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Sample records for ve tidal volume

  1. Prehospital tidal volume influences hospital tidal volume: A cohort study.

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    Stoltze, Andrew J; Wong, Terrence S; Harland, Karisa K; Ahmed, Azeemuddin; Fuller, Brian M; Mohr, Nicholas M

    2015-06-01

    The purposes of the study are to describe current practice of ventilation in a modern air medical system and to measure the association of ventilation strategy with subsequent ventilator care and acute respiratory distress syndrome (ARDS). Retrospective observational cohort study of intubated adult patients (n = 235) transported by a university-affiliated air medical transport service to a 711-bed tertiary academic center between July 2011 and May 2013. Low tidal volume ventilation was defined as tidal volumes less than or equal to 8 mL/kg predicted body weight. Multivariable regression was used to measure the association between prehospital tidal volume, hospital ventilation strategy, and ARDS. Most patients (57%) were ventilated solely with bag valve ventilation during transport. Mean tidal volume of mechanically ventilated patients was 8.6 mL/kg predicted body weight (SD, 0.2 mL/kg). Low tidal volume ventilation was used in 13% of patients. Patients receiving low tidal volume ventilation during air medical transport were more likely to receive low tidal volume ventilation in the emergency department (P tidal volume (P = .840). Low tidal volume ventilation was rare during air medical transport. Air transport ventilation strategy influenced subsequent ventilation but was not associated with ARDS. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Inspiratory time and tidal volume during intermittent positive pressure ventilation.

    OpenAIRE

    Field, D; Milner, A D; Hopkin, I E

    1985-01-01

    We measured the tidal volume achieved during intermittent positive pressure ventilation using various inspiratory times with a minimum of 0.2 seconds. Results indicate that tidal volume shows no reduction with inspiratory times down to 0.4 seconds. An inspiratory time of 0.3 seconds, however, is likely to reduce tidal volume by 8%, and at 0.2 seconds a 22% fall may be anticipated.

  3. High tidal volume ventilation in infant mice.

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

    2008-06-30

    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.

  4. Fuzzy Control of Tidal volume, Respiration number and Pressure value

    OpenAIRE

    Hasan Guler; Fikret Ata

    2010-01-01

    In this study, control of tidal volume, respiration number and pressure value which are arrived to patient at mechanical ventilator device which is used in intensive care units were performed with fuzzy logic controller. The aim of this system is to reduce workload of aneshesiologist. By calculating tidal volume, respiration number and pressure value, the error Pe(k) between reference pressure value (Pref) and pressure of gas given ill person (Phasta) and error change rate ;#948;Pe(k) were co...

  5. [Evaluation of tidal volume delivered by ventilators during volume-controlled ventilation].

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    Zhou, Juan; Yan, Yong; Cao, Desen

    2014-12-01

    To study the ways which ensure the delivery of enough tidal volume to patients under various conditions close to the demand of the physician. The volume control ventilation model was chosen, and the simulation lung type was active servo lung ASL 5000 or Michigan lung 1601. The air resistance, air compliance and lung type in simulation lungs were set. The tidal volume was obtained from flow analyzer PF 300. At the same tidal volume, the displaying values of tidal volume of E5, Servo i, Evital 4, and Evital XL ventilators with different lung types of patient, compliance of gas piping, leakage, gas types, etc. were evaluated. With the same setting tidal volume of a same ventilator, the tidal volume delivered to patients was different with different lung types of patient, compliance of gas piping, leakage, gas types, etc. Reducing compliance and increasing resistance of the patient lungs caused high peak airway pressure, the tidal volume was lost in gas piping, and the tidal volume be delivered to the patient lungs was decreased. If the ventilator did not compensate to leakage, the tidal volume delivered to the patient lungs was decreased. When the setting gas type of ventilator did not coincide with that applying to the patient, the tidal volume be delivered to the patient lungs might be different with the setting tidal volume of ventilator. To ensure the delivery of enough tidal volume to patients close to the demand of the physician, containable factors such as the compliance of gas piping, leakage, and gas types should be controlled.

  6. Ultra-protective tidal volume: how low should we go?

    OpenAIRE

    Costa, Eduardo LV; Amato, Marcelo BP

    2013-01-01

    Applying tidal volumes of less than 6 mL/kg might improve lung protection in patients with acute respiratory distress syndrome. In a recent article, Retamal and colleagues showed that such a reduction is feasible with conventional mechanical ventilation and leads to less tidal recruitment and overdistension without causing carbon dioxide retention or auto-positive end-expiratory pressure. However, whether the compensatory increase in the respiratory rate blunts the lung protection remains une...

  7. Do new anesthesia ventilators deliver small tidal volumes accurately during volume-controlled ventilation?

    Science.gov (United States)

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

    2008-05-01

    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

  8. Comparison of actual tidal volume in neonatal lung model volume control ventilation using three ventilators.

    Science.gov (United States)

    Toyama, H; Endo, Y; Ejima, Y; Matsubara, M; Kurosawa, S

    2011-07-01

    In neonates, small changes in tidal volumes (V(T)) may lead to complications. Previous studies have shown a significant difference between ventilator-measured tidal volume and tidal volume delivered (actual V(T)). We evaluated the accuracy of three different ventilators to deliver small V(T) during volume-controlled ventilation. We tested Servo 300, 840 ventilator and Evita 4 Neoflow ventilators with lung models simulating normal and injured neonatal lung compliance models. Gas volume delivered from the ventilator into the test circuit (V(TV)) and actual V(T) to the test lung were measured using Ventrak respiration monitors at set V(T) (30 ml). The gas volume increase of the breathing circuit was then calculated. Tidal volumes of the SV300 and PB840 in both lung models were similar to the set V(T) and the actual tidal volumes in the injured model (20.7 ml and 19.8 ml, respectively) were significantly less than that in the normal model (27.4 ml and 23.4 ml). PB840 with circuit compliance compensation could not improve the actual V(T). V(TV) of the EV4N in the normal and the injured models (37.8 ml and 46.6 ml) were markedly increased compared with set V(T), and actual V(T) were similar to set V(T) in the normal and injured model (30.2 ml and 31.9 ml, respectively). EV4N measuring V(T) close to the lung could match actual V(T) to almost the same value as the set V(T) however the gas volume of the breathing circuit was increased. If an accurate value for the patient's actual V(T) is needed, this V(T) must be measured by a sensor located between the Y-piece and the tracheal tube.

  9. High tidal volume decreases adult respiratory distress syndrome, atelectasis, and ventilator days compared with low tidal volume in pediatric burned patients with inhalation injury.

    Science.gov (United States)

    Sousse, Linda E; Herndon, David N; Andersen, Clark R; Ali, Arham; Benjamin, Nicole C; Granchi, Thomas; Suman, Oscar E; Mlcak, Ronald P

    2015-04-01

    Inhalation injury, which is among the causes of acute lung injury and acute respiratory distress syndrome (ARDS), continues to represent a significant source of mortality in burned patients. Inhalation injury often requires mechanical ventilation, but the ideal tidal volume strategy is not clearly defined in burned pediatric patients. The aim of this study was to determine the effects of low and high tidal volume on the number of ventilator days, ventilation pressures, and incidence of atelectasis, pneumonia, and ARDS in pediatric burned patients with inhalation injury within 1 year post burn injury. From 1986 to 2014, inhalation injury was diagnosed by bronchoscopy in pediatric burned patients (n = 932). Patients were divided into 3 groups: unventilated (n = 241), high tidal volume (HTV, 15 ± 3 mL/kg, n = 190), and low tidal volume (LTV, 9 ± 3 mL/kg, n = 501). High tidal volume was associated with significantly decreased ventilator days (p tidal volume significantly decreases ventilator days and the incidence of both atelectasis and ARDS compared with low tidal volume in pediatric burned patients with inhalation injury. Therefore, the use of HTV may interrupt sequences leading to lung injury in our patient population. Copyright © 2015 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  10. Low Tidal Volume Reduces Lung Inflammation Induced by Liquid Ventilation in Piglets With Severe Lung Injury.

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

    2017-05-01

    Total liquid ventilation (TLV) is an alternative treatment for severe lung injury. High tidal volume is usually required for TLV to maintain adequate CO 2 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 CO 2 removal was applied in low tidal volume group to improve CO 2 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, PaO 2 , and PaCO 2 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.

  11. Change in tidal volume during cardiopulmonary resuscitation in newborn piglets.

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    Li, Elliott S; Cheung, Po-Yin; O'Reilly, Megan; Schmölzer, Georg M

    2015-11-01

    The purpose of inflations during cardiopulmonary resuscitation (CPR) is to deliver an adequate tidal volume (VT) to facilitate gas exchange. However, no study has examined VT delivery during chest compression (CC) in detail to understand the effect of CC on lung aeration. The aim of the study was to examine VT changes during CC and their effect on lung aeration. Piglets were anaesthetised, instrumented and intubated with zero leak. They were then randomly assigned to CPR using either 3:1 compression:ventilation ratio (C:V) (n=6), continuous CC with asynchronous ventilations (CCaV) (90 CC/min with 30/min asynchronous ventilations) (n=6) or continuous CC superimposed with 30 s sustained inflations (CC+SI) with a CC rate of 120/min (n=5). A respiratory function monitor (NM3, Respironics, Philips, Andover, Massachusetts, USA) was used to continuously measure inspiration tidal volume (VTi) and expirational tidal volume (VTe). ANOVA with Bonferroni post-test were used to compare variables of all three groups. During the inflation in the 3:1 C:V group, the mean (SD) VTi and VTe was 23.5 (5.3) mL/kg and 19.4 (2.7) mL/kg (p=0.16), respectively. During the CC, we observed a significant VT loss in the 3:1 group with VTi and VTe being 4.1 (1.2) mL/kg and 11.1 (3.3) mL/kg (p=0.007), respectively. In the CCaV group, VTe was higher compared with VTi, but this was not significant. In the CC+SI group, a VT gain during each CC with VTi and VTe of 16.3 (3.2) mL/kg and 14 (3) mL/kg (p=0.21), respectively, was observed. VT delivery is improved using CC+SI compared with 3:1 C:V. This improvement in VT delivery may lead to better alveolar oxygen delivery and lung aeration. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  12. High initial tidal volumes in emergency department patients at risk for acute respiratory distress syndrome.

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    Allison, Michael G; Scott, Michael C; Hu, Kami M; Witting, Michael D; Winters, Michael E

    2015-04-01

    Emergency department (ED) patients are at high risk for the acute respiratory distress syndrome (ARDS). Settings only 1 mL/kg above recommended tidal volumes confers harm for these patients. The purpose of this study was to determine whether ED physicians routinely initiate mechanical ventilation with low tidal volumes in patients at risk for ARDS. We retrospectively reviewed the charts of all adult patients who were intubated in an urban, academic ED. The charts were analyzed to identify patients in whom ARDS developed within 48 hours after ED admission. Patients were eligible for inclusion if they had bilateral infiltrates on imaging, had a Pao2/Fio2 ratio less than 300 mm Hg and did not have heart failure contributing to their presentation. The tidal volumes set in the ED were then compared with the recommended tidal volume of 6 mL/kg of predicted body weight. The initial tidal volumes set in the ED were higher than recommended by an average of 80 mL (95% confidence interval, 60-110, P tidal volume ventilation setting. In an academic, tertiary hospital, newly intubated ED patients in whom ARDS developed within 48 hours after intubation were ventilated with tidal volumes that exceeded recommendations by an average of 1.5 mL/kg. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation.

