Sample records for ve tidal volume

  1. Tidal breathing flow-volume loops in bronchiolitis in infancy: the effect of albuterol [ISRCTN47364493]. (United States)

    Totapally, Balagangadhar R; Demerci, Cem; Zureikat, George; Nolan, Brian


    To evaluate the effect of nebulized albuterol on tidal breathing flow-volume loops in infants with bronchiolitis due to respiratory syncytial virus. A randomized, double-blind, control study. Pediatric unit in a community teaching hospital. Twenty infants younger than 1 year of age (mean age, 5.8 +/- 2.8 months) with a first episode of wheezing due to respiratory syncytial virus bronchiolitis. Chloral hydrate (50 mg/kg) was administered orally for sedation. One dose each of nebulized albuterol (0.15 mg/kg in 3 ml saline) and saline (3 ml) were given at 6 hour intervals in a random order. Tidal breathing flow-volume loops were obtained before and after each aerosol treatment with a Neonatal/Pediatric Pulmonary Testing System (Model 2600; Sensor Medics, Anaheim, CA, USA). At the same time, the fraction of tidal volume exhaled at peak tidal expiratory flow (PTEF) to total tidal volume (VPTEF/VE), and the fraction of exhaled time at PTEF to total expiratory time (tPTEF/tE) were measured. The PTEF, the tidal expiratory flows at 10%, 25%, and 50% of the remaining tidal volume (TEF10, TEF25, and TEF50), and the wheeze score were also determined. There were no significant changes in VPTEF/VE and tPTEF/tE after albuterol or saline treatment. PTEF increased significantly both after albuterol and saline treatments but the difference between the two treatments was not significant (P = 0.6). Both TEF10 and the ratio of the tidal expiratory flow at 25% of the remaining tidal volume to PTEF (25/PT) decreased significantly (P bronchiolitis due to respiratory syncytial virus did not improve VPTEF/VE and tPTEF/tE but did decrease TEF10 and 25/PT.

  2. High tidal volume ventilation in infant mice. (United States)

    Cannizzaro, Vincenzo; Zosky, Graeme R; Hantos, Zoltán; Turner, Debra J; Sly, Peter D


    Infant mice were ventilated with either high tidal volume (V(T)) with zero end-expiratory pressure (HVZ), high V(T) with positive end-expiratory pressure (PEEP) (HVP), or low V(T) with PEEP. Thoracic gas volume (TGV) was determined plethysmographically and low-frequency forced oscillations were used to measure the input impedance of the respiratory system. Inflammatory cells, total protein, and cytokines in bronchoalveolar lavage fluid (BALF) and interleukin-6 (IL-6) in serum were measured as markers of pulmonary and systemic inflammatory response, respectively. Coefficients of tissue damping and tissue elastance increased in all ventilated mice, with the largest rise seen in the HVZ group where TGV rapidly decreased. BALF protein levels increased in the HVP group, whereas serum IL-6 rose in the HVZ group. PEEP keeps the lungs open, but provides high volumes to the entire lungs and induces lung injury. Compared to studies in adult and non-neonatal rodents, infant mice demonstrate a different response to similar ventilation strategies underscoring the need for age-specific animal models.

  3. Tidal volume and alveolar clearance of insoluble particles. (United States)

    John, J; Wollmer, P; Dahlbäck, M; Luts, A; Jonson, B


    We studied the effect of 3 h of large tidal volume ventilation on alveolar clearance of 0.63-micron fluorescent latex particles in rabbits during pentobarbital anesthesia. After particle deposition, six animals were killed as controls, six were subjected to large tidal volume ventilation with a peak pressure of 27 cmH2O, and six were subjected to conventional ventilation with a peak pressure of 11 cmH2O. Mean tidal volumes were 30.2 +/- 6.1 and 8.4 +/- 1.6 ml/kg in the large tidal volume and conventional groups, respectively. End-expiratory pressure was 2 cmH2O in all groups. Compliance decreased only after large tidal ventilation (P = 0.0036). Compared with controls the conventional ventilation group showed no alveolar clearance, but more particles were clustered within macrophages (P = 0.01). Compared with other groups the large tidal volume group had fewer alveolar particles (P = 0.0005), most of which were single particles. Accordingly, large tidal volumes enhance alveolar particle clearance, which is possibly related to distension-related evacuation of surfactant to proximal airways. Clearance may be due to accelerated motion of the particle-loaded macrophage in response to the fast film motion. Alternatively, single particles embedded in the surfactant film may be dragged by the fast-moving film toward the airways.

  4. The Changes in Pulse Pressure Variation or Stroke Volume Variation After a "Tidal Volume Challenge" Reliably Predict Fluid Responsiveness During Low Tidal Volume Ventilation. (United States)

    Myatra, Sheila Nainan; Prabu, Natesh R; Divatia, Jigeeshu Vasishtha; Monnet, Xavier; Kulkarni, Atul Prabhakar; Teboul, Jean-Louis


    Stroke volume variation and pulse pressure variation do not reliably predict fluid responsiveness during low tidal volume ventilation. We hypothesized that with transient increase in tidal volume from 6 to 8 mL/kg predicted body weight, that is, "tidal volume challenge," the changes in pulse pressure variation and stroke volume variation will predict fluid responsiveness. Prospective, single-arm study. Medical-surgical ICU in a university hospital. Adult patients with acute circulatory failure, having continuous cardiac output monitoring, and receiving controlled low tidal volume ventilation. The pulse pressure variation, stroke volume variation, and cardiac index were recorded at tidal volume 6 mL/kg predicted body weight and 1 minute after the "tidal volume challenge." The tidal volume was reduced back to 6 mL/kg predicted body weight, and a fluid bolus was given to identify fluid responders (increase in cardiac index > 15%). The end-expiratory occlusion test was performed at tidal volumes 6 and 8 mL/kg predicted body weight and after reducing tidal volume back to 6 mL/kg predicted body weight. Thirty measurements were obtained in 20 patients. The absolute change in pulse pressure variation and stroke volume variation after increasing tidal volume from 6 to 8 mL/kg predicted body weight predicted fluid responsiveness with areas under the receiver operating characteristic curves (with 95% CIs) being 0.99 (0.98-1.00) and 0.97 (0.92-1.00), respectively. The best cutoff values of the absolute change in pulse pressure variation and stroke volume variation after increasing tidal volume from 6 to 8 mL/kg predicted body weight were 3.5% and 2.5%, respectively. The pulse pressure variation, stroke volume variation, central venous pressure, and end-expiratory occlusion test obtained during tidal volume 6 mL/kg predicted body weight did not predict fluid responsiveness. The changes in pulse pressure variation or stroke volume variation obtained by

  5. Do new anesthesia ventilators deliver small tidal volumes accurately during volume-controlled ventilation? (United States)

    Bachiller, Patricia R; McDonough, Joseph M; Feldman, Jeffrey M


    During mechanical ventilation of infants and neonates, small changes in tidal volume may lead to hypo- or hyperventilation, barotrauma, or volutrauma. Partly because breathing circuit compliance and fresh gas flow affect tidal volume delivery by traditional anesthesia ventilators in volume-controlled ventilation (VCV) mode, pressure-controlled ventilation (PCV) using a circle breathing system has become a common approach to minimizing the risk of mechanical ventilation for small patients, although delivered tidal volume is not assured during PCV. A new generation of anesthesia machine ventilators addresses the problems of VCV by adjusting for fresh gas flow and for the compliance of the breathing circuit. In this study, we evaluated the accuracy of new anesthesia ventilators to deliver small tidal volumes. Four anesthesia ventilator systems were evaluated to determine the accuracy of volume delivery to the airway during VCV at tidal volume settings of 100, 200, and 500 mL under different conditions of breathing circuit compliance (fully extended and fully contracted circuits) and lung compliance. A mechanical test lung (adult and infant) was used to simulate lung compliances ranging from 0.0025 to 0.03 L/cm H(2)O. Volumes and pressures were measured using a calibrated screen pneumotachograph and custom software. We tested the Smartvent 7900, Avance, and Aisys anesthesia ventilator systems (GE Healthcare, Madison, WI) and the Apollo anesthesia ventilator (Draeger Medical, Telford, PA). The Smartvent 7900 and Avance ventilators use inspiratory flow sensors to control the volume delivered, whereas the Aisys and Apollo ventilators compensate for the compliance of the circuit. We found that the anesthesia ventilators that use compliance compensation (Aisys and Apollo) accurately delivered both large and small tidal volumes to the airway of the test lung under conditions of normal and low lung compliance during VCV (ranging from 95.5% to 106.2% of the set tidal volume

  6. Ventilation with lower tidal volumes as compared to conventional tidal volumes for patients without acute lung injury - a preventive randomized controlled trial

    NARCIS (Netherlands)

    Determann, Rogier M.; Royakkers, Annick; Wolthuis, Esther K.; Vlaar, Alexander P.; Choi, Goda; Paulus, Frederique; Hofstra, Jorrit-Jan; de Graaff, Mart J.; Korevaar, Johanna C.; Schultz, Marcus J.


    ABSTRACT: INTRODUCTION: Recent cohort studies have identified use of large tidal volumes as a major risk factor for development of lung injury in mechanically ventilated patients without acute lung injury (ALI). We compared the effect of conventional versus lower tidal volumes on pulmonary

  7. Ventilation with lower tidal volumes as compared with conventional tidal volumes for patients without acute lung injury: a preventive randomized controlled trial.

    NARCIS (Netherlands)

    Determann, R.M.; Royakkers, A.; Wolthuis, E.K.; Vlaar, A.P.; Choi, G.; Paulus, F.; Hofstra, J.J.; Graaff, M.J. de; Korevaar, J.C.; Schultz, M.J.


    Introduction: Recent cohort studies have identified the use of large tidal volumes as a major risk factor for development of lung injury in mechanically ventilated patients without acute lung injury (ALI). We compared the effect of conventional with lower tidal volumes on pulmonary inflammation and

  8. Ventilation with lower tidal volumes as compared with conventional tidal volumes for patients without acute lung injury : a preventive randomized controlled trial

    NARCIS (Netherlands)

    Determann, Rogier M; Royakkers, Annick; Wolthuis, Esther K; Vlaar, Alexander P; Choi, Goda; Paulus, Frederique; Hofstra, Jorrit-Jan; de Graaff, Mart J; Korevaar, Johanna C; Schultz, Marcus J


    INTRODUCTION: Recent cohort studies have identified the use of large tidal volumes as a major risk factor for development of lung injury in mechanically ventilated patients without acute lung injury (ALI). We compared the effect of conventional with lower tidal volumes on pulmonary inflammation and

  9. Targeted minute ventilation and tidal volume in an animal model of acute changes in lung mechanics and episodes of hypoxemia. (United States)

    Claure, Nelson; Suguihara, Cleide; Peng, Jinghong; Hehre, Dorothy; D'Ugard, Carmen; Bancalari, Eduardo


    Acute episodes of hypoxemia in ventilated preterm infants are triggered by changes in ventilation, lung volume (LV) and respiratory system compliance (C(RS)) that are not prevented by conventional synchronized intermittent mandatory ventilation (SIMV). To assess in a rabbit model of episodic hypoxemia the individual and combined efficacy of targeted tidal volume (V(T)) and minute ventilation (V'(E)) by automatic adjustment of peak inspiratory pressure (PIP) and ventilator rate, respectively. Six young New Zealand white rabbits were ventilated with SIMV, targeted V(T), targeted V'(E), and combined targeted V'(E) + V(T) in random sequence. Hypoxemia episodes were induced by apnea alone or by apnea combined with a reduction in LV and C(RS). Apnea was induced by a bolus of propofol. The reduction in LV and C(RS) was induced by chest compression with a cuff. PaO(2) and PaCO(2) were measured continuously by an indwelling arterial electrode. During SIMV, apnea caused a decrease in ventilation and PaO(2). This was attenuated during targeted V'(E) and targeted V'(E) + V(T). Apnea plus a reduction in LV and C(RS) caused a greater decrease in ventilation and PaO(2) during SIMV. These changes were attenuated during targeted V(T) and targeted V'(E). The attenuation was more pronounced during targeted V'(E) + V(T). In this animal model, targeted V'(E) was effective in reducing hypoxemia caused by apnea. When apnea was accompanied by a reduction in LV and C(RS), the combined adjustment of PIP and ventilator rate was more effective than each individually. This combined strategy may be effective in ameliorating acute episodes of hypoxemia in preterm infants but this remains to be proven.

  10. Tidal volume delivery during surfactant administration in the delivery room. (United States)

    Schmölzer, Georg M; Kamlin, C Omar F; Dawson, Jennifer A; Morley, Colin J; Davis, Peter G


    Reduced mortality for infants born at less than 30 weeks’ gestation after prophylactic surfactant administration has led many to advocate routine intubation and administration of surfactant in all infants at risk of respiratory distress syndrome. However, surfactant administration is associated with adverse events including bradycardia, changes in cerebral blood flow and endotracheal tube obstruction. The aim of this study was to analyse respiratory function immediately before and after surfactant administration in the delivery room. We reviewed video recordings of the initial resuscitation in the delivery room of infants born at less than 32 weeks’ gestation between February 2007 and March 2010. Positive pressure ventilation was delivered with either a Neopuff T-piece or self-inflating bag. Respiratory parameters were recorded with a respiratory function monitor (RFM). Each RFM recording was analysed for 30 s before and 2 min after surfactant administration. Of 230 infants recorded during the study period 16 infants received surfactant in the delivery room. Their mean (standard deviation, SD) gestation and birth weight were 25 (1) weeks and 757 (249) g, respectively. Complete airway obstruction was seen in 4/16 (25%) infants. The median (interquartile range, IQR) duration of this obstruction was 16 (8–27) s. The median (IQR) expired tidal volume before surfactant delivery was 8.0 (5.2–11.2) mL/kg compared to 4.6 (4.1–7.3) mL/kg (p = 0.03) after surfactant administration. Substantial tidal volume changes occur before, during and after surfactant administration in the delivery room. Complete airway obstruction is common. Monitoring respiratory function during this procedure may help to assess the delivered tidal volume and airway pressures after surfactant treatment.

  11. Normalization of respiratory sinus arrhythmia by factoring in tidal volume. (United States)

    Kobayashi, H


    The amplitude of respiratory sinus arrhythmia (RSA) was measured in eight healthy young male students with special reference to the effect of tidal volume (Vt). Under simultaneously controlled respiratory frequency and Vt, the heart rate variability (HRV) of the subjects was measured. While the respiratory frequency was adjusted to either 0.25 or 0.10 Hz, the Vt was controlled at 13 different volumes for each frequency. Linear relationships between RSA amplitude and Vt were observed and close correlations were obtained for 0.25 Hz compared with 0.10 Hz. However, regression equations showed a marked variation among subjects. Furthermore, RSA amplitude was related to vital capacity. Subjects who had lower vital capacity tended to show higher RSA amplitudes at the same Vt. Therefore, the ratio (% Vt) of Vt to vital capacity is a more effective index in normalizing RSA than raw tidal volume. From these results, we have proposed a normalized RSA (RSA amplitude/% Vt) as a new index of autonomic activity that provides a constant value regardless of Vt.

  12. Low Tidal Volume Reduces Lung Inflammation Induced by Liquid Ventilation in Piglets With Severe Lung Injury. (United States)

    Jiang, Lijun; Feng, Huizhen; Chen, Xiaofan; Liang, Kaifeng; Ni, Chengyao


    Total liquid ventilation (TLV) is an alternative treatment for severe lung injury. High tidal volume is usually required for TLV to maintain adequate CO2 clearance. However, high tidal volume may cause alveolar barotrauma. We aim to investigate the effect of low tidal volume on pulmonary inflammation in piglets with lung injury and under TLV. After the establishment of acute lung injury model by infusing lipopolysaccharide, 12 piglets were randomly divided into two groups, TLV with high tidal volume (25 mL/kg) or with low tidal volume (6 mL/kg) for 240 min, respectively. Extracorporeal CO2 removal was applied in low tidal volume group to improve CO2 clearance and in high tidal volume group as sham control. Gas exchange and hemodynamic status were monitored every 30 min during TLV. At the end of the study, pulmonary mRNA expression and plasmatic concentration of interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured by collecting lung tissue and blood samples from piglets. Arterial blood pressure, PaO2 , and PaCO2 showed no remarkable difference between groups during the observation period. Compared with high tidal volume strategy, low tidal volume resulted in 76% reduction of minute volume and over 80% reduction in peak inspiratory pressure during TLV. In addition, low tidal volume significantly diminished pulmonary mRNA expression and plasmatic level of IL-6 and IL-8. We conclude that during TLV, low tidal volume reduces lung inflammation in piglets with acute lung injury without compromising gas exchange. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  13. Effects of gas composition on the delivered tidal volume of the Avance Carestation. (United States)

    Miyaji, Tetsuya; Fukakura, Yoshimasa; Usuda, Yutaka; Maruyama, Koichi; Hirabayashi, Go; Yamada, Rieko; Akihisa, Yuki; Nishioka, Hiroko; Andoh, Tomio


    Measurements with various flowmeters are affected by changes in gas mixture density. The Avance Carestation incorporates ventilator feedback controlled by a built-in flowmeter with a variable orifice sensor. We hypothesised that changes in the composition of delivered gas may cause changes in the delivered tidal volume by affecting the flow measurement unless appropriate corrections are made. We used 100 % O2, 40 % O2 in N2 and 40 % O2 in N2O as carrier gases with/without sevoflurane and desflurane. We measured delivered tidal volume using the FlowAnalyzer™ PF 300 calibrated with the corresponding gas mixtures during volume control ventilation with 500-ml tidal volume using the Avance Carestation connected to a test lung. Change of carrier gas and addition of sevoflurane and desflurane significantly altered delivered tidal volume. Desflurane 6 % reduced delivered tidal volume by 7.6, 3.6 and 16 % of the pre-set volume at 100 % O2, 40 % O2 in N2 and 40 % O2 in N2O, respectively. Importantly, the Carestation panel indicator did not register these changes in measured expired tidal volume. Ratios of delivered tidal volume to 500 ml correlated inversely with the square root of the delivered gas density. These results support our hypothesis and suggest that changing gas composition may alter delivered tidal volume of anesthesia machines with built-in ventilators that are feedback-controlled by uncorrected flowmeters due to changes in gas mixture density.

  14. Effect of tidal volume and respiratory rate on the power of breathing calculation. (United States)

    Natalini, G; Marchesini, M; Tessadrelli, A; Rosano, A; Candiani, A; Bernardini, A


    The power of breathing (PoB) is used to estimate the mechanical workload of the respiratory system. Aim of this study was to investigate the effect of different tidal volume-respiratory rate combinations on the PoB when the elastic load is constant. In order to assure strict control of the experimental conditions, the PoB was calculated on an airway pressure-volume curve in mechanically ventilated patients. Ten patients received three different tidal volume-respiratory rate combinations while minute ventilation was constant. Respiratory mechanics, PoB and its elastic and resistive components were calculated. Alternative methods to estimate the elastic workload were assessed: elastic work of breathing per litre per minute, elastic workload index (the square root of elastic work of breathing multiplied by respiratory rate) and elastic double product of the respiratory system (the elastic pressure multiplied by respiratory rate). Despite constant elastance and minute ventilation, the elastic PoB showed an increment greater than 200% from the lower to the greater tidal volume, accounting for approximately 80% of the whole PoB increment. On the contrary, elastic work of breathing per litre per minute, elastic workload index and elastic double product did not change. Changes in breathing pattern markedly affect the PoB despite constant mechanical load. Other indexes could assess the elastic workload without tidal volume dependence. Power of breathing use should be avoided to compare different mechanical loads or efficiencies of the respiratory muscles when tidal volume is variable.

  15. Pharmacodynamic modeling of propofol-induced tidal volume depression in children. (United States)

    Hahn, Jin-Oh; Khosravi, Sara; Dosani, Maryam; Dumont, Guy A; Mark Ansermino, J


    This investigation aimed to develop a pediatric pharmacodynamic model of propofol-induced tidal volume depression towards an ultimate goal of developing a dosing schedule that would preserve spontaneous breathing following a loading dose of propofol. Fifty two ASA 1 and 2 children aged 6-15 year presenting for gastrointestinal endoscopy were enrolled. Subjects were administered a loading dose of 4 mg/kg of propofol intravenously at a constant infusion rate determined by a randomization schedule. Respiratory parameters including tidal volume, respiratory rate, minute volume, and end-tidal CO(2) were recorded at 5 s intervals. Using the predicted plasma concentration, based on the Paedfusor pharmacokinetic model, propofol-induced tidal volume depression was modeled by 3 different approaches (2-stage, pooled, and mixed effects) and results were compared using prediction residual, median percentage errors, median absolute percentage errors, and root-mean-squared normalized errors. The effects of age and body weight as covariates were examined. Respiratory rate and end-tidal CO(2) did not show clear dependence on the predicted plasma concentration. The pharmacodynamic models for tidal volume derived from different modeling approaches were highly consistent. The 2-stage, pooled, and mixed effects approaches yielded k(e0) of 1.06, 1.24, and 0.72 min(-1); γ of 1.10, 0.83, and 0.93; EC50 of 3.18, 3.44, and 3.00 mcg/ml. Including age and body weight as covariates did not significantly improve the predictive performance of the models. A pediatric pharmacodynamic model of propofol-induced tidal volume depression was developed. Models derived from 3 different approaches were shown to be consistent with each other; however, the individual pharmacodynamic parameters exhibited significant inter-individual variability without strong dependence on age and body weight. This would suggest the desirability of adapting the pharmacodynamic model to each subject in real time.

  16. Intraoperative low tidal volume ventilation strategy has no benefits during laparoscopic cholecystectomy

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    Vandna Arora


    Conclusion: Strategy using 6 ml/kg tidal volume along with 10 cmH2O of PEEP was not associated with any significant improvement in gas exchange, hemodynamic parameters, or systemic inflammatory response over ventilation with 10 ml/kg volume without PEEP during laparoscopic cholecystectomy.

  17. Mechanical ventilation with high tidal volume and associated mortality in the cardiac intensive care unit. (United States)

    Shorofsky, Matthew; Jayaraman, Dev; Lellouche, Francois; Husa, Regina; Lipes, Jed


    Use of protective ventilation has been shown to decrease mortality in medical-surgical ICUs. There is limited data on tidal volume use in ventilated patients in the cardiac intensive care unit (CICU). We hypothesized that large tidal volumes are used in the CICU and that they could contribute to an increase in morbidity and mortality. We conducted a retrospective chart review of all mechanically ventilated patients with congestive heart failure or cardiac arrest in a single tertiary care CICU between April 2010 and February 2012. Ventilator settings were analyzed and tidal volume for predicted body weight (VT/PBW) was calculated for 51 patients. The median initial tidal volume was 525 ml (IQR: 500-600) and median VT/PBW was 9.3 ml/kg (IQR: 8.3-10.1). Overall mortality was 29.4%. On univariate analysis, patients that received a VT/PBW below the median, mortality was 23.1% (95% CI: 7.9-39.3) compared to 36.0% (95% CI: 17.2-55.0) in patients that received a VT/PBW above themedian (P = 0.31). On multivariate analysis, the OR for death was 9.0 (95% CI: 1.3-62.0, P = 0.03) with VT/PBW above the median. Mechanical ventilation with high tidal volumes was associated with increased mortality in patients with congestive heart failure and post cardiac arrest in our CICU.

  18. Tidal volume in acute respiratory distress syndrome: how best to select it. (United States)

    Umbrello, Michele; Marino, Antonella; Chiumello, Davide


    Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

  19. The Effect of Low Tidal Volume Ventilation during Cardiopulmonary Bypass on Postoperative Pulmonary Function

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    Gholamreza Safarpour


    Full Text Available Background: Postoperative pulmonary dysfunction is one of the most frequent complications after cardiac surgery and it is believed to result from the use of cardiopulmonary bypass (CPB. In this study, we investigated the effect of low tidal volume ventilation during CPB on postoperative gas exchange and lung mechanics.Methods: This prospective randomized study included 100 patients undergoing elective coronary artery bypass grafting. In 50 patients, low tidal volume ventilation [tidal volume (TV = 3 ml/kg, respiratory rate (RR = 12/min, fraction of inspiratory oxygen (FIO2= 1.0, positive end expiratory pressure (PEEP = 5 cmH2O] was applied during CPB (group I; and in the other 50 patients (group II, the lungs were open to the atmosphere without ventilation. Measurements were taken preoperatively,after CPB, and before discharge.Results: Post-bypass PaO2 (just after CPB 85 versus75 was higher significantly in group I (P value < 0.05. Decrease in postoperative forced expiratory volume in 1 second (25% versus 30% and forced vital capacity (32% versus 35% was less significant in group I. Also, time to extubation (5 hrs versus 5.5 hrs was shorter in group I.Conclusion: Continued low tidal volume ventilation during CPB improved post-bypass oxygenation and lung mechanics.

  20. Effects of tidal volume and PEEP on arterial blood gases and pulmonary mechanics during one-lung ventilation. (United States)

    Kim, Sang Hun; Jung, Ki Tae; An, Tae Hun


    The main problem of one-lung ventilation (OLV) is hypoxemia. The use of a high tidal volume for preventing hypoxemia during OLV is controversial. We compared the effects of a high tidal volume versus a low tidal volume with or without PEEP on arterial oxygen tension (PaO(2)) and pulmonary mechanics during OLV. Sixty patients (age range, 16-65 years; ASA I, II) who underwent wedge resection with video-assisted thoracostomy during OLV were assigned to three groups: group I received a high tidal volume (10 ml/kg) (n = 20), group II received a low tidal volume (6 ml/kg) (n = 20), and group III received a low tidal volume (6 ml/kg) with PEEP (5 cmH(2)O) (n = 20). Patient hemodynamics, pulmonary mechanics, and arterial blood gases were measured before (T(0)) OLV and 5 (T(1)), 15 (T(2)), 30 (T(3)), and 45 min (T(4)) after OLV. The PaO(2)/FiO(2) ratios of group II and III were significantly decreased and the incidence of hypoxemia was significantly higher in groups II and III than in group I (P mechanical ventilation with a low tidal volume with or without PEEP increased hypoxemia as compared to that when performing OLV with a high tidal volume.

  1. Effects of inhalational anaesthesia with low tidal volume ventilation on end-tidal sevoflurane and carbon dioxide concentrations: prospective randomized study. (United States)

    de la Matta-Martín, M; López-Herrera, D; Luis-Navarro, J C; López-Romero, J L


    We investigated how ventilation with low tidal volumes affects the pharmacokinetics of sevoflurane uptake during the first minutes of inhaled anaesthesia. Forty-eight patients scheduled for lung resection were randomly assigned to three groups. Patients in group 1, 2 and 3 received 3% sevoflurane for 3 min via face mask and controlled ventilation with a tidal volume of 2.2, 8 and 12 ml kg(-1), respectively (Phase 1). After tracheal intubation (Phase 2), 3% sevoflurane was supplied for 2 min using a tidal volume of 8 ml kg(-1) (Phase 3). End-tidal sevoflurane concentrations were significantly higher in group 1 at the end of phase 1 and lower at the end of phase 2 than in the other groups as follows: median of 2.5%, 2.2% and 2.3% in phase 1 for groups 1, 2 and 3, respectively (P<0.001); and 1.7%, 2.1% and 2.0% in phase 2, respectively (P<0.001). End-tidal carbon dioxide values in group 1 were significantly lower at the end of phase 1 and higher at the end of phase 2 than in the other groups as follows: median of 16.5, 31 and 29.5 mm Hg in phase 1 for groups 1, 2 and 3, respectively (P<0.001); and 46.2, 36 and 33.5 mm Hg in phase 2, respectively (P<0.001). When sevoflurane is administered with tidal volume approximating the airway dead space volume, end-tidal sevoflurane and end-tidal carbon dioxide may not correctly reflect the concentration of these gases in the alveoli, leading to misinterpretation of expired gas data. Copyright © 2013 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

  2. The impact of large tidal volume ventilation on the absorption of inhaled insulin in rabbits

    DEFF Research Database (Denmark)

    Petersen, Astrid Heide; Laursen, Torben; Ahrén, Bo


    Previous studies have shown that ventilation patterns affect absorption of inhaled compounds. Thus, the aim of this study was to investigate the effect of large tidal volume ventilation (LTVV) on the absorption of inhaled insulin in rabbits. Mechanically ventilated rabbits were given human insuli...

  3. Effects of mechanical ventilation with different tidal volume on oxidative stress and antioxidant in lung. (United States)

    Sun, Zhen-Tao; Yang, Chun-Yao; Miao, Li-Jun; Zhang, Shan-Feng; Han, Xue-Ping; Ren, Su-En; Sun, Xue-Qing; Cao, Ya-Nan


    The aim of this study was to investigate the changes in oxidative stress and antioxidants in lung tissue under different tidal volume ventilation conditions. Forty-eight male Wistar rats were randomized into four groups, namely, group C, the control group, which was not ventilated, and groups C1, C2 and C3, the treatment groups, which were ventilated for 2 h with tidal volumes of 8, 30 and 42 ml/kg, respectively. The right middle lobe was assayed for malondialdehyde (MDA), the right posterior lobe was assayed using Western blotting for Nrf2, GCLm and SrX1 and the left lobe was assayed for Nrf2, GCLm and SrX1 mRNA. The MDA levels were increased in the three treatment groups, with MDA levels highest in group C3 and lowest in group C1 (C3 > C2 > C1) (all P C2 > C1) (all P 0.05). A Western blot analysis showed that Nrf2, GCLm and SrX1 expression was highest in group C3 and lowest in group C1 (C3 > C2 > C1) (all P 0.05). Oxidative stress and antioxidant enzyme levels in the lungs of rats were positively associated with the tidal volumes of mechanical ventilation, suggesting that higher tidal volumes cause more severe oxidative stress and increased antioxidant responses.

  4. Intraoperative ventilation: incidence and risk factors for receiving large tidal volumes during general anesthesia

    Directory of Open Access Journals (Sweden)

    Fernandez-Bustamante Ana


    Full Text Available Abstract Background There is a growing concern of the potential injurious role of ventilatory over-distention in patients without lung injury. No formal guidelines exist for intraoperative ventilation settings, but the use of tidal volumes (VT under 10 mL/kg predicted body weight (PBW has been recommended in healthy patients. We explored the incidence and risk factors for receiving large tidal volumes (VT > 10 mL/kg PBW. Methods We performed a cross-sectional analysis of our prospectively collected perioperative electronic database for current intraoperative ventilation practices and risk factors for receiving large tidal volumes (VT > 10 mL/kg PBW. We included all adults undergoing prolonged (≥ 4 h elective abdominal surgery and collected demographic, preoperative (comorbidities, intraoperative (i.e. ventilatory settings, fluid administration and postoperative (outcomes information. We compared patients receiving exhaled tidal volumes > 10 mL/kg PBW with those that received 8-10 or Results Ventilatory settings were non-uniform in the 429 adults included in the analysis. 17.5% of all patients received VT > 10 mL/kg PBW. 34.0% of all obese patients (body mass index, BMI, ≥ 30, 51% of all patients with a height T > 10 mL/kg PBW. Conclusions Ventilation with VT > 10 mL/kg PBW is still common, although poor correlation with PBW suggests it may be unintentional. BMI ≥ 30, female gender and height

  5. High-Frequency Percussive Ventilation: Pneumotachograph Validation and Tidal Volume Analysis (United States)


    percussive ventilation (HFPV) is an increasingly used mode of mechanical ventilation , for which there is no proven real-time means of measuring delivered... mechanical ventilation ; tidal volume; VT; pneumotachography. [Respir Care 2010;55(6):734–740] Introduction Clinical application of high-frequency percussive...conventional mechanical ventilation (Fig. 1). How- ever, neither the low-frequency nor the high-frequency volumes administered by HFPV are measured by the

  6. Quantitative prediction of respiratory tidal volume based on the external torso volume change: a potential volumetric surrogate

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    Li Guang; Arora, Naveen C; Xie Huchen; Ning, Holly; Citrin, Deborah; Kaushal, Aradhana; Zach, Leor; Camphausen, Kevin; Miller, Robert W [Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Lu Wei; Low, Daniel [Department of Radiation Oncology, Washington University School of Medicine, St Louis, MO 63110 (United States)], E-mail:


    An external respiratory surrogate that not only highly correlates with but also quantitatively predicts internal tidal volume should be useful in guiding four-dimensional computed tomography (4DCT), as well as 4D radiation therapy (4DRT). A volumetric surrogate should have advantages over external fiducial point(s) for monitoring respiration-induced motion of the torso, which deforms in synchronization with a patient-specific breathing pattern. This study establishes a linear relationship between the external torso volume change (TVC) and lung air volume change (AVC) by validating a proposed volume conservation hypothesis (TVC = AVC) throughout the respiratory cycle using 4DCT and spirometry. Fourteen patients' torso 4DCT images and corresponding spirometric tidal volumes were acquired to examine this hypothesis. The 4DCT images were acquired using dual surrogates in cine mode and amplitude-based binning in 12 respiratory stages, minimizing residual motion artifacts. Torso and lung volumes were calculated using threshold-based segmentation algorithms and volume changes were calculated relative to the full-exhalation stage. The TVC and AVC, as functions of respiratory stages, were compared, showing a high correlation (r = 0.992 {+-} 0.005, p < 0.0001) as well as a linear relationship (slope = 1.027 {+-} 0.061, R{sup 2} = 0.980) without phase shift. The AVC was also compared to the spirometric tidal volumes, showing a similar linearity (slope = 1.030 {+-} 0.092, R{sup 2} = 0.947). In contrast, the thoracic and abdominal heights measured from 4DCT showed relatively low correlation (0.28 {+-} 0.44 and 0.82 {+-} 0.30, respectively) and location-dependent phase shifts. This novel approach establishes the foundation for developing an external volumetric respiratory surrogate.

  7. Low tidal volume ventilation preconditioning ameliorates lipopolysaccharide-induced acute lung injury in rats. (United States)

    Zhang, Y; Gao, J; Wang, C-J; Zhou, L-J; Fang, X-Z; Yang, L-Q


    Effects of low tidal volume (LTV) ventilation preconditioning in endotoxin-induced acute lung injury (ALI) have not been studied. We investigated the effect of LTV ventilation pre-treatment on ALI induced by lipopolysaccharide (LPS) in rats. Male Sprague-Dawley rats were assigned to four groups (n = 8 each): (1) sham rats injected (i.p.) with 0.9% (physiologic) saline; sham rats pre-treated with tidal volume 6 ml/kg ventilation for 1 h followed by injection (i.p.) of physiologic saline (mechanical ventilation; MV-saline group); (2) LPS group (rats injected with LPS (i.p.); rats pre-treated with tidal volume 6 ml/kg ventilation for 1 h before injection (i.p.) with LPS (MV-LPS group). Animals were observed for 6 h. ALI extent was evaluated by lung wet-to-dry ratio, Evans Blue Dye extravasation, and histologic examination. We measured levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Apoptotic index (AI) and the expression of pulmonary RhoA, ROCK2 mRNA, and ROCK1 protein in lung alveolar cells was determined. Lipopolysaccharide caused severe ALI, as evidenced by increases in ALI extent, impairment of pulmonary functions, and increases in pulmonary levels of TNF-α, IL-1β, IL-6, and AI. LTV ventilation preconditioning mitigated LPS-induced increases in release of pulmonary pro-inflammatory cytokines and AI of alveolar cells. Expression of pulmonary RhoA, ROCK2 mRNA, and ROCK1 protein was upregulated by LPS and reduced by LTV ventilation pre-treatment. Low tidal volume ventilation preconditioning can attenuate release of pulmonary pro-inflammatory cytokines and decrease the AI induced by severe sepsis. Early protection seems to be mediated partly through inhibition of activation of a Rho pathway. © 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  8. Morphodynamic relationships for ebb and flood delta volumes at Florida's tidal entrances (United States)

    Powell, Mark A.; Thieke, Robert J.; Mehta, Ashish J.


    Tidal entrances constitute an important boundary condition for the coastal ocean regime. Based on data from 67 sandy entrances in Florida, morphodynamic relationships between tidal prism, entrance throat area, and ebb and flood delta volumes are revisited. The main source of sand in these deltas is the littoral zone as opposed to the river. It is found that, as a rule of thumb, the volume of a mature ebb delta is equal to one fifth of the prism at the spring range of tide. Data for the coasts of Florida taken together indicate that the volume of mature flood delta varies with one third power of the prism. The Atlantic Coast flood delta volumes by themselves do not show any correlation with the prism, presumably because entrance depths have been altered by dredging. A case study of the closure of a land barrier breach at Matanzas Inlet illustrates the application of the derived morphodynamic relationships between prism, throat area, and ebb delta volume. These relationships are useful for prediction of changes in the throat area and the ebb delta volume when morphologic changes occur over time scales consistent with the reestablishment of equilibrium.

  9. Assessment of tidal volume and thoracoabdominal motion using volume and flow-oriented incentive spirometers in healthy subjects

    Directory of Open Access Journals (Sweden)

    V.F. Parreira


    Full Text Available The objective of the present study was to evaluate incentive spirometers using volume- (Coach and Voldyne and flow-oriented (Triflo II and Respirex devices. Sixteen healthy subjects, 24 ± 4 years, 62 ± 12 kg, were studied. Respiratory variables were obtained by respiratory inductive plethysmography, with subjects in a semi-reclined position (45º. Tidal volume, respiratory frequency, minute ventilation, inspiratory duty cycle, mean inspiratory flow, and thoracoabdominal motion were measured. Statistical analysis was performed with Kolmogorov-Smirnov test, t-test and ANOVA. Comparison between the Coach and Voldyne devices showed that larger values of tidal volume (1035 ± 268 vs 947 ± 268 ml, P = 0.02 and minute ventilation (9.07 ± 3.61 vs 7.49 ± 2.58 l/min, P = 0.01 were reached with Voldyne, whereas no significant differences in respiratory frequency were observed (7.85 ± 1.24 vs 8.57 ± 1.89 bpm. Comparison between flow-oriented devices showed larger values of inspiratory duty cycle and lower mean inspiratory flow with Triflo II (0.35 ± 0.05 vs 0.32 ± 0.05 ml/s, P = 0.00, and 531 ± 137 vs 606 ± 167 ml/s, P = 0.00, respectively. Abdominal motion was larger (P < 0.05 during the use of volume-oriented devices compared to flow-oriented devices (52 ± 11% for Coach and 50 ± 9% for Voldyne; 43 ± 13% for Triflo II and 44 ± 14% for Respirex. We observed that significantly higher tidal volume associated with low respiratory frequency was reached with Voldyne, and that there was a larger abdominal displacement with volume-oriented devices.

  10. Tidal volume single-breath washin of SF6 and CH4 in transient microgravity (United States)

    Dutrieue, Brigitte; Paiva, Manuel; Verbanck, Sylvia; Le Gouic, Marine; Darquenne, Chantal; Prisk, G. Kim


    We performed tidal volume single-breath washins (SBW) by using tracers of different diffusivity and varied the time spent in microgravity (microG) before the start of the tests to look for time-dependent effects. SF(6) and CH(4) phase III slopes decreased by 35 and 26%, respectively, in microG compared with 1 G (P volumes near functional residual capacity. In previous studies using SF(6) and He (Lauzon A-M, Prisk GK, Elliott AR, Verbanck S, Paiva M, and West JB. J Appl Physiol 82: 859-865, 1997), the vital capacity SBW showed an increase in slope difference between gases in transient microG, the opposite of the decrease in sustained microG. In contrast, tidal volume SBW showed a decrease in slope difference in both microG conditions. Because it is only the behavior of the more diffusive gas that differed between maneuvers and microG conditions, we speculate that, in the previous vital capacity SBW, the hypergravity period preceding the test in transient microG provoked conformational changes at low lung volumes near the acinar entrance.

  11. Effect of tidal volume, sampling duration, and cardiac contractility on pulse pressure and stroke volume variation during positive-pressure ventilation. (United States)

    Kim, Hyung Kook; Pinsky, Michael R


    Both pulse pressure variation and stroke volume variation during intermittent positive-pressure ventilation predict preload responsiveness. However, because ventilatory and cardiac frequencies are not the same, increasing the number of breaths sampled may increase calculated pulse pressure variation and stroke volume variation because larger (max) and smaller (min) pulse pressure and stroke volume may occur. Tidal volume and contractility may also alter pulse pressure variation and stroke volume variation. We hypothesized that the magnitude of pulse pressure variation would increase with sampling duration, and that both tidal volume and contractility would independently alter pulse pressure variation and stroke volume variation. In seven pentobarbital-anesthetized intact dogs arterial and left ventricular pressure (Millar) and left ventricular volume (Leycom) were measured over 8 intermittent positive-pressure ventilation breaths at tidal volume of 5, 10, 15, and 20 mL/kg (f = 20/min, 40% inspiratory time) under baseline, esmolol (2 mg/min), dobutamine infusions (5 microg/kg/min) and following volume loading (500 mL NaCl). Stroke volume variation was calculated using pulse contour method (PiCCO, Pulsion Medical Systems, Munich, Germany) averaged over 12 secs. Pulse pressure variation was calculated as 100 x (PPmax - PPmin)/PPmean and calculated over 1, 2, 3, 4, 5, 6, 7, or 8 breaths. Pulse pressure variation increased progressively with increasing sampling duration up to but not exceeding five breaths. The effect on sampling duration was increased by greater tidal volume. Esmolol infusion decreased both pulse pressure variation and stroke volume variation as compared with baseline (p variation or stroke volume variation. Sampling duration, tidal volume, and beta-adrenergic blockade differentially alters pulse pressure variation and stroke volume variation during intermittent positive-pressure ventilation. Thus, separate validation is required to define threshold

  12. Clinical correlates of hippocampus volume and shape in antipsychotic-naïve schizophrenia. (United States)

    Kalmady, Sunil Vasu; Shivakumar, Venkataram; Arasappa, Rashmi; Subramaniam, Aditi; Gautham, S; Venkatasubramanian, Ganesan; Gangadhar, Bangalore N


    While volume deficit of hippocampus is an established finding in schizophrenia, very few studies have examined large sample of patients without the confounding effect of antipsychotic treatment. Concurrent evaluation of hippocampus shape will offer additional information on the hippocampal aberrations in schizophrenia. In this study, we analyzed the volume and shape of hippocampus in antipsychotic-naïve schizophrenia patients (N=71) in comparison to healthy controls (N=82). Using 3-T MRI data, gray matter (GM) volume (anterior and posterior sub-divisions) and shape of the hippocampus were analyzed. Schizophrenia patients had significant hippocampal GM volume deficits (specifically the anterior sub-division) in comparison to healthy controls. There were significant positive correlations between anterior hippocampus volume and psychopathology scores of positive syndrome. Shape analyses revealed significant inward deformation of bilateral hippocampal surface in patients. In conclusion, our study findings add robust support for volume deficit in hippocampus in antipsychotic-naïve schizophrenia. Hippocampal shape deficits in schizophrenia observed in this study map to anterior CA1 sub-region. The differential relationship of anterior hippocampus (but not posterior hippocampus) with clinical symptoms is in tune with the findings in animal models. Further systematic studies are needed to evaluate the relationship between these hippocampal gray matter deficits with white matter and functional connectivity to facilitate understanding the hippocampal network abnormalities in schizophrenia. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  13. Manual ventilation devices in neonatal resuscitation: tidal volume and positive pressure-provision. (United States)

    Roehr, Charles C; Kelm, Marcus; Fischer, Hendrik S; Bührer, Christoph; Schmalisch, Gerd; Proquitté, Hans


    Excessive peak inspiratory pressures (PIP) and high tidal volumes (Vt) during manual ventilation can be detrimental to the neonatal lung. We compared the influence of different manual ventilation devices and individual professional experience on the extent of applied Vt and PIP in simulated neonatal resuscitation. One hundred and twenty medical professionals were studied. An intubated mannequin (equivalent to 1.0 kg neonate) was ventilated using two different devices: a self-inflating bag and a T-piece resuscitator. Target value was a PIP of 20 cm H(2)O. Applied PIP and the resulting Vt were recorded continuously using a respiratory function monitor (CO(2)SMO(+), Novametrix, USA). Vt and PIP provision was significantly higher in SI-bags, compared to T-piece devices: median (interquartile range) PIP 25.6 (18.2) cm H(2)O vs 19.7 (3.2) cm H(2)O (pbags, compared to T-piece devices. Professional experience had no significant impact on the level and the variability of Vt or PIP provided. Use of T-piece devices guarantees reliable and constant Vt and PIP provision, irrespective of individual, operator dependent variables. Methods to measure and to avoid excessive tidal volumes in neonatal resuscitation need to be developed. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  14. Utilizing Forced Vital Capacity to Predict Low Lung Compliance and Select Intraoperative Tidal Volume During Thoracic Surgery. (United States)

    Hoftman, Nir; Eikermann, Eric; Shin, John; Buckley, Jack; Navab, Kaveh; Abtin, Fereidoun; Grogan, Tristan; Cannesson, Maxime; Mahajan, Aman


    Tidal volume selection during mechanical ventilation utilizes dogmatic formulas that only consider a patient's predicted body weight (PBW). In this study, we investigate whether forced vital capacity (FVC) (1) correlates better to total lung capacity (TLC) than PBW, (2) predicts low pulmonary compliance, and (3) provides an alternative method for tidal volume selection. One hundred thirty thoracic surgery patients had their preoperative TLC calculated via 2 methods: (1) pulmonary function test (PFT; TLCPFT) and (2) computed tomography 3D reconstruction (TLCCT). We compared the correlation between TLC and PBW with the correlation between TLC and FVC to determine which was stronger. Dynamic pulmonary compliance was then calculated from intraoperative ventilator data and logistic regression models constructed to determine which clinical measure best predicted low compliance. Ratios of tidal volume/FVC plotted against peak inspiratory pressure were utilized to construct a new model for tidal volume selection. Calculated tidal volumes generated by this model were then compared with those generated by the standard lung-protective formula Vt = 7 cc/kg. The correlation between FVC and TLC (0.82 for TLCPFT and 0.76 for TLCCT) was stronger than the correlation between PBW and TLC (0.65 for TLCPFT and 0.58 for TLCCT). Patients with very low compliance had significantly smaller lung volumes (forced expiratory volume at 1 second, FVC, TLC) and lower diffusion capacity of the lungs for carbon monoxide when compared with patients with normal compliance. An FVC cutoff of 3470 cc was 100% sensitive and 51% specific for predicting low compliance. The proposed equation Vt = FVC/8 significantly reduced calculated tidal volume by a mean of 22.5% in patients with low pulmonary compliance without affecting the mean tidal volume in patients with normal compliance (mean difference 0.9%). FVC is more strongly correlated to TLC than PBW and a cutoff of about 3.5 L can be utilized to predict

  15. Noninvasive Measurement of Carbon Dioxide during One-Lung Ventilation with Low Tidal Volume for Two Hours: End-Tidal versus Transcutaneous Techniques. (United States)

    Zhang, Hong; Wang, Dong-Xin


    There may be significant difference between measurement of end-tidal carbon dioxide partial pressure (PetCO2) and arterial carbon dioxide partial pressure (PaCO2) during one-lung ventilation with low tidal volume for thoracic surgeries. Transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring can be used continuously to evaluate PaCO2 in a noninvasive fashion. In this study, we compared the accuracy between PetCO2 and PtcCO2 in predicting PaCO2 during prolonged one-lung ventilation with low tidal volume for thoracic surgeries. Eighteen adult patients who underwent thoracic surgeries with one-lung ventilation longer than two hours were included in this study. Their PetCO2, PtcCO2, and PaCO2 values were collected at five time points before and during one-lung ventilation. Agreement among measures was evaluated by Bland-Altman analysis. Ninety sample sets were obtained. The bias and precision when PtcCO2 and PaCO2 were compared were 4.1 ± 6.5 mmHg during two-lung ventilation and 2.9 ± 6.1 mmHg during one-lung ventilation. Those when PetCO2 and PaCO2 were compared were -11.8 ± 6.4 mmHg during two-lung ventilation and -11.8 ± 4.9 mmHg during one-lung ventilation. The differences between PtcCO2 and PaCO2 were significantly lower than those between PetCO2 and PaCO2 at all five time-points (p lung ventilation with low tidal volume for patients undergoing thoracic surgeries.

  16. Differential control of respiratory frequency and tidal volume during high-intensity interval training. (United States)

    Nicolò, Andrea; Marcora, Samuele M; Bazzucchi, Ilenia; Sacchetti, Massimo


    What is the central question of this study? By manipulating recovery intensity and exercise duration during high-intensity interval training (HIIT), we tested the hypothesis that fast inputs contribute more than metabolic stimuli to respiratory frequency (fR ) regulation. What is the main finding and its importance? Respiratory frequency, but not tidal volume, responded rapidly and in proportion to changes in workload during HIIT, and was dissociated from some markers of metabolic stimuli in response to both experimental manipulations, suggesting that fast inputs contribute more than metabolic stimuli to fR regulation. Differentiating between fR and tidal volume may help to unravel the mechanisms underlying exercise hyperpnoea. Given that respiratory frequency (fR ) has been proposed as a good marker of physical effort, furthering the understanding of how fR is regulated during exercise is of great importance. We manipulated recovery intensity and exercise duration during high-intensity interval training (HIIT) to test the hypothesis that fast inputs (including central command) contribute more than metabolic stimuli to fR regulation. Seven male cyclists performed an incremental test, a 10 and a 20 min continuous time trial (TT) as preliminary tests. Subsequently, recovery intensity and exercise duration were manipulated during HIIT (30 s work and 30 s active recovery) by performing four 10 min and one 20 min trial (recovery intensities of 85, 70, 55 and 30% of the 10 min TT mean workload; and 85% of the 20 min TT mean workload). The work intensity of the HIIT sessions was self-paced by participants to achieve the best performance possible. When manipulating recovery intensity, fR , but not tidal volume (VT ), showed a fast response to the alternation of the work and recovery phases, proportional to the extent of workload variations. No association between fR and gas exchange responses was observed. When manipulating exercise duration, fR and rating of

  17. Pulmonary hemodynamic and tidal volume changes during exercise in heart failure. (United States)

    Agostoni, Piergiuseppe; Guazzi, Marco; Doria, Elisabetta; Marenzi, Giancarlo


    Impairment of lung mechanics, increase of pulmonary artery pressure and limitation of exercise capacity are common findings in chronic heart failure. The objective of the present study was to evaluate whether pulmonary mechanics are correlated with pulmonary hemodynamics, whether both are correlated with the functional capacity and whether the time course of their changes during exercise correlates with the exercise capacity. We performed a cardiopulmonary exercise test (breath by breath analysis of ventilation and gas exchange, cycloergometer, 25 W increments every 3 min) with pulmonary hemodynamic monitoring in 38 heart failure patients. The parameters were analyzed at rest, 1 min after the work rate increase and at peak exercise. A significant linear correlation with peak oxygen consumption was found at rest for: mean pulmonary artery pressure (mPAP, r = -0.56), right atrial pressure (RAP, r = -0.42), pulmonary wedge pressure (PWP, r = -0.53), and total pulmonary (TPR, r = -0.53) and pulmonary vascular resistances (PVR, r = -0.45); after 1 min of exercise for: cardiac index (CI, r = 0.49), mPAP (r = -0.57), RAP (r = -0.60), PWP (r = -0.45), and TPR (r = -0.67) and PVR (r = -0.38); at peak exercise for: tidal volume (r = 0.63), CI (r = 0.63), RAP (r = -0.43), TPR (r = -0.65) and PVR (r = -0.43). A significant linear correlation with peak oxygen consumption was found, for the increment between rest and 1 min of exercise, for RAP (r = -0.58) and CI (r = 0.42) and, for the increments between rest and peak exercise, for tidal volume (r = 0.79) and CI (r = 0.61) and, for the ratio between the increment between rest and 1 min of exercise/increment between rest and peak exercise, for mPAP (r = -0.42), RAP (r = 0.51) and CI (r = -0.54). The same ratio of increment of mPAP (r = 0.39) and CI (r = 0.36) correlated with that of tidal volume. This study provides evidence of a strong correlation between the respiratory function and pulmonary vascular pressure changes during

  18. Reproducibility of fractional ventilation derived by Fourier decomposition after adjusting for tidal volume with and without an MRI compatible spirometer. (United States)

    Voskrebenzev, Andreas; Gutberlet, Marcel; Becker, Lena; Wacker, Frank; Vogel-Claussen, Jens


    To reduce the influence of tidal volume on fractional ventilation (FV) derived by Fourier decomposition (FD). Twelve volunteers were examined on a 1.5 Tesla scanner. Spoiled gradient echo imaging of coronal and sagittal slices of the lung were performed. The tidal volume variations between different acquisitions were studied by reproducibility and repeatability measurements. To adjust the FV derived by FD for tidal volume differences between the measurements, during all acquisitions, the lung volume changes were measured by a spirometer and used to calculate a global FV parameter. As an alternative, using the FD data, the lung area changes were calculated and used for the adjustment. Reproducibility analysis of unadjusted coronal FV showed a determination coefficient of R2 = 71% and an intraclass correlation coefficient of ICC = 93%. Differences in the measurements could be ascribed to different tidal volumes. Area adjusted values exhibited an increased R2 of 84% and a higher ICC of 97%. For the coronal middle slice/sagittal slices in free breathing, the inter-volunteer coefficient of variation was reduced from 0.23/0.28 (unadjusted) to 0.16/0.20 (spirometer) or 0.12/0.13 (area). The calculation of lung area changes is sufficient to increase the reproducibility of FV in a volunteer cohort avoiding the need for an MRI compatible spirometer. Magn Reson Med 76:1542-1550, 2016. © 2015 International Society for Magnetic Resonance in Medicine. © 2015 International Society for Magnetic Resonance in Medicine.

  19. Evaluation the effect of breathing filters on end-tidal carbon dioxide during inferior abdominal surgery in infants and changes of tidal volume and respiratory rate needs for preventing of increasing end-tidal carbon dioxide

    Directory of Open Access Journals (Sweden)

    Parvin Sajedi


    Full Text Available Background: The aim of this study was to prevent of increasing end-tidal carbon dioxide (ETCO2with changing of vital capacity and respiratory rate when using of birthing filter in infants. Materials and Methods: In a randomized clinical trial study, ninety-four infant' patients were studied in three groups. Basic values, such as peak inspiratory pressure, tidal volume, minute ventilation, respiratory rate, and partial pressure of ET CO2 (PETCO2 level had been evaluated after intubation, 10 min after intubation and 10 min after filter insertion. In the first group, patients only observed for changing in ETCO2level. In the second and the third groups, respiratory rates and tidal volume had been increased retrospectively, until that ETCO2 ≤35 mmHg was received. We used ANOVA, Chi-square, and descriptive tests for data analysis. P< 0.05 was considered statistically significant. Results: Tidal volume 10 min after filter insertion was statistically higher in Group 3 (145.0 ± 26.3 ml versus 129.3 ± 38.9 ml in Group 1 and 118.7 ± 20.8 ml in Group 2 (P = 0.02. Furthermore, respiratory rate at this time was statistically higher in Group 2 (25.82 ± 0.43 versus Groups 1 and 3 (21.05 ± 0.20 ml and 21.02 ± 0.60 ml, respectively (P = 0.001. Minute volume and PETCO2level were statistically significant between Group 1 and the other two groups after filter insertion (P = 0.01 and P = 0.00,1 respectively. Conclusion: With changing the vital capacity and respiratory rate we can control PETCO2level ≤35 mmHg during using of birthing filters in infants. We recommend this instrument during anesthesia of infants.

  20. Association Between Use of Lung-Protective Ventilation With Lower Tidal Volumes and Clinical Outcomes Among Patients Without Acute Respiratory Distress Syndrome A Meta-analysis

    NARCIS (Netherlands)

    Serpa Neto, Ary; Cardoso, Sérgio Oliveira; Manetta, José Antônio; Pereira, Victor Galvão Moura; Espósito, Daniel Crepaldi; Pasqualucci, Manoela de Oliveira Prado; Damasceno, Maria Cecília Toledo; Schultz, Marcus J.


    Context Lung-protective mechanical ventilation with the use of lower tidal volumes has been found to improve outcomes of patients with acute respiratory distress syndrome (ARDS). It has been suggested that use of lower tidal volumes also benefits patients who do not have ARDS. Objective To determine

  1. Variability of Tidal Volume in Patient-Triggered Mechanical Ventilation in ARDS. (United States)

    Perinel-Ragey, Sophie; Baboi, Loredana; Guérin, Claude


    Limiting tidal volume (VT) in patients with ARDS may not be achieved once patient-triggered breaths occur. Furthermore, ICU ventilators offer numerous patient-triggered modes that work differently across brands. We systematically investigated, using a bench model, the effect of patient-triggered modes on the size and variability of VT at different breathing frequencies (f), patient effort, and ARDS severity. We used a V500 Infinity ICU ventilator connected to an ASL 5000 lung model whose compliance was mimicking mild, moderate, and severe ARDS. Thirteen patient-triggered modes were tested, falling into 3 categories, namely volume control ventilation with mandatory minute ventilation; pressure control ventilation, including airway pressure release ventilation (APRV); and pressure support ventilation. Two levels of f and effort were tested for each ARDS severity in each mode. Median (first-third quartiles) VT was compared across modes using non-parametric tests. The probability of VT > 6 mL/kg ideal body weight was assessed by binomial regression and expressed as the odds ratio (OR) with 95% CI. VT variability was measured from the coefficient of variation. VT distribution over all f, effort, and ARDS categories significantly differed across modes (P 6 mL/kg was significantly increased with spontaneous breaths patient-triggered by pressure support (OR 19.36, 95% CI 12.37-30.65) and significantly reduced in APRV (OR 0.44, 95% CI 0.26-0.72) and pressure support with guaranteed volume mode. The risk increased with increasing effort and decreasing f. Coefficient of variation of VT was greater for low f and volume control-mandatory minute ventilation and pressure control modes. APRV had the greatest within-mode variability. Risk of VT > 6 mL/kg was significantly reduced in APRV and pressure support with guaranteed volume mode. APRV had the highest variability. Pressure support with guaranteed volume could be tested in patients with ARDS. Copyright © 2017 by Daedalus

  2. Standardizing Predicted Body Weight Equations for Mechanical Ventilation Tidal Volume Settings. (United States)

    Linares-Perdomo, Olinto; East, Thomas D; Brower, Roy; Morris, Alan H


    Recent recommendations for lung protective mechanical ventilation include a tidal volume target of 6 mL/kg predicted body weight (PBW). Different PBW equations might introduce important differences in tidal volumes delivered to research subjects and patients. PBW equations use height, age, and sex as input variables. We compared National Institutes of Health (NIH) ARDS Network (ARDSNet), actuarial table (ACTUARIAL), and Stewart (STEWART) PBW equations used in clinical trials, across physiologic ranges for age and height. We used three-dimensional and two-dimensional surface analysis to compare these PBW equations. We then used age and height from actual clinical trial subjects to quantify PBW equation differences. Significant potential differences existed between these PBW predictions. The ACTUARIAL and ARDSNet surfaces for women were the only surfaces that intersected and produced both positive and negative differences. Mathematical differences between PBW equations at limits of height and age exceeded 30% in women and 24% in men for ACTUARIAL vs ARDSNet and about 25% for women and 15% for men for STEWART vs ARDSNet. The largest mathematical differences were present in older, shorter subjects, especially women. Actual differences for clinical trial subjects were as high as 15% for men and 24% for women. Significant differences between PBW equations for both men and women could be important sources of interstudy variation. Studies should adopt a standard PBW equation. We recommend using the NIH National Heart, Lung, and Blood Institute ARDS Network PBW equation because it is associated with the clinical trial that identified 6 mL/kg PBW as an appropriate target.

  3. Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents alveolar coagulation in patients without lung injury

    NARCIS (Netherlands)

    Choi, Goda; Wolthuis, Esther K.; Bresser, Paul; Levi, Marcel; van der Poll, Tom; Dzoljic, Misa; Vroom, Margreeth B.; Schultz, Marcus J.


    BACKGROUND: Alveolar fibrin deposition is a hallmark of acute lung injury, resulting from activation of coagulation and inhibition of fibrinolysis. Previous studies have shown that mechanical ventilation with high tidal volumes may aggravate lung injury in patients with sepsis and acute lung injury.

  4. Effect of a clinical decision support system on adherence to a lower tidal volume mechanical ventilation strategy

    NARCIS (Netherlands)

    Eslami, Saeid; de Keizer, Nicolette F.; Abu-Hanna, Ameen; de Jonge, Evert; Schultz, Marcus J.


