonnissen, H K; Hursel, R; Lemmens, S G; Martens, E A; Westerterp-Plantenga, M S

    2012-10-01

    Epidemiologically, an inverse relationship between body mass index (BMI) and sleep duration is observed. Intra-individual variance in the amount of slow wave sleep (SWS) or rapid eye movement (REM) sleep has been related to variance of metabolic and endocrine parameters, which are risk factors for the disturbance of energy balance (EB). To investigate inter-individual relationships between EB (EB= energy intake-energy expenditure∣, MJ/24 h), SWS or REM sleep, and relevant parameters in normal-weight men during two 48 h stays in the controlled environment of a respiration chamber. A total of 16 men (age 23±3.7 years, BMI 23.9±1.9 kg m(-2)) stayed in the respiration chamber twice for 48 h to assure EB. Electroencephalography was used to monitor sleep (2330-0730 hrs). Hunger and fullness were scored by visual analog scales; mood was determined by State Trait Anxiety Index-state and food reward by liking and wanting. Baseline blood and salivary samples were collected before breakfast. Subjects were fed in EB, except for the last dinner, when energy intake was ad libitum. The subjects slept on average 441.8±49 min per night, and showed high within-subject reliability for the amount of SWS and REM sleep. Linear regression analyses showed that EB was inversely related to the amount of SWS (r=-0.43, Phunger, reward, stress and orexigenic hormone concentrations were related to overeating, as well as to the amount of SWS and REM sleep, however, after inclusion of these parameters in a multiple regression, the amount of SWS and REM sleep did not add to the explained variance of EB, which suggests that due to their individual associations, these EB parameters are mediator variables. A positive EB due to overeating, was explained by a smaller amount of SWS and higher amount of REM sleep, mediated by hunger, fullness, State Trait Anxiety Index-state scores, glucose/insulin ratio, and ghrelin and cortisol concentrations.

  6. Dissociating the contributions of slow-wave sleep and rapid eye movement sleep to emotional item and source memory.

    Science.gov (United States)

    Groch, S; Zinke, K; Wilhelm, I; Born, J

    2015-07-01

    Sleep benefits the consolidation of emotional memories, and this influence is commonly attributed to the rapid eye movement (REM) stage of sleep. However, the contributions of sleep stages to memory for an emotional episode may differ for the event per se (i.e., item memory), and the context in which it occurred (source memory). Here, we examined the effects of slow wave sleep (SWS) and REM sleep on the consolidation of emotionally negative and neutral item (picture recognition) and source memory (recall of picture-location and picture-frame color association) in humans. In Study 1, the participants (n=18) learned 48 negative and 48 neutral pictures which were presented at specific locations and preceded by colored frames that had to be associated with the picture. In a within-subject design, learning was either followed by a 3-h early-night SWS-rich or by a late-night REM sleep-rich retention interval, then retrieval was tested. Only after REM-rich sleep, and not after SWS-rich sleep, was there a significant emotional enhancement, i.e., a significantly superior retention of emotional over neutral pictures. On the other hand, after SWS-rich sleep the retention of picture-frame color associations was better than after REM-rich sleep. However, this benefit was observed only for neutral pictures; and it was completely absent for the emotional pictures. To examine whether this absent benefit reflected a suppressive effect of emotionality on associations of minor task relevance, in Study 2 we manipulated the relevance of the picture-frame color association by combining it with information about monetary reward, following otherwise comparable procedures. Here, rewarded picture-frame color associations were equally well retained over SWS-rich early sleep no matter if the frames were associated with emotional or neutral pictures. Results are consistent with the view that REM sleep favors the emotional enhancement of item memory whereas SWS appears to contribute primarily

  7. Dust ion acoustic waves in four component magnetized dusty plasma with effect of slow rotation and superthermal electrons

    Science.gov (United States)

    Farooq, M.; Ahmad, Mushtaq

    2017-12-01

    Dust ion acoustic waves are investigated in four component magneto-rotating dusty plasma comprising opposite polarity dust grains, ions, and nonthermal electrons using the concept of one fluid and two fluid models. The Zakharov-Kuznetsov equation is derived using the reductive perturbation technique to study the nonlinear solitary wave structures. The numerical results show that the superthermality of electrons affects both amplitude and width of the solitary waves while the rotational frequency has a small impression on the width. It is shown that the solitary wave changes its potential from positive to negative at a critical value of the superthermal parameter. It is also observed that the inertial role of dust grains flourishes the effect of rotational frequency and also changes the critical value of the superthermal parameter where the positive/negative potential solitary waves exist.

  8. Cycle-Triggered Cortical Stimulation during Slow Wave Sleep Facilitates Learning a BMI Task: A Case Report in a Non-Human Primate.

    Science.gov (United States)

    Rembado, Irene; Zanos, Stavros; Fetz, Eberhard E

    2017-01-01

    Slow wave sleep (SWS) has been identified as the sleep stage involved in consolidating newly acquired information. A growing body of evidence has shown that delta (1-4 Hz) oscillatory activity, the characteristic electroencephalographic signature of SWS, is involved in coordinating interaction between the hippocampus and the neocortex and is thought to take a role in stabilizing memory traces related to a novel task. This case report describes a new protocol that uses neuroprosthetics training of a non-human primate to evaluate the effects of surface cortical electrical stimulation triggered from SWS cycles. The results suggest that stimulation phase-locked to SWS oscillatory activity promoted learning of the neuroprosthetic task. This protocol could be used to elucidate mechanisms of synaptic plasticity underlying off-line learning during sleep and offers new insights into the role of brain oscillations in information processing and memory consolidation.

  9. Polysomnographic measures of sleep in cocaine dependence and alcohol dependence: Implications for age‐related loss of slow wave, stage 3 sleep

    Science.gov (United States)

    Bjurstrom, Martin F.; Olmstead, Richard

    2016-01-01

    Abstract Background and aims Sleep disturbance is a prominent complaint in cocaine and alcohol dependence. This controlled study evaluated differences of polysomnographic (PSG) sleep in cocaine‐ and alcohol‐dependent subjects, and examined whether substance dependence interacts with age to alter slow wave sleep and rapid eye movement (REM) sleep. Design Cross‐sectional comparison. Setting Los Angeles and San Diego, CA, USA. Participants Abstinent cocaine‐dependent subjects (n = 32), abstinent alcohol‐dependent subjects (n = 73) and controls (n = 108); mean age 40.3 years recruited 2005–12. Measurements PSG measures of sleep continuity and sleep architecture primary outcomes of Stage 3 sleep and REM sleep. Covariates included age, ethnicity, education, smoking, body mass index and depressive symptoms. Findings Compared with controls, both groups of substance dependent subjects showed loss of Stage 3 sleep (P < 0.001). A substance dependence × age interaction was found in which both cocaine‐ and alcohol‐dependent groups showed loss of Stage 3 sleep at an earlier age than controls (P < 0.05 for all), and cocaine‐dependent subjects showed loss of Stage 3 sleep at an earlier age than alcoholics (P < 0.05). Compared with controls, REM sleep was increased in both substance‐dependent groups (P < 0.001), and cocaine and alcohol dependence were associated with earlier age‐related increase in REM sleep (P < 0.05 for all). Conclusions Cocaine and alcohol dependence appear to be associated with marked disturbances of sleep architecture, including increased rapid eye movement sleep and accelerated age‐related loss of slow wave, Stage 3 sleep. PMID:26749502

  10. Oscillating Square Wave Transcranial Direct Current Stimulation (tDCS) Delivered During Slow Wave Sleep Does Not Improve Declarative Memory More Than Sham: A Randomized Sham Controlled Crossover Study.

    Science.gov (United States)

    Sahlem, Gregory L; Badran, Bashar W; Halford, Jonathan J; Williams, Nolan R; Korte, Jeffrey E; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L; Runion, Jennifer; Bachman, David L; Uhde, Thomas W; Borckardt, Jeffery J; George, Mark S

    2015-01-01

    A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517 mA/cm(2), and oscillated between zero and maximal current at a frequency of 0.75 Hz. Stimulation occurred during five-five minute blocks with 1-min inter-block intervals (25 min total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1 ± 3.0 SD more associations) (sham = 3.8 ± 3.1 SD more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6 ± 2.7 SD correctly typed sequences) compared to sham stimulation (2.3 ± 2.2 SD correctly typed

  11. Electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) syndrome in children: An electroclinical evaluation according to the EEG patterns.

    Science.gov (United States)

    Gencpinar, Pinar; Dundar, Nihal Olgac; Tekgul, Hasan

    2016-08-01

    The aim of this study was to describe the electroclinical spectrum in children with electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) syndrome according to the EEG patterns. Clinical data of 44 patients with ESES/CSWS syndrome who were treated and followed at least two years were analyzed. Records of EEGs of patients were reevaluated to determine two aspects of the ESES pattern: (1) the spike-wave index (SWI) on the NREM sleep EEG (Group I: typical vs. atypical ESES pattern (33/11 patients)) and (2) the area of maximum amplitude of continuous epileptic activity (Group II: anterior vs. posterior ESES pattern (33/11 patients)). Symptomatic etiology was more defined in patients with the typical ESES pattern (40%) than the group with the atypical ESES pattern (9%) by a factor of four. All patients were receiving at least two antiepileptic drug (AED) treatments. Eighteen patients (41%) received AEDs plus ACTH therapy. Complete disappearance of the ESES pattern on the EEG was observed in 18 patients (41%), more than 50% reduction was observed in five patients (11%), less than 50% reduction was observed in eight patients (18%), and no response was observed in five patients (11%). No significant difference was found when comparing the groups in terms of reduction of seizures and the SWI. Seizure outcome at the two-year follow-up was similar between the group with ESES treated with AEDs plus ACTH and the group with ESES treated with AEDs without ACTH therapy. This study demonstrated that the rate of the SWI (typical vs. atypical ESES) and the maximum amplitude of the ESES pattern (anterior vs. posterior) have no significant correlation with seizure control and reduction of the SWI on the EEG in children with ESES syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. 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.

  13. β oscillation during slow wave sleep and rapid eye movement sleep in the electroencephalogram of a transgenic mouse model of Huntington's disease.

    Directory of Open Access Journals (Sweden)

    Yannick Jeantet

    Full Text Available STUDY OBJECTIVES: To search for early abnormalities in electroencephalogram (EEG during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington's disease (HD. DESIGN: In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. MEASUREMENTS AND RESULTS: Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours, beginning at 9-11 weeks (presymptomatic period through 6-7 months (symptomatic period. Recording data revealed a unique β rhythm (20-35 Hz, present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM sleep. CONCLUSIONS: In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep.

  14. β oscillation during slow wave sleep and rapid eye movement sleep in the electroencephalogram of a transgenic mouse model of Huntington's disease.

    Science.gov (United States)

    Jeantet, Yannick; Cayzac, Sebastien; Cho, Yoon H

    2013-01-01

    To search for early abnormalities in electroencephalogram (EEG) during sleep which may precede motor symptoms in a transgenic mouse model of hereditary neurodegenerative Huntington's disease (HD). In the R6/1 transgenic mouse model of HD, rhythmic brain activity in EEG recordings was monitored longitudinally and across vigilance states through the onset and progression of disease. Mice with chronic electrode implants were recorded monthly over wake-sleep cycles (4 hours), beginning at 9-11 weeks (presymptomatic period) through 6-7 months (symptomatic period). Recording data revealed a unique β rhythm (20-35 Hz), present only in R6/1 transgenic mice, which evolves in close parallel with the disease. In addition, there was an unusual relationship between this β oscillation and vigilance states: while nearly absent during the active waking state, the β oscillation appeared with drowsiness and during slow wave sleep (SWS) and, interestingly, strengthened rather than dissipating when the brain returned to an activated state during rapid eye movement (REM) sleep. In addition to providing a new in vivo biomarker and insight into Huntington's disease pathophysiology, this serendipitous observation opens a window onto the rarely explored neurophysiology of the cortico-basal ganglia circuit during SWS and REM sleep.

  15. Age-related changes in slow wave activity rise time and NREM sleep EEG with and without zolpidem in healthy young and older adults

    Science.gov (United States)

    Chinoy, Evan D.; Frey, Danielle J.; Kaslovsky, Daniel N.; Meyer, Francois G.; Wright, Kenneth P.

    2015-01-01

    Objective Whether there are age-related changes in slow wave activity (SWA) rise time, a marker of homeostatic sleep drive, is unknown. Additionally, although sleep medication use is highest among older adults, the quantitative electroencephalographic (EEG) profile of the most commonly prescribed sleep medication, zolpidem, in older adults is also unknown. We therefore quantified age-related and regional brain differences in sleep EEG with and without zolpidem. Methods Thirteen healthy young adults aged 21.9 ± 2.2 years and 12 healthy older adults aged 67.4 ± 4.2 years participated in a randomized, double-blind, within-subject study that compared placebo to 5 mg zolpidem. Results Older adults showed a smaller rise in SWA and zolpidem increased age-related differences in SWA rise time such that age differences were observed earlier after latency to persistent sleep. Age-related differences in EEG power differed by brain region. Older, but not young, adults showed zolpidem-dependent reductions in theta and alpha frequencies. Zolpidem decreased stage 1 in older adults and did not alter other age-related sleep architecture parameters. Conclusions SWA findings provide additional support for reduced homeostatic sleep drive or reduced ability to respond to sleep drive with age. Consequences of reduced power in theta and alpha frequencies in older adults remain to be elucidated. PMID:24980066

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Rosini, Francesca; Federighi, Pamela; Pretegiani, Elena; Piu, Pietro; Leigh, R John; Serra, Alessandro; Federico, Antonio; Rufa, Alessandra

    2013-01-01

    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.

  19. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  20. Fully Distributed Tunable Bandpass Filter Based on Ba0.5Sr0.5TiO3 Thin-Film Slow-Wave Structure

    Directory of Open Access Journals (Sweden)

    Sébastien L. Delprat

    2011-01-01

    Full Text Available This paper presents simulation and measurement results of fully distributed tunable coplanar bandpass filters (BPFs with center frequencies around 6 GHz that make use of ferroelectric Barium Strontium Titanate (BaxSr1−xTiO3 or BST-x thin film as tunable material. The two experimental bandpass filters tested are based on a novel frequency-agile structure composed of cascaded half wavelength slow-wave resonators (2 poles and three coupled interdigital capacitors (IDCs optimized for bias voltage application. Devices with gap dimensions of 10 and 3 μm are designed and fabricated with a two-step process on polycrystalline Ba0.5Sr0.5TiO3 thin films deposited on alumina substrate. A frequency tunability of 9% is obtained for the 10 μm gap structure at ±30 V with 7 dB insertion loss (the BST dielectric tunability being 26% with 0.04 loss tangent for this gap size. When the structure gap is reduced to 3 μm the center frequency shifts with a constant 9 dB insertion loss from 6.95 GHz at 0 V to 9.05 GHz at ±30 V, thus yielding a filter tunability of 30% (the BST dielectric tunability being 60% with 0.04 loss tangent for this gap size, a performance comparable to some extent to localized or lumped element BPFs operating at microwave frequency (>2 GHz.

  1. Glucose Induces Slow-Wave Sleep by Exciting the Sleep-Promoting Neurons in the Ventrolateral Preoptic Nucleus: A New Link between Sleep and Metabolism.

    Science.gov (United States)

    Varin, Christophe; Rancillac, Armelle; Geoffroy, Hélène; Arthaud, Sébastien; Fort, Patrice; Gallopin, Thierry

    2015-07-08

    Sleep-active neurons located in the ventrolateral preoptic nucleus (VLPO) play a crucial role in the induction and maintenance of slow-wave sleep (SWS). However, the cellular and molecular mechanisms responsible for their activation at sleep onset remain poorly understood. Here, we test the hypothesis that a rise in extracellular glucose concentration in the VLPO can promote sleep by increasing the activity of sleep-promoting VLPO neurons. We find that infusion of a glucose concentration into the VLPO of mice promotes SWS and increases the density of c-Fos-labeled neurons selectively in the VLPO. Moreover, we show in patch-clamp recordings from brain slices that VLPO neurons exhibiting properties of sleep-promoting neurons are selectively excited by glucose within physiological range. This glucose-induced excitation implies the catabolism of glucose, leading to a closure of ATP-sensitive potassium (KATP) channels. The extracellular glucose concentration monitors the gating of KATP channels of sleep-promoting neurons, highlighting that these neurons can adapt their excitability according to the extracellular energy status. Together, these results provide evidence that glucose may participate in the mechanisms of SWS promotion and/or consolidation. Although the brain circuitry underlying vigilance states is well described, the molecular mechanisms responsible for sleep onset remain largely unknown. Combining in vitro and in vivo experiments, we demonstrate that glucose likely contributes to sleep onset facilitation by increasing the excitability of sleep-promoting neurons in the ventrolateral preoptic nucleus (VLPO). We find here that these neurons integrate energetic signals such as ambient glucose directly to regulate vigilance states accordingly. Glucose-induced excitation of sleep-promoting VLPO neurons should therefore be involved in the drowsiness that one feels after a high-sugar meal. This novel mechanism regulating the activity of VLPO neurons reinforces the

  2. The dream-lag effect: Selective processing of personally significant events during Rapid Eye Movement sleep, but not during Slow Wave Sleep.

    Science.gov (United States)

    van Rijn, E; Eichenlaub, J-B; Lewis, P A; Walker, M P; Gaskell, M G; Malinowski, J E; Blagrove, M

    2015-07-01

    Incorporation of details from waking life events into Rapid Eye Movement (REM) sleep dreams has been found to be highest on the night after, and then 5-7 nights after events (termed, respectively, the day-residue and dream-lag effects). In experiment 1, 44 participants kept a daily log for 10 days, reporting major daily activities (MDAs), personally significant events (PSEs), and major concerns (MCs). Dream reports were collected from REM and Slow Wave Sleep (SWS) in the laboratory, or from REM sleep at home. The dream-lag effect was found for the incorporation of PSEs into REM dreams collected at home, but not for MDAs or MCs. No dream-lag effect was found for SWS dreams, or for REM dreams collected in the lab after SWS awakenings earlier in the night. In experiment 2, the 44 participants recorded reports of their spontaneously recalled home dreams over the 10 nights following the instrumental awakenings night, which thus acted as a controlled stimulus with two salience levels, high (sleep lab) and low (home awakenings). The dream-lag effect was found for the incorporation into home dreams of references to the experience of being in the sleep laboratory, but only for participants who had reported concerns beforehand about being in the sleep laboratory. The delayed incorporation of events from daily life into dreams has been proposed to reflect REM sleep-dependent memory consolidation. However, an alternative emotion processing or emotional impact of events account, distinct from memory consolidation, is supported by the finding that SWS dreams do not evidence the dream-lag effect. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  3. A review of short naps and sleep inertia: do naps of 30 min or less really avoid sleep inertia and slow-wave sleep?

    Science.gov (United States)

    Hilditch, Cassie J; Dorrian, Jillian; Banks, Siobhan

    2017-04-01

    Napping is a widely used countermeasure to sleepiness and impaired performance caused by sleep loss and circadian pressure. Sleep inertia, the period of grogginess and impaired performance experienced after waking, is a potential side effect of napping. Many industry publications recommend naps of 30 min or less to avoid this side effect. However, the evidence to support this advice is yet to be thoroughly reviewed. Electronic databases were searched, and defined criteria were applied to select articles for review. The review covers literature on naps of 30 min or less regarding (a) sleep inertia, (b) slow-wave sleep (SWS) and (c) the relationship between sleep inertia and SWS. The review found that although the literature on short afternoon naps is relatively comprehensive, there are very few studies on naps of 30 min or less at night. Studies have mixed results regarding the onset of SWS and the duration and severity of sleep inertia following short naps, making guidelines regarding their use unclear. The varying results are likely due to differing sleep/wake profiles before the nap of interest and the time of the day at waking. The review highlights the need to have more detailed guidelines about the implementation of short naps according to the time of the day and prior sleep/wake history. Without this context, such a recommendation is potentially misleading. Further research is required to better understand the interactions between these factors, especially at night, and to provide more specific recommendations. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Slow Meteors

    Science.gov (United States)

    Dubs, Martin; Sposetti, Stefano; Spinner, Roger; Booz, Beat

    2017-04-01

    Slow meteors are studied with video observations and spectroscopy. A comparison of their orbits and spectra points to a common origin. Although they do not belong to some meteor stream, they deserve to be studied in more detail. The present paper tries to make a first attempt to characterize the common properties of this class of meteors.

  5. Slow Learner.

    Science.gov (United States)

    Howie, Mark

    2002-01-01

    Discusses the author's success in teaching English. Describes his experiences in achievement, including what has sometimes felt like a slow and even painful process of professional development. Presents an outline of a unit that illustrates a movement through approaches: from personal growth type activities, to post-structuralist and critical…

  6. Effects of Late-Night Training on "Slow-Wave Sleep Episode" and Hour-by-Hour Derived Nocturnal Cardiac Autonomic Activity in Female Soccer Players.