    Science.gov (United States)

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] The aim of this study was to clarify physical parameters affecting the tidal volume during expiratory abdominal compression in patients with prolonged tracheostomy mechanical ventilation. [Methods] Eighteen patients with prolonged mechanical ventilation were included in this study. Expiratory abdominal compression was performed on patients lying in a supine position. The abdomen above the navel was vertically compressed in synchronization with expiration and released with inspiration. We measured the tidal volume during expiratory abdominal compression. [Results] The mean tidal volume during expiratory abdominal compression was higher than that at rest (430.6 ± 127.1 mL vs. 344.0 ± 94.3 mL). The tidal volume during expiratory abdominal compression was correlated with weight, days of ventilator support, dynamic compliance and abdominal expansion. Stepwise multiple regression analysis revealed that weight (β = 0.499), dynamic compliance (β = 0.387), and abdominal expansion (β = 0.365) were factors contributing to the tidal volume during expiratory abdominal compression. [Conclusion] Expiratory abdominal compression increased the tidal volume in patients with prolonged tracheostomy mechanical ventilation. The tidal volume during expiratory abdominal compression was influenced by each of the pulmonary conditions and the physical characteristics.

  14. Comparison of Tidal Volumes at the Endotracheal Tube and at the Ventilator.

    Science.gov (United States)

    Kim, Paul; Salazar, Adler; Ross, Patrick A; Newth, Christopher J L; Khemani, Robinder G

    2015-11-01

    Lung protective ventilation for children with acute respiratory distress syndrome requires accurate assessment of tidal volume. Although modern ventilators compensate for ventilator tubing compliance, tidal volume measured at the ventilator may not be accurate, particularly in small children. Although ventilator-specific proximal flow sensors that measure tidal volume at the endotracheal tube have been developed, there is little information regarding their accuracy. We sought to test the accuracy of ventilator measured tidal volume with and without proximal flow sensors against a calibrated pneumotachometer in children. Prospective, observational. Tertiary care PICU. Fifty-one endotracheally intubated and mechanically ventilated children younger than 18 years. Tidal volumes were measured at the ventilator, using a ventilator-specific flow sensor, and a calibrated pneumotachometer connected to the SensorMedics 2600A Pediatric Pulmonary Function Cart. In a pressure control mode of ventilation: median tidal volume measured with the pneumotachometer (9.5 mL/kg [interquartile range, 8.2-11.7 mL/kg]) was significantly higher than tidal volume measured either at the ventilator (8.2 mL/kg [7.1-9.6 mL/kg]) or at the proximal flow sensor (8.1 mL/kg [7.2-10.0 mL/kg]) (p tidal volume measured with the pneumotachometer (10.2 mL/kg [8.8-12.4 mL/kg]) was significantly higher than tidal volume measured either at the ventilator (8.0 mL/kg [7.1-9.7 mL/kg]) or at the proximal flow sensor (8.5 mL/kg [7.3-10.4 mL/kg]) (p Tidal volume measured either at the endotracheal tube with a proximal flow sensor or at the ventilator with compensation for tubing compliance are both significantly lower than tidal volume measured with a calibrated pneumotachometer. This underestimation of delivered tidal volume may be particularly important when managing children with acute respiratory distress syndrome.

  15. Failure of Noninvasive Ventilation for De Novo Acute Hypoxemic Respiratory Failure: Role of Tidal Volume.

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    Carteaux, Guillaume; Millán-Guilarte, Teresa; De Prost, Nicolas; Razazi, Keyvan; Abid, Shariq; Thille, Arnaud W; Schortgen, Frédérique; Brochard, Laurent; Brun-Buisson, Christian; Mekontso Dessap, Armand

    2016-02-01

    A low or moderate expired tidal volume can be difficult to achieve during noninvasive ventilation for de novo acute hypoxemic respiratory failure (i.e., not due to exacerbation of chronic lung disease or cardiac failure). We assessed expired tidal volume and its association with noninvasive ventilation outcome. Prospective observational study. Twenty-four bed university medical ICU. Consecutive patients receiving noninvasive ventilation for acute hypoxemic respiratory failure between August 2010 and February 2013. Noninvasive ventilation was uniformly delivered using a simple algorithm targeting the expired tidal volume between 6 and 8 mL/kg of predicted body weight. Expired tidal volume was averaged and respiratory and hemodynamic variables were systematically recorded at each noninvasive ventilation session. Sixty-two patients were enrolled, including 47 meeting criteria for acute respiratory distress syndrome, and 32 failed noninvasive ventilation (51%). Pneumonia (n = 51, 82%) was the main etiology of acute hypoxemic respiratory failure. The median (interquartile range) expired tidal volume averaged over all noninvasive ventilation sessions (mean expired tidal volume) was 9.8 mL/kg predicted body weight (8.1-11.1 mL/kg predicted body weight). The mean expired tidal volume was significantly higher in patients who failed noninvasive ventilation as compared with those who succeeded (10.6 mL/kg predicted body weight [9.6-12.0] vs 8.5 mL/kg predicted body weight [7.6-10.2]; p = 0.001), and expired tidal volume was independently associated with noninvasive ventilation failure in multivariate analysis. This effect was mainly driven by patients with PaO2/FIO2 up to 200 mm Hg. In these patients, the expired tidal volume above 9.5 mL/kg predicted body weight predicted noninvasive ventilation failure with a sensitivity of 82% and a specificity of 87%. A low expired tidal volume is almost impossible to achieve in the majority of patients receiving noninvasive ventilation

  16. Lung protection: an intervention for tidal volume reduction in a teaching intensive care unit

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    Briva, Arturo; Gaiero, Cristina

    2016-01-01

    Objective To determine the effect of feedback and education regarding the use of predicted body weight to adjust tidal volume in a lung-protective mechanical ventilation strategy. Methods The study was performed from October 2014 to November 2015 (12 months) in a single university polyvalent intensive care unit. We developed a combined intervention (education and feedback), placing particular attention on the importance of adjusting tidal volumes to predicted body weight bedside. In parallel, predicted body weight was estimated from knee height and included in clinical charts. Results One hundred fifty-nine patients were included. Predicted body weight assessed by knee height instead of visual evaluation revealed that the delivered tidal volume was significantly higher than predicted. After the inclusion of predicted body weight, we observed a sustained reduction in delivered tidal volume from a mean (standard error) of 8.97 ± 0.32 to 7.49 ± 0.19mL/kg (p < 0.002). Furthermore, the protocol adherence was subsequently sustained for 12 months (delivered tidal volume 7.49 ± 0.54 versus 7.62 ± 0.20mL/kg; p = 0.103). Conclusion The lack of a reliable method to estimate the predicted body weight is a significant impairment for the application of a worldwide standard of care during mechanical ventilation. A combined intervention based on education and repeated feedbacks promoted sustained tidal volume education during the study period (12 months). PMID:27925055

  17. Timing of low tidal volume ventilation and intensive care unit mortality in acute respiratory distress syndrome. A prospective cohort study.

    Science.gov (United States)

    Needham, Dale M; Yang, Ting; Dinglas, Victor D; Mendez-Tellez, Pedro A; Shanholtz, Carl; Sevransky, Jonathan E; Brower, Roy G; Pronovost, Peter J; Colantuoni, Elizabeth

    2015-01-15

    Reducing tidal volume decreases mortality in acute respiratory distress syndrome (ARDS). However, the effect of the timing of low tidal volume ventilation is not well understood. To evaluate the association of intensive care unit (ICU) mortality with initial tidal volume and with tidal volume change over time. Multivariable, time-varying Cox regression analysis of a multisite, prospective study of 482 patients with ARDS with 11,558 twice-daily tidal volume assessments (evaluated in milliliter per kilogram of predicted body weight [PBW]) and daily assessment of other mortality predictors. An increase of 1 ml/kg PBW in initial tidal volume was associated with a 23% increase in ICU mortality risk (adjusted hazard ratio, 1.23; 95% confidence interval [CI], 1.06-1.44; P = 0.008). Moreover, a 1 ml/kg PBW increase in subsequent tidal volumes compared with the initial tidal volume was associated with a 15% increase in mortality risk (adjusted hazard ratio, 1.15; 95% CI, 1.02-1.29; P = 0.019). Compared with a prototypical patient receiving 8 days with a tidal volume of 6 ml/kg PBW, the absolute increase in ICU mortality (95% CI) of receiving 10 and 8 ml/kg PBW, respectively, across all 8 days was 7.2% (3.0-13.0%) and 2.7% (1.2-4.6%). In scenarios with variation in tidal volume over the 8-day period, mortality was higher when a larger volume was used earlier. Higher tidal volumes shortly after ARDS onset were associated with a greater risk of ICU mortality compared with subsequent tidal volumes. Timely recognition of ARDS and adherence to low tidal volume ventilation is important for reducing mortality. Clinical trial registered with www.clinicaltrials.gov (NCT 00300248).

  18. Effects of different tidal volumes in pulmonary and extrapulmonary lung injury with or without intraabdominal hypertension.

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    Santos, Cíntia L; Moraes, Lillian; Santos, Raquel S; Oliveira, Mariana G; Silva, Johnatas D; Maron-Gutierrez, Tatiana; Ornellas, Débora S; Morales, Marcelo M; Capelozzi, Vera L; Jamel, Nelson; Pelosi, Paolo; Rocco, Patricia R M; Garcia, Cristiane S N B

    2012-03-01

    We hypothesized that: (1) intraabdominal hypertension increases pulmonary inflammatory and fibrogenic responses in acute lung injury (ALI); (2) in the presence of intraabdominal hypertension, higher tidal volume reduces lung damage in extrapulmonary ALI, but not in pulmonary ALI. Wistar rats were randomly allocated to receive Escherichia coli lipopolysaccharide intratracheally (pulmonary ALI) or intraperitoneally (extrapulmonary ALI). After 24 h, animals were randomized into subgroups without or with intraabdominal hypertension (15 mmHg) and ventilated with positive end expiratory pressure = 5 cmH(2)O and tidal volume of 6 or 10 ml/kg during 1 h. Lung and chest wall mechanics, arterial blood gases, lung and distal organ histology, and interleukin (IL)-1β, IL-6, caspase-3 and type III procollagen (PCIII) mRNA expressions in lung tissue were analyzed. With intraabdominal hypertension, (1) chest-wall static elastance increased, and PCIII, IL-1β, IL-6, and caspase-3 expressions were more pronounced than in animals with normal intraabdominal pressure in both ALI groups; (2) in extrapulmonary ALI, higher tidal volume was associated with decreased atelectasis, and lower IL-6 and caspase-3 expressions; (3) in pulmonary ALI, higher tidal volume led to higher IL-6 expression; and (4) in pulmonary ALI, liver, kidney, and villi cell apoptosis was increased, but not affected by tidal volume. Intraabdominal hypertension increased inflammation and fibrogenesis in the lung independent of ALI etiology. In extrapulmonary ALI associated with intraabdominal hypertension, higher tidal volume improved lung morphometry with lower inflammation in lung tissue. Conversely, in pulmonary ALI associated with intraabdominal hypertension, higher tidal volume increased IL-6 expression.