    PURPOSE: The purpose of the study was to measure the effect of a computerized decision support system (CDSS) on adherence to tidal volume (V(T)) recommendations. MATERIALS AND METHODS: We performed a prospective before-after evaluation study on applied V(T) to examine the impact of a CDSS on

  5. One-Lung Ventilation with Additional Ipsilateral Ventilation of Low Tidal Volume and High Frequency in Lung Lobectomy. (United States)

    Feng, Yong; Wang, Jianyue; Zhang, Yang; Wang, Shiduan


    BACKGROUND To investigate the protective effects of additional ipsilateral ventilation of low tidal volume and high frequency on lung functions in the patients receiving lobectomy. MATERIAL AND METHODS Sixty patients receiving lung lobectomy were randomized into the conventional one-lung ventilation (CV) group (n=30) and the ipsilateral low tidal volume high frequency ventilation (LV) group (n=30). In the CV group, patients received only contralateral OLV. In the LV group, patients received contralateral ventilation and additional ipsilateral ventilation of low tidal volume of 1-2 ml/kg and high frequency of 40 times/min. Normal lung tissues were biopsied for the analysis of lung injury. Lung injury was scored by evaluating interstitial edema, alveolar edema, neutrophil infiltration, and alveolar congestion. RESULTS At 30 min and 60 min after the initiation of one-lung ventilation and after surgery, patients in the LV group showed significantly higher ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen than those in the CV group (PLung injury was significantly less severe (2.7±0.7) in the LV group than in the CV group (3.1±0.7) (P=0.006). CONCLUSIONS Additional ipsilateral ventilation of low tidal volume and high frequency can decrease the risk of hypoxemia and alleviate lung injury in patients receiving lobectomy.

  6. Low tidal volume protects pulmonary vasomotor function from “second-hit” injury in acute lung injury rats

    Directory of Open Access Journals (Sweden)

    Pan Chun


    Full Text Available Abstract Background Sepsis could induce indirect acute lung injury(ALI, and pulmonary vasomotor dysfunction. While low tidal volume is advocated for treatment of ALI patients. However, there is no evidence for low tidal volume that it could mitigate pulmonary vasomotor dysfunction in indirect ALI. Our study is to evaluate whether low tidal volume ventilation could protect the pulmonary vascular function in indirect lipopolysaccharide (LPS induced acute lung injury rats. Methods An indirect ALI rat model was induced by intravenous infusion of LPS. Thirty rats (n = 6 in each group were randomly divided into (1Control group; (2 ALI group; (3 LV group (tidal volume of 6mL/kg; (4 MV group (tidal volume of 12mL/kg; (5VLV group (tidal volume of 3mL/kg. Mean arterial pressure and blood gas analysis were monitored every 2 hours throughout the experiment. Lung tissues and pulmonary artery rings were immediately harvested after the rats were bled to be killed to detect the contents of endothelin-1 (ET-1, endothelial nitric oxide synthase (eNOS and TNF-α. Acetylcholine (Ache-induced endothelium-dependent and sodium nitroprusside (SNP-induced endothelium-independent relaxation of isolated pulmonary artery rings were measured by tensiometry. Results There was no difference within groups concerning blood pressure, PaCO2 and SNP-induced endothelium-independent relaxation of pulmonary artery rings. Compared with MV group, LV group significantly reduced LPS-induced expression of ET-1 level (113.79 ± 7.33pg/mL vs. 152.52 ± 12.75pg/mL, P P P -7mol/L-10-4mol/L-induced vasodilatation was ameliorated 30% more in LV group than in MV group. Conclusions Low tidal volume could protect the pulmonary vasodilative function during indirect ALI by decreasing vasoconstrictor factors, increasing expressions of vasodilator factors in pulmonary endothelial cells, and inhibiting inflammation injuries.

  7. Prolonged slow expiration technique in infants: effects on tidal volume, peak expiratory flow, and expiratory reserve volume. (United States)

    Lanza, Fernanda C; Wandalsen, Gustavo; Dela Bianca, Ana Caroline; Cruz, Carolina L; Postiaux, Guy; Solé, Dirceu


    Prolonged slow expiration (PSE) is a physiotherapy technique often applied in infants to reduce pulmonary obstruction and clear secretions, but there have been few studies of PSE's effects on the respiratory system. To describe PSE's effects on respiratory mechanics in infants. We conducted a cross-sectional study with 18 infants who had histories of recurrent wheezing. The infants were sedated for lung-function testing, which was followed by PSE. The PSE consisted of 3 sequences of prolonged manual thoraco-abdominal compressions during the expiratory phase. We measured peak expiratory flow (PEF), tidal volume (V(T)), and the frequency of sighs during and immediately after PSE. We described the exhaled volume during PSE as a fraction of expiratory reserve volume (%ERV). We quantified ERV with the raised-volume rapid-thoracic-compression technique. The cohort's mean age was 32.2 weeks, and they had an average of 4.8 previous wheezing episodes. During PSE there was significant V(T) reduction (80 ± 17 mL vs 49 ± 11 mL, P < .001), no significant change in PEF (149 ± 32 mL/s vs 150 ± 32 mL/s, P = .54), and more frequent sighs (40% vs 5%, P = .03), compared to immediately after PSE. The exhaled volume increased in each PSE sequence (32 ± 18% of ERV, 41 ± 24% of ERV, and 53 ± 20% of ERV, P = .03). It was possible to confirm and quantify that PSE deflates the lung to ERV. PSE caused no changes in PEF, induced sigh breaths, and decreased V(T), which is probably the main mechanical feature for mucus clearance.

  8. Very low tidal volume ventilation with associated hypercapnia--effects on lung injury in a model for acute respiratory distress syndrome.

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    Hans Fuchs

    Full Text Available BACKGROUND: Ventilation using low tidal volumes with permission of hypercapnia is recommended to protect the lung in acute respiratory distress syndrome. However, the most lung protective tidal volume in association with hypercapnia is unknown. The aim of this study was to assess the effects of different tidal volumes with associated hypercapnia on lung injury and gas exchange in a model for acute respiratory distress syndrome. METHODOLOGY/PRINCIPAL FINDINGS: In this randomized controlled experiment sixty-four surfactant-depleted rabbits were exposed to 6 hours of mechanical ventilation with the following targets: Group 1: tidal volume = 8-10 ml/kg/PaCO(2 = 40 mm Hg; Group 2: tidal volume = 4-5 ml/kg/PaCO(2 = 80 mm Hg; Group 3: tidal volume = 3-4 ml/kg/PaCO(2 = 120 mm Hg; Group 4: tidal volume = 2-3 ml/kg/PaCO(2 = 160 mm Hg. Decreased wet-dry weight ratios of the lungs, lower histological lung injury scores and higher PaO(2 were found in all low tidal volume/hypercapnia groups (group 2, 3, 4 as compared to the group with conventional tidal volume/normocapnia (group 1. The reduction of the tidal volume below 4-5 ml/kg did not enhance lung protection. However, oxygenation and lung protection were maintained at extremely low tidal volumes in association with very severe hypercapnia and no adverse hemodynamic effects were observed with this strategy. CONCLUSION: Ventilation with low tidal volumes and associated hypercapnia was lung protective. A tidal volume below 4-5 ml/kg/PaCO(2 80 mm Hg with concomitant more severe hypercapnic acidosis did not increase lung protection in this surfactant deficiency model. However, even at extremely low tidal volumes in association with severe hypercapnia lung protection and oxygenation were maintained.

  9. [Efficacy of preoxygenation using tidal volume breathing: a comparison of Mapleson A, Bain's and Circle system]. (United States)

    Arora, Suman; Gupta, Priyanka; Arya, Virender Kumar; Bhatia, Nidhi

    Efficacy of preoxygenation depends upon inspired oxygen concentration, its flow rate, breathing system configuration and patient characteristics. We hypothesized that in actual clinical scenario, where breathing circuit is not primed with 100% oxygen, patients may need more time to achieve EtO 2 ≥90%, and this duration may be different among various breathing systems. We thus studied the efficacy of preoxygenation using unprimed Mapleson A, Bain's and Circle system with tidal volume breathing at oxygen flow rates of 5L.min -1 and 10L.min -1 . Patients were randomly allocated into one of the six groups, wherein they were preoxygenated using either Mapleson A, Bain's or Circle system at O 2 flow rate of either 5L.min -1 or 10L.min -1 . The primary outcome measure of our study was the time taken to achieve EtO 2 ≥90% at 5 and 10L.min -1 flow rates. At oxygen flow rate of 5L.min -1 , time to reach EtO 2 ≥90% was significantly longer with Bain's system (3.7±0.67min) than Mapleson A and Circle system (2.9±0.6, 3.3±0.97min, respectively). However at oxygen flow rate of 10L.min -1 this time was significantly shorter and comparable among all the three breathing systems (2.33±0.38min with Mapleson, 2.59±0.50min with Bain's and 2.60±0.47min with Circle system). With spontaneous normal tidal volume breathing at oxygen flow rate of 5L.min -1 , Mapleson A can optimally preoxygenate patients within 3min while Bain's and Circle system require more time. However at O 2 flow rate of 10L.min -1 all the three breathing systems are capable of optimally preoxygenating the patients in less than 3min. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  10. Optimal Respiratory Rate for Low-Tidal Volume and Two-Lung Ventilation in Thoracoscopic Bleb Resection. (United States)

    Lee, Dong Kyu; Kim, Hyun Koo; Lee, Kanghoon; Choi, Young Ho; Lim, Sang Ho; Kim, Heezoo


    One-lung ventilation is considered to be mandatory in video-assisted thoracoscopic surgery. However, the authors showed in a previous report that two-lung ventilation with low tidal volume is feasible in thoracoscopic bleb resection (TBR). In this study, they evaluated optimal respiratory rate during TBR under two-lung ventilation with low-tidal volume anesthesia. A prospective, randomized, single-blinded intervention study. An operating room in a teaching hospital. Forty-eight patients who underwent scheduled TBR under general anesthesia. TBR was performed under low-tidal-volume (5 mL/kg), two-lung ventilation. Respiratory rate (RR) varied according to the protocol: 15 (group I), 18 (group II), and 22 cycles/min (group III). Using block randomization method, 16 patients were assigned to each of 3 groups. Minute ventilation of group I was lowered significantly compared with the other groups (plung ventilation did not produce abnormal physiologic changes including arterial pH, partial arterial oxygen pressure, and partial pressure of carbon dioxide and guaranteed an optimal surgical field. Therefore, these setting are considered acceptable for two-lung ventilation during TBR. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Low tidal volume ventilation use remains low in patients with acute respiratory distress syndrome at a single center. (United States)

    Spece, Laura J; Mitchell, Kristina H; Caldwell, Ellen S; Gundel, Stephanie J; Jolley, Sarah E; Hough, Catherine L


    Low tidal volume ventilation (LTVV) reduces mortality in acute respiratory distress syndrome (ARDS) patients. Understanding local barriers to LTVV use at a former ARDS Network hospital may provide new insight to improve LTVV implementation. A cohort of 214 randomly selected adults met the Berlin definition of ARDS at Harborview Medical Center between 2008 and 2012. The primary outcome was the receipt of LTVV (tidal volume of ≤6.5mL/kg predicted body weight) within 48h of ARDS onset. We constructed a multivariable logistic regression model to identify factors associated with the outcome. Only 27% of patients received tidal volumes of ≤6.5mL/kg PBW within 48h of ARDS onset. Increasing plateau pressure (OR 1.11; 95% CI 1.03 to 1.19; p-value<0.01) was positively associated with LTVV use while increasing PaO 2 :F I O 2 ratio was negatively associated (OR 0.75; 95% CI 0.57 to 0.98; p-value 0.03). Physicians documented an ARDS diagnosis in only 21% of the cohort. Neither patient height nor gender was associated with LTVV use. Most ARDS patients did not receive LTVV despite implementation of a protocol. ARDS was also recognized in a minority of patients, suggesting an opportunity for improvement of care. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Reduced anterior cingulate gray matter volume in treatment-naïve clinically depressed adolescents

    Directory of Open Access Journals (Sweden)

    Justine Nienke Pannekoek


    Full Text Available Adolescent depression is associated with increased risk for suicidality, social and educational impairment, smoking, substance use, obesity, and depression in adulthood. It is of relevance to further our insight in the neurobiological mechanisms underlying this disorder in the developing brain, as this may be essential to optimize treatment and prevention of adolescent depression and its negative clinical trajectories. The equivocal findings of the limited number of studies on neural abnormalities in depressed youth stress the need for further neurobiological investigation of adolescent depression. We therefore performed a voxel-based morphometry study of the hippocampus, amygdala, superior temporal gyrus, and anterior cingulate cortex (ACC in 26 treatment-naïve, clinically depressed adolescents and 26 pair-wise matched healthy controls. Additionally, an exploratory whole-brain analysis was performed. Clinically depressed adolescents showed a volume reduction of the bilateral dorsal ACC compared to healthy controls. However, no association was found between gray matter volume of the ACC and clinical severity scores for depression or anxiety. Our finding of a smaller ACC in clinically depressed adolescents is consistent with literature on depressed adults. Future research is needed to investigate if gray matter abnormalities precede or follow clinical depression in adolescents.

  13. Reduced anterior cingulate gray matter volume in treatment-naïve clinically depressed adolescents☆ (United States)

    Pannekoek, Justine Nienke; van der Werff, Steven J.A.; van den Bulk, Bianca G.; van Lang, Natasja D.J.; Rombouts, Serge A.R.B.; van Buchem, Mark A.; Vermeiren, Robert R.J.M.; van der Wee, Nic J.A.


    Adolescent depression is associated with increased risk for suicidality, social and educational impairment, smoking, substance use, obesity, and depression in adulthood. It is of relevance to further our insight in the neurobiological mechanisms underlying this disorder in the developing brain, as this may be essential to optimize treatment and prevention of adolescent depression and its negative clinical trajectories. The equivocal findings of the limited number of studies on neural abnormalities in depressed youth stress the need for further neurobiological investigation of adolescent depression. We therefore performed a voxel-based morphometry study of the hippocampus, amygdala, superior temporal gyrus, and anterior cingulate cortex (ACC) in 26 treatment-naïve, clinically depressed adolescents and 26 pair-wise matched healthy controls. Additionally, an exploratory whole-brain analysis was performed. Clinically depressed adolescents showed a volume reduction of the bilateral dorsal ACC compared to healthy controls. However, no association was found between gray matter volume of the ACC and clinical severity scores for depression or anxiety. Our finding of a smaller ACC in clinically depressed adolescents is consistent with literature on depressed adults. Future research is needed to investigate if gray matter abnormalities precede or follow clinical depression in adolescents. PMID:24501702

  14. Accuracy of height estimation and tidal volume setting using anthropometric formulas in an ICU Caucasian population. (United States)

    L'her, Erwan; Martin-Babau, Jérôme; Lellouche, François


    Knowledge of patients' height is essential for daily practice in the intensive care unit. However, actual height measurements are unavailable on a daily routine in the ICU and measured height in the supine position and/or visual estimates may lack consistency. Clinicians do need simple and rapid methods to estimate the patients' height, especially in short height and/or obese patients. The objectives of the study were to evaluate several anthropometric formulas for height estimation on healthy volunteers and to test whether several of these estimates will help tidal volume setting in ICU patients. This was a prospective, observational study in a medical intensive care unit of a university hospital. During the first phase of the study, eight limb measurements were performed on 60 healthy volunteers and 18 height estimation formulas were tested. During the second phase, four height estimates were performed on 60 consecutive ICU patients under mechanical ventilation. In the 60 healthy volunteers, actual height was well correlated with the gold standard, measured height in the erect position. Correlation was low between actual and calculated height, using the hand's length and width, the index, or the foot equations. The Chumlea method and its simplified version, performed in the supine position, provided adequate estimates. In the 60 ICU patients, calculated height using the simplified Chumlea method was well correlated with measured height (r = 0.78; ∂ set according to these estimates was lower than what would have been set using the actual weight. When actual height is unavailable in ICU patients undergoing mechanical ventilation, alternative anthropometric methods to obtain patient's height based on lower leg and on forearm measurements could be useful to facilitate the application of protective mechanical ventilation in a Caucasian ICU population. The simplified Chumlea method is easy to achieve in a bed-ridden patient and provides accurate height estimates

  15. Tidal Volume Delivery during the Anesthetic Management of Neonates Is Variable. (United States)

    Abouzeid, Thanaa; Perkins, Elizabeth J; Pereira-Fantini, Prue M; Rajapaksa, Anushi; Suka, Asha; Tingay, David G


    To describe expiratory tidal volume (VT) during routine anesthetic management of neonates at a single tertiary neonatal surgical center, as well as the proportion of VT values within the range of 4.0-8.0 mL/kg. A total of 26 neonates needing surgery under general anesthesia were studied, of whom 18 were intubated postoperatively. VT was measured continuously during normal clinical care using a dedicated neonatal respiratory function monitor (RFM), with clinicians blinded to values. VT, pressure, and cardiorespiratory variables were recorded regularly while intubated intraoperatively, during postoperative transport, and for 15 minutes after returning to the neonatal intensive care unit (NICU). In addition, paired VT values from the anesthetic machine were documented intraoperatively. A total of 2597 VT measures were recorded from 26 neonates. Intraoperative and postoperative transport expiratory VT values were highly variable compared with the NICU VT (P inflations outside the 4.0-8.0 mL/kg range (35% and 38% of VT >8.0 mL/kg, respectively), compared with 29% in the NICU (P inflating bag resulted in a median (range) VT of 8.5 mL/kg (range, 5.3-11.4 mL/kg) vs 5.6 ml/kg (range, 4.3-7.9 mL/kg) using a Neopuff T-piece system (P < .0001, Mann-Whitney U test). The mean anesthetic machine expiratory VT was 3.2 mL/kg (95% CI, -4.5 to 10.8 mL/kg) above RFM. VT is highly variable during the anesthetic care of neonates, and potentially injurious VT is frequently delivered; thus, we suggest close VT monitoring using a dedicated neonatal RFM. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Employing an Incentive Spirometer to Calibrate Tidal Volumes Estimated from a Smartphone Camera

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    Bersain A. Reyes


    Full Text Available A smartphone-based tidal volume (VT estimator was recently introduced by our research group, where an Android application provides a chest movement signal whose peak-to-peak amplitude is highly correlated with reference VT measured by a spirometer. We found a Normalized Root Mean Squared Error (NRMSE of 14.998% ± 5.171% (mean ± SD when the smartphone measures were calibrated using spirometer data. However, the availability of a spirometer device for calibration is not realistic outside clinical or research environments. In order to be used by the general population on a daily basis, a simple calibration procedure not relying on specialized devices is required. In this study, we propose taking advantage of the linear correlation between smartphone measurements and VT to obtain a calibration model using information computed while the subject breathes through a commercially-available incentive spirometer (IS. Experiments were performed on twelve (N = 12 healthy subjects. In addition to corroborating findings from our previous study using a spirometer for calibration, we found that the calibration procedure using an IS resulted in a fixed bias of −0.051 L and a RMSE of 0.189 ± 0.074 L corresponding to 18.559% ± 6.579% when normalized. Although it has a small underestimation and slightly increased error, the proposed calibration procedure using an IS has the advantages of being simple, fast, and affordable. This study supports the feasibility of developing a portable smartphone-based breathing status monitor that provides information about breathing depth, in addition to the more commonly estimated respiratory rate, on a daily basis.

  17. Large-scale tidal effect on redshift-space power spectrum in a finite-volume survey (United States)

    Akitsu, Kazuyuki; Takada, Masahiro; Li, Yin


    Long-wavelength matter inhomogeneities contain cleaner information on the nature of primordial perturbations as well as the physics of the early Universe. The large-scale coherent overdensity and tidal force, not directly observable for a finite-volume galaxy survey, are both related to the Hessian of large-scale gravitational potential and therefore are of equal importance. We show that the coherent tidal force causes a homogeneous anisotropic distortion of the observed distribution of galaxies in all three directions, perpendicular and parallel to the line-of-sight direction. This effect mimics the redshift-space distortion signal of galaxy peculiar velocities, as well as a distortion by the Alcock-Paczynski effect. We quantify its impact on the redshift-space power spectrum to the leading order, and discuss its importance for ongoing and upcoming galaxy surveys.

  18. Non-invasive measurement of the mean alveolar O(2) tension from the oxygen uptake versus tidal volume curve. (United States)

    Jordanoglou, J; Latsi, P; Chroneou, A; Koulouris, N G


    The classical equations for measuring the mean and the ideal alveolar O(2) tension are based on assumptions, which are shown to be invalid. So we thought to develop a new, non-invasive method for measuring the mean alveolar P,O(2) within the volume domain (PA,O(2(Bohr))). This method is based on the oxygen uptake vs. tidal volume curve (VO(2) vs. VT) obtained during tidal breathing of room air and/or air enriched with oxygen. PA,O(2(Bohr)) and the ideal alveolar PO(2) (PA,O(2(ideal))) were simultaneously measured in 10 healthy subjects and 34 patients suffering from chronic obstructive pulmonary disease (COPD) breathing tidally room air at rest. Additionally, 10 subjects (three healthy subjects and seven COPD patients) were studied while breathing initially room air and subsequently air enriched with oxygen. According to the results, PA,O(2(Bohr)) considerably differed from PA,O(2(ideal)) (P = 0.004). The cause of the difference, at the individual's R, is: (1) the difference between the arterial and Bohr's alveolar CO(2) tension, mainly in COPD patients, and (2) the inequality between Bohr's alveolar part of the tidal volume for CO(2) and O(2). Furthermore, end-tidal gas tension (PET,CO(2) and PET,O(2)) differed from Pa,CO(2) and PA,O(2(Bohr)) respectively. The deviation of PA,O(2(Bohr)) from PA,O(2(ideal)) has a definite impact on Bohr's dead space ratio for O(2) and CO(2), and on the alveolar-arterial O(2) difference. The difference (PA,O(2(Bohr)) - PA,O(2(ideal))) is not related to the pathology of the disease. So, gas exchange within the lungs should be assessed at the subject's R from PA,O(2(Bohr)) and PA,CO(2(Bohr)) but not from PA,O(2(ideal)) nor Pa,CO(2).

  19. Expression of aquaporins 1 and 5 in a model of ventilator-induced lung injury and its relation to tidal volume. (United States)

    Fabregat, Gustavo; García-de-la-Asunción, José; Sarriá, Benjamín; Mata, Manuel; Cortijo, Julio; de Andrés, José; Gallego, Lucía; Belda, Francisco Javier


    What is the central question of this study? Although different studies have attempted to find factors that influence the expression of aquaporins (AQPs) in the lung in different situations, to date no research group has explored the expression of AQP1 and AQP5 jointly in rats mechanically ventilated with different tidal volumes in a model of ventilator-induced lung injury. What is the main finding? Mechanical ventilation with a high tidal volume causes lung injury and oedema, increasing lung permeability. In rats ventilated with a high tidal volume, the pulmonary expression of AQP1 decreases. We analysed the expression of aquaporins 1 and 5 and its relation with tidal volume in a model of ventilator-induced lung injury. Forty-two rats were used. Six non-ventilated animals were killed (control group). The remaining rats were ventilated for 2 h with different tidal volumes (group 7ML with 7 ml kg-1 and group 20ML with 20 ml kg-1 ) and a respiratory rate of 90 breaths min-1 . Lung oedema was measured, and the expression of AQP1 and AQP5 was determined by Western immunoblotting and measurement of mRNA. Lung oedema and alveolar-capillary membrane permeability were significantly increased in the animals of group 20ML compared with the control group. Expression of AQP1 was decreased in groups 7ML and 20ML compared with the control group. In conclusion, mechanical ventilation with a high tidal volume causes lung injury and oedema, increasing lung permeability. In rats ventilated with a high tidal volume, the pulmonary expression of AQP1 decreases. © 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.

  20. Determination of regional lung air volume distribution at mid-tidal breathing from computed tomography: a retrospective study of normal variability and reproducibility. (United States)

    Fleming, John; Conway, Joy; Majoral, Caroline; Bennett, Michael; Caillibotte, Georges; Montesantos, Spyridon; Katz, Ira


    Determination of regional lung air volume has several clinical applications. This study investigates the use of mid-tidal breathing CT scans to provide regional lung volume data. Low resolution CT scans of the thorax were obtained during tidal breathing in 11 healthy control male subjects, each on two separate occasions. A 3D map of air volume was derived, and total lung volume calculated. The regional distribution of air volume from centre to periphery of the lung was analysed using a radial transform and also using one dimensional profiles in three orthogonal directions. The total air volumes for the right and left lungs were 1035 +/- 280 ml and 864 +/- 315 ml, respectively (mean and SD). The corresponding fractional air volume concentrations (FAVC) were 0.680 +/- 0.044 and 0.658 +/- 0.062. All differences between the right and left lung were highly significant (p lung air volumes and FAVC were 6.5% and 6.9% and 2.5% and 3.6%, respectively. FAVC correlated significantly with lung space volume (r = 0.78) (p lung. Central to peripheral ratios were significantly higher for the right (0.100 +/- 0.007 SD) than the left (0.089 +/- 0.013 SD) (p volume in the lung at mid-tidal breathing is described. Mean values and reproducibility are described for healthy male control subjects. Fractional air volume concentration is shown to increase with lung size.

  1. Higher Fresh Gas Flow Rates Decrease Tidal Volume During Pressure Control Ventilation. (United States)

    Mohammad, Shazia; Gravenstein, Nikolaus; Gonsalves, Drew; Vasilopoulos, Terrie; Lampotang, Samsun


    We observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV. To model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare). For the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva. FGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow

  2. Novel approach to the exploitation of the tidal energy. Volume 1: Summary and discussion (United States)

    Gorlov, A. M.


    The hydropneumatic concept in the approach to harnessing low tidal hydropower is discussed. The energy of water flow is converted into the energy of an air jet by a specialized air chamber which is placed on the ocean floor across a flowing watercourse. Water passes through the chamber where it works as a natural piston compressing air in the upper part of the closure. Compressed air is used as a new working plenum to drive air turbines. The kinetic energy of an air jet provided by the air chamber is sufficient for stable operation of industrial air turbines. It is possible to use light plastic barriers instead of conventional rigid dams (the water sail concept). It is confirmed that the concept can result in a less expensive and more effective tidal power plant project than the conventional hydroturbine approach.

  3. Tidal Volume Delivery and Endotracheal Tube Leak during Cardiopulmonary Resuscitation in Intubated Newborn Piglets with Hypoxic Cardiac Arrest Exposed to Different Modes of Ventilatory Support. (United States)

    Mendler, Marc R; Weber, Claudia; Hassan, Mohammad A; Huang, Li; Mayer, Benjamin; Hummler, Helmut D


    There are few data available on the interaction of inflations, chest compressions (CC), and delivery of tidal volumes in newborn infants undergoing resuscitation in the presence of endotracheal tube (ET) leaks. To determine the effects of different respiratory support strategies along with CC on changes in tidal volume and ET leaks in hypoxic newborn piglets with cardiac arrest. Asphyxiated newborn piglets, intubated with weight-adapted uncuffed ET, were randomized into three groups and resuscitated according to ILCOR 2010 guidelines: (1) T-piece resuscitator (TPR) group = peak inspiratory pressure (PIP)/positive end-expiratory pressure (PEEP) 25/5 cm H2O, rate 30/min, inflations interposed between CC (3:1 ratio); (2) self- inflating bag (SIB) group = PIP 25 cm H2O without PEEP, rate 30/min, inflations interposed between CC (3:1 ratio), and (3) ventilator group = PIP/PEEP of 25/5 cm H2O, rate 30/min. CC were applied with a rate of 120/min without synchrony to inflations. We observed a significant increase of leak (average increase 11.4%) when CC was added to respiratory support (p = 0.0001). Expired tidal volume was larger in the SIB group than in the two other modes which both applied PEEP. However, tidal volumes caused by CC only were larger in the two groups with PEEP than in the SIB group (without PEEP). There is interaction between lung inflations and CC affecting leak and delivery of tidal volume, which may be influenced by the mode/device used for respiratory support. Leak is larger in the presence of PEEP. However, CC cause additional tidal volume which is larger in the presence of PEEP. © 2016 S. Karger AG, Basel.

  4. Tidal volume single breath washout of two tracer gases--a practical and promising lung function test.

    Directory of Open Access Journals (Sweden)

    Florian Singer

    Full Text Available BACKGROUND: Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI, which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW of sulfur hexafluoride (SF(6 and helium (He using an ultrasonic flowmeter (USFM. METHODS: The tracer gas mixture contained 5% SF(6 and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC, were determined in seven subjects performing three SBW 24 hours apart. RESULTS: USFM reliably measured MM during all SBW tests (n = 60. MM from USFM reflected SF(6 and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%. CONCLUSION: The USFM accurately measured relative changes in SF(6 and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF(6 and He washout patterns during tidal breathing.

  5. Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution. (United States)

    Kozian, Alf; Schilling, Thomas; Schütze, Hartmut; Senturk, Mert; Hachenberg, Thomas; Hedenstierna, Göran


    The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

  6. Relationship between Interleukin-6 gene polymorphism and hippocampal volume in antipsychotic-naïve schizophrenia: evidence for differential susceptibility?

    Directory of Open Access Journals (Sweden)

    Sunil Vasu Kalmady

    Full Text Available Various lines of evidence including epidemiological, genetic and foetal pathogenetic models suggest a compelling role for Interleukin-6 (IL-6 in the pathogenesis of schizophrenia. IL-6 mediated inflammatory response triggered by maternal infection or stress induces disruption of prenatal hippocampal development which might contribute towards psychopathology during adulthood. There is a substantial lack of knowledge on how genetic predisposition to elevated IL-6 expression effects hippocampal structure in schizophrenia patients. In this first-time study, we evaluated the relationship between functional polymorphism rs1800795 of IL-6 and hippocampal gray matter volume in antipsychotic-naïve schizophrenia patients in comparison with healthy controls.We examined antipsychotic-naïve schizophrenia patients [N = 28] in comparison with healthy controls [N = 37] group matched on age, sex and handedness. Using 3 Tesla - MRI, bilateral hippocampi were manually segmented by blinded raters with good inter-rater reliability using a valid method. Additionally, Voxel-based Morphometry (VBM analysis was performed using hippocampal mask. The IL-6 level was measured in blood plasma using ELISA technique. SNP rs1800795 was genotyped using PCR and DNA sequencing. Psychotic symptoms were assessed using Scale for Assessment of Positive Symptoms and Scale for Assessment of Negative Symptoms.Schizophrenia patients had significantly deficient left and right hippocampal volumes after controlling for the potential confounding effects of age, sex and total brain volume. Plasma IL-6 levels were significantly higher in patients than controls. There was a significant diagnosis by rs1800795 genotype interaction involving both right and left hippocampal volumes. Interestingly, this effect was significant only in men but not in women.Our first time observations suggest a significant relationship between IL-6 rs1800795 and reduced hippocampal volume in antipsychotic-naïve

  7. Factors of tidal volume variation during augmented spontaneous ventilation in patients on extracorporeal carbon dioxide removal. A multivariate analysis. (United States)

    Bein, T; Müller, T; Graf, B M; Philipp, A; Zeman, F; Schultz, M J; Slutsky, A S; Weber-Carstens, S


    Extracorporeal carbon dioxide removal (ECCO2-R) allows lung protective ventilation using lower tidal volumes (VT) in patients with acute respiratory failure. The dynamics of spontaneous ventilation under ECCO2-R has not been described previously. This retrospective multivariable analysis examines VT patterns and investigates the factors that influence VT, in particular sweep gas flow and blood flow through the artificial membrane. We assessed VT, respiratory rate (RR), minute ventilation (MV), and levels of pressure support (0-24 cm H2O), sweep gas flow (0-14 L/min) and blood flow through the membrane (0.8-1.8 L/min) in 40 patients from the moment they were allowed to breathe spontaneously. Modest hypercapnia was accepted. Patients tolerated moderate hypercapnia well. In a generalized linear model the increase in sweep gas flow (Pventilation. Such a technique can be used for prolonged lung protective ventilation even in the patient's recovery period.

  8. Effect of inspiratory flow rate on the efficiency of carbon dioxide removal at tidal volumes below instrumental dead space. (United States)

    Hurley, Edward H; Keszler, Martin


    The ability to ventilate babies with tidal volumes (VTs) below dead space has been demonstrated both in vivo and in vitro, though it appears to violate classical respiratory physiology. We hypothesised that this phenomenon is made possible by rapid flow of gas that penetrates the dead space allowing fresh gas to reach the lungs and that the magnitude of this phenomenon is affected by flow rate or how rapidly air flows through the endotracheal tube. We conducted two bench experiments. First, we measured the time needed for complete CO2 washout from a test lung to assess how fixed VT but different inflation flow rates affect ventilation. For the second experiment, we infused carbon dioxide at a low rate into the test lung, varied the inflation flow rate and adjusted the VT to maintain stable end tidal carbon dioxide (ETCO2). At all tested VTs, lower flow rate increased the time it took for CO2 to washout from the test lung. The effect was most pronounced for VTs below dead space. The CO2 steady-state experiment showed that ETCO2 increased when the flow rate decreased. Ventilating with a slower flow rate required a nearly 20% increase in VT for the same effective alveolar ventilation. Inflation flow rate affects the efficiency of CO2 removal with low VT. Our results are relevant for providers using volume-controlled ventilation or other modes that use low inflation flow rates because the VT required for normocapnia will be higher than published values that were generated using pressure-limited ventilation modes with high inflation flows. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to

  9. Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents pulmonary inflammation in patients without preexisting lung injury

    NARCIS (Netherlands)

    Wolthuis, Esther K.; Choi, Goda; Dessing, Mark C.; Bresser, Paul; Lutter, Rene; Dzoljic, Misa; van der Poll, Tom; Vroom, Margreeth B.; Hollmann, Markus; Schultz, Marcus J.


    Background: Mechanical ventilation with high tidal volumes aggravates lung injury in patients with acute lung injury or acute respiratory distress syndrome. The authors sought to determine the effects of short-term mechanical ventilation on local inflammatory responses in patients without

  10. Lung-protective ventilation in intensive care unit and operation room : Tidal volume size, level of positive end-expiratory pressure and driving pressure

    NARCIS (Netherlands)

    Serpa Neto, A.


    Several investigations have shown independent associations between three ventilator settings – tidal volume size, positive end–expiratory pressure (PEEP) and driving pressure – and outcomes in patients with the acute respiratory distress syndrome (ARDS). There is an increasing notion that similar

  11. Increased tidal volume variability in children is a better marker of opioid-induced respiratory depression than decreased respiratory rate. (United States)

    Barbour, Sean J; Vandebeek, Christine A; Ansermino, J Mark


    During opioid administration, decreasing respiratory rate is typically used as a predictor of respiratory depression. Prior to opioid-induced apnea, progressively irregular breathing patterns have been noticed. We hypothesize that opioid administration to children will increase tidal volume variability (TV(var)) and that this will be a better predictor of respiratory depression than a decrease in respiratory rate. We recruited 32 children aged 2-8 years scheduled to undergo surgery. During spontaneous ventilation, flow rates and respiratory rates were continuously recorded, while remifentanil was infused at stepwise increasing doses each lasting 10 min. The infusion was continued until the patient showed signs of respiratory depression. Flow data from each dose was used to calculate tidal volumes, from which TV(var) was calculated. The respiratory rate and TV(var) during the last (D(last)), second to last (D-2), and third to last (D-3), administered doses were compared to those during baseline (fourth to last dose). We chose a threshold of TV(var) increase and compared it to a decrease in respiratory rate below 10 breaths per min as predictors of respiratory depression. Compared to baseline, the TV(var) increased by 336% and 668% during D(-2) and D(last), respectively, whereas respiratory rate decreased by 14.3%, 31.7%, and 55.5% during D(-3), D(-2), and D(last), respectively. A threshold increase in TV(var) of 150% over baseline correctly predicted respiratory depression in 41% of patients, compared to a drop in respiratory rate correctly predicting 22% of patients. TV(var) increases as children approach opioid-induced respiratory depression. This is a more useful predictor of respiratory depression than a fall in respiratory rate because the TV(var) increase is 10 times the drop in respiratory rate. A TV(var) increase also correctly predicts respiratory depression twice as often as decreased respiratory rate and is independent of age-related alterations in

  12. Efficacy of a Low-Tidal Volume Ventilation Strategy to Prevent Reperfusion Lung Injury after Pulmonary Thromboendarterectomy. (United States)

    Bates, Dina M; Fernandes, Timothy M; Duwe, Beau V; King, Bryan O; Banks, Dalia A; Test, Victor J; Fedullo, Peter F; Kim, Nick H; Madani, Michael M; Jamieson, Stuart W; Auger, William R; Kerr, Kim M


    Reperfusion lung injury is a postoperative complication of pulmonary thromboendarterectomy that can significantly affect morbidity and mortality. Studies in other postoperative patient populations have demonstrated a reduction in acute lung injury with the use of a low-tidal volume (Vt) ventilation strategy. Whether this approach benefits patients undergoing thromboendarterectomy is unknown. We sought to determine if low-Vt ventilation reduces reperfusion lung injury in patients with chronic thromboembolic pulmonary hypertension undergoing thromboendarterectomy. Patients undergoing thromboendarterectomy at one center were randomized to receive either low (6 ml/kg predicted body weight) or usual care Vts (10 ml/kg) from the initiation of mechanical ventilation in the operating room through Postoperative Day 3. The primary endpoint was the onset of reperfusion lung injury. Secondary outcomes included severity of hypoxemia, days on mechanical ventilation, and intensive care unit and hospital lengths of stay. A total of 128 patients were enrolled and included in the analysis; 63 were randomized to the low-Vt group and 65 were randomized to the usual care group. There was no statistically significant difference in the incidence of reperfusion lung injury between groups (32%, n=20 in the low-Vt group vs. 23%, n=15 in the usual care group; P=0.367). Although differences were noted in plateau pressures (17.9 cm H2O vs. 20.1 cm H2O, Plung injury or improve clinical outcomes. Clinical trial registered with (NCT00747045).

  13. Initiation of resuscitation with high tidal volumes causes cerebral hemodynamic disturbance, brain inflammation and injury in preterm lambs.

    Directory of Open Access Journals (Sweden)

    Graeme R Polglase

    Full Text Available AIMS: Preterm infants can be inadvertently exposed to high tidal volumes (V(T in the delivery room, causing lung inflammation and injury, but little is known about their effects on the brain. The aim of this study was to compare an initial 15 min of high V(T resuscitation strategy to a less injurious resuscitation strategy on cerebral haemodynamics, inflammation and injury. METHODS: Preterm lambs at 126 d gestation were surgically instrumented prior to receiving resuscitation with either: 1 High V(T targeting 10-12 mL/kg for the first 15 min (n = 6 or 2 a protective resuscitation strategy (Prot V(T, consisting of prophylactic surfactant, a 20 s sustained inflation and a lower initial V(T (7 mL/kg; n = 6. Both groups were subsequently ventilated with a V(T 7 mL/kg. Blood gases, arterial pressures and carotid blood flows were recorded. Cerebral blood volume and oxygenation were assessed using near infrared spectroscopy. The brain was collected for biochemical and histologic assessment of inflammation, injury, vascular extravasation, hemorrhage and oxidative injury. Unventilated controls (UVC; n = 6 were used for comparison. RESULTS: High V(T lambs had worse oxygenation and required greater ventilatory support than Prot V(T lambs. High V(T resulted in cerebral haemodynamic instability during the initial 15 min, adverse cerebral tissue oxygenation index and cerebral vasoparalysis. While both resuscitation strategies increased lung and brain inflammation and oxidative stress, High V(T resuscitation significantly amplified the effect (p = 0.014 and p<0.001. Vascular extravasation was evident in the brains of 60% of High V(T lambs, but not in UVC or Prot V(T lambs. CONCLUSION: High V(T resulted in greater cerebral haemodynamic instability, increased brain inflammation, oxidative stress and vascular extravasation than a Prot V(T strategy. The initiation of resuscitation targeting Prot V(T may reduce the severity of brain injury in preterm neonates.

  14. Tidal Volume and Instantaneous Respiration Rate Estimation using a Volumetric Surrogate Signal Acquired via a Smartphone Camera. (United States)

    Reyes, Bersain A; Reljin, Natasa; Kong, Youngsun; Nam, Yunyoung; Chon, Ki H


    Two parameters that a breathing status monitor should provide include tidal volume ( VT) and respiration rate (RR). Recently, we implemented an optical monitoring approach that tracks chest wall movements directly on a smartphone. In this paper, we explore the use of such noncontact optical monitoring to obtain a volumetric surrogate signal, via analysis of intensity changes in the video channels caused by the chest wall movements during breathing, in order to provide not only average RR but also information about VT and to track RR at each time instant (IRR). The algorithm, implemented on an Android smartphone, is used to analyze the video information from the smartphone's camera and provide in real time the chest movement signal from N = 15 healthy volunteers, each breathing at VT ranging from 300 mL to 3 L. These measurements are performed separately for each volunteer. Simultaneous recording of volume signals from a spirometer is regarded as reference. A highly linear relationship between peak-to-peak amplitude of the smartphone-acquired chest movement signal and spirometer VT is found ( r2 = 0.951 ±0.042, mean ± SD). After calibration on a subject-by-subject basis, no statistically significant bias is found in terms of VT estimation; the 95% limits of agreement are -0.348 to 0.376 L, and the root-mean-square error (RMSE) was 0.182 ±0.107 L. In terms of IRR estimation, a highly linear relation between smartphone estimates and the spirometer reference was found ( r2 = 0.999 ±0.002). The bias, 95% limits of agreement, and RMSE are -0.024 breaths-per-minute (bpm), -0.850 to 0.802 bpm, and 0.414 ±0.178 bpm, respectively. These promising results show the feasibility of developing an inexpensive and portable breathing monitor, which could provide information about IRR as well as VT, when calibrated on an individual basis, using smartphones. Further studies are required to enable practical implementation of the proposed approach.

  15. Variability in Tidal Volume Affects Lung and Cardiovascular Function Differentially in a Rat Model of Experimental Emphysema

    Directory of Open Access Journals (Sweden)

    Caio G. R. S. Wierzchon


    Full Text Available In experimental elastase-induced emphysema, mechanical ventilation with variable tidal volumes (VT set to 30% coefficient of variation (CV may result in more homogenous ventilation distribution, but might also impair right heart function. We hypothesized that a different CV setting could improve both lung and cardiovascular function. Therefore, we investigated the effects of different levels of VT variability on cardiorespiratory function, lung histology, and gene expression of biomarkers associated with inflammation, fibrogenesis, epithelial cell damage, and mechanical cell stress in this emphysema model. Wistar rats (n = 35 received repeated intratracheal instillation of porcine pancreatic elastase to induce emphysema. Seven animals were not ventilated and served as controls (NV. Twenty-eight animals were anesthetized and assigned to mechanical ventilation with a VT CV of 0% (BASELINE. After data collection, animals (n = 7/group were randomly allocated to VT CVs of 0% (VV0; 15% (VV15; 22.5% (VV22.5; or 30% (VV30. In all groups, mean VT was 6 mL/kg and positive end-expiratory pressure was 3 cmH2O. Respiratory system mechanics and cardiac function (by echocardiography were assessed continuously for 2 h (END. Lung histology and molecular biology were measured post-mortem. VV22.5 and VV30 decreased respiratory system elastance, while VV15 had no effect. VV0, VV15, and VV22.5, but not VV30, increased pulmonary acceleration time to pulmonary ejection time ratio. VV22.5 decreased the central moment of the mean linear intercept (D2 of Lm while increasing the homogeneity index (1/β compared to NV (77 ± 8 μm vs. 152 ± 45 μm; 0.85 ± 0.06 vs. 0.66 ± 0.13, p < 0.05 for both. Compared to NV, VV30 was associated with higher interleukin-6 expression. Cytokine-induced neutrophil chemoattractant-1 expression was higher in all groups, except VV22.5, compared to NV. IL-1β expression was lower in VV22.5 and VV30 compared to VV0. IL-10 expression was higher

  16. Acute Effects of Caffeine on Heart Rate Variability, Blood Pressure and Tidal Volume in Paraplegic and Tetraplegic Compared to Able-Bodied Individuals: A Randomized, Blinded Trial. (United States)

    Flueck, Joelle Leonie; Schaufelberger, Fabienne; Lienert, Martina; Schäfer Olstad, Daniela; Wilhelm, Matthias; Perret, Claudio


    Caffeine increases sympathetic nerve activity in healthy individuals. Such modulation of nervous system activity can be tracked by assessing the heart rate variability. This study aimed to investigate the influence of caffeine on time- and frequency-domain heart rate variability parameters, blood pressure and tidal volume in paraplegic and tetraplegic compared to able-bodied participants. Heart rate variability was measured in supine and sitting position pre and post ingestion of either placebo or 6 mg caffeine in 12 able-bodied, 9 paraplegic and 7 tetraplegic participants in a placebo-controlled, randomized and double-blind study design. Metronomic breathing was applied (0.25 Hz) and tidal volume was recorded during heart rate variability assessment. Blood pressure, plasma caffeine and epinephrine concentrations were analyzed pre and post ingestion. Most parameters of heart rate variability did not significantly change post caffeine ingestion compared to placebo. Tidal volume significantly increased post caffeine ingestion in able-bodied (p = 0.021) and paraplegic (p = 0.036) but not in tetraplegic participants (p = 0.34). Systolic and diastolic blood pressure increased significantly post caffeine in able-bodied (systolic: p = 0.003; diastolic: p = 0.021) and tetraplegic (systolic: p = 0.043; diastolic: p = 0.042) but not in paraplegic participants (systolic: p = 0.09; diastolic: p = 0.33). Plasma caffeine concentrations were significantly increased post caffeine ingestion in all three groups of participants (pcaffeine on the autonomic nervous system seems to depend on the level of lesion and the extent of the impairment. Therefore, tetraplegic participants may be less influenced by caffeine ingestion. NCT02083328.

  17. Pulse Pressure Variation Adjusted by Respiratory Changes in Pleural Pressure, Rather Than by Tidal Volume, Reliably Predicts Fluid Responsiveness in Patients With Acute Respiratory Distress Syndrome. (United States)

    Liu, Yang; Wei, Lu-qing; Li, Guo-qiang; Yu, Xin; Li, Guo-feng; Li, Yu-ming


    1) To evaluate the ability of pulse pressure variation adjusted by respiratory changes in pleural pressure to predict fluid responsiveness compared with pulse pressure variation alone. 2) To identify factors explaining the poor performance of pulse pressure variation in acute respiratory distress syndrome. Prospective study. Forty-bed university hospital general ICU. Ninety-six mechanically ventilated acute respiratory distress syndrome patients requiring fluid challenge. Fluid challenge, 500 mL saline over 20 minutes. Before fluid challenge, esophageal pressure was measured at the end-inspiratory and end-expiratory occlusions. Change in pleural pressure was calculated as the difference between esophageal pressure measured at end-inspiratory and end-expiratory occlusions. Hemodynamic measurements were obtained before and after the fluid challenge. Patients were ventilated with tidal volume 7.0 ± 0.8 mL/kg predicted body weight. The fluids increased cardiac output by greater than 15% in 52 patients (responders). Adjusting pulse pressure variation for changes in pleural pressure (area under the receiver operating characteristic curve, 0.94 [0.88-0.98]) and the ratio of chest wall elastance to total respiratory system elastance (area under the receiver operating characteristic curve, 0.93 [0.88-0.98]) predicted fluid responsiveness better than pulse pressure variation (area under the receiver operating characteristic curve, 0.78 [0.69-0.86]; all p variation/changes in pleural pressure values (1.94-2.1) in 3.1% of patients for whom fluid responsiveness could not be predicted reliably. On logistic regression analysis, two independent factors affected the correct classification of fluid responsiveness at a 12% pulse pressure variation cutoff: tidal volume (adjusted odds ratio 1.57/50 mL; 95% CI, 1.05-2.34; p = 0.027) and chest wall elastance/respiratory system elastance (adjusted odds ratio, 2.035/0.1 unit; 95% CI, 1.36-3.06; p = 0.001). In patients with chest wall

  18. Tidal Energy. (United States)

    Impact of Science on Society, 1987


    States that tidal power projects are feasible in a relatively limited number of locations around the world. Claims that together they could theoretically produce the energy equivalent to more than one million barrels of oil per year. (TW)

  19. Tidal power

    Energy Technology Data Exchange (ETDEWEB)

    Baker, A.C.


    The principal tidal power sites around the world are summarised, showing that the UK is fortunate in having three major potential sites. The first use of tidal power for generating electricity was a small scheme near Bristol built 56 years ago. Since then, the 240 MW Rance barrage and the recent 20 MW pilot 'Straflo' turbine installed at Annapolis Royal in the Bay of Funday are the main schemes built to date. These were built 'in the dry'. For an inlet off the White sea, North Russia, a samll tidal power plant was prefabricated complete and towed into position in the early 1960s. Alternative methods of operation are discussed and the economics of tidal power compared with thermal stations. Overall, the tides could be a highly predictable and substantial source of renewable energy whose development involves proven technology.

  20. Low tidal volume mechanical ventilation against no ventilation during cardiopulmonary bypass heart surgery (MECANO): study protocol for a randomized controlled trial. (United States)

    Nguyen, Lee S; Merzoug, Messaouda; Estagnasie, Philippe; Brusset, Alain; Law Koune, Jean-Dominique; Aubert, Stephane; Waldmann, Thierry; Grinda, Jean-Michel; Gibert, Hadrien; Squara, Pierre


    Postoperative pulmonary complications are a leading cause of morbidity and mortality after cardiac surgery. There are no recommendations on mechanical ventilation associated with cardiopulmonary bypass (CPB) during surgery and anesthesiologists perform either no ventilation (noV) at all during CPB or maintain low tidal volume (LTV) ventilation. Indirect evidence points towards better pulmonary outcomes when LTV is performed but no large-scale prospective trial has yet been published in cardiac surgery. The MECANO trial is a single-center, double-blind, randomized, controlled trial comparing two mechanical ventilation strategies, noV and LTV, during cardiac surgery with CPB. In total, 1500 patients are expected to be included, without any restrictions. They will be randomized between noV and LTV on a 1:1 ratio. The noV group will receive no ventilation during CPB. The LTV group will receive 5 breaths/minute with a tidal volume of 3 mL/kg and positive end-expiratory pressure of 5 cmH2O. The primary endpoint will be a composite of all-cause mortality, early respiratory failure defined as a ratio of partial pressure of oxygen/fraction of inspired oxygen ventilation, mechanical ventilation or high-flow oxygen) at 2 days after arrival in the ICU or ventilator-acquired pneumonia defined by the Center of Disease Control. Lung recruitment maneuvers will be performed in the noV and LTV groups at the end of surgery and at arrival in ICU with an insufflation at +30 cmH20 for 5 seconds. Secondary endpoints are those composing the primary endpoint with the addition of pneumothorax, CPB duration, quantity of postoperative bleeding, red blood cell transfusions, revision surgery requirements, length of stay in the ICU and in the hospital and total hospitalization costs. Patients will be followed until hospital discharge. The MECANO trial is the first of its kind to compare in a double-blind design, a no-ventilation to a low-tidal volume strategy for mechanical ventilation during

  1. Los Angeles and Long Beach Harbors Model Enhancement Program. Tidal Circulation Prototype Data Collection Effort. Volume 3. Appendix J (United States)


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  2. Mechanical ventilation with high tidal volumes attenuates myocardial dysfunction by decreasing cardiac edema in a rat model of LPS-induced peritonitis

    Directory of Open Access Journals (Sweden)

    Smeding Lonneke


    Full Text Available Abstract Background Injurious mechanical ventilation (MV may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis. Methods Normal rats and intraperitoneal (i.p. lipopolysaccharide (LPS-treated rats were ventilated with low (6 ml/kg and high (19 ml/kg tidal volumes (Vt under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP, central venous pressure (CVP, cardiac output (CO and pulmonary plateau pressure (Pplat were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM-1 and edema were measured to evaluate endothelial inflammation and leakage. Results MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo. Conclusion MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation.

  3. Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state (United States)

    A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes the bulk volume of sediment equates to the sum of self-packing volumes of organic and mineral components or BD =...

  4. Tides and tidal currents

    NARCIS (Netherlands)

    Roos, A.


    Basic phenomena, origin and generation of tides, analysis and prediction of tides, basic equation and types of long waves in one dimension, tidal propagation in one dimension, tidal propagation in two directions, analytical tidal computation, numerical tidal computation.

  5. [Positive end-expiratory pressure and tidal volume titration after recruitment maneuver in a canine model of acute respiratory distress syndrome]. (United States)

    Zhan, Qing-Yuan; Wang, Chen; Sun, Bing; Pang, Bao-sen


    To investigate the mechanisms of alveolar derecruitment and titration of positive end-expiratory pressure (PEEP) and tidal volume (V(T)) after recruitment maneuver (RM) in acute respiratory distress syndrome (ARDS). Eighteen dogs with oleic acid induced ARDS were ventilated with volume controlled ventilation [VCV, PEEP 16 cm H2O, V(T) 10 ml/kg, respiratory rate (RR) 30 breaths/min] and the steady state in this mode was defined as baseline (0 min). All animals accepted RM by using pressure controlled ventilation [PEEP 35 cm H2O and peak inspiratory pressure (PIP) 50 cm H2O for 1 min] and then randomly assigned into three groups and ventilated by VCV for 4 h: low V(T) and moderate PEEP group (LVMP group, V(T) 10 ml/kg, PEEP 16 cm H2O, RR 30 breaths/min), low V(T) and low PEEP group (LVLP group, V(T) 10 ml/kg, PEEP 10 cm H2O, RR 30 breaths/min) and moderate V(T) and low PEEP group (MVLP group, V(T) 15 ml/kg, PEEP 10 cm H2O, RR 20 breaths/min). Oxygenation, lung mechanics, hemodynamics and lung injury score were measured. (1) The average lower inflection pressure (LIP) was identified as (16.0 +/- 2.1) cm H2O. (2) PaO(2) in the LVMP group [(371 +/- 64) mm Hg at 30 min and (365 +/- 51) mm Hg at 60 min] was higher than that in the LVLP and the MVLP group [(243 +/- 112), (242 +/- 97) mm Hg at 30 min and (240 +/- 108), (232 +/- 87) mm Hg at 60 min, respectively; all P experiment. Better ventilation profiles were observed in the MVLP group. (3) Compared with baseline, marked cardiac compromise with higher airway plateau pressure (Pplat) and lower static respiratory compliance (Cst) were found in the LVMP group, while improvement was observed in other two groups. Cst in the MVLP group was slightly higher than that in the LVLP group. (4) No significant differences of lung injury were found from bronchoalveolar lavage fluid (BALF) analysis. Higher PEEP close to LIP maybe useful in preventing alveolar recollapse and improving oxygenation, but harmful to hemodynamics and may

  6. A Novel Prototype Neonatal Resuscitator That Controls Tidal Volume and Ventilation Rate: A Comparative Study of Mask Ventilation in a Newborn Manikin. (United States)

    Solevåg, Anne Lee; Haemmerle, Enrico; van Os, Sylvia; Bach, Katinka P; Cheung, Po-Yin; Schmölzer, Georg M


    The objective of this randomized controlled manikin trial was to examine tidal volume (VT) delivery and ventilation rate during mask positive pressure ventilation (PPV) with five different devices, including a volume-controlled prototype Next Step™ device for neonatal resuscitation. We hypothesized that VT and rate would be closest to target with the Next Step™. Twenty-five Neonatal Resuscitation Program providers provided mask PPV to a newborn manikin (simulated weight 1 kg) in a randomized order with a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone resuscitation system T-piece, and the Next Step™. All T-pieces used a peak inflation pressure of 20 cmH2O and a positive end-expiratory pressure of 5 cmH2O. The participants were instructed to deliver a 5 mL/kg VT (rate 40-60/min) for 1 min with each device and each of three test lungs with increasing compliance of 0.5, 1.0, and 2.0 mL/cmH2O. VT and ventilation rate were compared between devices and compliance levels (linear mixed model). All devices, except the Next Step™ delivered a too high VT, up to sixfold the target at the 2.0-mL/cmH2O compliance. The Next Step™ VT was 26% lower than the target in the low compliance. The ventilation rate was within target with the Next Step™ and SIB, and slightly lower with the T-pieces. In conclusion, routinely used newborn resuscitators over delivered VT, whereas the Next Step™ under delivered in the low compliant test lung. The SIB had higher VT and rate than the T-pieces. More research is needed on volume-controlled delivery room ventilation.

  7. A Novel Prototype Neonatal Resuscitator that Controls Tidal Volume and Ventilation Rate. A Comparative Study of Mask Ventilation in a Newborn Manikin

    Directory of Open Access Journals (Sweden)

    Anne Lee Solevåg


    Full Text Available The objective of this randomized controlled manikin trial was to examine tidal volume (VT delivery and ventilation rate during mask positive pressure ventilation (PPV with five different devices, including a volume-controlled prototype Next StepTM device for neonatal resuscitation. We hypothesized that VT and rate would be closest to target with the Next StepTM. Twenty-five Neonatal Resuscitation Program (NRP providers provided mask PPV to a newborn manikin (simulated weight 1kg in a randomized order with: a self-inflating bag (SIB, a disposable T-piece, a non-disposable T-piece, a stand-alone resuscitation system T-piece, and the Next StepTM. All T-pieces used a peak inflation pressure of 20cmH2O and a positive end-expiratory pressure of 5cmH2O. The participants were instructed to deliver a 5mL/kg VT (rate 40-60min-1 for 1min with each device and each of three test lungs with increasing compliance of 0.5, 1.0 and 2.0mL/cmH2O. VT and ventilation rate were compared between devices and compliance levels (linear mixed model. All devices, except the Next StepTM delivered a too high VT, up to six-fold the target at the 2.0mL/cmH2O compliance. The Next StepTM VT was 26% lower than the target in the low compliance. The ventilation rate was within target with the Next StepTM and SIB, and slightly lower with the T-pieces. In conclusion, routinely used newborn resuscitators over delivered VT, whereas the Next StepTM under delivered in the low compliant test lung. The SIB had higher VT and rate than the T-pieces. More research is needed on volume-controlled delivery room ventilation.

  8. Developments in tidal power (United States)

    Charlier, R. H.

    Successful, planned, and potential tidal power plants and sites are discussed. Units are in operation in France and Russia, with the French plant using reversible blade turbines being used as a design guide for plants in Argentina and Australia. The U.S. is studying the feasibility of a plant in Passamaquaddy Bay, and Canada is pursuing construction of a plant in the Bay of Fundy. The Severn River in Great Britain is receiving a site study, and over a hundred plants have been built as local power systems in China. Bulb-type turbines, which enhance the volume emptying and filling the retaining basin, are considered as the highest performing power unit. Simpler one-way flow turbines have been suggested as more economical to install. Governmental, institutional, and investor impediments to tidal power plant are explored.

  9. Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs

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    L Mousavi Seresht


    Full Text Available Background : Appropriate determination of tidal volume (VT is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW, which was estimated by measured height (HBW or demi-span based body weight (DBW. Materials and Methods : This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Results : Forty nine patients were studied. Demi-span based body weight and thus VT (DTV were lower than Height based body weight and VT (HTV (P = 0.028, in male patients (P = 0.005. Difference was observed in peak airway pressure (PAP and airway resistance (AR changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Conclusions : Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation.

  10. Genome-wide association analysis with gray matter volume as a quantitative phenotype in first-episode treatment-naïve patients with schizophrenia.

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    Qiang Wang

    Full Text Available Reduced Gray matter (GM volume is a core feature of schizophrenia. Mapping genes that is associated with the heritable disease-related phenotypes may be conducive to elucidate the pathogenesis of schizophrenia. This study aims to identify the common genetic variants that underlie the deficits of GM volume in schizophrenia. High-resolution T1 images and whole genome genotyping data were obtained from 74 first-episode treatment-naïve patients with schizophrenia and 51 healthy controls in the Mental Health Centre of the West China Hospital, Sichuan University. All participants were scanned using a 3T MR imaging system and were genotyped using the HumanHap660 Bead Array. Reduced GM volumes in three brain areas including right hOC3v in the collateral sulcus of visual cortex (hOC3vR, left cerebellar vermis lobule 10 (vermisL10 and right cerebellar vermis lobule 10 (vermisR10 were found in patients with schizophrenia [corrected].There was a group by genotype interaction when genotypes from genome-wide scan were subsequently considered in the case-control analyses. SNPs from three genes or chromosomal regions (TBXAS1, PIK3C2G and HS3ST5 were identified to predict the changes of GM volume in hOC3vL, vermisL10 and vermisR10. These results also highlighted the usefulness of endophenotype in exploring the pathogenesis of neuropsychiatric diseases such as schizophrenia although further independent replication studies are needed in the future.