    Science.gov (United States)

    Costa, Júlio A; Brito, João; Nakamura, Fábio Y; Oliveira, Eduardo M; Rebelo, António N

    2018-01-18

    To assess the sensitivity of nocturnal heart rate variability (HRV) monitoring methods to the effects of late-night soccer training sessions in female athletes. Eleven female soccer players competing in the 1 st division of the Portuguese soccer league wore HR monitors during night-sleep throughout a one-week competitive in-season microcycle, after late-night training sessions (n = 3) and rest days (n = 3). HRV was analyzed through "slow-wave sleep episode" (SWSE; 10 min duration) and "hour-by-hour" (all the RR intervals recorded throughout the hours of sleep). Training load was quantified by session rating of perceived exertion (sRPE: 281.8 ± 117.9 to 369.0 ± 111.7 a.u.) and training impulse (TRIMP: 77.5 ± 36.5 to 110.8 ± 31.6 a.u.), added to subjective well-being ratings (Hopper index: 11.6 ± 4.4 to 12.8 ± 3.2 a.u.). These variables were compared between training and rest days using repeated measures ANOVA. The ln-transformed SWSE cardiac autonomic activity (lnRMSSD varying between 3.92 ± 0.57 and 4.20 ± 0.60 ms; η p 2 = 0.16 [0.01-0.26]), lnHF, lnLF, lnSD1 and lnSD2 and the non-transformed LF/HF were not different among night-training session days and resting days (P > 0.05). Considering the hour-by-hour method (lnRMSSD varying between 4.05 ± 0.35 and 4.33 ± 0.32 ms; η p 2 = 0.46 [0.26-0.52]), lnHF, lnLF, lnSD1 and lnSD2 and the non-transformed LF/HF were not different among night-training session days and resting days (P > 0.05). Late-night soccer training does not seem to affect nocturnal SWSE and "hour-by-hour" HRV indices in highly-trained athletes.

  7. Ocular-Motor Profile and Effects of Memantine in a Familial Form of Adult Cerebellar Ataxia with Slow Saccades and Square Wave Saccadic Intrusions: e69522

    National Research Council Canada - National Science Library

    Francesca Rosini; Pamela Federighi; Elena Pretegiani; Pietro Piu; R John Leigh; Alessandro Serra; Antonio Federico; Alessandra Rufa

    2013-01-01

    ...). 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...

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

    National Research Council Canada - National Science Library

    Rosini, Francesca; Federighi, Pamela; Pretegiani, Elena; Piu, Pietro; Leigh, R John; Serra, Alessandro; Federico, Antonio; Rufa, Alessandra

    2013-01-01

    ...). 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...

  9. 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

    OpenAIRE

    Edgar Osuna S; Fouzia Siddiqui; Vanegas, Marco A.; Walters, Arthur S.; Sudhansu Chokroverty

    2008-01-01

    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...

  10. 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.

  11. Transabdominal ultrasonography of the small bowel.

    Science.gov (United States)

    Kralik, Rudolf; Trnovsky, Peter; Kopáčová, Marcela

    2013-01-01

    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.

  12. Daily bowel care program

    Science.gov (United States)

    ... gov/ency/patientinstructions/000133.htm Daily bowel care program To use the sharing features on this page, ... Work with your health care provider. Basic Bowel Program Keeping active helps prevent constipation. Try to walk, ...

  13. 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 ...

  14. Frequent Bowel Movements

    Science.gov (United States)

    ... 2017. Irritable bowel syndrome (IBS). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome. Accessed Nov. 15, 2017. Nov. 18, 2017 Original article: http://www.mayoclinic.org/symptoms/frequent-bowel- ...

  15. 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...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  16. 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....

  17. Slowing Ocean Acidification

    Science.gov (United States)

    Bravo, A.

    2016-12-01

    Currently our ocean's pH is 8.1, a decrease from 8.2 in the past 200 years since the beginning of the industrial revolution. The ocean absorbs about a third of the carbon dioxide (CO2) from the atmosphere, which is helpful to us, since reducing the amount of CO2 in the atmosphere shows global warming. However, what is the impact of all that CO2 on the ocean? I evaluated the effect of acidic water on bivalves, and found that the shells were broken down with exposure to increased acidity. I am concerned that continued ocean acidification will impact organisms that are unable to adapt to the changing ocean chemistry. While the US currently invests in alternative forms of energy including solar and wind, approximately 66% of our energy comes from sources that are releasing CO2 into the atmosphere. I want to explore the potential of wave energy as another form of renewable energy. When wind blows over the surface of the ocean, it creates a wave. Could this wave energy be a consistent clean energy source? Could a strategy to slow and reverse ocean acidification be found in the ocean?

  18. 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....

  19. 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.

  20. Bowel Diseases and Kidneys

    Directory of Open Access Journals (Sweden)

    A.E. Dorofeiev

    2015-09-01

    Full Text Available This review of contemporary publications analyzes the prevalence of combinations of bowel and renal diseases. Special attention is paid to the problem of correlation between bowel diseases and urolithiasis. We consider the possible pathogenic mechanisms of lesions, such as genetically determined violations of intestinal absorption and secretion, changes in the intestinal microbiota, systemic inflammatory response, water and electrolyte disturbances.

  1. Generation and evolution of interplanetary slow shocks

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    1996-04-01

    Full Text Available It is well known that most MHD shocks observed within 1 AU are MHD fast shocks. Only a very limited number of MHD slow shocks are observed within 1 AU. In order to understand why there are only a few MHD slow shocks observed within 1 AU, we use a one-dimensional, time-dependent MHD code with an adaptive grid to study the generation and evolution of interplanetary slow shocks (ISS in the solar wind. Results show that a negative, nearly square-wave perturbation will generate a pair of slow shocks (a forward and a reverse slow shock. In addition, the forward and the reverse slow shocks can pass through each other without destroying their characteristics, but the propagating speeds for both shocks are decreased. A positive, square-wave perturbation will generate both slow and fast shocks. When a forward slow shock (FSS propagates behind a forward fast shock (FFS, the former experiences a decreasing Mach number. In addition, the FSS always disappears within a distance of 150R⊙ (where R⊙ is one solar radius from the Sun when there is a forward fast shock (with Mach number ≥1.7 propagating in front of the FSS. In all tests that we have performed, we have not discovered that the FSS (or reverse slow shock evolves into a FFS (or reverse fast shock. Thus, we do not confirm the FSS-FFS evolution as suggested by Whang (1987.

  2. Inflammatory Bowel Disease (For Teens)

    Science.gov (United States)

    ... Protecting Your Online Identity and Reputation ADHD Medicines Inflammatory Bowel Disease KidsHealth > For Teens > Inflammatory Bowel Disease Print A ... en español Enfermedad inflamatoria del intestino What Is Inflammatory Bowel Disease? Inflammatory bowel disease (IBD) is a condition that ...

  3. Vedolizumab in pediatric inflammatory bowel disease

    DEFF Research Database (Denmark)

    Ledder, Oren; Assa, Amit; Levine, Arie

    2017-01-01

    Background: Vedolizumab, an anti-integrin antibody, has proven to be effective in adults with Inflammatory Bowel Disease (IBD), but the data in pediatrics are limited. We describe the short-term effectiveness and safety of vedolizumab in a European multi-center pediatric IBD cohort. Method: Retro...... was safe and effective in this cohort of pediatric refractory IBD. These data support previous findings of slow induction rate of vedolizumab in CD and a trend to be less effective compared to patients with UC.......Background: Vedolizumab, an anti-integrin antibody, has proven to be effective in adults with Inflammatory Bowel Disease (IBD), but the data in pediatrics are limited. We describe the short-term effectiveness and safety of vedolizumab in a European multi-center pediatric IBD cohort. Method...

  4. Bowel transit time

    Science.gov (United States)

    You will be asked to swallow 2 gelatin capsules filled with a colored food dye. You take these capsules with a meal. Afterwards, you observe your bowel movements and write down how long it takes for the ...

  5. 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....... The possibility of exciting the waves in different radial regions is demonstrated....

  6. Inflammatory Bowel Disease (For Children)

    Science.gov (United States)

    ... Bowel Disease Print A A A en español Enfermedad inflamatoria del intestino What Is Inflammatory Bowel Disease? ... of IBD? There are two kinds of IBD: Crohn's disease and ulcerative colitis (say: UL-sur-uh- ...

  7. Generation and evolution of interplanetary slow shocks

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    Full Text Available It is well known that most MHD shocks observed within 1 AU are MHD fast shocks. Only a very limited number of MHD slow shocks are observed within 1 AU. In order to understand why there are only a few MHD slow shocks observed within 1 AU, we use a one-dimensional, time-dependent MHD code with an adaptive grid to study the generation and evolution of interplanetary slow shocks (ISS in the solar wind. Results show that a negative, nearly square-wave perturbation will generate a pair of slow shocks (a forward and a reverse slow shock. In addition, the forward and the reverse slow shocks can pass through each other without destroying their characteristics, but the propagating speeds for both shocks are decreased. A positive, square-wave perturbation will generate both slow and fast shocks. When a forward slow shock (FSS propagates behind a forward fast shock (FFS, the former experiences a decreasing Mach number. In addition, the FSS always disappears within a distance of 150R (where R is one solar radius from the Sun when there is a forward fast shock (with Mach number ≥1.7 propagating in front of the FSS. In all tests that we have performed, we have not discovered that the FSS (or reverse slow shock evolves into a FFS (or reverse fast shock. Thus, we do not confirm the FSS-FFS evolution as suggested by Whang (1987.

  8. 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...

  9. Bowel Endometriosis Syndrome

    DEFF Research Database (Denmark)

    Riiskjær, M; Egekvist, A G; Hartwell, D

    2017-01-01

    STUDY QUESTION: Is it possible to develop a validated score that can identify women with Bowel Endometriosis Syndrome (BENS) and be used to monitor the effect of medical and surgical treatment? SUMMARY ANSWER: The BENS score can be used to identify women with BENS and to monitor the effect...

  10. The Slow Learner.

    Science.gov (United States)

    Roucek, Joseph S., Ed.

    Papers on the slow learner treat physical defects and learning abilities, social and economic background as an obstacle to learning, the causes of dropouts and lapses in study, and the limitations and potential of the ungifted. The contribution interest in the slow learner has made to education is discussed; also discussed are problems of the…

  11. STUDY OF SLOW LEARNERS.

    Science.gov (United States)

    MIDANIK, J. SYDNEY

    A SPECIAL COMMITTEE REPORT TO THE BOARD OF EDUCATION, TORONTO, CANADA, REVIEWS THE PRESENT PROGRAM FOR SLOW LEARNERS (IQ 59 TO 90) AND RECOMMENDS A NEW TYPE OF EXPERIMENTAL HIGH SCHOOL. THE PROBLEM OF SLOW LEARNERS, THE USE AND MEANING OF INTELLIGENCE TESTS, AND THE DISTRIBUTION OF LEARNING CAPACITIES AMONG STUDENTS IN SCHOOL ARE DISCUSSED. THE…

  12. Experimental determination of the slow-neutron wavelength distribution

    DEFF Research Database (Denmark)

    Lebech, Bente; Mikke, K.; Sledziewska-Blocka, D.

    1970-01-01

    Different experiments for determining the slow-neutron wavelength distribution in the region 227-3 meV have been carried out, and the results compared. It is concluded that the slow-neutron wave-length distribution can be determined accurately by elastic scattering on a pure incoherent or a pure...

  13. Effects of Low-frequency Current Sacral Dermatome Stimulation on Idiopathic Slow Transit Constipation

    Science.gov (United States)

    Kim, Jin-Seop; Yi, Seung-Ju

    2014-01-01

    [Purpose] This study aimed to determine whether low-frequency current therapy can be used to reduce the symptoms of idiopathic slow transit constipation (ISTC). [Subjects] Fifteen patients (ten male and five female) with idiopathic slow transit constipation were enrolled in the present study. [Results] Bowel movements per day, bowel movements per week, and constipation assessment scale scores significantly improved after low-frequency current simulation of S2-S3. [Conclusion] Our results show that stimulation with low-frequency current of the sacral dermatomes may offer therapeutic benefits for a subject of patients with ISTC. PMID:25013277

  14. Transformer Industry Productivity Slows.

    Science.gov (United States)

    Otto, Phyllis Flohr

    1981-01-01

    Annual productivity increases averaged 2.4 percent during 1963-79, slowing since 1972 to 1.5 percent; computer-assisted design and product standardization aided growth in output per employee-hour. (Author)

  15. 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.

  16. Slow medical education.

    Science.gov (United States)

    Wear, Delese; Zarconi, Joseph; Kumagai, Arno; Cole-Kelly, Kathy

    2015-03-01

    Slow medical education borrows from other "slow" movements by offering a complementary orientation to medical education that emphasizes the value of slow and thoughtful reflection and interaction in medical education and clinical care. Such slow experiences, when systematically structured throughout the curriculum, offer ways for learners to engage in thoughtful reflection, dialogue, appreciation, and human understanding, with the hope that they will incorporate these practices throughout their lives as physicians. This Perspective offers several spaces in the medical curriculum where slowing down is possible: while reading and writing at various times in the curriculum and while providing clinical care, focusing particularly on conducting the physical exam and other dimensions of patient care. Time taken to slow down in these ways offers emerging physicians opportunities to more fully incorporate their experiences into a professional identity that embodies reflection, critical awareness, cultural humility, and empathy. The authors argue that these curricular spaces must be created in a very deliberate manner, even on busy ward services, throughout the education of physicians.

  17. Advances in small bowel transplantation

    OpenAIRE

    Gürkan, Alp

    2017-01-01

    Small bowel transplantation is a life-saving surgery for patients with intestinal failure. The biggest problem in intestinal transplantation is graft rejection. Graft rejection is the main reason for morbidity and mortality. Rejection has a negative effect on the survival of the graft. While 50%–75% of small bowel transplantation patients experience acute rejection, chronic rejection occurs in approximately 15% of patients. Immune monitoring is crucial after small bowel transplantation. Unlik...

  18. Kinetic slow mode-type solitons

    Directory of Open Access Journals (Sweden)

    K. Baumgärtel

    2005-01-01

    Full Text Available One-dimensional hybrid code simulations are presented, carried out in order both to study solitary waves of the slow mode branch in an isotropic, collisionless, medium-β plasma (βi=0.25 and to test the fluid based soliton interpretation of Cluster observed strong magnetic depressions (Stasiewicz et al., 2003; Stasiewicz, 2004 against kinetic theory. In the simulations, a variety of strongly oblique, large amplitude, solitons are seen, including solitons with Alfvenic polarization, similar to those predicted by the Hall-MHD theory, and robust, almost non-propagating, solitary structures of slow magnetosonic type with strong magnetic field depressions and perpendicular ion heating, which have no counterpart in fluid theory. The results support the soliton-based interpretation of the Cluster observations, but reveal substantial deficiencies of Hall-MHD theory in describing slow mode-type solitons in a plasma of moderate beta.

  19. 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

  20. 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

  1. Physiologic effects of bowel preparation

    DEFF Research Database (Denmark)

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

    2004-01-01

    PURPOSE: Despite the universal use of bowel preparation before colonoscopy and colorectal surgery, the physiologic effects have not been described in a standardized setting. This study was designed to investigate the physiologic effects of bowel preparation. METHODS: In a prospective study, 12...... healthy volunteers (median age, 63 years) underwent bowel preparation with bisacodyl and sodium phosphate. Fluid and food intake were standardized according to weight, providing adequate calorie and oral fluid intake. Before and after bowel preparation, weight, exercise capacity, orthostatic tolerance......, plasma and extracellular volume, balance function, and biochemical parameters were measured. RESULTS: Bowel preparation led to a significant decrease in exercise capacity (median, 9 percent) and weight (median, 1.2 kg). Plasma osmolality was significantly increased from 287 to 290 mmol kg(-1), as well...

  2. Physiologic effects of bowel preparation

    DEFF Research Database (Denmark)

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

    2004-01-01

    PURPOSE: Despite the universal use of bowel preparation before colonoscopy and colorectal surgery, the physiologic effects have not been described in a standardized setting. This study was designed to investigate the physiologic effects of bowel preparation. METHODS: In a prospective study, 12...... healthy volunteers (median age, 63 years) underwent bowel preparation with bisacodyl and sodium phosphate. Fluid and food intake were standardized according to weight, providing adequate calorie and oral fluid intake. Before and after bowel preparation, weight, exercise capacity, orthostatic tolerance...... preparation has significant adverse physiologic effects, which may be attributed to dehydration. The majority of these findings is small and may not be of clinical relevance in otherwise healthy patients undergoing bowel preparation and following recommendations for oral fluid intake....

  3. Slow Learners Speed Up

    Science.gov (United States)

    Becker, Leonard

    1975-01-01

    The article describes a work/study program for slow learners where the students spend a month at the Brooklyn Bureau's Department for the Handicapped, an agency where the physically and emotionally handicapped are given a comprehensive program of work training, job placement, homemaker training, and recreation. (Author/JB)

  4. SPS slow extraction septa

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    SPS long straight section (LSS) with a series of 5 septum tanks for slow extraction (view in the direction of the proton beam). There are 2 of these: in LSS2, towards the N-Area; in LSS6 towards the W-Area. See also Annual Report 1975, p.175.

  5. Slow moving neural source in the epileptic hippocampus can mimic progression of human seizures.

    Science.gov (United States)

    Chiang, Chia-Chu; Wei, Xile; Ananthakrishnan, Arvind Keshav; Shivacharan, Rajat S; Gonzalez-Reyes, Luis E; Zhang, Mingming; Durand, Dominique M

    2018-01-24

    Fast and slow neural waves have been observed to propagate in the human brain during seizures. Yet the nature of these waves is difficult to study in a surgical setting. Here, we report an observation of two different traveling waves propagating in the in-vitro epileptic hippocampus at speeds similar to those in the human brain. A fast traveling spike and a slow moving wave were recorded simultaneously with a genetically encoded voltage sensitive fluorescent protein (VSFP Butterfly 1.2) and a high speed camera. The results of this study indicate that the fast traveling spike is NMDA-sensitive but the slow moving wave is not. Image analysis and model simulation demonstrate that the slow moving wave is moving slowly, generating the fast traveling spike and is, therefore, a moving source of the epileptiform activity. This slow moving wave is associated with a propagating neural calcium wave detected with calcium dye (OGB-1) but is independent of NMDA receptors, not related to ATP release, and much faster than those previously recorded potassium waves. Computer modeling suggests that the slow moving wave can propagate by the ephaptic effect like epileptiform activity. These findings provide an alternative explanation for slow propagation seizure wavefronts associated with fast propagating spikes.

  6. 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.

  7. Two-wave propagation in in vitro swine distal ulna

    Science.gov (United States)

    Mano, Isao; Horii, Kaoru; Matsukawa, Mami; Otani, Takahiko

    2015-07-01

    Ultrasonic transmitted waves were obtained in an in vitro swine distal ulna specimen, which mimics a human distal radius, that consists of interconnected cortical bone and cancellous bone. The transmitted waveforms appeared similar to the fast waves, slow waves, and overlapping fast and slow waves measured in the specimen after removing the surface cortical bone (only cancellous bone). In addition, the circumferential waves in the cortical bone and water did not affect the fast and slow waves. This suggests that the fast-and-slow-wave phenomenon can be observed in an in vivo human distal radius.

  8. Accuracy of abdominal auscultation for bowel obstruction

    DEFF Research Database (Denmark)

    Breum, Birger Michael; Rud, Bo; Kirkegaard, Thomas

    2015-01-01

    AIM: To investigate the accuracy and inter-observer variation of bowel sound assessment in patients with clinically suspected bowel obstruction. METHODS: Bowel sounds were recorded in patients with suspected bowel obstruction using a Littmann(®) Electronic Stethoscope. The recordings were processed...

  9. Ageing with neurogenic bowel dysfunction

    DEFF Research Database (Denmark)

    Nielsen, S D; Faaborg, Pia Møller; Finnerup, Nanna Brix

    2017-01-01

    at 18% in 1996 and 19% in 2015. During the 19-year period, there had been no significant change in the methods for bowel care, but 22 (20%) had undergone surgery for bowel dysfunction, including 11 (10%) who had some form of stoma. Conclusion: Self-assessed severity of constipation increased but quality...... of life remained stable in a cohort of people with SCI followed prospectively for 19 years. Methods for bowel care remained surprisingly stable but a large proportion had undergone stoma surgery....

  10. Chemical wave in the un-illuminated aminophenol-bromate beads system

    Science.gov (United States)

    Harati, Mohammad

    2009-07-01

    We report observation of slow oscillations and slow waves in the aminophenol system. The system with slow oscillations in the stirred batch reactor does not always exhibit slow waves. The unperturbed system exhibits more than 2 days of wave activity, while the perturbed system shows about 5 days of wave activity. The longest lifetime of wave propagation stage and quiescent window were 30 and 11 h, respectively.

  11. 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...

  12. Bowel Control Problems (Fecal Incontinence)

    Science.gov (United States)

    ... System & How it Works Zollinger-Ellison Syndrome Bowel Control Problems (Fecal Incontinence) View or Print All Sections ... NIDDK would like to thank: William E. Whitehead, Ph.D., University of North Carolina School of Medicine ...