  19. Generation of tidal volume via gentle chest pressure in children over one year old.

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    Tsui, Ban C H; Horne, Sara; Tsui, Jenkin; Corry, Gareth N

    2015-07-01

    In the event of cardiac arrest, cardiopulmonary resuscitation (CPR) is a well-established technique to maintain oxygenation of tissues and organs until medical equipment and staff are available. During CPR, chest compressions help circulate blood and have been shown in animal models to be a means of short-term oxygenation. In this study, we tested whether gentle chest pressure can generate meaningful tidal volume in paediatric subjects. This prospective cohort pilot study recruited children under the age of 17 years and undergoing any surgery requiring general anaesthetic and endotracheal intubation. After induction of general anaesthesia, tidal volumes were obtained before and after intubation by applying a downward force on the chest which was not greater than the patient's weight. Mean tidal volumes were compared for unprotected versus protected airway and for type of surgery. Mean tidal volume generated with an unprotected and protected airway was 2.7 (1.7) and 2.9 (2.3) mL/kg, respectively. Mean tidal volume generated with mechanical ventilation was 13.6 (4.9) mL/kg. No statistical significance was found when comparing tidal volumes generated with an unprotected or protected airway (p = 0.20), type of surgery (tonsillectomy and/or adenoidectomy versus other surgery) (unprotected, p = 0.09; protected, p = 0.37), and when age difference between groups was taken into account (p = 0.34). Using gentle chest pressure, we were able to generate over 20% of the tidal volume achieved with mechanical ventilation. Our results suggest that gentle chest pressure may be a means to support temporary airflow in children. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. Monitoring tidal volumes in preterm infants at birth: mask versus endotracheal ventilation.

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    van Vonderen, Jeroen J; Hooper, Stuart B; Krabbe, Vera B; Siew, Melissa L; Te Pas, Arjan B

    2015-01-01

    Upper airway distention during mask ventilation could reduce gas volumes entering the lung compared with ventilation via an endotracheal tube. Therefore, respiratory tract volumes were measured in lambs and tidal volumes were compared in preterm infants before and after intubation. In seven preterm lambs, volumes of the airways (oropharynx, trachea, lungs) were assessed. In 10 preterm infants, delta pressures, tidal volumes and leak were measured during ventilation 2 min before (mask ventilation) and 2 min after intubation (endotracheal ventilation). Inflations coinciding with breaths were excluded. Amount of upper airway distention in lambs and differences in inspiratory and expiratory tidal volume before and after intubation. In lambs, the combined trachea and oropharynx contributed to 14 (12-21) % (median (IQR), whereas the oropharynx contributed to 9 (7-10) % of the total tidal volume measured at the mouth. In preterm infants, inspiratory (11.1 (7.9-22.6) mL/kg vs 5.8 (3.9-9.6) mL/kg (p=0.01)) and expiratory (8.3 (6.8-15.4) mL/kg vs 4.9 (3.9-9.6) mL/kg (p=0.02)) tidal volumes were significantly larger during mask ventilation compared with endotracheal ventilation. Leak was 18.7 (3.3-28.7) % before versus 0 (0-2.3) % after intubation (p0.05). During mask ventilation, expiratory tidal volume increased from 10.0 (5.4-15.6) mL/kg to 11.3 (7.6-17.0) mL/kg (p=0.01), but remained unchanged during endotracheal ventilation. During neonatal mask ventilation, distention of the upper respiratory tract contributes to the tidal volumes measured and should be taken into account when targeting tidal volumes during mask ventilation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  1. Delivery of tidal volume from four anaesthesia ventilators during volume-controlled ventilation: a bench study.

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    Wallon, G; Bonnet, A; Guérin, C

    2013-06-01

    Tidal volume (V(T)) must be accurately delivered by anaesthesia ventilators in the volume-controlled ventilation mode in order for lung protective ventilation to be effective. However, the impact of fresh gas flow (FGF) and lung mechanics on delivery of V(T) by the newest anaesthesia ventilators has not been reported. We measured delivered V(T) (V(TI)) from four anaesthesia ventilators (Aisys™, Flow-i™, Primus™, and Zeus™) on a pneumatic test lung set with three combinations of lung compliance (C, ml cm H2O(-1)) and resistance (R, cm H2O litre(-1) s(-2)): C60R5, C30R5, C60R20. For each CR, three FGF rates (0.5, 3, 10 litre min(-1)) were investigated at three set V(T)s (300, 500, 800 ml) and two values of PEEP (0 and 10 cm H2O). The volume error = [(V(TI) - V(Tset))/V(Tset)] ×100 was computed in body temperature and pressure-saturated conditions and compared using analysis of variance. For each CR and each set V(T), the absolute value of the volume error significantly declined from Aisys™ to Flow-i™, Zeus™, and Primus™. For C60R5, these values were 12.5% for Aisys™, 5% for Flow-i™ and Zeus™, and 0% for Primus™. With an increase in FGF, absolute values of the volume error increased only for Aisys™ and Zeus™. However, in C30R5, the volume error was minimal at mid-FGF for Aisys™. The results were similar at PEEP 10 cm H2O. Under experimental conditions, the volume error differed significantly between the four new anaesthesia ventilators tested and was influenced by FGF, although this effect may not be clinically relevant.

  2. Measurement of tidal volume using respiratory ultrasonic plethysmography in anaesthetized, mechanically ventilated horses.

    Science.gov (United States)

    Russold, Elena; Ambrisko, Tamas D; Schramel, Johannes P; Auer, Ulrike; Van Den Hoven, Rene; Moens, Yves P

    2013-01-01

    To compare tidal volume estimations obtained from Respiratory Ultrasonic Plethysmography (RUP) with simultaneous spirometric measurements in anaesthetized, mechanically ventilated horses. Prospective randomized experimental study. Five experimental horses. Five horses were anaesthetized twice (1 week apart) in random order in lateral and in dorsal recumbency. Nine ventilation modes (treatments) were scheduled in random order (each lasting 4 minutes) applying combinations of different tidal volumes (8, 10, 12 mL kg(-1)) and positive end-expiratory pressures (PEEP) (0, 10, 20 cm H(2)O). Baseline ventilation mode (tidal volume=15 mL kg(-1), PEEP=0 cm H(2)O) was applied for 4 minutes between all treatments. Spirometry and RUP data were downloaded to personal computers. Linear regression analyses (RUP versus spirometric tidal volume) were performed using different subsets of data. Additonally RUP was calibrated against spirometry using a regression equation for all RUP signal values (thoracic, abdominal and combined) with all data collectively and also by an individually determined best regression equation (highest R(2)) for each experiment (horse versus recumbency) separately. Agreement between methods was assessed with Bland-Altman analyses. The highest correlation of RUP and spirometric tidal volume (R(2)=0.81) was found with the combined RUP signal in horses in lateral recumbency and ventilated without PEEP. The bias ±2 SD was 0±2.66 L when RUP was calibrated for collective data, but decreased to 0±0.87 L when RUP was calibrated with individual data. A possible use of RUP for tidal volume measurement during IPPV needs individual calibration to obtain limits of agreement within ±20%. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

  3. Tidal volume in acute respiratory distress syndrome: how best to select it.

    Science.gov (United States)

    Umbrello, Michele; Marino, Antonella; Chiumello, Davide

    2017-07-01

    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 (ECCO 2 R) 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.

  4. 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

    2007-01-01

    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 insulin...

  5. Adaptive support ventilation: A translational study evaluating the size of delivered tidal volumes

    NARCIS (Netherlands)

    Veelo, Denise P.; Dongelmans, Dave A.; Binnekade, Jan M.; Paulus, Frederique; Schultz, Marcus J.

    2010-01-01

    Purpose: Adaptive support ventilation (ASV) is a microprocessor-controlled, closed-loop mode of mechanical ventilation that adapts respiratory rates and tidal volumes (V(T)s) based on the Otis least work of breathing formula. We studied calculated V(T)s in a computer simulation model, and V(T)s

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

    Directory of Open Access Journals (Sweden)

    Fernandez-Bustamante Ana

    2011-11-01

    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

  7. Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury.

    Science.gov (United States)

    Cherpanath, Thomas G V; Smeding, Lonneke; Hirsch, Alexander; Lagrand, Wim K; Schultz, Marcus J; Groeneveld, A B Johan

    2015-10-07

    High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury. Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function. Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p tidal volume ventilation without LPS (p = 0.223). A significant interaction (p tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment. Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well.

  8. Determining volume sensitive waters in Beaufort County, SC tidal creeks

    Science.gov (United States)

    Andrew Tweel; Denise Sanger; Anne Blair; John Leffler

    2016-01-01

    Non-point source pollution from stormwater runoff associated with large-scale land use changes threatens the integrity of ecologically and economically valuable estuarine ecosystems. Beaufort County, SC implemented volume-based stormwater regulations on the rationale that if volume discharge is controlled, contaminant loading will also be controlled.

  9. Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

    Science.gov (United States)

    Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

    2002-09-01

    Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore

  10. High volume tidal or current flow harnessing system

    Energy Technology Data Exchange (ETDEWEB)

    Gorlov, A.M.

    1984-08-07

    Apparatus permitting the utilization of large volumes of water in the harnessing and extracting of a portion of the power generated by the rise and fall of ocean tides, ocean currents, or flowing rivers includes the provision of a dam, and a specialized single cavity chamber of limited size as compared with the water head enclosed by the dam, and an extremely high volume gating system in which all or nearly all of the water between the high and low levels on either side of the dam is cyclically gated through the single chamber from one side of the dam to the other so as to alternately provide positive air pressure and a partial vacuum within the single chamber. In one embodiment, the specialized chamber has a barrier at the bottom which divides the bottom of the chamber in half, large ports at the bottom of the chamber to permit inflow and outflow of high volumes of water, and ganged structures having a higher total area than that of corresponding ports, in which the structures form sluice gates to selectively seal off and open different sets of ports. In another embodiment, a single chamber is used without a barrier. In this embodiment, vertical sluice gates are used which may be activated automatically by pressures acting on the sluice gates as a result of ingested and expelled water.

  11. Effects of inhalational anaesthesia with low tidal volume ventilation on end-tidal sevoflurane and carbon dioxide concentrations: prospective randomized study.

    Science.gov (United States)

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

    2014-02-01

    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 (Ptidal 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 (Ptidal 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.

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

    International Nuclear Information System (INIS)

    Li Guang; Arora, Naveen C; Xie Huchen; Ning, Holly; Citrin, Deborah; Kaushal, Aradhana; Zach, Leor; Camphausen, Kevin; Miller, Robert W; Lu Wei; Low, Daniel

    2009-01-01

    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 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 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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: ligeorge@mail.nih.gov

    2009-04-07

    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.

  14. Is pulmonary resistance constant, within the range of tidal volume ventilation, in patients with ARDS?

    Science.gov (United States)

    Mols, G; Kessler, V; Benzing, A; Lichtwarck-Aschoff, M; Geiger, K; Guttmann, J

    2001-02-01

    When managing patients with acute respiratory distress syndrome (ARDS), respiratory system compliance is usually considered first and changes in resistance, although recognized, are neglected. Resistance can change considerably between minimum and maximum lung volume, but is generally assumed to be constant in the tidal volume range (V(T)). We measured resistance during tidal ventilation in 16 patients with ARDS or acute lung injury by the slice method and multiple linear regression analysis. Resistance was constant within V(T) in only six of 16 patients. In the remaining patients, resistance decreased, increased or showed complex changes. We conclude that resistance within V(T) varies considerably from patient to patient and that constant resistance within V(T) is not always likely.

  15. Effects of respiratory rate and tidal volume on gas exchange in total liquid ventilation.

    Science.gov (United States)

    Bull, Joseph L; Tredici, Stefano; Fujioka, Hideki; Komori, Eisaku; Grotberg, James B; Hirschl, Ronald B

    2009-01-01

    Using a rabbit model of total liquid ventilation (TLV), and in a corresponding theoretical model, we compared nine tidal volume-respiratory rate combinations to identify a ventilator strategy to maximize gas exchange, while avoiding choked flow, during TLV. Nine different ventilation strategies were tested in each animal (n = 12): low [LR = 2.5 breath/min (bpm)], medium (MR = 5 bpm), or high (HR = 7.5 bpm) respiratory rates were combined with a low (LV = 10 ml/kg), medium (MV = 15 ml/kg), or high (HV = 20 ml/kg) tidal volumes. Blood gases and partial pressures, perfluorocarbon gas content, and airway pressures were measured for each combination. Choked flow occurred in all high respiratory rate-high volume animals, 71% of high respiratory rate-medium volume (HRMV) animals, and 50% of medium respiratory rate-high volume (MRHV) animals but in no other combinations. Medium respiratory rate-medium volume (MRMV) resulted in the highest gas exchange of the combinations that did not induce choke. The HRMV and MRHV animals that did not choke had similar or higher gas exchange than MRMV. The theory predicted this behavior, along with spatial and temporal variations in alveolar gas partial pressures. Of the combinations that did not induce choked flow, MRMV provided the highest gas exchange. Alveolar gas transport is diffusion dominated and rapid during gas ventilation but is convection dominated and slow during TLV. Consequently, the usual alveolar gas equation is not applicable for TLV.