  11. Expansibilidade torácica na avaliação do volume corrente em recém-nascidos prematuros ventilados Chest expansion for assessing tidal volume in premature newborn infants on ventilators

    Directory of Open Access Journals (Sweden)

    Ana Sílvia Scavacini


    Full Text Available OBJETIVOS: Avaliar se a observação clínica da expansibilidade torácica prediz o volume corrente em neonatos sob ventilação mecânica e se a experiência do examinador interfere no resultado. MÉTODOS: Estudo observacional que incluiu médicos de baixa experiência (1º ano de residência em pediatria, moderada experiência (2º ano de residência em pediatria, 1º ano de especialização em neonatologia ou em terapia intensiva pediátrica e experientes (2º ano de especialização em neonatologia, pós-graduandos ou assistentes com experiência mínima de 4 anos em neonatologia. Estes observaram a expansibilidade torácica de recém-nascidos em ventilação mecânica e responderam qual o volume corrente fornecido aos bebês. O volume corrente ofertado foi calculado, indexado ao peso atual do paciente e considerado adequado se entre 4-6 mL/kg, insuficiente se abaixo de 4 mL/kg e excessivo se acima de 6 mL/kg. Para análise dos resultados, foi utilizado o qui-quadrado. RESULTADOS: Foram realizadas 111 avaliações em 21 recém-nascidos, e as respostas fornecidas concordaram com o volume mensurado em 23,1, 41,3 e 65,7% para os médicos de baixa, moderada experiência e experientes, respectivamente. Esses resultados evidenciam que os três grupos não são estatisticamente iguais (p = 0,013 e que o grupo de médicos experientes apresenta maior concordância que os de baixa e moderada experiência (p = 0,007. CONCLUSÃO: A análise clínica da expansibilidade torácica realizada por médicos de baixa e moderada experiência apresenta pouca concordância com o volume corrente ofertado aos recém-nascidos em ventilação mecânica. Embora a experiência dos médicos tenha resultado em maior concordância, a expansibilidade torácica deve ser interpretada com cautela.OBJECTIVES: To investigate whether clinical observation of chest expansion predicts tidal volume in neonates on mechanical ventilation and whether observer experience interferes with

  12. Increasing compliance with low tidal volume ventilation in the ICU with two nudge-based interventions: evaluation through intervention time-series analyses. (United States)

    Bourdeaux, Christopher P; Thomas, Matthew Jc; Gould, Timothy H; Malhotra, Gaurav; Jarvstad, Andreas; Jones, Timothy; Gilchrist, Iain D


    Low tidal volume (TVe) ventilation improves outcomes for ventilated patients, and the majority of clinicians state they implement it. Unfortunately, most patients never receive low TVes. 'Nudges' influence decision-making with subtle cognitive mechanisms and are effective in many contexts. There have been few studies examining their impact on clinical decision-making. We investigated the impact of 2 interventions designed using principles from behavioural science on the deployment of low TVe ventilation in the intensive care unit (ICU). University Hospitals Bristol, a tertiary, mixed medical and surgical ICU with 20 beds, admitting over 1300 patients per year. Data were collected from 2144 consecutive patients receiving controlled mechanical ventilation for more than 1 hour between October 2010 and September 2014. Patients on controlled mechanical ventilation for more than 20 hours were included in the final analysis. (1) Default ventilator settings were adjusted to comply with low TVe targets from the initiation of ventilation unless actively changed by a clinician. (2) A large dashboard was deployed displaying TVes in the format mL/kg ideal body weight (IBW) with alerts when TVes were excessive. TVe in mL/kg IBW. TVe was significantly lower in the defaults group. In the dashboard intervention, TVe fell more quickly and by a greater amount after a TVe of 8 mL/kg IBW was breached when compared with controls. This effect improved in each subsequent year for 3 years. This study has demonstrated that adjustment of default ventilator settings and a dashboard with alerts for excessive TVe can significantly influence clinical decision-making. This offers a promising strategy to improve compliance with low TVe ventilation, and suggests that using insights from behavioural science has potential to improve the translation of evidence into practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please

  13. Enhanced functional connectivity and volume between cognitive and reward centers of naïve rodent brain produced by pro-dopaminergic agent KB220Z.

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    Marcelo Febo

    Full Text Available Dopaminergic reward dysfunction in addictive behaviors is well supported in the literature. There is evidence that alterations in synchronous neural activity between brain regions subserving reward and various cognitive functions may significantly contribute to substance-related disorders. This study presents the first evidence showing that a pro-dopaminergic nutraceutical (KB220Z significantly enhances, above placebo, functional connectivity between reward and cognitive brain areas in the rat. These include the nucleus accumbens, anterior cingulate gyrus, anterior thalamic nuclei, hippocampus, prelimbic and infralimbic loci. Significant functional connectivity, increased brain connectivity volume recruitment (potentially neuroplasticity, and dopaminergic functionality were found across the brain reward circuitry. Increases in functional connectivity were specific to these regions and were not broadly distributed across the brain. While these initial findings have been observed in drug naïve rodents, this robust, yet selective response implies clinical relevance for addicted individuals at risk for relapse, who show reductions in functional connectivity after protracted withdrawal. Future studies will evaluate KB220Z in animal models of addiction.

  14. Tidal power in Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Aisiks, E.G.


    This presentation describes the tidal power potential of Argentina and the current status of its utilization. The topics of the presentation include tidal power potential, electric production of the region and the Argentine share of production and consumption, conventional hydroelectric potential, economic feasibility of tidal power production, and the general design and feasibility of a tidal power plant planned for the San Jose Gulf.

  15. Efeitos de diferentes volumes correntes e da pressão expiratória final positiva sobre a troca gasosa na fístula broncopleural experimental Effects of different tidal volumes and positive end expiratory pressure on gas exchange in experimental bronchopleural fistula

    Directory of Open Access Journals (Sweden)

    Maria Gabriela Cavicchia Toneloto


    melhora e o débito da fístula é reduzido quando comparado ao volume corrente de 10ml/Kg. Um baixo volume resulta em hipercapnia e grave dessaturação. Finalmente, em qualquer volume corrente, PEEP aumenta o débito da fístula e diminui a ventilação alveolar.OBJECTIVES: The present study was designed to identify the effect of positive end expiratory pressure (PEEP and the ideal pulmonary tidal volume to ventilate animals with a surgically produced bronchopleural fistula, aiming to reduce fistula output without affecting gas exchange. METHODS: Hemodynamic and respiratory assessment of gas exchange was obtained in five, healthy, young, mechanically ventilated Large White pigs under volume controlled ventilation with FiO2 of 0.4 and an inspiration:expiration ratio of 1:2, keeping respiratory rate at 22 cpm. A bronchopleural fistula was produced by resection of the lingula. Underwater seal drainage was installed and the thorax was hermetically closed. Gas exchange and fistula output were measured with the animals ventilated sequentially with tidal volumes of 4 ml/kg, 7 ml/kg and 10 ml/Kg alternating zero of positive end expiratory pressure (ZEEP and PEEP of 10 cmH2O, always in the same order. RESULTS: These findings are attributed to reduced alveolar ventilation and ventilation/perfusion abnormalities and were attenuated with larger tidal volumes. PEEP increases air leak, even with low volume (of 2.0 ± 2.8mL to 31 ± 20.7mL; p= 0.006 and decreases alveolar ventilation in all tidal volumes. Alveolar ventilation improved with larger tidal volumes, but increased fistula output (10 mL/kg - 25.8 ± 18.3mL to 80.2 ± 43.9mL; p=0.0010. Low tidal volumes result in hypercapnia (ZEEP - Toneloto MGC, Terzi RGG, Silva WA, Moraes AC, Moreira MM 83.7± 6.9 mmHg and with PEEP 10 - 93 ± 10.1mmHg and severely decreased arterial oxygen saturation, about of 84%. CONCLUSIONS: The tidal volume of 7 ml/Kg with ZEEP was considered the best tidal volume because, despite moderate hypercapnia

  16. Tidal peritoneal dialysis: preliminary experience. (United States)

    Flanigan, M J; Doyle, C; Lim, V S; Ullrich, G


    To determine the feasibility of home tidal peritoneal dialysis (TPD) and to assess whether eight hours of TPD can achieve uremia control and urea removal equal to that of continuous cycling peritoneal dialysis (CCPD). An open enrollment pilot study. The Home Dialysis Training Center of the University of Iowa Hospitals and Clinics, a tertiary care teaching hospital. Nine patients experienced with CCPD and living 80 km to 280 km from the dialysis center began TPD, because they wished to decrease their dialysis time. Following baseline measurements, each patient was taught to perform TPD. TPD consisted of an initial fill volume of 40 mL/kg, a residual volume approximately 20 mL/kg, and tidal exchanges of 10 to 20 mL/kg to achieve the desired hourly flow rate. Clinic assessments took place every four to six weeks, and prescriptions were subsequently altered to attain urea removal equal to that of CCPD. Patient interviews were used to determine TPD acceptance. Prior to each clinic visit, dialysate effluent volume and dialysis duration were recorded, and a sterile sample of the effluent was obtained for urea, creatinine, and total nitrogen measurement. Urea and creatinine clearances increased with dialysate flow. Dialysate nonurea nitrogen was 3.0 +/- 0.2 mmol/kg/D and changed minimally with increasing dialysate volumes. Eight hours of TPD (initial fill: 40 mL/kg; residual volume: 20 mL/kg; tidal inflow: 20 mL/kg) with hourly tidal flow exceeding 40 mL/kg/hr and no daytime volume achieved urea removal equal to that of the patient's prior CCPD prescription. TPD can provide dialysis equal to that of CCPD within a shorter amount of time (eight vs ten hours), but uses a greater volume of dialysate (16.0 L for TPD vs 9.5 L for CCPD).

  17. Preliminary study of ventilation with 4 ml/kg tidal volume in acute respiratory distress syndrome: feasibility and effects on cyclic recruitment - derecruitment and hyperinflation. (United States)

    Retamal, Jaime; Libuy, Javiera; Jiménez, Magdalena; Delgado, Matías; Besa, Cecilia; Bugedo, Guillermo; Bruhn, Alejandro


    Cyclic recruitment-derecruitment and overdistension contribute to ventilator-induced lung injury. Tidal volume (Vt) may influence both, cyclic recruitment-derecruitment and overdistension. The goal of this study was to determine if decreasing Vt from 6 to 4 ml/kg reduces cyclic recruitment-derecruitment and hyperinflation, and if it is possible to avoid severe hypercapnia. Patients with pulmonary acute respiratory distress syndrome (ARDS) were included in a crossover study with two Vt levels: 6 and 4 ml/kg. The protocol had two parts: one bedside and other at the CT room. To avoid severe hypercapnia in the 4 ml/kg arm, we replaced the heat and moisture exchange filter by a heated humidifier, and respiratory rate was increased to keep minute ventilation constant. Data on lung mechanics and gas exchange were taken at baseline and after 30 minutes at each Vt (bedside). Thereafter, a dynamic CT (4 images/sec for 8 sec) was taken at each Vt at a fixed transverse region between the middle and lower third of the lungs. Afterward, CT images were analyzed and cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration, and hyperinflation as maximal hyperinflated tissue at end-inspiration, expressed as % of lung tissue weight. We analyzed 10 patients. Decreasing Vt from 6 to 4 ml/kg consistently decreased cyclic recruitment-derecruitment from 3.6 (2.5 to 5.7) % to 2.9 (0.9 to 4.7) % (P <0.01) and end-inspiratory hyperinflation from 0.7 (0.3 to 2.2) to 0.6 (0.2 to 1.7) % (P = 0.01). No patient developed severe respiratory acidosis or severe hypercapnia when decreasing Vt to 4 ml/kg (pH 7.29 (7.21 to 7.46); PaCO2 48 (26 to 51) mmHg). Decreasing Vt from 6 to 4 ml/kg reduces cyclic recruitment-derecruitment and hyperinflation. Severe respiratory acidosis may be effectively prevented by decreasing instrumental dead space and by increasing respiratory rate.

  18. Tidal Energy Update 2009


    O'Rourke, Fergal; Boyle, Fergal; Reynolds, Anthony


    Tidal energy has the potential to play a valuable part in a sustainable energy future. It is an extremely predictable energy source, depending only on the gravitational pull of the moon and the sun and the centrifugal forces created by the rotation of the earth-moon system. Tidal energy has been exploited on a significant scale since the construction of the La Rance tidal barrage in France in 1967. A tidal barrage utilises the potential energy of the tide and has proven to be very successful,...


    Energy Technology Data Exchange (ETDEWEB)

    Dobos, Vera [Konkoly Thege Miklos Astronomical Institute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Konkoly Thege Miklós út 15-17, Budapest (Hungary); Turner, Edwin L., E-mail: [Department of Astrophysical Sciences, Princeton University, 08544, 4 Ivy Lane, Peyton Hall, Princeton, NJ (United States)


    Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life has been intensely studied on solar system moons such as Europa or Enceladus where the surface ice layer covers a tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. To study the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than the widely used, so-called fixed Q models because it takes into account the temperature dependence of the tidal heat flux and the melting of the inner material. Using this model, we introduced the circumplanetary Tidal Temperate Zone (TTZ), which strongly depends on the orbital period of the moon and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ using both models. We have found that the viscoelastic model predicts 2.8 times more exomoons in the TTZ with orbital periods between 0.1 and 3.5 days than the fixed Q model for plausible distributions of physical and orbital parameters. The viscoelastic model provides more promising results in terms of habitability because the inner melting of the body moderates the surface temperature, acting like a thermostat.

  20. The effects of tidal range on saltmarsh morphology (United States)

    Goodwin, Guillaume; Mudd, Simon


    Saltmarshes are highly productive coastal ecosystems that act simultaneously as flood barriers, carbon storage, pollutant filters and nurseries. As halophytic plants trap suspended sediment and decay in the settled strata, innervated platforms emerge from the neighbouring tidal flats, forming sub-vertical scarps on their eroding borders and sub-horizontal pioneer zones in areas of seasonal expansion. These evolutions are subject to two contrasting influences: stochastically generated waves erode scarps and scour tidal flats, whereas tidally-generated currents transport sediment to and from the marsh through the channel network. Hence, the relative power of waves and tidal currents strongly influences saltmarsh evolution, and regional variations in tidal range yield marshes of differing morphologies. We analyse several sheltered saltmarshes to determine how their morphology reflects variations in tidal forcing. Using tidal, topographic and spectral data, we implement an algorithm based on the open-source software LSDTopoTools to automatically identify features such as marsh platforms, tidal flats, erosion scarps, pioneer zones and tidal channels on local Digital Elevation Models. Normalised geometric properties are then computed and compared throughout the spectrum of tidal range, highlighting a notable effect on channel networks, platform geometry and wave exposure. We observe that micro-tidal marshes typically display jagged outlines and multiple islands along with wide, shallow channels. As tidal range increases, we note the progressive disappearance of marsh islands and linearization of scarps, both indicative of higher hydrodynamic stress, along with a structuration of channel networks and the increase of levee volume, suggesting higher sediment input on the platform. Future research will lead to observing and modelling the evolution of saltmarshes under various tidal forcing in order to assess their resilience to environmental change.

  1. Tidal viscosity of Enceladus (United States)

    Efroimsky, Michael


    In the preceding paper (Efroimsky, 2017), we derived an expression for the tidal dissipation rate in a homogeneous near-spherical Maxwell body librating in longitude. Now, by equating this expression to the outgoing energy flux due to the vapour plumes, we estimate the mean tidal viscosity of Enceladus, under the assumption that the Enceladean mantle behaviour is Maxwell. This method yields a value of 0.24 × 1014 Pa s for the mean tidal viscosity, which is very close to the viscosity of ice near the melting point.

  2. Grey matter volumes in treatment naïve vs. chronically treated children with attention deficit/hyperactivity disorder: a combined approach. (United States)

    Villemonteix, Thomas; De Brito, Stéphane A; Kavec, Martin; Balériaux, Danielle; Metens, Thierry; Slama, Hichem; Baijot, Simon; Mary, Alison; Peigneux, Philippe; Massat, Isabelle


    Psychostimulants are the first-line treatment in attention deficit/hyperactivity disorder (ADHD), but their effects on brain development remain poorly understood. In particular, previous structural magnetic resonance imaging (sMRI) studies only investigated treatment effects on grey matter (GM) volumes in selected regions of interest (ROIs). In this study, voxel-based morphometry (VBM) was used to assess medication-related GM volume differences across the entire brain. Automated tracing measurements of selected ROIs were also obtained. Three groups (77 participants aged 7-to-13 year old) underwent MRI scans and were compared: never-medicated children with ADHD (n=33), medicated (methylphenidate) children with ADHD (n=20) and typically developing children (TD; n=24). Optimised VBM was used to investigate regional GM volumes, controlling for age and gender. Automated tracing procedures were also used to assess the average volume of the caudate nucleus, the amygdala and the nucleus accumbens. When compared to both medicated children with ADHD and TD children, never-medicated children with ADHD exhibited decreased GM volume in the insula and in the middle temporal gyrus. When compared to TD children, medicated children with ADHD had decreased GM volume in the middle frontal gyrus and in the precentral gyrus. Finally, ROI analyses revealed a significant association between duration of treatment and GM volume of the left nucleus accumbens in medicated children with ADHD. In conclusion, this study documents potential methylphenidate-related GM volume normalization and deviation in previously unexplored brain structures, and reports a positive association between treatment history and GM volume in the nucleus accumbens, a key region for reward-processing. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  3. Tidal alignment of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš


    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used "nonlinear alignment model," finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the "GI" term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  4. Sustainable tidal power

    Energy Technology Data Exchange (ETDEWEB)

    Walsum, E. van


    North America is increasingly searching for ways to achieve energy self-sufficiency. This paper discussed the tidal power potential of the Upper Bay of Fundy, located on Canada's east coast. The Bay of Fundy has the largest tides in the world. It is also close to a major electricity market. Tidal power plants could mean substantial quantities of clean, renewable energy. Some of the environmental concerns with the development of tidal power plants on the Bay of Fundy include: siltation, shorebird survival, fish-stock survival, sea-mammal survival, drainage of agricultural lands, and changes in the tidal regime of the Bay of Fundy-Gulf of Maine Basin. In this paper, the author proved that it is possible to qualitatively assess those concerns, but that the quantitative assessment is more complex. A quantitative assessment of the effect on living organisms would require assessing the overall performance of an ecologically designed, built and operated pilot tidal power plant. The author argued that a full-fledged tidal power plant construction can take place once a pilot plant has been proven to operate symbiotically with a thriving marine shore-based flora and fauna. 18 refs., 2 tabs., 6 figs.

  5. Medida da freqüência respiratória e do volume corrente para prever a falha na extubação de recém-nascidos de muito baixo peso em ventilação mecânica Evaluation of respiratory rate and tidal volume to predict extubation failure in mechanically ventilated very low birth weight infants

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    Josy Davidson


    Full Text Available OBJETIVO: Verificar se a freqüência respiratória (FR, o volume corrente (VC e a relação FR/VC poderiam prever a falha na extubação em recém-nascidos de muito baixo peso submetidos à ventilação mecânica. MÉTODOS: Estudo prospectivo, observacional, de recém-nascidos com idade gestacional OBJECTIVE: To verify if respiratory rate (RR, tidal volume (TV and respiratory rate and tidal volume ratio (RR/TV could predict extubation failure in very low birth weight infants submitted to mechanical ventilation. METHODS: This prospective observational study enrolled newborn infants with gestational age <37 weeks and birth weight <1,500g, mechanically ventilated from birth during 48 hours to 30 days and thought to be ready for extubation. As soon as the physicians decided for extubation, the neonates received endotracheal continuous positive airway pressure (CPAP for 10 minutes while spontaneous RR, TV and RR/TV were measured using a fixed-orifice pneumotachograph positioned between the endotracheal tube and the ventilator circuit. Thereafter, the neonates were extubated to nasal CPAP. Extubation failure was defined as the need for reintubation within 48 hours. RESULTS: Of the 35 studied infants, 20 (57% were successfully extubated and 15 (43% required reintubation. RR and RR/TV before extubation had a trend to be higher in unsuccessfully extubated infants. TV was similar in both groups. Sensitivity and specificity of these parameters as predictors of extubation failure were 50 and 67% respectively for RR, 40 and 67% for TV and 40 and 73% for RR/TV. CONCLUSIONS: RR, TV and RR/TV showed low sensitivity and specificity to predict extubation failure in mechanically ventilated very low birth weight infants.

  6. Hareketli Heykel ve Dans


    RUIZ, Manuel Adsuara


    Heykel tarihinin ve anlamının içinden bir yolculukta hareketli heykel ve dans…Dans gibi hareketler ve dansın kinetik değeri, heykelin birden fazla bakış açısı ile yapmacıklıktan beri, birliği kırıyoruz ve çok küçük bir bakış açısı değişikliği ile şekil değişikliğine ulaşıyoruz, başka bir değişle, bir balonun bir kesiti gibi. Hatta mimari bile, uzay, ışık, gölge ve yanlış perspektifleri(bakış açıları) ile yeni, göz kamaştırıcı ve teatral bir hareket ve görüş açısı sunuyor. Bu bize, heykele yük...

  7. Tidal power plants in Russia

    Energy Technology Data Exchange (ETDEWEB)

    Bernshtein, L.B. (Hydroproject Assoc., Moscow (Russian Federation))


    This article examines the performance of tidal power plants in Russia and the expansion of tidal plant to new sites. The topics of the article include remote construction and transport techniques, pilot plant performance, economics and payback, and a review of global tidal power plant designs that are on hold due to economic problems relating to the global economy.

  8. Effects of fresh gas flow, tidal volume, and charcoal filters on the washout of sevoflurane from the Datex Ohmeda (GE) Aisys, Aestiva/5, and Excel 210 SE Anesthesia Workstations. (United States)

    Sabouri, A Sassan; Lerman, Jerrold; Heard, Christopher


    We investigated the effects of tidal volume (VT), fresh gas flow (FGF), and a charcoal filter in the inspiratory limb on the washout of sevoflurane from the following Datex Ohmeda (GE) Anesthesia Workstations (AWSs): Aisys, Aestiva/5, and Excel 210SE. After equilibrating the AWSs with 2% sevoflurane, the anesthetic was discontinued, and the absorbent anesthesia breathing circuit (ABC), reservoir bag, and test lung were changed. The lung was ventilated with 350 or 200 mL·breath(-1), 15 breaths·min(-1), and a FGF of 10 L·min(-1) while the washout of sevoflurane was performed in triplicate using a calibrated Datex Ohmeda Capnomac Ultima™ and a calibrated MIRAN SapphIRe XL ambient air analyzer until the concentration was ≤ 10 parts per million (ppm). The effects of decreasing the FGF to 5 and 2 L·min(-1) after the initial washout and of a charcoal filter in the ABC were recorded separately. The median washout times with the Aisys AWS (14 min, P Excel 210SE (32 min). The mean (95% confidence interval) washout time with the Aisys increased to 23.5 (21.5 to 25.5) min with VT 200 mL·breath(-1) (P < 0.01). Decreasing the FGF from 10 to 5 and 2 L·min(-1) with the Aisys caused a rebound in sevoflurane concentration to ≥ 50 ppm. Placement of a charcoal filter in the inspiratory limb reduced the sevoflurane concentration to < 2 ppm in the Aisys and Aestiva/5 AWSs within two minutes. The GE AWSs should be purged with large FGFs and VTs ~350 mL·breath(-1) for ~25 min to achieve 10 ppm sevoflurane. The FGF should be maintained to avoid a rebound in anesthetic concentration. Charcoal filters rapidly decrease the anesthetic concentration to < 2 ppm.

  9. High tidal volume mechanical ventilation-induced lung injury in rats is greater after acid instillation than after sepsis-induced acute lung injury, but does not increase systemic inflammation: an experimental study

    Directory of Open Access Journals (Sweden)

    Kuiper Jan


    Full Text Available Abstract Background To examine whether acute lung injury from direct and indirect origins differ in susceptibility to ventilator-induced lung injury (VILI and resultant systemic inflammatory responses. Methods Rats were challenged by acid instillation or 24 h of sepsis induced by cecal ligation and puncture, followed by mechanical ventilation (MV with either a low tidal volume (Vt of 6 mL/kg and 5 cm H2O positive end-expiratory pressure (PEEP; LVt acid, LVt sepsis or with a high Vt of 15 mL/kg and no PEEP (HVt acid, HVt sepsis. Rats sacrificed immediately after acid instillation and non-ventilated septic animals served as controls. Hemodynamic and respiratory variables were monitored. After 4 h, lung wet to dry (W/D weight ratios, histological lung injury and plasma mediator concentrations were measured. Results Oxygenation and lung compliance decreased after acid instillation as compared to sepsis. Additionally, W/D weight ratios and histological lung injury scores increased after acid instillation as compared to sepsis. MV increased W/D weight ratio and lung injury score, however this effect was mainly attributable to HVt ventilation after acid instillation. Similarly, effects of HVt on oxygenation were only observed after acid instillation. HVt during sepsis did not further affect oxygenation, compliance, W/D weight ratio or lung injury score. Plasma interleukin-6 and tumour necrosis factor-α concentrations were increased after acid instillation as compared to sepsis, but plasma intercellular adhesion molecule-1 concentration increased during sepsis only. In contrast to lung injury parameters, no additional effects of HVt MV after acid instillation on plasma mediator concentrations were observed. Conclusions During MV more severe lung injury develops after acid instillation as compared to sepsis. HVt causes VILI after acid instillation, but not during sepsis. However, this differential effect was not observed in the systemic release of

  10. Tidal and subtidal hydrodynamics and energetics in a constricted estuary (United States)

    Zarzuelo, Carmen; López-Ruiz, Alejandro; Díez-Minguito, Manuel; Ortega-Sánchez, Miguel


    The dynamics of coastal plain estuaries are mainly associated with variable tidal forcing and local winds in combination with bathymetric complexity and coastline irregularity. Specific features, such as constricted areas, can potentially affect and energize the hydrodynamics of these types of systems. Particularly, tidal range and tidal currents can be significantly amplified where the incoming tidal wave becomes constricted. In this work, the impact of a narrow constriction on a mesotidal estuary was analysed at tidal and subtidal time scales. Tidal hydrodynamics, energy fluxes and energy dissipation were determined for the entire Cádiz Bay (southwestern Spain) using the Delft3D numerical model. Field observations were used to analyse tidal propagation and energy dissipation along the bay constriction and to calibrate and test the numerical model. The results indicate that the presence of the constriction transformed and distorted the tide and increased the tidal range and flow velocities along the channel, with implications on energy dissipation. The tidal currents were oriented along-channel at the central part of the constriction, although abrupt bathymetric changes at the channel inner boundary provoked a sudden rotation of the flow. Although the energy fluxes were higher for spring tides and were strongly influenced by winds, the energy dissipation was controlled by bed shear stresses and vertical dispersion. The significance of this energy dissipation was that it destabilized the water column, which resulted in a weakly stratified system with implications on water quality. At a subtidal scale, the residual water volume exchange was the result of the combined effects of the neap/spring tides, wind and waves, whereas tides were dominant at the tidal scale.

  11. The Effects of Preoperative Volume Replacement in Diabetic Patients Undergoing Coronary Artery Bypass Grafting Surgery: Protocol for a Randomized Controlled Trial (VeRDiCT Trial). (United States)

    Clout, Madeleine; Harris, Tracy; Rogers, Chris; Culliford, Lucy; Taylor, Jodi; Angelini, Gianni; Narayan, Pradeep; Reeves, Barnaby; Hillier, James; Ashton, Kate; Sarkar, Kunal; Ascione, Raimondo


    Diabetes mellitus is a major risk factor for prolonged hospital stays, renal failure, and mortality in patients having coronary artery bypass grafting (CABG). Complications pose a serious threat to patients and prolong intensive care and hospital stays. Low glomerular filtration rate (GFR) due to existing renal impairment or volume depletion may exacerbate acute renal impairment/failure in these patients. Preoperative volume replacement therapy (VRT) is reported to increase the GFR and we hypothesize that VRT will reduce renal impairment and related complications in diabetic patients. The objective of this study is to establish the efficacy of preoperative VRT in reducing postoperative complications in diabetic patients undergoing CABG surgery. Time to "fit for discharge", incidence of postoperative renal failure, cardiac injury, inflammation, and other health outcomes will be investigated. In this open parallel group randomized controlled trial, 170 diabetic patients undergoing elective or urgent CABG surgery received 1 mL/kg/hour of Hartmann's solution for 12 consecutive hours prior to surgery, versus routine care. The primary outcome was time until participants were "fit for discharge", which is defined as presence of: normal temperature, pulse, and respiration; normal oxygen saturation on air; normal bowel function; and physical mobility. Secondary outcomes included: incidence of renal failure; markers of renal function, inflammation, and cardiac damage; operative morbidity; intensive care stay; patient-assessed outcome, including the Coronary Revascularization Outcome Questionnaire; and use of hospital resources. Recruitment started in July 2010. Enrolment for the study was completed in July 2014. Data analysis commenced in December 2016. Study results will be submitted for publication in the summer of 2017. VRT is a relatively easy treatment to administer in patients undergoing surgical procedures who are at risk of renal failure. This experimental protocol

  12. Relativistic tidal disruption events

    Directory of Open Access Journals (Sweden)

    Levan A.


    Full Text Available In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s−1 at peak, rapid X-ray variability (factors of >100 on timescales of 100 seconds and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ∼ 2 − 5, created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  13. Dissipation of Tidal Energy (United States)


    The moon's gravity imparts tremendous energy to the Earth, raising tides throughout the global oceans. What happens to all this energy? This question has been pondered by scientists for over 200 years, and has consequences ranging from the history of the moon to the mixing of the oceans. Richard Ray at NASA's Goddard Space Flight Center, Greenbelt, Md. and Gary Egbert of the College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Ore. studied six years of altimeter data from the TOPEX/Poseidon satellite to address this question. According to their report in the June 15 issue of Nature, about 1 terawatt, or 25 to 30 percent of the total tidal energy dissipation, occurs in the deep ocean. The remainder occurs in shallow seas, such as on the Patagonian Shelf. 'By measuring sea level with the TOPEX/Poseidon satellite altimeter, our knowledge of the tides in the global ocean has been remarkably improved,' said Richard Ray, a geophysicist at Goddard. The accuracies are now so high that this data can be used to map empirically the tidal energy dissipation. (Red areas, above) The deep-water tidal dissipation occurs generally near rugged bottom topography (seamounts and mid-ocean ridges). 'The observed pattern of deep-ocean dissipation is consistent with topographic scattering of tidal energy into internal motions within the water column, resulting in localized turbulence and mixing', said Gary Egbert an associate professor at OSU. One important implication of this finding concerns the possible energy sources needed to maintain the ocean's large-scale 'conveyor-belt' circulation and to mix upper ocean heat into the abyssal depths. It is thought that 2 terawatts are required for this process. The winds supply about 1 terawatt, and there has been speculation that the tides, by pumping energy into vertical water motions, supply the remainder. However, all current general circulation models of the oceans ignore the tides. 'It is possible that properly

  14. Alternative concept for tidal power plant with reservoir restrictions

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Rafael M.; Estefen, Segen F. [Department of Ocean Engineering, COPPE/Federal University of Rio de Janeiro, P.O. Box 68508, 21945-970 Rio de Janeiro, RJ (Brazil)


    The Brazilian North and Northeast regions have possibilities on harnessing tidal power, where the greatest tidal amplitudes are to be found. In the 1970s, a barrage constructed in the Bacanga estuary, a civil construction project for reducing the distance between the city of Sao Luis do Maranhao and the port of Itaqui, was planned to be the first Brazilian tidal power plant. The favorable conditions associated with the considerable tidal heights, which can be as much as 6.5 m, made this an ideal place for building a pilot plant. Although, a scheme had been proposed to harness tidal energy in a conventional way with the use of the reservoir, the tidal plant in its original form was not implemented due economic and technical restrictions originated from the turbo generators chosen at that time. This paper presents an alternative concept for tidal power plant when the reservoir presents limitations caused by urban occupation, silting up and deterioration of the original structures. These limitations have been verified following the construction of the Bacanga barrage which led to an alternative proposal for the future installation of a pilot tidal power plant. The power generation possible to be harnessed was simulated through a model for each hour from the water head data, outflow, levels, areas and volumes of the reservoir and estuary. The development of the conceptual project, with the utilization of low-head turbines, a floating platform for the turbines and, particularly, taking into consideration those restrictions to be found at the present time, it can be concluded that Bacanga tidal power plant of is technically viable. (author)

  15. Kupa Tedavisi ve Hacamat


    Okumuş, Müyesser


    Antik çağlardan bu yana, tamamlayıcı ve geleneksel tedavi, insan sağlığı için önemli bir rol oynamıştır. Tamamlayıcı ve geleneksel tedavi uygulamalarından olan kupa (yaş veya kuru kupa tedavisi) tedavisi konvansiyonel tedaviye cevap vermeyen birçok bozukluklarda terapötik etkiye sahip olduğu iddia edilmektedir. Bu derleme, ilgili literatürün ışığında kupa tedavisi tanımlamasını, tarihçesini, uygulama tekniklerini, mekanizmasını, uygulama bölgelerini ve yan etkilerini özetlemektedir....

  16. Tidal Venuses: triggering a climate catastrophe via tidal heating. (United States)

    Barnes, Rory; Mullins, Kristina; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, René


    Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high-enough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets "Tidal Venuses" and the phenomenon a "tidal greenhouse." Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with masseswater via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.

  17. Tidal Energy Research

    Energy Technology Data Exchange (ETDEWEB)

    Stelzenmuller, Nickolas [Univ of Washington; Aliseda, Alberto [Univ of Washington; Palodichuk, Michael [Univ of Washington; Polagye, Brian [Univ of Washington; Thomson, James [Univ of Washington; Chime, Arshiya [Univ of Washington; Malte, Philip [Univ of washington


    This technical report contains results on the following topics: 1) Testing and analysis of sub-scale hydro-kinetic turbines in a flume, including the design and fabrication of the instrumented turbines. 2) Field measurements and analysis of the tidal energy resource and at a site in northern Puget Sound, that is being examined for turbine installation. 3) Conceptual design and performance analysis of hydro-kinetic turbines operating at high blockage ratio, for use for power generation and flow control in open channel flows.

  18. Excess molar volumes, and refractive index of binary mixtures of ...

    African Journals Online (AJOL)

    Excess molar volumes (VE) viscosities and refractive index have been evaluated for binary mixtures of glycerol + water, and glycerol + methanol at 298.15 K and 303.15 K. Excess molar volumes (VE) have been calculated from density. The excess molar volume (VE) results were fitted to the Redlich and Kister type ...

  19. Salinity structure of a tidal freshwater ecosystem under multiple tidal conditions, Mission River, TX, USA (United States)

    Jones, A.; Befus, K. M.; Cardenas, M.; McClelland, J. W.; Moffett, K. B.


    The ecological health and integrity of coastal estuaries critically depends on the balance between the quantity, quality, and timing of freshwater inflow. This balance may be upset by subtle changes in numerous hydrologic conditions, including precipitation rates and frequencies, runoff conditions, and tides. Certain hydrologic conditions will create an abnormally long freshwater residence time in a lower river reach--on the order of months between episodic storms--which will drastically alter the quantity, quality, and timing of estuarine freshwater inflow. We term this fresh, tidal, lentic river reach the 'tidal freshwater ecosystem' (TFE) and find that it remains largely overlooked by hydrologic and estuarine sciences. We hypothesize that TFEs occur in coastal rivers with small bed slope and riverine discharge, enabling denser saltwater intruding inland via tidal motion to impede freshwater discharge to the estuary. However, the balance of forces governing the relative rates and volumes of freshwater discharge, saltwater intrusion, and freshwater-saltwater mixing are not well understood in TFEs, especially with regard to the influence of vertical salinity structure (whether stratified, well-mixed, or a combination) on the retardation of freshwater discharge. In this study we sought to empirically characterize the salinity structure of a river known to contain a tidal freshwater reach, the Mission River of southern Texas. During high and low spring and neap tides, we surveyed a ~ 22 km-long tidal section of the river by towing two instruments: a multi-parameter probe measuring temperature, electrical conductivity (EC), and dissolved oxygen (DO) at mid-channel depth; and, at the water surface, an electrical resistivity geophysical cable measuring water and channel bed sediment electrical resistivity. We also profiled the water column every 0.25 km using a second multi-parameter probe. The data successfully resolved longitudinal and vertical salinity variations

  20. Tidal Power Exploitation in Korea (United States)

    Choi, Byung Ho; Kim, Kyeong Ok; Choi, Jae Cheon

    The highest tides in South Korea are found along the northwest coast between latitudes 36-38 degrees and the number of possible sites for tidal range power barrages to create tidal basins is great due to irregular coastlines with numerous bays. At present Lake Sihwa tidal power plant is completed. The plant is consisted of 10 bulb type turbines with 8 sluice gates. The installed capacity of turbines and generators is 254MW and annual energy output expected is about 552.7 GWh taking flood flow generation scheme. Three other TPP projects are being progressed at Garolim Bay (20 turbines with 25.4MW capacity), Kangwha (28 turbines with 25.4MW capacity), Incheon (44 or 48 turbines with 30 MW capacity) and project features will be outlined here. The introduction of tidal barrages into four major TPP projects along the Kyeonggi bay will render wide range of potential impacts. Preliminary attempts were performed to quantify these impacts using 2 D hydrodynamic model demonstrating the changes in tidal amplitude and phase under mean tidal condition, associated changes in residual circulation (indicator for SPM and pollutant dispersion), bottom stress (indicator for bedload movement), and tidal front (positional indicator for bio-productivity) in both shelf scale and local context. Tidal regime modeling system for ocean tides in the seas bordering the Korean Peninsula is designed to cover an area that is broad in scope and size, yet provide a high degree of resolution in strong tidal current region including off southwestern tip of the Peninsula (Uldolmok , Jangjuk, Wando-Hoenggan), Daebang Sudo (Channel) and Kyeonggi Bay. With this simulation system, real tidal time simulation of extended springneap cycles was performed to estimate spatial distribution of tidal current power potentials in terms of power density, energy density and then extrapolated annual energy density.

  1. Patterns of fracture and tidal stresses on Europa (United States)

    Helfenstein, P.; Parmentier, E. M.


    A comparison of dark band, triple band, and cuspate ridge orientations with the fracture patterns predicted for tidal distortion due to orbital recession and eccentricity is undertaken, to test the hypothesized identification of Europa's lineaments as tidal distortion and planetary volume change fractures. Short, reticule dark bands near the anti-Jove point could be tension cracks caused by orbital eccentricity. Long, arcuate dark bands and triple bands peripheral to the anti-Jove point may be strike-slip faults due to orbital recession. The orientation and distribution of cuspate ridges, if they are compressional, suggests their formation in response to a combination of orbital recession and planetary volume decrease. If surface fracturing is due to tidal deformation, important constraints are exerted by it on Europa's orbital evolution.

  2. DTP: a Tidal Power Revolution (United States)

    Steijn, Robbert; Hulsbergen, Kees; van Banning, Gijs


    Tidal power can significantly contribute to the global mix of sustainable energy resources. It is climate-independent, fully predictable, and if designed properly it is environmentally friendly and socio-economically feasible. The two traditional methods of exploiting tidal power are Tidal Barrage and Tidal Stream. This study deals with an alternative Third Method, named Dynamic Tidal Power (DTP), which contrary to the other methods, utilises the oscillating character of tides, or more precisely: the acceleration inherent to unsteady flow. DTP uses a long dam (order of tens of km's), attached and perpendicular to a coast with shore-parallel tidal currents, to generate a local hydraulic head. This time-varying head is used to generate electricity in a more or less standard way with turbines and generators placed in (many) dam openings. For a first impression only: typical installed power for one DTP is more than 10 GW with electricity output > 2.1010 kWh/y and construction costs of ca. 1 EUR/W. The physical mechanism behind the creation of the head has been described by Hulsbergen e.a., (2012). Following a heuristic approach based on analytical work done by Kolkman (unpubl.), and output from numerical tidal models, Hulsbergen (2012) concluded that the maximum head (near the coast), is: hmax = 6,8*?*D*Vmax/(g*T), with Vmax the maximum alongshore flow velocity during the tidal cycle, T the tidal period and D the length of dam. Such simple relationship was also found by Mei (2012) who made a rigorous analysis of a process-based model. After a thorough reflection on DTP, this study will first check the above formula for hmax , by comparing its predictions with the output from various numerical tidal models. Any differences will be analysed in the study through an evaluation of the dominant physical processes and the schematisations inherent to both the analytical and the numerical models. The study will also address the effect of the openings in the dam, as well as the

  3. Tidal Heating in Multilayered Terrestrial Exoplanets (United States)

    Henning, Wade G.; Hurford, Terry


    The internal pattern and overall magnitude of tidal heating for spin-synchronous terrestrial exoplanets from 1 to 2.5 R(sub E) is investigated using a propagator matrix method for a variety of layer structures. Particular attention is paid to ice-silicate hybrid super-Earths, where a significant ice mantle is modeled to rest atop an iron-silicate core, and may or may not contain a liquid water ocean. We find multilayer modeling often increases tidal dissipation relative to a homogeneous model, across multiple orbital periods, due to the ability to include smaller volume low viscosity regions, and the added flexure allowed by liquid layers. Gradations in parameters with depth are explored, such as allowed by the Preliminary Earth Reference Model. For ice-silicate hybrid worlds, dramatically greater dissipation is possible beyond the case of a silicate mantle only, allowing non-negligible tidal activity to extend to greater orbital periods than previously predicted. Surface patterns of tidal heating are found to potentially be useful for distinguishing internal structure. The influence of ice mantle depth and water ocean size and position are shown for a range of forcing frequencies. Rates of orbital circularization are found to be 10-100 times faster than standard predictions for Earth-analog planets when interiors are moderately warmer than the modern Earth, as well as for a diverse range of ice-silicate hybrid super-Earths. Circularization rates are shown to be significantly longer for planets with layers equivalent to an ocean-free modern Earth, as well as for planets with high fractions of either ice or silicate melting.

  4. Tidal heating in multilayered terrestrial exoplanets

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Wade G.; Hurford, Terry, E-mail: [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)


    The internal pattern and overall magnitude of tidal heating for spin-synchronous terrestrial exoplanets from 1 to 2.5 R{sub E} is investigated using a propagator matrix method for a variety of layer structures. Particular attention is paid to ice-silicate hybrid super-Earths, where a significant ice mantle is modeled to rest atop an iron-silicate core, and may or may not contain a liquid water ocean. We find multilayer modeling often increases tidal dissipation relative to a homogeneous model, across multiple orbital periods, due to the ability to include smaller volume low viscosity regions, and the added flexure allowed by liquid layers. Gradations in parameters with depth are explored, such as allowed by the Preliminary Earth Reference Model. For ice-silicate hybrid worlds, dramatically greater dissipation is possible beyond the case of a silicate mantle only, allowing non-negligible tidal activity to extend to greater orbital periods than previously predicted. Surface patterns of tidal heating are found to potentially be useful for distinguishing internal structure. The influence of ice mantle depth and water ocean size and position are shown for a range of forcing frequencies. Rates of orbital circularization are found to be 10-100 times faster than standard predictions for Earth-analog planets when interiors are moderately warmer than the modern Earth, as well as for a diverse range of ice-silicate hybrid super-Earths. Circularization rates are shown to be significantly longer for planets with layers equivalent to an ocean-free modern Earth, as well as for planets with high fractions of either ice or silicate melting.

  5. Tidal variations in the Sundarbans Estuarine System, India

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 122; Issue 4. Tidal variations in the Sundarbans Estuarine System, India. Meenakshi Chatterjee D Shankar G K Sen P Sanyal D Sundar G S Michael Abhisek Chatterjee P Amol Debabrata Mukherjee K Suprit A Mukherjee V Vijith Siddhartha Chatterjee Anwesha ...

  6. Effects of manual percussion during postural drainage on lung volumes and metabolic status in healthy subjects. (United States)

    Leelarungrayub, Jirakrit; Eungpinichpong, Wichai; Klaphajone, Jakkrit; Prasannarong, Mujalin; Boontha, Kritsana


    The aim of this study was to evaluate the influence of manual percussion during three different positions of postural drainage (PD) on lung volumes and metabolic status. Twenty six healthy volunteers (13 women and 13 men), with a mean age of 20.15 ± 1.17 years, participated. They were randomized into three standard positions of PD (upper, middle, or lower lobes) and given manual percussion at a frequency of 240 times per minute for 5 min. Lung volumes, including tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume (ERV) and vital capacity (VC); and metabolic status, such as oxygen consumption (VO2), carbon dioxide (VCO2), respiratory rate (RR), and minute ventilation (VE) were evaluated. The lung volumes showed no statistical difference in VC or IRV from percussion during PD in all positions, except for the lower lobe, where increased TV and decreased ERV were found when compared to PD alone. Furthermore, percussion during PD of the upper and middle lobes did not affect RR or VE, when compared to PD alone. In addition, percussion during PD of the middle and lower lobes increased VO2 and VCO2 significantly, when compared to PD alone, but it did not influence PD of the upper lobe. This study indicated that up to 5 min of manual percussion on PD of the upper and middle lobes is safe mostly for lung volumes, RR, and VE, but it should be given with care in PD conditions of the lower lobe. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Tidal energy site - Tidal energy site mammal/bird survey (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A vessel-based line visual transect survey was conducted for birds and marine mammals near the proposed Snohomish County PUD Admiralty Inlet tidal energy site...

  8. Tidal Power Plant Energy Estimation


    Silva–Casarín R.; Hiriart–Le Bert G.; López–González J.


    In this paper a methodology is presented which allows a quick and simple means of estimating the potential energy that can be obtained from a tidal power plant. The evaluation is made using a normalised nomograph, which is a function of the area of the tidal basin against the electricity installed capacity to thus obtain the potential energy for any location. The results describe two means of operation, one of "flow tide" and the other "flow–ebb tides", with two tidal basin systems operating:...

  9. Tidal controls on riverbed denitrification along a tidal freshwater zone (United States)

    Knights, Deon; Sawyer, Audrey H.; Barnes, Rebecca T.; Musial, Cole T.; Bray, Samuel


    In coastal rivers, tidal pumping enhances the exchange of oxygen-rich river water across the sediment-water interface, controlling nitrogen cycling in riverbed sediment. We developed a one-dimensional, fluid flow and solute transport model that quantifies the influence of tidal pumping on nitrate removal and applied it to the tidal freshwater zone (TFZ) of White Clay Creek (Delaware, USA). In field observations and models, both oxygenated river water and anoxic groundwater deliver nitrate to carbon-rich riverbed sediment. A zone of nitrate removal forms beneath the aerobic interval, which expands and contracts over daily timescales due to tidal pumping. At high tide when oxygen-rich river water infiltrates into the bed, denitrification rates decrease by 25% relative to low tide. In the absence of tidal pumping, our model predicts that the aerobic zone would be thinner, and denitrification rates would increase by 10%. As tidal amplitude increases toward the coast, nitrate removal rates should decrease due to enhanced oxygen exchange across the sediment-water interface, based on sensitivity analysis. Denitrification hot spots in TFZs are more likely to occur in less permeable sediment under lower tidal ranges and higher rates of ambient groundwater discharge. Our models suggest that tidal pumping is not efficient at removing surface water nitrate but can remove up to 81% of nitrate from discharging groundwater in the TFZ of White Clay Creek. Given the high population densities of coastal watersheds, the reactive riverbeds of TFZs play a critical role in mitigating new nitrogen loads to coasts.

  10. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.


    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels...... and on tidal flats due to the mixing caused by currents and waves. We apply bed level data to evaluate the amount of vertical sediment reworking in modern tidal channels and at a tidal flat. Cycles of deposition and erosion are measured with a bed level sensor, and the results show that gross sedimentation...... was several times higher than net sedimentation. We propose that tidal channel sediment is bleached either on the tidal flat before it is transported to the tidal channels and incorporated in channel-fill successions or, alternatively, on the shallow intertidal part of the channel banks. Based...

  11. Tidal Creek Sentinel Habitat Database (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ecological Research, Assessment and Prediction's Tidal Creeks: Sentinel Habitat Database was developed to support the National Oceanic and Atmospheric...

  12. Tidal locking of habitable exoplanets (United States)

    Barnes, Rory


    Potentially habitable planets can orbit close enough to their host star that the differential gravity across their diameters can produce an elongated shape. Frictional forces inside the planet prevent the bulges from aligning perfectly with the host star and result in torques that alter the planet's rotational angular momentum. Eventually the tidal torques fix the rotation rate at a specific frequency, a process called tidal locking. Tidally locked planets on circular orbits will rotate synchronously, but those on eccentric orbits will either librate or rotate super-synchronously. Although these features of tidal theory are well known, a systematic survey of the rotational evolution of potentially habitable exoplanets using classic equilibrium tide theories has not been undertaken. I calculate how habitable planets evolve under two commonly used models and find, for example, that one model predicts that the Earth's rotation rate would have synchronized after 4.5 Gyr if its initial rotation period was 3 days, it had no satellites, and it always maintained the modern Earth's tidal properties. Lower mass stellar hosts will induce stronger tidal effects on potentially habitable planets, and tidal locking is possible for most planets in the habitable zones of GKM dwarf stars. For fast-rotating planets, both models predict eccentricity growth and that circularization can only occur once the rotational frequency is similar to the orbital frequency. The orbits of potentially habitable planets of very late M dwarfs ([InlineEquation not available: see fulltext.]) are very likely to be circularized within 1 Gyr, and hence, those planets will be synchronous rotators. Proxima b is almost assuredly tidally locked, but its orbit may not have circularized yet, so the planet could be rotating super-synchronously today. The evolution of the isolated and potentially habitable Kepler planet candidates is computed and about half could be tidally locked. Finally, projected TESS planets

  13. Tidal locking of habitable exoplanets (United States)

    Barnes, Rory


    Potentially habitable planets can orbit close enough to their host star that the differential gravity across their diameters can produce an elongated shape. Frictional forces inside the planet prevent the bulges from aligning perfectly with the host star and result in torques that alter the planet's rotational angular momentum. Eventually the tidal torques fix the rotation rate at a specific frequency, a process called tidal locking. Tidally locked planets on circular orbits will rotate synchronously, but those on eccentric orbits will either librate or rotate super-synchronously. Although these features of tidal theory are well known, a systematic survey of the rotational evolution of potentially habitable exoplanets using classic equilibrium tide theories has not been undertaken. I calculate how habitable planets evolve under two commonly used models and find, for example, that one model predicts that the Earth's rotation rate would have synchronized after 4.5 Gyr if its initial rotation period was 3 days, it had no satellites, and it always maintained the modern Earth's tidal properties. Lower mass stellar hosts will induce stronger tidal effects on potentially habitable planets, and tidal locking is possible for most planets in the habitable zones of GKM dwarf stars. For fast-rotating planets, both models predict eccentricity growth and that circularization can only occur once the rotational frequency is similar to the orbital frequency. The orbits of potentially habitable planets of very late M dwarfs ([InlineEquation not available: see fulltext.]) are very likely to be circularized within 1 Gyr, and hence, those planets will be synchronous rotators. Proxima b is almost assuredly tidally locked, but its orbit may not have circularized yet, so the planet could be rotating super-synchronously today. The evolution of the isolated and potentially habitable Kepler planet candidates is computed and about half could be tidally locked. Finally, projected TESS planets

  14. High-resolution modeling assessment of tidal stream resource in Western Passage of Maine, USA (United States)

    Yang, Zhaoqing; Wang, Taiping; Feng, Xi; Xue, Huijie; Kilcher, Levi


    Although significant efforts have been taken to assess the maximum potential of tidal stream energy at system-wide scale, accurate assessment of tidal stream energy resource at project design scale requires detailed hydrodynamic simulations using high-resolution three-dimensional (3-D) numerical models. Extended model validation against high quality measured data is essential to minimize the uncertainties of the resource assessment. Western Passage in the State of Maine in U.S. has been identified as one of the top ranking sites for tidal stream energy development in U.S. coastal waters, based on a number of criteria including tidal power density, market value and transmission distance. This study presents an on-going modeling effort for simulating the tidal hydrodynamics in Western Passage using the 3-D unstructured-grid Finite Volume Community Ocean Model (FVCOM). The model domain covers a large region including the entire the Bay of Fundy with grid resolution varies from 20 m in the Western Passage to approximately 1000 m along the open boundary near the mouth of Bay of Fundy. Preliminary model validation was conducted using existing NOAA measurements within the model domain. Spatial distributions of tidal power density were calculated and extractable tidal energy was estimated using a tidal turbine module embedded in FVCOM under different tidal farm scenarios. Additional field measurements to characterize resource and support model validation were discussed. This study provides an example of high resolution resource assessment based on the guidance recommended by the International Electrotechnical Commission Technical Specification.

  15. The distribution and tapping tidal energy


    Zygmunt Kowalik


    Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the...

  16. Impact of intertidal area characteristics on estuarine tidal hydrodynamics: A modelling study for the Scheldt Estuary (United States)

    Stark, J.; Smolders, S.; Meire, P.; Temmerman, S.


    Marsh restoration projects are nowadays being implemented as ecosystem-based strategies to reduce flood risks and to restore intertidal habitat along estuaries. Changes in estuarine tidal hydrodynamics are expected along with such intertidal area changes. A validated hydrodynamic model of the Scheldt Estuary is used to gain fundamental insights in the role of intertidal area characteristics on tidal hydrodynamics and tidal asymmetry in particular through several geomorphological scenarios in which intertidal area elevation and location along the estuary is varied. Model results indicate that the location of intertidal areas and their storage volume relative to the local tidal prism determine the intensity and reach along the estuary over which tidal hydrodynamics are affected. Our model results also suggest that intertidal storage areas that are located within the main estuarine channel system, and hence are part of the flow-carrying part of the estuary, may affect tidal hydrodynamics differently than intertidal areas that are side-basins of the main estuarine channel, and hence only contribute little to the flow-carrying cross-section of the estuary. If tidal flats contribute to the channel cross-section and exert frictional effects on the tidal propagation, the elevation of intertidal flats influences the magnitude and direction of tidal asymmetry along estuarine channels. Ebb-dominance is most strongly enhanced if tidal flats are around mean sea level or slightly above. Conversely, flood-dominance is enhanced if the tidal flats are situated low in the tidal frame. For intertidal storage areas at specific locations besides the main channel, flood-dominance in the estuary channel peaks in the vicinity of those areas and generally reduces upstream and downstream compared to a reference scenario. Finally, the model results indicate an along-estuary varying impact on the tidal prism as a result of adding intertidal storage at a specific location. In addition to known

  17. Tidal Power Plant Energy Estimation

    Directory of Open Access Journals (Sweden)

    Silva–Casarín R.


    Full Text Available In this paper a methodology is presented which allows a quick and simple means of estimating the potential energy that can be obtained from a tidal power plant. The evaluation is made using a normalised nomograph, which is a function of the area of the tidal basin against the electricity installed capacity to thus obtain the potential energy for any location. The results describe two means of operation, one of "flow tide" and the other "flow–ebb tides", with two tidal basin systems operating: single and double reservoir systems. To obtain the normalised nomograph the numerical results for simulations of several tidal power plants under differing operational conditions over a period of one year. These conditions were established by varying the electricity installed capacity, the hydraulic conditions in "flow tide", "ebb tides" or both and with single or double reservoir systems and using sea level information taken every 15 minutes. To validate the model information from the tidal power plant at Rance, France, was used, which includes data concerning production, electricity installed capacity, turbine characteristics and tidal ranges. A very good correlation was found between the results of the numerical model and those reported in various technical reports.

  18. Avaliação do pico de pressão, do volume corrente e da freqüência respiratória durante ventilação de carneiros prematuros utilizando balão auto-inflável Evaluation of peak inspiratory pressure, tidal volume and respiratory rate during ventilation of premature lambs using a self-inflating bag

    Directory of Open Access Journals (Sweden)

    Jefferson G. Resende


    Full Text Available OBJETIVO: Avaliar o pico de pressão inspiratória, o volume corrente e a freqüência respiratória obtidos durante ventilação manual de carneiros prematuros, utilizando balão auto-inflável. MÉTODOS: Estudo experimental descritivo em que cinco duplas de médicos selecionados aleatoriamente entre 35 neonatologistas que trabalham em unidade de terapia intensiva neonatal e experientes em reanimação de recém-nascidos ventilaram cinco carneiros prematuros intubados, utilizando balão auto-inflável. Os sinais de pressão e fluxo eram captados, convertidos por meio de transdutores e digitalizados para armazenamento e análise. Foram avaliadas curvas de pressão e de volume corrente, este a partir da integral do fluxo, em suas medidas de pico, nos 50 segundos finais de cada 5 minutos. RESULTADOS: A mediana da pressão foi de 39,8 (IQ25-75% 30,2-47,2 cmH2O; foi menor que 20 em 1,1% das vezes e maior que 40 em 49,1%. Sete em 10 médicos propiciaram mais de seis picos de pressão maiores que 40 cmH2O. A mediana do volume corrente/kg foi de 17,8 (IQ25-75% 14,1-22,4 mL, sendo menor que 5 mL em 0,1% das vezes e igual ou maior que 20 mL em 37,7%. Todos os médicos impuseram cinco ou mais ciclos ventilatórios com volume corrente/kg de 20 mL ou mais. A freqüência situou-se entre 30 e 60 ciclos/minuto em 65,9% das vezes, sendo menor que 30 em 6,8% e maior que 60 em 27,3% das vezes. CONCLUSÃO: Ocorreu grande variabilidade nos valores do pico de pressão inspiratória e do volume corrente/kg, sendo muitas vezes elevados e alcançando níveis indutores de biotrauma; para a freqüência respiratória, os valores foram adequados na maioria das vezes.OBJECTIVE: To evaluate the peak inspiratory pressure, tidal volume and respiratory rate achieved during manual ventilation of premature lambs, using a self-inflating bag. METHODS: In this descriptive, experimental study, five pairs of physicians, selected at random among 35 neonatologists working at a

  19. Alterações da pressão de pico inspiratório e do volume corrente fornecidos por reanimadores manuais com balão auto-inflável em função do fluxo de entrada de oxigênio utilizado Alterations in peak inspiratory pressure and tidal volume delivered by manually operated self-inflating resuscitation bags as a function of the oxygen supply rate

    Directory of Open Access Journals (Sweden)

    Armando Carlos Franco de Godoy


    Full Text Available OBJETIVO: Determinar possíveis alterações do volume corrente e da pressão de pico inspiratório fornecidos por sete modelos de reanimador manual com balão auto-inflável em função do fluxo de entrada de oxigênio utilizado. MÉTODOS: Os reanimadores testados foram: Oxigel, modelos A e B; CE Reanimadores; ProtecSolutions; Missouri; Axmed; e Narcosul. Para as aferições, acoplaram-se um fluxômetro de oxigênio de parede, um fluxômetro/respirômetro, um reanimador, um sensor (aparelho Tracer 5 e um pulmão-teste. Além disso, acoplou-se o aparelho Tracer 5 a um notebook. Utilizaram-se fluxos de entrada de oxigênio de 1, 5, 10 e 15 L/min. RESULTADOS: O volume corrente fornecido pelo reanimador Oxigel modelo A ao receber 15 L/min de oxigênio foi aproximadamente 99% maior que o fornecido ao receber 1 L/min de oxigênio. Da mesma forma, a pressão de pico inspiratório foi 155% maior. Nas mesmas condições, o volume corrente fornecido pelo reanimador Narcosul foi 48% maior, e a pressão de pico inspiratório foi 105% maior. Os demais reanimadores testados não apresentaram alterações significativas do volume corrente e da pressão de pico inspiratório fornecidos. CONCLUSÕES: Nas condições de resistência e complacência utilizadas, os reanimadores em que o fluxo de entrada de oxigênio é direcionado diretamente ao interior do balão tiveram a válvula do paciente presa em posição de inspiração ao receberem um fluxo > 5 L/min, aumentando significativamente o volume corrente e a pressão de pico inspiratório fornecidos. Isso não ocorreu nos reanimadores em que o fluxo de entrada de oxigênio é direcionado ao exterior do balão.OBJECTIVE: To assess possible alterations in the tidal volume and peak inspiratory pressure delivered by seven models of manually operated self-inflating resuscitation bags as a function of the oxygen supply rate used. METHODS: The resuscitation bags tested were the following: Oxigel, models A and B; CE

  20. Tidal effects on stellar activity (United States)

    Poppenhaeger, K.


    The architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and the exoplanet for such systems that are similar to the tidal interactions observed in close stellar binary systems. For the exoplanet, tidal interaction can lead to circularization of its orbit and the synchronization of its rotational and orbital period. For the host star, it has long been speculated if significant angular momentum transfer can take place between the planetary orbit and the stellar rotation. In the case of the Earth-Moon system, such tidal interaction has led to an increasing distance between Earth and Moon. For stars with Hot Jupiters, where the orbital period of the exoplanet is typically shorter than the stellar rotation period, one expects a decreasing semimajor axis for the planet and enhanced stellar rotation, leading to increased stellar activity. Also excess turbulence in the stellar convective zone due to rising and subsiding tidal bulges may change the magnetic activity we observe for the host star. I will review recent observational results on stellar activity and tidal interaction in the presence of close-in exoplanets, and discuss the effects of enhanced stellar activity on the exoplanets in such systems.

  1. Tidal variations of earth rotation (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.


    The periodic variations of the earths' rotation resulting from the tidal deformation of the earth by the sun and moon were rederived including terms with amplitudes of 0.002 millisec and greater. The series applies to the mantle, crust, and oceans which rotate together for characteristic tidal periods; the scaling parameter is the ratio of the fraction of the Love number producing tidal variations in the moment of inertia of the coupled mantle and oceans (k) to the dimensionless polar moment of inertia of the coupled moments (C). The lunar laser ranging data shows that k/C at monthly and fortnightly frequencies equals 0.99 + or - 0.15 and 0.99 + or - 0.20 as compared to the theoretical value of 0.94 + or - 0.04.

  2. Korea tidal power and beyond (United States)

    Song, W. O.; van Walsum, E.

    A study evaluating the tidal power potential on the west coast of Korea is presented. The tidal power plant concept applied to all sites features prefabricated caissons from which the powerhouse and the sluice sections of the plant are built up. In the screening process, all 13 potential sites were compared on the basis of a single basin and single effect schemes operated to produce the maximum amount of energy. The four sites identified as having potential for development (the inner Asan Bay, the outer Asan Bay, the Incheon Bay, and the Garorim Bay) are economically evaluated. It is noted that harbor development and land reclamation can proceed in conjunction with tidal power development.