  13. IRRITATED BOWEL SYNDROME IN CHILDREN

    Directory of Open Access Journals (Sweden)

    V. F. Privorotskiy

    2012-01-01

    Full Text Available Irritated bowel syndrome is a significant and underestimated problem in childhood. This condition is not so good studied in pediatrics in comparison with adult practice. Pediatricians often diagnosed this disease in infants and young children without proper reasons. The authors analyze current opinions about etiology and pathogenesis, clinical presentation, diagnosticsand treatment of irritated bowel syndrome in children. An emphasis is made on diagnostic criteria, which allow suggesting and confirming the diagnosis.

  14. Theoretical and experimental study of structural slow light in a microfiber coil resonator.

    Science.gov (United States)

    Ma, Cheng-Ju; Ren, Li-Yong; Xu, Yi-Ping; Wang, Ying-Li; Zhou, Hong; Fu, Hai-Wei; Wen, Jin

    2015-06-20

    In this paper, a compact slow-light microfiber coil resonator (MCR) is fabricated and the slow-light properties of it are analyzed and tested. Based on coupled-wave theory, a theoretical model for describing the slow-light propagation in the MCR is established. Experimentally, the MCR slow-light element is fabricated and its relative slow-light time delay is measured. The group velocity of the light pulse in the MCR slow-light element can be reduced to about 0.47c (c is the speed of light in vacuum) and the shape of the light pulse passing through the MCR is well preserved.

  15. 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.

  16. Mebeverine alters small bowel motility in irritable bowel syndrome.

    Science.gov (United States)

    Evans, P R; Bak, Y T; Kellow, J E

    1996-10-01

    Despite its widespread use in irritable bowel syndrome (IBS), limited clinical data exist on the effects of mebeverine hydrochloride on gastrointestinal motility. Human motor activity in the small bowel is more reproducible than that in the large bowel; therefore the aim of this study was to determine in the small bowel the effects of oral mebeverine in both IBS patients and in healthy controls. Twelve IBS patients (11 females/1 male, 46 +/- 13 years old)-predominant constipation (IBS-C, n = 6) and predominant diarrhoea (IBS-D, n = 6)-and six healthy controls, underwent continuous 48 h ambulant recording of small bowel motor activity. One low energy (400 kcal) and one high energy (800 kcal) standard meal were administered in each consecutive 24-h period. Subjects received, in blinded fashion, placebo tablets in the first 24 h then mebeverine 135 mg q.d.s. in the second 24 h. Mebeverine had no effect on parameters of small bowel motility in controls. In contrast, in both IBS-C (P = 0.01) and IBS-D (P mebeverine administration. Also, after mebeverine the proportion of the migrating motor complex cycle occupied by phase 2 was reduced in IBS-D (P = 0.01), while phase 2 burst frequency was reduced in IBS-C (P mebeverine, in the initial dosing period, has a normalizing effect in the small bowel in IBS, enhancing contractile activity in a similar fashion to 'prokinetic' agents, as well as producing alterations in motor activity consistent with an 'antispasmodic' effect.

  17. Slow-light solitons revisited

    OpenAIRE

    Rybin, A. V.; Vadeiko, I. P.; Bishop, A. R.

    2006-01-01

    We investigate propagation of slow-light solitons in atomic media described by the nonlinear $\\Lambda$-model. Under a physical assumption, appropriate to the slow light propagation, we reduce the $\\Lambda$-scheme to a simplified nonlinear model, which is also relevant to 2D dilatonic gravity. Exact solutions describing various regimes of stopping slow-light solitons can then be readily derived.

  18. Irritable bowel syndrome: Is it "irritable brain" or "irritable bowel"?

    Directory of Open Access Journals (Sweden)

    Susanta Kumar Padhy

    2015-01-01

    Full Text Available Irritable bowel syndrome (IBS has been recognized as one of the most common and best studied disorders among the group of functional gastrointestinal disorders. It is a functional bowel disorder in which abdominal pain or discomfort is associated with defecation or a change in bowel habit. In the Western world, IBS appears to affect up to 20% of the population at any given time but in Asian countries, the median value of IBS prevalence defined by various criteria ranges between 6.5% and 10.1%, and community prevalence of 4% is found in North India. Those attending gastroenterology clinics represent only the tip of the iceberg. The disorder substantially impairs the quality of life, and the overall health-care costs are high. IBS has therefore gained increased attention from clinicians, researchers, and pharmaceutical industries. It is often frustrating to both patients and physicians as the disease is usually chronic in nature and difficult to treat. However, the understanding of IBS has been changing from time to time and still most of its concepts are unknown. In this review we have discussed, debated, and synthesized the evidence base, focusing on underlying mechanisms in the brain and bowel. We conclude that it is both brain and bowel mechanisms that are responsible. The clinical implication of such mechanisms is discussed.

  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. 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.

  1. Atom slowing via dispersive optical interactions

    Science.gov (United States)

    Hamamda, M.; Boustimi, M.; Correia, F.; Baudon, J.; Taillandier-Loize, T.; Dutier, G.; Perales, F.; Ducloy, M.

    2012-02-01

    A promising technique of atom slowing is proposed. It is based upon the dispersive interaction of atoms with optical potential pulses generated by a far-off-resonance standing wave modulated in time. Each pulse reduces the velocity by a small amount. By repeating the process thousands of times, the velocity can be lowered from several hundreds of meters per second down to almost zero, over a path as short as 20cm. In the absence of any random recoil process, the initial characteristics of the beam are preserved.

  2. 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.

  3. Primary small bowel anastomosis in generalised peritonitis

    NARCIS (Netherlands)

    deGraaf, JS; van Goor, Harry; Bleichrodt, RP

    Objective: To find out if primary small bowel anastomosis of the bowel is safe in patients with generalised peritonitis who are treated by planned relaparotomies. Design: Retrospective study. Setting: University hospital, The Netherlands. Subjects. 10 Patients with generalised purulent peritonitis

  4. Inflammatory Bowel Disease (IBD) and Pregnancy

    Science.gov (United States)

    Inflammatory Bowel Disease In every pregnancy, a woman starts out with a 3-5% chance of having a baby ... risk. This sheet talks about whether exposure to inflammatory bowel disease may increase the risk for birth defects over ...

  5. Laparoscopic Bowel Injuries Among Gynecologic Patients

    Directory of Open Access Journals (Sweden)

    Francisco A. R. Garcia

    1997-01-01

    Full Text Available Bowel injury is an uncommon but recognized risk of operative laparoscopy. Because of the significant morbidity that can occur with this complication, it is important that clinicians be aware of its incidence, presentation, and management. This manuscript outlines the common causes of bowel injury, including herniation and traumatic bowel perforation. Management of laparoscopic bowel injuries is discussed and recommendations are made for avoidance of such complications.

  6. Inflammatory bowel disease and pregnancy.

    Science.gov (United States)

    Maliszewska, Anna Małgorzata; Warska, Aleksandra; Cendrowski, Krzysztof; Sawicki, Włodzimierz

    2017-01-01

    Inflammatory bowel disease (IBD) comprising Crohn's disease (CD), ulcerative colitis (UC), and IBD-unclassified (IBD-U) may appear at any age. As such, IBD commonly affects young patients in their reproductive age. Rate of voluntary childlessness among women with IBD far exceed that of the general population, as patients with IBD fear not only the effect of pregnancy on the course of inflammatory bowel disease, but also the increased risk of the offspring developing the disease, adverse pregnancy outcomes, the effect IBD treatment may have on the health and development of the infant or the risk of relapse during pregnancy and the influence of lactation on child development and disease course. This article aims at improving pre-conception counseling of patients with inflammatory bowel disease.

  7. Irritable bowel syndrome in primary care

    NARCIS (Netherlands)

    Bijkerk, C.J.

    2008-01-01

    Irritable bowel syndrome (IBS) is a functional bowel disorder in which abdominal pain or discomfort is associated with a change in bowel habit, or with features of disordered defecation. Patients and doctors in primary care generally agree on IBS symptomatology and consider pain and bloating as its

  8. Perforated small bowel in omphalocele at birth

    Directory of Open Access Journals (Sweden)

    Kale R

    2006-01-01

    Full Text Available The rupture of an omphalocele sac during birth is a well recognized entity. The associated lesions due to vascular compromise can result in necrosis of the bowel with perforation. Spontaneous bowel perforation in an omphalocele at birth is not reported in the literature. We describe a case with bowel perforation at the fundus of an omphalocele in a newborn.

  9. Gravity slows light

    Science.gov (United States)

    O'Sullivan, Ian

    2014-03-01

    The speed of light is measured as a constant number of metres per second. However, a meter is a measure of how far light travels in a second. That is, light always travels as far as it does in a second every second. This is a circular definition. When measured against other things, light speed must change. Gravity is usually described as a consequence of a curve in spacetime. The word ``space'' has two distinct meanings. In geometry, space is a continuous area. In relativity, ``space'' refers exclusively to geometric spaces measured with light. ``Time'' in a relativistic sense also refers exclusively to the passage of time as measured against light. So a curve in spacetime (a relativistic concept) is a gradual deviation in the thing we use to measure geometric spaces and the passage of time, i.e. the speed of light. I show how Newtonian gravity can explain observable phenomena if the speed of light is inversely proportional to the strength of the gravitational field. For example, we would also expect light to refract as it changes speed passing near massive bodies. Boundary conditions are also discussed, for example, very high gravity will slow light to a stop, making it impossible to measure anything against light, giving a gravitational singularity.

  10. Reflected-wave maser. [low noise amplifier

    Science.gov (United States)

    Clauss, R. C. (Inventor)

    1976-01-01

    A number of traveling-wave, slow-wave maser structures, containing active maser material but absent the typical ferrite isolators, are immersed in a nonuniform magnetic field. The microwave signal to be amplified is inserted at a circulator which directs the signal to a slow-wave structure. The signal travels through the slow-wave structure, being amplified according to the distance traveled. The end of the slow-wave structure farthest from the circulator is arranged to be a point of maximum reflection of the signal traveling through the slow-wave structure. As a consequence, the signal to be amplified traverses the slow-wave structure again, in the opposite direction (towards the circulator) experiencing amplification equivalent to that achieved by a conventional traveling-wave maser having twice the length. The circulator directs the amplified signal to following like stages of amplification. Isolators are used in between stages to prevent signals from traveling in the wrong direction, between the stages. Reduced signal loss is experienced at each stage. The high gain produced by each slow-wave structure is reduced to a moderate value by use of a nonuniform magnetic field which also broadens the line width of the maser material. The resulting bandwidth can be exceptionally wide. Cascaded stages provide high gain, exceptionally wide bandwith and very low noise temperature.

  11. 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.

  12. Do slow shocks precede some coronal mass ejections

    Energy Technology Data Exchange (ETDEWEB)

    Hundhausen, A.J.; Holzer, T.E.; Low, B.C.

    1987-10-01

    The observed speeds of coronal mass ejections are often below the estimated Alfven speed but above the sound speed for the background solar corona. This suggets that slow magnetohydrodynamic shocks may form as mass ejections sweep through the corona. We argue on the basis of the Rankine-Hugoniot relations and the propagation of small-amplitude slow mode waves that the shape of a slow shock front would be flattened (with respect to a sun-centered sphere) or perhaps even concave outward (from the sun) and thus present a very different appearance from the fast coronal shock waves that have been commonly modeled as wrapping around a mass ejection. The region behind a slow shock front standing just off the top of a coronal mass ejection would extend well out beyond the visible flanks of the ejection. The deflections of coronal structures that are commonly observed well outside of these flanks (and which are inconsistent with a fast shock wrapped around the mass ejection) are consistent with the presence of the slow shock, whether they lie in the enlarged postshock region or in a region still further beyond. Although the flattering of the tops of some mass ejections suggests our proposed slow shock configuration, a true test of its existence awaits formulation of quantitative models and detailed comparison with observations. copyright American Geophysical Union 1987

  13. Memory improvement via slow-oscillatory stimulation during sleep in older adults.

    Science.gov (United States)

    Westerberg, Carmen E; Florczak, Susan M; Weintraub, Sandra; Mesulam, M-Marsel; Marshall, Lisa; Zee, Phyllis C; Paller, Ken A

    2015-09-01

    We examined the intriguing but controversial idea that disrupted sleep-dependent consolidation contributes to age-related memory decline. Slow-wave activity during sleep may help strengthen neural connections and provide memories with long-term stability, in which case decreased slow-wave activity in older adults could contribute to their weaker memories. One prediction from this account is that age-related memory deficits should be reduced by artificially enhancing slow-wave activity. In young adults, applying transcranial current oscillating at a slow frequency (0.75 Hz) during sleep improves memory. Here, we tested whether this procedure can improve memory in older adults. In 2 sessions separated by 1 week, we applied either slow-oscillatory stimulation or sham stimulation during an afternoon nap in a double-blind, crossover design. Memory tests were administered before and after sleep. A larger improvement in word-pair recall and higher slow-wave activity was observed with slow-oscillatory stimulation than with sham stimulation. This is the first demonstration that this procedure can improve memory in older adults, suggesting that declarative memory performance in older adults is partly dependent on slow-wave activity during sleep. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Cutaneous Manifestations in Inflammatory Bowel Diseases

    Directory of Open Access Journals (Sweden)

    Simona Roxana Georgescu

    2015-10-01

    Full Text Available Inflammatory bowel diseases have a high frequency in Europe. They are chronic disorders that evolve with relapses and remissions. Clinical features include the signs of underlying inflammatory bowel disease and also signs of extraintestinal manifestations. Cutaneous disorders are the most common extraintestinal manifestations associated with inflammatory bowel diseases, which can be dependent on or independent of gastrointestinal disease activity. The main cutaneous disorders are erythema nodosum and pyodermagangrenosum. The pathogenic mechanisms are not fully understood but it seems that related mechanisms are involved in the development of inflammatory bowel diseases and extraintestinal manifestations. Treatment should be aimed at both the cutaneous manifestations and the bowel inflammation

  15. Coaxial slow source

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, R.D.; Jarboe, T.R.

    1990-01-01

    Field reversed configurations (FRCs) are a class of compact toroid with not toroidal field. The field reversed theta pinch technique has been successfully used for formation of FRCs since their inception in 1958. In this method an initial bias field is produced. After ionization of the fill gas, the current in the coil is rapidly reversed producing the radial implosion of a current sheath. At the ends of the coil the reversed field lines rapidly tear and reconnect with the bias field lines until no more bias flux remains. At this point, vacuum reversed field accumulates around the configuration which contracts axially until an equilibrium is reached. When extrapolating the use of such a technique to reactor size plasmas two main shortcomings are found. First, the initial bias field, and hence flux in a given device, which can be reconnected to form the configuration is limited from above by destructive axial dynamics. Second, the voltages required to produce rapid current reversal in the coil are very large. Clearly, a low voltage formation technique without limitations on flux addition is desirable. The Coaxial Slow Source (CSS) device was designed to meet this need. It has two coaxial theta pinch coils. Coaxial coil geometry allows for the addition of as much magnetic flux to the annular plasma between them as can be generated inside the inner coil. Furthermore the device can be operated at charging voltages less than 10 kV and on resistive diffusion, rather than implosive time scales. The inner coil is a novel, concentric, helical design so as to allow it to be cantilevered on one end to permit translation of the plasma. Following translation off the inner coil the Annular Field Reversed Configuration would be re-formed as a true FRC. In this paper we investigate the formation process in the new parallel configuration., CSSP, in which the inner and outer coils are connected in parallel to the main capacitor bank.

  16. Coaxial slow source

    Science.gov (United States)

    Brooks, R. D.; Jarboe, T. R.

    Field reversed configurations (FRC's) are a class of compact toroid with no toroidal field. The field reversed theta pinch technique has been successfully used for formation of FRC's since their inception in 1958. In this method an initial bias field is produced. After ionization of the fill gas, the current in the coil is rapidly reversed producing the radial implosion of a current sheath. At the ends of the coil the reversed field lines rapidly tear and reconnect with the bias field lines until no more bias flux remains. At this point, vacuum reversed field accumulates around the configuration which contracts axially until an equilibrium is reached. When extrapolating the use of such a technique to reactor size plasmas two main shortcomings are found. First, the initial bias field, and hence flux in a given device, which can be reconnected to form the configuration is limited from above by destructive axial dynamics. Second, the voltages required to produce rapid current reversal in the coil are very large. Clearly, a low voltage formation technique without limitations on flux addition is desirable. The Coaxial Slow Source (CSS) device was designed to meet this need. It has two coaxial theta pinch coils. Coaxial coil geometry allows for the addition of as much magnetic flux to the annular plasma between them as can be generated inside the inner coil. Furthermore the device can be operated at charging voltages less than 10 kV and on resistive diffusion, rather than implosive time scales. The inner coil is a novel, concentric, helical design so as to allow it to be cantilevered on one end to permit translation of the plasma. Following translation off the inner coil the Annular Field Reversed Configuration would be re-formed as a true FRC. In this paper, we investigate the formation process in the new parallel configuration, CSSP, in which the inner and outer coils are connected in parallel to the main capacitor bank.

  17. 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.

  18. Capsule endoscopy: Beyond small bowel

    Directory of Open Access Journals (Sweden)

    Samuel N Adler

    2012-01-01

    Full Text Available In this article the brief and dramatic history of capsule endoscopy of the digestive tract is reviewed. Capsule endoscopy offers a non invasive method to diagnose diseases that affect the esophagus, small bowel and colon. Technological improvements relating to optics, software, data recorders with two way communication have revolutionized this field. These advancements have produced better diagnostic performance.

  19. Small Bowel Review: Part II

    Directory of Open Access Journals (Sweden)

    ABR Thomson

    1999-01-01

    Full Text Available In the past year there have been many advances in the area of small bowel physiology and pathology. In preparation for this review, over 500 papers were assessed; some have been selected and reviewed, with a particular focus on presenting clinically useful information for the practising gastroenterologist.

  20. Radiological Evaluation of Bowel Ischemia

    Science.gov (United States)

    Dhatt, Harpreet S.; Behr, Spencer C; Miracle, Aaron; Wang, Zhen Jane; Yeh, Benjamin M.

    2015-01-01

    Intestinal ischemia, which refers to insufficient blood flow to the bowel, is a potentially catastrophic entity that may require emergent intervention or surgery in the acute setting. Although the clinical signs and symptoms of intestinal ischemia are nonspecific, CT findings can be highly suggestive in the correct clinical setting. In this chapter we review the CT diagnosis of arterial, venous, and non-occlusive intestinal ischemia. We discuss the vascular anatomy, pathophysiology of intestinal ischemia, CT techniques for optimal imaging, key and ancillary radiological findings, and differential diagnosis. In the setting of an acute abdomen, rapid evaluation is necessary to identify intraabdominal processes that require emergent surgical intervention (1). While a wide-range of intraabdominal diseases may be present from trauma to inflammation, one of the most feared disorders is mesenteric ischemia, also known as intestinal ischemia, which refers to insufficient blood flow to the bowel (2). Initial imaging evaluation for intestinal ischemia is typically obtained with CT. Close attention to technique and search for key radiologic features with relation to the CT technique is required. Accurate diagnosis depends on understanding the vascular anatomy, epidemiology, and pathophysiology of various forms of mesenteric ischemia and their corresponding radiological findings on MDCT. At imaging, not only is inspection of the bowel itself important, but evaluation of the mesenteric fat, vasculature, and surrounding peritoneal cavity also helps improves accuracy in the diagnosis of bowel ischemia. PMID:26526436

  1. Integrating Slow Learners in Wales.

    Science.gov (United States)

    Lowden, Gordon

    1984-01-01

    Results of interviews, attitude scales, questionnaires, and school record reviews revealed that teachers (N=120) generally approved of the principle of integration of slow learners while viewing the practice as impractical and sometimes undesirable. Students were not particularly antagonistic to slow learners, and parents were generally satisfied…

  2. Bowel resection in Nigerian children

    Directory of Open Access Journals (Sweden)

    Abdur-Rahman L

    2009-01-01

    Full Text Available Background : Although bowel resections are commonly done for congenital malformations in children in developed countries, they usually follow neglected and preventable acquired diseases of the intestine in developing countries. Objectives : To determine the indications and outcome of bowel resections in children of a developing country in a university teaching hospital. Materials and Methods: Data of the patients operated (from birth to 15 years was retrospectively collected over eight years (January 1999 to December 2006. The biodata of children included the following: Indications for operation, type of operations, duration of admission, and outcome of treatment including complications. Patients with Hirschsprung′s disease were excluded from the study because bowel resection forms part of their definitive surgical management. Results : There were 70 patients (38 boys and 32 girls. The age ranged between four hours to 15 years (median, five months. There were 16 (22.9% neonates, 26 (37.1% infants, and 28 (40% grown children. The indications were congenital anomalies in the 16 neonates. Also, 23 (88.5% infants had intussusception, 2 (7.7% had midgut vovulusm and 1 (3.8% had congenital small intestine band. Among the grown children, typhoid ileal perforation (TIP was seen in 14 (50.0%, intussusception in 5 (17.9%, and other causes in nine patients. Overall, intussusception was the most common indication for bowel resection, followed by TIP. A total of 24 patients developed 33 complications. Complications included wound infection in 47.8% and anastomotic leak in 42.8%. The duration of admission ranged between 4-35 days (median, 15 days. The overall mortality was 17.1% -; which was highest among neonates (56.3%, followed by the infants (26.9% -. Conclusion : Bowel resections are mainly done for intussusception and complications of TIP at our centre. Late presentation, preexisting malnutrition, and nonavailability of parenteral nutrition

  3. 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.