  16. 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

    2005-07-01

    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.

  17. Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation

    OpenAIRE

    Lipes, Jed; Bojmehrani, Azadeh; Lellouche, Francois

    2012-01-01

    Protective ventilation with low tidal volume has been shown to reduce morbidity and mortality in patients suffering from acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is associated with particular clinical challenges and is therefore often underutilized as a therapeutic option in clinical practice. Despite some potential difficulties, data have been published examining the application of protective ventilation in patients without lung inj...

  18. Tidal volume and mortality in mechanically ventilated children: a systematic review and meta-analysis of observational studies*.

    Science.gov (United States)

    de Jager, Pauline; Burgerhof, Johannes G M; van Heerde, Marc; Albers, Marcel J I J; Markhorst, Dick G; Kneyber, Martin C J

    2014-12-01

    To determine whether tidal volume is associated with mortality in critically ill, mechanically ventilated children. MEDLINE, EMBASE, and CINAHL databases from inception until July 2013 and bibliographies of included studies without language restrictions. Randomized clinical trials and observational studies reporting mortality in mechanically ventilated PICU patients. Two authors independently selected studies and extracted data on study methodology, quality, and patient outcomes. Meta-analyses were performed using the Mantel-Haenszel random-effects model. Heterogeneity was quantified using I. Study quality was assessed using the Newcastle-Ottawa Score for cohort studies. Out of 142 citations, seven studies met the inclusion criteria, and additional two articles were identified from references of the found articles. One was excluded. These eight studies included 1,756 patients. Mortality rates ranged from 13% to 42%. There was no association between tidal volume and mortality when tidal volume was dichotomized at 7, 8, 10, or 12 mL/kg. Comparing patients ventilated with tidal volume less than 7 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg and tidal volume less than 8 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg also showed no association between tidal volume and mortality. Limiting the analysis to patients with acute lung injury/acute respiratory distress syndrome did not change these results. Heterogeneity was observed in all pooled analyses. A relationship between tidal volume and mortality in mechanically ventilated children could not be identified, irrespective of the severity of disease. The significant heterogeneity observed in the pooled analyses necessitates future studies in well-defined patient populations to understand the effects of tidal volume on patient outcome.

  19. Accuracy of near-patient vs. inbuilt spirometry for monitoring tidal volumes in an in-vitro paediatric lung model.

    Science.gov (United States)

    Morgenroth, S; Thomas, J; Cannizzaro, V; Weiss, M; Schmidt, A R

    2018-03-01

    Spirometric monitoring provides precise measurement and delivery of tidal volumes within a narrow range, which is essential for lung-protective strategies that aim to reduce morbidity and mortality in mechanically-ventilated patients. Conventional anaesthesia ventilators include inbuilt spirometry to monitor inspiratory and expiratory tidal volumes. The GE Aisys CS 2 anaesthesia ventilator allows additional near-patient spirometry via a sensor interposed between the proximal end of the tracheal tube and the respiratory tubing. Near-patient and inbuilt spirometry of two different GE Aisys CS 2 anaesthesia ventilators were compared in an in-vitro study. Assessments were made of accuracy and variability in inspiratory and expiratory tidal volume measurements during ventilation of six simulated paediatric lung models using the ASL 5000 test lung. A total of 9240 breaths were recorded and analysed. Differences between inspiratory tidal volumes measured with near-patient and inbuilt spirometry were most significant in the newborn setting (p tidal volume measurements with near-patient spirometry were consistently more accurate than with inbuilt spirometry for all lung models (p tidal volumes decreased with increasing tidal volumes, and was smaller with near-patient than with inbuilt spirometry. The variability in measured tidal volumes was higher during expiration, especially with inbuilt spirometry. In conclusion, the present in-vitro study shows that measurements with near-patient spirometry are more accurate and less variable than with inbuilt spirometry. Differences between measurement methods were most significant in the smallest patients. We therefore recommend near-patient spirometry, especially for neonatal and paediatric patients. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

  20. Respiratory Pattern and Tidal Volumes Differ for Pressure Support and Volume-assured Pressure Support in Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Nicholson, Trevor T; Smith, Sean B; Siddique, Teepu; Sufit, Robert; Ajroud-Driss, Senda; Coleman, John M; Wolfe, Lisa F

    2017-07-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease resulting in respiratory failure and death. Use of noninvasive ventilation (NIV) improves survival. However, use of volume-assured pressure support (VAPS) has not been extensively studied in ALS. To explore the clinical usefulness of a detailed evaluation of device-recorded NIV data in the management of chronic respiratory failure in ALS, and to determine whether there are differences in efficacy between patients using VAPS or PS. We performed a retrospective chart review of 271 patients with ALS using either PS or VAPS, along with an evaluation of device-recorded data to explore differences in attainment of goal tidal volumes (Vt) and ratio of respiratory rate to tidal volume (f/Vt), in addition to triggering and cycling ability. Two hundred and fifteen patients were using PS, while 56 were using VAPS. There were no significant differences in demographic data, symptoms, pulmonary function, or patient compliance. Compared with VAPS, achieved Vt was significantly lower for PS while f/Vt was significantly higher. Percent spontaneous triggering was relatively preserved in both cohorts, whereas percent spontaneous cycling was considerably decreased in both. Furthermore, there was no association found between spontaneous triggering or cycling, and pulmonary function, indicating the presence of low spontaneous breath cycling or triggering ability is difficult to predict. Examination of device data for exhaled tidal volumes and f/Vt may be of use in evaluating efficacy of NIV in ALS. VAPS provides more reliable goal Vt than does PS, and is associated with decreased f/Vt. Spontaneous cycling is decreased in ALS despite preservation of triggering ability. Although a set backup rate may address decreased triggering, perhaps more importantly, setting a sufficient fixed inspiratory time would address the issue of decreased cycling.

  1. Tidal volume estimation using the blanket fractal dimension of the tracheal sounds acquired by smartphone.

    Science.gov (United States)

    Reljin, Natasa; Reyes, Bersain A; Chon, Ki H

    2015-04-27

    In this paper, we propose the use of blanket fractal dimension (BFD) to estimate the tidal volume from smartphone-acquired tracheal sounds. We collected tracheal sounds with a Samsung Galaxy S4 smartphone, from five (N = 5) healthy volunteers. Each volunteer performed the experiment six times; first to obtain linear and exponential fitting models, and then to fit new data onto the existing models. Thus, the total number of recordings was 30. The estimated volumes were compared to the true values, obtained with a Respitrace system, which was considered as a reference. Since Shannon entropy (SE) is frequently used as a feature in tracheal sound analyses, we estimated the tidal volume from the same sounds by using SE as well. The evaluation of the performed estimation, using BFD and SE methods, was quantified by the normalized root-mean-squared error (NRMSE). The results show that the BFD outperformed the SE (at least twice smaller NRMSE was obtained). The smallest NRMSE error of 15.877% ± 9.246% (mean ± standard deviation) was obtained with the BFD and exponential model. In addition, it was shown that the fitting curves calculated during the first day of experiments could be successfully used for at least the five following days.

  2. Tidal Volume Estimation Using the Blanket Fractal Dimension of the Tracheal Sounds Acquired by Smartphone

    Directory of Open Access Journals (Sweden)

    Natasa Reljin

    2015-04-01

    Full Text Available In this paper, we propose the use of blanket fractal dimension (BFD to estimate the tidal volume from smartphone-acquired tracheal sounds. We collected tracheal sounds with a Samsung Galaxy S4 smartphone, from five (N = 5 healthy volunteers. Each volunteer performed the experiment six times; first to obtain linear and exponential fitting models, and then to fit new data onto the existing models. Thus, the total number of recordings was 30. The estimated volumes were compared to the true values, obtained with a Respitrace system, which was considered as a reference. Since Shannon entropy (SE is frequently used as a feature in tracheal sound analyses, we estimated the tidal volume from the same sounds by using SE as well. The evaluation of the performed estimation, using BFD and SE methods, was quantified by the normalized root-mean-squared error (NRMSE. The results show that the BFD outperformed the SE (at least twice smaller NRMSE was obtained. The smallest NRMSE error of 15.877% ± 9.246% (mean ± standard deviation was obtained with the BFD and exponential model. In addition, it was shown that the fitting curves calculated during the first day of experiments could be successfully used for at least the five following days.

  3. Utilizing Forced Vital Capacity to Predict Low Lung Compliance and Select Intraoperative Tidal Volume During Thoracic Surgery.

    Science.gov (United States)

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

    2017-12-01

    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

  4. Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation

    Directory of Open Access Journals (Sweden)

    Jed Lipes

    2012-01-01

    Full Text Available Protective ventilation with low tidal volume has been shown to reduce morbidity and mortality in patients suffering from acute lung injury (ALI and acute respiratory distress syndrome (ARDS. Low tidal volume ventilation is associated with particular clinical challenges and is therefore often underutilized as a therapeutic option in clinical practice. Despite some potential difficulties, data have been published examining the application of protective ventilation in patients without lung injury. We will briefly review the physiologic rationale for low tidal volume ventilation and explore the current evidence for protective ventilation in patients without lung injury. In addition, we will explore some of the potential reasons for its underuse and provide strategies to overcome some of the associated clinical challenges.

  5. Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation

    Science.gov (United States)

    Lipes, Jed; Bojmehrani, Azadeh; Lellouche, Francois

    2012-01-01

    Protective ventilation with low tidal volume has been shown to reduce morbidity and mortality in patients suffering from acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is associated with particular clinical challenges and is therefore often underutilized as a therapeutic option in clinical practice. Despite some potential difficulties, data have been published examining the application of protective ventilation in patients without lung injury. We will briefly review the physiologic rationale for low tidal volume ventilation and explore the current evidence for protective ventilation in patients without lung injury. In addition, we will explore some of the potential reasons for its underuse and provide strategies to overcome some of the associated clinical challenges. PMID:22536499

  6. Breathing circuit compliance and accuracy of displayed tidal volume during pressure-controlled ventilation of infants: A quality improvement project.