  3. Properties of active tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Lefebvre, Alice; Becker, Marius


    Bedforms of various shapes and sizes are ubiquitous in tidal channels, inlets and estuaries. They constitute a form roughness which has a large scale effect on the hydrodynamics and sediment transport of coastal environments. It has been shown that this form roughness can be expressed in terms...... of the lee side slope of bedforms. This study compiles data on the topography and hydraulics of compound dunes from different settings in the German Bight to discuss implications of a critical lee slope in tidal environments with reversing flow. Data from the Weser estuary is used to exemplify and quantify...

  4. The Kislaya Guba tidal power plant

    National Research Council Canada - National Science Library

    Bernshtein, L.B; Gavrilov, V.G; Gel'fer, S.L; Nehoroshev, N.N; Suponitskii, L.I; Usachev, I.N; Monosov, M.L; Silakov, V.N; Pylev, I.M; Platov, V.I; Vestfal, V.L; Trifel, M.S


    This book examines the experience of designing, constructing, and testing the experimental Kislaya Guba tidal power plant, which was created in order to examine new methods of utilizing tidal energy...

  5. The distribution and tapping tidal energy

    Directory of Open Access Journals (Sweden)

    Zygmunt Kowalik


    Full Text Available Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the construction of small, efficient and inexpensive underwater turbines admit the possibility of small scale operations that will use local tidal currents to bring electricity to remote locations. Since the generation of such electricity is concerned with the tidal energy in local water bodies, it is important to understand the site-specific energy balance, i.e., the energy flowing in through open boundaries, and the energy generated and dissipated within the local domain. The question is how to tap the tidal energy while keeping possible changes in the present tidal regimes to a minimum. The older approach of constructing barrages may still be quite useful in some locations. The basics of such tidal power plants constructed in a small bay are analyzed in order to understand the principal parameter for tidal plant evaluation, i.e., the power produced.     The new approach is to place turbines - devices similar to windmills - in the pathway of tidal currents. Theoretically, the amount of power available by such turbines for electricity generation is proportional to the water density and velocity cubed of the tidal flow. The naturally dissipated tidal power due to bottom friction forces is also proportional to the cube of the velocity. Because of this similarity, the exploitation of tidal energy can be directed to reinvesting the naturally dissipated power into tidal power for the generation of electricity. This approach to tidal power exploitation is better tuned

  6. Turning the tide : tidal power in the UK


    Sustainable Development Commission


    Contents: Turning the tide : tidal power in the UK -- Executive summary -- Tidal power in the UK : research report 1 : UK tidal resource assessment -- Tidal power in the UK : research report 2 : tidal technologies overview -- Tidal power in the UK : research report 3 : Severn barrage proposals -- Tidal power in the UK : research report 4 : Severn non-barrage options -- Tidal power in the UK : research report 5 : UK case studies. Summarised in the Welsh language version of the executive ...

  7. Sanat ve taklit

    Directory of Open Access Journals (Sweden)

    Muhammed NACAR


    Full Text Available Bu çalışma tarih boyunca sanat üzerine konuşmuş önemli düşünürlerin sanat kavramına yaklaşımlarını incelemektedir. Sanatın taklit(mimesis olduğuna dair ilk yaklaşım Plato'nun Devlet kitabında yer almıştır. Plato, sanatın aslında gerçeğin üçüncü kez taklit edildiğini iddia eder ve bunu örneklendirirken de sofa örneğini verir. Plato bir ressamın çizmiş olduğu bir sofanın idea'lar dünyasında bir imajı olduğunu marangozun bunu taklit ettiğini, sanatçının da marangozu taklit ettiğini dolayısıyla üçüncü kez orijinalinden uzaklaşmış bir imitasyon olduğunu söyler. Dolayısıyla da gerçek olmadığı için de yasaklanmasını savunur.

  8. Treinamento muscular melhora o volume corrente e a capacidade vital no pós-operatório de revascularização do miocárdio Inspiratory muscle training improves tidal volume and vital capacity after CABG surgery

    Directory of Open Access Journals (Sweden)

    Gabriela Bertolini Matheus


    Full Text Available OBJETIVO: Avaliar a função pulmonar e força da musculatura respiratória no período pós-operatório e verificar o efeito do treinamento muscular inspiratório sobre as medidas de desempenho da musculatura respiratória em pacientes submetidos à revascularização do miocárdio. MÉTODOS: Estudo randomizado, incluindo 47 pacientes submetidos à revascularização do miocárdio com circulação extracorpórea. Os pacientes foram divididos em grupo controle (GC, 24 pacientes, e grupo estudo (GE 23 pacientes, com idade média de 66,33 ± 10,20 anos e 61,83 ± 8,61 anos, respectivamente. O GE foi submetido à fisioterapia convencional e ao treinamento muscular inspiratório com threshold® IMT e o GC à fisioterapia convencional. Foram comparadas as pressões respiratórias máximas (Pimáx e Pemáx, volume corrente (VC, capacidade vital (CV e pico de fluxo expiratório (Peak Flow no pré-operatório (Pré-OP, 1º e 3º dias de pós-operatório (PO1 e (PO3. RESULTADOS: Observou-se redução significativa em todas as variáveis mensuradas no PO1, quando comparadas ao pré-operatório, nos dois grupos estudados, Pimáx (POBJECTIVE: To evaluate lung function and respiratory muscle strength in the postoperative period and investigate the effect of inspiratory muscle training on measures of respiratory muscle performance in patients undergoing coronary artery bypass grafting. METHODS: A randomized study with 47 patients undergoing coronary artery bypass grafting with cardiopulmonary bypass. They were divided into study group (SG 23 patients and control group (CG 24 patients, mean age 61.83 ± 8.61 and 66.33 ± 10.20 years, EuroSCORE SG 0.71 ± 0.0018 and CG 0.76 ± 0.0029, respectively. The study group underwent physical therapy and inspiratory muscle training with threshold IMT® and CG underwent conventional physiotherapy. We compared the maximal respiratory pressures (MIP and MEP, tidal volume (TV, vital capacity (VC and peak expiratory flow

  9. Mikrobiyota ve Nörodejenerasyon


    Alagöz, Aybala Neslihan


    İnsan bağırsağı; bakteriler, mantarlar, parazitler ve virüsler gibi çeşitli mikroorganizmaları içerir ve mikrobiyota; insanlarla birlikte yaşayan özel türlerin tamamını ifade eder. Pekçok iç ve dış etken sonucu gelişebilen sağlıksız mikrobiyota için, “disbiyozis” terimi kullanılmaktadır. Beyin ve bağırsak; enterik sinir sistemi (ESS), vagus siniri, immün sistem veya bağırsak mikroorganizma-larının metabolik süreçleri de dahil olmak üzere çeşitli yollarla bağlanabilir. Disbiyozis durumunda, bu...

  10. Tidal currents and Kuroshio transport variations in the Tokara Strait estimated from ferryboat ADCP data (United States)

    Zhu, Xiao-Hua; Nakamura, Hirohiko; Dong, Menghong; Nishina, Ayako; Yamashiro, Toru


    From 2003 to 2011, current surveys, using an acoustic Doppler current profiler (ADCP) mounted on the Ferry Naminoue, were conducted across the Tokara Strait (TkS). Resulting velocity sections (1234) were used to estimate major tidal current constituents in the TkS. The semidiurnal M2 tidal current (maximum amplitude 27 cm s-1) was dominant among all the tidal constituents, and the diurnal K1 tidal current (maximum amplitude 21 cm s-1) was the largest among all the diurnal tidal constituents. Over the section, the ratios, relative to M2, of averaged amplitudes of M2, S2, N2, K2, K1, O1, P1, and Q1 tidal currents were 1.00:0.44:0.21:0.12:0.56:0.33:0.14:0.10. Tidal currents estimated from the ship-mounted ADCP data were in good agreement with those from the mooring ADCP data. Their root-mean-square difference for the M2 tidal current amplitude was 2.0 cm s-1. After removing the tidal currents, the annual-mean of the net volume transport (NVT) through the TkS ± its standard derivation was 23.03 ± 3.31 Sv (Sv = 106 m3 s-1). The maximum (minimum) monthly mean NVT occurred in July (November) with 24.60 (21.47) Sv. NVT values from the ship-mounted ADCP were in good agreement with previous geostrophic volume transports calculated from conductivity temperature depth data, but the former showed much finer temporal structure than those from the geostrophic calculation.

  11. General relativistic tidal heating for Moller pseudotensor

    CERN Document Server

    So, Lau Loi


    Thorne elucidated that the relativistic tidal heating is the same as the Newtonian theory. Moreover, Thorne also claimed that the tidal heating is independent of how one localizes gravitational energy and is unambiguously given by a certain formula. Purdue and Favata calculated the tidal heating for different classical pseudotensors including Moller and obtained the results all matched with the Newtonian perspective. After re-examined this Moller pseudotensor, we find that there does not exist any tidal heating value. Thus we claim that the relativistic tidal heating is pseudotensor independent under the condition that if the peusdotensor is a Freud typed superpotential.

  12. Evaulation of perennial pepperweed (Lepidium latifolium) management in a seasonal wetland in San Francisco Estuary prior to restoration of tidal hydrology (United States)

    Herbicide applications have shown potential for control and management of invasive perennial pepperweed (Lepidium latifolium) in rangelands and tidal wetlands. However, reported efficacy of management methods varies widely, and the effects of more recently labeled aquatic herbicides on non-target ve...

  13. Maine Tidal Power Initiative: Environmental Impact Protocols For Tidal Power

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Michael Leroy [Univ. of Maine, Orono, ME; Zydlewski, Gayle Barbin [Univ. of Maine, Orono, ME; Xue, Huijie [Univ. of Maine, Orono, ME; Johnson, Teresa R. [Univ. of Maine, Orono, ME


    The Maine Tidal Power Initiative (MTPI), an interdisciplinary group of engineers, biologists, oceanographers, and social scientists, has been conducting research to evaluate tidal energy resources and better understand the potential effects and impacts of marine hydro-kinetic (MHK) development on the environment and local community. Project efforts include: 1) resource assessment, 2) development of initial device design parameters using scale model tests, 3) baseline environmental studies and monitoring, and 4) human and community responses. This work included in-situ measurement of the environmental and social response to the pre-commercial Turbine Generator Unit (TGU®) developed by Ocean Renewable Power Company (ORPC) as well as considering the path forward for smaller community scale projects.

  14. Limits to tidal current power

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, Chris [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Cummins, Patrick [Institute of Ocean Sciences, Fisheries and Oceans (Canada)


    Estimating the extractable power of tidal currents in channels is a practical question that has received attention recently. Analysis has clearly shown that the power potential is not given by the flux of kinetic energy, as has been commonly assumed. A general formula for the maximum available power is reviewed, along with assessments of the reduction if only partial fences are used, as would be required for navigational and ecological reasons. In typical situations, the maximum power obtainable may be achieved with a surprisingly small number of turbines, especially if allowance is made for the flow reduction caused by drag on the supporting structures of turbines which reduces the maximum power available. Finally, the flow through tidal turbines is compared with the cooling water demands of nuclear reactors generating the same power. (author)

  15. Trans World Tidal Gravity Profile. (United States)


    2 :Areas added or modified in the SchwidersKi maps. 7 Asin’m AC TB, 6 R A cos a Figure 3 A observed vector (A amplitude, = : phase) R tidal vector ...for an elastic non-viscous earth with liquid core but oceanless (R : amplitude, zero phase) L ocean attraction and loading vector (L : amplitude, X...3M D 80KM CENTRO POLITECNICO- GEODESIA -U.F*PR. PROF. CGEMAEL GRAVIMETRE GEODYNAMICS 783 PMELCHIOR - OBSERVATOIRE ROYAL DC BCLGIQUE CALIBRATION

  16. Tidal Dissipation in WASP-12 (United States)

    Weinberg, Nevin N.; Sun, Meng; Arras, Phil; Essick, Reed


    WASP-12 is a hot Jupiter system with an orbital period of P = 1.1 days, making it one of the shortest-period giant planets known. Recent transit timing observations by Maciejewski et al. and Patra et al. found a decreasing period with P/| \\dot{P}| = 3.2 Myr. This has been interpreted as evidence of either orbital decay due to tidal dissipation or a long-term oscillation of the apparent period due to apsidal precession. Here, we consider the possibility that it is orbital decay. We show that the parameters of the host star are consistent with either a M * ≃ 1.3 M ⊙ main sequence star or a M * ≃ 1.2 M ⊙ subgiant. We find that if the star is on the main sequence, the tidal dissipation is too inefficient to explain the observed \\dot{P}. However, if it is a subgiant, the tidal dissipation is significantly enhanced due to nonlinear wave-breaking of the dynamical tide near the star’s center. The subgiant models have a tidal quality factor Q{{\\prime} }* ≃ 2× {10}5 and an orbital decay rate that agrees well with the observed \\dot{P}. It would also explain why the planet survived for ≃3 Gyr while the star was on the main sequence and yet is now inspiraling on a 3 Myr timescale. Although this suggests that we are witnessing the last ∼0.1% of the planet’s life, the probability of such a detection is a few percent given the observed sample of ≃30 hot Jupiters in P 1.2 M ⊙ hosts.

  17. Modeling Interactions between Backbarrier Marshes, Tidal Inlets, Ebb-deltas, and Adjacent Barriers Exposed to Rising Sea Levels (United States)

    Hanegan, K.; Georgiou, I. Y.; FitzGerald, D.


    Along barrier island chains, tidal exchange between the backbarrier and the coastal ocean supports unique saltwater and brackish ecosystems and is responsible for exporting sediment and nutrients to the surrounding coast. Tidal prism, basement controls, and wave and tidal energy dictate the size and number of tidal inlets and the volume of sand sequestered in ebb-tidal deltas. The inlet tidal prism is a function of bay area, tidal range, and secondary controls, including flow inertia, basinal hypsometry, and frictional factors. Sea- level rise (SLR) is threatening coastal environments, causing mainland flooding, changes in sediment supply, and conversion of wetlands and tidal flats to open water. These factors are impacting basinal hypsometry and increasing open water area, resulting in enlarging tidal prisms, increased dimensions of tidal inlets and ebb-tidal deltas, and erosion along adjacent barrier shorelines. Although the effects of SLR on coastal morphology are difficult to study by field observations alone, physics-based numerical models provide a sophisticated means of analyzing coastal processes over decadal time-scales and linking process causation to long term development. Here, we use a numerical model that includes relevant features in the barrier/tidal basin system, linking back-barrier marsh degradation, inlet expansion, and ebb-delta growth to barrier erosion through long-term hydrodynamic and morphology simulations. Sediment exchange and process interactions are investigated using an idealized domain resembling backbarrier basins of mixed energy coasts so that the sensitivity to varying SLR rates, interior marsh loss, sediment supply, and hydrodynamic controls can be more easily analyzed. Model runs explore these processes over geologic time scales, demonstrating the vulnerability of backbarrier systems to projected SLR and marsh loss. Results demonstrate the links between changing basin morphology and shoreface sedimentation patterns that initiate


    Energy Technology Data Exchange (ETDEWEB)

    Efroimsky, Michael; Makarov, Valeri V., E-mail:, E-mail: [US Naval Observatory, Washington, DC 20392 (United States)


    Tidal torques play a key role in rotational dynamics of celestial bodies. They govern these bodies' tidal despinning and also participate in the subtle process of entrapment of these bodies into spin-orbit resonances. This makes tidal torques directly relevant to the studies of habitability of planets and their moons. Our work begins with an explanation of how friction and lagging should be built into the theory of bodily tides. Although much of this material can be found in various publications, a short but self-consistent summary on the topic has been lacking in the hitherto literature, and we are filling the gap. After these preparations, we address a popular concise formula for the tidal torque, which is often used in the literature, for planets or stars. We explain why the derivation of this expression, offered in the paper by Goldreich and in the books by Kaula (Equation (4.5.29)) and Murray and Dermott (Equation (4.159)), implicitly sets the time lag to be frequency independent. Accordingly, the ensuing expression for the torque can be applied only to bodies having a very special (and very hypothetical) rheology which makes the time lag frequency independent, i.e., the same for all Fourier modes in the spectrum of tide. This expression for the torque should not be used for bodies of other rheologies. Specifically, the expression cannot be combined with an extra assertion of the geometric lag being constant, because at finite eccentricities the said assumption is incompatible with the constant-time-lag condition.

  19. Observations of a tidal intrusion front in a tidal channel (United States)

    Lu, Shasha; Xia, Xiaoming; Thompson, Charlie E. L.; Cao, Zhenyi; Liu, Yifei


    A visible front indicated by a surface colour change, and sometimes associated with foam or debris lines, was observed in a tidal channel during neap tide. This is an example of a tidal intrusion front occurring in the absence of sudden topographical changes or reversing flows, typically reported to be associated with such fronts. Detailed Acoustic Doppler Current Profiler and conductivity/temperature/depth measurements were taken on repeated transects both with fronts apparent and with fronts absent. The results indicated that the front occurred as a result of stratification, which was sustained by the buoyancy flux and the weak tide-induced mixing during neap ebb tide. The stronger tide-induced mixing during spring tide restrained stratification, leading to the absence of a front. The mechanism of the frontogenesis was the density gradient between the stratified water formed during neap ebb tide, and the more mixed seawater during neap flood tide; thus, the water on the landward (southwestern) side of the front was stratified, and that on the seaward side (northeastern) of the front was vertically well mixed. Gradient Richardson number estimates suggest that the flow between the stratified and mixed water was near the threshold 0.25 for shear instability. Meanwhile, the density gradient would provide an initial baroclinic contribution to velocity convergence, which is indicated by the accumulation of buoyant matter such as foam, grass, and debris into a sharply defined line along the surface. The front migrates with the flood current, with a local maximum towards the eastern side of the channel, leading to an asymmetrical shape with the eastern side of the front driven further into the Tiaozhoumen tidal channel.

  20. Dynamics of tidal and non-tidal currents along the southwest continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Aruna, C.; Ravichandran, C.; Srinivas, K.; Rasheed, P.A.A; Lekshmi, S.

    The tidal regimes over the continental shelves are often less documented due to lack of coastal water level data. This is of concern since continental shelves rule the global dissipation of tidal energy. The tides along the Southwest Indian shelf...

  1. Avaliação da relação entre espaço morto e volume corrente como índice preditivo de falha de extubação Evaluation of the dead space to tidal volume ratio as a predictor of extubation failure

    Directory of Open Access Journals (Sweden)

    Albert Bousso


    Full Text Available OBJETIVO: O objetivo do estudo foi avaliar a relação entre espaço morto e volume corrente (VD/VT como preditivo de falha na extubação de crianças sob ventilação mecânica. MÉTODOS: Entre setembro de 2001 e janeiro de 2003, realizamos uma coorte, na qual foram incluídas todas as crianças (1 dia-15 anos submetidas a ventilação mecânica na unidade de terapia intensiva pediátrica em que foi possível realizar a extubação e a ventilometria pré-extubação com a medida do índice VD/VT. Considerou-se falha na extubação a necessidade de reinstituição de algum tipo de assistência ventilatória, invasiva ou não, em um período de 48 horas. Para a análise dos pacientes que foram reintubados, definiu-se como sucesso-R a não reintubação. Para as análises estatísticas, utilizou-se um corte do VD/VT de 0,65. RESULTADOS: No período estudado, 250 crianças receberam ventilação mecânica na unidade de terapia intensiva pediátrica. Destas, 86 compuseram a amostra estudada. Vinte e uma crianças (24,4% preencheram o critério de falha de extubação, com 11 (12,8% utilizando suporte não-invasivo e 10 (11,6% reintubadas. A idade média foi de 16,8 (±30,1 meses, e a mediana, de 5,5 meses. A média do índice VD/VT de todos os casos foi de 0,62 (±0,18. As médias do índice VD/VT para os pacientes que tiveram a extubação bem sucedida e para os que falharam foram, respectivamente, 0,62 (±0,17 e 0,65 (±0,21 (p = 0,472. Na regressão logística, o índice VD/VT não apresentou correlação estatisticamente significativa com o sucesso ou não da extubação (p = 0,8458, nem para aqueles que foram reintubados (p = 0,5576. CONCLUSÕES: Em uma população pediátrica submetida a ventilação mecânica, por etiologias variadas, o índice VD/VT não possibilitou predizer qual a população de risco para falha de extubação ou reintubação.OBJECTIVE: The objective of this study was to evaluate the ratio of dead space to tidal volume

  2. Array Optimization for Tidal Energy Extraction in a Tidal Channel – A Numerical Modeling Analysis


    Yang, Zhaoqing; Wang, Taiping; Copping, Andrea


    This paper presents an application of a hydrodynamic model to simulate tidal energy extraction in a tidal dominated estuary in the Pacific Northwest coast. A series of numerical experiments were carried out to simulate tidal energy extraction with different turbine array configurations, including location, spacing and array size. Preliminary model results suggest that array optimization for tidal energy extraction in a real-world site is a very complex process that requires consideration of m...

  3. Storm surge and tidal range energy (United States)

    Lewis, Matthew; Angeloudis, Athanasios; Robins, Peter; Evans, Paul; Neill, Simon


    The need to reduce carbon-based energy sources whilst increasing renewable energy forms has led to concerns of intermittency within a national electricity supply strategy. The regular rise and fall of the tide makes prediction almost entirely deterministic compared to other stochastic renewable energy forms; therefore, tidal range energy is often stated as a predictable and firm renewable energy source. Storm surge is the term used for the non-astronomical forcing of tidal elevation, and is synonymous with coastal flooding because positive storm surges can elevate water-levels above the height of coastal flood defences. We hypothesis storm surges will affect the reliability of the tidal range energy resource; with negative surge events reducing the tidal range, and conversely, positive surge events increasing the available resource. Moreover, tide-surge interaction, which results in positive storm surges more likely to occur on a flooding tide, will reduce the annual tidal range energy resource estimate. Water-level data (2000-2012) at nine UK tide gauges, where the mean tidal amplitude is above 2.5m and thus suitable for tidal-range energy development (e.g. Bristol Channel), were used to predict tidal range power with a 0D modelling approach. Storm surge affected the annual resource estimate by between -5% to +3%, due to inter-annual variability. Instantaneous power output were significantly affected (Normalised Root Mean Squared Error: 3%-8%, Scatter Index: 15%-41%) with spatial variability and variability due to operational strategy. We therefore find a storm surge affects the theoretical reliability of tidal range power, such that a prediction system may be required for any future electricity generation scenario that includes large amounts of tidal-range energy; however, annual resource estimation from astronomical tides alone appears sufficient for resource estimation. Future work should investigate water-level uncertainties on the reliability and

  4. Eddy Generation and Shedding in a Tidally Energetic Channel (United States)

    McIlvenny, J.; Gillibrand, P. A.; Walters, R. A.


    The Pentland Firth in northern Scotland, and its subsidiary channel the Inner Sound, are currently under scrutiny as the first tidal energy array in the world is installed during 2016. The tidal flows in the channel and sound have been intensively observed and modelled in recent years, and the turbulent nature of the flow, with features of eddy generation and shedding, is becoming increasingly well known. Turbulence and eddies pose potential risks to the turbine infrastructure through enhanced stress on the blades, while understanding environmental effects of energy extraction also requires accurate simulation of the hydrodynamics of the flow. Here, we apply a mixed finite element/finite volume hydrodynamic model to the northern Scottish shelf, with a particular focus on flows through the Pentland Firth and the Inner Sound. We use an unstructured grid model, which allows the open boundaries to be far removed from the region of interest, while still allowing a grid spacing of 40m in the Inner Sound. The model employs semi-implicit techniques to solve the momentum and free surface equations, and semi-Lagrangian methods to solve the material derivative in the momentum equation, making it fast, robust and accurate and suitable for simulating flows in irregular coastal ocean environments. The model is well suited to address questions relating to tidal energy potential. We present numerical simulations of tidal currents in The Pentland Firth and Inner Sound. Observed velocities in the Inner Sound, measured by moored ADCP deployments, reach speeds of up to 5 m s-1 and the model successfully reproduces these strong currents. In the simulations, eddies are formed by interactions between the strong flow and the northern and southern headlands on the island of Stroma; some of these eddies are trapped and remain locked in position, whereas others are shed and transported away from the generation zone. We track the development and advection of eddies in relation to the site of

  5. Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh (United States)

    Vandenbruwaene, W.; Maris, T.; Cahoon, D.R.; Meire, P.; Temmerman, S.


    Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land with a ca. 3 m lower elevation than the natural tidal marshes. In this study we compared the long-term change in elevation (ΔE) within a CRT marsh and adjacent natural tidal marsh. Over a period of 4 years, the observed spatio-temporal variations in ΔE rate were related to variations in inundation depth, and this relationship was not significantly different for the CRT marsh and natural tidal marsh. A model was developed to simulate the ΔE over the next century. (1) Under a scenario without mean high water level (MHWL) rise in the estuary, the model shows that the marsh elevation-ΔE feedback that is typical for a natural tidal marsh (i.e. rising marsh elevation results in decreasing inundation depth and therefore a decreasing increase in elevation) is absent in the basin of the CRT marsh. This is because tidal exchange of water volumes between the estuary and CRT marsh are independent from the CRT marsh elevation but dependent on the culvert dimensions. Thus the volume of water entering the CRT remains constant regardless of the marsh elevation. Consequently the CRT MHWL follows the increase in CRT surface elevation, resulting after 75 years in a 2–2.5 times larger elevation gain in the CRT marsh, and a faster reduction of spatial elevation differences. (2) Under a scenario of constant MHWL rise (historical rate of 1.5 cm a-1), the equilibrium elevation (relative to MHWL) is 0.13 m lower in the CRT marsh and is reached almost 2 times faster. (3) Under a scenario of

  6. Microbial quality of a marine tidal pool

    CSIR Research Space (South Africa)

    Genthe, Bettina


    Full Text Available tidal pool water was compared to South African and other marine water quality guidelines. The microbial quality of a marine tidal pool on South Africa's Atlantic coast was found to be inferior to that of the adjoining seawater (the latter Complying...

  7. Organic matter processing in tidal estuaries

    NARCIS (Netherlands)

    Middelburg, J.J.; Herman, P.M.J.


    Processing of organic matter in tidal estuaries modifies its transfer from the river to the sea. We examined the distribution and the elemental and isotopic composition of organic matter in nine tidal estuaries along the Atlantic coast of Europe (Elbe, Ems, Thames, Rhine, Scheldt, Loire, Gironde,

  8. Tidal power from the Bay of Fundy

    Energy Technology Data Exchange (ETDEWEB)

    van Walsum, W.


    The potential for tidal power development in New Brunswick`s Bay of Fundy was discussed. Alternative methods of tidal plant operation, suitable for the site conditions of the head of the Bay (where there are two continuous basins), were described. Tidal power is strongly influenced by site conditions. A simple mathematical model has shown that for the location at the head of the Bay, a linked-basins plant could produce 5 per cent more energy with only 53 per cent of the power generating machinery that would be required for a conventional paired basins scheme. The challenge is to find an economical, environmentally friendly way of extracting power and energy from the tides. An early study series from 1966 to 1988 has shown that tidal power can be economical, yet nothing has materialized beyond an 18 MW pilot plant at Annapolis because of environmental concerns. In 1977, this single basin tidal power plant was found to increase the tidal range at Boston by 30 cm. It was suggested that a `tidal fence` may be an ecologically acceptable solution to this problem. Attention was drawn to the need to draft a master plan for the development of Fundy`s tidal power potential, making sure that early development does not jeopardize optimum development of the total resource. 8 refs., 6 figs.

  9. Tidal power plant prototype achieves 99% availability

    Energy Technology Data Exchange (ETDEWEB)

    DeLory, R.P.


    In 1984 the Annapolis Royal tidal power plant (Canada) was connected to the national grid and achieved 99% availability in its first year. It is the first tidal power plant built in North America and the first in the world which operates a large-diameter Straflo turbine.

  10. Prototype tidal power plant achieves 99% availability

    Energy Technology Data Exchange (ETDEWEB)

    De Lory, R.P.


    The Annapolis Royal (Canada) tidal power plant officially came on line in 1984. In its first year it achieved 99% availability. It is the first tidal power plant in North America and the first plant in the world to employ a large diameter Straflo turbine. The performance of the prototype plant is discussed.

  11. The CEVALE2VE case

    CERN Document Server

    Sanchez Pineda, Arturo; The ATLAS collaboration


    A virtual research and learning community can be a powerful tool for educational purposes. It has a wide range of possibilities for multi-institution participation, such as synchronous and asynchronous online engagement, decentralized student discussions and academic networking - as well as being cost effective. In this context, the CEVALE2VE virtual community (Centro de Altos Estudios de Altas Energías) is a Venezuelan initiative to support the new generation of researchers in high energy physics (HEP). Its goal is to contribute to the scientific dissemination of fundamental physics and the regional modernization of university education. The members of CEVALE2VE are a group of Venezuelan researchers, currently involved in projects related to the HEP field, and geographically located in different academic institutions of Europe and North America. The project involves several academic institutions in Venezuela and Colombia in order to reach a wide audience, and exploits current communications technologies, wh...

  12. The CEVALE2VE case

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00237353; The ATLAS collaboration


    A virtual research and learning community can be a powerful tool for educational purposes. It has a wide range of possibilities for multi-institution participation, such as synchronous and asynchronous online engagement, decentralized student discussions and academic networking - as well as being cost effective. In this context, the CEVALE2VE virtual community (Centro de Altos Estudios de Altas Energías) is a Venezuelan initiative to support the new generation of researchers in High Energy Physics (HEP). Its goal is to contribute to the scientific dissemination of fundamental physics and the regional modernization of university education. The members of CEVALE2VE are a group of Venezuelan researchers, currently involved in projects related to the HEP field, and geographically located in different academic institutions of Europe and North America. The project involves several academic institutions in Venezuela and Colombia in order to reach a wide audience, and exploits current communications technologies, w...

  13. Gustav Klimt Ve "Beethoven Friz"


    Fırıncı, Mehmet; Zencirci, Dizan Ercivan


    Bu makalede, tarihin hemen hemen her döneminde, paralel gelişim gösteren sanatın üç kolu olan resim, müzik ve mimariyi bir araya getiren "Gustav Klimt" ve sanatçının "Ayrılma (Secession)" döneminde meydana getirdiği başyapıt Beethoven Friz incelenecektir.Avusturyalı sanatçı Klimt, Secession binasının mimari durumunu değerlendirip, Beethoven' in 9.Senfonisi'nden ilham alarak yaptığı Beethoven Friz'i resmetmiştir. Döneminde sanat çevresince pek de anlaşılamamı...

  14. Tidal current and tidal energy changes imposed by a dynamic tidal power system in the Taiwan Strait, China (United States)

    Dai, Peng; Zhang, Jisheng; Zheng, Jinhai


    The Taiwan Strait has recently been proposed as a promising site for dynamic tidal power systems because of its shallow depth and strong tides. Dynamic tidal power is a new concept for extracting tidal potential energy in which a coast-perpendicular dike is used to create water head and generate electricity via turbines inserted in the dike. Before starting such a project, the potential power output and hydrodynamic impacts of the dike must be assessed. In this study, a two-dimensional numerical model based on the Delft3D-FLOW module is established to simulate tides in China. A dike module is developed to account for turbine processes and estimate power output by integrating a special algorithm into the model. The domain decomposition technique is used to divide the computational zone into two subdomains with grid refinement near the dike. The hydrodynamic processes predicted by the model, both with and without the proposed construction, are examined in detail, including tidal currents and tidal energy flux. The predicted time-averaged power yields with various opening ratios are presented. The results show that time-averaged power yield peaks at an 8% opening ratio. For semidiurnal tides, the flow velocity increases in front of the head of the dike and decreases on either side. For diurnal tides, these changes are complicated by the oblique incidence of tidal currents with respect to the dike as well as by bathymetric features. The dike itself blocks the propagation of tidal energy flux.

  15. Tidal ventilation distribution during pressure-controlled ventilation and pressure support ventilation in post-cardiac surgery patients. (United States)

    Blankman, P; VAN DER Kreeft, S M; Gommers, D


    Inhomogeneous ventilation is an important contributor to ventilator-induced lung injury. Therefore, this study examines homogeneity of lung ventilation by means of electrical impedance tomography (EIT) measurements during pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) using the same ventilation pressures. Twenty mechanically ventilated patients were studied after cardiac surgery. On arrival at the intensive care unit, ventilation distribution was measured with EIT just above the diaphragm for 15 min. After awakening, PCV was switched to PSV and EIT measurements were again recorded. Tidal impedance variation, a measure of tidal volume, increased during PSV compared with PCV, despite using the same ventilation pressures (P = 0.045). The distribution of tidal ventilation to the dependent lung region was more pronounced during PSV compared with PCV, especially during the first half of the inspiration. An even distribution of tidal ventilation between the dependent and non-dependent lung regions was seen during PCV at lower tidal volumes (ventilation was predominantly distributed to the dependent lung during PSV at low tidal volumes. In post-cardiac surgery patients, PSV showed improved ventilation of the dependent lung region due to the contribution of the diaphragm activity, which is even more pronounced during lower assist levels. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  16. No Snowball on Habitable Tidally Locked Planets (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.


    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin-orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  17. An equilibrium profile model for tidal environments

    Directory of Open Access Journals (Sweden)

    A. M. Bernabeu


    Full Text Available During a full tidal cycle, the beach profile is exposed to continuously changing hydrodynamical conditions. Consequently, the profile evolves constantly to adapt to these changes. The equilibrium condition on tidal beaches is defined in terms of the relative occurrence of swash, surf zone and shoaling processes. We have assumed that the tidal beach profile is in equilibrium when the net sediment transport along a tidal cycle is zero. In this model the contribution of swash is considered negligible. A simple and easy-to-apply equilibrium profile formulation is proposed. This model is based on the assumption that surf zone processes dominate the profile morphology wherever wave breaking occurs during the tidal cycle. The obtained equilibrium profile is valid from the high tide level to the breaker point at low tide level. The tidal influence on the profile morphology is the lengthening of the surf profile. The higher the tidal range, the longer the surf profile. The model was tested against field and laboratory data, showing reasonable predictions of measured beach profiles.

  18. Numerical study of the effects of mangrove areas and tidal flats on tides: A case study of Darwin Harbour, Australia (United States)

    Li, Li; Wang, Xiao Hua; Williams, David; Sidhu, Harvinder; Song, Dehai


    The tidal dynamics of Darwin Harbour, Australia, are simulated using a finite volume coastal ocean model. The calibrated model agreed well with the observed sea surface elevation and current velocity. Results indicate that the harbor's hydrodynamics are driven mainly by the tides, with wind and river inputs playing only small roles. The M2 tide is dominant, with amplitude 1.7 m and peak current speed 3.0 m s-1. Sensitivity tests using the model indicate that the mangrove areas and tidal flats play crucial roles in modulating tidal amplitudes and phases in the embayments, especially for the shallow water tides such as M4. Removal of the mangrove areas and tidal flats from Darwin Harbour would dampen the M2 amplitude due to decreased shoaling effects but generate a 75.0% greater M4 amplitude in parts of the harbor. Mangrove areas and tidal flats also affect tidal asymmetry through the changing amplitudes and phases of mainly the M2 and M4 tides. In Darwin Harbour, tidal asymmetry, measured by elevation and current skewness, would increase by up to 100% if the mangrove areas were removed. If the tidal flats were removed as well, the increase would be 120%. Therefore, reclamation of the mangrove areas and tidal flats may cause sediment siltation as a result of increased flood dominance. Although this study is site-specific, the model and our findings have a wider applicability to the effects of mangrove areas and tidal flats on tides and sediment transport in harbors and estuaries.

  19. Tidal power in Norway; Maanekraft fra dypet

    Energy Technology Data Exchange (ETDEWEB)



    The world's first tidal power station is scheduled for stat-up in the spring of 2003. It is located in Kvalsundet, off Hammerfest, Norway. This is a pilot installation of a 300 kW tidal turbine at a depth of 50 metres. When fully developed in 2007, the tidal power plant will deliver 32 GWh per year. Hammerfest Stroem has patented the energy and the company hopes to be able to install similar power stations both in Norway and abroad. The potential worldwide is claimed to be more than 450 TWh per year.

  20. Exploitation of tidal power in the Bay of Cadiz: ancient tidal mills

    Directory of Open Access Journals (Sweden)

    José J. Alonso del Rosario


    Full Text Available Tidal mills were the main industrial activity in the Bay of Cadiz for centuries. They were the last step in the production of salt and flour made by grinding grains. They were installed along the shallow channels, called “caños”, around the Bay, where the frictional and geometrical effects are very strong. The authors have analyzed the propagation of the semidiurnal tidal waves along the Caño de Sancti Petri and the available tidal power in the area. The ancient tidal mills were located where the available tidal potential energy is highest, which ensured productivity for grinding salt and wheat in ancient times. Some considerations about the possibility of installing tidal power plants in the Bay of Cadiz now are given, which show that it could be a real and renewal alternative source of energy for the area.

  1. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.


    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by

  2. Accelerated tidal circularization via resonance locking in KIC 8164262 (United States)

    Fuller, Jim; Hambleton, Kelly; Shporer, Avi; Isaacson, Howard; Thompson, Susan


    Tidal dissipation in binary star and planetary systems is poorly understood. Fortunately, eccentric binaries known as heartbeat stars often exhibit tidally excited oscillations, providing observable diagnostics of tidal circularization mechanisms and time-scales. We apply tidal theories to observations of the heartbeat star KIC 8164262, which contains an F-type primary in a very eccentric orbit that exhibits a prominent tidally excited oscillation. We demonstrate that the prominent oscillation is unlikely to result from a chance resonance between tidal forcing and a stellar oscillation mode. However, the oscillation has a frequency and amplitude consistent with the prediction of resonance locking, a mechanism in which coupled stellar and orbital evolution maintain a stable resonance between tidal forcing and a stellar oscillation mode. The resonantly excited mode produces efficient tidal dissipation (corresponding to an effective tidal quality factor Q ∼ 5 × 104), such that tidal orbital decay/circularization proceeds on a stellar evolution time-scale.

  3. Tides and tidal harmonics at Umbharat, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Suryanarayana, A.; Swamy, G.N.

    A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...

  4. Tidal mixing in Dahej creek waters

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Sarma, R.V.

    of effluent discharge has been worked out. The allowable duration of discharge of the hypothetical effluent over a tidal cycle ensuring a specified minimum dilution has also been indicated to help optimise the degree of inplant treatment. The results suggested...

  5. Morphodynamics of tidal networks: advances and challenges (United States)

    Coco, G.; Olabarrieta, M.; van Maanen, B.; Zhou, Z.; Tinoco, R.


    Tidal embayments are complex environments at the boundary between land and sea. Their evolution, natural or human-induced, feeds back onto ecological, economic and societal functions. Overall, the ability to manage tidal embayments successfully and maintain their value hinges on our knowledge of the system. The morphological behaviour of tidal embayments, however, is very complex because of the variety of feedback mechanisms which lead to morphological change. In recent years, numerical studies have highlighted that the feedback between the hydrodynamics, sediment transport and morphological evolution can lead to the development of tidally-forced morphological networks characterized by slowly-evolving bifurcating channels. Both tidal range and the initial bathymetry appear to have a strong control on the morphological characteristics of the tidal network by affecting final basin hypsometry and channel patterns. Although promising, none of the numerical models presented in the literature and capable of simulating the growth of a tidal network have been scrutinized against field or laboratory data. Here, we show and discuss the performance of one of those numerical models against detailed laboratory data. Preliminary results indicate that numerical simulations can reproduce the general features of pattern development but that a better description of many fast- and small-scale processes is needed to achieve better model-data agreement. Unsurprisingly, the model shows a strong sensitivity to frictional effects and resuspension parameterizations. Numerical models of morphodynamics tend to neglect some physical or biological processes that affect the short- and long-term evolution of tidal networks. In terms of physical processes, wind waves, interacting with the ebb shoal and tidal currents at the mouth of the embayment can significantly affect hydro- and morphodynamics. Under high wave conditions waves can break in the inlet area producing wave induced circulation

  6. Multiple Organ Disfonksiyonu Sendromu ve mekanik ventilasyon


    Eroğlu, Füsun; Yavuz, Lütfi; UÇAR, Ayşegül


    SüleymanDemirel Üniversitesi TIP FAKÜLTESİ DERGİSİ: 2004 Mart; 11(1) Multiple Organ Disfonksiyonu Sendromu ve mekanik ventilasyon Fusun Eroglu, Lutfi Yavuz, Aysegul Ucar Özet Sistemik inflamatuar cevap sendromu ve multiple organ disfonksiyonu sendromu (MODS) yoğun bakım ünitelerinde karşılaşılan ortak bir sendromdur. Etkili bir önleme ve tedavi yöntemi henüz bulunamamıştır. Yüksek mortalite oranları erken tanı ve k...

  7. Tidal Dissipation in Hot Jupiter Atmospheres (United States)

    Johnson, Eric T.


    Short-period extrasolar giant planets (hot Jupiters) experience periods of strong tidal dissipation. It is not well known whether tidal energy is deposited primarily in the deep interior or the surface layers of these planets, or what effect the location of tidal heating has on their evolution and observable properties (e.g. radii, spectra, and rate of mass loss in a planetary wind). I present a study of the local tidal heating rate as a function of latitude and depth in the radiative envelope and atmosphere (between pressure levels of about 1 kilobar and 0.001 microbars). Results are based on a nonadiabatic linear analysis of the tide in this region, which takes the form of an upward-propagating train of inertial-gravity waves excited at the interface between the convective interior and the stably-stratified envelope. Radiative damping dominates the dissipation. Careful attention is paid to the computation of the radiative relaxation timescale, using nongray radiative transfer to transition smoothly from the optically thick to the optically thin regime. The potential exists for conversion from inertial-gravity waves to pure inertial waves in the presence of strong radiative damping. This raises the possibility that a significant tidal energy flux can be transported as high as the base of the thermosphere, where it would contribute to driving atmospheric escape. Results can be used to chart local tidal heating rates over the lifetime of a hot Jupiter as its orbit and rotation rate evolve. Although the potential for high-altitude tidal heating is intriguing, I find that over a wide range of orbital parameters the bulk of the energy flux is dissipated nearer the IR photosphere. Tidal heating at those heights (around 0.1-10 bars) has the greatest potential to affect the emergent spectrum, and is least likely to slow the planet's rate of contraction.

  8. Ocean renewable energy : Tidal power in the Yellow Sea


    Lee, Han Soo


    Ocean renewable energy sources are briefly introduced in this review article. Special focus on tidal energy from ocean renewable energy in the Yellow Sea and its practical utilization in South Korea are illustrated with several examples. Among them, the Sihwa Lake tidal power plant, the Garolim Bay tidal power project, the Incheon tidal power project, and the Uldolmok tidal current power station were introduced with more details. A numerical modelling system, Regional Ocean Tide Simulator, is...

  9. Spatial patterns of tidal heating

    CERN Document Server

    Beuthe, Mikael


    In a body periodically strained by tides, heating produced by viscous friction is far from homogeneous. I show here that the distribution of the dissipated power within a spherically stratified body is a linear combination of three angular functions. These angular functions depend only on the tidal potential whereas the radial weights are specified by the internal structure of the body. The 3D problem of predicting spatial patterns of dissipation at all radii is thus reduced to the 1D problem of computing weight functions. I compute spatial patterns in various toy models without assuming a specific rheology: a viscoelastic thin shell stratified in conductive and convective layers, an incompressible homogeneous body and a two-layer model of uniform density with a liquid or rigid core. For a body in synchronous rotation undergoing eccentricity tides, dissipation in a mantle surrounding a liquid core is highest at the poles. Within a softer layer (asthenosphere or icy layer), the same tides generate maximum heat...

  10. Cassini Can Constrain Tidal Dissipation in Saturn (United States)

    Luan, Jing; Fuller, Jim; Quataert, Eliot


    Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parameterized equilibrium tidal the- ory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, Lainey et al. (2017) find that some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Reso- nance locking between satellites and internal oscillations of Saturn, proposed by Fuller et al. (2016), naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn’s gravita- tional field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini’s proximal orbits if migra- tion of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

  11. Half Moon Cove Tidal Project. Feasibility report

    Energy Technology Data Exchange (ETDEWEB)


    The proposed Half Moon Cove Tidal Power Project would be located in a small cove in the northern part of Cobscook Bay in the vicinity of Eastport, Maine. The project would be the first tidal electric power generating plant in the United States of America. The basin impounded by the barrier when full will approximate 1.2 square miles. The average tidal range at Eastport is 18.2 feet. The maximum spring tidal range will be 26.2 feet and the neap tidal range 12.8 feet. The project will be of the single pool-type single effect in which generation takes place on the ebb tide only. Utilizing an average mean tidal range of 18.2 feet the mode of operation enables generation for approximately ten and one-half (10-1/2) hours per day or slightly in excess of five (5) hours per tide. The installed capacity will be 12 MW utilizing 2 to 6 MW units. An axial flow, or Bulb type of turbine was selected for this study.

  12. Global tidal variations, regional distribution of ventilation, and the regional onset of filling determined by electrical impedance tomography: reproducibility. (United States)

    Caruana, L R; Barnett, A G; Tronstad, O; Paratz, J D; Chang, A T; Fraser, J F


    The reproducibility of the regional distribution of ventilation and the timing of onset of regional filling as measured by electrical impedance tomography lacks evidence. This study investigated whether electrical impedance tomography measurements in healthy males were reproducible when electrodes were replaced between measurements. Part 1: Recordings of five volunteers lying supine were made using electrical impedance tomography and a pneumotachometer. Measurements were repeated at least three hours later. Skin marking ensured accurate replacement of electrodes. No stabilisation period was allowed. Part 2: Electrical impedance tomography recordings of ten volunteers; a 15 minute stabilisation period, extra skin markings, and time-averaging were incorporated to improve the reproducibility. Reproducibility was determined using the Bland-Altman method. To judge the transferability of the limits of agreement, a Pearson correlation was used for electrical impedance tomography tidal variation and tidal volume. Tidal variation was judged to be reproducible due to the significant correlation between tidal variation and tidal volume (r2 = 0.93). The ventilation distribution was not reproducible. A stabilisation period, extra skin markings and time-averaging did not improve the outcome. The timing of regional onset of filling was reproducible and could prove clinically valuable. The reproducibility of the tidal variation indicates that non-reproducibility of the ventilation distribution was probably a biological difference and not measurement error. Other causes of variability such as electrode placement variability or lack of stabilisation when accounted for did not improve the reproducibility of the ventilation distribution.

  13. Stratification and loading of fecal indicator bacteria (FIB) in a tidally muted urban salt marsh. (United States)

    Johnston, Karina K; Dorsey, John H; Saez, Jose A


    Stratification and loading of fecal indicator bacteria (FIB) were assessed in the main tidal channel of the Ballona Wetlands, an urban salt marsh receiving muted tidal flows, to (1) determine FIB concentration versus loading within the water column at differing tidal flows, (2) identify associations of FIB with other water quality parameters, and (3) compare wetland FIB concentrations to the adjacent estuary. Sampling was conducted four times during spring-tide events; samples were analyzed for FIB and turbidity (NTU) four times over a tidal cycle at pre-allocated depths, depending on the water level. Additional water quality parameters measured included temperature, salinity, oxygen, and pH. Loadings were calculated by integrating the stratified FIB concentrations with water column cross-sectional volumes corresponding to each depth. Enterococci and Escherichia coli were stratified both by concentration and loading, although these variables portrayed different patterns over a tidal cycle. Greatest concentrations occurred in surface to mid-strata levels, during flood tides when contaminated water flowed in from the estuary, and during ebb flows when sediments were suspended. Loading was greatest during flood flows and diminished during low tide periods. FIB concentrations within the estuary often were significantly greater than those within the wetland tide channel, supporting previous studies that the wetlands act as a sink for FIB. For public health water quality monitoring, these results indicate that more accurate estimates of FIB concentrations would be obtained by sampling a number of points within a water column rather than relying only on single surface samples.

  14. Anterior Cingulate Volumetric Alterations in Treatment-Naïve Adults With ADHD (United States)

    Makris, Nikos; Seidman, Larry J.; Valera, Eve M.; Biederman, Joseph; Monuteaux, Michael C.; Kennedy, David N.; Caviness, Verne S.; Bush, George; Crum, Katherine; Brown, Ariel B.; Faraone, Stephen V.


    Objective We sought to examine preliminary results of brain alterations in anterior cingulate cortex (ACC) in treatment-naïve adults with ADHD. The ACC is a central brain node for the integration of cognitive control and allocation of attention, affect and drive. Thus its anatomical alteration may give rise to impulsivity, hyperactivity and inattention, which are cardinal behavioral manifestations of ADHD. Method Segmentation and parcellation of the ACC was performed on controls (n = 22), treated (n = 13) and treatment-naïve adults with ADHD (n = 13). Results There was a 21% volume reduction in the left ACC of the treatment-naïve group relative to the control group. Also, there was a 23% volume reduction in the right ACC of the treated group relative to the control group. Conclusion These results raise the possibility that in ADHD there are volumetric deficits persistent into adulthood, that are independent of medical treatment. PMID:20008822

  15. Three-dimensional semi-idealized model for tidal motion in tidal estuaries

    NARCIS (Netherlands)

    Kumar, M.; Schuttelaars, H.M.; Roos, P.C.; Möller, M.


    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the

  16. Seasonal variability of tidal and non-tidal currents off Beypore, SW coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DineshKumar, P.K.; Srinivas, K.; AnilKumar, N.

    Analyses of current meter records generated in the coastal waters off Beypore (11 degrees 10 minutes S; 75 degrees 48 minutes E) on the southwest coast of India have been made to understand the tidal and non-tidal variability during premonsoon...

  17. A comparative study of nitrogen and phosphorus cycling in tidal and non-tidal riverine wetlands

    NARCIS (Netherlands)

    Verhoeven, J. T.A.; Whigham, D.F.; van Logtestijn, R.; O'Neill, J.K.


    This paper describes a study of nutrient dynamics in 12 tidal and non-tidal freshwater riverine wetlands in The Netherlands, Belgium, and Maryland (USA). The purpose of the study was to investigate the relationships between nutrient cycling processes in riverine wetlands that were geographically

  18. Bio-geomorphic effects on tidal channel evolution: impact of vegetation establishment and tidal prism change

    NARCIS (Netherlands)

    Vandenbruwaene, W.; Meire, P.; Temmerman, S.; Bouma, T.J.


    The long-term (10–100 years) evolution of tidal channels is generally considered to interact with the bio-geomorphic evolution of the surrounding intertidal platform. Here we studied how the geometric properties of tidal channels (channel drainage density and channel width) change as (1) vegetation

  19. VE for Lua game programming

    CERN Document Server

    Mishra, Brij Bhushan


    This book follows a tutorial approach with examples and step-by-step instructions to help explain the key concepts of the LÖVE framework as well as everything you need to know about game development using the Lua programming language.LÖVE2d for Lua Game Programming is for anyone who is interested in learning about desktop game development.

  20. Tidal streams in the local group and beyond observations and implications

    CERN Document Server

    Carlin, Jeffrey


    This volume is written by leading scientists in the field, who review the current state of our knowledge of tidal streams in the Milky Way, the Andromeda galaxy, and in other nearby galaxies.  The cosmological origins of dwarf galaxies and the physical processes by which they are tidally disrupted into streams and incorporated into galaxy halos are discussed. The techniques that have been used to identify tidal streams are presented, and will be useful to researchers who would like to find substructures in the next generation of optical sky surveys, including Pan-STARRS and LSST.  The methods that are currently under development to constrain both large scale distribution of dark matter in the Milky Way and the (small scale) lumpiness of the dark matter distribution are also explained.  The authors also provide motivation for future spectroscopic surveys of Milky Way halo stars, which will aid both in the identification of tidal streams and the constraint of dark matter properties.This volume is aimed at g...

  1. Mo(ve)ment-methodology

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Christian Celosse-Andersen, Martin


    of major identity formation and gang exit processes, done together with a former biker gang member, Martin, becoming a research apprentice and more academically reflective, while moving beyond gang involvement. The paper empirically exemplifies the mo(ve)ment methodology presenting and analyzing one...... experienced moment called “Sp(l)itting on the street”. It is a moment which captures multiple and double feelings of conflictual concerns, frustrations, anger, a new feeling of insecurity of masculinity, as well as the feeling of engagement and deep meaningfulness, when becoming a more reflective academic....... These various conflictual feelings, also includes a sense of being split into conflicting identities. The paper analyzes how such conflictual feelings also can be productive, and produce movements and change in identity formation through our social practice research analysis and joint venture. The analyzed...

  2. Genève Reconnaissante

    CERN Multimedia


    Robert Cailliau (centre), with Geneva's Mayor Alain Vaissade (left) and Jean Erhardt, Secretary General of the Administrative Council of Geneva (right). Geneva recognised the contribution of two CERN people to the reputation of the city last Tuesday when Mayor Alain Vaissade presented the Genève Reconaissante Medal to Tim Berners-Lee and Robert Cailliau. Berners-Lee, who was not able to be present in person, invented the World Wide Web at CERN just over a decade ago, while Cailliau was his first collaborator. Quoting Cailliau, Vaissade said that whilst there is no doubt that something like the Web would have appeared sooner or later, the fact that it happened at CERN, in Geneva, was no accident. Both the Laboratory and the city are places where people from around the world meet and work in harmony.

  3. Orbital frontal cortex in treatment naïve pediatric obsessive-compulsive disorder


    MacMaster, Frank; Vora, Anvi; Easter, Phillip; Rix, Carrie; Rosenberg, David


    The orbital frontal cortex (OFC) has been implicated in obsessive-compulsive disorder (OCD). Twenty-eight treatment-naïve pediatric OCD patients and twenty-one controls were examined using magnetic resonance imaging. OCD patients had larger right but not left OFC white matter volume than controls. This is fresh evidence implicating white matter in OCD.

  4. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.


    Australia\\'s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia\\'s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia\\'s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  5. On the migration rate of tidal meanders (United States)

    D'Alpaos, A.; Finotello, A.; Ghinassi, M.; Lanzoni, S.; Marani, M.; Rinaldo, A.


    Sinuous channels shaped by periodically reversing tidal flows are a ubiquitous feature of tidal landscapes. Despite their fundamental role on the morphology and sedimentary patterns of these landscapes, tidal meanders have received less attention than their fluvial counterparts, particularly as far as migration processes are concerned. We have analyzed the migration of about 300 meander bends in the Northern Venice Lagoon (Italy), from 1968 to nowadays, through observations and modeling interpretation. Similarities with fluvial meanders occur, although important difference also emerge. Meanders cutting through salt-marshes in the Venice Lagoon follow the relationship between Cartesian length and channel width, typical of meanders developed within different settings. We find a mean migration rate of about 0.20 m/year. However, the potential migration rate can reach values of about 0.20 channel widths per year thus suggesting similarities with fluvial meanders. In addition, tidal channel migration dynamics displays features which qualitatively agree with theories developed for the fluvial setting. We deem our results are valuable for the understanding of the morphological evolution and architecture of tidal landscapes, with implications for restoration strategies, also in the face of changes in environmental conditions.

  6. Carbon sequestration by Australian tidal marshes (United States)

    Macreadie, Peter I.; Ollivier, Q. R.; Kelleway, J. J.; Serrano, O.; Carnell, P. E.; Ewers Lewis, C. J.; Atwood, T. B.; Sanderman, J.; Baldock, J.; Connolly, R. M.; Duarte, C. M.; Lavery, P. S.; Steven, A.; Lovelock, C. E.


    Australia’s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia’s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia’s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  7. The wave and tidal resource of Scotland (United States)

    Neill, Simon; Vogler, Arne; Lewis, Matt; Goward-Brown, Alice


    As the marine renewable energy industry evolves, in parallel with an increase in the quantity of available data and improvements in validated numerical simulations, it is occasionally appropriate to re-assess the wave and tidal resource of a region. This is particularly true for Scotland - a leading nation that the international community monitors for developments in the marine renewable energy industry, and which has witnessed much progress in the sector over the last decade. With 7 leased wave and 17 leased tidal sites, Scotland is well poised to generate significant levels of electricity from its abundant natural marine resources. In this review of Scotland's wave and tidal resource, I present the theoretical and technical resource, and provide an overview of commercial progress. I also discuss issues that affect future development of the marine energy seascape in Scotland, applicable to other regions of the world, including the potential for developing lower energy sites, and grid connectivity.


    Energy Technology Data Exchange (ETDEWEB)

    Thomson, Jim; Kilcher, Levi; Richmond, Marshall C.; Talbert, Joe; deKlerk, Alex; Polagye, Brian; Guerra, Maricarmen; Cienfuegos, Rodrigo


    A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demon- stration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspend- ing Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion cor- rection (post-processing), data quality is further improved; the relative merits of direct and spectral motion correction are dis- cussed.

  9. Circumbinary discs from tidal disruption events (United States)

    Coughlin, Eric R.; Armitage, Philip J.


    Tidal disruption events, which occur when a star is shredded by the tidal field of a supermassive black hole (SMBH), provide a means of fuelling black hole accretion. Here we show, using a combination of three-body orbit integrations and hydrodynamic simulations, that these events are also capable of generating circumbinary rings of gas around tight SMBH binaries with small mass ratios. Depending on the thermodynamics, these rings can either fragment into clumps that orbit the binary, or evolve into a gaseous circumbinary disc. We argue that tidal disruptions provide a direct means of generating circumbinary discs around SMBH binaries and, more generally, can replenish the reservoir of gas on very small scales in galactic nuclei.

  10. CDNA cloning and characterization of the Ve homologue gene StVe from Solanum torvum Swartz. (United States)

    Fei, Jiong; Chai, Yourong; Wang, Jin; Lin, Juan; Sun, Xiaofen; Sun, Chao; Zuo, Kaijing; Tang, Kexuan


    Verticillium wilt is a disastrous disease causing significant yield losses of many crops. Isolation of verticillium wilt resistance gene is a fundamental work for controlling this disease through genetic engineering. In this report, we describe the cloning and characterization of a Ve like gene (StVe) from Solanum torvum Swartz. The nucleotide sequence of StVe is 3640 bp long with an open reading frame of 3414 bp encoding a protein precursor of 1138 aa. Sharing high homologies to tomato verticillium wilt disease resistance genes Ve1 and Ve2, the leucine rich (15.89%) protein StVe has a calculated molecular weight of 126.48kDa with an isoelectric point of 5.62. It possesses a hydrophobic N-terminal signal peptide of 20 aa and 38 predicted leucine-rich repeats containing 32 potential N-glycosylation sites (28 being significant). Fifty-seven predicted phosphorylation sites (36 for S, 8 for T and 13 for Y) distribute in StVe protein. A PEST-like sequence and a mammalian endocytosis signals YCVF are found within the C-terminal region. The C terminus of StVe concludes with the residues KKF similar to the KKX motif that confers endoplasmic reticulum localization in plants as well as mammals and yeast. The sequence analysis of the StVe gene implies that the StVe is a potential verticillium wilt disease resistance gene encoding a cell surface-like receptor protein.

  11. Correlation between seismicity and barometric tidal exalting

    Directory of Open Access Journals (Sweden)

    D. N. Arabelos


    Full Text Available Changes of barometric pressure in the area of Thessaloniki in Northern Greece were studied by analyzing a sample of 31 years of hourly measurements. The results of this analysis on the periodicities of tidal components are expressed in terms of amplitude and phases variability. An earlier investigation revealed a detectable correlation between the exalting of the amplitude parameters of the tidal waves with strong seismic events. A problem of this work was that we had compared the tidal parameters resulting from the analysis of data covering the period of one year with instantaneous seismic events, although the earthquake is the final result of a tectonic process of the upper lithosphere. Consequently, in order to increase the resolution of our method we had analyzed our data in groups of 3-months extent and the resulted amplitudes were compared with seismicity index for corresponding time periods. A stronger correlation was found in the last case. However, the estimation of tidal parameters in this case was restricted to short period (from one day down to eight hours constituents. Therefore, a new analysis was performed, retaining the one-year length of each data block but shifting the one year window by steps of three months from the beginning to the end of the 31 years period. This way, we are able to estimate again tidal parameters ranging from periods of one year (Sa down to eight hours (M3. The resulting correlation between these tidal parameters with a cumulative seismicity index for corresponding time intervals was remarkably increased.