  4. Modulation of sleep quality and autonomic functioning by symptoms of depression in women with irritable bowel syndrome.

    Science.gov (United States)

    Robert, Jennifer J T; Orr, William C; Elsenbruch, Sigrid

    2004-08-01

    The objective of this study was to determine how depressive symptoms affect autonomic activity during sleep, objective and subjective sleep, and gastrointestinal symptom severity in women with irritable bowel syndrome (IBS). Seventy women who met the Rome II criteria for IBS and 21 healthy volunteers participated. All participants were recruited from the surrounding community. IBS patients were stratified into two groups based on their Beck Depression Inventory II score and 44 IBS patients with depressive symptoms (IBS+DS) were compared to 26 IBS patients without depressive symptoms (IBS-DS). Autonomic activity was measured by heart rate variability (HRV) analysis. Fifteen-minute segments were selected from a baseline presleep period, stage 2, slow-wave sleep, and rapid-eye movement sleep for heart rate variability spectral analysis. Subjective sleep quality was assessed by the Pittsburg Sleep Quality Index (PSQI) and gastrointestinal symptom severity was assessed by an 18-item questionnaire. The IBS+DS group reported significantly (P sleep complaints, measured by the PSQI, than the IBS-DS group and healthy controls. The IBS+DS group took significantly (P activity during the baseline presleep period or sleep stages. The results demonstrated that IBS patients with significant depressive symptoms had increased gastrointestinal symptom severity, increased sleep complaints, and alterations in sleep architecture compared to healthy controls and IBS patients without significant depressive symptoms.

  5. What do patients with irritable bowel syndrome dream about? A comparison with inflammatory bowel disease.

    Science.gov (United States)

    Lal, S; Whorwell, P J

    2002-07-01

    It is a common experience for people to dream of events about which they are either anxious or concerned. We therefore hypothesised that the dreams of patients with irritable bowel syndrome may reflect their worries about their problem especially as hospital out-patients with this disorder tend to exhibit some anxiety. In addition, dreaming about, for instance bowels, in patients with irritable bowel syndrome in excess of that observed in other gastrointestinal disorders may be of importance. To establish whether patients with irritable bowel syndrome dream about bowel-related issues more than controls or patients with inflammatory bowel disease. A total of 57 patients with irritable bowel syndrome and 57 patients with inflammatory bowel disease were compared with 60 healthy controls. All subjects completed a structured questionnaire concerning sleeping habits and dream characteristics as well as an assessment of anxiety and depression. There were no differences in the sleeping habits between any of the groups. However, significantly more patients with irritable bowel syndrome and inflammatory bowel disease dreamt about their bowels (22% inflammatory bowel disease patients, 18% irritable bowel syndrome patients vs 3% of controls, p disorders, of both a functional and organic nature, may influence the nature of dreams. In those patients who dream about their symptoms, it would be interesting to know whether this affects the course of their disease, either positively or negatively, in any way.

  6. Nutrition in inflammatory bowel disease.

    Science.gov (United States)

    Stein, R B; Lichtenstein, G R; Rombeau, J L

    1999-09-01

    Clinical and basic research continues to expand our understanding of the complex pathogenesis of inflammatory bowel diseases. The potential roles played by fatty acid intake, serum leptin, and nitric oxide in the promotion of intestinal inflammation in Crohn's disease and ulcerative colitis will be reviewed. In addition, important advances in the areas of bone disease, vitamin deficiency, growth failure, and home parenteral nutrition will be discussed.

  7. Inflammatory Bowel Disease in Primary Immunodeficiencies.

    Science.gov (United States)

    Kelsen, Judith R; Sullivan, Kathleen E

    2017-08-01

    Inflammatory bowel disease is most often a polygenic disorder with contributions from the intestinal microbiome, defects in barrier function, and dysregulated host responses to microbial stimulation. There is, however, increasing recognition of single gene defects that underlie a subset of patients with inflammatory bowel disease, particularly those with early-onset disease, and this review focuses on the primary immunodeficiencies associated with early-onset inflammatory bowel disease. The advent of next-generation sequencing has led to an improved recognition of single gene defects underlying some cases of inflammatory bowel disease. Among single gene defects, immune response genes are the most frequent category identified. This is also true of common genetic variants associated with inflammatory bowel disease, supporting a pivotal role for host responses in the pathogenesis. This review focuses on practical aspects related to diagnosis and management of children with inflammatory bowel disease who have underlying primary immunodeficiencies.

  8. Neurostimulation for Neurogenic Bowel Dysfunction

    Directory of Open Access Journals (Sweden)

    J. Worsøe

    2013-01-01

    Full Text Available Background. Loss of normal bowel function caused by nerve injury, neurological disease or congenital defects of the nervous system is termed neurogenic bowel dysfunction (NBD. It usually includes combinations of fecal incontinence, constipation, abdominal pain and bloating. When standard treatment of NBD fails surgical procedures are often needed. Neurostimulation has also been investigated, but no consensus exists about efficacy or clinical use. Methods. A systematic literature search of NBD treated by sacral anterior root stimulation (SARS, sacral nerve stimulation (SNS, peripheral nerve stimulation, magnetic stimulation, and nerve re-routing was made in Pubmed, Embase, Scopus, and the Cochrane Library. Results. SARS improves bowel function in some patients with complete spinal cord injury (SCI. Nerve re-routing is claimed to facilitate defecation through mechanical stimulation of dermatomes in patients with complete or incomplete SCI or myelomeningocele. SNS can reduce NBD in selected patients with a variety of incomplete neurological lesions. Peripheral stimulation using electrical stimulation or magnetic stimulation may represent non-invasive alternatives. Conclusion. Numerous methods of neurostimulation to treat NBD have been investigated in pilot studies or retrospective studies. Therefore, larger controlled trials with well-defined inclusion criteria and endpoints are recommended before widespread clinical use of neurostimulation against NBD.

  9. Optical signal processing using slow and fast light technologies

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...... 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...

  10. Transabdominal Ultrasonography of the Small Bowel

    OpenAIRE

    Rudolf Kralik; Peter Trnovsky; Marcela Kopáčová

    2013-01-01

    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 dop...

  11. Spatial Damping of Linear Compressional Magnetoacoustic Waves ...

    Indian Academy of Sciences (India)

    shows greater wave damping at low values of radiative time and then attains some maximum value and then decreases. The slow mode wave has higher values of damping per wavelength, showing higher levels of damping due to radiation. For τR → ∞, the wave takes infinite time to damp and therefore travels very long ...

  12. Non-small-bowel abnormalities identified during small bowel capsule endoscopy

    NARCIS (Netherlands)

    Hoedemakers, Reinier; Westerhof, Jessie; Weersma, Rinse K.; Koornstra, Jan J.

    2014-01-01

    AIM: To investigate the incidence of non-small-bowel abnormalities in patients referred for small bowel capsule endoscopy, this single center study was performed. METHODS: Small bowel capsule endoscopy is an accepted technique to investigate obscure gastrointestinal bleeding. This is defined as

  13. Definition and Facts for Irritable Bowel Syndrome

    Science.gov (United States)

    ... For Health Professionals Diabetes Discoveries & Practice Blog Health Communication Programs FAQs ... Syndrome (IBS) Definition & Facts Related Topics Section Navigation Irritable Bowel Syndrome ( ...

  14. Theory of carrier depletion and light amplification in active slow light photonic crystal waveguides.

    Science.gov (United States)

    Chen, Yaohui; Mørk, Jesper

    2013-12-02

    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 power.

  15. 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

    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......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...

  16. Nonlinear theory of slow light.

    Science.gov (United States)

    Rybin, Andrei; Timonen, Jussi

    2011-03-28

    In the framework of the nonlinear Λ model, propagation of solitons was analysed in atomic vapours and Bose-Einstein condensates. The complicated nonlinear interplay between fast and slow-light solitons in a Λ-type medium was shown to facilitate control of its optical transparency and formation of optical gates. An exact analytical description was given for the deceleration, stopping and revival of slow-light solitons in the experimentally relevant non-adiabatic regime. A stopping slow-light soliton imprints a localized immobile polarization pattern in the medium, which, as explicitly demonstrated here, can be used as a bit of readable optical memory. The whole process can be controlled with the background field and an auxiliary laser field. The latter regulates the signal velocity, while the slow-light soliton can be stopped by switching off the former. The location and shape of the imprinted memory bit were also determined. With few assumptions characteristic of slow light, the Λ model was reduced to a simpler nonlinear model that also describes two-dimensional dilatonic gravity. Exact solutions could now be derived also in the presence of relaxation. Spontaneous decay of the upper atomic level was found to be strongly suppressed, and the spatial form of the decelerating slow-light soliton was preserved, even if the optical relaxation time was much shorter than the typical time scale of the soliton. The effective relaxation coefficient of the slow-light soliton was significantly smaller than that of an arbitrary optical pulse. Such features are obviously of great importance when this kind of system is applied, in practice, to information processing. A number of experimentally observable properties of the solutions reported were found to be in good agreement with recent experimental results, and a few suggestions are also made for future experiments.

  17. 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.

  18. Synaptic Mechanisms of Memory Consolidation during Sleep Slow Oscillations.

    Science.gov (United States)

    Wei, Yina; Krishnan, Giri P; Bazhenov, Maxim

    2016-04-13

    Sleep is critical for regulation of synaptic efficacy, memories, and learning. However, the underlying mechanisms of how sleep rhythms contribute to consolidating memories acquired during wakefulness remain unclear. Here we studied the role of slow oscillations, 0.2-1 Hz rhythmic transitions between Up and Down states during stage 3/4 sleep, on dynamics of synaptic connectivity in the thalamocortical network model implementing spike-timing-dependent synaptic plasticity. We found that the spatiotemporal pattern of Up-state propagation determines the changes of synaptic strengths between neurons. Furthermore, an external input, mimicking hippocampal ripples, delivered to the cortical network results in input-specific changes of synaptic weights, which persisted after stimulation was removed. These synaptic changes promoted replay of specific firing sequences of the cortical neurons. Our study proposes a neuronal mechanism on how an interaction between hippocampal input, such as mediated by sharp wave-ripple events, cortical slow oscillations, and synaptic plasticity, may lead to consolidation of memories through preferential replay of cortical cell spike sequences during slow-wave sleep. Sleep is critical for memory and learning. Replay during sleep of temporally ordered spike sequences related to a recent experience was proposed to be a neuronal substrate of memory consolidation. However, specific mechanisms of replay or how spike sequence replay leads to synaptic changes that underlie memory consolidation are still poorly understood. Here we used a detailed computational model of the thalamocortical system to report that interaction between slow cortical oscillations and synaptic plasticity during deep sleep can underlie mapping hippocampal memory traces to persistent cortical representation. This study provided, for the first time, a mechanistic explanation of how slow-wave sleep may promote consolidation of recent memory events. Copyright © 2016 the authors 0270-6474/16/364231-17$15.00/0.

  19. 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.

  20. Irritable Bowel Syndrome and Complementary Health Practices

    Science.gov (United States)

    ... approaches for the treatment of irritable bowel syndrome. Nutrition in Clinical Practice. 2008;23(3):284–292. Wu JC. Complementary and alternative medicine modalities for the treatment of irritable bowel syndrome: facts or myths? Gastroenterology & Hepatology. 2010;6(11):705–711. Yoon ...

  1. 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....

  2. Surgical perspectives on inflammatory bowel disease

    African Journals Online (AJOL)

    VikasC

    J. Inflammatory bowel disease in Towsend: Sabiston. Textbook of Surgery. ... 1998; 44:28991. 19. Xie J, Itzkowitz SH. Cancer in inflammatory bowel disease. World J Gastroenterol 2008;14:37889. 20. Roses RE, Rombeau JL. Recent trends in the surgical ... dyselectrolytemia, anemia, and malnutrition are commonly present.

  3. Childhood Inflammatory Bowel Disease in Libya: Epidemiological ...

    African Journals Online (AJOL)

    Background & Aims: Inflammatory bowel disease is thought to be rare in Libya. The aim is to determine the prevalence of juvenile onset inflammatory bowel disease in Libya. Setting: Al-Fateh childrens' hospital, Benghazi, Libya. Methods: This is a retrospective study of all cases diagnosed over 10 years (1997-2006) with ...

  4. Bowel injury as a complication of laparoscopy

    NARCIS (Netherlands)

    van der Voort, M.; Heijnsdijk, E. A. M.; Gouma, D. J.

    2004-01-01

    Background: Bowel injury is a rare but serious complication of laparoscopic surgery. This review examines the incidence, location, time of diagnosis, causative instruments, management and mortality of laparoscopy-induced bowel injury. Methods: The review was carried out using the MeSH browser within

  5. Heritability in inflammatory bowel disease

    DEFF Research Database (Denmark)

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

    2015-01-01

    estimation regard genetic and environmental variance as separate entities, although it is now understood that there is a complex multidirectional interplay between genetic are environmental factors mediated by the microbiota, the epigenome, and the innate and acquired immune systems. Due to the limitations...... of heritability estimates, it is unlikely that a true value for heritability will be reached. Further work aimed at quantifying the variance explained across GWAS, epigenome-wide, and microbiota-wide association studies will help to define factors leading to inflammatory bowel disease....

  6. [Pregnancy and inflammatory bowel disease].

    Science.gov (United States)

    Walldorf, J; Zwirnmann, K; Seufferlein, T

    2011-01-01

    Medical advice regarding the desire to have children and pregnancy in patients with inflammatory bowel disease (IBD) is often requested. The influence of IBD on pregnancy and--vice versa--of pregnancy on the activity of IBD is discussed. Based on three clinical cases the chances and limitations of medical treatment of CED during pregnancy are reviewed. Generally it is important to balance the therapy between the patients desire to be treated most effectively and to deliver a healthy child after an uncomplicated pregnancy. An interdisciplinary treatment is always advisable in patients with IBD and a desire to have children.

  7. [Inflammatory bowel disease and pregnancy].

    Science.gov (United States)

    Parfenov, A I

    2012-01-01

    Inflammatory bowel disease (IBD) in pregnant women in their characteristics do not differ from general population, unless they had operations on the pelvic organs. Women with a first pregnancy, regardless of the activity of IBD have an increased risk of adverse pregnancy and high risk births. Most treatment methods are compatible with pregnancy and breastfeeding. Women affected by IBD should discuss their plans for pregnancy with the doctor first in order to know the possible dangers. Every patient in the IBD during pregnancy must be observed by a gastroenterologist, accoucheur and pediatrician to ensure peace of mother and child.

  8. 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.

  9. 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 embedde...... in a photonic crystal waveguide by FDTD Maxwell-Bloch simulations. The total group index scales linearly with the material based group index whicle the transmission has a power dependency on the material based absorption coefficient....

  10. Standing Slow MHD Waves in Radiatively Cooling Coronal Loops ...

    Indian Academy of Sciences (India)

    the individual and combined effects of radiation and thermal conduction are studied by displaying the analytical solution numerically. Our discussions and conclusions are presented in Section 5. 2. The model and governing equations. We model a straight coronal loop, in which the magnetic field is uniform and in.

  11. Optical Slow-Wave Metamaterials and Their Tunability/Applications

    Science.gov (United States)

    2012-05-01

    last month in Nano Letters (with an impact factor over 12). In this project we have also proposed a plasmonic super absorber. This structure is... Impact Factor : 12.219) 2) Y. Cui, J. Xu, K. H. Fung, Y. Jin, A. Kumar, S. He, and N. X. Fang, "A thin film broadband absorber based on multi-sized...PEGylated phospholipid nanomicelles for in vivo imaging", Biomaterials, 32, 5880(2011). ( Impact Factor : 7.882) 4) Y. Jin, S. Xiao, N. A. Mortensen, and S

  12. Slow oscillations orchestrating fast oscillations and memory consolidation.

    Science.gov (United States)

    Mölle, Matthias; Born, Jan

    2011-01-01

    Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Gabor Wave Packet Method to Solve Plasma Wave Equations

    Energy Technology Data Exchange (ETDEWEB)

    A. Pletzer; C.K. Phillips; D.N. Smithe

    2003-06-18

    A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach.

  14. Reading and the Slow Learner.

    Science.gov (United States)

    Ediger, Marlow

    Advocates of high standards and expectations usually believe that gaps in reading achievement can be eliminated with good teaching, but slow readers need a specially designed reading curriculum. The teacher first needs to use an informal reading inventory to determine the student's reading level. Functioning generally on a higher level than…

  15. Programmed Instruction for Slow Learners

    Science.gov (United States)

    Holden, Eric; Roberts, Ted

    1973-01-01

    A description of a project which produced and provided programed learning materials for slow learners. These programs have been printed and distributed in over 30,000 free copies throughout Canada and have been a source of hope and assistance to teachers and parents. (Author)

  16. Nutrigenomics and inflammatory bowel diseases.

    Science.gov (United States)

    Ferguson, Lynnette R

    2010-07-01

    The field of nutrigenomics recognizes gene-diet interactions, with regard to both the impact of genetic variation on nutrient requirements, and conversely nutrient regulation of the expression of genes. Crohn's disease and ulcerative colitis are inflammatory bowel diseases for which twin studies reveal genetic susceptibility that is impacted by diet and environment. Apparently contradictory data on the role of diet in inflammatory bowel disease would be entirely explainable if genetic variability determined dietary requirements and intolerances. Considering Crohn's disease, we recognize three major classes of genes. The first of these involves bacterial recognition through pattern recognition receptors and autophagy genes, while the second act through secondary immune response, and the third concern epithelial barrier integrity. Despite genetic overlap with CD, the first two groups of genes appear to be less important in ulcerative colitis, while other genes, particularly those involved in barrier function, gain prominence. Case-control studies suggest that these different genetic groups reflect distinct dietary requirements. Such studies suggest nutrigenomic approaches to maintaining disease remission at present, and preventing disease development in the future.

  17. Small Bowel Dissemination of Coccidioidomycosis

    Directory of Open Access Journals (Sweden)

    Shengmei Zhou

    2015-01-01

    Full Text Available Gastrointestinal coccidioidomycosis is extremely rare, with less than 10 cases reported in the literature. We report a case of small bowel dissemination of coccidioidomycosis in a 21-year-old African American male with a history of living in San Joaquin Valley. The patient presented with one week of abdominal pain, nausea, shortness of breath, intermittent fever, and sweat, and one month of abdominal distention. A chest radiograph revealed complete effusion of left lung. A computed tomography scan of the abdomen showed diffuse small bowel thickening and enhancement, as well as omental and peritoneal nodules, and ascites. The coccidioidal complement fixation titer was 1 : 256. The duodenal biopsy revealed many spherules filled with round fungal endospores. Later, blood fungal culture showed positivity for Coccidioides immitis. The final diagnosis is disseminated coccidioidomycosis involving lungs, blood, and duodenum. Despite aggressive antifungal therapy, the patient’s clinical situation deteriorated and he succumbed to multisystem organ failure one and half months later. A high index of suspicion for gastrointestinal coccidioidomycosis should be maintained in patients from an endemic area presenting as abdominal distention and pain.

  18. 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...

  19. More Questions and Answers about Slow Learners

    Science.gov (United States)

    Abramowitz, Jack

    1977-01-01

    Presented are responses to questions often asked about slow learners, including: What kinds of materials can be used with slow learners? Is it advisable to deliver lecture lessons to slow learners? How do you start a class lesson? Can the teacher of slow learners reach every student? Teaching techniques and learning activities are described.…

  20. The unappreciated slowness of conventional tourism

    Directory of Open Access Journals (Sweden)

    G.R. Larsen

    2016-05-01

    Full Text Available Most tourists are not consciously engaging in ‘slow travel’, but a number of travel behaviours displayed by conventional tourists can be interpreted as slow travel behaviour. Based on Danish tourists’ engagement with the distances they travel across to reach their holiday destination, this paper explores unintended slow travel behaviours displayed by these tourists. None of the tourists participating in this research were consciously doing ‘slow travel’, and yet some of their most valued holiday memories are linked to slow travel behaviours. Based on the analysis of these unintended slow travel behaviours, this paper will discuss the potential this insight might hold for promotion of slow travel. If unappreciated and unintentional slow travel behaviours could be utilised in the deliberate effort of encouraging more people to travel slow, ‘slow travel’ will be in a better position to become integrated into conventional travel behaviour.