    Science.gov (United States)

    Glenski, Todd A; Diehl, Carrie; Clopton, Rachel G; Friesen, Robert H

    2017-09-01

    Anesthesia machines have evolved to deliver desired tidal volumes more accurately by measuring breathing circuit compliance during a preuse self-test and then incorporating the compliance value when calculating expired tidal volume. The initial compliance value is utilized in tidal volume calculation regardless of whether the actual compliance of the breathing circuit changes during a case, as happens when corrugated circuit tubing is manually expanded after the preuse self-test but before patient use. We noticed that the anesthesia machine preuse self-test was usually performed on nonexpanded pediatric circuit tubing, and then the breathing circuit was subsequently expanded for clinical use. We aimed to demonstrate that performing the preuse self-test in that manner could lead to incorrectly displayed tidal volume on the anesthesia machine monitor. The goal of this quality improvement project was to change the usual practice and improve the accuracy of displayed tidal volume in infants undergoing general anesthesia. There were four stages of the project: (i) gathering baseline data about the performance of the preuse self-test and using infant and adult test lungs to measure discrepancies of displayed tidal volumes when breathing circuit compliance was changed after the initial preuse self-test; (ii) gathering clinical data during pressure-controlled ventilation comparing anesthesia machine displayed tidal volume with actual spirometry tidal volume in patients less than 10 kg before (machine preuse self-test performed while the breathing circuit was nonexpanded) and after an intervention (machine preuse self-test performed after the breathing circuit was fully expanded); (iii) performing department-wide education to help implement practice change; (iv) gathering postintervention data to determine the prevalence of proper machine preuse self-test. At constant pressure-controlled ventilation through fully expanded circuit tubing, displayed tidal volume was 83

  7. Tidal Volume Single Breath Washout of Two Tracer Gases - A Practical and Promising Lung Function Test

    Science.gov (United States)

    Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

    2011-01-01

    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 (SF6) and helium (He) using an ultrasonic flowmeter (USFM). Methods The tracer gas mixture contained 5% SF6 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 SF6 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 SF6 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 SF6 and He washout patterns during tidal breathing. PMID:21423739

  8. [Characteristics of tidal breathing pulmonary function in children with tracheobronchomalacia].

    Science.gov (United States)

    Li, Lan; Chen, Qaing; Zhang, Fan; Zhu, Shuang-Gui; Hu, Ci-Lang; Wu, Ai-Min

    2017-12-01

    To investigate the characteristics of tidal breathing pulmonary function in children with tracheobronchomalacia (TBM). In this study, 30 children who were diagnosed with TBM using electronic bronchoscopy were enrolled in the observation group; 30 healthy children were recruited in the normal control group. For individuals in each group, the assessment of tidal breath pulmonary function was performed at diagnosis and 3, 6, 9, and 12 months after diagnosis. There were no significant differences in tidal volume, inspiratory time, expiratory time, and inspiratory to expiratory ratio between the two groups (P>0.05). Compared with the control group, the observation group had a significantly higher respiratory rate and significantly lower ratio of time to peak tidal expiratory flow to total expiratory time (TPTEF/TE) and ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE). There was a time-dependent increase in TPTEF/TE and VPTEF/VE for TBM children from the time of initial diagnosis to 12 months after diagnosis. Tidal breathing pulmonary function has characteristic changes in children with TBM. Tidal breathing pulmonary function tends to be recovered with increased age in children with TBM.

  9. A prototype of volume-controlled tidal liquid ventilator using independent piston pumps.

    Science.gov (United States)

    Robert, Raymond; Micheau, Philippe; Cyr, Stéphane; Lesur, Olivier; Praud, Jean-Paul; Walti, Hervé

    2006-01-01

    Liquid ventilation using perfluorochemicals (PFC) offers clear theoretical advantages over gas ventilation, such as decreased lung damage, recruitment of collapsed lung regions, and lavage of inflammatory debris. We present a total liquid ventilator designed to ventilate patients with completely filled lungs with a tidal volume of PFC liquid. The two independent piston pumps are volume controlled and pressure limited. Measurable pumping errors are corrected by a programmed supervisor module, which modifies the inserted or withdrawn volume. Pump independence also allows easy functional residual capacity modifications during ventilation. The bubble gas exchanger is divided into two sections such that the PFC exiting the lungs is not in contact with the PFC entering the lungs. The heating system is incorporated into the metallic base of the gas exchanger, and a heat-sink-type condenser is placed on top of the exchanger to retrieve PFC vapors. The prototype was tested on 5 healthy term newborn lambs (<5 days old). The results demonstrate the efficiency and safety of the prototype in maintaining adequate gas exchange, normal acido-basis equilibrium, and cardiovascular stability during a short, 2-hour total liquid ventilator. Airway pressure, lung volume, and ventilation scheme were maintained in the targeted range.

  10. 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.

    Science.gov (United States)

    Sajedi, Parvin; Abooei, Mohsen; Shafa, Amir; Karbalaei, Mahboobeh; Babaei, Atefeh

    2016-01-01

    The aim of this study was to prevent of increasing end-tidal carbon dioxide (ETCO 2) with changing of vital capacity and respiratory rate when using of birthing filter in infants. 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 CO 2 (PETCO 2 ) 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 ETCO 2 level. In the second and the third groups, respiratory rates and tidal volume had been increased retrospectively, until that ETCO 2 ≤35 mmHg was received. We used ANOVA, Chi-square, and descriptive tests for data analysis. P 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 PETCO 2 level were statistically significant between Group 1 and the other two groups after filter insertion ( P = 0.01 and P = 0.00,1 respectively). With changing the vital capacity and respiratory rate we can control PETCO 2 level ≤35 mmHg during using of birthing filters in infants. We recommend this instrument during anesthesia of infants.

  11. 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.

    2012-01-01

    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

  12. Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model.

    Science.gov (United States)

    Soares, Joao Henrique Neves; Carvalho, Alysson Roncally; Bergamini, Bruno Curty; Gress, Maria Alice Kuster; Jandre, Frederico Caetano; Zin, Walter Araujo; Giannella-Neto, Antonio

    2018-06-01

    We compared respiratory mechanics between the positive end-expiratory pressure of minimal respiratory system elastance (PEEP minErs ) and three levels of PEEP during low-tidal-volume (6 mL/kg) ventilation in rats. Twenty-four rats were anesthetized, paralyzed, and mechanically ventilated. Airway pressure (P aw ), flow (F), and volume (V) were fitted by a linear single compartment model (LSCM) P aw (t) = E rs  × V(t) + R rs  × F(t) + PEEP or a volume- and flow-dependent SCM (VFDSCM) P aw (t) = (E 1  + E 2  × V(t)) × V(t) + (K 1  + K 2  × |F(t)|) × F(t) + PEEP, where E rs and R rs are respiratory system elastance and resistance, respectively; E 1 and E 2 × V are volume-independent and volume-dependent E rs , respectively; and K 1 and K 2  × F are flow-independent and flow-dependent R rs , respectively. Animals were ventilated for 1 h at PEEP 0 cmH 2 O (ZEEP); PEEP minErs ; 2 cmH 2 O above PEEP minErs (PEEP minErs+2 ); or 4 cmH 2 O above PEEP minErs (PEEP minErs+4 ). Alveolar tidal recruitment/derecruitment and overdistension were assessed by the index %E 2  = 100 × [(E 2  × V T )/(E 1  + |E 2 | × V T )], and alveolar stability by the slope of E rs (t). %E 2 varied between 0 and 30% at PEEP minErs in most respiratory cycles. Alveolar Tidal recruitment/derecruitment (%E 2   30) were predominant in the absence of PEEP and in PEEP levels higher than PEEP minErs , respectively. The slope of E rs (t) was different from zero in all groups besides PEEP minErs+4 . PEEP minErs presented the best compromise between alveolar tidal recruitment/derecruitment and overdistension, during 1 h of low-V T mechanical ventilation.

  13. Effects of tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury and acute respiratory distress syndrome.

    Science.gov (United States)

    Kallet, Richard H; Campbell, Andre R; Dicker, Rochelle A; Katz, Jeffrey A; Mackersie, Robert C

    2006-01-01

    To assess the effects of step-changes in tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS). Prospective, nonconsecutive patients with ALI/ARDS. Adult surgical, trauma, and medical intensive care units at a major inner-city, university-affiliated hospital. Ten patients with ALI/ARDS managed clinically with lung-protective ventilation. Five patients were ventilated at a progressively smaller tidal volume in 1 mL/kg steps between 8 and 5 mL/kg; five other patients were ventilated at a progressively larger tidal volume from 5 to 8 mL/kg. The volume mode was used with a flow rate of 75 L/min. Minute ventilation was maintained constant at each tidal volume setting. Afterward, patients were placed on continuous positive airway pressure for 1-2 mins to measure their spontaneous tidal volume. Work of breathing and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100). Work of breathing progressively increased (0.86 +/- 0.32, 1.05 +/- 0.40, 1.22 +/- 0.36, and 1.57 +/- 0.43 J/L) at a tidal volume of 8, 7, 6, and 5 mL/kg, respectively. In nine of ten patients there was a strong negative correlation between work of breathing and the ventilator-to-patient tidal volume difference (R = -.75 to -.998). : The ventilator-delivered tidal volume exerts an independent influence on work of breathing during lung-protective ventilation in patients with ALI/ARDS. Patient work of breathing is inversely related to the difference between the ventilator-delivered tidal volume and patient-generated tidal volume during a brief trial of unassisted breathing.

  14. 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.

    2009-01-01

    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

  15. 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.

    2006-01-01

    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.

  16. Accuracy of tidal volume delivered by home mechanical ventilation during mouthpiece ventilation

    Science.gov (United States)

    Prigent, Helene; Falaize, Line; Leroux, Karl; Santos, Dante; Vaugier, Isabelle; Orlikowski, David; Lofaso, Frederic

    2016-01-01

    The aim of our study was to evaluate efficacy and reliability of currently available ventilators for mouthpiece ventilation (MPV). Five life-support home ventilators were assessed in a bench test using different settings simulating the specificities of MPV, such as intermittent circuit disconnection and presence of continuous leaks. The intermittent disconnection of the circuit caused relevant swings in the delivered tidal volume (VT), showing a VT overshoot during the disconnection periods and a VT decrease when the interface was reconnected to the test lung. The five ventilators showed substantial differences in the number of respiratory cycles necessary to reach a stable VT in the volume-controlled setting, ranging from 1.3 ± 0.6 to 7.3 ± 1.2 cycles. These differences were less accentuated in the volume-assisted setting (MPV-dedicated mode, when available). Our data show large differences in the capacity of the different ventilators to deal with the rapidly changing respiratory load features that characterize MPV, which can be further accentuated according to the used ventilator setting. The dedicated MPV modes allow improvement in the performance of ventilators only in some defined situations. This has practical consequences for the choice of the ventilator to be used for MPV in a specific patient. PMID:27146811

  17. Change in end-tidal carbon dioxide outperforms other surrogates for change in cardiac output during fluid challenge.

    Science.gov (United States)

    Lakhal, K; Nay, M A; Kamel, T; Lortat-Jacob, B; Ehrmann, S; Rozec, B; Boulain, T

    2017-03-01

    During fluid challenge, volume expansion (VE)-induced increase in cardiac output (Δ VE CO) is seldom measured. In patients with shock undergoing strictly controlled mechanical ventilation and receiving VE, we assessed minimally invasive surrogates for Δ VE CO (by transthoracic echocardiography): fluid-induced increases in end-tidal carbon dioxide (Δ VE E'CO2 ); pulse (Δ VE PP), systolic (Δ VE SBP), and mean systemic blood pressure (Δ VE MBP); and femoral artery Doppler flow (Δ VE FemFlow). In the absence of arrhythmia, fluid-induced decrease in heart rate (Δ VE HR) and in pulse pressure respiratory variation (Δ VE PPV) were also evaluated. Areas under the receiver operating characteristic curves (AUC ROC s) reflect the ability to identify a response to VEVE CO ≥15%). In 86 patients, Δ VE E'CO2 had an AUC ROC =0.82 [interquartile range 0.73-0.90], significantly higher than the AUC ROC for Δ VE PP, Δ VE SBP, Δ VE MBP, and Δ VE FemFlow (AUC ROC =0.61-0.65, all P  1 mm Hg (>0.13 kPa) had good positive (5.0 [2.6-9.8]) and fair negative (0.29 [0.2-0.5]) likelihood ratios. The 16 patients with arrhythmia had similar relationships between Δ VE E'CO2 and Δ VE CO to patients with regular rhythm ( r 2 =0.23 in both subgroups). In 60 patients with no arrhythmia, Δ VE E'CO2 (AUC ROC =0.84 [0.72-0.92]) outperformed Δ VE HR (AUC ROC =0.52 [0.39-0.66], P AUC ROC =0.73 [0.60-0.84], P =0.21). In the 45 patients with no arrhythmia and receiving ventilation with tidal volume AUC ROC =0.86 [0.72-0.95] vs 0.66 [0.49-0.80], P =0.02. Δ VE E'CO2 outperformed Δ VE PP, Δ VE SBP, Δ VE MBP, Δ VE FemFlow, and Δ VE HR and, during protective ventilation, arrhythmia, or both, it also outperformed Δ VE PPV. A value of Δ VE E'CO2 >1 mm Hg (>0.13 kPa) indicated a likely response to VE. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  18. Tidal volume delivery from ICU ventilators at BTPS conditions: a bench study.