    Energy Technology Data Exchange (ETDEWEB)

    Kite, Edwin S.; Manga, Michael [Department of Earth and Planetary Science, University of California at Berkeley, CA 94720 (United States); Gaidos, Eric, E-mail: [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)


    Feedbacks that can destabilize the climates of synchronously rotating rocky planets may arise on planets with strong day-night surface temperature contrasts. Earth-like habitable planets maintain stable surface liquid water over geologic time. This requires equilibrium between the temperature-dependent rate of greenhouse-gas consumption by weathering, and greenhouse-gas resupply by other processes. Detected small-radius exoplanets, and anticipated M-dwarf habitable-zone rocky planets, are expected to be in synchronous rotation (tidally locked). In this paper, we investigate two hypothetical feedbacks that can destabilize climate on planets in synchronous rotation. (1) If small changes in pressure alter the temperature distribution across a planet's surface such that the weathering rate goes up when the pressure goes down, a runaway positive feedback occurs involving increasing weathering rate near the substellar point, decreasing pressure, and increasing substellar surface temperature. We call this feedback enhanced substellar weathering instability (ESWI). (2) When decreases in pressure increase the fraction of surface area above the melting point (through reduced advective cooling of the substellar point), and the corresponding increase in volume of liquid causes net dissolution of the atmosphere, a further decrease in pressure will occur. This substellar dissolution feedback can also cause a runaway climate shift. We use an idealized energy balance model to map out the conditions under which these instabilities may occur. In this simplified model, the weathering runaway can shrink the habitable zone and cause geologically rapid 10{sup 3}-fold atmospheric pressure shifts within the habitable zone. Mars may have undergone a weathering runaway in the past. Substellar dissolution is usually a negative feedback or weak positive feedback on changes in atmospheric pressure. It can only cause runaway changes for small, deep oceans and highly soluble atmospheric

  13. Tidal forces in Kiselev black hole

    Energy Technology Data Exchange (ETDEWEB)

    Shahzad, M.U. [University of Central Punjab, CAMS, UCP Business School, Lahore (Pakistan); Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)


    The aim of this paper is to examine the tidal forces occurring in a Kiselev black hole surrounded by radiation and dust fluids. It is noted that the radial and angular components of the tidal force change the sign between event and Cauchy horizons. We solve the geodesic deviation equation for radially free-falling bodies toward Kiselev black holes. We explain the geodesic deviation vector graphically and point out the location of the event and Cauchy horizons for specific values of the radiation and dust parameters. (orig.)

  14. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline


    The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

  15. Short period tidal variations of earth rotation (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.; Dickey, J. O.


    It is explained that the tidal deformation of the earth's polar moment of inertia by the moon and sun cause periodic variations in rotation. The short period oscillations give rise to a meter-sized, diurnal signature in the lunar laser ranging data obtained at McDonald Observatory. A solution is given for the scale parameter k/C at fortnightly and monthly tidal frequencies. The results are compared with those obtained by other investigators and with a theoretical estimate which includes the effect of oceans and a decoupled fluid core.

  16. Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars (United States)

    Garling, Christopher; Willman, Beth; Sand, David J.; Hargis, Jonathan; Crnojević, Denija; Bechtol, Keith; Carlin, Jeffrey L.; Strader, Jay; Zou, Hu; Zhou, Xu; Nie, Jundan; Zhang, Tianmeng; Zhou, Zhimin; Peng, Xiyan


    We investigate the hypothesized tidal disruption of the Hercules ultra-faint dwarf galaxy (UFD). Previous tidal disruption studies of the Hercules UFD have been hindered by the high degree of foreground contamination in the direction of the dwarf. We bypass this issue by using RR Lyrae stars, which are standard candles with a very low field-volume density at the distance of Hercules. We use wide-field imaging from the Dark Energy Camera on CTIO to identify candidate RR Lyrae stars, supplemented with observations taken in coordination with the Beijing–Arizona Sky Survey on the Bok Telescope. Combining color, magnitude, and light-curve information, we identify three new RR Lyrae stars associated with Hercules. All three of these new RR Lyrae stars lie outside its published tidal radius. When considered with the nine RR Lyrae stars already known within the tidal radius, these results suggest that a substantial fraction of Hercules’ stellar content has been stripped. With this degree of tidal disruption, Hercules is an interesting case between a visibly disrupted dwarf (such as the Sagittarius dwarf spheroidal galaxy) and one in dynamic equilibrium. The degree of disruption also shows that we must be more careful with the ways we determine object membership when estimating dwarf masses in the future. One of the three discovered RR Lyrae stars sits along the minor axis of Hercules, but over two tidal radii away. This type of debris is consistent with recent models that suggest Hercules’ orbit is aligned with its minor axis.

  17. 2nd Workshop on Tidal Friction and the Earth's Rotation

    CERN Document Server

    Sündermann, Jürgen


    In the four years which elapsed between our first workshop on .Tidal Friction and the Earth's Rotation and the second, the proceedings of which are presented here, many of the disciplines involved made ad­ vances which we felt should be exchanged. We were encouraged by the good reception our first report met with. Of course, more insight often means more problems. Therefore, this volume contains new results and revisions of matters which previously appeared settled. We are certainly far from "final answers". For this reason, differing opinions on some issues are to be found in this book. Moreover, we have refrained from making mathematical symbols uniform to avoid the risk of errors and non-compatibility with the earlier work of an author. The two workshops have stimulated collaboration between participants working in various fields. The final versions of the contributions have already profited from these discussions. We are convinced that they will also influence further investigations. This advancement of ...

  18. Spatial tidal asymmetry of Cochin estuary, West Coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Vinita, J.; Shivaprasad, A.; Manoj, N.T.; Revichandran, C.; Naveenkumar, K.R.; Jineesh, V.K.

    tidal amplitude and currents get attenuated towards upstream through frictional dissipation The results showed that the tidal momentum balance along the main axis of the channel was dominated by pressure gradient and friction The influence of advection...

  19. NOAA Historical Tidal Current Data for the Coastal United States (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  20. Tidal flow characteristics at Kasheli (Kalwa/ Bassein creek), Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Suryanarayana, A.

    Tidal flow characteristics of waters at Kasheli, connected to the sea through Thane and Bassein Creeks in Bombay, Maharashtra, India are investigated based on tide and current observations carried out in 1980-81. The results establish that the tidal...

  1. NOAA Tidal Current Data for the Coastal United States (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  2. Abnormal end-tidal PO(2) and PCO(2) at the anaerobic threshold correlate well with impaired exercise gas exchange in patients with left ventricular dysfunction. (United States)

    Kano, Hiroto; Koike, Akira; Hoshimoto-Iwamoto, Masayo; Nagayama, Osamu; Sakurada, Koji; Suzuki, Takeya; Tsuneoka, Hidekazu; Sawada, Hitoshi; Aizawa, Tadanori; Wasserman, Karlman


    The aim of the present study was to compare the end-tidal O(2) pressure (PETO(2)) to end-tidal CO(2) pressure (PETCO(2)) in cardiac patients during rest and during 2 states of exercise: at anaerobic threshold (AT) and at peak. The purpose was to see which metabolic state, PETO(2) or PETCO(2), best correlated with exercise limitation. Thirty-eight patients with left ventricular (LV) ejection fraction exercise testing (CPX). PETO(2) and PETCO(2) were measured during CPX, along with peak O(2) uptake (VO(2)), AT, slope of the increase in ventilation (VE) relative to the increase in CO(2) output (VCO(2)) (VE vs. VCO(2) slope), and the ratio of the increase in VO(2) to the increase in work rate (ΔVO(2)/ΔWR). Both PETO(2) and PETCO(2) measured at AT were best correlated with peakVO(2), AT, ΔVO(2)/ΔWR and VE vs. VCO(2) slope. PETO(2) at AT correlated with reduced peak VO(2) (r=-0.60), reduced AT (r=-0.52), reduced ΔVO(2)/ΔWR (r=-0.55) and increased VE vs. VCO(2) slope (r=0.74). PETCO(2) at AT correlated with reduced peak VO(2) (r=0.67), reduced AT (r=0.61), reduced ΔVO(2)/ΔWR (r=0.58) and increased VE vs. VCO(2) slope (r=-0.80). PETCO(2) and PETO(2) at AT correlated with peak VO(2), AT and ΔVO(2)/ΔWR, but best correlated with increased VE vs. VCO(2) slope. PETO(2) and PETCO(2) at AT can be used as a prime index of impaired cardiopulmonary function during exercise in patients with LV failure.



    Kamran Ahmed Samo*1, Andrew Ragai Henry Rigit2, Imran Ahmed Samo3, Abid Ali Shah Bukhari 4, Ahsanullah Soomro5, Azhaili Baharun6


    Renewable energy is the best solution and alternative to overcome the world growing energy demand and fossil fuels deficiency. Tidal energy is also renewable energy that uses barrage and tide height difference to extract energy. Kuching Barrage located in Sarawak was built to mitigate flood in the city of Kuching and has the potential for development into tidal power station. The purpose of this paper is to offer suitable tidal power plant system for tidal energy harnessing at Kuching Barrage...

  4. Quantification of tidal parameters from Solar system data


    Lainey, Valéry


    Tidal dissipation is the main driver of orbital evolution of natural satellites and a key point to understand the exoplanetary system configurations. Despite its importance, its quantification from observations still remains difficult for most objects of our own Solar system. In this work, we overview the method that has been used to determine, directly from observations, the tidal parameters, with emphasis on the Love number k2 and the tidal quality factor Q. Up-to-date values of these tidal...

  5. Tidal Power Potential in the Submerged Channels of Dar es

    African Journals Online (AJOL)

    Results from in-situ measurements show that currents on the sandbank and the tidal flat, in water depths from 0.5 m to 3.0 m, are directed opposite the main tidal current in the deeper waters. Current velocities vary during a tidal cycle and are strongest in the middle of the cycle. Generally, velocities on the tidal flat are around ...

  6. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak İçindekiler


    Full Text Available Zentralblatt MATH, Chemical Abstract, CAB Abstract ve EBSCO Host indeksleri tarafından taranmaktadır. Indexed in Zentralblatt MATH, Chemical Abstract, CAB Abstract and EBSCO Host indexes

  7. Subtidal flow division at a shallow tidal junction

    NARCIS (Netherlands)

    Buschman, F.A.; Hoitink, A.J.F.; Vegt, van der M.; Hoekstra, P.


    Tides influence distribution of river discharge at tidally affected channel junctions. At the apex of a channel network in an Indonesian delta, observations of flow division suggest that tidally averaged flow division depends on the tidal range. To understand the mechanisms governing the subtidal

  8. How Tidal Forces Cause Ocean Tides in the Equilibrium Theory (United States)

    Ng, Chiu-king


    We analyse why it is erroneous to think that a tidal bulge is formed by pulling the water surface directly up by a local vertical tidal force. In fact, ocean tides are caused by the global effect of the horizontal components of the tidal forces.

  9. Sedimentary signatures of tidal bores: a brief synthesis (United States)

    Tessier, Bernadette; Furgerot, Lucille; Mouazé, Dominique


    This article aims at presenting a brief synthesis of sedimentary signatures assigned to tidal bore dynamics and impacts. According to the few studies published until now on tidal bore-induced facies within inner estuarine tidal channel infilling successions, only two major signatures can be reported: (1) soft sediment deformations (SSDs) due to overpressure linked to sudden water level elevation, high shear stress and vertical velocity acceleration below the tidal bore front and secondary waves; SSDs may be present throughout the channel infill succession, with the general exception of the uppermost part; tidal bore-induced SSDs have been described only in modern facies; (2) tidal bore couplets (TBCs) formed by an erosional surface overlain by massive sand drapes, related to the reworking of the sediment bottom during tidal bore passage; TBCs were first described in the ancient record. Studies in modern estuaries demonstrate that TBCs evolve towards tidal bore sequences from the tidal channel bottom (subtidal to low intertidal facies) to tidal channel bank (low to mid intertidal facies). In mid to upper intertidal facies, the occurrence of thicker-than-average tidal rhythmites, reflecting higher-than-average suspended sediment concentrations, are also considered as a possible signature of tidal bore dynamics.

  10. Ecological consequences of diurnal flooding in tidal freshwater wetlands

    NARCIS (Netherlands)

    Barendregt, A.; Wassen, M.J.


    Diurnal flooding can be observed in the upper end of tidal estuaries, where flooding water originating from the river is constantly fresh. Here, the input from the river is confronted with a tidal wave, so that the sand banks, mud flats, low and high marshes and tidal forests are flooded mostly

  11. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  12. Geometry of tidal inlet systems : A key factor for the net sediment transport in tidal inlets

    National Research Council Canada - National Science Library

    Ridderinkhof, W; de Swart, H. E; van der Vegt, M; Alebregtse, N. C; Hoekstra, P


    .... Earlier studies showed that in a short basin, tidal flats favor peak ebb-currents stronger than peak flood currents, implying export of coarse sediment, while shallow basins favor stronger flood currents...

  13. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.


    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  14. Palaemon pacijicus (Stimpson) in eastern Cape tidal

    African Journals Online (AJOL)


    Sep 25, 1984 ... study of marine benthos, IBP Handbook 16: 197 - 279, (eds). Holme, N.A. & Mcintyre, A.D., Blackwell, Oxford. DAY, J.H. 1980. A guide to marine life on South African shores,. A.A. Balkema, Cape Town. EMMERSON, W.D. 1983. Tidal exchange of two decapod larvae. Palaemon pacijicus (Caridea) and ...

  15. Tidal Energy Dissipation from Topex/Poseidon (United States)

    Ray, Richard D.; Egbert, G. D.; Smith, David E. (Technical Monitor)


    In a recent paper ({\\it Nature, 405,} 775, 2000) we concluded that 25 to 30\\% of the ocean's tidal energy dissipation, or about 1 terawatt, occurs in the deep ocean, with the remaining 2.6 TW in shallow seas. The physical mechanism for deep-ocean dissipation is apparently scattering of the surface tide into internal modes; Munk and Wunsch have suggested that this mechanism may provide half the power needed for mixing the deep-ocean. This paper builds further evidence for $1\\pm 0.2$ TW of deep-ocean dissipation. The evidence is extracted from tidal elevations deduced from seven years of Topex/Poseidon satellite altimeter data. The dissipation rate Is formed as a balance between the rate of working by tidal forces and the energy flux divergence. While dynamical assumptions are required to compute fluxes, area integrals of the energy balance are, owing to the tight satellite constraints, remarkably insensitive to these assumptions. A large suite of tidal solutions based on a wide range of dynamical assumptions, on perturbations to bathymetric models, and on simulated elevation data are used to assess this sensitivity. These and Monte Carlo error fields from a generalized inverse model are used to establish error uncertainties.

  16. Reinterpreting The Sagittarius Dwarf Tidal Debris (United States)

    Newby, Matthew T.; Newberg, Heidi Jo; Thompson, Jeffery M.; Weiss, Jake


    Tidal debris from the Sagittarius dwarf galaxy (Sgr) has been used as a primary constraint in several determinations of the Milky Way Galaxy's total mass and dark matter distribution. However, the apparent "bifurcation" of both the leading and trailing tidal tails has never been satisfactorily explained. Using the powerful MilkyWay@home volunteer computing platform, we were surprised that the apparently fainter of the bifurcated tidal tails required an extremely wide stream to fit the observed stellar densities. Here, through additional analysis, we show that both the primary and secondary tidal tails of Sgr, as well as the Virgo overdensity, are all wider than previously thought, and dominate star counts in the Galactic halo. Additionally, we present evidence of a stellar "envelope" about the primary Sgr stream, which may be direct evidence for a subhalo-rich (or "lumpy") dark matter distribution. This research was supported by the NSF through grant AST 10-09670, and crowd funding from the MilkyWay@home volunteers.

  17. Tidal dwarf galaxies in cosmological simulations (United States)

    Ploeckinger, Sylvia; Sharma, Kuldeep; Schaye, Joop; Crain, Robert A.; Schaller, Matthieu; Barber, Christopher


    The formation and evolution of gravitationally bound, star forming substructures in tidal tails of interacting galaxies, called tidal dwarf galaxies (TDG), has been studied, until now, only in idealized simulations of individual pairs of interacting galaxies for pre-determined orbits, mass ratios and gas fractions. Here, we present the first identification of TDG candidates in fully cosmological simulations, specifically the high-resolution simulations of the EAGLE suite. The finite resolution of the simulation limits their ability to predict the exact formation rate and survival time-scale of TDGs, but we show that gravitationally bound baryonic structures in tidal arms already form in current state-of-the-art cosmological simulations. In this case, the orbital parameter, disc orientations as well as stellar and gas masses and the specific angular momentum of the TDG forming galaxies are a direct consequence of cosmic structure formation. We identify TDG candidates in a wide range of environments, such as multiple galaxy mergers, clumpy high-redshift (up to z = 2) galaxies, high-speed encounters and tidal interactions with gas-poor galaxies. We present selection methods, the properties of the identified TDG candidates and a road map for more quantitative analyses using future high-resolution simulations.

  18. Methane distribution in European tidal estuaries

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.; Iversen, N.; Høgh, N.; De Wilde, H.; Helder, W.; Seifert, R.; Christof, O.


    Methane concentrations have been measured along salinity profiles in nine tidal estuaries in Europe (Elbe, Ems, Thames, Rhine, Scheldt, Loire, Gironde, Douro and Sado). The Rhine, Scheldt and Gironde estuaries have been studied seasonally. A number of different methodologies have been used and they

  19. Estuaries and Tidal Marshes. Habitat Pac. (United States)

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    This educational packet consists of an overview, three lesson plans, student data sheets, and a poster. The overview examines estuaries and tidal or salt marshes by discussing the plants and animals in these habitats, marsh productivity, benefits and management of the habitats, historical aspects, and development and pollution. A glossary and list…

  20. Modelling the far field hydro-environmental impacts of tidal farms - A focus on tidal regime, inter-tidal zones and flushing (United States)

    Nash, S.; O'Brien, N.; Olbert, A.; Hartnett, M.


    The introduction of tidal stream turbines into water bodies can have an impact on the environment due to changes in the hydrodynamic flow fields resulting from the extraction of energy by the tidal turbines. Water levels, tidal currents and flushing characteristics could potentially be significantly altered with the introduction of tidal turbine farms, which could lead to possible loss of habitat and a change in the tidal regime. Therefore, planning of tidal turbines field deployments must take into account possible hydro-environmental impacts. This paper describes research undertaken by the authors in the Shannon Estuary to predict changes in the tidal regime and flushing characteristics, with the introduction of tidal turbine farms of different array configurations. The model was simulated using a 2D hydrodynamic model that was modified to incorporate the effects of tidal turbine fields. Water levels are shown to have been affected with the inclusion of turbines, especially in areas upstream of the turbine farm where inter-tidal zones could become predominately inundated resulting in loss of habitat in the estuary. Flushing parameters were also shown to be altered with the inclusion of turbines, with residence time shown to be increased, which could change pollutant transport in the region.

  1. 40 CFR 35.926 - Value engineering (VE). (United States)


    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Value engineering (VE). 35.926 Section... engineering (VE). (a) Value engineering proposal. All step 2 grant applications for projects having a... completion of VE analysis and submittal of VE summary reports). (b) Value engineering analysis. For projects...

  2. Investigating oceanic tidal energy dissipation on deep time scales using short tidal deposit sequences (United States)

    Coughenour, C.


    One of the enduring problems in physical oceanography has been that of tidal dynamics and the effective tidal torque that serves to slow Earth's axial rotation. In the late 20th century, with the aid of satellite altimetry and other technologies, a suite of reliable estimates was finally placed on the magnitude of this torque and other, related parameters in the current epoch. Tidal drag accounts for a 20 microsecond/year increase in mean day length, a 3.5 terawatt dissipation of energy in the oceans (Kantha et al., 1998), and a lunar retreat rate of 3.82 cm/yr (Dickey et al., 1994). Despite these significant advances, however, the problem of tidal dissipation in the geologic past remains largely unresolved. This is due, in part, to difficulties in numerical modeling of past tidal regimes that stem from uncertainties in ocean basin configurations and lunar distances. Tidal deposits can record, to high resolution, the primary astronomical periodicities responsible for the generation of the tidal currents under which transport and deposition occur. With reliable lunar orbital period data obtained from tidal deposits, the past Earth-Moon distance and length of day can be calculated. This task requires careful spectral analysis and consideration of sedimentological factors that may add noise and/or discontinuities to the signal. For deposits representing less than one year of deposition, the necessary assumptions are that Earth's moment of inertia has not changed significantly over the time interval of interest and that the solar component of tidal dissipation can be well-approximated. With consideration of the total angular momentum of the Earth-Moon couplet, we derive a method to calculate lunar distance and length of day. The efficacy of this method and its assumptions is tested via the multi-year sequence of data obtained from the late Precambrian Elatina Formation of Australia and comparing results obtained from the full suite of data by Williams (2000). We go on

  3. Gravitational tidal effects on galactic open clusters (United States)

    Bergond, G.; Leon, S.; Guibert, J.


    We have investigated the 2-D stellar distribution in the outer parts of three nearby open clusters: NGC 2287 (equiv M 41), NGC 2516, and NGC 2548 (equiv M 48). Wide-field star counts have been performed in two colours on pairs of digitized ESO and SRC Schmidt plates, allowing us to select likely cluster members in the colour-magnitude diagrams. Cluster tidal extensions were emphasized using a wavelet transform. Taking into account observational biases, namely the galaxy clustering and differential extinction in the Galaxy, we have associated these stellar overdensities with real open cluster structures stretched by the galactic gravitational field. As predicted by theory and simulations, and despite observational limitations, we detected a general elongated (prolate) shape in a direction parallel to the galactic Plane, combined with tidal tails extended perpendicularly to it. This geometry is due both to the static galactic tidal field and the heating up of the stellar system when crossing the Disk. The time varying tidal field will deeply affect the cluster dynamical evolution, and we emphasize the importance of adiabatic heating during the Disk-shocking. In the case of NGC 2548, our dating of the last shocking with the Plane (based on a tidal clump) is consistent with its velocity. During the 10-20 Z-oscillations experienced by a cluster before its dissolution in the Galaxy, crossings through the galactic Disk contribute to at least 15% of the total mass loss. Using recent age estimations published for open clusters, we find a destruction time-scale of about 600 Myr for clusters in the solar neighbourhood. Plate scanning was done at the Centre d'Analyse des Images (CAI) with M.A.M.A. (Machine Automatique àMesurer pour l'Astronomie), a facility located at the Observatoire de Paris, developed and operated by INSU (Institut National des Sciences de l'Univers, CNRS). Web site

  4. Tidal Tales II: Molecular Gas and Star Formation in the Tidal Tails of Minor Mergers (United States)

    Knierman, Karen A.; Scowen, Paul A.; Groppi, Christopher E.


    While major mergers and their tidal debris are well studied, equal mass galaxy mergers are relatively rare compared to minor mergers (mass ratio pivotal role in the formation of most large galaxies. Tidal debris regions have large amounts of neutral gas but a lower gas density and may have higher turbulence. We use star formation tracers such as young star cluster populations and H-alpha and CII emission to determine the different factors that may influence star formation in tidal debris. These tracers were compared to the reservoirs of molecular and neutral gas available for star formation to estimate the star formation efficiency (SFE). The SFR in tidal debris can reach up to 50% of the total star formation in the system. The SFE of tidal tails in minor mergers can range over orders of magnitude on both local and global scales. From the tidal debris environments in our study, this variance appears to stem from the formation conditions of the debris. Current surveys of the 2.12 micron line of molecular hydrogen, CO(1-0), and HI for 15 minor mergers, are providing a larger sample of environments to study the threshold for star formation that can inform star formation models, particularly at low densities.

  5. Tidal Tales of Minor Mergers: Star Formation in the Tidal Tails of Minor Mergers (United States)

    Knierman, Karen A.; Monkiewicz, Jacqueline A.; Scowen, Paul A.; Groppi, Christopher E.


    While major mergers and their tidal debris are well studied, equal mass galaxy mergers are relatively rare compared to minor mergers (mass ratio pivotal role in the formation of most large galaxies. Tidal debris regions have large amounts of neutral gas but a lower gas density and may have higher turbulence. We use star formation tracers such as young star cluster populations and H-alpha and CII emission to determine the different factors that may influence star formation in tidal debris. These tracers were compared to the reservoirs of molecular and neutral gas available for star formation to estimate the star formation efficiency (SFE). The SFR in tidal debris can reach up to 50% of the total star formation in the system. The SFE of tidal tails in minor mergers can range over orders of magnitude on both local and global scales, and include several star forming regions with higher than normal SFE. From the tidal debris environments in our study, this variance appears to stem from the formation conditions of the debris. Current surveys of the 2.12 micron line of molecular hydrogen, CO(1-0), and HI for 15 minor mergers, are providing a larger sample of environments to study the threshold for star formation that can inform star formation models, particularly at low densities.

  6. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height

    NARCIS (Netherlands)

    Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.


    This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export

  7. Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP (United States)

    Liu, Zhao-Jun; Nakamura, Hirohiko; Zhu, Xiao-Hua; Nishina, Ayako; Dong, Menghong


    Ferryboat Acoustic Doppler Current Profiler (ADCP) data from 2003 to 2012 are used to estimate the tidal and residual currents across the northern Ryukyu Island chain (RIC) between the islands of Okinawa and Amamioshima. In this region, the M2 tide current is the strongest tidal component, and the K1 tide current is the strongest diurnal tidal component. The corresponding maximum amplitudes are 40 and 34 cm s-1, respectively. After removal of the tidal currents, the mean volume transport, 1.5 ± 2.7 Sv, flows into the East China Sea (ECS) from the western North Pacific through four channels in this area. In an empirical orthogonal function (EOF) analysis performed to clarify the temporal and spatial variability of currents through the four channels, the first two EOF modes account for 71% and 18% of the total variance, respectively. The EOF1 mode shows a clear bottom-intensified mode through the deep channel, which is likely to be formed by the propagation of bottom-trapped long topographic Rossby wave caused by the impingement of westward-propagating mesoscale eddies upon the eastern slope of the northern RIC. The EOF2 mode has significant seasonal variability and may be driven by the wind stress prevailing over the Kuroshio flow region around the northern RIC in October-November. This study provides observational evidence of the water exchanges across the northern RIC, which is essential for constructing a circulation scheme in the North Pacific subtropical western boundary region.

  8. The physiological basis and clinical significance of lung volume measurements


    Lutfi, Mohamed Faisal


    From a physiological standpoint, the lung volumes are either dynamic or static. Both subclasses are measured at different degrees of inspiration or expiration; however, dynamic lung volumes are characteristically dependent on the rate of air flow. The static lung volumes/capacities are further subdivided into four standard volumes (tidal, inspiratory reserve, expiratory reserve, and residual volumes) and four standard capacities (inspiratory, functional residual, vital and total lung capaciti...

  9. VLT observations of NGC 1097's ``dog-leg'' tidal stream. Dwarf spheroidals and tidal streams (United States)

    Galianni, P.; Patat, F.; Higdon, J. L.; Mieske, S.; Kroupa, P.


    Aims: We investigate the structure and stellar population of two large stellar condensations (knots A & B) along one of the faint optical “jet-like” tidal streams associated with the spiral NGC 1097, with the goal of establishing their physical association with the galaxy and their origin. Methods: We use the VLT/FORS2 to get deep V-band imaging and low-resolution optical spectra of two knots along NGC 1097's northeast “dog-leg” tidal stream. With this data, we explore their morphology and stellar populations. Results: Spectra were obtained for eleven sources in the field surrounding the tidal stream. The great majority of them turned out to be background or foreground sources, but the redshift of knot A (and perhaps of knot B) is consistent with that of NGC 1097. Using the V-band image of the “dog-leg” tidal feature we find that the two knots match the photometric scaling relations of canonical dwarf spheroidal galaxies (dSph) very well. Spectral analysis shows that knot A is mainly composed of stars near G-type, with no signs of ongoing star formation. Comparing its spectrum with a library of high resolution spectra of galactic globular clusters (GCs), we find that the stellar population of this dSph-like object is most similar to intermediate to metal rich galactic GCs. We find moreover, that the tidal stream shows an “S” shaped inflection as well as a pronounced stellar overdensity at knot A's position. This suggests that knot A is being tidally stripped, and populating the stellar stream with its stars. Conclusions: We have discovered that two knots along NGC 1097's northeast tidal stream share most of their spectral and photometric properties with ordinary dwarf spheroidal galaxies (dSph). Moreover, we find strong indications that the “dog-leg” tidal stream arises from the tidal disruption of knot A. Since it has been demonstrated that tidally stripping dSph galaxies need to loose most of their dark matter before starting to loose stars

  10. Net sediment transport in tidal basins: quantifying the tidal barotropic mechanisms in a unified framework (United States)

    Gatto, Vincenzo Marco; van Prooijen, Bram Christiaan; Wang, Zheng Bing


    Net sediment transport in tidal basins is a subtle imbalance between large fluxes produced by the flood/ebb alternation. The imbalance arises from several mechanisms of suspended transport. Lag effects and tidal asymmetries are regarded as dominant, but defined in different frames of reference (Lagrangian and Eulerian, respectively). A quantitative ranking of their effectiveness is therefore missing. Furthermore, although wind waves are recognized as crucial for tidal flats' morphodynamics, a systematic analysis of the interaction with tidal mechanisms has not been carried out so far. We review the tide-induced barotropic mechanisms and discuss the shortcomings of their current classification for numerical process-based models. Hence, we conceive a unified Eulerian framework accounting for wave-induced resuspension. A new methodology is proposed to decompose the sediment fluxes accordingly, which is applicable without needing (semi-) analytical approximations. The approach is tested with a one-dimensional model of the Vlie basin, Wadden Sea (The Netherlands). Results show that lag-driven transport is dominant for the finer fractions (silt and mud). In absence of waves, net sediment fluxes are landward and spatial (advective) lag effects are dominant. In presence of waves, sediment can be exported from the tidal flats and temporal (local) lag effects are dominant. Conversely, sand transport is dominated by the asymmetry of peak ebb/flood velocities. We show that the direction of lag-driven transport can be estimated by the gradient of hydrodynamic energy. In agreement with previous studies, our results support the conceptualization of tidal flats' equilibrium as a simplified balance between tidal mechanisms and wave resuspension.

  11. Power Generation for River and Tidal Generators

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wright, Alan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Donegan, James [Ocean Renewable Power Company (ORPC), Portland, ME (United States); Marnagh, Cian [Ocean Renewable Power Company (ORPC), Portland, ME (United States); McEntee, Jarlath [Ocean Renewable Power Company (ORPC), Portland, ME (United States)


    Renewable energy sources are the second largest contributor to global electricity production, after fossil fuels. The integration of renewable energy continued to grow in 2014 against a backdrop of increasing global energy consumption and a dramatic decline in oil prices during the second half of the year. As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded from primarily wind and solar to include new types with promising future applications, such as hydropower generation, including river and tidal generation. Today, hydropower is considered one of the most important renewable energy sources. In river and tidal generation, the input resource flow is slower but also steadier than it is in wind or solar generation, yet the level of water turbulent flow may vary from one place to another. This report focuses on hydrokinetic power conversion.

  12. Tidal reorientation and the fracturing of Jupiter's moon Europa (United States)

    McEwen, A.S.


    The most striking characteristic of Europa is the network of long linear albedo markings over the surface, suggestive of global-scale tectonic processes. Various explanations for the fractures have been proposed: Freezing and expansion of an early liquid water ocean1, planetary expansion due to dehydration of hydrated silicates2, localization by weak points in the crust generated by impacts3, and a combination of stresses due to planetary volume change and tidal distortions from orbital recession and orbital eccentricity4,5. Calculations by Yoder6 and Greenberg and Weidenschilling7 have shown that Europa may rotate slightly more rapidly than the synchronous rate, with a rotation period (reorientation through 360??) ranging from 20 to >103 yr if a liquid mantle is present, or up to 1010 yr if the satellite is essentially solid7. Helfen-stein and Parmentier8 modelled the stresses due to nonsynchronous rotation, and concluded that this could explain the long fractures in part of the anti-jovian hemisphere. In this note, I present a global map of lineaments with long arc lengths (>20?? or 550 km), and compare the lineament orientations to the tensile stress trajectories due to tidal distortions (changes in the lengths of three principal semiaxes) and to nonsynchronous rotation (longitudinal reorientation of two of the principal semiaxes). An excellent orthogonal fit to the lineaments is achieved by the stresses due to nonsynchronous rotation with the axis radial to Jupiter located 25?? east of its present position. This fit suggests that nonsynchronous rotation occurred at some time in Europa's history. ?? 1986 Nature Publishing Group.

  13. Stratification on the Skagit Bay Tidal Flats (United States)


    shore Skagit Bay a Camano Island -1 0 1 -2-1012 0.5 -0.5 1 -1 C ro ss -s ho re (k m ) Alongshore (km) 0 b 1 0 -1 Bed level (m ) 18 2.2 Modeled...shadowed by Camano Island, which forms the southern border of the tidal flats (Fig. 2-3c). Saline water has propagated onshore and a roughly

  14. Integrating tidal and nontidal ecological assessments (United States)

    Mark Southerland; Roberto Llanso


    The Maryland Department of Natural Resources (DNR) has a long history of conducting rigorous assessments of ecological conditions in both tidal and nontidal waters. The Long-Term Benthic (LTB) Monitoring Program and the Maryland Biological Stream Survey (MBSS) both use reference-based indicators of benthic invertebrate communities to provide areawide estimates of ...

  15. Tidally driven evolution of differentiated terrestrial exoplanets (United States)

    Walterova, M.; Behounkova, M.


    We present a numerical model of tidally driven orbital evolution based on the solution of continuum mechanics equations for a differentiated spherical body, whose mantle is governed by either the Maxwell or the Andrade viscoelastic rheology. The model enables generally heterogeneous structure of the mantle, making thus possible the analysis of coupling between the internal and the orbital evolution of terrestrial exoplanets or icy moons.


    Energy Technology Data Exchange (ETDEWEB)

    Dong Subo; Katz, Boaz; Socrates, Aristotle [Institute for Advanced Study, Princeton, NJ 08540 (United States)


    Upcoming direct-imaging experiments may detect a new class of long-period, highly luminous, tidally powered extrasolar gas giants. Even though they are hosted by {approx} Gyr-'old' main-sequence stars, they can be as 'hot' as young Jupiters at {approx}100 Myr, the prime targets of direct-imaging surveys. They are on years-long orbits and presently migrating to 'feed' the 'hot Jupiters'. They are expected from 'high-e' migration mechanisms, in which Jupiters are excited to highly eccentric orbits and then shrink semimajor axis by a factor of {approx}10-100 due to tidal dissipation at close periastron passages. The dissipated orbital energy is converted to heat, and if it is deposited deep enough into the atmosphere, the planet likely radiates steadily at luminosity L {approx} 100-1000 L{sub Jup}(2 Multiplication-Sign 10{sup -7}-2 Multiplication-Sign 10{sup -6} L{sub Sun }) during a typical {approx} Gyr migration timescale. Their large orbital separations and expected high planet-to-star flux ratios in IR make them potentially accessible to high-contrast imaging instruments on 10 m class telescopes. {approx}10 such planets are expected to exist around FGK dwarfs within {approx}50 pc. Long-period radial velocity planets are viable candidates, and the highly eccentric planet HD 20782b at maximum angular separation {approx}0.''08 is a promising candidate. Directly imaging these tidally powered Jupiters would enable a direct test of high-e migration mechanisms. Once detected, the luminosity would provide a direct measurement of the migration rate, and together with mass (and possibly radius) estimate, they would serve as a laboratory to study planetary spectral formation and tidal physics.

  17. Methods for monitoring tidal flushing in large animal burrows in tropical mangrove swamps (United States)

    Hollins, Suzanne E.; Heron, Scott F.; Ridd, Peter V.


    The typically anaerobic nature of mangrove sediments provides significant challenges to the mangrove trees and biota inhabiting them. The burrowing activities and flow of water through the numerous and complex animal burrows perforating the sediments of mangroves have a major influence on the biogeochemistry of the sediments and are important to the enhancement of nutrient and oxygen exchange. Two new methods are presented for monitoring the tidal flushing of Sesarma messa and Alpheus cf macklay burrows in a Rhizophora stylosa mangrove forest - by measuring oxygen content of burrow water and by determining the change in fluorescence of a dye tracer through tidal inundation. A case study using the first of these showed oxygen consumption rates at the burrow wall deep within the burrow were found to be between 210 and 460 μmol O 2 m -2 h -1. The influx of oxygen during a flood tide was found to be significant and indicated that approximately 40% of the burrow water is flushed during a single tidal event. However, the high consumption rate of oxygen within the burrow resulted in the oxygen concentration remaining at or below one-third of the oxygen content of the flooding tidal water. A test application of the second method, using rhodamine dye as a tracer, indicated that the exchange of water between the burrow and the flooding tide was found to be in the order of 30% of the burrow volume. These new techniques provide a means to further study the nutrient exchange within these burrow systems and verify the initial findings that several tidal inundations are necessary to completely flush the burrows.

  18. End tidal carbon dioxide levels during the resuscitation of prematurely born infants. (United States)

    Murthy, Vadivelam; O'Rourke-Potocki, Anthony; Dattani, Nikesh; Fox, Grenville F; Campbell, Morag E; Milner, Anthony D; Greenough, Anne


    Successful resuscitation of prematurely born infants is dependent on achieving adequate alveolar ventilation and vasodilation of the pulmonary vascular bed. Elevation of end-tidal carbon dioxide (ETCO(2)) levels may indicate pulmonary vasodilation. This research aims to study the temporal changes in ETCO(2) levels and the infant's respiratory efforts during face mask resuscitation in the labour suite, and to determine if the infant's first inspiratory effort was associated with a rise in the ETCO(2) levels, suggesting pulmonary vasodilation had occurred. This study is an observational one. The subjects of the study are forty infants with a median gestational age of 30 weeks (range 23-34). Inflation pressures, expiratory tidal volumes and ETCO(2) levels were measured. The median expiratory tidal volume of inflations prior to the onset of the infant's respiratory efforts (passive inflations) was lower than that of the inflation associated with the first inspiratory effort (active inflation) (1.8 (range 0.1-7.3) versus 6.3 ml/kg (range 1.9-18.4), pmask resuscitation, improved carbon dioxide elimination, likely due to pulmonary vasodilation, occurred with the onset of the infant's respiratory efforts. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Super-Eddington Accreting Tidal Disruption Events (United States)

    Lin, Dacheng; Guillochon, James; Komossa, St.; Ramirez-Ruiz, Enrico; Irwin, Jimmy; Maksym, W. Peter; Grupe, Dirk; Godet, Olivier; Webb, Natalie; Barret, Didier; Zauderer, Bevin; Duc, Pierre-Alain; Carrasco, Eleazar R.; Gwyn, Stephen


    Multiwavelength flares from tidal disruption and subsequent accretion of stars are important for study of otherwise dormant massive black holes in galactic nuclei. Previous well-monitored candidate flares were short-lived, with most emission confined to within ~1 year. Here, we report our discovery of a well observed super-long (>11 years) luminous X-ray flare from the nuclear region of a dwarf starburst galaxy. After an apparently fast rise within ~4 months a decade ago, the X-ray luminosity, though showing a weak trend of decay, has been persistently high at around the Eddington limit. The X-ray spectra are soft and can be described with Comptonized emission from an optically thick low-temperature corona, a super-Eddington accretion signature often observed in accreting stellar-mass black holes. Dramatic spectral softening was also caught in one recent observation, implying either a temporary transition from the super-Eddington accretion state to the standard thermal state, or the presence of a transient highly blueshifted (~0.36c) warm absorber. All these properties in concert suggest a tidal disruption event with an unusually long super-Eddington accretion phase that has never before been observed. We also found two additional events showing similar X-ray spectra characteristic of super-Eddington accretion from two otherwise quiescent galaxies. Therefore these events seem to form a new, super-Eddington accreting class of tidal disruption events.

  20. Tidal controls on river delta morphology (United States)

    Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.


    River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

  1. Tidal energy extraction: renewable, sustainable and predictable. (United States)

    Nicholls-Lee, R F; Turnock, S R


    The tidal flow of sea water induced by planetary motion is a potential source of energy if suitable systems can be designed and operated in a cost-effective manner This paper examines the physical origins of the tides and how the local currents are influenced by the depth of the seabed and presence of land mass and associated coastal features. The available methods of extracting energy from tidal movement are classified into devices that store and release potential energy and those that capture kinetic energy directly. A survey is made of candidate designs and, for the most promising, the likely efficiency of energy conversion and methods of installing them are considered. Overall, the need to reduce CO2 emissions, a likely continued rise in fossil fuel cost will result in a significantly increased use of tidal energy. What is still required, especially for kinetic energy devices, is a much greater understanding of how they can be designed to withstand long-term immersion in the marine environment.

  2. Numerical Simulations of the Effects of a Tidal Turbine Array on Near-Bed Velocity and Local Bed Shear Stress

    Directory of Open Access Journals (Sweden)

    Philip A. Gillibrand


    Full Text Available We apply a three-dimensional hydrodynamic model to consider the potential effects of energy extraction by an array of tidal turbines on the ambient near-bed velocity field and local bed shear stress in a coastal channel with strong tidal currents. Local bed shear stress plays a key role in local sediment dynamics. The model solves the Reynold-averaged Navier-Stokes (RANS equations on an unstructured mesh using mixed finite element and finite volume techniques. Tidal turbines are represented through an additional form drag in the momentum balance equation, with the thrust imparted and power generated by the turbines being velocity dependent with appropriate cut-in and cut-out velocities. Arrays of 1, 4 and 57 tidal turbines, each of 1.5 MW capacity, were simulated. Effects due to a single turbine and an array of four turbines were negligible. The main effect of the array of 57 turbines was to cause a shift in position of the jet through the tidal channel, as the flow was diverted around the tidal array. The net effect of this shift was to increase near-bed velocities and bed shear stress along the northern perimeter of the array by up to 0.8 m·s−1 and 5 Pa respectively. Within the array and directly downstream, near-bed velocities and bed shear stress were reduced by similar amounts. Changes of this magnitude have the potential to modify the known sand and shell banks in the region. Continued monitoring of the sediment distributions in the region will provide a valuable dataset on the impacts of tidal energy extraction on local sediment dynamics. Finally, the mean power generated per turbine is shown to decrease as the turbine array increased in size.

  3. Effects of increasing seawater circulation by tidal power plant operation on the water quality in the Shihwa coastal reservoir, Republic of Korea (United States)

    Lee, B. Y.; Lee, C. H.; KIm, K. T.


    Since 2012 to present, the Tidal Power Plant (TPP) has been operated in Shihwa Coastal Reservoir (SCR) to improve the water quality. The tidal mixing volume increased about 5 times from 0.03 to 0.16 billion ton/day which represents about 50% of the SCR water volume. Water quality monitoring data showed that it break a strong stratification and hypoxia (≤3 mg/L Dissolved Oxygen) during summer season in main tidal channel. In addition, Total Phosphorus (TP), Total Nitrogen (TN) and Chemical Oxygen Demand concentrations in the main tidal channel reached to similar level with outside SCR concentrations. However, inner area with limited tidal mixing has not experienced improvement in TN and TP concentrations after the TPP operation. Trophic State Index (TSI) which was composite index of trophic condition also kept high score (>50) and remained in eutrophic state especially in summer season. Overall, an increase of seawater circulation has a positive effect on water quality in main tidal channel but not in inner area because of limited seawater mixing and effects of stormwater runoff. The stormwater runoff should be properly managed in this case because most point source pollution load is discharged outside of SCR. Acknowledgement : This research was a part of the project titled 'Development of integrated estuarine management system', funded by the Ministry of Oceans and Fisheries, Korea

  4. Ergonomia ambiental em veículos


    Alcobia, Carlos José de Oliveira Pereira e Jorge


    Tese de doutoramento em Ciências de Engenharia Mecânica (Aerodinâmica) apresentada à Fac. de Ciências e Tecnologia de Coimbra As condições ambientais no interior dos veículos representam, hoje em dia, uma área de investigação e desenvolvimento preferencial por parte de muitos fabricantes. Face ao incremento da análise entre o ser humano e os diversos estímulos ambientais que influenciam o conforto no interior dos veículos, surge a necessidade de desenvolver metodologias que permitam mod...

  5. Kokkeuddannelse for døve

    DEFF Research Database (Denmark)

    Hansen, Niels-Henrik Møller; Wittendorff, Nina

    I denne rapport præsenterer vi en evaluering af projektet "Nye veje for unge døve, døvblinde og hørehæmmede i Danmark". Hensigten med dette projekt er at kunne tilbyde døve, døvblinde og hørehæmmede personer et uddannelsestilbud inden for fremstilling af mad. Konkret handler det bl.a. om en kokke......- og catering-uddannelse rettet mod personer med hørevanskeligheder....

  6. Using VE to Strategically Plan Our Future

    Energy Technology Data Exchange (ETDEWEB)

    Margie Jeffs; Lori Braase; Alison Conner; Darcie Martinson; Jodi Grgich


    The Value Engineering (VE) Methodology is an effective tool for business or project strategic planning. In conjunction with the “Balanced Scorecard Approach” (Drs. Robert Kaplan, PhD, and David Norton, PhD, from the Balanced Scorecard Collaborative/Palladium Group), function analysis can be used to develop strategy maps and scorecards. The FAST diagram provides an integrated approach to strategy map development by formulating a cause and effect relationship and establishing the “how” and “why” behind the strategy map. By utilizing the VE Job Plan, one is able to move from strategic thinking all the way through to execution of the strategy.

  7. Tidal Tales of Minor Mergers: Star Formation in the Tidal Tails of Minor Mergers (United States)

    Knierman, Karen; Monkiewicz, Jacqueline; Scowen, Paul; Groppi, Christopher


    While major mergers and their tidal debris are well studied, equal mass galaxy mergers are relatively rare compared to minor mergers (mass ratio tails in minor mergers can range over orders of magnitude on both local and global scales, and include several star forming regions with higher than normal SFE. From the tidal debris environments in our study, this variance appears to stem from the formation conditions of the debris. New results from the first survey of molecular hydrogen in minor merger tidal debris will be presented. Current surveys of the 2.12 micron line of molecular hydrogen, CO(1-0), and HI for 15 minor mergers, are providing a larger sample of environments to study the threshold for star formation that can inform star formation models, particularly at low densities.

  8. Time and volume dependence of dead space in healthy and surfactant-depleted rat lungs during spontaneous breathing and mechanical ventilation. (United States)

    Dassow, Constanze; Schwenninger, David; Runck, Hanna; Guttmann, Josef


    Volumetric capnography is a standard method to determine pulmonary dead space. Hereby, measured carbon dioxide (CO2) in exhaled gas volume is analyzed using the single-breath diagram for CO2. Unfortunately, most existing CO2 sensors do not work with the low tidal volumes found in small animals. Therefore, in this study, we developed a new mainstream capnograph designed for the utilization in small animals like rats. The sensor was used for determination of dead space volume in healthy and surfactant-depleted rats (n = 62) during spontaneous breathing (SB) and mechanical ventilation (MV) at three different tidal volumes: 5, 8, and 11 ml/kg. Absolute dead space and wasted ventilation (dead space volume in relation to tidal volume) were determined over a period of 1 h. Dead space increase and reversibility of the increase was investigated during MV with different tidal volumes and during SB. During SB, the dead space volume was 0.21 ± 0.14 ml and increased significantly at MV to 0.39 ± 0.03 ml at a tidal volume of 5 ml/kg and to 0.6 ± 0.08 ml at a tidal volume of 8 and 11 ml/kg. Dead space and wasted ventilation during MV increased with tidal volume. This increase was mostly reversible by switching back to SB. Surfactant depletion had no further influence on the dead space increase during MV, but impaired the reversibility of the dead space increase.

  9. Geometric properties of hydraulic-relevant tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Ferret, Yann; Lefebvre, Alice


    Large compound tidal bedforms (also termed dunes, sandwaves, megaripples by different authors) constitute prominent roughness elements in tidal channels and estuaries. Quantitative knowledge on their geometry, dynamics and hydraulic effect is crucial for coastal system understanding and process...... to technical constraints and data reduction the (historic) data bases mostly are restricted to information on mean geometrical states, whereas individual bedform properties are often not reported. Recently Lefebvre et al. (2011) showed that the hydraulic effect of asymmetric compound tidal bedforms depends...... on the tidal stage: Whereas the secondary bedforms act as roughness elements throughout the tidal cycle, the large primary bedforms dominate the hydraulics when the tidal flow is in the (dominant) direction of the bedform orientation (e.g. ebb-directed primary bedforms act during ebb currents) when...

  10. Tidal bending of glaciers: a linear viscoelastic approach

    DEFF Research Database (Denmark)

    Reeh, Niels; Christensen, Erik Lintz; Mayer, Christoph


    In theoretical treatments of tidal bending of floating glaciers, the glacier is usually modelled as an elastic beam with uniform thickness, resting on an elastic foundation. With a few exceptions, values of the elastic (Young's) modulus E of ice derived from tidal deflection records of floating....... This suggests that ice creep may have a significant influence on tidal bending of glaciers. Moreover, detailed tidal-deflection and tilt data from Nioghalvfjerdsfjorden glacier, northeast Greenland, cannot be explained by elastic-beam theory. We present a theory of tidal bending of glaciers based on linear...... glaciers are in the range 0.9-3 GPa. It has therefore been suggested that the elastic-beam model with a single value of E approximate to 1 GPa adequately describes tidal bending of glaciers.In contrast, laboratory experiments with ice give E =93 GPa, i.e. 3-10 times higher than the glacier-derived values...

  11. How Cassini can constrain tidal dissipation in Saturn (United States)

    Luan, Jing; Fuller, Jim; Quataert, Eliot


    Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parametrized equilibrium tidal theory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Resonance locking between satellites and internal oscillations of Saturn naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn's gravitational field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini's proximal orbits if migration of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

  12. Bathymetric Control of Front Generation in a Tidal River (United States)


    important linkages between the land margin and the coastal ocean serving as major export pathways for terrigenous sediment (Childers and Day, 1990a... sediment dynamics (Largier, 1993). Tidal creeks are small costal inlets or else side channels or tributaries of tidal rivers, the flow in which is...relative strengths of the tidal flows and the river flows. As the river water picks up much sediment in the shallow side creek, the action of the shoals

  13. Progress in developing tidal electric power plants reported (United States)

    Blokhnin, A.


    The natural energy potential of tides on the shores of the U.S.S.R. is equal to about a third of the world's total. The Achilles heel of tidal power plants is their pulsating operation. One solution to this problem was to build a hydroelectric power plant for use in tandem with the tidal power plant. During lulls in the tidal plant, the hydraulic power plant switches on at full power. Possible sites for dual plants were discussed.

  14. A two-step non-flowcytometry-based naïve B cell isolation method and its application in Staphylococcal enterotoxin B (SEB) presentation. (United States)

    Chokeshai-u-saha, Kaj; Buranapraditkun, Supranee; Jacquet, Alain; Nguyen, Catherine; Ruxrungtham, Kiat


    To study the role of human naïve B cells in antigen presentation and stimulation to naïve CD4+ T cell, a suitable method to reproducibly isolate sufficient naïve B cells is required. To improve the purity of isolated naive B cells obtained from a conventional one-step magnetic bead method, we added a rosetting step to enrich total B cell isolates from human whole blood samples prior to negative cell sorting by magnetic beads. The acquired naïve B cells were analyzed for phenotypes and for their role in Staphylococcal enterotoxin B (SEB) presentation to naïve CD4+ T cells. The mean (SD) naïve B cell (CD19+/CD27-) purity obtained from this two-step method compared with the one-step method was 97% (1.0) versus 90% (1.2), respectively. This two-step method can be used with a sample of whole blood as small as 10 ml. The isolated naive B cells were phenotypically at a resting state and were able to prime naïve CD4+ T cell activation by Staphylococcal enterotoxin B (SEB) presentation. This two-step non-flow cytometry-based approach improved the purity of isolated naïve B cells compared with conventional one-step magnetic bead method. It also worked well with a small blood volume. In addition, this study showed that the isolated naïve B cells can present a super-antigen "SEB" to activate naïve CD4 cells. These methods may thus be useful for further in vitro characterization of human naïve B cells and their roles as antigen presenting cells in various diseases.

  15. How does a tidal embayment morphodynamically react on sea level rise? (United States)

    van der Wegen, Mick


    Conditions for (assumed) equilibrium in tidal embayments have been studied extensively in the past years with morphodynamic 1D models (Van Dongeren and De Vriend, 1994; Schuttelaars and de Swart, 1996, 2000; Lanzoni and Seminara, 2002) and 2D models (Hibma et al. [2003], Van der Wegen and Roelvink [2008]) Van der Wegen et al 2008). The current research addresses the impact of sea level rise on tidal embayments. Although effects of sea level rise may only become apparent after decades, the character of the embayment can change considerably. Examples are the (dis)appearance or re-allocation of intertidal flats, increased tidal resonance, shift from sediment export to import, deepening of channel area and other related (ecological) parameters. The research applies a 2D morphodynamic model (Delft3D) in an idealized environment. The model is based on the 2 D shallow water equations, the Engelund -Hansen transport formula and includes bed slope effects, drying and flooding procedures and an advanced morphodynamic update scheme (Roelvink 2006). The initial condition of the bathymetry is generated by 3000 years of morphodynamic calculations in a 80 km long and 2.5 km wide rectangular tidal embayment under constant M2 tidal forcing conditions (Van der Wegen and Roelvink [2008]). After this period sea level rise gradually developing towards a rate of 0.4 m/century is added to the boundary conditions. Model results describe development towards less intertidal area and a transition from an exporting system to a importing system. Model results are evaluated in terms of M2, M4 and M6 tidal constituents as well as against Vs/Vc (shoal volume over channel volume) versus a/h (amplitude over water depth) relationship as proposed by Friedrichs and Aubrey (1988). Although the model describes morphodynamic development in a strongly idealized environment the results can provide an excellent tool to systematically study the impact of sea level rise in tidal embayments as well as the time

  16. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler


    Full Text Available Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi, Chemical Abstracts Service , EBSCO Discovery Service, Google Scholar, WorldCat ve Zentralblatt MATH indekslerinde taranmaktadır.Süleyman Demirel University Journal of Natural and Applied Sciences is indexed in Chemical Abstracts Service, EBSCO Discovery Service, Google Scholar, WorldCat and Zentralblatt MATH.

  17. New estimates of oceanic tidal energy dissipation from satellite altimetry (United States)

    Cartwright, David E.; Ray, Richard D.


    As a novel approach to computing the flux of tidal power into shelf areas, tidal maps of an oceanic area near the Patagonian Shelf are derived from 11 months of altimetry records from the GEOSAT satellite. Power fluxes are computed from the maps through Laplace's tidal equations. Flux vectors for M2 clearly show a convergence on to the southern portion of the shelf sea and their total is nearly twice the loss computed by Miller for that area. A decrease of 'quality factor' with frequency from M2 to S2 is in keeping with Webb's hypothesis of shelf resonances at frequencies a little higher than the tidal band.

  18. On tidal migration in the shrimp Crangon crangon (United States)

    Janssen, G. M.; Kuipers, B. R.

    The length-frequency distribution of the shrimp population in the tidal flat area Balgzand in the western Wadden Sea shows a spatial separation between the adult shrimps, that inhibit the subtidal, and the juveniles (< 2.5 cm) that are restricted to the tidal zone. Observations in the tidal channel through the tides indicate that the juvenile population does not show migration of any importance from the tidal zone during ebb. Samples on the emerged flats during LW proof the presence of these juveniles in about the same densities as observed during HW.

  19. Turbulent viscosity and Jupiter's tidal Q. [energy dissipation function (United States)

    Goldreich, P.; Nicholson, P. D.


    A recent estimate of tidal dissipation by turbulent viscosity in Jupiter's convective interior predicts that the current value of the planet's tidal Q is roughly 5 million. We point out a fundamental error in this calculation, and show that turbulent dissipation alone implies that at present Q is about 50 trillion. Our reduced estimate for the rate of tidal dissipation shows conclusively that tidal torques have produced only negligible modifications of the orbits of the Galilean satellites over the age of the solar system.

  20. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing (United States)

    Jahani, Nariman; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A.


    This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R2 ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs. PMID:26316512

  1. Waddenfonds Tidal Texel Demonstration project. BlueTEC Texel Tidal Project: Environmental measurement and performance analysis

    NARCIS (Netherlands)

    Ponsoni, L.; Nauw, J.J.; Smit, M.; Ober, S.; Nichols, C.; Kenkhuis, J.; Schmidt, C.; Buatois, A.; de Haas, P.


    In the context of the BlueTEC project, this report starts by introducing theBlueTEC tidal energy platform and reviewing the patterns of circulation of theMarsdiep inlet. The energy resource assessment and the site selection for theplatform's deployment are reported. This document analyses di?erent

  2. Stellar binaries in galactic nuclei: tidally stimulated mergers followed by tidal disruptions (United States)

    Bradnick, B.; Mandel, I.; Levin, Y.


    We investigate interactions of stellar binaries in galactic nuclear clusters with a massive black hole (MBH). We consider binaries on highly eccentric orbits around the MBH that change due to random gravitational interactions with other stars in the nuclear stellar cluster. The pericentres of the orbits perform a random walk, and we consider cases where this random walk slowly brings the binary to the Hills tidal separation radius (the so-called empty loss-cone regime). However, we find that in a majority of cases, the expected separation does not occur and instead the members of the binary merge together. This happens because the binary's eccentricity is excited by tidal interactions with the MBH, and the relative excursions of the internal eccentricity of the binary far exceed those in its internal semimajor axis. This frequently reduces the pericentre separation to values below typical stellar diameters, which induces a significant fraction of such binaries to merge (≳75 per cent in our set of numerical experiments). Stellar tides do not appreciably change the total rate of mergers but circularize binaries, leading to a significant fraction of low-eccentricity, low-impact-velocity mergers. Some of the stellar merger products will then be tidally disrupted by the MBH within ∼106 yr. If the merger strongly enhances the magnetic field of the merger product, this process could explain observations of prompt relativistic jet formation in some tidal disruption events.

  3. Atmospheric dynamics of tidally synchronized extrasolar planets. (United States)

    Cho, James Y-K


    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  4. Tidal Dynamics and Mixing Over Steep Topography (United States)


    of tidal vorticity is the mechanism by which residual vorticity is generated. Also by running simplified numerical solutions in a Eulerian sense...In the case of Monterey Bay, depths range from 1O00m to lOOm over distances of 5000m , corresponding to very large slopes of approximately 15% and 100...experiment were UT=O.Oss/s, dh/dxuO.1S (slope) with depths ranging from h(O)=1OOm to hb=lOOOu over a 5000m horizontal distance across the slope. Figure

  5. Interactions Between Wetlands and Tidal Inlets (United States)


    and γ = 2). Depth is relative to mean sea level, and square cells represent inactive regions. 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 A’ h’ — r...represent a vegetation density of 320 stems/m2 and square cells represent inactive regions. where αc is a correction factor for the presence of a tidal...velocities at four observation stations are shown in Figure 5 for the idealized estuaries with shape factors equal to 2 and 5, which represent vege

  6. A new relativistic model for tidal stream evolution during tidal disruption events (United States)

    Servin, Juan; Kesden, Michael


    When stars are tidally disrupted by a supermassive black hole, approximately half of their original mass becomes gravitationally bound and may eventually produce a tidal flare. The stellar debris evolves into streams that can self-intersect due to relativistic pericenter precession. Energy loss in these inelastic collisions both circularizes the stream and contributes to the tidal flare. Models of this process often assume that all elements of the tidal stream have the same specific energy and angular momentum as the most bound debris element. Real tidal debris possesses a distribution of binding energies, however, which grants it a distribution of orbits. We propose a new treatment for this debris, wherein we evolve the elements of the stream individually. We determine the radial distance (from the black hole) and the time (after the disruption) of the stream collisions as a function of black-hole mass under both Newtonian gravity (N+1PN) and general relativity (GR). We also use the Lane-Emden equation to account for the mass differences among the debris elements when calculating the energy loss in the inelastic collisions. For the N+1PN method, we evolve the stream using Newtonian orbital mechanics and apply pericenter precession after each pericenter passage using a first-order post-Newtonian approximation. Our relativistic method directly integrates the geodesic equations of motion. We see that the higher precession in the fully relativistic method results in more prompt collisions, and that assuming equal masses for the colliding debris elements greatly overestimates the energy loss resulting from these collisions. We also provide light curves for the corresponding flares and compare our predictions to those of previous models.

  7. The origin of neap-spring tidal cycles (United States)

    Kvale, E.P.


    The origin of oceanic tides is a basic concept taught in most introductory college-level sedimentology/geology, oceanography, and astronomy courses. Tides are typically explained in the context of the equilibrium tidal theory model. Yet this model does not take into account real tides in many parts of the world. Not only does the equilibrium tidal model fail to explicate amphidromic circulation, it also does not explain diurnal tides in low latitude positions. It likewise fails to explain the existence of tide-dominated areas where neap-spring cycles are synchronized with the 27.32-day orbital cycle of the Moon (tropical month), rather than with the more familiar 29.52-day cycle of lunar phases (synodic month). Both types of neap-spring cycles can be recognized in the rock record. A complete explanation of the origin of tides should include a discussion of dynamic tidal theory. In the dynamic tidal model, tides resulting from the motions of the Moon in its orbit around the Earth and the Earth in its orbit around the Sun are modeled as products of the combined effects of a series of phantom satellites. The movement of each of these satellites, relative to the Earth's equator, creates its own tidal wave that moves around an amphidromic point. Each of these waves is referred to as a tidal constituent. The geometries of the ocean basins determine which of these constituents are amplified. Thus, the tide-raising potential for any locality on Earth can be conceptualized as the result of a series of tidal constituents specific to that region. A better understanding of tidal cycles opens up remarkable opportunities for research on tidal deposits with implications for, among other things, a more complete understanding of the tidal dynamics responsible for sediment transport and deposition, changes in Earth-Moon distance through time, and the possible influences tidal cycles may exert on organisms. ?? 2006 Elsevier B.V. All rights reserved.