  1. 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

  2. Understanding Microbial Sensing in Inflammatory Bowel Disease Using Click Chemistry

    Science.gov (United States)

    2016-10-01

    AWARD NUMBER: W81XWH-15-1-0368 TITLE: Understanding Microbial Sensing in Inflammatory Bowel Disease Using Click Chemistry PRINCIPAL...AND SUBTITLE with Click Chemistry : : Understanding Microbial Sensing in Inflammatory Bowel Disease with Click Chemistry Understanding Microbial...Sensing in Inflammatory Bowel Disease with Click Chemistry 5a. CONTRACT NUMBER Understanding Microbial Sensing in Inflammatory Bowel Disease Using Click

  3. 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

  4. 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.

  5. Starch-entrapped microsphere fibers improve bowel habit but do not exhibit prebiotic capacity in those with unsatisfactory bowel habits: a phase I, randomized, double-blind, controlled human trial.

    Science.gov (United States)

    Rasmussen, Heather E; Hamaker, Bruce; Rajan, Kumar B; Mutlu, Ece; Green, Stefan J; Brown, Michael; Kaur, Amandeep; Keshavarzian, Ali

    2017-08-01

    Approximately one-third of individuals in the United States experience unsatisfactory bowel habits, and dietary intake, especially one low in fiber, could be partly responsible. We hypothesized that intake of a fermentable fiber (starch-entrapped microspheres, SM) that has a delayed, slow fermentation profile in vitro would improve bowel habit while exhibiting prebiotic capacity in those with self-described unsatisfactory bowel habits, all with minimal adverse effects. A total of 43 healthy volunteers completed a 3-month, double-blind, parallel-arm randomized clinical trial to assess the ability of a daily dose (9 or 12 g) of SM vs psyllium (12 g) to improve bowel habit, including stool consistency and frequency, and modify gut milieu through changes in stool microbiota and short-chain fatty acids while remaining tolerable through minimal gastrointestinal symptoms. All outcomes were compared before and after fiber treatment. Stool frequency significantly improved (P=.0003) in all groups after 3 months, but stool consistency improved only in both SM groups compared with psyllium. In addition, all groups self-reported a similar improvement in overall bowel habit with fiber intake. Both SM and psyllium resulted in minimal changes in microbiota composition and short-chain fatty acid concentrations. The present study suggests that supplementation with a delayed and slow-fermenting fiber in vitro may improve bowel habit in those with constipation, but further investigation is warranted to determine capacity to alter microbiota and fermentation profiles in humans. This trial was registered at ClinicalTrials.gov as NCT01210625. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Intestino Corto Short bowel syndrome

    Directory of Open Access Journals (Sweden)

    María Matilde Socarrás Suárez

    2004-06-01

    Full Text Available El intestino corto está asociado a pérdida o disfunción del intestino delgado por resección del mismo, que causa diarreas, tránsito intestinal acelerado, malabsorción intestinal, y eventualmente la pérdida de peso y el desgaste muscular. El objetivo de este trabajo fue actualizar el conocimiento acerca de este síndrome. Se realiza una revisión del tema de intestino corto donde se refiere a su definición, causas fundamentales frecuentes e infrecuentes en el niño y en el adulto, cómo se adapta el intestino a la resección de diferentes extensiones, las funciones del íleon terminal. Se hacen una valoración clínica inicial, con el interrogatorio médico, revisión minuciosa de la historia clínica para cuantificar la capacidad de absorción. Se habla de los síntomas y signos de deficiencia nutricional. Se explican las estrategias del tratamiento, que tienen 3 etapas de evolución clínica. Se concluye que se indica la dietoterapia adecuada según el estado nutricional del paciente y la resección intestinal realizada, evitando las complicaciones para lograr una calidad máxima de vidaShort bowel is associated with loss or dysfunction of the small bowel due to its resection, which causes diarrheas, accelerated intestinal transit, intestinal malabsorption and, eventually, weight loss ansd muscular waste. The objective of this paper was to update knowledge about this syndrome. A review of the short intestine topic is made, making reference to its definition, common and uncommon main cuases in the child and adult, how the bowel adapts itslef to resection of different extensions, and the functions of the terminal ileum. An initial clinical assessment is made with the medical questionnaire and a detailed review of the medical history to quantify the absorption capacity. The symptoms and signs of nutritional deficiency are dealt with. The strategies of the treatment consisting of 3 stages of clinical evolution are explained. It is concluded

  7. 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......, indicating that CC is a pan-intestinal disease. In small-intestinal disease, the intestinal barrier function may be impaired, and the permeability of the small intestine altered. The purpose of this research was to study small-bowel function in patients with CC as expressed by intestinal permeability....

  8. Modulational instability of plasma waves in two dimensions

    DEFF Research Database (Denmark)

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

    1996-01-01

    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......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...... of nonlinear waves in dispersive media....

  9. Generalized Slow Roll for Tensors

    OpenAIRE

    Hu, Wayne

    2014-01-01

    The recent BICEP2 detection of degree scale CMB B-mode polarization, coupled with a deficit of observed power in large angle temperature anisotropy, suggest that the slow-roll parameter $\\epsilon_H$, the fractional variation in the Hubble rate per efold, is both relatively large and may evolve from an even larger value on scales greater than the horizon at recombination. The relatively large tensor contribution implied also requires finite matching features in the tensor power spectrum for an...

  10. 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.

  11. Infections in inflammatory bowel disease.

    Science.gov (United States)

    Rodríguez de Santiago, Enrique; Albillos Martínez, Agustín; López-Sanromán, Antonio

    2017-05-10

    Patients with inflammatory bowel disease constitute a population with a special predisposition to develop bacterial, viral and fungal infections. Iatrogenic immunosuppression, frequent contact with healthcare facilities and surgical interventions are some of the risk factors that explain why these infections are one of the main causes of morbi-mortality in this disease. Some of these infections follow a subtle and paucisymptomatic evolution; their diagnosis and management may become a real challenge for the attending physician if their screening is not systematized or they are not considered in the differential diagnosis. The objective of this review is to provide an update from a practical and concise perspective on the knowledge regarding the epidemiology, prevention, diagnosis and treatment of the most common infections. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  12. 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.

  13. Biomarkers in inflammatory bowel diseases

    DEFF Research Database (Denmark)

    Bennike, Tue; Birkelund, Svend; Stensballe, Allan

    2014-01-01

    Unambiguous diagnosis of the two main forms of inflammatory bowel diseases (IBD): Ulcerative colitis (UC) and Crohn's disease (CD), represents a challenge in the early stages of the diseases. The diagnosis may be established several years after the debut of symptoms. Hence, protein biomarkers...... for early and accurate diagnostic could help clinicians improve treatment of the individual patients. Moreover, the biomarkers could aid physicians to predict disease courses and in this way, identify patients in need of intensive treatment. Patients with low risk of disease flares may avoid treatment...... with medications with the concomitant risk of adverse events. In addition, identification of disease and course specific biomarker profiles can be used to identify biological pathways involved in the disease development and treatment. Knowledge of disease mechanisms in general can lead to improved future...

  14. Thalidomide for inflammatory bowel disease

    Science.gov (United States)

    Bramuzzo, Matteo; Ventura, Alessandro; Martelossi, Stefano; Lazzerini, Marzia

    2016-01-01

    Abstract Background: Thalidomide is an immunomodulatory drug used in the experimental treatment of refractory Crohn disease and ulcerative colitis. We aimed to review the existing evidence on the efficacy and safety of thalidomide in the treatment of inflammatory bowel diseases. Methods: CENTRAL, MEDLINE, LILACS, POPLINE, CINHAL, and Web of Science were searched in March 2016. Manual search included conference and reference lists. All types of studies, except single case reports, were included. Outcomes evaluated were: induction of remission; maintenance of remission; steroid reduction; effect on penetrating Crohn disease; endoscopic remission; adverse events. Results: The research strategies retrieved 722 papers. Two randomized controlled trials and 29 uncontrolled studies for a total of 489 patients matched the inclusion criteria. Thalidomide induced a clinical response in 296/427 (69.3%) patients. Clinical remission was achieved in 220/427 (51.5%) cases. Maintenance of remission was reported in 128/160 (80.0%) patients at 6 months and in 96/133 (72.2%) at 12 months. Reduction in steroid dosage was reported in 109/152 (71.7%) patients. Fistulas improved in 49/81 (60.5%) cases and closed in 28/81 (34.6%). Endoscopic improvement was observed in 46/66 (69.7%) and complete mucosal healing in 35/66 (53.0%) patients. Cumulative incidence of total adverse events and of those leading to drug suspension was 75.6 and 19.7/1000 patient-months, respectively. Neurological disturbances accounted for 341/530 (64.3%) adverse events and were the most frequent cause of drug withdrawal. Conclusion: Existing evidence suggests that thalidomide may be a valid treatment option for patients with inflammatory bowel diseases refractory to other first- and second-line treatments. PMID:27472695

  15. Endoscopic evaluation of surgically altered bowel in patients with inflammatory bowel diseases.

    Science.gov (United States)

    Sinh, Preetika; Shen, Bo

    2015-06-01

    Patients with inflammatory bowel diseases often undergo surgical procedures for medically refractory disease or colitis associated dysplasia. Endoscopic evaluation of the surgically altered bowel is often needed to assess for disease recurrence, its severity, and for therapy. It is important to obtain and review the operative report and abdominal imaging before performing the endoscopy. Diagnostic and therapeutic endoscopy can be safely performed in most patients with inflammatory bowel disease with altered bowel anatomy under conscious sedation without fluoroscopy. Carefully planned stricture therapy with balloon dilation or needle knife stricturotomy can be performed for simple, short, and fibrotic strictures. A multidisciplinary approach involving a team of endoscopist, endoscopy nurse, colorectal surgeon, gastrointestinal pathologist, and gastrointestinal radiologist is important for a safe and effective endoscopy. We attempt to review the aspects that need consideration before the endoscopy, the technique of endoscopy, and briefly the therapies that can be performed during endoscopy of the bowel through an ileostomy, a colostomy, in the diverted large bowel or ileal pouch, and small bowel after stricturoplasty and bowel bypass surgery in patients with inflammatory bowel diseases.

  16. 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.

  17. Caustics of atmospheric waves

    Science.gov (United States)

    Godin, Oleg A.

    2015-04-01

    Much like light and sound, acoustic-gravity waves in inhomogeneous atmosphere often have a caustic or caustics, where the ray theory predicts unphysical, divergent values of the wave amplitude and needs to be modified. Increase of the wave magnitude in the vicinity of a caustic makes such vicinities of primary interest in a number of problems, where a signal needs to be separated from a background noise. The value of wave focusing near caustics should be carefully quantified in order to evaluate possible nonlinearities promoted by the focusing. Physical understanding of the wave field in the vicinity of a caustic is also important for understanding of the wave reflection from and transmission (tunneling) through the caustic. To our knowledge, in contrast to caustics of acoustic, electromagnetic, and seismic waves as well as gravity waves in incompressible fluids, asymptotics of acoustic-gravity waves in the vicinity of a caustic have never been studied systematically. In this paper, we fill this gap. Atmospheric waves are considered as linear acoustic-gravity waves in a neutral, horizontally stratified, moving ideal gas of variable composition. Air temperature and wind velocity are assumed to be gradually varying functions of height, and slowness of these variations determines the large parameter of the problem. The scale height of the atmosphere can be large or small compared to the vertical wavelength. It is found that the uniform asymptotics of the wave field in the presence of a simple caustic can be expressed in terms of the Airy function and its derivative. As for the acoustic waves, the argument of the Airy function is expressed in terms of the eikonal calculated in the ray, or WKB, approximation. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity waves, plays an important role in the caustic asymptotics. In the uniform asymptotics, the terms with the Airy function and its derivative are weighted by cosine

  18. 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

  19. 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...... permeability. MATERIAL AND METHODS: Ten patients with CC and chronic diarrhoea participated in the study. Coeliac disease was excluded by small-bowel biopsy and/or serology. Intestinal permeability was assessed as urinary excretion (ratios) 2, 4 and 6 h after ingestion of 14C-labelled mannitol (14C......-intestinal biopsies, indicating that CC is a pan-intestinal disease. In small-intestinal disease, the intestinal barrier function may be impaired, and the permeability of the small intestine altered. The purpose of this research was to study small-bowel function in patients with CC as expressed by intestinal...

  20. Recent advances in inflammatory bowel disease

    African Journals Online (AJOL)

    2009-05-12

    analysis comparing capsule endoscopy with small- bowel barium radiology, colonoscopy with ileoscopy, computer tomography ..... Each tablet contains Aspirin 81mg. Reg.No.: 29/2.7/0767. Pharmafrica (Pty) Ltd, 33 Hulbert Road, ...

  1. Stem cell therapy for inflammatory bowel disease

    NARCIS (Netherlands)

    Duijvestein, Marjolijn

    2012-01-01

    Hematopoietic stem cell transplantation (HSCT) and mesenchymal stromal (MSC) cell therapy are currently under investigation as novel therapies for inflammatory bowel diseases (IBD). Hematopoietic stem cells are thought to repopulate the immune system and reset the immunological response to luminal

  2. 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...

  3. Symptoms and Causes of Irritable Bowel Syndrome

    Science.gov (United States)

    ... you haven’t finished a bowel movement whitish mucus in your stool Women with IBS often have ... as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of ...

  4. 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.

  5. Hirschsprung disease-Bowel function beyond childhood.

    Science.gov (United States)

    Wester, Tomas; Granström, Anna Löf

    2017-10-01

    Hirschsprung disease is a developmental defect of the enteric nervous system characterized by lack of enteric neurons in the distal hindgut. There are numerous reports on short-term outcomes indicating that impaired bowel function is common. Recently, several controlled studies show that bowel function outcomes are affected beyond childhood, in adolescents and adults, compared with healthy control subjects. Constipation and fecal incontinence are common. The impaired bowel function appears to have a negative impact on quality of life, although, a majority of patients have adapted to their symptoms. On the other hand, Hirschsprung disease seems to have limited impact on education and occupation in adult life. The aim of this review was to summarize current knowledge of bowel function outcome beyond childhood in patients with Hirschsprung disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Building a second brain in the bowel

    National Research Council Canada - National Science Library

    Avetisyan, Marina; Schill, Ellen Merrick; Heuckeroth, Robert O

    2015-01-01

    The enteric nervous system (ENS) is sometimes called the "second brain" because of the diversity of neuronal cell types and complex, integrated circuits that permit the ENS to autonomously regulate many processes in the bowel...

  7. 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...

  8. Implementation of the victoria bowel performance scale.

    Science.gov (United States)

    Hawley, Philippa; Barwich, Doris; Kirk, Lisa

    2011-12-01

    There is a lack of evidence to guide constipation management in patients receiving palliative care. Data collection requires the systematic use of validated assessment tools. The objective of this study was to assess the usefulness of the Victoria Bowel Performance Scale (BPS) as an audit tool. Charts were reviewed before and after the implementation of a program to monitor constipation through repeated use of the Victoria Bowel Scale. The program was initiated at three oncology pain and symptom management clinics, four palliative care units, and four residential hospices. An additional "control" palliative care unit introduced new nursing assessment tools without the new scale. The Victoria BPS was recorded at 86% of 192 postimplementation outpatient clinic visits and was easy to use in this setting. Documentation of bowel performance at comparable visits improved from 44% to 66% (Passessment tool, uniquely incorporating the patient's usual bowel function. Modifications to the scale have been made to improve clarity and allow for the expected drop in bowel activity seen in end-of-life care. Considerable educational effort and appropriate organization of the charts are required for optimal implementation. The proportion of revised BPS scores ranging from -1 to +1 is proposed as an indicator of satisfactory bowel management for clinical, audit, and research purposes. Copyright © 2011 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved.

  9. Study and analysis on slow light in photonic crystal waveguide

    Science.gov (United States)

    Dang, Shuzhen; Shu, Jing

    2017-02-01

    Slow light is to reduce the light propagation speed in the medium. In recent years, because slow light technology is the key to achieving all-optical network technologies constitute optics, it attracted people's attention. Compared with other methods, photonic crystal waveguides provide slow light with many adventages, especially we can fine tune the structure to control the performance of the slow-light. Because the two-dimensional triangular lattice photonic crystal is easier to form band gaps than two-dimensional cubic lattice photonic crystal, the circular dielectric rod is easier to form band gaps than square dielectric cylinder, when the photonic crystal lattice vector angle is greater than 60 degrees, it can make the performance of slow light more excellent. So in this paper,we will rotate the cubic lattice 45 degrees counterclockwise. By reducing the radius of middle row of medium column to form the line defect; Additionly, we design a coupled cavity waveguide. Using the plane wave expansion method (PWE), we have analyzed the dispersion curves of the guided mode, the corresponding group refractive index and group velocity dispersion of slow light. For the line defected waveguide, we have realized the group refractive index changing from 8.1 to 84.8 by fine tuning the radius of the defective rod, the position and radius of the first row of the dielectric cylinder close to the waveguide. For the coupled cavity waveguide, we have realized the group refractive index changing from 16 to 79 by fine tuning the radius of the defective rod.

  10. Fast wave current drive: Experimental status and reactor prospects

    Energy Technology Data Exchange (ETDEWEB)

    Ehst, D.A.

    1988-03-01

    The fast wave is one of the two possible wave polarizations which propagate according to the basic theory of cold plasmas. It is distinguished from the other (slow wave) branch by having an electric field vector which is mainly orthogonal to the confining magnetic field of the plasma. The plasma and fast wave qualitatively assume different behavior depending on the frequency range of the launched wave. The high frequency fast wave (HFFW), with a frequency (..omega..2..pi.. )approximately) GHz) much higher than the ion cyclotron frequency (..cap omega../sub i/), suffers electron Landau damping and drives current by supplying parallel momentum to superthermal electrons in a fashion similar to lower hybrid (slow wave) current drive. In the simple theory the HFFW should be superior to the slow wave and can propagate to very high density and temperature without impediment. Experiments, however, have not conclusively shown that HFFW current drive can be achieved at densities above the slow wave current drive limit, possibly due to conversion of the launched fast waves into slow waves by density fluctuations. Alternatively, the low frequency fast wave (LFFW), with frequencies ()approxreverse arrowlt) 100 MHz) only a few times the ion cyclotron frequency, is damped by electron Landau damping and, in a hot plasma ()approxreverse arrowgt) 10 keV), by electron transit time magnetic pumping; current drive is achieved by pushing superthermal electrons, and efficiency is prediocted to be slightly better than for lower hybrid current drive. Most significantly, the slow wave does not propagate in high density plasma when ..omega.. )approximately) ..cap omega../sub i/, so parasitic coupling to the slow wave can be avoided, and no density and temperture limitations are foreseen. Experiments with fast wve current drive invariably find current drive efficiency as good as obtained in lower hybrid experiments at comparable, low temperatures. 45 refs., 4 figs., 1 tab

  11. The CUORE slow monitoring systems

    Science.gov (United States)

    Gladstone, L.; Biare, D.; Cappelli, L.; Cushman, J. S.; Del Corso, F.; Fujikawa, B. K.; Hickerson, K. P.; Moggi, N.; Pagliarone, C. E.; Schmidt, B.; Wagaarachchi, S. L.; Welliver, B.; Winslow, L. A.

    2017-09-01

    CUORE is a cryogenic experiment searching primarily for neutrinoless double decay in 130Te. It will begin data-taking operations in 2016. To monitor the cryostat and detector during commissioning and data taking, we have designed and developed Slow Monitoring systems. In addition to real-time systems using LabVIEW, we have an alarm, analysis, and archiving website that uses MongoDB, AngularJS, and Bootstrap software. These modern, state of the art software packages make the monitoring system transparent, easily maintainable, and accessible on many platforms including mobile devices.

  12. Corpuscular slow-roll inflation

    Science.gov (United States)

    Casadio, Roberto; Giugno, Andrea; Giusti, Andrea

    2018-01-01

    We show that a corpuscular description of gravity can lead to an inflationary scenario similar to Starobinsky's model without requiring the introduction of the inflaton field. All relevant properties are determined by the number of gravitons in the cosmological condensate or, equivalently, by their Compton length. In particular, the relation between the Hubble parameter H and its time derivative H ˙ required by cosmic microwave background observations at the end of inflation, as well as the (minimum) initial value of the slow-roll parameter, are naturally obtained from the Compton size of the condensate.

  13. Resistance Training May Slow MS, Study Says

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_167617.html Resistance Training May Slow MS, Study Says Scans revealed ... 4, 2017 FRIDAY, Aug. 4, 2017 (HealthDay News) -- Resistance training may help slow progression of multiple sclerosis, ...

  14. 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....

  15. Lifestyle Changes Might Prevent or Slow Dementia

    Science.gov (United States)

    ... 166825.html Lifestyle Changes Might Prevent or Slow Dementia The public should be aware of this encouraging ... to your lifestyle might delay the start of dementia or slow its progression, a new report suggests. ...

  16. Factors Contributing Decreased Performance Of Slow Learners

    National Research Council Canada - National Science Library

    Dr. L. Kannan; Dr. P. V. Vijayaragavan; Dr. Pankaj. B. Shah; Dr. Suganathan. S; Dr. Praveena .P

    2015-01-01

    ... these students are called as slow learnersStruggle learners. There should be a designed study to foster discussion about diagnosing particular problems that contribute with meeting objectives of slow learners...