    Science.gov (United States)

    Duchateau, Paul; Guérin, Claude

    2013-04-01

    Even though it is not a common practice, an external filter to the expiratory limb of the breathing circuit may protect the expiratory valve from water saturation in case of nebulization, or from the environment in case of lung infection with multi-drug-resistant micro-organisms or H1N1 influenza. We added an external filter to the expiratory limb and measured tidal volume (VT) from 6 ICU ventilators: 2 with built-in expiratory filter (Avea, Puritan Bennett 840), and 4 without (Engström Carestation, Evita XL, Evita V500, and Servo-i), set in volume controlled mode, at BTPS (body temperature and pressure saturated) condition, with a heated humidifier and a lung model (compliance 16 mL/cm H2O, resistance 20 cm H2O/L/s) placed inside a neonatal incubator. The temperature was targeted at 37°C for both the heated humidifier and the incubator. The setup was run continuously for 24 hours. In the latter 4 ICU ventilators, a Hygrobac or Sterivent S external filter was placed upstream from the expiratory valve for an additional 24-hour period for each. At the end of this period, VT was measured at 4 nominal VT values (300, 400, 500, and 800 mL) with a pneumotachograph. The volume error computed from the ratio of set to measured VT (% set VT) was the primary end point. In these warm and wet conditions, volume error averaged 96 ± 3% for Avea, 100 ± 7% for Puritan Bennett 840, 90 ± 2% for Evita XL, 100 ± 7% for Evita V500, 105 ± 2% for Servo-i, and 108 ± 4% for Engström Carestation (P ventilators for VT delivery, with further significant changes occurring after addition of a filter at the distal expiratory limb.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Lung and chest wall impedances in the dog: effects of frequency and tidal volume.

    Science.gov (United States)

    Barnas, G M; Stamenović, D; Lutchen, K R; Mackenzie, C F

    1992-01-01

    Dependences of the mechanical properties of the respiratory system on frequency (f) and tidal volume (VT) in the normal ranges of breathing are not clear. We measured, simultaneously and in vivo, resistance and elastance of the total respiratory system (Rrs and Ers), lungs (RL and EL), and chest wall (Rcw and Ecw) of five healthy anesthetized paralyzed dogs during sinusoidal volume oscillations at the trachea (50-300 ml, 0.2-2 Hz) delivered at a constant mean lung volume. Each dog showed the same f and VT dependences. The Ers and Ecw increased with increasing f to 1 Hz and decreased with increasing VT up to 200 ml. Although EL increased slightly with increasing f, it was independent of VT. The Rcw decreased from 0.2 to 2 Hz at all VT and decreased with increasing VT. Although the RL decreased from 0.2 to 0.6 Hz and was independent of VT, at higher f RL tended to increase with increasing f and VT (i.e., as peak flow increased). Finally, the f and VT dependences of Rrs were similar to those of Rcw below 0.6 Hz but mirrored RL at higher f. These data capture the competing influences of airflow nonlinearities vs. tissue nonlinearities on f and VT dependence of the lung, chest wall, and total respiratory system. More specifically, we conclude that 1) VT dependences in Ers and Rrs below 0.6 Hz are due to nonlinearities in chest wall properties, 2) above 0.6 Hz, the flow dependence of airways resistance dominates RL and Rrs, and 3) lung tissue behavior is linear in the normal range of breathing.

  1. Low Tidal Volume versus Non-Volume-Limited Strategies for Patients with Acute Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Walkey, Allan J; Goligher, Ewan C; Del Sorbo, Lorenzo; Hodgson, Carol L; Adhikari, Neill K J; Wunsch, Hannah; Meade, Maureen O; Uleryk, Elizabeth; Hess, Dean; Talmor, Daniel S; Thompson, B Taylor; Brower, Roy G; Fan, Eddy

    2017-10-01

    Trials investigating use of lower tidal volumes and inspiratory pressures for patients with acute respiratory distress syndrome (ARDS) have shown mixed results. To compare clinical outcomes of mechanical ventilation strategies that limit tidal volumes and inspiratory pressures (LTV) to strategies with tidal volumes of 10 to 15 ml/kg among patients with ARDS. This is a systematic review and meta-analysis of clinical trials investigating LTV mechanical ventilation strategies. We used random effects models to evaluate the effect of LTV on 28-day mortality, organ failure, ventilator-free days, barotrauma, oxygenation, and ventilation. Our primary analysis excluded trials for which the LTV strategy was combined with the additional strategy of higher positive end-expiratory pressure (PEEP), but these trials were included in a stratified sensitivity analysis. We performed metaregression of tidal volume gradient achieved between intervention and control groups on mortality effect estimates. We used Grading of Recommendations Assessment, Development, and Evaluation methodology to determine the quality of evidence. Seven randomized trials involving 1,481 patients met eligibility criteria for this review. Mortality was not significantly lower for patients receiving an LTV strategy (33.6%) as compared with control strategies (40.4%) (relative risk [RR], 0.87; 95% confidence interval [CI], 0.70-1.08; heterogeneity statistic I 2  = 46%), nor did an LTV strategy significantly decrease barotrauma or ventilator-free days when compared with a lower PEEP strategy. Quality of evidence for clinical outcomes was downgraded for imprecision. Metaregression showed a significant inverse association between larger tidal volume gradient between LTV and control groups and log odds ratios for mortality (β, -0.1587; P = 0.0022). Sensitivity analysis including trials that protocolized an LTV/high PEEP cointervention showed lower mortality associated with LTV (nine trials and 1

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

    Science.gov (United States)

    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

    2008-01-01

    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 preexisting lung injury. Patients scheduled to undergo an elective surgical procedure (lasting > or = 5 h) were randomly assigned to mechanical ventilation with either higher tidal volumes of 12 ml/kg ideal body weight and no positive end-expiratory pressure (PEEP) or lower tidal volumes of 6 ml/kg and 10 cm H2O PEEP. After induction of anesthesia and 5 h thereafter, bronchoalveolar lavage fluid and/or blood was investigated for polymorphonuclear cell influx, changes in levels of inflammatory markers, and nucleosomes. Mechanical ventilation with lower tidal volumes and PEEP (n = 21) attenuated the increase of pulmonary levels of interleukin (IL)-8, myeloperoxidase, and elastase as seen with higher tidal volumes and no PEEP (n = 19). Only for myeloperoxidase, a difference was found between the two ventilation strategies after 5 h of mechanical ventilation (P volumes and PEEP may limit pulmonary inflammation in mechanically ventilated patients without preexisting lung injury. The specific contribution of both lower tidal volumes and PEEP on the protective effects of the lung should be further investigated.

  3. Influence of tidal volume on ventilation inhomogeneity assessed by electrical impedance tomography during controlled mechanical ventilation

    International Nuclear Information System (INIS)

    Becher, T; Kott, M; Schädler, D; Vogt, B; Meinel, T; Weiler, N; Frerichs, I

    2015-01-01

    The global inhomogeneity (GI) index is a parameter of ventilation inhomogeneity that can be calculated from images of tidal ventilation distribution obtained by electrical impedance tomography (EIT). It has been suggested that the GI index may be useful for individual adjustment of positive end-expiratory pressure (PEEP) and for guidance of ventilator therapy. The aim of the present work was to assess the influence of tidal volume (V_T) on the GI index values. EIT data from 9 patients with acute respiratory distress syndrome ventilated with a low and a high V_T of 5   ±   1 (mean  ±  SD) and 9   ±   1 ml kg"−"1 predicted body weight at a high and a low level of PEEP (PEEP_h_i_g_h, PEEP_l_o_w) were analyzed. PEEP_h_i_g_h and PEEP_l_o_w were set 2 cmH_2O above and 5 cmH_2O below the lower inflection point of a quasi-static pressure volume loop, respectively. The lower inflection point was identified at 8.1   ±   1.4 (mean  ±  SD) cmH_2O, resulting in a PEEP_h_i_g_h of 10.1   ±   1.4 and a PEEP_l_o_w of 3.1   ±   1.4 cmH_2O. At PEEP_h_i_g_h, we found no significant trend in GI index with low V_T when compared to high V_T (0.49   ±   0.15 versus 0.44   ±   0.09, p = 0.13). At PEEP_l_o_w, we found a significantly higher GI index with low V_T compared to high V_T (0.66   ±   0.19 versus 0.59   ±   0.17, p = 0.01). When comparing the PEEP levels, we found a significantly lower GI index at PEEP_h_i_g_h both for high and low V_T. We conclude that high V_T may lead to a lower GI index, especially at low PEEP settings. This should be taken into account when using the GI index for individual adjustment of ventilator settings. (paper)

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:26999152

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

    Directory of Open Access Journals (Sweden)

    Bersain A. Reyes

    2016-03-01

    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.

  6. Accuracy of height estimation and tidal volume setting using anthropometric formulas in an ICU Caucasian population.

    Science.gov (United States)

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

    2016-12-01

    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; ∂ 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, with a low bias.

  7. Tracheal tube airleak in clinical practice and impact on tidal volume measurement in ventilated neonates.

    Science.gov (United States)

    Mahmoud, Ramadan A; Proquitté, Hans; Fawzy, Naglaa; Bührer, Christoph; Schmalisch, Gerd

    2011-03-01

    To determine the prevalence, size, and factors affecting tracheal tube (TT) leak in clinical practice and their influence on the displayed tidal volume (Vt) in ventilated newborn infants using uncuffed TTs. Monitoring of Vt is important for implementation of lung-protective ventilation strategies but becomes meaningless in the presence of large TT airleaks. Retrospective clinical study. Neonatal intensive care unit. Patient records of 163 neonates ventilated with Babylog 8000 for ≥ 5 hrs with a median (range) gestation age of 31.1 wks (23.3-41.9 wks) and a median birth weight of 1470 g (410-4475 g) were evaluated. : Ventilatory settings, TT leak, and Vt were recorded every 3 hrs. The lowest, median, and highest TT leaks were noted on the day the first TT leak (>5%) occurred, the day on which TT leak peaked, and the day of extubation. A TT leak of >5% was seen in 122 (75%) infants. Neonates with TT leak, compared with those without TT leak, had a longer duration of mechanical ventilation (p 40% commonly seen on the third day of mechanical ventilation. Regression analysis showed that a TT leak of 40% indicated that the displayed Vt was underestimated by 1.2 mL/kg (about 24% of target Vt). TT leak is highly variable, and TT leak of >40% with clinically relevant Vt errors occurred in nearly half of all ventilated neonates. Preterm infants of low birth weight and with small-diameter TTs ventilated for a long period were at greater risk of TT leak.

  8. Orbitofrontal cortex volumes in medication naïve children with major depressive disorder: a magnetic resonance imaging study.