  8. Recognition of Tidal Bore Deposits in the Stratigraphic Record (United States)

    Fielding, C. R.; Joeckel, M.


    Tidal bores are upstream-propagating hydraulic jumps that episodically form the leading edge of flood tides in upstream-narrowing, gently sloping, coastal rivers which experience high tidal ranges (6 m+, typically). They attain 9 m in height and can penetrate more than 100 km inboard of a shoreline. The deposits of tidal bores, if they can be confidently diagnosed in ancient successions, constitute an unequivocal line of evidence in support of deposition within the tidal-fluvial zone of a lowland river. Deposits of modern tidal bores have been documented, and two recent studies have interpreted tidal bore deposits in ancient (Jurassic and Pennsylvanian) sedimentary rocks. The ancient tidal bore deposits recognized thus far comprise laterally discontinuous, erosionally-based beds of massive to faintly stratified sand, locally muddy and rich in detrital plant debris. Paleoflow structures, where preserved, indicate upstream-directed flow. The beds are enclosed by other, more pervasively stratified sandstones that were the product of ebb and flood-oriented currents in the ancient tidal rivers. The interpreted bore deposits are anomalous in the context of these normal current deposits, and indicate erosive scouring of the substrate followed by the en masse deposition of sand from suspension and upstream advection. Multiple horizons of putative tidal bore deposits are recognized in both the Jurassic and Pennsylvanian examples, suggesting that they were not the product of low-frequency, high-magnitude events such as tsunami or debris flows. It is anticipated that more examples of ancient tidal bore deposits will come to light now that diagnostic criteria are available, and that these will contribute to the fuller recognition of tidally-modulated fluvial deposits in the rock record.

  9. Tidal instability in exoplanetary systems evolution

    Directory of Open Access Journals (Sweden)

    Le Gal P.


    Full Text Available A new element is proposed to play a role in the evolution of extrasolar planetary systems: the tidal (or elliptical instability. It comes from a parametric resonance and takes place in any rotating fluid whose streamlines are (even slightly elliptically deformed. Based on theoretical, experimental and numerical works, we estimate the growth rate of the instability for hot-jupiter systems, when the rotation period of the star is known. We present the physical process, its application to stars, and preliminary results obtained on a few dozen systems, summarized in the form of a stability diagram. Most of the systems are trapped in the so-called "forbidden zone", where the instability cannot grow. In some systems, the tidal instability is able to grow, at short timescales compared to the system evolution. Implications are discussed in the framework of misaligned transiting systems, as the rotational axis of the star would be unstable in systems where this elliptical instability grows.

  10. Study of a Tidal Disruption Event Candidate (United States)

    Hampel, J.; Reiprich, T.; Freyberg, M.; Greiner, J.; Komossa, S.


    During the close encounter of a star with a supermassive black hole, the star might get disrupted by the black hole's tidal forces (tidal disruption events, TDE). The accretion of the stellar material onto the black hole creates luminous emission at different wavelength, including X-rays. We will report the results of an investigation of a bright X-ray source in a set of five ROSAT PSPC observations. The light curve of this event shows an increase in brightness by a factor of nine within eight days, followed by a strong fading over the following 165 days. This observation seems inconsistent with common X-ray source variability, such as active galactic nuclei, and more in favor of a TDE. In order to investigate the possible TDE origin, optical and X-ray spectra have been analyzed. An expected absence of emission lines in the optical and a very soft X-ray spectrum are confirmed. Detailed comparisons with known TDEs show discrepancies in the light curves. Particularly, the increase in brightness happens over a shorter timescale than comparable events. The study of this TDE candidate might help to gain a better understanding of such events, especially for the expected TDE discoveries with the upcoming eROSITA all-sky survey.

  11. Tidal Dwarf Galaxies and Missing Baryons

    Directory of Open Access Journals (Sweden)

    Frederic Bournaud


    Full Text Available Tidal dwarf galaxies form during the interaction, collision, or merger of massive spiral galaxies. They can resemble “normal” dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the “missing baryons,” known to exist but not directly observed. The number of dwarf galaxies in the Universe is another cosmological problem for which it is important to ascertain if tidal dwarf galaxies formed frequently at high redshift, when the merger rate was high, and many of them survived until today. In this paper, “dark matter” is used to refer to the nonbaryonic matter, mostly located in large dark halos, that is, CDM in the standard paradigm, and “missing baryons” or “dark baryons” is used to refer to the baryons known to exist but hardly observed at redshift zero, and are a baryonic dark component that is additional to “dark matter”.

  12. Shape Design of the Duct for Tidal Converters Using Both Numerical and Experimental Approaches (pre-2015

    Directory of Open Access Journals (Sweden)

    Chul H. Jo


    Full Text Available Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Among the various ocean energy sources, tidal current power (TCP is recognized as the most promising energy source in terms of predictability and reliability. The enormous energy potential in TCP fields has been exploited by installing TCP systems. The flow velocity is the most important factor for power estimation of a tidal current power system. The kinetic energy of the flow is proportional to the cube of the flow’s velocity, and velocity is a critical variable in the performance of the system. Since the duct can accelerate the flow velocity, its use could expand the applicable areas of tidal devices to relatively low velocity sites. The inclined angle of the duct and the shapes of inlet and outlet affect the acceleration rates of the flow inside the duct. In addition, the volume of the duct can affect the flow velocity amplification performance. To investigate the effects of parameters that increase the flow velocity, a series of simulations are performed using the commercial computational fluid dynamics (CFD code ANSYS-CFX. Experimental investigations were conducted using a circulation water channel (CWC.

  13. Physiological techniques for detecting expiratory flow limitation during tidal breathing

    Directory of Open Access Journals (Sweden)

    N.G. Koulouris


    Full Text Available Patients with severe chronic obstructive pulmonary disease (COPD often exhale along the same flow–volume curve during quiet breathing as they do during the forced expiratory vital capacity manoeuvre, and this has been taken as an indicator of expiratory flow limitation at rest (EFLT. Therefore, EFLT, namely attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation, with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in Global Initiative for Chronic Obstructive Lung Disease III and IV stage, in whom the latter symptoms are common, but is not exclusive to COPD, since it can also be detected in other pulmonary and nonpulmonary diseases like asthma, acute respiratory distress syndrome, heart failure and obesity, etc. The existing up to date physiological techniques of assessing EFLT are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, noninvasive, practical and accurate new technique.

  14. Tidal exchange of larvae of Sesarma catenata (Decapoda, Brachyura)

    African Journals Online (AJOL)


    Oct 2, 1992 ... bimonthly during spring and neap tides from October to March at the tidal inlet. Samples were collected hourly for 25 h in February, and for 13 h in all other months. Hourly estimates of water flux through the tidal inlet of the estuary were calculated using a generalized one-dimensional hydrodynamic model ...

  15. Wave and tidal generation devices reliability and availability

    CERN Document Server

    Tavner, Peter John


    To some extent the wave and tidal generation industry is following in the wake of the wind industry, learning from the growing experience of offshore wind farm deployment. This book combines wind industry lessons with wave and tidal field knowledge to explore the main reliability and availability issues facing this growing industry.

  16. The Simulation Of Residual Tidal Phenomena In The White Sea (United States)

    May, R. I.


    Residual tidal phenomena (residual tidal circulation and residual tidal level) in the White Sea play a significant role in energy contribution to the formation of the hydrological regime. Non-linear residual tidal currents and sea level due to energy exchanges from the basic harmonics to the high frequency part of the spectrum have been poorly investigated in the White Sea until now. But residual tidal phenomena play an important role in the general circulation, which affects the temperature distribution and the drift of ice, plankton, pollution and other conservative tracers. We carried out numerical experiments with a non-linear hydrodynamic model to estimate the contributions of (shallow, friction and convective) nonlinearities to the residual tidal phenomena of White Sea's, using a `consecutive realisation' technique. The model grid's spatio-temporal resolution is more detailed than before: the Earth's geoid is approximated by the Krasovskiy rotation ellipsoid. A residual tidal level is observed in the low frequency part of spectrum of model results. In the linear approximation, the spectral density has a dominant peak at the frequencies of the basic harmonics in all parts of the sea, and the residual level was absent; overtones were not expressed. The experiments revealed that the residual circulation was defined by the convective non-linearity. The Earth's rotation does not change the current structure: only the circulation intensity decreases. These results will enhance the knowledge of tidal phenomena in the White Sea, and can be used for navigation, ecology and fisheries research.

  17. Ammonium transformation in a nitrogen-rich tidal freshwater marsh

    NARCIS (Netherlands)

    Gribsholt, B.; Struyf, E.; Tramper, A.; Andersson, M.G.I.; Brion, N.; de Brabandere, L.; van Damme, S.; Meire, P.; Middelburg, J.J.; Dehairs, F.; Boschker, H.T.S.


    The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH 4 + to the flood water entering a 3477 m2 tidal freshwater marsh

  18. Carbon dioxide uptake by a temperate tidal sea

    NARCIS (Netherlands)

    Klaassen, Wim


    Carbon dioxide (CO2) exchange between the atmosphere and the Wadden Sea, a shallow coastal region along the northern Netherlands, has been measured from April 2006 onwards on a tidal flat and over open water. Tidal flat measurements were done using a flux chamber, and ship borne measurements using

  19. Optical discovery of probable stellar tidal discruption flares

    NARCIS (Netherlands)

    van Velzen, S.; Farrar, G.R.; Gezari, S.; Morrell, N.; Zaritsky, D.; Ostman, L.; Smith, M.; Gelfand, J.; Drake, A.J.


    Using archival Sloan Digital Sky Survey (SDSS) multi-epoch imaging data (Stripe 82), we have searched for the tidal disruption of stars by supermassive black holes in non-active galaxies. Two candidate tidal disruption events (TDEs) are identified. The TDE flares have optical blackbody temperatures

  20. On the superposition of bedforms in a tidal channel

    DEFF Research Database (Denmark)

    Winter, C; Vittori, G.; Ernstsen, V.B.


    High resolution bathymetric measurements reveal the super-imposition of bedforms in the Grådyb tidal inlet in the Danish Wadden Sea. Preliminary results of numerical model simulations are discussed: A linear stability model was tested to explain the large bedforms as being caused by tidal system ...

  1. Tidal and gravity waves study from the airglow measurements at ...

    Indian Academy of Sciences (India)

    The other waves may be the upward propagating gravity waves or waves resulting from the interaction of inter-mode tidal oscillations, interaction of tidal waves with planetary waves and gravity waves. Some times, the second harmonic wave has higher vertical velocity than the corresponding fundamental wave. Application ...

  2. Simulating tidal turbines with multi-scale mesh optimisation techniques

    NARCIS (Netherlands)

    Abolghasemi, M.A.; Piggott, M.D.; Spinneken, J; Viré, A.C.; Cotter, CJ; Crammond, S.


    Embedding tidal turbines within simulations of realistic large-scale tidal flows is a highly multi-scale problem that poses significant computational challenges. Here this problem is tackled using actuator disc momentum (ADM) theory and Reynolds-averaged Navier–Stokes (RANS) with, for the first

  3. Modeling of channel patterns in short tidal basins

    NARCIS (Netherlands)

    Marciano, R.; Wang, Z.B.; Hibma, A.; De Vriend, H.J.; Defina, A.


    We model branching channel patterns in short tidal basins with two methods. A theoretical stability analysis leads to a relationship between the number of channels and physical parameters of the tidal system. The analysis reveals that width and spacing of the channels should decrease as the slope of

  4. Are Wave and Tidal Energy Plants New Green Technologies? (United States)

    Douziech, Mélanie; Hellweg, Stefanie; Verones, Francesca


    Wave and tidal energy plants are upcoming, potentially green technologies. This study aims at quantifying their various potential environmental impacts. Three tidal stream devices, one tidal range plant and one wave energy harnessing device are analyzed over their entire life cycles, using the ReCiPe 2008 methodology at midpoint level. The impacts of the tidal range plant were on average 1.6 times higher than the ones of hydro-power plants (without considering natural land transformation). A similar ratio was found when comparing the results of the three tidal stream devices to offshore wind power plants (without considering water depletion). The wave energy harnessing device had on average 3.5 times higher impacts than offshore wind power. On the contrary, the considered plants have on average 8 (wave energy) to 20 (tidal stream), or even 115 times (tidal range) lower impact than electricity generated from coal power. Further, testing the sensitivity of the results highlighted the advantage of long lifetimes and small material requirements. Overall, this study supports the potential of wave and tidal energy plants as alternative green technologies. However, potential unknown effects, such as the impact of turbulence or noise on marine ecosystems, should be further explored in future research.

  5. Temporal bed level variations in the Yangtze tidal flats (abstract)

    NARCIS (Netherlands)

    Yan, H.; Van Prooijen, B.C.


    The Yangtze River is one of the largest rivers in the world and the longest one in Asia. Its estuary forms an important entrance for shipping, but is also a key ecological system. Especially the inter-tidal flats are valuable habitats. The health and integrity of the estuarine tidal flat are however

  6. 4DCT-based assessment of regional airflow distribution in healthy human lungs during tidal breathing (United States)

    Choi, Jiwoong; Jahani, Nariman; Choi, Sanghun; Hoffman, Eric; Lin, Ching-Long


    Nonlinear dynamics of regional airflow distribution in healthy human lungs are studied with four-dimensional computed tomography (4DCT) quantitative imaging of four subjects. During the scanning session, subjects continuously breathed with tidal volumes controlled by the dual piston system. For each subject, 10 instantaneous volumetric image data sets (5 inspiratory and 5 expiratory phases) were reconstructed. A mass-preserving image registration was then applied to pairs of these image data to construct a breathing lung model. Regional distributions of local flow rate fractions are computed from time-varying local air volumes. The 4DCT registration-based method provides the link between local and global air volumes of the lung, allowing derivation of time-varying regional flow rates during the tidal breathing for computational fluid dynamics analysis. The local flow rate fraction remains greater in the lower lobes than in the upper lobes, being qualitatively consistent with those derived from three static CT (3SCT) images (Yin et al. JCP 2013). However, unlike 3SCT, the 4DCT data exhibit lung hysteresis between inspiration and expiration, providing more sensitive measures of regional ventilation and lung mechanics. NIH Grants U01-HL114494, R01-HL094315 and S10-RR022421.

  7. A stand-alone tidal prediction application for mobile devices (United States)

    Tsai, Cheng-Han; Fan, Ren-Ye; Yang, Yi-Chung


    It is essential for people conducting fishing, leisure, or research activities at the coasts to have timely and handy tidal information. Although tidal information can be found easily on the internet or using mobile device applications, this information is all applicable for only certain specific locations, not anywhere on the coast, and they need an internet connection. We have developed an application for Android devices, which allows the user to obtain hourly tidal height anywhere on the coast for the next 24 hours without having to have any internet connection. All the necessary information needed for the tidal height calculation is stored in the application. To develop this application, we first simulate tides in the Taiwan Sea using the hydrodynamic model (MIKE21 HD) developed by the DHI. The simulation domain covers the whole coast of Taiwan and the surrounding seas with a grid size of 1 km by 1 km. This grid size allows us to calculate tides with high spatial resolution. The boundary conditions for the simulation domain were obtained from the Tidal Model Driver of the Oregon State University, using its tidal constants of eight constituents: M2, S2, N2, K2, K1, O1, P1, and Q1. The simulation calculates tides for 183 days so that the tidal constants for the above eight constituents of each water grid can be extracted by harmonic analysis. Using the calculated tidal constants, we can predict the tides in each grid of our simulation domain, which is useful when one needs the tidal information for any location in the Taiwan Sea. However, for the mobile application, we only store the eight tidal constants for the water grids on the coast. Once the user activates the application, it reads the longitude and latitude from the GPS sensor in the mobile device and finds the nearest coastal grid which has our tidal constants. Then, the application calculates tidal height variation based on the harmonic analysis. The application also allows the user to input location and

  8. Confusion around the tidal force and the centrifugal force

    CERN Document Server

    Matsuda, Takuya; Boffin, Henri M J


    We discuss the tidal force, whose notion is sometimes misunderstood in the public domain literature. We discuss the tidal force exerted by a secondary point mass on an extended primary body such as the Earth. The tidal force arises because the gravitational force exerted on the extended body by the secondary mass is not uniform across the primary. In the derivation of the tidal force, the non-uniformity of the gravity is essential, and inertial forces such as the centrifugal force are not needed. Nevertheless, it is often asserted that the tidal force can be explained by the centrifugal force. If we literally take into account the centrifugal force, it would mislead us. We therefore also discuss the proper treatment of the centrifugal force.

  9. Quantification of tidal parameters from Solar System data (United States)

    Lainey, Valéry


    Tidal dissipation is the main driver of orbital evolution of natural satellites and a key point to understand the exoplanetary system configurations. Despite its importance, its quantification from observations still remains difficult for most objects of our own Solar System. In this work, we overview the method that has been used to determine, directly from observations, the tidal parameters, with emphasis on the Love number k_2 and the tidal quality factor Q. Up-to-date values of these tidal parameters are summarized. Last, an assessment on the possible determination of the tidal ratio k_2/Q of Uranus and Neptune is done. This may be particularly relevant for coming astrometric campaigns and future space missions focused on these systems.

  10. Genève grandeur cultures.

    Directory of Open Access Journals (Sweden)

    Vincent Kaufmann


    Full Text Available Equinoxe , revue genevoise de sciences humaines, consacre son dernier numéro à l’émergence et au développement des contre-cultures à Genève depuis la fin des années 1960. Celui-ci se présente comme « une réflexion critique sur trois décennies de pratiques culturelles et sur la manière dont celles-ci sont parvenues non sans heurts à se faire une place dans la cité ». L’intérêt de la démarche réside dans le fait qu’à Genève, contrairement à Berlin, Paris, Barcelone ...

  11. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databasesBASE, CAB Abstracts, CAS (Chemical Abstracts Service, DOAJ, EBSCO Discovery Service (EDS, Google Scholar, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  12. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databasesBASE, CAB Abstracts, CAS (Chemical Abstracts Service, CiteFactor, DOAJ, DRJI, EBSCO Discovery Service (EDS, Google Scholar, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  13. Din ve Kişilik


    GÖCEN, Gülüşan


    1 Robert A. Emmons ,“Religion and Personality”, (Ed.) Harold G. Koing, Handbook of Religion and Mental Health . California, 1998, Akademik Press. 2 California Üniversitesi Psikoloji Bölümü, Davis Davis California 95616. 3 Dr., Din Kültürü ve Ahlak Bilgisi Öğretmeni, Bayrampaşa İmam Hatip Ortaokulu. İstanbul,

  14. The ocean response at multiple space and time scales to tidal stream energy extraction by a large-scale turbine array. (United States)

    De Dominicis, Michela; O'Hara Murray, Rory; Wolf, Judith


    A comprehensive assessment of the tidal energy resource realistically available for electricity generation and the study of the potential environmental impacts associated with its extraction in the Pentland Firth (Scottish Waters, UK) are presented. In order to examine both local (100 km) spatial scales, the Scottish Shelf Model (SSM), an unstructured grid three-dimensional FVCOM (Finite Volume Community Ocean Model) model implementation has been used, since it covers the entire NW European Shelf, with a high resolution where the tidal stream energy is extracted. A large theoretical array of tidal stream turbines has been designed and implemented in the model using the momentum sink approach, in which a momentum sink term represents the loss of momentum due to tidal energy extraction. The estimate of the maximum available power for electricity generation from the Pentland Firth is 1.64 GW, which requires thousands of turbines to be deployed. This estimate takes into account the tidal stream energy extraction feedbacks on the flow and considers, for the first time, the realistic operation of a generic tidal stream turbine, which is limited to operate in a range of flow velocities due to technological constraints. The ocean response to the extraction of 1.64 GW of energy has been examined by comparing a typical annual cycle of the NW European Shelf hydrodynamics reproduced by the SSM with the same period perturbed by tidal stream energy extraction. The changes were analysed at the temporal scale of a spring-neap tidal cycle and, for the first time, on longer term seasonal timescales. Tidal elevation mainly increases in the vicinity of the tidal farm, while far-field effects show a decrease in the mean spring tidal range of the order of 2 cm along the whole east coast of the UK, possibly counteracting some part of the predicted sea level rise due to climate change. Marine currents, both tidal and residual flows, are also affected. They can slow down due to the

  15. NS begins tidal power test with 1 turbine

    Energy Technology Data Exchange (ETDEWEB)



    The Bay of Fundy holds huge potential as a source of clean renewable tidal energy. This article announced the successful installation of a turbine that will test the potential of tidal power in the Bay of Fundy. Rather than requiring any dams or head ponds, new tidal power technologies include offshore floating tidal turbines and turbines that are anchored to the ocean floor to take advantage of natural tidal flows. In September 2009, Nova Scotia Power unveiled the 1 MW Open-Centre tidal turbine that was manufactured in Ireland by OpenHydro. The 10-metre turbine will be deployed in the Minas Passage as part of the Fundy Ocean Research Centre for Energy (FORCE) tidal test site. The turbine will rest directly on the ocean floor using a subsea gravity base made in Dartmouth by Cherubini Metal Works. It has several design features that minimize the impact on marine life. A large open centre provides a safe passage for marine life and the turbine's clean hydrodynamic lines ensure that fish will not become entangled. The use of oils, greases and other lubricants has also been avoided. The unit produces only very low levels of mechanical noise. A detailed turbine and environmental monitoring program will begin upon completion of the installation. Nova Scotia Power's involvement with the tidal energy test facility is supported by Sustainable Development Technology Canada. Nova Scotia Hydro owns and operates 1 of only 3 tidal power plants in the world, and the only one in the western hemisphere. The Annapolis Tidal Power plant, which came online in 1984, has a capacity of 20 MW and a daily output of about 80 to 100 megawatt hours.

  16. Filizlenen okuryazarlık ve desteklenmesi

    Directory of Open Access Journals (Sweden)

    Berrin Baydık


    Full Text Available Günümüzde, erken okuryazarlık eğitimcileri ve diğer uzmanlar okuryazarlık gelişiminin çocukluğun çok erken dönemlerinde başladığına inanmaktadırlar. Filizlenen okuryazarlık terimi günümüz okuryazarlık gelişimi görüşünü betimlemek için kullanılmaktadır. Bu derlemede, filizlenen okuryazarlık görüşünün özellikleri, filizlenen okuryazarlık bilgi ve becerilerinin iki alanı; yazılı dil farkındalığı ve sesbilgisel farkındalık betimlenmiştir. Ayrıca bu alanların nasıl destekleneceği açıklanmıştır. Today, early childhood educators and other professionals believe that literacy development begins in the very early stages of childhood. Emergent literacy is a term used to describe the present day view of early literacy development. In this review, the characteristics of the notion of emergent literacy and two domains of emergent literacy knowledge and skills; written language awareness and phonological awareness were described. ln addition, how these domains were promoted was explained.

  17. Ocean tidal loading affecting precise geodetic observations on Greenland: Error account of surface deformations by tidal gravity measurements

    DEFF Research Database (Denmark)

    Jentzsch, G.; Knudsen, Per; Ramatschi, M.


    observations. Near the coast ocean tidal loading causes additional vertical deformations in the order of 1 to 10 cm Therefore, tidal gravity measurements were carried out at four fiducial sites around Greenland in order to provide corrections for the kinematic part of the coordinates of these sites. Starting...

  18. Three-dimensional semi-idealized model for tidal motion in tidal estuaries: an application to the Ems estuary

    NARCIS (Netherlands)

    Kumar, Mohit; Schuttelaars, H.M.; Roos, Pieter C.; Möller, M.


    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the

  19. A process study of the interaction of tidal currents, tidal mixing and density gradients in a region of freshwater influence (United States)

    Xing, Jiuxing; Chen, Shengli


    A three dimensional unstructured grid model of the west coast of Britain is used to study the process of the interaction of tidal currents, tidal mixing and density gradient in the Liverpool Bay region. Calculations with M2 tidal forcing and omitting freshwater discharge show that tidal currents in the region are strong (of order 1 ms- 1), with tidal current ellipses essentially rectilinear in the surface and bottom. In the absence of tidal forcing, the freshwater is confined to a thin surface layer. With the inclusion of tidal mixing the surface layer thickens, and in the shallow water area mixed layer occupies the whole water depth. This has a significant effect of reducing its lateral spread. A detailed study of time series of velocity, salinity and turbulence reveals that at flood tide, more saline water is advected into the coastal region and rapid vertical mixing occurs, whereas at ebb tide, fresher water is advected over more saline water. The induced strong pycnocline uncouples surface and bottom layers leading to more circular tidal ellipses which rotate in opposite directions in the vertical, as found in observations. The three dimensional nature of the model reveals that this process involves both horizontal and vertical density gradients, and shows significant horizontal variability in the Liverpool Bay region.

  20. Ultraviolet Spectroscopy of Tidal Disruption Flares (United States)

    Cenko, Stephen B.


    When a star passes within the sphere of disruption of a massive black hole, tidal forces will overcome self-gravity and unbind the star. While approximately half of the stellar debris is ejected at high velocities, the remaining material stays bound to the black hole and accretes, resulting in a luminous, long-lived transient known as a tidal disruption flare (TDF). In addition to serving as unique laboratories for accretion physics,TDFs offer the hope of measuring black hole masses in galaxies much too distant for resolved kinematic studies.In order to realize this potential, we must better understand the detailed processes by which the bound debris circularizes and forms an accretion disk. Spectroscopy is critical to this effort, as emission and absorption line diagnostics provide insight into the location and physical state (velocity, density, composition) of the emitting gas (in analogy with quasars). UV spectra are particularly critical, as most strong atomic features fall in this bandpass, and high-redshift TDF discoveries from LSST will sample rest-frame UV wavelengths.Here I present recent attempts to obtain UV spectra of tidal disruption flares. I describe the UV spectrum of ASASSN-14li, in which we detect three classes of features: narrow absorption from the Milky Way (probably a high-velocity cloud), and narrow absorption and broad (2000-8000 km s-1) emission lines at or near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by 250-400 km s-1. Due both to this velocity offset and the lack of common low-ionization features (Mg II, Fe II), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N III], N IV], and He II are quite prominent, while the common quasar emission lines of C III] and Mg II are weak or entirely absent. Detailed modeling of this spectrum will

  1. El’ Lisickij grafico costruttivista. La rivista “Vešč’-Gegenstand-Objet”

    Directory of Open Access Journals (Sweden)

    Alice Bravin


    Full Text Available This paper analyzes the graphic design of the international art journal “Vešč’-Gegenstand-Objet”, published in Berlin in 1922 by the Russian architect, painter, photographer and designer Lazar’ Markovič Lisickij (1890-1941, better known as El’ Lisickij, together with the Russian writer Il’ja Grigor’evič Èrenburg (1891-1967.Although it lasted only three issues (issues one and two were combined in a single volume which appeared in March/April 1922, while the last number appeared in May 1922, “Vešč’” had a strong influence on contemporary art. It was published in German, French and Russian and was meant both as a bridge between Russia and Europe after the years of war and revolution and as a symbol of the beginning of a new creative era. Mainly focusing on new Suprematist and Constructivist works, the journal included essays on several fields of art such as literature, cinema, theatre, painting, sculpture, architecture and music.In this paper I focus on the innovative graphic design of the two volumes of “Vešč’” entirely realized by El’ Lisickij. Referring to his own theories about book design, Lisickij created a functional and innovative layout and a striking cover, challenging the traditional graphic design practice by using exclusively standard typographic elements such as punctuation marks, typographic lines, geometric forms and typesetting.

  2. Waddenfonds Tidal Texel Demonstration project. BlueTEC Texel Tidal Project: Environmental measurement and performance analysis


    Ponsoni, L.; Nauw, J. J.; Smit, M.; Ober, S.; Nichols, C; Kenkhuis, J.; Schmidt, C.; Buatois, A.; Haas, P.


    In the context of the BlueTEC project, this report starts by introducing theBlueTEC tidal energy platform and reviewing the patterns of circulation of theMarsdiep inlet. The energy resource assessment and the site selection for theplatform's deployment are reported. This document analyses di?erent datasetssampled during the project, including current speeds, wave parameters, turbinepower output, platform excursions, and environmental parameters. Most of thedata was measured by instruments ins...

  3. Slow Rotating Trojans: Tidally Synchronized Binaries? (United States)

    Noll, Keith


    We propose HST observations of six slow-rotating Trojans to search for tidally synchronous binaries similar to the Patroclus binary system. A significant excess of slow rotators over Maxwellian suggests that additional binaries may be present. If any of the targets are binary, they can be resolved by HST. This target selection strategy has recently yielded the third known resolved Trojan binary, detected in a sample of seven slow-rotating Trojans. We wish to extend this successful strategy with another similarly selected sample. Even one additional resolved binary in the Trojans, which would become the fourth, would be of extreme interest. The discovery of no binaries among this group of slow rotators would challenge the understanding of the source of the excess slow rotators in the Trojans.

  4. Using very high frequencies with very low lung volumes during high-frequency oscillatory ventilation to protect the immature lung. A pilot study. (United States)

    González-Pacheco, N; Sánchez-Luna, M; Ramos-Navarro, C; Navarro-Patiño, N; de la Blanca, A R-S


    High-frequency oscillatory ventilation (HFOV) has been described as a rescue therapy in severe respiratory distress syndrome (RDS) with a potential protective effect in immature lungs. In recent times, HFOV combined with the use of volume guarantee (VG) strategy has demonstrated an independent effect of the frequency on tidal volume to increase carbon-dioxide (CO2) elimination. The aim of this study was to demonstrate the feasibility of using the lowest tidal volume on HFOV+VG to prevent lung damage, maintaining a constant CO2 elimination by increasing the frequency. Newborn infants with RDS on HFOV were prospectively included. After adequate and stable ventilation using a standard HFOV strategy, the tidal volume was fixed using VG and decreased while the frequency was increased to the highest possible to maintain a constant CO2 elimination. Pre- and post-PCO2, delta pressure and tidal volume obtained in each situation were compared. Twenty-three newborn infants were included. It was possible to increase the frequency while decreasing the tidal volume in all patients, maintaining a similar CO2 elimination, with a tendency to a lower mean PCO2 after reaching the highest frequency. High-frequency tidal volume was significantly lower, 2.20 ml kg(-1) before vs 1.59 ml kg(-1) at the highest frequency. It is possible to use lower delivered tidal volumes during HFOV combined with VG and higher frequencies with adequate ventilation to allow minimizing lung injury.

  5. Tidal constraints on the interior of Venus (United States)

    Dumoulin, Caroline; Tobie, Gabriel; Verhoeven, Olivier; Rosenblatt, Pascal; Rambaux, Nicolas


    As a prospective study for a future exploration of Venus, we propose to systematically investigate the signature of the internal structure in the gravity field and the rotation state of Venus, through the determination of the moment of inertia and the tidal Love number.We test various mantle compositions, core size and density as well as temperature profiles representative of different scenarios for formation and evolution of Venus. The mantle density ρ and seismic vP and vS wavespeeds are computed in a consistent manner from given temperature and composition using the Perple X program. This method computes phase equilibria and uses the thermodynamics of mantle minerals developped by Stixrude and Lithgow-Bertelloni (2011).The viscoelastic deformation of the planet interior under the action of periodic tidal forces are computed following the method of Tobie et al. (2005).For a variety of interior models of Venus, the Love number, k2, and the moment of inertia factor are computed following the method described above. The objective is to determine the sensitivity of these synthetic results to the internal structure. These synthetic data are then used to infer the measurement accuracies required on the time-varying gravitational field and the rotation state (precession rate, nutation and length of day variations) to provide useful constraints on the internal structure.We show that a better determination of k2, together with an estimation of the moment of inertia, the radial displacement, and of the time lag, if possible, will refine our knowledge on the present-day interior of Venus (size of the core, mantle temperature, composition and viscosity). Inferring these quantities from a future ex- ploration mission will provide essential constraints on the formation and evolution scenarios of Venus.

  6. Magnetic field evolution in tidal disruption events (United States)

    Bonnerot, Clément; Price, Daniel J.; Lodato, Giuseppe; Rossi, Elena M.


    When a star gets tidally disrupted by a supermassive black hole, its magnetic field is expected to pervade its debris. In this paper, we study this process via smoothed particle magnetohydrodynamical simulations of the disruption and early debris evolution including the stellar magnetic field. As the gas stretches into a stream, we show that the magnetic field evolution is strongly dependent on its orientation with respect to the stretching direction. In particular, an alignment of the field lines with the direction of stretching induces an increase of the magnetic energy. For disruptions happening well within the tidal radius, the star compression causes the magnetic field strength to sharply increase by an order of magnitude at the time of pericentre passage. If the disruption is partial, we find evidence for a dynamo process occurring inside the surviving core due to the formation of vortices. This causes an amplification of the magnetic field strength by a factor of ˜10. However, this value represents a lower limit since it increases with numerical resolution. For an initial field strength of 1 G, the magnetic field never becomes dynamically important. Instead, the disruption of a star with a strong 1 MG magnetic field produces a debris stream within which magnetic pressure becomes similar to gas pressure a few tens of hours after disruption. If the remnant of one or multiple partial disruptions is eventually fully disrupted, its magnetic field could be large enough to magnetically power the relativistic jet detected from Swift J1644+57. Magnetized streams could also be significantly thickened by magnetic pressure when it overcomes the confining effect of self-gravity.

  7. Dynamics of Tidally Locked, Ultrafast Rotating Atmospheres (United States)

    Tan, Xianyu; Showman, Adam P.


    Tidally locked gas giants, which exhibit a novel regime of day-night thermal forcing and extreme stellar irradiation, are typically in several-day orbits, implying slow rotation and a modest role for rotation in the atmospheric circulation. Nevertheless, there exist a class of gas-giant, highly irradiated objects - brown dwarfs orbiting white dwarfs in extremely tight orbits - whose orbital and hence rotation periods are as short as 1-2 hours. Spitzer phase curves and other observations have already been obtained for this fascinating class of objects, which raise fundamental questions about the role of rotation in controlling the circulation. So far, most modeling studies have investigated rotation periods exceeding a day, as appropriate for typical hot Jupiters. In this work we investigate the dynamics of tidally locked atmospheres in shorter rotation periods down to about two hours. With increasing rotation rate (decreasing rotation period), we show that the width of the equatorial eastward jet decreases, consistent with the narrowing of wave-mean-flow interacting region due to decrease of the equatorial deformation radius. The eastward-shifted equatorial hot spot offset decreases accordingly, and the westward-shifted hot regions poleward of the equatorial jet associated with Rossby gyres become increasingly distinctive. At high latitudes, winds becomes weaker and more geostrophic. The day-night temperature contrast becomes larger due to the stronger influence of rotation. Our simulated atmospheres exhibit small-scale variability, presumably caused by shear instability. Unlike typical hot Jupiters, phase curves of fast-rotating models show an alignment of peak flux to secondary eclipse. Our results have important implications for phase curve observations of brown dwarfs orbiting white dwarfs in ultra tight orbits.

  8. Ambient Noise in an Urbanized Tidal Channel (United States)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  9. Dwarf Galaxies Swimming in Tidal Tails (United States)


    This false-color infrared image from NASA's Spitzer Space Telescope shows little 'dwarf galaxies' forming in the 'tails' of two larger galaxies that are colliding together. The big galaxies are at the center of the picture, while the dwarfs can be seen as red dots in the red streamers, or tidal tails. The two blue dots above the big galaxies are stars in the foreground. Galaxy mergers are common occurrences in the universe; for example, our own Milky Way galaxy will eventually smash into the nearby Andromeda galaxy. When two galaxies meet, they tend to rip each other apart, leaving a trail, called a tidal tail, of gas and dust in their wake. It is out of this galactic debris that new dwarf galaxies are born. The new Spitzer picture demonstrates that these particular dwarfs are actively forming stars. The red color indicates the presence of dust produced in star-forming regions, including organic molecules called polycyclic aromatic hydrocarbons. These carbon-containing molecules are also found on Earth, in car exhaust and on burnt toast, among other places. Here, the molecules are being heated up by the young stars, and, as a result, shine in infrared light. This image was taken by the infrared array camera on Spitzer. It is a 4-color composite of infrared light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). Starlight has been subtracted from the orange and red channels in order to enhance the dust features.

  10. Tidal River Management (TRM and Tidal Basin Management (TBM: A case study on Bangladesh

    Directory of Open Access Journals (Sweden)

    Talchabhadel Rocky


    Full Text Available Bangladesh is the biggest delta of the world. Construction of numbers of polders is one of the flood resilient approach. But the presence of coastal polders de-linked the flood plain. The siltation in river causes riverbeds to become higher than the adjacent crop lands, and vast area under the polders became permanently water logged rendering large tract of land uncultivable. The current practice is temporarily de-poldering by cutting embankment. This is a natural water management process with very little human interventions but it needs strong participation and consensus with a great deal of sacrifice by the stakeholders for a specific period (3 to 5 years or even more[1]. An attempt has been made to study the phenomena of tidal basin management reviewing some secondary data and processes involved in successfully operated tidal basins of Bangladesh. And preliminary laboratory experiments are carried out to precisely look into the suspended sediment transport. With varying outflow discharge and sediment supply, the transport processes are investigated. 3D sediment transport model developed using openFOAM has good agreement with experimental result and can be used to better understand effectiveness of tidal basin management.

  11. Variations in tidal level in the Gulf of Mexico and implications for tidal wetlands (United States)

    Stumpf, R.P.; Haines, J.W.


    Tidal wetland environments have an ecological zonation that corresponds with tide levels, in particular with mean high water. However, mean sea level (MSL), which has shown a persistent rise in the Gulf of Mexico during this century, is the most common reference for water level change. We examine here the relationship between mean sea level and mean high water in describing water level changes in the Gulf of Mexico. The records of monthly mean water level for four stations, Galveston, Pensacola, Cedar Key and Key West, are partitioned into the annual cycle, the long-term trend, and a low-frequency (> 10 year period) fluctuation. The trend is the same for MSL and mean higher high water (MHHW) for all stations investigated except Cedar Key, Florida, where MHHW has increased more rapidly than MSL. The low-frequency fluctuations are similar between the stations and the tidal datums. MSL can predict MHHW with discrepancies of up to 5 cm owing to the lunar nodal cycle and an annual tidal signal. Low-frequency climatic fluctuations produce greater variations than the nodal cycle, but the difference in frequency can lead to interference between the two in MHHW. The combination of the two can produce sea-level rises in excess of 1 cm year-1 over several year periods, even in areas having long-term trends of 0.2 cm year-1 or less.

  12. Assessment of tidal circulation and tidal current asymmetry in the Iroise sea with specific emphasis on characterization of tidal energy resources around the Ushant Island. (United States)

    Thiébaut, Maxime; Sentchev, Alexei


    We use the current velocity time series recorded by High Frequency Radars (HFR) to study circulation in highly energetic tidal basin - the Iroise sea. We focus on the analysis of tidal current pattern around the Ushant Island which is a promising site of tidal energy. The analysis reveals surface current speeds reaching 4 m/s in the North of Ushant Island and in the Fromveur Strait. In these regions 1 m/s is exceeded 60% of time and up to 70% of time in center of Fromveur. This velocity value is particularly interesting because it represents the cut-in-speed of the most of marine turbine devices. Tidal current asymmetry is not always considered in tidal energy site selection. However, this quantity plays an important role in the quantification of hydrokinetic resources. Current velocity times series recorded by HFR highlights the existence of a pronounced asymmetry in current magnitude between the flood and ebb tide ranging from -0.5 to more 2.5. Power output of free-stream devices depends to velocity cubed. Thus a small current asymmetry can generate a significant power output asymmetry. Spatial distribution of asymmetry coefficient shows persistent pattern and fine scale structure which were quantified with high degree of accuracy. The particular asymmetry evolution on both side of Fromveur strait is related to the spatial distribution of the phase lag of the principal semi-diurnal tidal constituent M2 and its higher order harmonics. In Fromveur, the asymmetry is reinforced due to the high velocity magnitude of the sixth-diurnal tidal harmonics. HF radar provides surface velocity speed, however the quantification of hydrokinetic resources has to take into account the decreasing of velocity with depth. In order to highlight this phenomenon, we plot several velocity profiles given by an ADCP which was installed in the HFR study area during the same period. The mean velocity in the water column calculated by using the ADCP data show that it is about 80% of the

  13. Slope-induced tidal straining: Analysis of rotational effects (United States)

    Schulz, Kirstin; Endoh, Takahiro; Umlauf, Lars


    Tidal straining is known to be an important factor for the generation of residual currents and transports of suspended matter in the coastal ocean. Recent modeling studies and field experiments have revealed a new type of "slope-induced" tidal straining, in which the horizontal density gradient required for this process is induced by the presence of a slope rather than by river runoff (as in classical tidal straining). Slope-induced tidal straining is investigated here with the help of an idealized numerical model, and results are compared to a recent data set from the East China Sea providing first direct observational evidence. The focus of this study is on the effect of rotation that was ignored in previous investigations. The model is shown to reproduce the key features of the observations, in particular the strain-induced generation of unstable stratification in the bottom boundary layer during periods of upslope flow. Rotation effects are found to significantly reduce the upslope tidal pumping of suspended material and also give rise to a newly identified pumping mechanism that results in a vigorous transport of suspended material along the slope. It is shown that slope-induced tidal straining is likely to be relevant for a wide range of oceanic slopes exposed to tidal motions.

  14. A new high resolution tidal model in the arctic ocean

    DEFF Research Database (Denmark)

    Cancet, M.; Andersen, Ole Baltazar; Lyard, F.

    The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence, the accu...... for assimilation and validation. This paper presents the performances of this new regional tidal model in the Arctic Ocean, compared to the existing global tidal models.......The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence......-growing maritime and industrial activities in this region. NOVELTIS and DTU Space have developed a regional, high-resolution tidal atlas in the Arctic Ocean, in the framework of the CryoSat Plus for Ocean (CP4O) ESA project. In particular, this atlas benefits from the assimilation of the most complete satellite...

  15. Magnetic fields driven by tidal mixing in radiative stars (United States)

    Vidal, J.; Cébron, D.; Schaeffer, N.; Hollerbach, R.


    Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 % of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the question of their origin. These stars host outer radiative envelopes, which are stably stratified. Therefore, they are assumed to be motionless in standard models of stellar structure and evolution. We focus on rapidly rotating, radiative stars which may be prone to the tidal instability, due to an orbital companion. Using direct numerical simulations in a sphere, we study the interplay between a stable stratification and the tidal instability, and assess its dynamo capability. We show that the tidal instability is triggered regardless of the strength of the stratification (Brunt-Väisälä frequency). Furthermore, the tidal instability can lead to both mixing and self-induced magnetic fields in stably stratified layers (provided that the Brunt-Väisälä frequency does not exceed the stellar spin rate in the simulations too much). The application to stars suggests that the resulting magnetic fields could be observable at the stellar surfaces. Indeed, we expect magnetic field strengths up to several Gauss. Consequently, tidally driven dynamos should be considered as a (complementary) dynamo mechanism, possibly operating in radiative MS and PMS stars hosting orbital companions. In particular, tidally driven dynamos may explain the observed magnetism of tidally deformed and rapidly rotating Vega-like stars.

  16. Spatial Assessment of a Biocriteria Applied to Texas Tidal Streams

    Directory of Open Access Journals (Sweden)

    James M. Tolan


    Full Text Available This study reports on a derived multivariate method for assessing ecosystem health within tidally influenced portions of river basins and coastal basins. These tidally influenced areas are highly productive transitional areas which serve as important nursery areas for many fish and shellfish species. Numerous Texas tidal streams under varying degrees of anthropogenic stressors were analyzed jointly with this new, standardized methodology. Physical and chemical constituents of the tidal systems, as well as their resident nekton communities, were compared with nonparametric ordination techniques in order to uncover a biocriteria that might have general applicability over large spatial scales. All of the tidal stream communities were dominated by only a few taxa that each displays tremendous euryhaline/physiological tolerances, and these abilities allow taxa utilizing tidal streams to adapt to a wide variety of environmental stressors. The absence of any clear connections between degraded water-bodies and any impaired nektonic communities should not automatically be viewed as a constraint inherent to the techniques of the methodology presented, but rather a verification that impaired tidal streams are not that common of an occurrence along the Texas coast, at least not when using nekton communities as the degradation indicator.

  17. Tidal day organic and inorganic material flux of ponds in the Liberty Island freshwater tidal wetland. (United States)

    Lehman, Peggy W; Mayr, Shawn; Liu, Leji; Tang, Alison


    The loss of inorganic and organic material export and habitat produced by freshwater tidal wetlands is hypothesized to be an important contributing factor to the long-term decline in fishery production in San Francisco Estuary. However, due to the absence of freshwater tidal wetlands in the estuary, there is little information on the export of inorganic and organic carbon, nutrient or phytoplankton community biomass and the associated mechanisms. A single-day study was conducted to assess the potential contribution of two small vegetated ponds and one large open-water pond to the inorganic and organic material flux within the freshwater tidal wetland Liberty Island in San Francisco Estuary. The study consisted of an intensive tidal day (25.5 h) sampling program that measured the flux of inorganic and organic material at three ponds using continuous monitoring of flow, chlorophyll a, turbidity and salt combined with discrete measurements of phytoplankton community carbon, total and dissolved organic carbon and nutrient concentration at 1.5 h intervals. Vegetated ponds had greater material concentrations than the open water pond and, despite their small area, contributed up to 81% of the organic and 61% of the inorganic material flux of the wetland. Exchange between ponds was important to wetland flux. The small vegetated pond in the interior of the wetland contributed as much as 72-87% of the total organic carbon and chlorophyll a and 10% of the diatom flux of the wetland. Export of inorganic and organic material from the small vegetated ponds was facilitated by small-scale topography and tidal asymmetry that produced a 40% greater material export on ebb tide. The small vegetated ponds contrasted with the large open water pond, which imported 29-96% of the inorganic and 4-81% of the organic material into the wetland from the adjacent river. This study identified small vegetated ponds as an important source of inorganic and organic material to the wetland and the

  18. A summary of the San Francisco tidal wetlands restoration series

    Directory of Open Access Journals (Sweden)

    Larry R. Brown


    Full Text Available The four topical articles of the Tidal Wetlands Restoration Series summarized and synthesized much of what is known about tidal wetlands and tidal wetland restoration in the San Francisco Estuary (hereafter “Estuary”. Despite a substantial amount of available information, major uncertainties remain. A major uncertainty with regard to fishes is the net benefit of restored tidal wetlands relative to other habitats for native fishes in different regions of the Estuary given the presence of numerous invasive alien species. With regard to organic carbon, a major uncertainty is the net benefit of land use change given uncertainty about the quantity and quality of different forms of organic carbon resulting from different land uses. A major challenge is determining the flux of organic carbon from open systems like tidal wetlands. Converting present land uses to tidal wetlands will almost certainly result in increased methylation of mercury at the local scale with associated accumulation of mercury within local food webs. However, it is unclear if such local accumulation is of concern for fish, wildlife or humans at the local scale or if cumulative effects at the regional scale will emerge. Based on available information it is expected that restored tidal wetlands will remain stable once constructed; however, there is uncertainty associated with the available data regarding the balance of sediment accretion, sea-level rise, and sediment erosion. There is also uncertainty regarding the cumulative effect of many tidal restoration projects on sediment supply. The conclusions of the articles highlight the need to adopt a regional and multidisciplinary approach to tidal wetland restoration in the Estuary. The Science Program of the CALFED effort provides an appropriate venue for addressing these issues.

  19. A simple approach to adjust tidal forcing in fjord models (United States)

    Hjelmervik, Karina; Kristensen, Nils Melsom; Staalstrøm, André; Røed, Lars Petter


    To model currents in a fjord accurate tidal forcing is of extreme importance. Due to complex topography with narrow and shallow straits, the tides in the innermost parts of a fjord are both shifted in phase and altered in amplitude compared to the tides in the open water outside the fjord. Commonly, coastal tide information extracted from global or regional models is used on the boundary of the fjord model. Since tides vary over short distances in shallower waters close to the coast, the global and regional tidal forcings are usually too coarse to achieve sufficiently accurate tides in fjords. We present a straightforward method to remedy this problem by simply adjusting the tides to fit the observed tides at the entrance of the fjord. To evaluate the method, we present results from the Oslofjord, Norway. A model for the fjord is first run using raw tidal forcing on its open boundary. By comparing modelled and observed time series of water level at a tidal gauge station close to the open boundary of the model, a factor for the amplitude and a shift in phase are computed. The amplitude factor and the phase shift are then applied to produce adjusted tidal forcing at the open boundary. Next, we rerun the fjord model using the adjusted tidal forcing. The results from the two runs are then compared to independent observations inside the fjord in terms of amplitude and phases of the various tidal components, the total tidal water level, and the depth integrated tidal currents. The results show improvements in the modelled tides in both the outer, and more importantly, the inner parts of the fjord.

  20. Excess molar volumes and isentropic compressibilities of binary ...

    Indian Academy of Sciences (India)

    Remaining five binary mixtures, n-heptane + toluene, cyclohexane + n-heptane, cyclohexane + n-hexane, toluene + nhexane and n-decane + n-hexane show negative excess molar volumes over the whole composition range. However, the large negative values of excess molar volume becomes dominant in toluene + ...

  1. Tidal analysis of data recorded by a superconducting gravimeter

    Directory of Open Access Journals (Sweden)

    F. Palmonari


    Full Text Available A superconducting gravimeter was used to monitor the tidal signal for a period of five months. The instrument was placed in a site (Brasimone station, Italy chat-acterized by a low noise level, and was calibrated with a precision of 0.2%. Then tidal analysis on hourly data was performed and the results presented in this paper; amplitudes, gravimetric factors, phase differences for the main tidal waves, M2, S2, N2, 01, Pl, K1, QI, were calculated together with barometric pressure admittance and long term instrumental drift.

  2. Motion of particles near a magnetized tidal charged black hole (United States)

    Sharif, M.; Kousar, Lubna


    This paper is devoted to study the effects of tidal charge on the motion of both neutral as well as charged particles around a magnetized tidal charged black hole. We analyze the innermost stable circular orbits and conditions for escape velocity. In order to discuss stability of orbits, we explore Lyapunov exponent and effective force on the particle. The center of mass energy of the interacting particles is studied in the presence/absence of external magnetic field. We conclude that the external magnetic field as well as tidal charge has a great influence on the particle's motion.

  3. Analysis of Tidal Data for Dagang Tidal Gauge and Study of the Changes for the National Height Datum

    Directory of Open Access Journals (Sweden)

    WU Fumei


    Full Text Available The main tides affecting Dagang sea level are analyzed and the national height datum is studied by analyzing 1980—2011 hourly tidal data and 1952—2007 monthly mean tidal data. Firstly, the frequencies and amplitudes of main tides including 180 short-period tides and 6 long-period tides are gained by the Fouirer transform. Then the actual amplitudes and their variations of main tides are obtained by the harmonic analysis of the 1980—2011 hourly tidal data, and the changes with about 19 year period can easily be found in the amplitudes of Q1、O1、M2、K1、K2. And then the changes of the mean sea level at Dagang tidal gauge defining national height datum during the period of 1952—2011 are studied by the harmonic analysis and the shifting average of 18.61 year tidal heights. The results of these methods show that the mean sea level at Dagang tidal gauge descended with the speed of 1.07 mm/a and 0.76 mm/a respectively during 1952—1980, and that it ascended with the speed of 1.59 mm/a and 1.62 mm/a respectively during 1980—2011. And finally the difference of 0.14 cm is achieved by the shifting average of 18.61 year tidal heights for 1985 National Height Datum.

  4. ve og døvblevne mennesker

    DEFF Research Database (Denmark)

    Larsen, Lena Bech; Lindsay Sommer, Mette; Bengtsson, Steen

    Denne rapport giver et bredt billede af levevilkår for personer i den erhvervsaktive alder (16-64 år), der er døve eller døvblevne. Samlet set er gruppen af døve og døvblevne dårligere stillet end befolkningsgennemsnittet i dagens Danmark. Både døve og døvblevne bliver i mindre grad uddannet, og...

  5. Linking freshwater tidal hydrology to carbon cycling in bottomland hardwood wetlands (United States)

    Carl C. Trettin; Brooke J. Czwartacki; Craig J. Allan; Devendra M. Amatya


    Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes in forested wetlands. However, the consequences of tidally mediated hydrology are seldom considered within forested wetlands that occur along tidal water bodies. These tidal water bodies may be either fresh or brackish, and the tidal streams function as a reservoir to...

  6. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databasesBASE, CAB Abstracts, CAS (Chemical Abstracts Service, CiteFactor, CNKI Scholar, DOAJ, DRJI, EBSCO Discovery Service (EDS, Google Scholar, Index Copernicus, InfoBase Index, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  7. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databases:BASE, CAB Abstracts, CAS (Chemical Abstracts Service, CiteFactor, CNKI Scholar, DOAJ, DRJI, EBSCO Discovery Service (EDS, Google Scholar, Index Copernicus, InfoBase Index, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  8. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databases:BASE, CAB Abstracts, CAS (Chemical Abstracts Service, CiteFactor, CNKI Scholar, DOAJ, DRJI, EBSCO Discovery Service (EDS, Google Scholar, Index Copernicus, InfoBase Index, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  9. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler


    Full Text Available Bu dergi, aşağıda listelenen veri tabanları tarafından taranmaktadır / This journal is indexed by the following abstracting and indexing databases:BASE, CAB Abstracts, CAS (Chemical Abstracts Service, CiteFactor, CNKI Scholar, DOAJ, DRJI, EBSCO Discovery Service (EDS, Google Scholar, Index Copernicus, InfoBase Index, JournalTOCs, OAJI, ResearchBib, Ulakbim TR Dizin (Mühendislik ve Temel Bilimler, WorldCat (OCLC, Zentralblatt MATH

  10. Inundation Mapping Tidal Surface - Mean Higher High Water (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are a derived product of the NOAA VDatum tool and they extend the tool's Mean Higher High Water (MHHW) tidal datum conversion inland beyond its original...

  11. Tidal variations in the Sundarbans estuarine system, India

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterjee, M.; Shankar, D.; Sen, G.K.; Sanyal, P.; Sundar, D.; Michael, G.S.; Chatterjee, A.; Amol, P.; Mukherjee, D.; Suprit, K.; Mukherjee, A.; Vijith, V.; Chatterjee, S.; Basu, A.; Das, M.; Chakraborti, S.; Kalla, A.; Misra, S.K.; Mukhopadhyay, S.; Mandal, G.; Sarkar, K.

    Situated in the eastern coastal state of West Bengal, the Sundarbans Estuarine System (SES) is India’s largest monsoonal, macro-tidal delta-front estuarine system. It comprises the southernmost part of the Indian portion of the Ganga...

  12. Sears Point Tidal Marsh Restoration Project: Phase II (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase II, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  13. Sears Point Tidal Marsh Restoration Project: Phase I (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase I project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  14. The structure of turbulence in a rapid tidal flow (United States)

    Milne, I. A.; Sharma, R. N.; Flay, R. G. J.


    The structure of turbulence in a rapid tidal flow is characterized through new observations of fundamental statistical properties at a site in the UK which has a simple geometry and sedate surface wave action. The mean flow at the Sound of Islay exceeded 2.5 m s-1 and the turbulent boundary layer occupied the majority of the water column, with an approximately logarithmic mean velocity profile identifiable close to the seabed. The anisotropic ratios, spectral scales and higher-order statistics of the turbulence generally agree well with values reported for two-dimensional open channels in the laboratory and other tidal channels, therefore providing further support for the application of universal models. The results of the study can assist in developing numerical models of turbulence in rapid tidal flows such as those proposed for tidal energy generation.

  15. Tidal Love numbers of membrane worlds: Europa, Titan, and Co

    CERN Document Server

    Beuthe, Mikael


    Under tidal forcing, icy satellites with subsurface oceans deform as if the surface were a membrane stretched around a fluid layer. `Membrane worlds' is thus a fitting name for these bodies and membrane theory provides the perfect toolbox to predict tidal effects. I describe here a new membrane approach to tidal perturbations based on the general theory of viscoelastic-gravitational deformations of spherically symmetric bodies. The massive membrane approach leads to explicit formulas for viscoelastic tidal Love numbers which are exact in the limit of zero crust thickness. The accuracy on $k_2$ and $h_2$ is better than one percent if the crust thickness is less than five percents of the surface radius, which is probably the case for Europa and Titan. The new approach allows for density differences between crust and ocean and correctly includes crust compressibility. This last feature makes it more accurate than the propagation matrix method. Membrane formulas factorize shallow and deep interior contributions, ...

  16. A Comprehensive Model for the Monoceros Tidal Stream

    National Research Council Canada - National Science Library

    Penarrubia, J; Martínez Delgado, D; Rix, H. W; Gomez-Flechoso, M. A; Munn, J; Newberg, H; Bell, E. F; Yanny, B; Zucker, D; Grebel, E. K


    ...., van den Bosch et al. 2004). The fossil records of these merging processes may be observable nowadays in the form of long tidal streams or large-scale stellar substructures around the parent spiral galaxies...

  17. Turbine Control of a Tidal and River Power Generator

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Wright, Alan; Gevorgian, Vahan; Donegan, James; Marnagh, Cian; McEntee, Jarlath


    As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded to include new types with promising future applications, such as river and tidal generation. The input variations to these types of resources are slower but also steadier than wind or solar generation. The level of water turbulent flow may vary from one place to another, however, the control algorithm can be adjusted to local environment. This paper describes the hydrokinetic aspects of river and tidal generation based on a river and tidal generator. Although the information given in this paper is not that of an exact generator deployed on site, the data used is representative of a typical river or tidal generator. In this paper, the hydrokinetic and associated electrical controller of the system were not included; however, the focus of this paper is on the hydrodynamic control.

  18. Turbine Control of a Tidal and River Power Generator: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Gevorgian, Vahan; Wright, Alan; Donegan, James; Marnagh, Cian; McEntee, Jarlath


    As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded to include new types with promising future applications, such as river and tidal generation. The input variations to these types of resources are slower but also steadier than wind or solar generation. The level of water turbulent flow may vary from one place to another, however, the control algorithm can be adjusted to local environment. This paper describes the hydrokinetic aspects of river and tidal generation based on a river and tidal generator. Although the information given in this paper is not that of an exact generator deployed on site, the data used is representative of a typical river or tidal generator. In this paper, the hydrokinetic and associated electrical controller of the system were not included; however, the focus of this paper is on the hydrodynamic control.

  19. Oregon Tidal Wetland vegetation and edaphic data 2010 - 2012 (United States)

    U.S. Environmental Protection Agency — Data includes edaphic and vegetation field data from four Oregon tidal wetlands. National Wetlands Inventory (NWI) classification: low marsh, high marsh, and...

  20. The structure of turbulence in a rapid tidal flow. (United States)

    Milne, I A; Sharma, R N; Flay, R G J


    The structure of turbulence in a rapid tidal flow is characterized through new observations of fundamental statistical properties at a site in the UK which has a simple geometry and sedate surface wave action. The mean flow at the Sound of Islay exceeded 2.5 m s-1 and the turbulent boundary layer occupied the majority of the water column, with an approximately logarithmic mean velocity profile identifiable close to the seabed. The anisotropic ratios, spectral scales and higher-order statistics of the turbulence generally agree well with values reported for two-dimensional open channels in the laboratory and other tidal channels, therefore providing further support for the application of universal models. The results of the study can assist in developing numerical models of turbulence in rapid tidal flows such as those proposed for tidal energy generation.

  1. Tidal Power Corporation annual report, 1987-1988

    Energy Technology Data Exchange (ETDEWEB)


    During Nova Scotia's Tidal Power Corporation activities in the year ending March 31, 1988, progress was made on solutions to some problems which are a prerequisite to large-scale tidal power development in the Bay of Fundy. Studies were conducted on fish mortality and methods of fish diversion such as the use of sound waves. The problem of retiming, or storage of energy when yielded by the tides and delivery to meet customer demands, was also investigated. The focus was on compressed air energy storage using underground caverns. Discussion was also held with US scientists to identify research needs relating to environmental impacts of a Fundy power plant. The 1986 drop in oil prices has reduced the apparent economic attractiveness of tidal power and development of a tidal power plant is not being advised at the present time. Financial statements of the Corporation are appended.

  2. A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation. (United States)

    Libros, R; Philips, C M; Wolfson, M R; Shaffer, T H


    Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.

  3. Tidal Marsh Vegetation of China Camp, San Pablo Bay, California


    Baye, Peter R.


    China Camp (Marin County, California) preserves extensive relict stands of salt marsh vegetation developed on a prehistoric salt marsh platform with a complex sinuous tidal creek network. The low salt marsh along tidal creeks supports extensive native stands of Pacific cordgrass (Spartina foliosa). The outer salt marsh accreted following hydraulic gold mining sedimentation. It consists of a wave-scarped pickleweed-dominated (Sarcocornia pacifica) high salt marsh terrace with a broad fringing ...