  17. Slow shock interactions in the heliosphere using an adaptive grid MHD model

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2005-03-01

    Full Text Available A one-dimensional (1-D, time-dependent, adaptive-grid MHD model with solar wind structure has been used in the past to study the interaction of shocks. In the present study, we wish to study some fundamental processes that may be associated with slow shock genesis and their possible interactions with other discontinuities. This adaptive-grid model, suitable for appropriate spatial and temporal numerical simulations, is used for this purpose because its finer grid sizes in the vicinity of the steep gradients at shocks make it possible to delineate the physical parameters on both sides of the shocks. We found that a perturbation with deceleration of solar wind will generate an ensemble consisting of a forward slow shock, a fast forward wave and a reverse slow shock. On the other hand, a perturbation with an increase in acceleration of solar wind will generate both a slow shock and a fast shock. These two perturbations, although not unique, may be representative of momentum and pressure changes at the solar surface. During the transition of a fast shock overtaking a slow shock from behind, the slow shock might disappear temporarily. Also, during the process of the merging of two slow shocks, a slow shock-like structure is formed first; later, the slow shock-like structure evolves into an intermediate shock-like structure. This intermediate shock-like structure then evolves into an intermediate wave and a slow shock-like structure. Finally, the slow shock-like structure evolves into a slow shock, but the intermediate wave disappears by interacting with the non-uniform solar wind. This complex behavior demonstrates the non-unique nature of the formation of slow shocks, intermediate shocks and their derivative structures. We emphasize the main aim of this work to be both: (a non-unique input physical parameters to explain the paucity of observed slow shocks, as well as (b the impossibility of backward tracing to the history of input boundary

  18. Slow shock interactions in the heliosphere using an adaptive grid MHD model

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2005-03-01

    Full Text Available A one-dimensional (1-D, time-dependent, adaptive-grid MHD model with solar wind structure has been used in the past to study the interaction of shocks. In the present study, we wish to study some fundamental processes that may be associated with slow shock genesis and their possible interactions with other discontinuities. This adaptive-grid model, suitable for appropriate spatial and temporal numerical simulations, is used for this purpose because its finer grid sizes in the vicinity of the steep gradients at shocks make it possible to delineate the physical parameters on both sides of the shocks. We found that a perturbation with deceleration of solar wind will generate an ensemble consisting of a forward slow shock, a fast forward wave and a reverse slow shock. On the other hand, a perturbation with an increase in acceleration of solar wind will generate both a slow shock and a fast shock. These two perturbations, although not unique, may be representative of momentum and pressure changes at the solar surface.

    During the transition of a fast shock overtaking a slow shock from behind, the slow shock might disappear temporarily. Also, during the process of the merging of two slow shocks, a slow shock-like structure is formed first; later, the slow shock-like structure evolves into an intermediate shock-like structure. This intermediate shock-like structure then evolves into an intermediate wave and a slow shock-like structure. Finally, the slow shock-like structure evolves into a slow shock, but the intermediate wave disappears by interacting with the non-uniform solar wind. This complex behavior demonstrates the non-unique nature of the formation of slow shocks, intermediate shocks and their derivative structures.

    We emphasize the main aim of this work to be both: (a non-unique input physical parameters to explain the paucity of observed slow shocks, as well as (b the impossibility

  19. Connecting slow earthquakes to huge earthquakes

    OpenAIRE

    Obara, Kazushige; Kato, Aitaro

    2016-01-01

    Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of th...

  20. Low-FODMAP diet reduces irritable bowel symptoms in patients with inflammatory bowel disease

    DEFF Research Database (Denmark)

    Pedersen, Natalia; Ankersen, Dorit Vedel; Felding, Maria

    2017-01-01

    AIM: To investigate the effect of a low-FODMAP diet on irritable bowel syndrome (IBS)-like symptoms in patients with inflammatory bowel disease (IBD). METHODS: This was a randomised controlled open-label trial of patients with IBD in remission or with mild-to-moderate disease and coexisting IBS...

  1. Slow Learners: Are Educators Leaving Them Behind?

    Science.gov (United States)

    Kaznowski, Kimberly

    2004-01-01

    This study compared the school performance of a sample of slow learners who qualified for special education as learning disabled with a sample of slow learners who did not qualify for special education. The intent of the study was to determine which group of slow learners was more successful in school in order to know if special education or…

  2. Don't Forget the Slow Learner.

    Science.gov (United States)

    Watson, Daniel L.; Rangel, Lyle

    1989-01-01

    Advocates cooperative learning as an effective tool for reaching slow learners, by bridging the gaps between the learning styles of slow learners and the teaching requirements of the classroom, resulting in improved academic performance for both slow learners and high achievers. (SR)

  3. Loss engineered slow light waveguides.

    Science.gov (United States)

    O'Faolain, L; Schulz, S A; Beggs, D M; White, T P; Spasenović, M; Kuipers, L; Morichetti, F; Melloni, A; Mazoyer, S; Hugonin, J P; Lalanne, P; Krauss, T F

    2010-12-20

    Slow light devices such as photonic crystal waveguides (PhCW) and coupled resonator optical waveguides (CROW) have much promise for optical signal processing applications and a number of successful demonstrations underpinning this promise have already been made. Most of these applications are limited by propagation losses, especially for higher group indices. These losses are caused by technological imperfections ("extrinsic loss") that cause scattering of light from the waveguide mode. The relationship between this loss and the group velocity is complex and until now has not been fully understood. Here, we present a comprehensive explanation of the extrinsic loss mechanisms in PhC waveguides and address some misconceptions surrounding loss and slow light that have arisen in recent years. We develop a theoretical model that accurately describes the loss spectra of PhC waveguides. One of the key insights of the model is that the entire hole contributes coherently to the scattering process, in contrast to previous models that added up the scattering from short sections incoherently. As a result, we have already realised waveguides with significantly lower losses than comparable photonic crystal waveguides as well as achieving propagation losses, in units of loss per unit time (dB/ns) that are even lower than those of state-of-the-art coupled resonator optical waveguides based on silicon photonic wires. The model will enable more advanced designs with further loss reduction within existing technological constraints.

  4. Further Investigations of Slow Lightning

    Science.gov (United States)

    Stephan, Karl; Sheleg, Gil

    2013-09-01

    The phenomenon of ``slow lightning'' is a new type of tracking or sliding atmospheric-pressure resistive-barrier discharge on the surface of a weakly conducting electrolyte. It occurs during the production of water plasmoids (also called ``Gatchina discharges'') in which a high-voltage capacitor is discharged into an insulated cathode in limited surface contact with the electrolyte. Unlike conventional dielectric-barrier and most other resistive-barrier discharges, these novel discharges propagate on the surface relatively slowly, spreading at a speed of 1-10 meters per second. We have investigated this phenomenon in several ways, using high-speed videography, time- and space-resolved spectroscopy, and current-density profiling. The plasma produced at cathode spots forms the plasmoid, and this plasma is distinct from the plasma in the slow-lightning discharge above the electrolyte. The primary visible emission from the latter discharge is a continuum, probably due to free-bound transitions, although an N2 + band is also present as well as intense emission from OH radicals under certain conditions. Possible applications of this phenomenon include water purification and pollution control.

  5. Exclusion Process with Slow Boundary

    Science.gov (United States)

    Baldasso, Rangel; Menezes, Otávio; Neumann, Adriana; Souza, Rafael R.

    2017-06-01

    We study the hydrodynamic and the hydrostatic behavior of the simple symmetric exclusion process with slow boundary. The term slow boundary means that particles can be born or die at the boundary sites, at a rate proportional to N^{-θ }, where θ > 0 and N is the scaling parameter. In the bulk, the particles exchange rate is equal to 1. In the hydrostatic scenario, we obtain three different linear profiles, depending on the value of the parameter θ ; in the hydrodynamic scenario, we obtain that the time evolution of the spatial density of particles, in the diffusive scaling, is given by the weak solution of the heat equation, with boundary conditions that depend on θ . If θ \\in (0,1), we get Dirichlet boundary conditions, (which is the same behavior if θ =0, see Farfán in Hydrostatics, statical and dynamical large deviations of boundary driven gradient symmetric exclusion processes, 2008); if θ =1, we get Robin boundary conditions; and, if θ \\in (1,∞), we get Neumann boundary conditions.

  6. 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.

  7. Fast Plane Wave Imaging

    DEFF Research Database (Denmark)

    Jensen, Jonas

    This PhD project investigates and further develops methods for ultrasound plane wave imaging and blood flow estimation with the objective of overcoming some of the major limitations in conventional ultrasound systems, which are related to low frame rates and only estimation of velocities along...... the ultrasound beam. The first part of the contribution investigates the compromise between frame rate and plane wave image quality including the influence of grating lobes from a λ-pitch transducer. A method for optimizing the image quality is suggested, and it is shown that the frame rate can be increased...... healthy volunteers. Complex flow patterns were measured in an anthropomorphic flow phantom and showed good agreement with the velocity field simulated using computational fluid dynamics. The last part of the contribution investigates two clinical applications. Plane wave imaging was used for slow velocity...

  8. 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.)

  9. Human scalp recorded sigma activity is modulated by slow EEG oscillations during deep sleep.

    Science.gov (United States)

    Fell, Jürgen; Elfadil, Hakim; Röschke, Joachim; Burr, Wieland; Klaver, Peter; Elger, Christian E; Fernández, Guillén

    2002-07-01

    The EEG during deep sleep exhibits a distinct cortically generated slow oscillation of around and below 1 Hz which can be distinguished from other delta (0.5-3.5 Hz) activity. Intracranial studies showed that this slow oscillation triggers and groups cortical network firing. In the present study, we examined whether the phases of the slow oscillation during sleep stage 4 are correlated with the magnitude of sigma (12-16 Hz) and gamma (> 20 Hz) scalp activity. For this purpose, 10-min segments of uninterrupted stage 4 sleep EEG from 9 subjects were analyzed by applying wavelet techniques. We found that scalp recorded sigma, but not gamma, activity is modulated by the phases of the slow oscillation during deep sleep. Enhancement of sigma activity was observed to be triggered by the peak of the surface positive slow wave component, whereas reduction of sigma activity started around the peak of the negative component.

  10. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  11. Seismic shear waves as Foucault pendulum

    Science.gov (United States)

    Snieder, Roel; Sens-Schönfelder, Christoph; Ruigrok, Elmer; Shiomi, Katsuhiko

    2016-03-01

    Earth's rotation causes splitting of normal modes. Wave fronts and rays are, however, not affected by Earth's rotation, as we show theoretically and with observations made with USArray. We derive that the Coriolis force causes a small transverse component for P waves and a small longitudinal component for S waves. More importantly, Earth's rotation leads to a slow rotation of the transverse polarization of S waves; during the propagation of S waves the particle motion behaves just like a Foucault pendulum. The polarization plane of shear waves counteracts Earth's rotation and rotates clockwise in the Northern Hemisphere. The rotation rate is independent of the wave frequency and is purely geometric, like the Berry phase. Using the polarization of ScS and ScS2 waves, we show that the Foucault-like rotation of the S wave polarization can be observed. This can affect the determination of source mechanisms and the interpretation of observed SKS splitting.

  12. Treatment of Irritable Bowel Syndrome.

    Science.gov (United States)

    Spiller, Robin C.

    2003-08-01

    Irritable bowel syndrome (IBS) is an extremely common cause of consultation, and at present is diagnosed on the basis of symptoms and a few simple exclusion tests. Exclusion diets can be successful, but many patients have already attempted and failed such treatments before consulting. Anxiety and somatization may be an important driver of consultation. Patients' concerns should be understood and addressed. Those with prominent psychiatric disease may benefit from psychotherapy. Hypnotherapy benefits symptoms in those without psychologic disturbance, but its availability is limited. Antidepressants are effective in improving both mood and IBS symptoms globally, and the evidence is particularly good for tricyclic antidepressants. Although antispasmodics are currently the most commonly prescribed drugs, most responses (75%) are due to the placebo effect and not specific to the drug. Bulk laxatives such as ispaghula can increase stool frequency and help pain, but bloating may be aggravated. Loperamide is effective treatment for urgency and loose stools, but less effective for bloating and pain. 5-HT(3) antagonists such as alosetron improve urgency, stool consistency, and pain in diarrhea-predominant-IBS. The 5-HT(4) agonist tegaserod shows modest benefit in constipation-predominant IBS, improving stool frequency, consistency, and bloating as well as global improvement. There are many new drugs, such as cholecystokinin, neurokinin, and corticotropin receptor antagonists, in development.

  13. Nutrition in inflammatory bowel disease

    Science.gov (United States)

    Martínez Gómez, María Josefa; Melián Fernández, Cristóbal; Romeo Donlo, María

    2016-07-12

    Inflammatory bowel disease (IBD) is a chronic pathology that has an outbreaks course that in recent years have seen an increase in incidence, especially at younger ages. Malnutrition is frequently associated with this condition, therefore, it is very important to ensure a right nutritional intervention, especially in pediatric patients, to ensure an optimal growth and also an improvement in the clinic. Our goal will be updated the role of nutrition in this disease and in its treatment based on the published evidence. Malnutrition in these patients is frequent and is influenced by various factors such as, decreased food intake, increased nutrient requirements, increased protein loss and malabsorption of nutrients. Therefore there should be a nutritional monitoring of all of them, in which anthropometric measurements, laboratory tests and densitometry were made to establish the needs and sufficient caloric intake tailored to each patient. The use of enteral nutrition as a treatment in Crohn’s disease with mild to moderate outbreak in child population, is amply demonstrated, has even shown to be superior to the use of corticosteroids. Therefore we can conclude by stressing that nutritional intervention is a mainstay in the management of patients with IBD, which aims to prevent and / or control disease-related malnutrition to decrease morbidity and mortality and improve quality of life.

  14. Immunopathology of inflammatory bowel disease.

    Science.gov (United States)

    Wallace, Kori L; Zheng, Li-Bo; Kanazawa, Yoshitake; Shih, David Q

    2014-01-07

    Inflammatory bowel disease (IBD) results from a complex series of interactions between susceptibility genes, the environment, and the immune system. The host microbiome, as well as viruses and fungi, play important roles in the development of IBD either by causing inflammation directly or indirectly through an altered immune system. New technologies have allowed researchers to be able to quantify the various components of the microbiome, which will allow for future developments in the etiology of IBD. Various components of the mucosal immune system are implicated in the pathogenesis of IBD and include intestinal epithelial cells, innate lymphoid cells, cells of the innate (macrophages/monocytes, neutrophils, and dendritic cells) and adaptive (T-cells and B-cells) immune system, and their secreted mediators (cytokines and chemokines). Either a mucosal susceptibility or defect in sampling of gut luminal antigen, possibly through the process of autophagy, leads to activation of innate immune response that may be mediated by enhanced toll-like receptor activity. The antigen presenting cells then mediate the differentiation of naïve T-cells into effector T helper (Th) cells, including Th1, Th2, and Th17, which alter gut homeostasis and lead to IBD. In this review, the effects of these components in the immunopathogenesis of IBD will be discussed.

  15. 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. Copyright © 2015 the American Physiological Society.

  16. Pregnancy and Inflammatory Bowel Disease.

    Science.gov (United States)

    Hashash, Jana G; Kane, Sunanda

    2015-02-01

    Many patients with inflammatory bowel disease (IBD), whether Crohn's disease or ulcerative colitis, are of reproductive age. Young women with IBD are usually very worried about their fertility, the activity of their disease during pregnancy, the heritability of the disease to their unborn child, and the effect of their underlying IBD on the pregnancy itself. Additionally, patients express concerns about using IBD medications during pregnancy, fearing that the medications may negatively affect the fetus. For this reason, it is of the utmost importance that gastroenterologists and patients with IBD be aware of the effect of IBD on pregnancy, the effect of pregnancy on IBD, and the effect of IBD medications on the fetus and on pregnancy outcomes. Increasing the awareness of patients with IBD about the importance of maintaining disease remission at the time of conception and throughout pregnancy is key to improving the outcomes of both mothers and fetuses. This article addresses the fertility of patients with IBD, the effect of pregnancy on disease activity, and the effect of IBD on pregnancy. Also discussed are which IBD medications can be used during conception and pregnancy and which medications must be avoided.

  17. Inflammatory bowel disease in pregnancy.

    Science.gov (United States)

    Beaulieu, Dawn B; Kane, Sunanda

    2011-06-14

    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.

  18. [Treatment of inflammatory bowel diseases].

    Science.gov (United States)

    Gomollón, Fernando

    2015-09-01

    In addition to immunosuppressive drugs and anti-TNF, there are a number of new options in the treatment of inflammatory bowel diseases. Vedolizumab has been approved by the FDA and EMA and has demonstrated utility both in the treatment of ulcerative colitis (UC) and Crohn's disease (CD), even in anti-TNF refractory patients. Other monoclonal antibodies with different targets such as PF-005447659 (antiMAd-CAM1), ustekinumab (anti-IL23/IL12) or MEDI2070 (anti-IL23) have shown promising results in distinct clinical scenarios. Mongersen (antisense oligonucleotide anti-Smad7) and oznimod (an SP-1 modulator) are new alternatives with proven efficacy in clinical trials in CD and UC, respectively. Some data suggest that faecal microbiota transplantation could be efficacious in individual patients, although controlled data do not show clear differences with placebo. Autologous stem-cell transplantation has shown long-term efficacy in "ultra-refractory" CD. The number of possible treatments is constantly increasing, and future research should focus both on the selection of the most appropriate treatment for any given patient and on comparative trials between options. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  19. [Irritable bowel syndrome in children].

    Science.gov (United States)

    Ansaldi, N; Villata, L; Santini, B; Fantino, N; Robazza, V; Ciervo, T; Barbera, C; Elia, G; Oderda, G

    1987-01-01

    The irritable bowel syndrome (IBS) is the most common chronic functional gastroenterological disorder both in adults and in children. In this study we evaluate the different aspects of this syndrome, comparing our observations on 332 children with other studies. Epidemiological data (frequency, sex, age) are examined so as the family histories of gastroenterological disorders. We take in account several pathogenic hypotheses, especially with reference to the alterations of gastrointestinal motility, which could be caused by several factors (psychological, prostaglandins, bile acids, etc.). The clinical picture is very variable, variations depending on the age of children and on the time of onset of IBS. The colic of neonate, caused by retention of air, is the main symptom in the first months of life, followed by chronic diarrhoea, also defined as toddler's diarrhoea, sometime alternating with constipation. In later childhood, recurrent abdominal pain represents a common complaint, in association with diarrhoea or constipation. The principal steps for a proper diagnosis so as the main differential diagnosis are defined. We explain the most important features of management (reassuring parents, free diet), excluding prescription of drugs, that produce only a transitory and symptomatic relief, so as elimination diets, that cause only a failure to thrive without any improvement of symptoms.

  20. GEODYNAMIC WAVES AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. V. Vikulin

    2015-09-01

    Full Text Available  Gravity phenomena related to the Earth movements in the Solar System and through the Galaxy are reviewed. Such movements are manifested by geological processes on the Earth and correlate with geophysical fields of the Earth. It is concluded that geodynamic processes and the gravity phenomena (including those of cosmic nature are related.  The state of the geomedium composed of blocks is determined by stresses with force moment and by slow rotational waves that are considered as a new type of movements [Vikulin, 2008, 2010]. It is shown that the geomedium has typical rheid properties [Carey, 1954], specifically an ability to flow while being in the solid state [Leonov, 2008]. Within the framework of the rotational model with a symmetric stress tensor, which is developed by the authors [Vikulin, Ivanchin, 1998; Vikulin et al., 2012a, 2013], such movement of the geomedium may explain the energy-saturated state of the geomedium and a possibility of its movements in the form of vortex geological structures [Lee, 1928]. The article discusses the gravity wave detection method based on the concept of interactions between gravity waves and crustal blocks [Braginsky et al., 1985]. It is concluded that gravity waves can be recorded by the proposed technique that detects slow rotational waves. It is shown that geo-gravitational movements can be described by both the concept of potential with account of gravitational energy of bodies [Kondratyev, 2003] and the nonlinear physical acoustics [Gurbatov et al., 2008]. Based on the combined description of geophysical and gravitational wave movements, the authors suggest a hypothesis about the nature of spin, i.e. own moment as a demonstration of the space-time ‘vortex’ properties.  