    Science.gov (United States)

    Chen, Hua-Hsuan; Rosenberg, David R; MacMaster, Frank P; Easter, Philip C; Caetano, Sheila C; Nicoletti, Mark; Hatch, John P; Nery, Fabiano G; Soares, Jair C

    2008-12-01

    Adults with major depressive disorder (MDD) are reported to have reduced orbitofrontal cortex (OFC) volumes, which could be related to decreased neuronal density. We conducted a study on medication naïve children with MDD to determine whether abnormalities of OFC are present early in the illness course. Twenty seven medication naïve pediatric Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition (DSM-IV) MDD patients (mean age +/- SD = 14.4 +/- 2.2 years; 10 males) and 26 healthy controls (mean age +/- SD = 14.4 +/- 2.4 years; 12 males) underwent a 1.5T magnetic resonance imaging (MRI) with 3D spoiled gradient recalled acquisition. The OFC volumes were compared using analysis of covariance with age, gender, and total brain volume as covariates. There was no significant difference in either total OFC volume or total gray matter OFC volume between MDD patients and healthy controls. Exploratory analysis revealed that patients had unexpectedly larger total right lateral (F = 4.2, df = 1, 48, p = 0.05) and right lateral gray matter (F = 4.6, df = 1, 48, p = 0.04) OFC volumes compared to healthy controls, but this finding was not significant following statistical correction for multiple comparisons. No other OFC subregions showed a significant difference. The lack of OFC volume abnormalities in pediatric MDD patients suggests the abnormalities previously reported for adults may develop later in life as a result of neural cell loss.

  9. Effect of tidal volume on extravascular lung water content during one-lung ventilation for video-assisted thoracoscopic surgery: a randomised, controlled trial.

    Science.gov (United States)

    Qutub, Hatem; El-Tahan, Mohamed R; Mowafi, Hany A; El Ghoneimy, Yasser F; Regal, Mohamed A; Al Saflan, AbdulHadi A

    2014-09-01

    The use of low tidal volume during one-lung ventilation (OLV) has been shown to attenuate the incidence of acute lung injury after thoracic surgery. To test the effect of tidal volume during OLV for video-assisted thoracoscopic surgery on the extravascular lung water content index (EVLWI). A randomised, double-blind, controlled study. Single university hospital. Thirty-nine patients scheduled for elective video-assisted thoracoscopic surgery. Patients were randomly assigned to one of three groups (n = 13 per group) to ventilate the dependent lung with a tidal volume of 4, 6 or 8 ml  kg(-1) predicted body weight with I:E ratio of 1:2.5 and PEEP of 5 cm H2O. The primary outcomes were perioperative changes in EVLWI and EVLWI to intrathoracic blood volume index (ITBVI) ratio. Secondary outcomes included haemodynamics, oxygenation indices, incidences of postoperative acute lung injury, atelectasis, pneumonia, morbidity and 30-day mortality. A tidal volume of 4 compared with 6 and 8 ml  kg(-1) after 45 min of OLV resulted in an EVLWI of 4.1 [95% confidence interval (CI) 3.5 to 4.7] compared with 7.7 (95% CI 6.7 to 8.6) and 8.6 (95% CI 7.5 to 9.7) ml  kg(-1), respectively (P tidal volume of 4 ml kg during OLV was associated with less lung water content than with larger tidal volumes of 6 to 8 ml kg(-1), although no patient developed acute lung injury. Further studies are required to address the usefulness of EVLWI as a marker for the development of postoperative acute lung injury after the use of a low tidal volume during OLV in patients undergoing pulmonary resection. Clinicaltrials.gov identifier: NCT01762709.

  10. Effects of tidal volume and methacholine on low-frequency total respiratory impedance in dogs.

    Science.gov (United States)

    Lutchen, K R; Jackson, A C

    1990-05-01

    The frequency dependence of respiratory impedance (Zrs) from 0.125 to 4 Hz (Hantos et al., J. Appl. Physiol. 60: 123-132, 1986) may reflect inhomogeneous parallel time constants or the inherent viscoelastic properties of the respiratory tissues. However, studies on the lung alone or chest wall alone indicate that their impedance features are also dependent on the tidal volumes (VT) of the forced oscillations. The goals of this study were 1) to identify how total Zrs at lower frequencies measured with random noise (RN) compared with that measure with larger VT, 2) to identify how Zrs measured with RN is affected by bronchoconstriction, and 3) to identify the impact of using linear models for analyzing such data. We measured Zrs in six healthy dogs by use of a RN technique from 0.125 to 4 Hz or with a ventilator from 0.125 to 0.75 Hz with VT from 50 to 250 ml. Then methacholine was administered and the RN was repeated. Two linear models were fit to each separate set of data. Both models assume uniform airways leading to viscoelastic tissues. For healthy dogs, the respiratory resistance (Rrs) decreased with frequency, with most of the decrease occurring from 0.125 to 0.375 Hz. Significant VT dependence of Rrs was seen only at these lower frequencies, with Rrs higher as VT decreased. The respiratory compliance (Crs) was dependent on VT in a similar fashion at all frequencies, with Crs decreasing as VT decreased. Both linear models fit the data well at all VT, but the viscoelastic parameters of each model were very sensitive to VT. After methacholine, the minimum Rrs increased as did the total drop with frequency. Nevertheless the same models fit the data well, and both the airways and tissue parameters were altered after methacholine. We conclude that inferences based only on low-frequency Zrs data are problematic because of the effects of VT on such data (and subsequent linear modeling of it) and the apparent inability of such data to differentiate parallel

  11. Lower tidal volume strategy (?3?ml/kg) combined with extracorporeal CO2 removal versus ?conventional? protective ventilation (6?ml/kg) in severe ARDS

    OpenAIRE

    Bein, Thomas; Weber-Carstens, Steffen; Goldmann, Anton; M?ller, Thomas; Staudinger, Thomas; Brederlau, J?rg; Muellenbach, Ralf; Dembinski, Rolf; Graf, Bernhard M.; Wewalka, Marlene; Philipp, Alois; Wernecke, Klaus-Dieter; Lubnow, Matthias; Slutsky, Arthur S.

    2013-01-01

    Background Acute respiratory distress syndrome is characterized by damage to the lung caused by various insults, including ventilation itself, and tidal hyperinflation can lead to ventilator induced lung injury (VILI). We investigated the effects of a low tidal volume (V T) strategy (V T???3?ml/kg/predicted body weight [PBW]) using pumpless extracorporeal lung assist in established ARDS. Methods Seventy-nine patients were enrolled after a ?stabilization period? (24?h with optimized therapy an...

  12. Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation.

    Science.gov (United States)

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-07-01

    [Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects were positioned in a 30° lateral recumbent position, and a 2-kgf compression was applied. For expiratory rib cage compression, the rib cage was compressed unilaterally; for expiratory abdominal compression, the area directly above the navel was compressed. Tidal volume values were the actual measured values divided by body weight. [Results] Tidal volume values were as follows: at rest, 7.2 ± 1.7 mL/kg; during expiratory rib cage compression, 8.3 ± 2.1 mL/kg; during expiratory abdominal compression, 9.1 ± 2.2 mL/kg. There was a significant difference between the tidal volume during expiratory abdominal compression and that at rest. The tidal volume in expiratory rib cage compression was strongly correlated with that in expiratory abdominal compression. [Conclusion] These results indicate that expiratory abdominal compression may be an effective alternative to the manual breathing assist procedure.

  13. Cyclic PaO2 oscillations assessed in the renal microcirculation: correlation with tidal volume in a porcine model of lung lavage.

    Science.gov (United States)

    Thomas, Rainer; Möllmann, Christian; Ziebart, Alexander; Liu, Tanghua; David, Matthias; Hartmann, Erik K

    2017-07-11

    Oscillations of the arterial partial pressure of oxygen induced by varying shunt fractions occur during cyclic alveolar recruitment within the injured lung. Recently, these were proposed as a pathomechanism that may be relevant for remote organ injury following acute respiratory distress syndrome. This study examines the transmission of oxygen oscillations to the renal tissue and their tidal volume dependency. Lung injury was induced by repetitive bronchoalveolar lavage in eight anaesthetized pigs. Cyclic alveolar recruitment was provoked by high tidal volume ventilation. Oscillations of the arterial partial pressure of oxygen were measured in real-time in the macrocirculation by multi-frequency phase fluorimetry and in the renal microcirculation by combined white-light spectrometry and laser-Doppler flowmetry during tidal volume down-titration. Significant respiratory-dependent oxygen oscillations were detected in the macrocirculation and transmitted to the renal microcirculation in a substantial extent. The amplitudes of these oscillations significantly correlate to the applied tidal volume and are minimized during down-titration. In a porcine model oscillations of the arterial partial pressure of oxygen are induced by cyclic alveolar recruitment and transmitted to the renal microcirculation in a tidal volume-dependent fashion. They might play a role in organ crosstalk and remote organ damage following lung injury.

  14. Novel approach to the exploitation of the tidal energy. Volume 1: Summary and discussion

    Science.gov (United States)

    Gorlov, A. M.

    1981-12-01

    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.

  15. Lung-Protective Ventilation With Low Tidal Volumes and the Occurrence of Pulmonary Complications in Patients Without Acute Respiratory Distress Syndrome: A Systematic Review and Individual Patient Data Analysis.

    Science.gov (United States)

    Neto, Ary Serpa; Simonis, Fabienne D; Barbas, Carmen S V; Biehl, Michelle; Determann, Rogier M; Elmer, Jonathan; Friedman, Gilberto; Gajic, Ognjen; Goldstein, Joshua N; Linko, Rita; Pinheiro de Oliveira, Roselaine; Sundar, Sugantha; Talmor, Daniel; Wolthuis, Esther K; Gama de Abreu, Marcelo; Pelosi, Paolo; Schultz, Marcus J

    2015-10-01

    Protective mechanical ventilation with low tidal volumes is standard of care for patients with acute respiratory distress syndrome. The aim of this individual patient data analysis was to determine the association between tidal volume and the occurrence of pulmonary complications in ICU patients without acute respiratory distress syndrome and the association between occurrence of pulmonary complications and outcome in these patients. Individual patient data analysis. ICU patients not fulfilling the consensus criteria for acute respiratory distress syndrome at the onset of ventilation. Mechanical ventilation with low tidal volume. The primary endpoint was development of a composite of acute respiratory distress syndrome and pneumonia during hospital stay. Based on the tertiles of tidal volume size in the first 2 days of ventilation, patients were assigned to a "low tidal volume group" (tidal volumes ≤ 7 mL/kg predicted body weight), an "intermediate tidal volume group" (> 7 and volume group" (≥ 10 mL/kg predicted body weight). Seven investigations (2,184 patients) were included. Acute respiratory distress syndrome or pneumonia occurred in 23% of patients in the low tidal volume group, in 28% of patients in the intermediate tidal volume group, and in 31% of the patients in the high tidal volume group (adjusted odds ratio [low vs high tidal volume group], 0.72; 95% CI, 0.52-0.98; p = 0.042). Occurrence of pulmonary complications was associated with a lower number of ICU-free and hospital-free days and alive at day 28 (10.0 ± 10.9 vs 13.8 ± 11.6 d; p volumes is associated with a lower risk of development of pulmonary complications in patients without acute respiratory distress syndrome.