  4. Tidal Love numbers of a slowly spinning neutron star (United States)

    Pani, Paolo; Gualtieri, Leonardo; Ferrari, Valeria


    By extending our recent framework to describe the tidal deformations of a spinning compact object, we compute for the first time the tidal Love numbers of a spinning neutron star to linear order in the angular momentum. The spin of the object introduces couplings between electric and magnetic distortions, and new classes of spin-induced ("rotational") tidal Love numbers emerge. We focus on stationary tidal fields, which induce axisymmetric perturbations. We present the perturbation equations for both electric-led and magnetic-led rotational Love numbers for generic multipoles and explicitly solve them for various tabulated equations of state and for a tidal field with an electric (even parity) and magnetic (odd parity) component with ℓ=2 , 3, 4. For a binary system close to the merger, various components of the tidal field become relevant. In this case we find that an octupolar magnetic tidal field can significantly modify the mass quadrupole moment of a neutron star. Preliminary estimates, assuming a spin parameter χ ≈0.05 , show modifications ≳10 % relative to the static case, at an orbital distance of five stellar radii. Furthermore, the rotational Love numbers as functions of the moment of inertia are much more sensitive to the equation of state than in the static case, where approximate universal relations at the percent level exist. For a neutron-star binary approaching the merger, we estimate that the approximate universality of the induced mass quadrupole moment deteriorates from 1% in the static case to roughly 6% when χ ≈0.05 . Our results suggest that spin-tidal couplings can introduce important corrections to the gravitational waveforms of spinning neutron-star binaries approaching the merger.

  5. Monitoring Tidal Currents with a Towed ADCP System (United States)


    Monitoring tidal currents with a towed ADCP system Alexei Sentchev1 & Max Yaremchuk2 Received: 22 September 2015 /Accepted: 10 December 2015...English Channel) is measured during the var- ious stages of the tidal cycle with a low-cost towed Acoustic Doppler Current Profiler ( ADCP ) system for the...provided by the ADCP observations and their error statistics. Technically, the MARS model run provides the first guess (background) evo- lution of the

  6. Bedload transport in an inlet channel during a tidal cycle

    DEFF Research Database (Denmark)

    Ernstsen, V. B.; Becker, M.; Winter, C.


      Based on high-resolution swath bathymetry measurements at centimetre-scale precision conducted during a tidal cycle in a dune field in the Grådyb tidal inlet channel in the DanishWadden Sea, a simple tool to calculate bedload transport is presented. Bedload transport was related to simultaneous...... variations in grain-size composition of the mobilised sediment should be taken into account by sediment transport formulae....

  7. Classifications, sedimentary features and facies associations of tidal flats

    Directory of Open Access Journals (Sweden)

    Fan Daidu


    Full Text Available Significant progress has been achieved in the research of tide-dominated environments in the past two decades. These studies highlight both the importance and diversity of tidal flats in modern coastal environments. Based on their developing settings, tidal flats are subdivided into nine types, which are in turn grouped into sheltered or exposed spectrums according to the magnitude of exposure to waves. The ternary coastal classification model is revised with an embedded triangle to highlight non-open coast tidal flats as major second-order morphological elements to the first-order coastal environments including deltas, estuaries and lagoons. A new continuous spectrum of open coast depositional settings is proposed from muddy tidal flats of tide dominance with wave influence, through sandy tidal flats of mixed energy (tide-dominated, and tidal beaches of mixed energy (wave-dominated, to beaches of wave-dominance with tide influence. It is worth noting that no open coast setting is absolutely exempt from wave or tide influence. Three diagnostic criteria for the intertidal-flat deposits are proposed. Upon an upward-fining succession, (1 regular changes vertically from flaser bedding, through wavy bedding and to lenticular bedding are diagnostic of most of intertidal flats; (2 cyclical tidal rhythmites point to sheltered intertidal flats typically at the inner part of macrotidal estuaries; (3 rhythmic alternations of storm and tidal deposition are diagnostic of exposed intertidal flats, especially the open coast types. Intertidal-flat deposits are generally topped by saltmarsh deposits, but underlain by different subtidal successions, like thick subtidal channel-fills, sand-bar complexes (sheltered coastal settings, and upwards coarsening successions of subtidal flats or thick subtidal sand ridge/bar complexes (exposed coastal environments.

  8. Tidal Current Energy Resource Assessment Around Buton Island, Southeast Sulawesi, Indonesia


    Ribal, Agustinus; Amir, Amir Kamal; Toaha, Syamsuddin; Kusuma, Jeffry; Khaeruddin


    International Journal bereputasi An early stage of assessing tidal current energy resources is carried out in this present work. Tidal current power is estimated around Buton Island, Southeast Sulawesi province, Indonesia. Two-dimensional, depth-integrated of Advanced Circulation (ADCIRC) model has been used to simulate tidal elevation and barotropic tidal current around the island. Green???s function approach has been used to improve eight tidal constituents on the open boundary condition...

  9. Tidal characteristics near the Chinese Zhongshan Station in Prydz Bay, East Antarctica

    Directory of Open Access Journals (Sweden)

    Huang Jifeng


    Full Text Available A permanent tidal station was installed at the Chinese Zhongshan Station in Feb. 2010. Harmonic constants of 170 tidal constituents were obtained from harmonic analysis of the first year’s data. The results of the eight main constituents showed good agreement with those of two tidal models. Tidal characteristics, such as tide type, diurnal inequality, tidal range, and water levels were also analyzed.

  10. Atmospheric Bulges on Tidally-Locked Satellites (United States)

    Oza, Apurva V.; Johnson, Robert E.; Leblanc, Francois


    We use a simple analytic model to examine the spatial distribution of a volatile species in a surface-bounded atmosphere on a rotating object that is tidally-locked to its parent body. Spatial asymmetries in such atmospheres have recently been observed via ultraviolet auroral emissions from the exospheres of the icy satellites Europa and Ganymede. The Hubble Space Telescope observations indicate that these satellites host unique, surface-bounded O2 exospheres which bulge towards dusk. Using a simple 1-D mass conservation balance we examine the nature of the volatile source, the surface temperature profile, the spatial morphology of the loss process, and the adsorption and desorption properties of the surfaces to understand the spatial distribution of the surface-bounded atmosphere for a number of objects. Since the ballistic hop distances are much smaller than the satellite radii, we show that the observed asymmetries at Europa and Ganymede can be simply due to a strongly thermally-dependent source, although asymmetries in the plasma-induced loss could contribute. A key condition for these atmospheric bulges that are shifted towards dusk is the relationship between the rotation rate and the atmospheric loss rate.

  11. Stingray tidal stream energy device - phase 3

    Energy Technology Data Exchange (ETDEWEB)



    The 150 kW Stingray demonstrator was designed, built and installed by The Engineering Business (EB) in 2002, becoming the world's first full-scale tidal stream generator. The concept and technology are described in the reports from Phases 1 and 2 of the project. This report provides an overview of Phase 3 - the re-installation of Stingray in Yell Sound in the Shetland Isles between July and September 2003 for further testing at slack water and on the flood tide to confirm basic machine characteristics, develop the control strategy and to demonstrate performance and power collection through periods of continuous operation. The overall aim was to demonstrate that electricity could be generated at a potentially commercially viable unit energy cost; cost modelling indicated a future unit energy cost of 6.7 pence/kWh when 100 MW capacity had been installed. The report describes: project objectives, targets and activities; design and production; marine operations including installation and demobilisation; environmental monitoring and impact, including pre-installation and post-decommissioning surveys; stakeholder involvement; test results on machine characteristics, sensor performance, power cycle analysis, power collection, transmission performance and efficiency, current data analysis; validation of the mathematical model; the background to the economic model; cost modelling; and compliance with targets set by the Department of Trade and Industry (DTI).

  12. Simultaneous perturbation stochastic approximation for tidal models

    KAUST Repository

    Altaf, M.U.


    The Dutch continental shelf model (DCSM) is a shallow sea model of entire continental shelf which is used operationally in the Netherlands to forecast the storm surges in the North Sea. The forecasts are necessary to support the decision of the timely closure of the moveable storm surge barriers to protect the land. In this study, an automated model calibration method, simultaneous perturbation stochastic approximation (SPSA) is implemented for tidal calibration of the DCSM. The method uses objective function evaluations to obtain the gradient approximations. The gradient approximation for the central difference method uses only two objective function evaluation independent of the number of parameters being optimized. The calibration parameter in this study is the model bathymetry. A number of calibration experiments is performed. The effectiveness of the algorithm is evaluated in terms of the accuracy of the final results as well as the computational costs required to produce these results. In doing so, comparison is made with a traditional steepest descent method and also with a newly developed proper orthogonal decompositionbased calibration method. The main findings are: (1) The SPSA method gives comparable results to steepest descent method with little computational cost. (2) The SPSA method with little computational cost can be used to estimate large number of parameters.

  13. Tidal pumping facilitates dissimilatory nitrate reduction in intertidal marshes. (United States)

    Zheng, Yanling; Hou, Lijun; Liu, Min; Liu, Zhanfei; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Yu, Chendi; Wang, Rong; Jiang, Xiaofen


    Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium, remains unexplored in these habitats. Here, we use isotope-tracing and molecular approaches simultaneously to show that both nitrate-reduction activities and associated functional bacterial abundances are enhanced at the sediment-tidal water interface and at the tide-induced groundwater fluctuating layer. This pattern suggests that tidal pumping may sustain dissimilatory nitrate reduction in intertidal zones. The tidal effect is supported further by nutrient profiles, fluctuations in nitrogen components over flood-ebb tidal cycles, and tidal simulation experiments. This study demonstrates the importance of tides in regulating the dynamics of dissimilatory nitrate-reducing pathways and thus provides new insights into the biogeochemical cycles of nitrogen and other elements in intertidal marshes.

  14. The Conceptual Design of a Tidal Power Plant in Taiwan

    Directory of Open Access Journals (Sweden)

    Jia-Shiuan Tsai


    Full Text Available Located on the northwestern of Taiwan, the Matsu archipelago is near mainland China and comprises four islands: Nangan, Beigan, Juguang, and Dongyin. The population of Matsu totals 11,196 and is chiefly concentrated on Nangan and Beigan. From 1971 to 2000, Matsu built five oil-fired power plants with a total installed capacity of 47 MW. However, the emissions and noise generated by the oil-fired power plant has caused damage to Matsu’s environment, and the cost of fuel is high due to the long-distance shipping from Taiwan. Developing renewable energy in Matsu has therefore been a fervent topic for the Taiwan government, and tidal power is considered to be of the highest priority due to Matsu’s large tidal range (4.29 m in average and its semidiurnal tide. Moreover, the islands of Nangan and Beigan are composed of granite and have natural harbors, rendering them ideal places for coastal engineering of tidal power plants. This paper begins with a renewable energy reserves assessment in Matsu to determine the amount of tidal energy. Next, a tidal turbine type of the lowest cost is chosen, and then its dynamic characteristic, performance, and related design are analyzed. Finally, the coastal engineering condition was investigated, and a conceptual design for tidal power plant is proposed.

  15. Assessment of Kinetic Tidal Energy Resources Using SELFE

    Directory of Open Access Journals (Sweden)

    Manasa Ranjan Behera


    Full Text Available An investigation is carried out to study the theoretical tidal stream energy resource in the Singapore Strait to support the search for renewable energy in the effort to reduce the carbon footprints in the Southeast Asia. The tidal hydrodynamics in the Singapore Strait has been simulated using a Semi-implicit Eulerian-Lagrangian Finite-Element (SELFE model solving the 3D shallow water equations with Boussinesq approximations. Potential sites, with high tidal current (2.5 m/s and suitable for Tidal Energy Converter (TEC array installation to generate sustainable energy, have been identified. Further, various operational factors for installation of Tidal Energy Converters are considered before computing the theoretical power output for a typical TEC array. An approximate estimation of the possible theoretical power extraction from a TEC array shows an energy potential of up to 4.36% of the total energy demand of Singapore in 2011. Thus, the study suggests a detailed investigation of potential sites to quantify the total tidal stream energy potential in the Singapore Strait.

  16. Tidal Turbines’ Layout in a Stream with Asymmetry and Misalignment

    Directory of Open Access Journals (Sweden)

    Nicolas Guillou


    Full Text Available A refined assessment of tidal currents variability is a prerequisite for successful turbine deployment in the marine environment. However, the numerical evaluation of the tidal kinetic energy resource relies, most of the time, on integrated parameters, such as the averaged or maximum stream powers. Predictions from a high resolution three-dimensional model are exploited here to characterize the asymmetry and misalignment between the flood and ebb tidal currents in the “Raz de Sein”, a strait off western Brittany (France with strong potential for array development. A series of parameters is considered to assess resource variability and refine the cartography of local potential tidal stream energy sites. The strait is characterized by strong tidal flow divergence with currents’ asymmetry liable to vary output power by 60% over a tidal cycle. Pronounced misalignments over 20 ∘ are furthermore identified in a great part of energetic locations, and this may account for a deficit of the monthly averaged extractable energy by more than 12%. As sea space is limited for turbines, it is finally suggested to aggregate flood and ebb-dominant stream powers on both parts of the strait to output energy with reduced asymmetry.

  17. Performance of small-scale tidal power plants (United States)

    Fay, J. A.; Smachlo, M. A.


    Small-scale tidal power plants - having electric power between 1 and 100 MW, approximately - possess several attractive economic and environmental benefits. The dynamical behavior of such systems is calculated in terms of dimensionless variables and parameters, so that the size of the system is inconsequential (except for one parameter related to the slope of the walls of the tidal basin). Two measures of system performance are defined: capacity factor (ratio of average to rated power) and effectiveness (ratio of average to ideal tidal power). It was found that improving both parameters is mutually incompatible so that an economic analysis will determine the optimum values of the system design and performance parameters. The effects of variation of tidal range and basin shape were determined. Using typical variable flow properties of low-head hydroturbines, a favorable design head could be determined from the analysis. It was found that the change in the area of the intertidal zone relative to the surface area of the tidal pond is greater for small, as compared to large, systems, possibly leading to proportionately greater environmental effects. A comparison of the performance of several tidal power plant designs with the methodology of this paper showed generally good agreement with the dimensionless performance parameters and only a modest difference among them over several orders of magnitude in size of power plant.

  18. Estuary-wide genetic stock distribution and salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  19. The Effects of the Impedance of the Flow Source on the Design of Tidal Stream Generators (United States)

    Salter, S.


    The maximum performance of a wind turbine is set by the well-known Betz limit. If the designer of a wind turbine uses too fast a rotation, too large a blade chord or too high an angle of blade pitch, the air flow can take an easier path over or around the rotor. Most estimates of the tidal stream resource use equations borrowed from wind and would be reasonably accurate for a single unit. But water cannot flow through the seabed or over rotors which reach to the surface. If contra-rotating, vertical-axis turbines with a rectangular flow-window are placed close to one another and reach from the surface close to the seabed, the leakage path is blocked and they become more like turbines in a closed duct. Instead of an equation with area times velocity-cubed we should use the first power of volume flow rate though the rotor times the pressure difference across it. A long channel with a rough bed will already be losing lots of energy and will behave more like a high impedance flow. Attempts to block it with closely-packed turbines will increase the head across the turbines with only a small effect on flow rate. The same thing will occur if a close-packed line of turbines is built out to sea from a headland. It is necessary to understand the impedance of the flow source all the way out to mid-ocean. In deep seas where the current velocities at the seabed are too slow to disturb the ooze the friction coefficients will be similar to those of gloss paint, perhaps 0.0025. But the higher velocities in shallow water will remove ooze and quite large sediments leaving rough, bare rock and leading to higher friction-coefficients. Energy dissipation will be set by the higher friction coefficients and the cube of the higher velocities. The presence of turbines will reduce seabed losses and about one third of the present loss can be converted to electricity. The velocity reduction would be about 10%. In many sites the energy output will be far higher than the wind turbine equations

  20. Trophic relationships in tidal flat areas: To what extent are tidal flats dependent on imported food? (United States)

    Asmus, Harald; Asmus, Ragnhild M.

    In four intertidal areas of 'Königshafen' (island of Sylt, FRG), biomass and production of macrozoobenthos were measured monthly in 1980 and 1984. The areas were characterized by different macrofauna assemblages ( Nereis-Corophium belt, seagrass bed, Arenicola flat and mussel bed). Biomass and production of macrofauna were partitioned with regard to food preference of single species as well as to the food availability within their habitat. In the Nereis-Corophium belt, seagrass bed and the Arenicola flat, most of the secondary production of the macrofauna was formed by grazing animals. Secondary production of mussel beds was nearly 10 times higher than in the other three assemblages. The suspension feeder assemblage depended on planktonic food imported from outside the bay. Considering the secondary production of the total tidal flat area, suspension feeders dominated the other trophic groups, indicating a key position of this group relative to the other macrofaunal assemblages. Mussel beds regulate the seston input to other communities situated further landward. Because of this dominance of the suspension feeder group, the energy and material flow of the total tidal flat is strongly dependent on the seston input from the coastal waters of the North Sea or from other parts of the Wadden Sea.

  1. Geneviève Leguerrier | IDRC - International Development Research ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Geneviève Leguerrier is the Director of Finance and Administration. Geneviève held various managerial positions within IDRC's Finance and Administration division as well as its Grants Administration division. Prior to joining IDRC in 1998, she worked at the Office of the Auditor General. She has a Bachelor's degree in ...

  2. Naïve Bayes classification in R


    Zhang, Zhongheng


    Naïve Bayes classification is a kind of simple probabilistic classification methods based on Bayes’ theorem with the assumption of independence between features. The model is trained on training dataset to make predictions by predict() function. This article introduces two functions naiveBayes() and train() for the performance of Naïve Bayes classification.

  3. BProVe: Tool support for business process verification

    DEFF Research Database (Denmark)

    Corradini, Flavio; Fornari, Fabrizio; Polini, Andrea


    This demo introduces BProVe, a tool supporting automated verification of Business Process models. BProVe analysis is based on a formal operational semantics defined for the BPMN 2.0 modelling language, and is provided as a freely accessible service that uses open standard formats as input data...

  4. Morbidity Pattern among Under-five Children

    African Journals Online (AJOL)

    Morbidity Pattern among Under-five Children. A of Market Women in Ibadan. FO Omokhodion*,A Oyemade**,MKC Sridhar+. Summary. Omokhodion OF, Oyemade A, Sridhar MKC. Morbidity Pattern among Under-five. Children of Market Women in Ibadan. Nigerian journal of Paedialrz'rr 2003; 30:135. Background: The study ...

  5. Improvement of tidal breathing pattern analysis in children with asthma by on-line automatic data processing. (United States)

    van der Ent, C K; Brackel, H J; Mulder, P; Bogaard, J M


    The time taken to achieve peak tidal expiratory flow as a proportion of total expiratory time (t PTEF/t E) during tidal breathing (TB) is used as a parameter of airway obstruction in children with asthma. Curve selection bias is one of the most important limitations to the method. This study evaluates three curve selection methods, including a computer program, which on-line selects and analyses TB curves (Masterscreen Paediatric; Jaeger, Germany). TB analysis was performed in 26 children (aged 4-7 yrs) with asthma, before and after methacholine provocation and after subsequent bronchodilatation. Levels and stability of TB parameters derived from computer-selected, unselected and unbiased eye-selected curves were compared. t PTEF/t E ratios of the computer-selected curves agreed well with the unbiased eye-selected curves (limits of agreement -4.8 and +5.8%), but were significantly different from the ratios of unselected curves. Computer-derived t PTEF/t E ratios had the highest level of stability: the reliability coefficient of baseline measurements was 0.96 for computer selection, 0.84 for eye selection and 0.87 for no selection (reliability index = 1 at maximal stability). Tidal volume, respiratory rate, inspiratory and expiratory time were also assessed accurately by the computer program. The mean t PTEF/t E ratio (computer selection) dropped after methacholine provocation (from 30 +/- 9 to 22 +/- 9% at provocative dose at which forced expiratory volume in one second had dropped > or = 20% from baseline (FEV1-PD20 level), p < 0.001) and was restored after bronchodilation (30 +/- 6%; p < 0.001). We conclude that on-line computer analysis is preferable to no selection and to by-eye selection. The use of the program avoids curve selection bias and enhances the applicability of tidal breathing analysis as a measure of airflow obstruction in young children.

  6. Genç erkek ve bayanlarda ayakta ve yatar pozisyonlarda quadriceps açısının mukayesesi ve değerlendirilmesi


    Olcay, Ercan; Cetinus, Ercan; Mert, Murat; Kara, Ayhan


    Bu çalışmamızda genç populasyondaki bayan ve erkeklerde quadriceps açısı (Q açısı) değerlendirmeye alınmıştır. Q açısı 143 erkek ve 98 bayanda modifiye edilmiş ve goniometre kullanılarak hem ayakta, hem de yatar pozisyonlarda ölçüldü. Biz ortalama Q açısı değerlerini hesapladık ve kendi bulgularımızın sonuçlarını tartıştık.



    ÇEBİ BUĞDAYCI, Melike Özge


    İdarenin tesis edeceği işlem ve alacağı kararlarında genel idari usul kurallarına bağlı hareket etmesi, demokratik hukuk devletinin bir gereği ola- rak kabul görmektedir. Bu şekilde bireyin, kamu gücü ile donatılmış olan idare karşısında korunması ve idare ile yakınlaşması sağlanır. En önemli idari usul ilkelerinden biri olan dinlenilme hakkı gereğince de, hakkında tesis edilen ida- ri işlem ve kararlardan etkilenecek ilgililere, idare tarafından kendini savunma ve görüşünü açıklama imkânı ve...

  8. Tidal currents in the Yucatan Channel

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo Gonzalez, Fatima [Centro Universitario de la Costa, Universidad de Guadalajara, Guadalajara, Jalisco (Mexico); Ochoa, Jose; Candela, Julio; Badan, Antonio; Sheinbaum; Gonzalez Navarro, Juan Ignacio [Departamento de Oceanografia Fisica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California (Mexico)


    Currents data from a ten-month period at 197 measuring points covering all Yucatan Channel were processed by harmonic analysis to estimate tidal parameters for the O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} components. The highly detailed coverage confirms the known dominance for the O{sub 1} and K{sub 1} diurnal components, but also showed, for the first time, their intensification in the deep eastern margin of the channel where maximum amplitudes in main axis are 17 and 19 cm.s{sup -}1. The data also confirms weak semi-diurnal components, of which the most intense, M{sub 2} and S{sub 2}, have amplitudes only up to 2 cm.s{sup -}1. The tidal ellipses were elongated (i.e. with eccentricities close to one) in the NNW direction. The O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} contributions in transport variability through the channel have amplitudes of 11.7, 12.5, 1.2 and 1.0 Sv, all well determined above noise. [Spanish] Se presentan, a detalle sin precedente, las caracteristicas de las corrientes de marea O{sub 1}, K{sub 1}, M{sub 2} y S{sub 2} en el canal de Yucatan. Mapas de los parametros que definen las elipses, como son las amplitudes en los ejes principales, la orientacion, la fase y la razon-senal-ruido se obtienen, por el clasico analisis armonico en mediciones de 10 meses en duracion, en 197 puntos que cubren ampliamente un plano vertical del canal. En acuerdo con reportes anteriores, las senales diurnas O{sub 1} y K{sub 1} dominan, demostrandose aqui que sus amplitudes alcanzan, en la parte profunda y Este, 17 y 19 cm.s{sup -}1. El analisis tambien revela senales semidiurnas M{sub 2} y S{sub 2} muy debiles con amplitudes maximas de 2 y 1cm.s{sup -}1. Las elipses son muy alargadas (i.e. con excentricidad cercana a uno) y orientadas al nornoroeste. Los valores de la razon senal a ruido indican que los parametros de las dos constituyentes diurnas se encuentran bien determinados, mientras que las semidiurnas quedan muy contaminadas por el ruido. El rasgo mas

  9. Velocity anisotropy in tidally limited star clusters (United States)

    Tiongco, Maria A.; Vesperini, Enrico; Varri, Anna Lisa


    We explore the long-term evolution of the anisotropy in the velocity space of star clusters starting with different structural and kinematical properties. We show that the evolution of the radial anisotropy strength and its radial variation within a cluster contain distinct imprints of the cluster initial structural properties, dynamical history, and of the external tidal field of its host galaxy. Initially isotropic and compact clusters with small initial values of the ratio of the half-mass to Jacobi radius, rh/rJ, develop a strong radial anisotropy during their long-term dynamical evolution. Many clusters, if formed with small values of rh/rJ, should now be characterized by a significant radial anisotropy increasing with the distance from the cluster centre, reaching its maximum at a distance between 0.2 rJ and 0.4 rJ, and then becoming more isotropic or mildly tangentially anisotropic in the outermost regions. A similar radial variation of the anisotropy can also result from an early violent relaxation phase. In both cases, as a cluster continues its evolution and loses mass, the anisotropy eventually starts to decrease and the system evolves towards an isotropic velocity distribution. However, in order to completely erase the strong anisotropy developed by these compact systems during their evolution, they must be in the advanced stages of their evolution and lose a large fraction of their initial mass. Clusters that are initially isotropic and characterized by larger initial values of rh/rJ, on the other hand, never develop a significant radial anisotropy.

  10. Mobbing ve zdravotnické profesi


    Panáčková, Zdeňka


    Autor: Zde ka Paná ková Instituce: Ústav sociálního léka ství LF UK v Hradci Králové Odd lení ošet ovatelství Název práce: Mobbing ve zdravotnické profesi Vedoucí práce: Doc. PhDr.Jana Kutnohorská, CSc. Po et stran: 103 Po et p íloh: 4 Rok obhajoby: 2011 Key words: bullying, mobbing, mobber, victim, conflict, prevention, defense. Bachelor thesis explores bullying in the workplace, especially one of its forms - mobbing. The theoretical part focuses on clarifying the concept of mobbing. Charact...

  11. Kinestetik Zeka ve Beden Eğitimi


    KURU, Emin


    Her öğrencinin farklı türden zekaya sahip olduğunu göz önüne alarak onlara hedeflerine ulaşmaları konusunda yardımcı olabiliriz. Howard Gardner (1983) sekiz farklı zeka türünden bahsetmektedir ve bunlar: 1. Sözel dilsel zeka. 2. Mantıksal matematiksel zeka. 3. Müziksel ritmik zeka. 4. Görsel uzaysal zeka. 5. Bedensel kinestetik zeka. 6. Kişilerarası zeka. 7. İçsel zeka. 8. Doğal zeka. Bedensel kinestetik zekaya sahip olanlar belli bir yerde uzun süre kalamazlar. Biz bunlara hiperaktif d...

  12. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus


    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  13. Tidal networks: 2. Watershed delineation and comparative network morphology (United States)

    Rinaldo, Andrea; Fagherazzi, Sergio; Lanzoni, Stefano; Marani, Marco; Dietrich, William E.


    Through the new method for automatic extraction of a tidal network from topographic or bathymetric fields described in a companion paper [Fagherazzi et al., this issue], we analyze the morphology of aggregated patterns that we observe in nature in different tidal environments. Specifically, we define, on the basis of a hydrodynamic analysis, a procedure for watershed delineation and for the identification of the "divides" for every subnetwork and look at the resulting drainage density and its related scaling properties. From the systematic, large-scale plots of drainage density and channel width versus watershed area we address the issue of a possible geomorphic criterion that corresponds to the parts of the tidal landscape that are characterized by river-like features. We also analyze the relationship of total contributing tidal basin area to channel widths and to mainstream lengths (Hack's law). We study comparatively probability distributions of total drainage areas and of "botanical" mass (the area of the channelized landscape upstream of a given section) for tidal and fluvial patterns and find altered scaling features of tidal landforms that reflect the complex interactions of different mechanisms that shape their geometry. Simple geomorphic relationships of the types observed in the fluvial basin (e.g., power laws in the watershed area versus drainage density, mainstream length, or channel width relationships) do not hold throughout the range of scales investigated and are site-specific. We conclude that tidal networks unlike rivers exhibit great diversity in their geometrical and topological forms. This diversity is suggested to stem from the pronounced spatial gradients of landscape-forming flow rates and from the imprinting of several crossovers from competing dynamic processes.



    Dişbudak, Cem; Bozkulak, Serpil


    Kapitalizm kendisini tarihsel olarak sosyal haklar söylemi üzerine temellendirmiştir. Bu söylemin tarih içerisinde önemli ölçüde gerçekleştiği dönem ise yalnızca ‘altın çağ' olarak bilinen 1945-1975 arasıdır. 1970'lerin ortasındaki petrol krizi ile birlikte hem merkez hem de çevre ülkelerde sosyal haklarda önemli kesintiler oldu ve bu süreç neoliberal çağda hızlanarak devam etti. Bu dönem boyunca sosyal politikalar üst sınıfların ‘merhamet'ine indirgendi ve STK'lara havale edildi....

  15. Flow sitometri ve kullanım alanları

    Directory of Open Access Journals (Sweden)

    Martin Orlinov Kanev


    Full Text Available Hücrelerin biyokimyasal ve fiziksel özelliklerinin senelerdir primer mikroskop özellikleri kullanılarak saptanmasına karşılık, günümüzde flow sitometri tekniği kullanılmaya başlanmıştır. Flow sitometri, çeşitli hücrelerin bir süspansiyon halinde bir akış kanalı boyunca tek tek geçmesi ve bu sırada hücre büyüklüğü ve granülaritesine göre sınıflandırılması esasına dayanan bir teknik ve cihazdır. Bu cihaz ile hücrenin yüzey ve iç proteinleri, organelleri ve diğer bileşenleri analiz ve ayrımı, lazer ve elektronik teknolojisi kullanılarak büyüklük, granülarite ve floresans emisyonu esasına göre gerçekleştirilmektedir. Flow sitometri tekniğinin temelini iyi bilmemiz bu tekniği birçok patolojide kullanmamızı sağlayarak sonuçlarının standardizasyonunu ve tanı koydurucu değerini de arttıracaktır.

  16. Recruitment and retention of lung volume


    Lapinsky, Stephen E


    Both a reduction in tidal volume and alveolar recruitment may be necessary to prevent ventilator-induced lung injury in the management of patients with acute respiratory distress syndrome. The lung collapse associated with endotracheal suctioning produces hypoxaemia, but it also causes de-recruitment, potentially aggravating lung injury. A study conducted by Dyhr and colleagues demonstrates the benefit of lung recruitment manoeuvres after suctioning, which help to improve oxygenation and rest...

  17. Modified Saint-Venant equations for flow simulation in tidal rivers

    Directory of Open Access Journals (Sweden)

    Xiao-qin Zhang


    Full Text Available Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations (the SVN model are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal level was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton's second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers (the ISVN model was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.

  18. Modified Saint-Venant Equations for Flow Simulation in Tidal Rivers

    Directory of Open Access Journals (Sweden)

    Xiao-qin ZHANG


    Full Text Available Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations (the SVN model are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal level was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton’s second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers (the ISVN model was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.

  19. Analysing how plants in coastal wetlands respond to varying tidal regimes throughout their life cycles. (United States)

    Xie, Tian; Cui, Baoshan; Li, Shanze


    Important to conserve plant species in coastal wetlands throughout their life cycle. All life stages in these habitats are exposed to varying tidal cycles. It is necessary to investigate all life stages as to how they respond to varying tidal regimes. We examine three wetlands containing populations of an endangered halophyte species, each subjected to different tidal regimes: (1). wetlands completely closed to tidal cycles; (2). wetlands directly exposed to tidal cycles (3). wetlands exposed to a partially closed tidal regime. Our results showed that the most threatened stage varied between wetlands subjected to these varying tidal regimes. We hypothesis that populations of this species have adapted to these different tidal regimes. Such information is useful in developing management options for coastal wetlands and modifying future barriers restricting tidal flushing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. I bought a freezer - you´ve bought a freezer - they´ve bought a freezer


    Bublitz, Wolfram


    I bought a freezer - you´ve bought a freezer - they´ve bought a freezer : repetition as a text-building device. - In: Repetition in dialogue / ed. by Carla Bazzanella. - Tübingen : Niemeyer, 1996. - S. 16-28. - (Beiträge zur Dialogforschung ; 11)

  1. Ultraviolet and optical observations of tidal disruption events

    Directory of Open Access Journals (Sweden)

    Gezari S.


    Full Text Available Tidal disruption events are expected to produce a luminous flare of radiation from fallback accretion of tidally disrupted stellar debris onto the central supermassive black hole. The first convincing candidates for tidal disruption events were discovered in the soft X-rays: large-amplitude, luminous, extremely-soft X-ray flares from inactive galaxies in the ROSAT All-Sky survey. However, the sparsely sampled light curves and lack of multiwavelength observations for these candidates make it difficult to directly constrain the parameters of their events (e.g., Eddington ratio, mass of the black hole, type of star disrupted. Here I present a review of the recent progress made in studying tidal disruption events in detail from taking advantage of wide-field, multi-epoch observations of UV and optical surveys (GALEX, SDSS, PTF, Pan-STARRS1 to measure well-sampled light curves, trigger prompt multiwavelength follow-up observations, and measure rates. I conclude with the promising potential of the next generation of optical synoptic surveys, such as LSST, to probe black hole demographics with samples of thousands of tidal disruption events.

  2. Exploring Stellar Populations in the Tidal Tails of NGC3256 (United States)

    Rodruck, Michael; Konstantopoulos, Iraklis; Charlton, Jane C.


    Galaxy interactions can inject material into the intergalactic medium via violent gravitational dynamics, often visualized in tidal tails. The composition of these tails has remained a mystery, as previous studies have focused on detecting tidal features, rather than the composite material itself. With this in mind, we have developed an observing program using deep, multiband imaging to probe the chaotic regions of tidal tails in search for an underlying stellar population. NGC3256's Western and Eastern tidal tails serve as a case study for this new technique. Our results show median color values of u - g = 1.12 and r - i = 0.09 for the Western tail, and u - g = 1.29 and r - i = 0.21 for the Eastern tail, corresponding to ages of approximately 450 Myr and 900 Myr for the tails, respectively. A u - g color gradient is seen in the Western tail as well, running from 1.32 to 1.08 (~2000 Myr to 400 Myr), suggesting ages inside tidal tails can have significant variations.

  3. A numerical study of equilibrium states in tidal network morphodynamics (United States)

    Xu, Fan; Coco, Giovanni; Zhou, Zeng; Tao, Jianfeng; Zhang, Changkuan


    The long-term morphodynamic evolution of tidal networks on tidal flats is investigated using a two-dimensional numerical model. We explore the physical processes related to the development of the morphology and the presence of equilibrium configurations. Tidal networks are simulated over a rectangular domain representing a tidal platform, a different setting compared to estuaries (subject to riverine influence) and lagoons (offshore bars constricting the flow). In the early and middle phases of the tidal network evolution, large sediment patches with rhombus-like shape form and gradually migrate in the flood direction, even though the overall sediment flux is ebb-directed. A cross-section-averaged "equilibrium" state is asymptotically approached after about 500 years. The area and peak discharge of the lower flat cross-sections at year 500 approximately show a 1:1 relationship, which is in agreement with field observations. We also show that model results are consistent with the Q-A relationship (peak discharge Q versus cross-sectional area A), which is obtained under the assumption of a constant Chézy friction.

  4. A numerical study of equilibrium states in tidal network morphodynamics (United States)

    Xu, Fan; Coco, Giovanni; Zhou, Zeng; Tao, Jianfeng; Zhang, Changkuan


    The long-term morphodynamic evolution of tidal networks on tidal flats is investigated using a two-dimensional numerical model. We explore the physical processes related to the development of the morphology and the presence of equilibrium configurations. Tidal networks are simulated over a rectangular domain representing a tidal platform, a different setting compared to estuaries (subject to riverine influence) and lagoons (offshore bars constricting the flow). In the early and middle phases of the tidal network evolution, large sediment patches with rhombus-like shape form and gradually migrate in the flood direction, even though the overall sediment flux is ebb-directed. A cross-section-averaged "equilibrium" state is asymptotically approached after about 500 years. The area and peak discharge of the lower flat cross-sections at year 500 approximately show a 1:1 relationship, which is in agreement with field observations. We also show that model results are consistent with the Q-A relationship (peak discharge Q versus cross-sectional area A), which is obtained under the assumption of a constant Chézy friction.

  5. 3-D Simulation of Vertical-Axial Tidal Current Turbine

    Directory of Open Access Journals (Sweden)

    Zhiyang Zhang


    Full Text Available Vertical-axial tidal current turbine is the key for the energy converter, which has the advantages of simple structure, adaptability to flow and uncomplex convection device. It has become the hot point for research and application recently. At present, the study on the hydrodynamic performance of vertical-axial tidal current turbine is almost on 2-D numerical simulation, without the consideration of 3-D effect. CFD (Computational Fluid Dynamics method and blade optimal control technique are used to improve accuracy in the prediction of tidal current turbine hydrodynamic performance. Numerical simulation of vertical-axial tidal current turbine is validated. Fixed and variable deflection angle turbine are comparatively studied to analysis the influence of 3-D effect and the character of fluid field and pressure field. The method, put the plate on the end of blade, of reduce the energy loss caused by 3-D effect is proposed. The 3-D CFD numerical model of vertical-axial tidal current turbine hydrodynamic performance in this study may provide theoretical, methodical and technical reference for the optimal design of turbine.

  6. Long-Term Morphological Modeling of Barrier Island Tidal Inlets

    Directory of Open Access Journals (Sweden)

    Richard Styles


    Full Text Available The primary focus of this study is to apply a two-dimensional (2-D coupled flow-wave-sediment modeling system to simulate the development and growth of idealized barrier island tidal inlets. The idealized systems are drawn from nine U.S. coastal inlets representing Pacific Coast, Gulf Coast and Atlantic Coast geographical and climatological environments. A morphological factor is used to effectively model 100 years of inlet evolution and the resulting morphological state is gauged in terms of the driving hydrodynamic processes. Overall, the model performs within the range of established theoretically predicted inlet cross-sectional area. The model compares favorably to theoretical models of maximum inlet currents, which serve as a measure of inlet stability. Major morphological differences are linked to inlet geometry and tidal forcing. Narrower inlets develop channels that are more aligned with the inlet axis while wider inlets develop channels that appear as immature braided channel networks similar to tidal flats in regions with abundant sediment supply. Ebb shoals with strong tidal forcing extend further from shore and spread laterally, promoting multi-lobe development bisected by ebb shoal channels. Ebb shoals with moderate tidal forcing form crescent bars bracketing a single shore-normal channel. Longshore transport contributes to ebb shoal asymmetry and provides bed material to help maintain the sediment balance in the bay.

  7. Heartbeat stars, tidally excited oscillations and resonance locking (United States)

    Fuller, Jim


    Heartbeat stars are eccentric binary stars in short-period orbits whose light curves are shaped by tidal distortion, reflection and Doppler beaming. Some heartbeat stars exhibit tidally excited oscillations and present new opportunities for understanding the physics of tidal dissipation within stars. We present detailed methods to compute the forced amplitudes, frequencies and phases of tidally excited oscillations in eccentric binary systems. Our methods (i) factor out the equilibrium tide for easier comparison with observations, (ii) account for rotation using the traditional approximation, (iii) incorporate non-adiabatic effects to reliably compute surface luminosity perturbations, (iv) allow for spin-orbit misalignment and (v) correctly sum over contributions from many oscillation modes. We also discuss why tidally excited oscillations (TEOs) are more visible in hot stars with surface temperatures T ≳ 6500 K, and we derive some basic probability theory that can be used to compare models with data in a statistical manner. Application of this theory to heartbeat systems can be used to determine whether observed TEOs can be explained by chance resonances with stellar oscillation modes, or whether a resonance locking process is operating.

  8. Indicators of optimal lung volume during high-frequency oscillatory ventilation in infants. (United States)

    Tingay, David G; Mills, John F; Morley, Colin J; Pellicano, Anastasia; Dargaville, Peter A


    During high-frequency oscillatory ventilation, an understanding of the relationship between lung volume and lung mechanics may help clinicians better apply ventilation. The objectives of this study were: 1) to describe the relationship between lung volume and lung function parameters during mapping of the deflation limb of the pressure-volume relationship in infants receiving high-frequency oscillatory ventilation, and 2) to determine whether these parameters might be useful in targeting an optimal volume to apply ventilation. Observational physiological study. Tertiary neonatal intensive care unit in a pediatric hospital. Fifteen infants receiving high-frequency oscillatory ventilation and muscle relaxants. The deflation limb of the pressure-volume relationship was mapped in each infant, after recruitment to total lung capacity, using stepwise airway pressure decrements. Total lung capacity and closing volume were defined by oxygenation response. Lung volume (respiratory inductive plethysmography), oxygen saturation, transcutaneous carbon dioxide, and indicators of lung mechanics were recorded at each pressure. A distinct bell-shaped relationship between lung volume and carbon dioxide, minute ventilation, and tidal volume (both at airway opening and by inductive plethysmography) could be identified on the deflation limb, with an improvement of 21.6 mm Hg (CO2), 168 mL/sec (minute ventilation), 0.25 mL/kg (airway opening tidal volume), and 13.7% (plethysmography tidal volume) compared with total lung capacity levels. The mean (SD) optimal volumes and pressures for these parameters were significantly lower than total lung capacity, occurring at volumes between 38.6 (39.8)% and 62.8 (31.1)% of total lung capacity, and 28 (36.3)% and 41.3 (38.7)% of pressure at total lung capacity (p volumes that maintained the oxygenation benefit of recruitment. Transcutaneous carbon dioxide, tidal volume, and minute ventilation may assist in refining strategies to identify optimal

  9. Tidal Stream Generators, current state and potential opportunities for condition monitoring

    DEFF Research Database (Denmark)

    Kappatos, Vassilios; Georgoulas, George; Avdelidis, Nicolas


    Tidal power industry has made significant progress towards commercialization over the past decade. Significant investments from sector leaders, strong technical progress and positive media coverage have established the credibility of this specific renewable energy source. However, its progress......, an overview is given of the global tidal activity status (tidal energy market size and geography), the key industry activity and the regulations-standards related with tidal energy industry. Therefore, the main goal of this paper is to provide a bird’s view of the current status of the tidal power industry...... to serve as a roadmap for the academia regarding the real needs of the tidal power industry....

  10. Assessment of the climate change impacts on fecal coliform contamination in a tidal estuarine system. (United States)

    Liu, Wen-Cheng; Chan, Wen-Ting


    Climate change is one of the key factors affecting the future microbiological water quality in rivers and tidal estuaries. A coupled 3D hydrodynamic and fecal coliform transport model was developed and applied to the Danshuei River estuarine system for predicting the influences of climate change on microbiological water quality. The hydrodynamic and fecal coliform model was validated using observational salinity and fecal coliform distributions. According to the analyses of the statistical error, predictions of the salinity and the fecal coliform concentration from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict the fecal coliform contamination as a result of climate change, including the change of freshwater discharge and the sea level rise. We found that the reduction of freshwater discharge under climate change scenarios resulted in an increase in the fecal coliform concentration. The sea level rise would decrease fecal coliform distributions because both the water level and the water volume increased. A reduction in freshwater discharge has a negative impact on the fecal coliform concentration, whereas a rising sea level has a positive influence on the fecal coliform contamination. An appropriate strategy for the effective microbiological management in tidal estuaries is required to reveal the persistent trends of climate in the future.

  11. Linking human impacts within an estuary to ebb-tidal delta evolution (United States)

    Dallas, Kate L.; Barnard, Patrick L.


    San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.

  12. Differences in tidal breathing between infants with chronic lung diseases and healthy controls

    Directory of Open Access Journals (Sweden)

    Wilitzki S


    Full Text Available Abstract Background The diagnostic value of tidal breathing (TB measurements in infants is controversially discussed. The aim of this study was to investigate to what extent the breathing pattern of sleeping infants with chronic lung diseases (CLD differ from healthy controls with the same postconceptional age and to assess the predictive value of TB parameters. Methods In the age of 36–42 postconceptional weeks TB measurements were performed in 48 healthy newborns (median age and weight 7d, 3100 g and 48 infants with CLD (80d, 2465 g using the deadspace-free flow-through technique. Once the infants had adapted to the mask and were sleeping quietly and breathing regularly, 20–60 breathing cycles were evaluated. Beside the shape of the tidal breathing flow-volume loop (TBFVL 18 TB parameters were analyzed using ANOVA with Bonferroni correction. Receiver-operator characteristic (ROC curves were calculated to investigate the discriminative ability of TB parameters. Results The incidence of concave expiratory limbs in CLD infants was 31% and significantly higher compared to controls (2% (p Conclusion The breathing pattern of CLD infants differs significantly from that of healthy controls. Concave TBFVL and an increased RR measured during quiet sleep and under standardized conditions may indicate diminished respiratory functions in CLD infants whereas most of the commonly used TB parameters are poorly predictive.

  13. General Investigation of Tidal Inlets: Stability of Selected United States Tidal Inlets (United States)


    to determine the relationships that exist among the geometric and dynamic characterisa tics and the e n’. -onmen fac tocs that control these...73 5 50 Siletz, OR 7-39 to 2-76 4 51 Netarts, OR 7-53 to 7-73 4 Report Organizacion 8. Previous research on tidal inlet stability is summarized in Part...Relatinsh-i ps Among Time Variar.t Cha neteri tics Channel Indices R SC LC T W:L R 1 3 3 5 SC 0 3 0 3 LC 0 1 9 2 T 4 6 3 8 W: R 1 6 1 4 SC 0 1 2 3 LC 0 1 7 4

  14. Tidal freshwater wetland herbivory in Anacostia Park (United States)

    Krafft, Cairn; Hatfield, Jeff S.; Hammerschlag, Richard S.


    Herbivory has played a major role in dictating vegetation abundance and species composition at Kingman Marsh in Anacostia Park, Washington, D.C., since restoration of this tidal freshwater wetland was initiated in 2000. In June 2009 an herbivory study was established to document the impacts of resident Canada goose (Branta canadensis maxima) herbivory to vegetation at Kingman Marsh. Sixteen modules consisting of paired exclosed plots and unfenced control plots were constructed. Eight of the modules were installed in vegetated portions of the restoration site that had been protected over time by fencing, while the remaining eight modules were placed in portions of the site that had not been protected over time and were basically unvegetated at the start of the experiment. Since the experiment was designed to determine the impacts of herbivory by resident Canada geese as opposed to other herbivores, exclosure fencing was elevated 0.2 m to permit access by herbivores such as fish and turtles while excluding mature Canada geese. Repeated measures analysis of variance (ANOVA) was used to analyze the differences between paired exclosure and control plots for a number of variables including total vegetative cover. Differences in total vegetative cover were not significant for the baseline data collected in June. By contrast, two months after the old protective fencing was removed from the initially-vegetated areas to allow Canada geese access to the control plots, total vegetative cover had declined dramatically in the initially-vegetated control plots, and differences between paired exclosed and control plots were significant (P = 0.0026). No herbivory by Canada geese or other herbivores such as fish or turtles was observed in the exclosures. These results show that Canada goose herbivory has inflicted significant damage to the native wetland vegetation in the portions of Kingman Marsh that had been refenced and replanted. Significant differences in total vegetative

  15. Yerelden Evrensele Japon Anime ve Manga Sanatı


    TAŞ ALİCENAP, Çiğdem


    Anime ve manga kültürü Uzakdoğu çizgi roman sanatının yoğun üretimi, tarih, din, kültür ve felsefenin konulara yansıması ve Batı çizgi film ve çizgi romanlarından ayrılan farklı tarzlarıyla araştırılması ve öğrenilmesi gereken değerler içermektedir. Japonya’ da çizgi film sanatının Batı’ daki Disney gibi bir endüstrinin dışında bu denli özgün ve başarılı örnekleri elbette o sanatçıların yetiştiği kültürün, tarihin, sanatın ve felsefi değerlerin olduğu kadar eski...

  16. Engineering of Tidal Inlets and Morphologic Consequences (United States)


    Kraus and Lin (2002) attribute an increased rate of migration and tendency for closure of the San Bernard River Mouth, Texas, to a large volume of...Corpus Christi, TX, 106 p. Kraus, N.C., and Lin, L. 2002. Coastal processes study of the San Bernard River Mouth, Texas: Stability and...Engineer School. 1932. The fundamentals of seacoast jetties. U.S. Army, Fort Humphrey, VA, 43 p. Vila-Concejo, Ferreira, O., Morris, B.D., Matias , A

  17. The effect of caffeine on diaphragmatic activity and tival volume in preterm infants

    NARCIS (Netherlands)

    Kraaijenga, Juliette V.; Hutten, Gerard J.; de Jongh, Franciscus H.C.; van Kaam, Anton H.


    Objective To determine the effect of caffeine on diaphragmatic activity, tidal volume (Vt), and end-expiratory lung volume (EELV) in preterm infants. Study design Using transcutaneous electromyography of the diaphragm (dEMG), we measured diaphragmatic activity from 30 minutes before (baseline) to 3

  18. Tidal and residual currents in the Bransfield Strait, Antarctica

    Directory of Open Access Journals (Sweden)

    O. López

    Full Text Available During the 1992-1993 oceanographic cruise of the Spanish R/V Hespérides, recording equipment was deployed in the Bransfield Strait. Six Aanderaa RCM7 current meters and three Aanderaa WLR7 tide gauges were successfully recovered after an operation period of 2.5 months. Relevant features of the time series obtained are presented and discussed in this paper. The emphasis is placed on the tidal character of the currents and the relative importance of tidal flow in the general hydrodynamics of the strait. For these purposes a dense grid of hydrographic stations, completed during the BIOANTAR 93 cruise, is used. Preliminary geostrophic calculations relative to a 400 m depth, yield current velocities of around 0.20 m s-1 in the study area, whereas the magnitude of tidal currents is seen to be 0.30-0.40 m s-1.

  19. Diurnal tidal variability in the upper mesosphere and lower thermosphere

    Directory of Open Access Journals (Sweden)

    M. E. Hagan


    Full Text Available We explore tropospheric latent heat release as a source of variability of the diurnal tide in the mesosphere and lower thermosphere (MLT in two ways. First, we present analyses of the UARS WINDII horizontal wind data, which reveal signatures of nonmigrating tidal effects as large as 25 m/s during both vernal equinox and boreal winter. These effects are of greater relative importance during the latter season. Complementary global-scale wave model (GSWM results which account for a tropospheric latent heat source generally underestimate the observed nonmigrating tidal effects but capture the seasonal variability that is observed. Second, we pursue a new parameterization scheme to investigate seasonal variability of the migrating diurnal tidal component of the latent heat source with GSWM. These results confirm previously reported seasonal trends, but suggest that the MLT effects may be as much as an order of magnitude larger than earlier predictions.

  20. Comparison between the theoretical and observed tidal gravimetric factors (United States)

    Dehant, V.; Ducarme, B.


    At present there is a discrepancy of ˜ 1.5% between the Wahr's gravimetric factor and the observed one. The aim of this paper is to explain a part of this discrepancy. To compare correctly the theory and the observations, it is necessary to adopt a different definition of the tidal gravimetric factor δ. A new theoretical value is then computed at each tidal frequency, for an elliptical uniformly rotating Earth model. From the ICET data bank, we deduce an experimental model for five tidal waves by regression between all the observations currently available and the function of the latitude which enter in the theoretical form of δ. The latitude dependent part fits the theory and the discrepancy on the constant part is reduced by a factor of two. The remaining gap is 0.5% for O1, 0.4% for P1, 0.8% for K1 and 0.8% for M2.

  1. Stellar dynamics and tidal disruption events in galactic nuclei

    Directory of Open Access Journals (Sweden)

    Alexander T.


    Full Text Available The disruption of a star by the tidal field of a massive black hole is the final outcome of a chain of complex dynamical processes in the host galaxy. I introduce the “loss cone problem”, and describe the many theoretical and numerical challenges on the path of solving it. I review various dynamical channels by which stars can be supplied to a massive black hole, and the relevant dynamical relaxation/randomization mechanisms. I briefly mention some “exotic” tidal disruption scenarios, and conclude by discussing new dynamical results that are changing our understanding of dynamics near a massive black hole, and may well be relevant for tidal disruption dynamics.

  2. Tidal Movement of Nioghalvfjerdsfjorden Glacier, Northeast Greenland: Observations and Modelling

    DEFF Research Database (Denmark)

    Reeh, Niels; Mayer, C.; Olesen, O. B.


    . The observations show that the main part of the glacier tongue responds as a freely floating plate to the phase and amplitude of the local tide in the sea. However, kilometre-wide flexure zones exist along the marginal and upstream grounding lines. Attempts to model the observed tidal deflection and tilt patterns...... in the flexure zone by elastic-beam theory are unsuccessful, in contrast to previous findings by other investigators. The strongest disagreement between our measurements and results derived from elastic-beam theory is a significant variation of the phase of the tidal records with distance from the grounding line...... (most clearly displayed by the tilt records). We suggest that the viscous properties of glacier ice must be taken into account, and consequently that a viscoelastic-beam model must be used to adequately describe tidal bending of floating glaciers....

  3. Using Tidal Tails to Probe Dark Matter Halos (United States)

    Mihos, Chris; Dubinski, John; Hernquist, Lars


    We present a series of numerical simulations of merging galaxies to explore the effect of differing halo mass distributions on the morphology of tidal tails. We employ composite disk/bulge/halo galaxy models which span a range of halo properties from low mass, compact halos to very massive, extended halos, and possess identically flat rotation curves inside a few disk scale lengths. These merger experiments are performed with a range of impact parameters, inclinations and mass ratios for the galaxies as well. Our simulations indicate that even under the most favorable conditions, galaxies with extended dark matter halos produce very anemic tidal tails when merging. In light of several observed mergers which sport prominent tidal tails --- e.g., NGC 7252, NGC 4038/39 (``The Antennae"), NGC 4676, and most spectacularly IRAS 19254-7245 (``The Superantennae") --- our results suggest that galaxy halos may be significantly more compact and less massive than expected in Omega =1 cosmological scenarios.

  4. The gravitational self-interaction of the Earth's tidal bulge (United States)

    Norsen, Travis; Dreese, Mackenzie; West, Christopher


    According to a standard, idealized analysis, the Moon would produce a 54 cm equilibrium tidal bulge in the Earth's oceans. This analysis omits many factors (beyond the scope of the simple idealized model) that dramatically influence the actual height and timing of the tides at different locations, but it is nevertheless an important foundation for more detailed studies. Here, we show that the standard analysis also omits another factor—the gravitational interaction of the tidal bulge with itself—which is entirely compatible with the simple, idealized equilibrium model and which produces a surprisingly non-trivial correction to the predicted size of the tidal bulge. Our analysis uses ideas and techniques that are familiar from electrostatics, and should thus be of interest to teachers and students of undergraduate E&M, Classical Mechanics (and/or other courses that cover the tides), and geophysics courses that cover the closely related topic of Earth's equatorial bulge.

  5. Tidal fluctuations influence E. coli concentrations in urban estuaries. (United States)

    Jovanovic, Dusan; Coleman, Rhys; Deletic, Ana; McCarthy, David T


    This study investigated the influence of water level and velocity on Escherichia coli levels over multiple tidal cycles in an urban microtidal estuary in Melbourne, Australia. Over 3,500 E. coli samples and high resolution water level and velocity measurements from two locations within the estuary were used for the analysis. E. coli negatively correlated with water level in the upper estuary which was proposed to be linked to increased resuspension of estuarine sediments during low tide. No relationship was found in the lower estuary, likely due to wet weather inputs dwarfing subtler tidal-related processes. Removal of wet weather data enabled significant relationships to emerge in the lower estuary: 1) positive with water level (when a 9-h shift applied corresponding to the phase shift between water levels and velocities) and; 2) positive with velocity (no shift applied). This supports a link between increased E. coli levels and tidal-related resuspension. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Diurnal tidal variability in the upper mesosphere and lower thermosphere

    Directory of Open Access Journals (Sweden)

    M. E. Hagan

    Full Text Available We explore tropospheric latent heat release as a source of variability of the diurnal tide in the mesosphere and lower thermosphere (MLT in two ways. First, we present analyses of the UARS WINDII horizontal wind data, which reveal signatures of nonmigrating tidal effects as large as 25 m/s during both vernal equinox and boreal winter. These effects are of greater relative importance during the latter season. Complementary global-scale wave model (GSWM results which account for a tropospheric latent heat source generally underestimate the observed nonmigrating tidal effects but capture the seasonal variability that is observed. Second, we pursue a new parameterization scheme to investigate seasonal variability of the migrating diurnal tidal component of the latent heat source with GSWM. These results confirm previously reported seasonal trends, but suggest that the MLT effects may be as much as an order of magnitude larger than earlier predictions.

  7. Characterising the spatial variability of the tidal stream energy resource from floating turbines (United States)

    Ward, Sophie; Neill, Simon; Robins, Peter


    The shelf seas, in particular the northwest European shelf seas surrounding the UK, contain significant tidal power potential. Tidal stream energy is both predictable and reliable providing that sites are well-selected based upon the hydrodynamic regime and the device specifics. In this high resolution three-dimensional tidal modelling study, we investigate how the tidal stream resource around the Welsh coast (UK) varies with water depth and location, with particular focus on the Pembrokeshire region. The potential extractable energy for a floating tidal stream energy converter is compared with that for a bottom-fixed device, highlighting the need to vary the resource characterisation criteria based on device specifics. We demonstrate how small variations in the tidal current speeds - with hub depth or due to tidal asymmetry - can lead to substantial variations in potential power output. Further, the results indicate that power generation from floating tidal energy converters will be more significantly influenced by tidal elevations in regions characterised by a lower tidal range (more progressive waves) than regions that experience a high tidal range (standing waves). As numerical modelling capacity improves and tidal stream energy converter technologies develop, ongoing improved quantification of the tidal resource is needed, as well as consideration of the possible feedbacks of the devices and energy extraction on the hydrodynamic regime and the surrounding area.

  8. Propagation of tidal waves up in Yangtze Estuary during the dry season (United States)

    Lu, Sheng; Tong, Chaofeng; Lee, Dong-Young; Zheng, Jinhai; Shen, Jian; Zhang, Wei; Yan, Yixin


    Tide is one of the most important hydrodynamic driving forces and has unique features in the Yangtze Estuary (YE) due to the complex geometry of third-order bifurcations and four outlets. This paper characterizes the tidal oscillations, tidal dampening, tidal asymmetry, and tidal wave propagation, which provides insights into the response of the estuary to tides during the dry season. The structural components of tidal oscillations are initially attained by tidal analysis. The increasingly richer spectrum inside the estuary shows an energy transfer corresponding to the generation and development of nonlinear overtides and compound tides. A 2-D numerical model is further set up to reproduce tidal dynamics in the estuary. The results show that the estuary is a strongly dissipative estuary with a strong nonlinear phenomenon. Three amplifications are presented in the evolution process of tidal ranges due to the channel convergence. Tidal asymmetry is spatiotemporally characterized by the M4/M2 amplitude ratio, the 2M2-M4 phase difference, and the flood-ebb duration-asymmetry parameter, and the estuary tends to be flood-dominant. There exists mimic standing waves with the phase difference of the horizontal and vertical tide close to 90° when tidal wave propagates into the estuary, especially during the neap tide. In addition, the differences in tidal distortion, tidal ranges, and tidal waves along the two routes in the South Branch (S-B) suggest the branched system behaves differently from a single system.

  9. Breakdown of Hydrostatic Assumption in Tidal Channel with Scour Holes

    Directory of Open Access Journals (Sweden)

    Chunyan Li


    Full Text Available Hydrostatic condition is a common assumption in tidal and subtidal motions in oceans and estuaries.. Theories with this assumption have been largely successful. However, there is no definite criteria separating the hydrostatic from the non-hydrostatic regimes in real applications because real problems often times have multiple scales. With increased refinement of high resolution numerical models encompassing smaller and smaller spatial scales, the need for non-hydrostatic models is increasing. To evaluate the vertical motion over bathymetric changes in tidal channels and assess the validity of the hydrostatic approximation, we conducted observations using a vessel-based acoustic Doppler current profiler (ADCP. Observations were made along a straight channel 18 times over two scour holes of 25 m deep, separated by 330 m, in and out of an otherwise flat 8 m deep tidal pass leading to the Lake Pontchartrain over a time period of 8 hours covering part of the diurnal tidal cycle. Out of the 18 passages over the scour holes, 11 of them showed strong upwelling and downwelling which resulted in the breakdown of hydrostatic condition. The maximum observed vertical velocity was ~ 0.35 m/s, a high value in a tidal channel, and the estimated vertical acceleration reached a high value of 1.76×10-2 m/s2. Analysis demonstrated that the barotropic non-hydrostatic acceleration was dominant. The cause of the non-hydrostatic flow was the that over steep slopes. This demonstrates that in such a system, the bathymetric variation can lead to the breakdown of hydrostatic conditions. Models with hydrostatic restrictions will not be able to correctly capture the dynamics in such a system with significant bathymetric variations particularly during strong tidal currents.