  1. GEODYNAMIC WAVES AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. V. Vikulin

    2014-01-01

    Full Text Available  Gravity phenomena related to the Earth movements in the Solar System and through the Galaxy are reviewed. Such movements are manifested by geological processes on the Earth and correlate with geophysical fields of the Earth. It is concluded that geodynamic processes and the gravity phenomena (including those of cosmic nature are related.  The state of the geomedium composed of blocks is determined by stresses with force moment and by slow rotational waves that are considered as a new type of movements [Vikulin, 2008, 2010]. It is shown that the geomedium has typical rheid properties [Carey, 1954], specifically an ability to flow while being in the solid state [Leonov, 2008]. Within the framework of the rotational model with a symmetric stress tensor, which is developed by the authors [Vikulin, Ivanchin, 1998; Vikulin et al., 2012a, 2013], such movement of the geomedium may explain the energy-saturated state of the geomedium and a possibility of its movements in the form of vortex geological structures [Lee, 1928]. The article discusses the gravity wave detection method based on the concept of interactions between gravity waves and crustal blocks [Braginsky et al., 1985]. It is concluded that gravity waves can be recorded by the proposed technique that detects slow rotational waves. It is shown that geo-gravitational movements can be described by both the concept of potential with account of gravitational energy of bodies [Kondratyev, 2003] and the nonlinear physical acoustics [Gurbatov et al., 2008]. Based on the combined description of geophysical and gravitational wave movements, the authors suggest a hypothesis about the nature of spin, i.e. own moment as a demonstration of the space-time ‘vortex’ properties.  

  2. Dual Waves

    OpenAIRE

    Kallosh, Renata

    1994-01-01

    We study the gravitational waves in the 10-dimensional target space of the superstring theory. Some of these waves have unbroken supersymmetries. They consist of Brinkmann metric and of a 2-form field. Sigma-model duality is applied to such waves. The corresponding solutions we call dual partners of gravitational waves, or dual waves. Some of these dual waves upon Kaluza-Klein dimensional reduction to 4 dimensions become equivalent to the conformo-stationary solutions of axion-dilaton gravity...

  3. Feasibility of laparoscopy for small bowel obstruction

    Directory of Open Access Journals (Sweden)

    De Sol Angelo A

    2009-01-01

    Full Text Available Abstract Background Adherential pathology is the most common cause of small bowel obstruction. Laparoscopy in small bowel obstruction does not have a clear role yet; surely it doesn't always represent only a therapeutic act, but it is always a diagnostic act, which doesn't interfere with abdominal wall integrity. Methods We performed a review without any language restrictions considering international literature indexed from 1980 to 2007 in Medline, Embase and Cochrane Library. We analyzed the reference lists of the key manuscripts. We also added a review based on international non-indexed sources. Results The feasibility of diagnostic laparoscopy is high (60–100%, while that of therapeutic laparoscopy is low (40–88%. The frequency of laparotomic conversions is variable ranging from 0 to 52%, depending on patient selection and surgical skill. The first cause of laparotomic conversion is a difficult exposition and treatment of band adhesions. The incidence of laparotomic conversions is major in patients with anterior peritoneal band adhesions. Other main causes for laparotomic conversion are the presence of bowel necrosis and accidental enterotomies. The predictive factors for successful laparoscopic adhesiolysis are: number of previous laparotomies ≤ 2, non-median previous laparotomy, appendectomy as previous surgical treatment causing adherences, unique band adhesion as phatogenetic mechanism of small bowel obstruction, early laparoscopic management within 24 hours from the onset of symptoms, no signs of peritonitis on physical examination, experience of the surgeon. Conclusion Laparoscopic adhesiolysis in small bowel obstruction is feasible but can be convenient only if performed by skilled surgeons in selected patients. The laparoscopic adhesiolysis for small bowel obstruction is satisfactorily carried out when early indicated in patients with a low number of laparotomies resulting in a short hospital stay and a lower postoperative

  4. 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.)

  5. Reconstruction of constant slow-roll inflation

    Science.gov (United States)

    Gao, Qing

    2017-09-01

    Using the relations between the slow-roll parameters and the power spectra for the single field slow-roll inflation, we derive the scalar spectral tilt n s and the tensor to scalar ratio r for the constant slow-roll inflation, and obtain the constraint on the slow-roll parameter η from the Planck 2015 results. The inflationary potential for the constant slow-roll inflation is then reconstructed in the framework of both general relativity and the scalar-tensor theory of gravity, and compared with the recently reconstructed E model potential. In the strong coupling limit, we show that the η attractor is reached.

  6. Phase of Spontaneous Slow Oscillations during Sleep Influences Memory-Related Processing of Auditory Cues.

    Science.gov (United States)

    Batterink, Laura J; Creery, Jessica D; Paller, Ken A

    2016-01-27

    Slow oscillations during slow-wave sleep (SWS) may facilitate memory consolidation by regulating interactions between hippocampal and cortical networks. Slow oscillations appear as high-amplitude, synchronized EEG activity, corresponding to upstates of neuronal depolarization and downstates of hyperpolarization. Memory reactivations occur spontaneously during SWS, and can also be induced by presenting learning-related cues associated with a prior learning episode during sleep. This technique, targeted memory reactivation (TMR), selectively enhances memory consolidation. Given that memory reactivation is thought to occur preferentially during the slow-oscillation upstate, we hypothesized that TMR stimulation effects would depend on the phase of the slow oscillation. Participants learned arbitrary spatial locations for objects that were each paired with a characteristic sound (eg, cat-meow). Then, during SWS periods of an afternoon nap, one-half of the sounds were presented at low intensity. When object location memory was subsequently tested, recall accuracy was significantly better for those objects cued during sleep. We report here for the first time that this memory benefit was predicted by slow-wave phase at the time of stimulation. For cued objects, location memories were categorized according to amount of forgetting from pre- to post-nap. Conditions of high versus low forgetting corresponded to stimulation timing at different slow-oscillation phases, suggesting that learning-related stimuli were more likely to be processed and trigger memory reactivation when they occurred at the optimal phase of a slow oscillation. These findings provide insight into mechanisms of memory reactivation during sleep, supporting the idea that reactivation is most likely during cortical upstates. Slow-wave sleep (SWS) is characterized by synchronized neural activity alternating between active upstates and quiet downstates. The slow-oscillation upstates are thought to provide a

  7. Resetting Wave Forms in Dictyostelium Territories

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung J.; Goldstein, Raymond E.; Cox, Edward C.

    2001-08-06

    The mechanism by which spiral wave patterns appear in populations of Dictyostelium was probed experimentally by external chemical perturbation. Spiral waves, which often arise from the breakup of circular waves driven by pacemakers, typically entrain those pacemakers. We studied these processes by resetting the waves with a spatially uniform pulse of extrinsic cyclic AMP. A pattern of spirals reappeared if resetting was early in the signaling stage, but only targets emerged following late resetting, in a manner analogous to cardiac defibrillation. This supports recent hypotheses that wave pattern selection naturally occurs by slow temporal variation of the excitability of the cells.

  8. Small bowel diverticulitis with severe anemia and abdominal pain

    Science.gov (United States)

    De Minicis, Samuele; Antonini, Filippo; Belfiori, Valerio; Lo Cascio, Massimiliano; Marraccini, Barbara; Piergallini, Simona; Mosca, Piergiorgio; Macarri, Giampiero

    2015-01-01

    The current case report is related to a male patient with diabetes, obesity [body mass index (BMI) 33], hypertension and recurrence of anemia associated to melena and deep asthenia. M.P., a 60-year-old obese individual, was referred to our department by the primary care unit (PCU) of our hospital for severe anemia (Hemoglobin 6.5 g/dL) associated to episodes of melena and abdominal pain. In the past 5 mo the patient referred to the local hospital 3 times for episodes of melena (hemoglobin levels showed anemia 9.8 g/dL) but the main gastroenterological exams were completely negative (colonoscopy and gastroscopy). The PCU of our Hospital, after stabilization of the main parameters and blood transfusion for the low levels of hemoglobin, referred the patient to gastroenterologists: the patient was subjected to both colonoscopy and gastroscopy that were negative. Due to the condition of acute severe hemorrhage the patient, during the first 3 h from the access to the PCU, was subjected to arteriography that did not reveal any hemorrhagic foci or vascular alterations. The video capsule for the study of the small bowel showed the presence of blood beginning from the third portion of duodenum but deep gastroscopy did not reveal it. The patient was then subjected to double balloon endoscopy that revealed a severe diverticulosis of the small bowel with blood from the diverticula. The entero-tomografia computerizzata confirmed the diagnosis and revealed an extension of the diverticula for almost the entire small bowel (no diverticula in the colon). The patient was subjected to wide spectrum antibiotic therapy with resolution of the symptoms and stabilization of hemoglobin levels. The surgeon suggests no indication to surgery for the wide area involved from the disease and potential high risk of complication due to the high BMI. At home, the patient started a monthly therapy with rifaximin and probiotics associated to mesalazine. At present, after 12 mo from the last episode of

  9. Slow light optofluidics: a proposal.

    Science.gov (United States)

    Sumetsky, M

    2014-10-01

    The resonant slow light structures created along a thin-walled optical capillary by nanoscale deformation of its surface can perform comprehensive simultaneous detection and manipulation of microfluidic components. This concept is illustrated with a model of a 0.5 mm long, 5 nm high, triangular bottle resonator created at a 50 μm radius silica capillary containing floating microparticles. The developed theory shows that the microparticle positions can be determined from the bottle resonator spectrum. In addition, the microparticles can be driven and simultaneously positioned at predetermined locations by the localized electromagnetic field created by the optimized superposition of eigenstates of this resonator, thus exhibiting a multicomponent, near-field optical tweezer.

  10. Incoherent "slow and fast light".

    Science.gov (United States)

    Zapasskii, Valerii; Kozlov, Gleb

    2009-11-23

    We show experimentally that the effects of pulse delay and advancement usually ascribed to the "slow and fast light" under conditions of the coherent population oscillations (CPO) can be universally observed with incoherent light fields on objects with the pure-intensity nonlinearity. As a light source, we used an incandescent lamp and as objects for study, a photochromic glass and a thermochromic coating. The response of the objects to intensity modulation of the incident light reproduced in all details the commonly accepted experimental evidences of the "light with a negative group velocity" and "ultraslow light". Thus we show that observations of the pulse delay (advancement) and characteristic changes in the light intensity modulation spectrum are not enough to make conclusion about modification of the light group velocity in the medium.

  11. 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.

  12. Traditional Procurement is too Slow

    Directory of Open Access Journals (Sweden)

    Ann Kong

    2012-11-01

    Full Text Available This paper reports on an exploratory interview survey of construction project participants aimed at identifying the reasons for the decrease in use of the traditional, lump-sum, procurement system in Malaysia. The results show that most people believe it is too slow. This appears to be in part due to the contiguous nature of the various phase and stages of the process and especially the separation of the design and construction phases. The delays caused by disputes between the various parties are also seen as a contributory factor - the most prominent cause being the frequency of variations, with design and scope changes being a particular source of discontent. It is concluded that an up scaling of the whole of the time related reward/penalty system may be the most appropriate measure for the practice in future.

  13. Slow molecular recognition by RNA.

    Science.gov (United States)

    Gleitsman, Kristin R; Sengupta, Raghuvir N; Herschlag, Daniel

    2017-12-01

    Molecular recognition is central to biological processes, function, and specificity. Proteins associate with ligands with a wide range of association rate constants, with maximal values matching the theoretical limit set by the rate of diffusional collision. As less is known about RNA association, we compiled association rate constants for all RNA/ligand complexes that we could find in the literature. Like proteins, RNAs exhibit a wide range of association rate constants. However, the fastest RNA association rates are considerably slower than those of the fastest protein associations and fall well below the diffusional limit. The apparently general observation of slow association with RNAs has implications for evolution and for modern-day biology. Our compilation highlights a quantitative molecular property that can contribute to biological understanding and underscores our need to develop a deeper physical understanding of molecular recognition events. © 2017 Gleitsman et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  14. Comparison of coupling to 5 GHz lower hybrid waves and 0.5 GHz helicon waves

    Science.gov (United States)

    Pinsker, R. I.; Porkolab, M.; Petty, C. C.; Prater, R.; Moeller, C. P.

    2015-12-01

    We compare, qualitatively and with a simple semi-quantitative model, the difficulty of coupling to fast waves at 0.5 GHz ('whistlers' or 'helicons') and to slow waves ('lower hybrid waves') at 5 GHz and n||=3 under conditions relevant to the DIII-D tokamak. Though the density at which the slow wave begins to propagate is much lower than the fast wave, the stronger evanescence in vacuum for the higher frequency wave makes excitation of the SWs more difficult than for the FW case. Enforcing a minimum density at the coupler face, as might be produced by local gas puffing, is shown to likely be more effective for the SW case. The fact that the surface admittance for the slow wave at 0.5 GHz is much larger than for the FW at the same frequency has possibly significant implications for attempts to excite the FW.

  15. Linear theory of plasma filled backward wave oscillator

    Indian Academy of Sciences (India)

    An analytical and numerical study of backward wave oscillator (BWO) in linear regime is presented to get an insight into the excitation of electromagnetic waves as a result of the interaction of the relativistic electron beam with a slow wave structure. The effect of background plasma on the BWO instability is also presented.

  16. Identifying decreased peristalsis of abnormal small bowel segments in Crohn's disease using cine MR enterography: the frozen bowel sign.

    Science.gov (United States)

    Guglielmo, Flavius F; Mitchell, Donald G; O'Kane, Patrick L; Deshmukh, Sandeep P; Roth, Christopher G; Burach, Ilene; Burns, Aaron; Dulka, Susan; Parker, Laurence

    2015-06-01

    The purpose of this study was to evaluate whether affected bowel in Crohn's disease patients can be identified by observing decreased peristalsis (frozen bowel sign) using cine balanced steady-state free precession (cine BSSFP) images. 5 radiologists independently reviewed cine BSSFP sequences from randomized MR Enterography (MRE) exams for 30 normal and 30 Crohn's disease patients, graded overall small bowel peristalsis from slowest to fastest, and graded peristalsis for the most abnormal small bowel segment. Sensitivity and specificity of the frozen bowel sign for diagnosing Crohn's disease were calculated. T tests of the peristalsis difference between abnormal segments and overall small bowel were conducted. For 5 readers, the sensitivity and specificity of cine BSSFP of the frozen bowel sign for diagnosing Crohn's disease ranged from 70% to 100% and 87% to 100%, respectively. There were significant differences in peristalsis between abnormal small bowel segments and the overall small bowel for Crohn's patients, but not in the overall small bowel between normal-MRE patients and Crohn's disease patients. Abnormal Crohn's small bowel segments have significantly decreased peristalsis compared to normal small bowel, which can be identified using cine BSSFP sequences as the frozen bowel sign.

  17. Fibromyalgia in inflammatory bowel disease.

    Science.gov (United States)

    Buskila, D; Odes, L R; Neumann, L; Odes, H S

    1999-05-01

    Studies of the rheumatological complications of inflammatory bowel disease (IBD; Crohn's disease and ulcerative colitis) have focused on peripheral arthritis and spondylitis, and less is known about soft tissue rheumatism, specifically the fibromyalgia syndrome (FM). Our aim was to estimate the prevalence of FM and assess pain thresholds in patients with Crohn's disease (CD) and ulcerative colitis (UC). Seventy-two patients with UC and 41 with CD attending consecutively at the Gastroenterology Outpatient Clinic were assessed for the presence of FM and tenderness thresholds. FM was diagnosed according to the American College of Rheumatology 1990 criteria. Tenderness was measured by manual palpation and with a dolorimeter. One hundred twenty healthy subjects served as controls. FM was documented in 30 of 113 patients with IBD (30%), specifically in 49% of patients with CD and 19% with UC (p = 0.001); in controls the rate was 0%. Subjects with CD exhibited more tenderness and reported more frequent and more severe FM associated symptoms than subjects with UC. Patients with CD had a higher tender point count, 11.3 (+/- 6.5), than those with UC, 6.4 (+/- 5.7) (p = 0.001); in healthy controls, the count was 0.1 (+/- 0.5). Tenderness thresholds (kg) were lower in CD 2.9 (+/- 1.7) than UC 3.9 (+/- 2.0) (p = 0.005) and controls 5.8 (+/- 0.9). FM is common in IBD, particularly Crohn's disease. The lower pain threshold in Crohn's disease may suggest a disease-specific effect. Recognizing FM in patients with IBD will prevent misdiagnosis and ensure correct treatment.

  18. 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...

  19. 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.

  20. Small Bowel Obstruction caused by a Carcinoid Tumour | Shallaly ...

    African Journals Online (AJOL)

    We present a rare case of carcinoid tumour presenting as a small bowel obstruction in a young male patient. Pitfalls of diagnosis, including confusion with irritable bowel syndrome are high-lighted. The current management strategies of this tumour are reviewed. Keywords: irritable bowel, appendicitis, choleystitis.

  1. 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.

  2. Multidetector CT findings of bowel Transection in blunt abdominal trauma

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyun Suk; Woo, Ji Young; Hong, Hye Suk; Park, Mee Hyun; Yang, Ik; Lee, Yul; Jung, Ah Young; Hwang, Ji Young [Dept. of Radiology, Hallym University College of Medicine, Kangnam Sacred Heart Hospital, Seoul (Korea, Republic of); Ha, Hong Il [Dept. of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Anyang (Korea, Republic of)

    2013-08-15

    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 blunt abdominal trauma. We investigated the incidence of bowel transection in 513 patients admitted for blunt abdominal trauma who underwent multidetector CT (MDCT). The MDCT findings of 8 patients with a surgically proven complete bowel transection were assessed retrospectively. We report novel CT signs that are unique for transection, such as complete cutoff sign (transection of bowel loop), Janus sign (abnormal dual bowel wall enhancement, both increased and decreased), and fecal spillage. The incidence of bowel transection in blunt abdominal trauma was 1.56%. In eight cases of bowel transection, percentage of CT signs unique for bowel transection were as follows: complete cutoff in 8 (100%), Janus sign in 6 (100%, excluding duodenal injury), and fecal spillage in 2 (25%). The combination of complete cutoff and Janus sign were highly specific findings in patients with bowel transection. Complete cut off and Janus sign are the unique CT findings to help detect bowel transection in blunt abdominal trauma and recognition of these findings enables an accurate and prompt diagnosis for emergency laparotomy leading to reduced mortality and morbidity.

  3. 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

  4. Achieving the best bowel preparation for colonoscopy.

    Science.gov (United States)

    Parra-Blanco, Adolfo; Ruiz, Alex; Alvarez-Lobos, Manuel; Amorós, Ana; Gana, Juan Cristóbal; Ibáñez, Patricio; Ono, Akiko; Fujii, Takahiro

    2014-12-21

    Bowel preparation is a core issue in colonoscopy, as it is closely related to the quality of the procedure. Patients often find that bowel preparation is the most unpleasant part of the examination. It is widely accepted that the quality of cleansing must be excellent to facilitate detecting neoplastic lesions. In spite of its importance and potential implications, until recently, bowel preparation has not been the subject of much study. The most commonly used agents are high-volume polyethylene glycol (PEG) electrolyte solution and sodium phosphate. There has been some confusion, even in published meta-analyses, regarding which of the two agents provides better cleansing. It is clear now that both PEG and sodium phosphate are effective when administered with proper timing. Consequently, the timing of administration is recognized as one of the central factors to the quality of cleansing. The bowel preparation agent should be administered, at least in part, a few hours in advance of the colonoscopy. Several low volume agents are available, and either new or modified schedules with PEG that usually improve tolerance. Certain adjuvants can also be used to reduce the volume of PEG, or to improve the efficacy of other agents. Other factors apart from the choice of agent can improve the quality of bowel cleansing. For instance, the effect of diet before colonoscopy has not been completely clarified, but an exclusively liquid diet is probably not required, and a low-fiber diet may be preferable because it improves patient satisfaction and the quality of the procedure. Some patients, such as diabetics and persons with heart or kidney disease, require modified procedures and certain precautions. Bowel preparation for pediatric patients is also reviewed here. In such cases, PEG remains the most commonly used agent. As detecting neoplasia is not the main objective with these patients, less intensive preparation may suffice. Special considerations must be made for patients

  5. Antibiotics during childhood and inflammatory bowel disease?

    Science.gov (United States)

    2014-10-01

    Four epidemiological studies, including two large cohort studies in children aged 17 years or under, have studied the link between antibiotic therapy and inflammatory bowel disease. The risk of inflammatory bowel disease appeared to be twice as high in children exposed to an antibiotic as in unexposed children. The risk appeared higher following exposure during the first year of life, with beta-lactam antibiotics, and with repeated antibiotic courses. One postulated mechanism is through destruction of the anaerobic intestinal flora by antibiotics. In practice, these data provide yet another reason to avoid unnecessarily exposing children to antibiotics.

  6. Caring for Women with Inflammatory Bowel Disease.

    Science.gov (United States)

    Feagins, Linda A; Kane, Sunanda V

    2016-06-01

    Ulcerative colitis and Crohn disease are chronic inflammatory diseases with typical onset in early adulthood. These diseases, therefore, can affect a woman throughout the many stages of her life, including menstruation, sexuality, pregnancy, and menopause. Unique health issues face women during these stages and can affect the course of their inflammatory bowel disease as well as treatment strategies and health maintenance. This article covers the non-pregnancy-related issues that are important in caring for women with inflammatory bowel disease. The topics of pregnancy and fertility are covered in a separate review. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Small bowel imaging - still a radiologic approach?