  10. Tidal circulation and energy dissipation in a shallow, sinuous estuary (United States)

    Seim, Harvey; Blanton, Jackson; Elston, Susan


    The tidal dynamics in a pristine, mesotidal (>2 m range), marsh-dominated estuary are examined using moored and moving vessel field observations. Analysis focuses on the structure of the M 2 tide that accounts for approximately 80% of the observed tidal energy, and indicates a transition in character from a near standing wave on the continental shelf to a more progressive wave within the estuary. A slight maximum in water level (WL) occurs in the estuary 10-20 km from the mouth. M 2 WL amplitude decreases at 0.015 m/km landward of this point, implying head of tide approximately 75 km from the mouth. In contrast, tidal currents in the main channel 25 km inland are twice those at the estuary mouth. Analysis suggests the tidal character is consistent with a strongly convergent estuarine geometry controlling the tidal response in the estuary. First harmonic ( M 4) current amplitude follows the M 2 WL distribution, peaking at mid-estuary, whereas M 4 WL is greatest farther inland. The major axis current amplitude is strongly influenced by local bathymetry and topography. On most bends a momentum core shifts from the inside to outside of the bend moving seaward, similar to that seen in unidirectional river flow but with point bars shifted seaward of the bends. Dissipation rate estimates, based on changes in energy flux, are 0.18-1.65 W m-2 or 40-175 μW kg-1. A strong (0.1 m/s), depth-averaged residual flow is produced at the bends, which resembles flow around headlands, forming counter-rotating eddies that meet at the apex of the bends. A large sub-basin in the estuary exhibits remarkably different tidal characteristics and may be resonant at a harmonic of the M 2 tide.

  11. Tidal Love numbers of membrane worlds: Europa, Titan, and Co. (United States)

    Beuthe, Mikael


    Under tidal forcing, icy satellites with subsurface oceans deform as if the surface were a membrane stretched around a fluid layer. 'Membrane worlds' is thus a fitting name for these bodies and membrane theory provides the perfect toolbox to predict tidal effects. I describe here a new membrane approach to tidal perturbations based on the general theory of viscoelastic-gravitational deformations of spherically symmetric bodies. The massive membrane approach leads to explicit formulas for viscoelastic tidal Love numbers which are exact in the limit of zero crust thickness. Formulas for load Love numbers come as a bonus. The accuracy on k2 and h2 is better than one percent if the crust thickness is less than five percents of the surface radius, which is probably the case for Europa and Titan. The new approach allows for density differences between crust and ocean and correctly includes crust compressibility. This last feature makes it more accurate than the incompressible propagator matrix method. Membrane formulas factorize shallow and deep interior contributions, the latter affecting Love numbers mainly through density stratification. I show that a screening effect explains why ocean stratification typically increases Love numbers instead of reducing them. For Titan, a thin and dense liquid layer at the bottom of a light ocean can raise k2 by more than ten percents. The membrane approach can also deal with dynamical tides in a non-rotating body. I show that a dynamical resonance significantly decreases the tilt factor and may thus lead to underestimating Europa's crust thickness. Finally, the dynamical resonance increases tidal deformations and tidal heating in the crust if the ocean thickness is of the order of a few hundred meters.

  12. Structural and tidal models of Titan and inferences on cryovolcanism (United States)

    Sohl, F.; Solomonidou, A.; Wagner, F. W.; Coustenis, A.; Hussmann, H.; Schulze-Makuch, D.


    Titan, Saturn's largest satellite, is subject to solid body tides exerted by Saturn on the timescale of its orbital period. The tide-induced internal redistribution of mass results in tidal stress variations, which could play a major role for Titan's geologic surface record. We construct models of Titan's interior that are consistent with the satellite's mean density, polar moment-of-inertia factor, obliquity, and tidal potential Love number k2 as derived from Cassini observations of Titan's low-degree gravity field and rotational state. In the presence of a global liquid reservoir, the tidal gravity field is found to be consistent with a subsurface water-ammonia ocean more than 180 km thick and overlain by an outer ice shell of less than 110 km thickness. The model calculations suggest comparatively low ocean ammonia contents of less than 5 wt % and ocean temperatures in excess of 255 K, i.e., higher than previously thought, thereby substantially increasing Titan's potential for habitable locations. The calculated diurnal tidal stresses at Titan's surface amount to 20 kPa, almost comparable to those expected at Enceladus and Europa. Tidal shear stresses are concentrated in the polar areas, while tensile stresses predominate in the near-equatorial, midlatitude areas of the sub- and anti-Saturnian hemispheres. The characteristic pattern of maximum diurnal tidal stresses is largely compliant with the distribution of active regions such as cryovolcanic candidate areas. The latter could be important for Titan's habitability since those may provide possible pathways for liquid water-ammonia outbursts on the surface and the release of methane in the satellite's atmosphere.

  13. Tidal stream energy in the Bay of Fundy

    Energy Technology Data Exchange (ETDEWEB)

    Hagerman, G. [Virginia Tech Advanced Research Inst., VA (United States)


    The Electric Power Research Institute (EPRI) is now exploring tidal in-stream energy conversion (TISEC) as a future energy supply option in collaboration with Nova Scotia Power Inc. (NSPI). In addition to providing a power density higher than wind and solar energy, tidal power provides the same benefits as other indigenous renewable energy options. NSPI owns and operates the only tidal power plant in North America, and its renewable portfolio standard requires it to meet targets with commercial TISEC projects in 2015-2020. This presentation outlined plans for a tidal energy project to be located in the Minas Passage area in the Bay of Fundy. An outline of earth-moon-sun tidal forces was provided, as well as details of estuary influences and harmonic constants. The DFO WebTide prediction model was used to assess the suitability of the site. Turbine output over a full range of tidal stream velocities was assessed. Various conversion technologies were simulated. Results indicated that the passage is large enough to provide an average of 120 MW using monopile-based technology, as well as an average of 980 MW in deep water using submerged technology. Physical resources were estimated at 1010 MW per year. Environmental extraction limits are 15 per cent of physical resource, meaning that average extraction will be limited to 150 MW. Fully submersible solutions were investigated. Cost estimations were provided. It was concluded that TISEC promises to be one of the most environmentally benign energy supply options available in the region. Research is needed to examine the impact of ice and offshore procedures to raise and lower submerged units for inspection and maintenance. Numerical modelling of turbine array effects on near-field and far-field circulation are also needed. refs., tabs., figs.


    Directory of Open Access Journals (Sweden)



    Full Text Available CONTINUITY EDITINGAbstract: As all filmmakers would know, film production is requires three steps. Pre-production, production and post-production (including editing. Although these steps seem detached, they are interrelated. It is impossible for a director to make his plans by avoiding editing which makes editing also a part of pre-production. When we talk about editing, compositional adjustment of two neighbor frames is the main point because it affects directly the viewer. By avoiding jump-cuts the director cannot reach the viewers, which also mean the emotional affect cannot be created. Editing which is called the invisible art, will look more successful if it’s not noticed: Whether it manipulates the viewer or keeps away from that manipulation. Keywords: Editing, Montage, Post-Production, Video. GÖRÜNTÜ KURGUSU VE DEVAMLILIKÖzet: Bilindiği gibi film yapımı, ister film, ister video malzemesi kullanılsın üç aşamadan oluşur. Ön-yapım, yapım, ve son-yapım (bu aşama çekilen filmin kurgulanmasını da içermektedir. Her ne kadar bir film çekimi bu üç farklı aşamadan oluşsa da, bu aşamalar pratikte iç içe geçmiş bir şekildedir. Bir yönetmenin filmini planlarken kurgu aşamasını öngörmemesi oldukça büyük bir eksiklik olacaktır ki, bu durum kurgunun planlanmasını ön-yapım aşamasının parçası haline getirir. Kurgu söz konusu olduğunda arka arkaya gelen iki komşu çerçevenin birbirine uyacak şekilde çekimi, yönetmenin izleyicisi ile buluşup buluşamaması durumunu ortaya çıkarır. Görünmeyen sanat denen, kurgu fark edilmediği oranda başarılı olacaktır. İster izleyiciyi yönlendiren bir eğilime sahip olsun isterse bu yönlendirmeden uzak durmayı amaçlasın.

  15. Tidal breathing parameters measured using structured light plethysmography in healthy children and those with asthma before and after bronchodilator. (United States)

    Hmeidi, Hamzah; Motamedi-Fakhr, Shayan; Chadwick, Edward; Gilchrist, Francis J; Lenney, Warren; Iles, Richard; Wilson, Rachel C; Alexander, John


    Structured light plethysmography (SLP) is a light-based, noncontact technique that measures tidal breathing by monitoring displacements of the thoracoabdominal (TA) wall. We used SLP to measure tidal breathing parameters and their within-subject variability (v) in 30 children aged 7-16 years with asthma and abnormal spirometry (forced expiratory volume in 1 sec [FEV1] <80% predicted) during a routine clinic appointment. As part of standard care, the reversibility of airway obstruction was assessed by repeating spirometry after administration of an inhaled bronchodilator. In this study, SLP was performed before and after bronchodilator administration, and also once in 41 age-matched controls. In the asthma group, there was a significant increase in spirometry-assessed mean FEV1 after administration of bronchodilator. Of all measured tidal breathing parameters, the most informative was the inspiratory to expiratory TA displacement ratio (IE50SLP, calculated as TIF50SLP/TEF50SLP, where TIF50SLP is tidal inspiratory TA displacement rate at 50% of inspiratory displacement and TEF50SLP is tidal expiratory TA displacement rate at 50% of expiratory displacement). Median (m) IE50SLP and its variability (vIE50SLP) were both higher in children with asthma (prebronchodilator) compared with healthy children (mIE50SLP: 1.53 vs. 1.22, P < 0.001; vIE50SLP: 0.63 vs. 0.47, P < 0.001). After administration of bronchodilators to the asthma group, mIE50SLP decreased from 1.53 to 1.45 (P = 0.01) and vIE50SLP decreased from 0.63 to 0.60 (P = 0.04). SLP-measured tidal breathing parameters could differentiate between children with and without asthma and indicate a response to bronchodilator. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  16. Periodicity in stem growth and litterfall in tidal freshwater forested wetlands: influence of salinity and drought on nitrogen recycling (United States)

    Cormier, Nicole; Krauss, Ken W.; Conner, William H.


    Many tidally influenced freshwater forested wetlands (tidal swamps) along the south Atlantic coast of the USA are currently undergoing dieback and decline. Salinity often drives conversion of tidal swamps to marsh, especially under conditions of regional drought. During this change, alterations in nitrogen (N) uptake from dominant vegetation or timing of N recycling from the canopy during annual litter senescence may help to facilitate marsh encroachment by providing for greater bioavailable N with small increases in salinity. To monitor these changes along with shifts in stand productivity, we established sites along two tidal swamp landscape transects on the lower reaches of the Waccamaw River (South Carolina) and Savannah River (Georgia) representing freshwater (≤0.1 psu), low oligohaline (1.1–1.6 psu), and high oligohaline (2.6–4.1 psu) stands; the latter stands have active marsh encroachment. Aboveground tree productivity was monitored on all sites through monthly litterfall collection and dendrometer band measurements from 2005 to 2009. Litterfall samples were pooled by season and analyzed for total N and carbon (C). On average between the two rivers, freshwater, low oligohaline, and high oligohaline tidal swamps returned 8,126, 3,831, and 1,471 mg N m−2 year−1, respectively, to the forest floor through litterfall, with differences related to total litterfall volume rather than foliar N concentrations. High oligohaline sites were most inconsistent in patterns of foliar N concentrations and N loading from the canopy. Leaf N content generally decreased and foliar C/N generally increased with salinization (excepting one site), with all sites being fairly inefficient in resorbing N from leaves prior to senescence. Stands with higher salinity also had greater flood frequency and duration, lower basal area increments, lower tree densities, higher numbers of dead or dying trees, and much reduced leaf litter fall (103 vs. 624 g m−2 year−1) over the

  17. Accretion processes in magnetically and tidally perturbed Schwarzschild black holes

    CERN Document Server

    Kovács, Zoltán; Vasúth, Mátyás


    We study the accretion process in the region of the Preston-Poisson space-time describing a Schwarzschild black hole perturbed by asymptotically uniform magnetic field and axisymmetric tidal structures. We find that the accretion disk shrinks and the marginally stable orbit shifts towards the black hole with the perturbation. The radiation intensity of the accretion disk increases, while the radius where radiation is maximal remains unchanged. The spectrum is blue-shifted. Finally, the conversion efficiency of accreting mass into radiation is decreased by both the magnetic and the tidal perturbations.

  18. Relativistic tidal heating of Hamiltonian quasi-local boundary expressions

    CERN Document Server

    So, Lau Loi


    Purdue and Favata calculate the tidal heating used certain classical pseudotensors. Booth and Creighton employed the quasi-local mass formalism of Brown and York to demonstrate the same subject. All of them give the result matched with the Newtonian theory. Here we present another Hamiltonian quasi-local boundary expressions and all give the same desired value. This indicates that the tidal heating is unique as Thorne predicted. Moreover, we discovered that the pseudo-tensor method and quasi-local method are fundamentally different.

  19. Production systems and energy potential of tidal energy

    Directory of Open Access Journals (Sweden)

    Julián Rodrigo Quintero-González


    Full Text Available This article discusses the concept of tidal power and distinguishes the types of systems to exploitation the tidal energy; the same way; it also shows how this technology serves as a source of energy in some countries around the world, which is a role associated with the energy potential available in each region. This point equally shows through numbers in GWh/year per km2 reservoir surface. Last but not least, it is the influence that this technology has had on the environment, its contributions for improving and evaluating from an environmental point of view.

  20. Spatiotemporal Information Organization and Visualization on Tidal Level (United States)

    Huang, B.; Zhang, Y.; Wang, Y.; Liu, Q.


    The amount and location of oceanographic stations vary in different time and the observation information of the same station shows temporality. Hence, ocean observation information has strong spatiotemporal characteristics. This article firstly introduces storage strategy and representation method of spatiotemporal information on tidal level. Then the prototype system was built with the ability of storing, updating, analyzing, and early warning of tidal level in Shandong Peninsula of China. The system achieves the inquiry and visualization of realtime and historical information of oceanographic stations, which provides technical support for oceanographers and decisionmakers.

  1. Extreme Value Analysis of Tidal Stream Velocity Perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Samuel; Thomson, Jim; Polagye, Brian; Richmond, Marshall C.; Durgesh, Vibhav; Bryden, Ian


    This paper presents a statistical extreme value analysis of maximum velocity perturbations from the mean flow speed in a tidal stream. This study was performed using tidal velocity data measured using both an Acoustic Doppler Velocimeter (ADV) and an Acoustic Doppler Current Profiler (ADCP) at the same location which allows for direct comparison of predictions. The extreme value analysis implements of a Peak-Over-Threshold method to explore the effect of perturbation length and time scale on the magnitude of a 50-year perturbation.

  2. Tidal breathing analysis as a measure of airway obstruction in children three years of age and older. (United States)

    van der Ent, C K; Brackel, H J; van der Laag, J; Bogaard, J M


    This study was designed to evaluate the value and applicability of tidal breathing pattern analysis to assess airflow obstruction in young children. The time needed to reach maximal tidal expiratory flow (TME) divided by total expiratory time (TE) was measured in 228 healthy children 3 to 11 yr of age, 64 patients with asthma, and 12 children with cystic fibrosis. In 70 patients both TME/TE and forced maximal expiratory flow volume (MEFV) parameters were measured. The mean TME/TE in healthy subjects was 43.0 +/- 7.6%. The within-subject reproducibility was high (repeatability index, 5.3%). In the asthmatic patients the mean TME/TE was significantly lower (30.0 +/- 8.2%, p or = 0.80 was lower when compared with age-matched normal subjects (30.9 +/- 8.5, p < 0.0001), but it was in a higher range when compared with asthmatics with FEV1/FVC < 0.80 (25.9 +/- 7.9, p < 0.001). In the cystic fibrosis group the mean TME/TE was 27.4 +/- 10.7% without a significant change after bronchodilation. TME/TE correlated significantly with MEFV parameters. Tidal breathing analysis proved easy to perform in children older than 3 yr of age. The TME/TE ratio may be a reliable and simple indicator for airway obstruction.

  3. Lung volumes in giraffes, Giraffa camelopardalis. (United States)

    Mitchell, G; Skinner, J D


    We have measured lung mass and trachea dimensions in 46 giraffes of both genders ranging in body mass from 147 kg to 1441 kg, calculated static and dynamic lung volumes, and developed allometric equations that relate changes in them to growth. We found that relative lung mass is 0.6±0.2% of body mass which is significantly less than it is in other mammals (1.1±0.1%). Total lung volume is significantly smaller (46.2±5.9 mL kg⁻¹) than in similar sized mammals (75.0±2.1 mL kg⁻¹). The lung volume:body mass ratio decreases during growth rather than increase as it does in other mammals. Tracheal diameter is significantly narrower than in similar sized mammals but dead space volume (2.9±0.5 mL kg⁻¹) is larger than in similar sized mammals (2.4±0.1 mL kg⁻¹). Our calculations suggest that tidal volume (10.5±0.2 mL kg⁻¹) is increased compared to that in other mammals(10.0±0.2 mL kg⁻¹) so that the dead space:tidal volume ratio is the same as in other mammals. Calculated Functional Residual Capacity is smaller than predicted (53.4±3.5 vs 33.7±0.6 mL kg⁻¹) as is Expiratory Reserve Volume (47.4±2.6 vs 27.2±1.0 mL kg⁻¹, but Residual Volume (6.0±0.4 mL kg⁻¹) is the same as in other similar sized mammals (6.0±0.9 mL kg⁻¹. Our calculations suggest that Inspiratory Reserve Volume is significantly reduced in size (11.6±1.6 vs 3.8±2.4 mL kg⁻¹), and, if so, the capacity to increase tidal volume is limited. Calculated dynamic lung volumes were the same as in similar sized mammals. We have concluded that giraffe morphology has resulted in lung volumes that are significantly different to that of similar sized mammals, but these changes do not compromise ventilatory capacity. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Tidal Analysis Using Time–Frequency Signal Processing and Information Clustering

    Directory of Open Access Journals (Sweden)

    Antonio M. Lopes


    Full Text Available Geophysical time series have a complex nature that poses challenges to reaching assertive conclusions, and require advanced mathematical and computational tools to unravel embedded information. In this paper, time–frequency methods and hierarchical clustering (HC techniques are combined for processing and visualizing tidal information. In a first phase, the raw data are pre-processed for estimating missing values and obtaining dimensionless reliable time series. In a second phase, the Jensen–Shannon divergence is adopted for measuring dissimilarities between data collected at several stations. The signals are compared in the frequency and time–frequency domains, and the HC is applied to visualize hidden relationships. In a third phase, the long-range behavior of tides is studied by means of power law functions. Numerical examples demonstrate the effectiveness of the approach when dealing with a large volume of real-world data.

  5. The Power Coefficient in the Theory of Energy Extraction from Tidal Channels (United States)

    Cummins, P. F.


    The maximum average power available from a fence of turbines deployed in a tidal channel is given by the simple formula, Ρ=γρgaQmax, where ρga is the amplitude of pressure difference across ends of the channel, Qmax is the maximum volume flux through the channel in the undisturbed state (i.e., before turbines are deployed), and γ is a numerical coefficient. The latter depends only weakly on the underlying dynamical balance of the channel. This is shown to be consequence of quadratic drag and changes to the natural impedance of the channel as deployment of turbines impedes the flow. Additionally, it is shown that the power coefficient γ is relatively insensitive to the form of the turbine drag.

  6. Tidal influence on the diel vertical migration pattern of zooplankton in a tropical monsoonal Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Vineetha, G.; Jyothibabu, R.; Madhu, N.V.; Kusum, K.K.; Sooria, P.M.; Shivaprasad, A.; Reny, P.D.; Deepak, M.P.

    habitats is often determined by their dominant behavioral patterns: diel vertical migration (DVM) and tidal vertical migration (TVM). The modes of these endogenous rhythms often vary among estuaries based on the river runoff and tidal characteristics...

  7. Adélie penguin foraging location predicted by tidal regime switching. (United States)

    Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh


    Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

  8. Assessment of Energy Production Potential from Tidal Streams in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Kevin A. [Georgia Inst. of Technology, Savannah, GA (United States); Fritz, Hermann M. [Georgia Inst. of Technology, Savannah, GA (United States); French, Steven P. [Georgia Inst. of Technology, Atlanta, GA (United States); Smith, Brennan T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Neary, Vincent [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    The project documented in this report created a national database of tidal stream energy potential, as well as a GIS tool usable by industry in order to accelerate the market for tidal energy conversion technology.

  9. Tidal extension and sea-level rise: recommendations for a research agenda (United States)

    Ensign, Scott H.; Noe, Gregory


    Sea-level rise is pushing freshwater tides upstream into formerly non-tidal rivers. This tidal extension may increase the area of tidal freshwater ecosystems and offset loss of ecosystem functions due to salinization downstream. Without considering how gains in ecosystem functions could offset losses, landscape-scale assessments of ecosystem functions may be biased toward worst-case scenarios of loss. To stimulate research on this concept, we address three fundamental questions about tidal extension: Where will tidal extension be most evident, and can we measure it? What ecosystem functions are influenced by tidal extension, and how can we measure them? How do watershed processes, climate change, and tidal extension interact to affect ecosystem functions? Our preliminary answers lead to recommendations that will advance tidal extension research, enable better predictions of the impacts of sea-level rise, and help balance the landscape-scale benefits of ecosystem function with costs of response.

  10. Determining Tidal Phase Differences from X-Band Radar Images (United States)

    Newman, Kieran; Bell, Paul; Brown, Jennifer; Plater, Andrew


    Introduction Previous work by Bell et. al. (2016) has developed a method using X-band marine radar to measure intertidal bathymetry, using the waterline as a level over a spring-neap tidal cycle. This has been used in the Dee Estuary to give a good representation of the bathymetry in the area. However, there are some sources of inaccuracy in the method, as a uniform spatial tidal signal is assumed over the entire domain. Motivation The method used by Bell et. al. (2016) applies a spatially uniform tidal signal to the entire domain. This fails to account for fine-scale variations in water level and tidal phase. While methods are being developed to account for small-scale water level variations using high resolution modelling, a method to determine tidal phase variations directly from the radar intensity images could be advantageous operationally. Methods The tidal phase has been computed using two different methods, with hourly averaged images from 2008. In the first method, the cross-correlation between each raw pixel time series and a tidal signal at a number of lags is calculated, and the lag with the highest correlation to the pixel series is recorded. For the second method, the same method of correlation is used on signals generated by tracking movement of buoys, which show up strongly in the radar image as they move on their moorings with the tidal currents. There is a broad agreement between the two methods, but validation is needed to determine the relative accuracy. The phase has also been calculated using a Fourier decomposition, and agrees broadly with the above methods. Work also needs to be done to separate areas where the recorded phase is due to tidal current (mostly subtidal areas) or due to elevation (mostly the wetting/drying signal in intertidal areas), by classifying radar intensities by the phases and amplitudes of the tides. Filtering out signal variations due to wind strength and attenuation of the radar signal will also be applied. Validation

  11. ABoVE: Study Domain and Standard Reference Grids (United States)

    National Aeronautics and Space Administration — The Arctic - Boreal Vulnerability Experiment (ABoVE) has developed two standardized spatial data products to expedite coordination of research activities and to...

  12. Aileler, Öğretmenler ve Dil ve Konuşma Terapistlerinin Çocuklardaki Dil ve Konuşma Bozukluklarına Yönelik Tutum ve Bilgilerinin Değerlendirilmesi

    Directory of Open Access Journals (Sweden)

    Bülent Toğram


    Full Text Available Çocuklardaki iletişim sorunları aile bildirimleri, öğretmen raporları ve dil ve konuşma terapistleri (DKT tarafından yapılan değerlendirmeler ile saptanmaktadır. Dil ve konuşma bozukluklarının önlenmesi ve terapisinde işbirliği içinde bulunmaları gereken bu üçlü grubun konuya ilişkin görüş ve tutumları alanyazında önemli bulunmaktadır. Bu çalışmanın amacı, ebeveynlerin, öğretmenlerin ve DKT’lerin dil ve konuşma bozuklukları alanındaki sorumluluk ve rollerini nasıl algıladıklarını, dil ve konuşma bozukluğu olan çocuğun akademik ve sosyal başarısına yönelik tutumlarını, dil ve konuşma bozukluklarının nedenleri ve terapisine yönelik düşüncelerini betimlemektir. Çalışmaya 37 aile bireyi, 46 öğretmen ve 35 DKT katılmıştır. Anket yoluyla elde edilen veriler her grubun konuya ilişkin bilgisini ortaya koymak için karşılaştırılmıştır. Dil ve konuşma bozukluğu olan çocukların akademik/sosyal başarılarına yönelik tutumlarında diğer katılımcı gruplara göre öğretmenlerin, çocukların terapi gereksinimlerine yönelik tutumlarında ise ailelerin daha kararsız tutumlar geliştirdikleri dikkat çekmektedir. Dil ve konuşma bozukluklarının nedenleri ve terapi eksikliklerine yönelik bilgilerinde grupların öncelikli sıralamalarının farklılaştığı görülmüştür. Speech and language disorders (SLD in children have been determined by parental reports, teacher reports and assessments by speech-language therapists. Therefore, the family members, teachers and speech and language therapists should be in continuous collaboration during the intervention and therapy process of the individuals with SLD. The collaborators’ attitudes toward the impact of SLD on the child have been highlighted in the literature. The purpose of the study is to determine parents’ and teachers’ and speech and language therapists’ awareness toward their roles and

  13. Galdos’un Dona Perfecta ve Misericordia eserlerinde realizm


    YÜCEL, Aslıhan


      XIX. yüzyılda İspanya, ülkeyi ekonomik bir krize sürükleyen Güney Amerika sömürgelerinin kaybedilmesi ve Bağımsızlık Savaşı yüzünden zor zamanlar geçiriyordu. Ayrıca, Carlistler ve liberaller arasındaki savaş, politik ve sosyal olarak ülkeyi yıpratmıştı.

    Böyle bir zamanda, insanları rüyalarından uyandırmak ve ne kadar üzücü olursa olsun onlara gerçeği göstermek için Realizm akımı ortaya çıktı. Benito Pé...

  14. A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Taiping; Yang, Zhaoqing


    Previous tidal energy projects in Puget Sound have focused on major deep channels such as Admiralty Inlet that have a larger power potential but pose greater technical challenges than minor tidal channels connecting to small sub-basins. This paper focuses on the possibility of extracting energy from minor tidal channels by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and calibrated for tidal elevations and currents. We examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. The model suggests that with the proposed level of energy extraction, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.

  15. Veri Madenciliği ve Bilgi Merkezleri

    Directory of Open Access Journals (Sweden)

    Sacit Arslantekin


    Full Text Available Günümüzde bir çok kurum ve kuruluş işlem ve hizmetlerini otomasyona geçirmiş­tir. Bu kurum ve kuruluşlar kullanıcı odaklı olarak faaliyetlerini Internet üzerin­den de sürdürmeye çalışırken, daha büyük kazanımlar elde etme amacındadır. Elde etmek istedikleri kazanımlar kalitelerini arttırmalarının yanında, kullanıcı memnuniyetine de dayanmaktadır. Kullanıcılarının ürün ve hizmetlerinden ne ka­dar yararlandıkları, memnun kalıp kalmadıkları ancak, onların davranışları iz­lenerek ortaya konabilir. Bilgi merkezleri de kullanıcı davranışlarını izleyen ve elde ettiği bilgilere göre işlem ve hizmetlerini geliştiren kurumlardandır. Bilgisa­yara dayalı işler sürecinde otomatik olarak oluşan verinin işlenip analiz edilme­si, bilgi merkezlerine çalışanları ve kullanıcıları hakkında anlamlı bilgiler suna­caktır. İşlemler ve kullanım sırasında oluşan veri büyük bir yığın halinde olup, bu yığından anlamlı veri elde edilmesi bazı özel yöntem ve tekniklerin kullanıl­masını gerektirmektedir. Veri madenciliği oluşan verilerin toplanması, bir yapay zeka aracılığıyla analiz edilmesi ve yorumlanarak amaç ve hedeflere ulaşmada gerekli adımları önermesi sürecidir.

  16. Veri Madenciliği ve Bilgi Merkezleri

    Directory of Open Access Journals (Sweden)

    Sacit Arslantekin


    Full Text Available Günümüzde bir çok kurum ve kuruluş işlem ve hizmetlerini otomasyona geçirmiştir. Bu kurum ve kuruluşlar kullanıcı odaklı olarak faaliyetlerini Internet üzerinden de sürdürmeye çalışırken, daha büyük kazanımlar elde etme amacındadır. Elde etmek istedikleri kazanımlar kalitelerini arttırmalarının yanında, kullanıcı memnuniyetine de dayanmaktadır. Kullanıcılarının ürün ve hizmetlerinden ne kadar yararlandıkları, memnun kalıp kalmadıkları ancak, onların davranışları izlenerek ortaya konabilir. Bilgi merkezleri de kullanıcı davranışlarını izleyen ve elde ettiği bilgilere göre işlem ve hizmetlerini geliştiren kurumlardandır. Bilgisayara dayalı işler sürecinde otomatik olarak oluşan verinin işlenip analiz edilmesi, bilgi merkezlerine çalışanları ve kullanıcıları hakkında anlamlı bilgiler sunacaktır. İşlemler ve kullanım sırasında oluşan veri büyük bir yığın halinde olup, bu yığından anlamlı veri elde edilmesi bazı özel yöntem ve tekniklerin kullanılmasını gerektirmektedir. Veri madenciliği oluşan verilerin toplanması, bir yapay zeka aracılığıyla analiz edilmesi ve yorumlanarak amaç ve hedeflere ulaşmada gerekli adımları önermesi sürecidir.

  17. Probiyotikler ve Kullanım Alanları

    Directory of Open Access Journals (Sweden)

    Başar Uymaz


    Full Text Available Gıdaların üretiminde tüketici sağlığını destekleyici ve immün sistemi uyaran etkilere sahip mikroorganizmaların kullanımı giderek artmaktadır. Bu mikroorganizmaların önemli bir grubunu teşkil eden probiyotiklerin gastrointestinal sistem hastalıklarının engellenmesi ve tedavisinde ve normal mikrofloranın oluşumunda önemli bir rol oynadığı klinik denemelerle belirlenmiştir. Diğer yandan probiyotiklerin, suştan suşa farklılık gösteren gıda koruyucu etkileri ve değişik hastalıkların tedavisinde kullanım potansiyelleri üzerinde çalışmalar devam etmektedir. Özellikle çocuklarda görülen akut diyare ve antibiyotik kullanımına bağlı diyarenin tedavisinde etkin kullanım potansiyeli taşıyan probiyotik preparatları geliştirilmiştir. Bu derleme makalesinde probiyotik suşların seçiminde kullanılan karakteristikler, kullanım olanakları ve tedavi edici potansiyelleri, güncel bilgiler taranarak verilmiştir.

  18. Diurnal and semi-diurnal tidal currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S; Gouveia, A; Shetye, S

    Current meter records from two depths, approximately 1000 m, at three mooring in the deep mid-Arabian Sea were used to study tidal components. Tidal ellipses for the semi-diurnal (M2, S2 and K2) and the diurnal (K1 and P1) tidal constituents have...

  19. 75 FR 59256 - Eastport Tidal Power LLC; Notice of Competing Preliminary Permit Application Accepted for Filing... (United States)


    ... Energy Regulatory Commission Eastport Tidal Power LLC; Notice of Competing Preliminary Permit Application..., Eastport Tidal Power LLC filed an application for a preliminary permit, pursuant to section 4(f) of the Federal Power Act (FPA), proposing to study the feasibility of the Half Moon Cove Tidal Power Plant...

  20. 75 FR 78236 - Pennamaquan Tidal Power, LLC; Notice of Preliminary Permit Application Accepted for Filing and... (United States)


    ... Energy Regulatory Commission Pennamaquan Tidal Power, LLC; Notice of Preliminary Permit Application..., 2010. On November 22, 2010, Pennamaquan Tidal Power, LLC filed an application for a preliminary permit... Pennamaquan Tidal Power Plant Project to be located on the Pennamaquan River and Cobscook Bay, Washington...

  1. Modeling the growth and migration of sandy shoals on ebb-tidal deltas

    NARCIS (Netherlands)

    Ridderinkhof, W.; de Swart, H. E.; van der Vegt, M.; Hoekstra, P.


    Coherent sandy shoals that migrate toward the downdrift coast are observed on many ebb-tidal deltas. In this study, processes that cause the growth and migration of shoals on ebb-tidal deltas are identified. Moreover, the effect of the incident wave energy and the tidal prism of an inlet on the

  2. Turbidity maximum formation in a well-mixed macrotidal estuary : The role of tidal pumping

    NARCIS (Netherlands)

    Yu, Q.; Wang, Y.; Gao, J.; Gao, S.; Flemming, B.


    Traditionally, vertical circulation (induced by gravity circulation and tidal straining), tidal pumping, and resuspension are suggested as the major processes for the formation and maintenance of the estuarine turbidity maximum (ETM). Due to strong mixing, tidal pumping is considered as the

  3. Residual water transport in the Marsdiep tidal inlet inferred from observations and a numerical model

    NARCIS (Netherlands)

    Sassi, M.G.; Gerkema, T.; Duran-Matute, M.; Nauw, J.J.


    At tidal inlets, large amounts of water are exchanged with the adjacent sea during the tidal cycle.The residual flows, the net effect of ebb and flood, are generally small compared with the gross flux;they vary in magnitude and sign from one tidal period to the other; and their long-term mean

  4. Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.


    , there are no reports that these signals have been used to infer subsurface structure. We use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. Themodel derived from more than 12 years of satellite data reveals...

  5. Detecting areal changes in tidal flats after sea dike construction ...

    Indian Academy of Sciences (India)

    The main objective of this study was to estimate changes in the area of tidal flats that occurred after sea dike construction on the western coast of South Korea using Landsat-TM images. Applying the ISODATA ... Department of Biosystems Engineering, Auburn University, 200 Tom E. Corley Building, Auburn, AL36849, USA.

  6. About Tidal Evolution of Quasi-Periodic Orbits of Satellites (United States)

    Ershkov, Sergey V.


    Tidal interactions between Planet and its satellites are known to be the main phenomena, which are determining the orbital evolution of the satellites. The modern ansatz in the theory of tidal dissipation in Saturn was developed previously by the international team of scientists from various countries in the field of celestial mechanics. Our applying to the theory of tidal dissipation concerns the investigating of the system of ODE-equations (ordinary differential equations) that govern the orbital evolution of the satellites; such an extremely non-linear system of 2 ordinary differential equations describes the mutual internal dynamics for the eccentricity of the orbit along with involving the semi-major axis of the proper satellite into such a monstrous equations. In our derivation, we have presented the elegant analytical solutions to the system above; so, the motivation of our ansatz is to transform the previously presented system of equations to the convenient form, in which the minimum of numerical calculations are required to obtain the final solutions. Preferably, it should be the analytical solutions; we have presented the solution as a set of quasi- periodic cycles via re-inversing of the proper ultra- elliptical integral. It means a quasi-periodic character of the evolution of the eccentricity, of the semi-major axis for the satellite orbit as well as of the quasi-periodic character of the tidal dissipation in the Planet.

  7. Bedload and nearbed detritus transport in a tidal saltmarsh creek

    NARCIS (Netherlands)

    Hemminga, M.A.; Cattrijsse, A.; Wielemaker, A.


    Bedload and nearbed transport of coarse (>1 mm) detritus particles were investigated in a tidal creek of a salt marsh in the Westerschelde estuary (south-west Netherlands). Using a fyke net positioned on the creek bottom, hourly transport through the creek was measured during 14 flood-ebb cycles in

  8. Representing kelp forests in a tidal circulation model (United States)

    Wu, Yongsheng; Hannah, Charles G.; O'Flaherty-Sproul, Mitchell; Thupaki, Pramod


    The presence of kelp beds in the water column generates drag to flows and modifies hydrodynamic processes. In this paper we examine the modifications of tidal flows in the Hecate Strait by including an explicit representation of the kelp-induced drag in a three-dimensional numerical model. The model is evaluated against a theoretical solution and it agrees well with the theory. Model results show that kelp beds significantly change tidal circulation structures by damping tidal velocity by 40-80% in interiors of the beds, but enhancing tidal velocity by 15% along the edges. Comparing terms in momentum equations shows that the momentum flux caused by the kelp drag is able to become a dominant term with a magnitude comparable to that of the horizontal pressure gradient. Simulating the effects of kelp beds on particle trajectories shows that the drag due to kelp-beds decreases the dispersion rate of particles in the interiors of kelp forests, but increases the dispersion rate along the edges. Kelp beds form barriers along the edges and prevent particles from outside entering the interiors of kelp beds. The dispersion rate is in an inverse relationship to the kelp density in kelp-bed interiors, while in a positive relationship to the kelp density along edges.

  9. Hydrodynamic modelling of tidal inlets in Hue, Vietnam

    NARCIS (Netherlands)

    Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.


    Application of an one-dimensional numerical model for hydrodynamic simulation of a complex lagooninlet system in Vietnam is presented. Model results help to get a better understanding on the behaviour of the system. Based on the numerical model results and analytic solutions, stability of tidal

  10. Effects of seasonal variation and tidal regimes on macrobenthic ...

    African Journals Online (AJOL)

    An assessment of the effects of seasonal variation and tidal regimes on the distribution and density of macrobenthic invertebrates of the coastal Warri River, southern Nigeria was carried out from July 2014 to February 2015. Samples were collected from five longitudinal stations from headwater to mouth during high and low ...

  11. General relativistic tidal work for Papapetrou, Weinberg and Goldberg pseudotensors

    CERN Document Server

    So, Lau Loi


    In 1998 Thorne claimed that all pseudotensors give the same tidal work as the Newtonian theory. In 1999, Purdue used the Landau-Lifshitz pseudotensor to calculate the tidal heating and the result matched with the Newtonian gravity. Soon after in 2001, Favata employed the same method to examine the Einstein, Bergmann-Thomson and M{\\o}ller pseudotensors, all of them give the same result as Purdue did. Inspired by the work of Purdue and Favata, for the completeness, here we manipulate the tidal work for Papapetrou, Weinberg and Goldberg pseudotensors. We obtained the same tidal work as Purdue achieved. In addition, we emphasize that a suitable gravitational energy-momentum pseudotensor requires fulfill the inside matter condition and all of the classical pseudotensors pass this test except M$\\o$ller. Moreover, we constructed a general pseudotesnor which is modified by 13 linear artificial higher order terms combination with Einstein pseudotensor. We find that the result agrees with Thorne's prediction, i.e., rel...

  12. Large-scale structure and gravitational waves. III. Tidal effects (United States)

    Schmidt, Fabian; Pajer, Enrico; Zaldarriaga, Matias


    The leading locally observable effect of a long-wavelength metric perturbation corresponds to a tidal field. We derive the tidal field induced by scalar, vector, and tensor perturbations, and use second-order perturbation theory to calculate the effect on the locally measured small-scale density fluctuations. For subhorizon scalar perturbations, we recover the standard perturbation theory result (F2 kernel). For tensor modes of wavenumber kL, we find that effects persist for kLτ ≫1, i.e. even long after the gravitational wave has entered the horizon and redshifted away ("fossil effect"). We then use these results, combined with the "ruler perturbations" of F. Schmidt and D. Jeong [Phys. Rev. D 86, 083527 (2012)], to predict the observed distortion of the small-scale matter correlation function induced by a long-wavelength tensor mode. We also estimate the observed signal in the B mode of the cosmic shear from a gravitational wave background, including both tidal (intrinsic alignment) and projection (lensing) effects. The nonvanishing tidal effect in the kLτ≫1 limit significantly increases the intrinsic alignment contribution to shear B modes, especially at low redshifts z≲2.

  13. A new analytical framework for tidal propagation in estuaries

    NARCIS (Netherlands)

    Cai, H.


    The ultimate aim of this thesis is to enhance our understanding of tidal wave propagation in convergent alluvial estuaries (of infinite length). In the process, a new analytical model has been developed as a function of externally defined dimensionless parameters describing friction, channel

  14. End-tidal carbon dioxide monitoring during flexible fiberoptic ...

    African Journals Online (AJOL)

    Arterial oxygen saturation is usually monitored with pulse oximetry Spo2) during FFB; END-TIDAL Pco2) (ET-Pco2) monitoring is not routinely used. Two-hundred patients were studied between May 1998 till April 2003, at the divisions of chest surgery and pulmonolgy at King Hussein Medical Center, (khmc). Their ages ...

  15. Morphodynamics of the Manyema tidal delta at Kunduchi, Tanzania ...

    African Journals Online (AJOL)

    The prevailing northward longshore drift of beach sand on the northern part of Msasani Bay, north of Dar es Salaam, is interrupted at Kunduchi by the tidal flushing of Manyema Creek, a mangrove ecosystem partially developed for salt production. Shoreline changes around the creek mouth in recent decades have eroded ...

  16. Tidal phenomena in reservoirs; Fenomeno de mare em reservatorios

    Energy Technology Data Exchange (ETDEWEB)

    Pinilla Cortes, John Freddy


    This work models the oceanic tidal effect on reservoirs by coupling geomechanic principles with equations for fluid in a deformable porous media. The coupling revealed the importance of establishing properly the system compressibility under the various possible configurations of the loading system. The basic models for infinite reservoir, constant outer-pressure reservoir and closed reservoir were considered. It was verified that it was possible to apply the superposition of effects on the solution for the basic models by carrying a simple transformation on the solution variable. The problem was treated by in the context of test analysis, concerning dimensionless form of variables and the inclusion of well effects. The solution for the infinite reservoir including tidal effects. The solution for the infinite reservoir including tidal effects was obtained in the Laplace space and was inverted numerically by using Crump's routine. The results were incorporated to conventional type curves, and were validated by comparison with real and simulated pressure test data. Finally, alternate practices were suggested to integrate the well test analysis in reservoirs affected by the tidal effect. (author)

  17. Modeling the dynamics of offshore tidal sand ridges

    NARCIS (Netherlands)

    Yuan, B.


    Tidal sand ridges are large-scale bedforms with horizontal dimensions of several kilometers and heights of tens of meters. They occur in the offshore area of shelf seas that have a wide range of water depths (10-200 m). Based on their present-day behavior, ridges are classified as `active' (sand

  18. Seed dynamics linked to variability in movement of tidal water

    NARCIS (Netherlands)

    Chang, E. R.; Veeneklaas, R. M.; Bakker, J. P.

    Question: Community structure may be influenced by patterns of dispersed seeds (seed rain) because they contribute to the template of plant community development. We explored factors influencing seed rain in a system dominated by tidal water, where direction and magnitude of water flow are difficult

  19. Bedform evolution in a tidal inlet referred from wavelet analysis

    DEFF Research Database (Denmark)

    Fraccascia, Serena; Winter, Christian; Ernstsen, Verner Brandbyge


    Bedforms are common morphological features in subaqueous and aeolian environments and their characterization is commonly the first step to better understand forcing factors acting in the system. The aim of this study was to investigate the spectral characteristics of compound bedforms in a tidal...


    Energy Technology Data Exchange (ETDEWEB)

    Li, Gongjie [Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States); Winn, Joshua N., E-mail: [Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)


    The obliquities of planet-hosting stars are clues about the formation of planetary systems. Previous observations led to the hypothesis that for close-in giant planets, spin–orbit alignment is enforced by tidal interactions. Here, we examine two problems with this hypothesis. First, Mazeh and coworkers recently used a new technique—based on the amplitude of starspot-induced photometric variability—to conclude that spin–orbit alignment is common even for relatively long-period planets, which would not be expected if tides were responsible. We re-examine the data and find a statistically significant correlation between photometric variability and planetary orbital period that is qualitatively consistent with tidal interactions. However it is still difficult to explain quantitatively, as it would require tides to be effective for periods as long as tens of days. Second, Rogers and Lin argued against a particular theory for tidal re-alignment by showing that initially retrograde systems would fail to be re-aligned, in contradiction with the observed prevalence of prograde systems. We investigate a simple model that overcomes this problem by taking into account the dissipation of inertial waves and the equilibrium tide, as well as magnetic braking. We identify a region of parameter space where re-alignment can be achieved, but it only works for close-in giant planets, and requires some fine tuning. Thus, while we find both problems to be more nuanced than they first appeared, the tidal model still has serious shortcomings.

  1. Energy storage inherent in large tidal turbine farms. (United States)

    Vennell, Ross; Adcock, Thomas A A


    While wind farms have no inherent storage to supply power in calm conditions, this paper demonstrates that large tidal turbine farms in channels have short-term energy storage. This storage lies in the inertia of the oscillating flow and can be used to exceed the previously published upper limit for power production by currents in a tidal channel, while simultaneously maintaining stronger currents. Inertial storage exploits the ability of large farms to manipulate the phase of the oscillating currents by varying the farm's drag coefficient. This work shows that by optimizing how a large farm's drag coefficient varies during the tidal cycle it is possible to have some flexibility about when power is produced. This flexibility can be used in many ways, e.g. producing more power, or to better meet short predictable peaks in demand. This flexibility also allows trading total power production off against meeting peak demand, or mitigating the flow speed reduction owing to power extraction. The effectiveness of inertial storage is governed by the frictional time scale relative to either the duration of a half tidal cycle or the duration of a peak in power demand, thus has greater benefits in larger channels.

  2. Simulating tidal turbines with mesh optimisation and RANS turbulence models

    NARCIS (Netherlands)

    Abolghasemi, A.; Piggott, M.D.; Spinneken, J.; Vire, A.; Cotter, C.J.


    A versatile numerical model for the simulation of flow past horizontal axis tidal turbines has been developed. Currently most large-scale marine models employed to study marine energy use the shallow water equations and therefore can fail to account for important turbulent physics. The model

  3. Long-Period Tidal Variations of the Earth's Rotation Rate (United States)

    Desai, S.; Gross, R.; Wahr, J.


    Long-period tidal variations of the Earth's rotation rate are caused by the redistribution of mass associated with the respective elastic solid Earth tides, the ocean tide heights, and the anelasticity of the Earth's mantle, and by the relative angular momentum associated with the long-period ocean tide currents.

  4. Intertidal deposits: river mouths, tidal flats, and coastal lagoons

    NARCIS (Netherlands)

    Eisma, D.; Boer, de P.L.; Cadee, G.C.; Dijkema, K.; Ridderinkhof, H.; Phillippart, C.


    Intertidal Deposits: River Mouths, Tidal Flats, and Coastal Lagoons combines the authors personal and professional experience with the mass of available literature to present a cohesive overview of intertidal deposits and the widely diverse conditions of their formation worldwide. This includes the

  5. Tidal propagation off the central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    and phases from a global tidal model in the open ocean and those at the coast are used to construct co-amplitude and co-phase lines of M2 and K1, which are the largest among the semi-diurnal and diurnal constituents respectively. One of the characteristic...

  6. Tidal strain observations in Chu-Chie, Taiwan (United States)

    Takemoto, Shuzo; Lee, Min; Chen, Chih-Yen; Kao, Ming-Chien; Mukai, Atsushi; Ikawa, Takeshi; Kuroda, Tohru; Abe, Taisuke


    In Chu-Chie, Taiwan, tidal strain observation with a borehole strainmeter system has been carried out since 2001. The Chu-Chie station (N23°31'39″, E120°35'59″, h = 300 m) is located in the central part of Taiwan and is about 40 km distant from the epicenter of the destructive Chi-Chi earthquake ( ML = 7.3) which occurred on September 21, 1999. The strainmeter system detects three components of horizontal strains in 82°, 202° and 322° measured from the North in clockwise directions using differential transformers. We analyzed tidal strains and determined amplitudes and phase lags of 13 major constituents by applying the tidal-analysis program BAYTAP-G to 1-year strain data of 2003. The "observed" tidal strain amplitudes were compared with the "theoretically expected" amplitudes that were obtained from the GOTIC2 program. As a result, the ratio of the observed amplitudes and the theoretically expected amplitudes ranges between 0.7 and 3.3. Some parts of these discrepancies may be caused by uncertainty of determination of scale factors of instruments. Other reasons to be considered are complicated geological and topographic effects around the observation site.

  7. Sediment discharge division at two tidally influenced river bifurcations

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Vermeulen, B.; Hidayat, H.


    [1] We characterize and quantify the sediment discharge division at two tidally influenced river bifurcations in response to mean flow and secondary circulation by employing a boat-mounted acoustic Doppler current profiler (ADCP), to survey transects at bifurcating branches during a semidiurnal

  8. Sociocultural Adaptation of Caboclos Communities to Extreme Tidal ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Project outputs will include early warning systems for extreme tidal events, information systems for decision-making, adaptation plans for district municipalities, policy briefs, ... Prise en compte des sexospécificités dans la gestion des déchets solides dans les zones urbaines et périurbaines (Amérique latine et Caraïbes).

  9. End-tidal carbon dioxide monitoring during flexible fiberoptic ...

    African Journals Online (AJOL)

    No correlation was found between decreasing ET-Pco2 and Spo2 decreased during bronchoscopy. We also speculate that this reflects airway obstruction by the instrument. Further studies and more experimental analysis in this field are recommended. Keywords: end-tidal Pco2, fiber optic bronchoscopy, Spo2

  10. Uptake of dissolved inorganic nitrogen in turbid, tidal estuaries

    NARCIS (Netherlands)

    Middelburg, J.J.; Nieuwenhuize, J.


    Ammonium and nitrate uptake was measured in 6 European tidal estuaries (Ems, Rhine, Scheldt, Loire, Gironde and Douro) using N-15-tracer techniques. Uptake rates of ammonium and nitrate ranged from 0.005 to 1.56 mu mol N l(-1) h(-1) and 0.00025 to 0.25 mu mol N l(-1) h(-1), respectively, and

  11. Mass Transfer and Tidal Dynamics in White Dwarf Binary Systems (United States)

    Gerber, Jeffrey; Fuller, J.


    Compact white dwarf (WD) binary systems (with orbital periods ranging from minutes to hours) can produce a variety of interesting astrophysical objects (e.g., type Ia supernovae, AM CVn systems, R Cor Bor stars, sdB stars) upon the onset of mass transfer. These systems are driven toward Roche lobe overflow by the emission of gravitational radiation, but it is not known whether the mass transfer will be stable (forming an Am CVn system) or become unstable (resulting in a merger). We analyze how the combined effects of mass transfer and tidal torques affect the evolution of these systems by creating numerical models with the MESA stellar evolution program. Using new calculations of the tidal torque in rotating WDs, we predict the outcome of mass transfer in these systems as a function of the masses of the WD components. We find that the stability of mass transfer depends primarily on the peak mass transfer rate near the period minimum, which is highly dependent on the WD masses and on the strength of the tidal torques. Except for low WD accretor masses, the tidal torques are insufficient to significantly increase the stability of mass transfer. We find that mass transfer is generally unstable for WD donor masses greater than about 0.25 solar masses, and that the 12 minute system SDSS J0615 will end its inspiral in a WD merger, likely producing an R Cor Bor star.

  12. Tidal exchange of ichthyoplankton in the Swartkops estuary mouth ...

    African Journals Online (AJOL)

    Tidal exchange of fish eggs, larvae and juveniles in the mouth of the Swartkops estuary was examined by plankton and seine-netting during two 24-h sampling sessions. Small larvae of resident estuarlne species such as Caffrogobius multifasciatus, Psammogobius knysnaensis and Omobranchus woodi appear to be ...

  13. Enterococcus faecium ve Enterococcus faecalis 'in Starter ve Probiyotik Kültür Özellikleri


    Erginkaya, Zerrin; Yurdakul, Naci Erhan; Karakaş, Ayşegül


    ÖzetEnterococcus faecium ve Enterococcus faecalis bazı gıdalarda organoleptik özellikleri iyileştirmenin yanı sıra lipolitik ve esterolitik aktivite, sitrattan yararlanma ile uçucu aromatik bileşikleri sentezleme gibi özellikleri nedeniyle bazı fermente süt ve et ürünlerinin olgunlaştırılması sırasında diğer laktik asit bakterileri ile birlikte starter kültür olarak kullanılmaktadır. Günümüzde Enterococcus 'ların gıda üretiminde starter kültür ve/veya probiyotik olarak kullanılmaları s...

  14. Enterococcus faecium ve Enterococcus faecalis 'in Starter ve Probiyotik Kültür Özellikleri


    Erginkaya, Zerrin; Yurdakul, Naci Erhan; Karakaş, Ayşegül


    ÖzetEnterococcus faecium ve Enterococcus faecalis bazı gıdalarda organoleptik özellikleri iyileştirmenin yanı sıra lipolitik ve esterolitik aktivite, sitrattan yararlanma ile uçucu aromatik bileşikleri sentezleme gibi özellikleri nedeniyle bazı fermente süt ve et ürünlerinin olgunlaştırılması sırasında diğer laktik asit bakterileri ile birlikte starter kültür olarak kullanılmaktadır. Günümüzde Enterococcus 'ların gıda üretiminde starter kültür ve/veya probiyotik olarak kullanılmala...

  15. Understanding tidal notch development: examples from tropical and Mediterranean coasts. (United States)

    Moses, Cherith; Furlani, Stefano; Kazmer, Miklos


    It has been suggested that tropical rock coasts exhibit morphological features that are different compared to other climatic regimes. But tidal notches, recesses extending along marine cliffs, are common to both tropical and Mediterranean coasts, and develop because of higher erosion rates in the intertidal zone compared to the supratidal or subtidal zone. They are widely used as geomorphological indicators of sea level change and tectonic movement. For this purpose their formation is usually associated with wave erosion, although the role of bioerosion and weathering, e.g. solution, are sometimes given more importance. In some cases wave erosion may simply remove weathered materials rather than directly eroding the rock e.g. on granite and sandstone coasts. Rock type is also thought to be important in the development of tidal notches, with those developed on limestone coasts said to provide more reliable indicators than other rock types. As well as indicating the vertical position of former sea levels, tidal notches have also been used to estimate the duration of stillstands (e.g. on harder limestones) and to calculate the periodicity of cliff-falls (e.g. on softer limestones). Despite their importance, the genesis, rate of development and global variations in morphology of tidal notches are still not fully understood. We assess present understanding of the roles of climate, tidal range, wave conditions and rock type by reviewing studies of morphology, rates and modes of tidal notch development on Mediterranean and tropical coasts. There is a dearth of quantitative data and so we present notch erosion rates directly measured using the Micro Erosion Meter (MEM) and Traversing MEM (TMEM) on limestone on the Northern Adriatic and Andaman Sea coasts: the former collected over > 10 years on the Trieste and Istrian coasts and > 3 years on an experimental vertical slab in the Gulf of Trieste; the latter over a 10 year period at Krabi in Southern Thailand. We relate these

  16. Testing the tidal alignment model of galaxy intrinsic alignment

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Seljak, Uroš [Department of Physics and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); McQuinn, Matthew, E-mail:, E-mail:, E-mail: [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)


    Weak gravitational lensing has become a powerful probe of large-scale structure and cosmological parameters. Precision weak lensing measurements require an understanding of the intrinsic alignment of galaxy ellipticities, which can in turn inform models of galaxy formation. It is hypothesized that elliptical galaxies align with the background tidal field and that this alignment mechanism dominates the correlation between ellipticities on cosmological scales (in the absence of lensing). We use recent large-scale structure measurements from the Sloan Digital Sky Survey to test this picture with several statistics: (1) the correlation between ellipticity and galaxy overdensity, w{sub g+}; (2) the intrinsic alignment auto-correlation functions; (3) the correlation functions of curl-free, E, and divergence-free, B, modes, the latter of which is zero in the linear tidal alignment theory; (4) the alignment correlation function, w{sub g}(r{sub p},θ), a recently developed statistic that generalizes the galaxy correlation function to account for the angle between the galaxy separation vector and the principle axis of ellipticity. We show that recent measurements are largely consistent with the tidal alignment model and discuss dependence on galaxy luminosity. In addition, we show that at linear order the tidal alignment model predicts that the angular dependence of w{sub g}(r{sub p},θ) is simply w{sub g+}(r{sub p})cos (2θ) and that this dependence is consistent with recent measurements. We also study how stochastic nonlinear contributions to galaxy ellipticity impact these statistics. We find that a significant fraction of the observed LRG ellipticity can be explained by alignment with the tidal field on scales ∼> 10 \\hMpc. These considerations are relevant to galaxy formation and evolution.

  17. Net transport of suspended matter due to tidal straining (United States)

    Jones, S. E.; Jago, C. F.; Simpson, J. H.; Rippeth, T. P.


    Net transport of suspended particulate matter (SPM) is well-known in tidal regions where there is time-velocity asymmetry due to frictional modification of the tide in shallow water. We present here observations which show a new mechanism for net flux of SPM in response to tidal straining in a region of freshwater influence (ROFI). In situ measurements of the particle size of suspended particulate matter (SPM) and turbulent energy dissipation have been made at a site in Liverpool Bay (Irish Sea) where there is significant resuspension of particles from the muddy sand substrate during spring tides. This is a ROFI where tidal straining dominates the temporal development of turbulence. On a spring tide the water column tries to stratify on the ebb and destratify on the flood, but these tendencies are masked by mixing due to tidal stirring. Nevertheless, there is a marked excess of TKE dissipation rate E on the flood, especially in the upper part of the water column. Resuspension occurs on both flood and ebb, but SPM flux is strongly asymmetric with a net shorewards component. Asymmetry is most pronounced for the larger particles which comprise most of the mass. Enhanced ? on the flood mixes large particles upwards into faster flowing water, which increases the flux. Comparable upwards mixing of large particles does not occur on the ebb where enhanced E is confined to slower bottom waters. The net flux is not seen on neap tides because, although there is more stratification due to tidal straining, there is essentially no resuspension. The net flux on springs is undoubtedly an important component of SPM transport (and any comparable particulates) in coastal regions.

  18. Modeling the nonlinear effect of wind on rectilinear tidal flow (United States)

    Ruessink, B. G.; Houwman, K. T.; Grasmeijer, B. T.


    Observations of near-bed alongshore flow in 4-10 m depth at Terschelling, Netherlands, show that strong alongshore winds (≈15-20 m/s) in the flood direction reduce the tide current range and alter the tidal flow curve by bringing maximum flood flow forward in time and delaying maximum ebb flow. These nonlinear effects, which are more pronounced in shallower water, are reproduced well by a single-point model in the vertical driven by large-scale (O(km)) sea surface gradients and wind stress, using a quadratic bottom stress formulation and a time-dependent eddy viscosity derived from a k-ɛ turbulence closure model. Subsequent idealized model simulations using a (Terschelling based) M2 sea-surface gradient and wind speeds between 0 and 20 m/s show that the wind-induced modifications of the tidal flow are consistent with the interaction of the wind-induced flow with the tidal flow through the quadratic bed stress. The wind-driven flow enhances friction during the flood phase more than it reduces friction during the ebb flow, thereby increasing friction over a tidal cycle and, as a consequence, reducing the tide current range. The predicted increase in asymmetry of bed friction during flood and ebb flow with increasing wind speed also increases (decreases) the M4 (M6) amplitude, consistent with the observations. The M4/M2 amplitude ratio is predicted to be largest when the flow has just become unidirectional (that is, when the wind-driven flow equals the tidal current).

  19. Cost Assessment Methodology and Economic Viability of Tidal Energy Projects

    Directory of Open Access Journals (Sweden)

    Eva Segura


    Full Text Available The exploitation of technologies with which to harness the energy from ocean currents will have considerable possibilities in the future thanks to their enormous potential for electricity production and their high predictability. In this respect, the development of methodologies for the economic viability of these technologies is fundamental to the attainment of a consistent quantification of their costs and the discovery of their economic viability, while simultaneously attracting investment in these technologies. This paper presents a methodology with which to determine the economic viability of tidal energy projects, which includes a technical study of the life-cycle costs into which the development of a tidal farm can be decomposed: concept and definition, design and development, manufacturing, installation, operation and maintenance and dismantling. These cost structures are additionally subdivided by considering their sub-costs and bearing in mind the main components of the tidal farm: the nacelle, the supporting tidal energy converter structure and the export power system. Furthermore, a technical study is developed in order to obtain an estimation of the annual energy produced (and, consequently, the incomes generated if the electric tariff is known by considering its principal attributes: the characteristics of the current, the ability of the device to capture energy and its ability to convert and export the energy. The methodology has been applied (together with a sensibility analysis to the particular case of a farm composed of first generation tidal energy converters in one of the Channel Island Races, the Alderney Race, in the U.K., and the results have been attained by means of the computation of engineering indexes, such as the net present value, the internal rate of return, the discounted payback period and the levelized cost of energy, which indicate that the proposed project is economically viable for all the case studies.

  20. Tidal Energy: The benthic effects of an operational tidal stream turbine. (United States)

    O'Carroll, J P J; Kennedy, R M; Creech, A; Savidge, G


    The effect of modified flow on epifaunal boulder reef communities adjacent to the SeaGen, the world's first grid-compliant tidal stream turbine, were assessed. The wake of the SeaGen was modelled and the outputs were used in conjunction with positional and substrate descriptor variables, to relate variation in epifaunal community structure to the modified physical environment. An Artificial Neural Network (ANN) and Generalised Linear Model (GLM) were used to make predictions on the distribution of Ecological Status (ES) of epifaunal communities in relation to the turbulent wake of the SeaGen. ES was assigned using the High Energy Hard Substrate (HEHS) index. ES was largely High throughout the survey area and it was not possible to make predictions on the spatial distribution of ES using an ANN or GLM. Spatial pattern in epifaunal community structure was detected when the study area was partitioned into three treatment areas: area D1; within one rotor diameter (16 m) of the centre of SeaGen, area D2; between one and three rotor diameters, and area D3; outside of three rotor diameters. Area D1 was found to be significantly more variable than D2 and D3 in terms of epifaunal community structure, bare rock distributions and ES. Copyright © 2017 Elsevier Ltd. All rights reserved.