    Science.gov (United States)

    Markova, Ingrid; Kluchova, Katerina; Zboril, Radek; Mashlan, Miroslav; Herman, Miroslav

    2010-06-01

    In recent years, there has been renewed interest in small bowel imaging using a variety of radiologic or endoscopic techniques. This article gives an overview and comparison of old and new techniques used in small bowel imaging. New imaging methods as computed tomography (CT), CT enteroclysis (CTEc), CT enterography (CTEg), ultrasound (US), contrast-enhanced ultrasound (CEUS), US enteroclysis, US enterography, magnetic resonance imaging (MRI), MR enteroclysis (MREc) and MR enterography (MREg) are compared with the older techniques such as small- bowel follow- through (SBFT), conventional enteroclysis (CE) and endoscopic techniques including push enteroscopy, ezofagogastroduodenoscopy (EGD), sonde enteroscopy, ileocolonoscopy, double-balloon enteroscopy, intraoperative enteroscopy and wireless capsule enteroscopy (WCE). Systematic scan of Pubmed, Medline, Ovid, Elsevier search engines was used.. Additional information was found through the bibliographical review of relevant articles. SBFT has only secondary role in small bowel imaging. US is still the method of choice in imaging for pediatric populations. US and CEUS are also accepted as a method of choice especially in inflammatory cases. CE has been replaced by new cross - sectional imaging techniques (CTEc/CTEg or MREc/MREg). CTEc combines the advantages of CT and CE. MREc combines the advantages of MRI and CE. Some authors prefer CTEg or MREg with peroral bowel preparation and they strictly avoid nasojejunal intubation under fluoroscopic control. MREc has better soft tissue contrast, showing it to be more sensitive in detecting mucosal lesions than CTEc in inflammatory diseases. CTEg/MREg are techniques preferred for patients in follow-up of the inflammatory diseases. The radiologic community is not unanimous however about their role in the imaging process. CTEc/MREc as well as CTEg/MREg are superior to endoscopic methods in the investigation of small-bowel tumors. WCE gives unparalleled imaging of the mucosal

  8. Large-scale dynamic triggering of shallow slow slip enhanced by overlying sedimentary wedge

    Science.gov (United States)

    Wallace, Laura M.; Kaneko, Yoshihiro; Hreinsdóttir, Sigrún; Hamling, Ian; Peng, Zhigang; Bartlow, Noel; D'Anastasio, Elisabetta; Fry, Bill

    2017-10-01

    Slow slip events have become recognized in the last decade as an important mode of fault slip, and are most widely observed at subduction zones. Many episodes of tectonic tremor (related to slow slip) have been triggered by distant earthquakes due to dynamic-stress changes from passing seismic waves. However, there are few clear examples of large, geodetically detected slow slip events triggered by distant earthquakes. Here we use analyses of seismic and geodetic data to show that the magnitude 7.8 Kaikōura earthquake in New Zealand in 2016 triggered a large slow slip event between 250 and 600 km away. The slow slip was shallow, at less than 15 km deep, and spanned more than 15,000 km2 of the central and northern Hikurangi subduction margin. The slow slip initiated immediately after the earthquake, lasted one to two weeks and was accompanied by a swarm of seismicity. We show that changes in dynamic stress in the slow slip source area ranged from 100 to 600 kPa--approximately 1,000 times greater than the static-stress changes of 0.2 to 0.7 kPa. We therefore propose that the slow slip event was triggered by dynamic-stress changes caused by passing seismic waves. Furthermore, the dynamic-stress changes were greatest on the shallow subduction interface, at less than 10 km depth, in a region overlain by a sedimentary wedge that acts as a waveguide, trapping seismic energy and probably promoting triggering of slip. This suggests that shallow slow slip events are more easily triggered by dynamic-stress changes compared with deep events.

  9. Theoretical analysis and experiment performance of slow-light based on stimulated Brillouin scattering (SBS)

    Science.gov (United States)

    Zhou, Hongyan; Zhong, Kun; Zhang, Ru; Lang, Peilin

    2011-02-01

    Slow light technology will play a key role in future all-optical communication. The slow-light technology based on stimulated Brillouin scattering has become a research highlight because of its additional advantages, such as compatibility of the devices with existing telecommunication systems, room-temperature operation, and tunable at arbitrary wavelengths. According to the propagation of a cw pulse through a Brillouin fiber amplifier, whose frequency is near the Stokes resonance, via three-wave coupling equations, both pump depletion and fiber losses taken into consideration, the principle of how slow-light effect based on stimulated Brillouin scattering produced and the mathematical expression of time delay are strictly deduced. A delay of 8 ns is obtained when the input Stokes pulse is 200ns and the SBS (stimulated Brillouin scattering) gain G is ~18 in our designed experiment of SBS slow-light system. Then the extent of transformation from pump waves to Stokes waves is measured using MATLAB numerical simulation according to the experiment dates, based on the relation between output pump light power and input pump light power and also the relation between output Stokes light power and input pump light power. And the relation between the input light power and propagation distance is discussed as well. Finally the relation between slow light pulse delay and SBS gain is also obtained.

  10. Slow light engineering in photonic crystals

    OpenAIRE

    Baba, Toshihiko; Mori, Daisuke

    2007-01-01

    Light showing extremely slow propagation (known as slow light) provides various effects such as spatial compression of optical signals, buffering, convolution integral calculation, beam forming, and enhancement of optical absorption, gain, nonlinearity, and so on. To generate such light, very large material or structural dispersion is used. Photonic crystal waveguides are good candidates for many device applications since they can easily generate slow light at room temperature. This paper dis...

  11. Applications of Slow Light in Telecommunications

    National Research Council Canada - National Science Library

    Boyd, Robert W; Gauthier, Daniel J; Gaeta, Alexander L

    2006-01-01

    .... Now, optical scientists are turning their attention toward developing useful applications of slow light, including controllable optical delay lines, optical buffers and true time delay methods...

  12. Emergence of slow collective oscillations in neural networks with spike-timing dependent plasticity

    DEFF Research Database (Denmark)

    Mikkelsen, Kaare; Imparato, Alberto; Torcini, Alessandro

    2013-01-01

    The collective dynamics of excitatory pulse coupled neurons with spike timing dependent plasticity (STDP) is studied. The introduction of STDP induces persistent irregular oscillations between strongly and weakly synchronized states, reminiscent of brain activity during slow-wave sleep. We explain...

  13. Modal theory of slow light enhanced third-order nonlinear effects in photonic crystal waveguides.

    Science.gov (United States)

    Chen, Tao; Sun, Junqiang; Li, Linsen

    2012-08-27

    In this paper, we derive the couple-mode equations for third-order nonlinear effects in photonic crystal waveguides by employing the modal theory. These nonlinear interactions include self-phase modulation, cross-phase modulation and degenerate four-wave mixing. The equations similar to that in nonlinear fiber optics could be expanded and applied for third-order nonlinear processes in other periodic waveguides. Based on the equations, we systematically analyze the group-velocity dispersion, optical propagation loss, effective interaction area, slow light enhanced factor and phase mismatch for a slow light engineered silicon photonic crystal waveguide. Considering the two-photon and free-carrier absorptions, the wavelength conversion efficiencies in two low-dispersion regions are numerically simulated by utilizing finite difference method. Finally, we investigate the influence of slow light enhanced multiple four-wave-mixing process on the conversion efficiency.

  14. Fast and slow thermal processes in harmonic scalar lattices

    Science.gov (United States)

    Kuzkin, V. A.; Krivtsov, A. M.

    2017-12-01

    An approach for analytical description of thermal processes in harmonic lattices is presented. We cover longitudinal and transverse vibrations of chains and out-of-plane vibrations of two-dimensional lattices with interactions of an arbitrary number of neighbors. The motion of each particle is governed by a single scalar equation and therefore the notion ‘scalar lattice’ is used. The evolution of initial temperature field in an infinite lattice is investigated. An exact equation describing the evolution is derived. Continualization of this equation with respect to spatial coordinates is carried out. The resulting continuum equation is solved analytically. The solution shows that the kinetic temperature is represented as the sum of two terms, one describing short time behavior, the other large time behavior. At short times, the temperature performs high-frequency oscillations caused by redistribution of energy among kinetic and potential forms (fast process). Characteristic time of this process is of the order of ten periods of atomic vibrations. At large times, changes of the temperature are caused by ballistic heat transfer (slow process). The temperature field is represented as a superposition of waves having the shape of initial temperature distribution and propagating with group velocities dependent on the wave vector. Expressions describing fast and slow processes are invariant with respect to substitution t by -t . However, examples considered in the paper demonstrate that these processes are irreversible. Numerical simulations show that presented theory describes the evolution of temperature field at short and large time scales with high accuracy.

  15. Slow Activity in Focal Epilepsy During Sleep and Wakefulness.

    Science.gov (United States)

    Pellegrino, Giovanni; Tombini, Mario; Curcio, Giuseppe; Campana, Chiara; Di Pino, Giovanni; Assenza, Giovanni; Tomasevic, Leo; Di Lazzaro, Vincenzo

    2017-05-01

    We aimed to test differences between healthy subjects and patients with respect to slow wave activity during wakefulness and sleep. Fifteen patients affected by nonlesional focal epilepsy originating within temporal areas and fourteen matched controls underwent a 24-hour EEG recording. We studied the EEG power spectral density during wakefulness and sleep in delta (1-4 Hz), theta (5-7 Hz), alpha (8-11 Hz), sigma (12-15 Hz), and beta (16-20 Hz) bands. During sleep, patients with focal epilepsy showed higher power from delta to beta frequency bands compared with controls. The effect was widespread for alpha band and above, while localized over the affected hemisphere for delta (sleep cycle 1, P = .006; sleep cycle 2, P = .008; sleep cycle 3, P = .017). The analysis of interhemispheric differences showed that the only frequency band stronger over the affected regions was the delta band during the first 2 sleep cycles (sleep cycle 1, P = .014; sleep cycle 2, P = .002). During wakefulness, patients showed higher delta/theta activity over the affected regions compared with controls. Patients with focal epilepsy showed a pattern of power increases characterized by a selective slow wave activity enhancement over the epileptic regions during daytime and sleep. This phenomenon was stronger and asymmetric during the first sleep cycles.

  16. Slow earthquakes and low frequency tremor along the Apennines, Italy

    Directory of Open Access Journals (Sweden)

    F. Tronca

    2008-06-01

    Full Text Available This paper reviews the main observations on slow earthquakes and low frequency tremor made along the Apennines, the main seismic active zone of Italy. These observations have been made using a geodetic interferometer system operating since 1994 in the underground tunnel of Gran Sasso, central Italy, and an underground seismic array (UNDERSEIS operating since 2002 in the same environment. The observations made in recent years indicate that both phenomena are quite rare and apparently uncorrelated. Slow earthquakes, mainly recorded in 1997 and occasionally later, have probably been caused by the activity of a shallow fault system located near the interferometers. Until now only one tremor episode characterized by low frequency content and duration of several hours has been detected in January 2004, without any correlations with the occurrence of slow or regular earthquakes. The signal to noise ratio of this event is very low, but the results of our detailed analysis show that its frequency contents and wave field characteristics are compatible with a low frequency non volcanic tremor.

  17. Gender differences in inflammatory bowel disease: Explaining body image dissatisfaction.

    Science.gov (United States)

    Trindade, Inês A; Ferreira, Cláudia; Duarte, Cristiana; Pinto-Gouveia, José

    2017-12-01

    The aim of this study was to examine the role of body image problems in the context of inflammatory bowel disease and to explore gender differences in these associations. A sample of inflammatory bowel disease patients (60 males and 140 females) was collected. Findings from a multi-group analysis show that inflammatory bowel disease symptomatology may impact on body image in both male and female patients through the effect of body-image-related cognitive fusion. Body image difficulties in the context of inflammatory bowel disease should not be a neglected dimension in research aiming at understanding the psychosocial effects of inflammatory bowel disease and by health professionals working with these patients.

  18. 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.

  19. Sustained eye closure slows saccades

    Science.gov (United States)

    Shaikh, Aasef G.; Wong, Aaron L.; Optican, Lance M.; Miura, Kenichiro; Solomon, David; Zee, David S.

    2010-01-01

    Saccadic eye movements rapidly orient the line of sight towards the object of interest. Pre-motor burst neurons (BNs) controlling saccades receive excitation from superior colliculus and cerebellum, but inhibition by omnipause neurons (OPNs) prevents saccades. When the OPNs pause, BNs begin to fire. It has been presumed that part of the BN burst comes from post-inhibitory rebound (PIR). We hypothesized that in the absence of prior inhibition from OPNs there would be no PIR, and thus the increase in initial firing rate of BNs would be reduced. Consequently, saccade acceleration would be reduced. We measured eye movements and showed that sustained eye closure, which inhibits the activity of OPNs and thus hypothetically should weaken PIR, reduced the peak velocity, acceleration, and deceleration of saccades in healthy human subjects. Saccades under closed eyelids also had irregular trajectories; the frequency of the oscillations underlying this irregularity was similar to that of high-frequency ocular flutter (back-to-back saccades) often seen in normal subjects during attempted fixation at straight ahead while eyes are closed. Saccades and quick phases of nystagmus are generated by the same pre-motor neurons, and we found that the quick-phase velocity of nystagmus was also reduced by lid closure. These changes were not due to a mechanical hindrance to the eyes, because lid closure did not affect the peak velocities or accelerations of the eyes in the “slow-phase” response to rapid head movements of comparable speeds to those of saccades. These results indicate a role for OPNs in generating the abrupt onset and high velocities of saccades. We hypothesize that the mechanism involved is PIR in pre-motor burst neurons. PMID:20573593

  20. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  1. Methods for diagnosing irritable bowel syndrome

    NARCIS (Netherlands)

    Tuk, L.; Vos, de W.M.; Rajilic-Stojanovic, M.

    2015-01-01

    The present invention discloses a method for diagnosing Irritable Bowel Syndrome (IBS) in a test sample by determining the level of several bacterial taxa in the test sample, comparing this level with the levels of those bacterial taxa in a control sample, and relating the level to a diagnosis of

  2. Methods for diagnosing irritable bowel syndrome

    NARCIS (Netherlands)

    Tuk, L.; Vos, de W.M.; Rajilic-Stojanovic, M.

    2012-01-01

    The present invention discloses a method for diagnosing Irritable Bowel Syndrome (IBS) in a test sample by determining the level of several bacterial taxa in the test sample, comparing this level with the levels of those bacterial taxa in a control sample, and relating the level to a diagnosis of

  3. Isotretinoin-induced inflammatory bowel disease

    NARCIS (Netherlands)

    Passier, J L M; Srivastava, N; van Puijenbroek, E P

    Three case reports on inflammatory bowel disease associated with use of isotretinoin are described. All three patients were male adolescents, in good health when starting isotretinoin (for acne treatment for about six months). Several weeks after discontinuation of isotretinoin the patients

  4. Adult Bochdalek hernia with bowel incarceration.

    Science.gov (United States)

    Hung, Yeh-Huang; Chien, Yu-Hon; Yan, Sheng-Lei; Chen, Ming-Feng

    2008-10-01

    Bochdalek hernias are rare in adults. We report 2 cases of Bochdalek hernia with bowel obstruction. The first case was a 74-year-old male patient who suffered from abdominal pain and chest tightness for 1 day. Chest radiography indicated a mass-like lesion above the left diaphragm. The pain could not be relieved by nasogastric tube decompression for 12 hours. We arranged computed tomography, which revealed a dilated bowel above the diaphragm and intestinal obstruction with gangrenous change. The patient received emergency laparotomy, and a Bochdalek hernia was detected during the operation. The second case was a 75-year-old female patient who suffered from chest tightness and dyspnea for about 1 week. Chest X-ray and magnetic resonance imaging revealed herniation of small and large bowels at the right posterior aspect of the thoracic cavity. She received transthoracic repair of diaphragmatic hernia, recovered, and was discharged 15 days later. We recommend that adult Bochdalek hernia should be considered in the differential diagnosis of bowel obstruction.

  5. Adult Bochdalek Hernia with Bowel Incarceration

    Directory of Open Access Journals (Sweden)

    Yeh-Huang Hung

    2008-10-01

    Full Text Available Bochdalek hernias are rare in adults. We report 2 cases of Bochdalek hernia with bowel obstruction. The first case was a 74-year-old male patient who suffered from abdominal pain and chest tightness for 1 day. Chest radiography indicated a mass-like lesion above the left diaphragm. The pain could not be relieved by nasogastric tube decompression for 12 hours. We arranged computed tomography, which revealed a dilated bowel above the diaphragm and intestinal obstruction with gangrenous change. The patient received emergency laparotomy, and a Bochdalek hernia was detected during the operation. The second case was a 75-year-old female patient who suffered from chest tightness and dyspnea for about 1 week. Chest X-ray and magnetic resonance imaging revealed herniation of small and large bowels at the right posterior aspect of the thoracic cavity. She received transthoracic repair of diaphragmatic hernia, recovered, and was discharged 15 days later. We recommend that adult Bochdalek hernia should be considered in the differential diagnosis of bowel obstruction.

  6. Preoperative bowel preparation in children: Polyethylene glycol ...

    African Journals Online (AJOL)

    Background: Colorectal surgeries frequently require bowel preparation. In children, (is this standard of care?: this method is mostly followed) this is usually performed using normal saline, which is very cumbersome and causes unnecessary discomfort. This study compared polyethylene glycol (PEG) with normal saline for ...

  7. 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

  8. Bowel injury following gynecological laparoscopic surgery.

    African Journals Online (AJOL)

    When bowel injury is recognized during the first laparoscopic procedure then laparoscopic primary suturing could be tried although laparotomy may be needed. When diagnosis is delayed, then laparotomy is the treatment of choice. The role of robotic surgery and three-dimensional laparoscopic gynecological surgery on ...

  9. Future directions in inflammatory bowel disease management

    NARCIS (Netherlands)

    D'Haens, Geert R.; Sartor, R. Balfour; Silverberg, Mark S.; Petersson, Joel; Rutgeerts, Paul

    2014-01-01

    Clinical management of inflammatory bowel diseases (IBD), new treatment modalities and the potential impact of personalised medicine remain topics of intense interest as our understanding of the pathophysiology of IBD expands. Potential future strategies for IBD management are discussed, based on

  10. Anatomy and Physiology of the Small Bowel.

    Science.gov (United States)

    Volk, Neil; Lacy, Brian

    2017-01-01

    Comprehension of small intestine physiology and function provides a framework for the understanding of several important disease pathways of the gastrointestinal system. This article reviews the development, anatomy and histology of the small bowel in addition to physiology and digestion of key nutrients. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Inflammatory bowel disease with primary sclerosing cholangitis

    DEFF Research Database (Denmark)

    Sørensen, Jakob Ørskov; Nielsen, Ole Haagen; Andersson, Mikael

    2017-01-01

    BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) may be complicated by primary sclerosing cholangitis (PSC). We aimed to assess the characteristics of Danish PSC-IBD patients and to compare their prognosis with IBD patients without PSC. METHODS: A retrospective nationwide population...

  12. Innate lymphoid cells in inflammatory bowel diseases

    NARCIS (Netherlands)

    Peters, C. P.; Mjösberg, J. M.; Bernink, J. H.; Spits, H.

    2016-01-01

    It is generally believed that inflammatory bowel diseases (IBD) are caused by an aberrant immune response to environmental triggers in genetically susceptible individuals. The exact contribution of the adaptive and innate immune system has not been elucidated. However, recent advances in treatments

  13. The epidemiology of irritable bowel syndrome

    DEFF Research Database (Denmark)

    Krogsgaard, L. R.; Engsbro, A. L.; Jones, M. P.

    2017-01-01

    Background: We aimed to explore the natural history of irritable bowel syndrome (IBS) in Denmark over 3 years by studying development of IBS symptoms and associated factors. Methods: A cohort study was carried out using a web panel representative of the Danish general population 18-50 years...

  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. Familial risk of inflammatory bowel disease

    DEFF Research Database (Denmark)

    Moller, Frederik Trier; Andersen, Vibeke; Wohlfahrt, Jan

    2015-01-01

    OBJECTIVES: Estimates of familial risk of inflammatory bowel diseases (IBDs), Crohn's disease (CD), and ulcerative colitis (UC) are needed for counseling of patients and could be used to target future prevention. We aimed to provide comprehensive population-based estimates of familial risk of IBD...

  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

  17. 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...

  18. Bowel injury following gynecological laparoscopic surgery.

    African Journals Online (AJOL)

    High clinical suspicion is crucial for early diagnosis. Diagnostic workup of suspected cases includes serial ab- dominal examination, measuring inflammatory markers, and performing imaging studies including abdominal ultrasound and. CT scan. When bowel injury is recognized during the first laparoscopic procedure then ...

  19. Dynamic bowel obstruction: aetiology, clinical presentation ...

    African Journals Online (AJOL)

    Data were analyzed using SPSS software system. A total of .... This was a descriptive prospective study of patients operated for dynamic bowel obstruction at Bugando ... The modal age group was 31-40 years accounting for 32.2% of cases (Table 1). Two hundred and six (60.2%) patients were aged 40 years and below.

  20. 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...