  16. Effect of lung-protective ventilation with lower tidal volumes on clinical outcomes among patients undergoing surgery: a meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Gu, Wan-Jie; Wang, Fei; Liu, Jing-Chen

    2015-02-17

    In anesthetized patients undergoing surgery, the role of lung-protective ventilation with lower tidal volumes is unclear. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of this ventilation strategy on postoperative outcomes. We searched electronic databases from inception through September 2014. We included RCTs that compared protective ventilation with lower tidal volumes and conventional ventilation with higher tidal volumes in anesthetized adults undergoing surgery. We pooled outcomes using a random-effects model. The primary outcome measures were lung injury and pulmonary infection. We included 19 trials (n=1348). Compared with patients in the control group, those who received lung-protective ventilation had a decreased risk of lung injury (risk ratio [RR] 0.36, 95% confidence interval [CI] 0.17 to 0.78; I2=0%) and pulmonary infection (RR 0.46, 95% CI 0.26 to 0.83; I2=8%), and higher levels of arterial partial pressure of carbon dioxide (standardized mean difference 0.47, 95% CI 0.18 to 0.75; I2=65%). No significant differences were observed between the patient groups in atelectasis, mortality, length of hospital stay, length of stay in the intensive care unit or the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen. Anesthetized patients who received ventilation with lower tidal volumes during surgery had a lower risk of lung injury and pulmonary infection than those given conventional ventilation with higher tidal volumes. Implementation of a lung-protective ventilation strategy with lower tidal volumes may lower the incidence of these outcomes. © 2015 Canadian Medical Association or its licensors.

  17. 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.

    Science.gov (United States)

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

    2017-01-01

    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.

  18. 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.

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

    Science.gov (United States)

    Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

    2011-03-10

    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). 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. 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%. 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.

  20. 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

  1. Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution.

    Science.gov (United States)

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

    2011-05-01

    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.

  2. Effects of a preemptive alveolar recruitment strategy on arterial oxygenation during one-lung ventilation with different tidal volumes in patients with normal pulmonary function test.

    Science.gov (United States)

    Jung, Jong Dal; Kim, Sang Hun; Yu, Byung Sik; Kim, Hye Ji

    2014-08-01

    Hypoxemia during one-lung ventilation (OLV) remains a major concern. The present study compared the effect of alveolar recruitment strategy (ARS) on arterial oxygenation during OLV at varying tidal volumes (Vt) with or without positive end-expiratory pressure (PEEP). In total, 120 patients undergoing wedge resection by video assisted thoracostomy were randomized into four groups comprising 30 patients each: those administered a 10 ml/kg tidal volume with or without preemptive ARS (Group H and Group H-ARS, respectively) and those administered a 6 ml/kg tidal volume and a 8 cmH2O PEEP with or without preemptive ARS (Group L and Group L-ARS, respectively). ARS was performed using pressure-controlled ventilation with a 40 cmH2O plateau airway pressure and a 15 cmH2O PEEP for at least 10 breaths until OLV began. Preemptive ARS significantly improved the PaO2/FiO2 ratio compared to the groups that did not receive ARS (P volume combined with 8 cmH2O PEEP after preemptive ARS may reduce the risk of pulmonary injury caused by high tidal volume during one-lung ventilation in patients with normal pulmonary function.

  3. Lung-Protective Ventilation With Low Tidal Volumes and the Occurrence of Pulmonary Complications in Patients Without Acute Respiratory Distress Syndrome: A Systematic Review and Individual Patient Data Analysis

    NARCIS (Netherlands)

    Neto, Ary Serpa; Simonis, Fabienne D.; Barbas, Carmen S. V.; Biehl, Michelle; Determann, Rogier M.; Elmer, Jonathan; Friedman, Gilberto; Gajic, Ognjen; Goldstein, Joshua N.; Linko, Rita; Pinheiro de Oliveira, Roselaine; Sundar, Sugantha; Talmor, Daniel; Wolthuis, Esther K.; Gama de Abreu, Marcelo; Pelosi, Paolo; Schultz, Marcus J.

    2015-01-01

    Protective mechanical ventilation with low tidal volumes is standard of care for patients with acute respiratory distress syndrome. The aim of this individual patient data analysis was to determine the association between tidal volume and the occurrence of pulmonary complications in ICU patients

  4. Increased expression of AQP 1 and AQP 5 in rat lungs ventilated with low tidal volume is time dependent.

    Directory of Open Access Journals (Sweden)

    Gustavo Fabregat

    Full Text Available BACKGROUND AND GOALS: Mechanical ventilation (MV can induce or worsen pulmonary oedema. Aquaporins (AQPs facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats. METHODS: 25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12 and 4 hours (n = 13. Degree of oedema was compared with a group of non-ventilated rats (n = 5. The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (previously amplified by RT-PCR and immunohistochemical staining of AQPs 1 and 5 in lung samples from all groups. RESULTS: Lung oedema and alveolar-capillary membrane permeability did not change during MV. AQP-5 steady state levels in the western blot were increased (p<0.01 at 2 h and 4 h of MV. But in AQP-1 expression these differences were not found. However, the amount of mRNA for AQP-1 was increased at 2 h and 4 h of MV; and for AQP 5 at 4 h of MV. These findings were corroborated by representative immunohistochemical lung samples. CONCLUSION: In lungs from rats ventilated with a low tidal volume the expression of AQP 5 increases gradually with MV duration, but does not cause pulmonary oedema or changes in lung permeability. AQPs may have a protective effect against the oedema induced by MV.

  5. 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.

    2008-01-01

    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

  6. Ventilation with lower tidal volumes for critically ill patients without the acute respiratory distress syndrome: a systematic translational review and meta-analysis

    NARCIS (Netherlands)

    Serpa Neto, Ary; Nagtzaam, Liselotte; Schultz, Marcus J.

    2014-01-01

    There is convincing evidence for benefit from lung-protective mechanical ventilation with lower tidal volumes in patients with the acute respiratory distress syndrome (ARDS). It is uncertain whether this strategy benefits critically ill patients without ARDS as well. This manuscript systematically

  7. 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.

    2017-01-01

    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

  8. Extracorporeal membrane oxygenation (ECMO) as a treatment strategy for severe acute respiratory distress syndrome (ARDS) in the low tidal volume era: A systematic review.

    Science.gov (United States)

    Tillmann, Bourke W; Klingel, Michelle L; Iansavichene, Alla E; Ball, Ian M; Nagpal, A Dave

    2017-10-01

    To evaluate the hospital survival in patients with severe ARDS managed with ECMO and low tidal volume ventilation as compared to patients managed with low tidal volume ventilation alone. Electronic databases were searched for studies of at least 10 adult patients with severe ARDS comparing the use of ECMO with low tidal volume ventilation to mechanical ventilation with a low tidal volume alone. Only studies reporting hospital or ICU survival were included. All identified studies were assessed independently by two reviewers. Of 1782 citations, 27 studies (n=1674) met inclusion criteria. Hospital survival for ECMO patients ranged from 33.3 to 86%, while survival with conventional therapy ranged from 36.3 to 71.2%. Five studies were identified with appropriate control groups allowing comparison, but due to the high degree of variability between studies (I 2 =63%), their results could not be pooled. Two of these studies demonstrated a significant difference, both favouring ECMO over conventional therapy. Given the lack of studies with appropriate control groups, our confidence in a difference in outcome between the two therapies remains weak. Future studies on the use of ECMO for severe ARDS are needed to clarify the role of ECMO in this disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Adaptive Support Ventilation May Deliver Unwanted Respiratory Rate-Tidal Volume Combinations in Patients with Acute Lung Injury Ventilated According to an Open Lung Concept

    NARCIS (Netherlands)

    Dongelmans, Dave A.; Paulus, Frederique; Veelo, Denise P.; Binnekade, Jan M.; Vroom, Margreeth B.; Schultz, Marcus J.

    2011-01-01

    Background: With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury.

  10. Intravenous superoxide dismutase as a protective agent to prevent impairment of lung function induced by high tidal volume ventilation.

    Science.gov (United States)

    Wu, Nan-Chun; Liao, Fan-Ting; Cheng, Hao-Min; Sung, Shih-Hsien; Yang, Yu-Chun; Wang, Jiun-Jr

    2017-07-26

    Positive-pressure mechanical ventilation is essential in assisting patients with respiratory failure in the intensive care unit and facilitating oxygenation in the operating room. However, it was also recognized as a primary factor leading to hospital-acquired pulmonary dysfunction, in which pulmonary oxidative stress and lung inflammation had been known to play important roles. Cu/Zn superoxide dismutase (SOD) is an important antioxidant, and possesses anti-inflammatory capacity. In this study, we aimed to study the efficacy of Cu/Zn SOD, administered intravenously during high tidal volume (HTV) ventilation, to prevent impairment of lung function. Thirty-eight male Sprague-Dawley rats were divided into 3 groups: 5 h ventilation with (A) low tidal volume (LTV; 8 mL/kg; n = 10), (B) high tidal volume (HTV; 18 mL/kg; n = 14), or (C) HTV and intravenous treatment of Cu/Zn SOD at a dose of 1000 U/kg/h (HTV + SOD; n = 14). Lung function was evaluated both at baseline and after 5-h ventilation. Lung injury was assessed by histological examination, lung water and protein contents in the bronchoalveolar lavage fluid (BALF). Pulmonary oxidative stress was examined by concentrations of methylguanidine (MG) and malondialdehyde (MDA) in BALF, and antioxidative activity by protein expression of glutathione peroxidase-1 (GPx-1) in the lung. Severity of lung inflammation was evaluated by white blood cell and differential count in BALF, and protein expression of inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and mRNA expression of nuclear factor-κB (NF-κB) in the lung. We also examined protein expression of surfactant protein (SP)-A and D and we measured hourly changes in serum nitric oxide (NO) level. Five hours of LTV ventilation did not induce a major change in lung function, whereas 5 h of HTV ventilation induced apparent combined restrictive and

  11. Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.

    Science.gov (United States)

    Cordioli, Ricardo Luiz; Park, Marcelo; Costa, Eduardo Leite Vieira; Gomes, Susimeire; Brochard, Laurent; Amato, Marcelo Britto Passos; Azevedo, Luciano Cesar Pontes

    2014-12-01

    The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, V T was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, V T was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, V T could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, V T progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.

  12. Comparison of changes in tidal volume associated with expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation

    OpenAIRE

    Morino, Akira; Shida, Masahiro; Tanaka, Masashi; Sato, Kimihiro; Seko, Toshiaki; Ito, Shunsuke; Ogawa, Shunichi; Takahashi, Naoaki

    2015-01-01

    [Purpose] This study was designed to compare and clarify the relationship between expiratory rib cage compression and expiratory abdominal compression in patients on prolonged mechanical ventilation, with a focus on tidal volume. [Subjects and Methods] The subjects were 18 patients on prolonged mechanical ventilation, who had undergone tracheostomy. Each patient received expiratory rib cage compression and expiratory abdominal compression; the order of implementation was randomized. Subjects ...

  13. Interaction between peri-operative blood transfusion, tidal volume, airway pressure and postoperative ARDS: an individual patient data meta-analysis.

    Science.gov (United States)

    Serpa Neto, Ary; Juffermans, Nicole P; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Biehl, Michelle; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; Jaber, Samir; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Memtsoudis, Stavros G; Miranda, Dinis Reis; Moine, Pierre; Paparella, Domenico; Ranieri, Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

    2018-01-01

    Transfusion of blood products and mechanical ventilation with injurious settings are considered risk factors for postoperative lung injury in surgical Patients. A systematic review and individual patient data meta-analysis was done to determine the independent effects of peri-operative transfusion of blood products, intra-operative tidal volume and airway pressure in adult patients undergoing mechanical ventilation for general surgery, as well as their interactions on the occurrence of postoperative acute respiratory distress syndrome (ARDS). Observational studies and randomized trials were identified by a systematic search of MEDLINE, CINAHL, Web of Science, and CENTRAL and screened for inclusion into a meta-analysis. Individual patient data were obtained from the corresponding authors. Patients were stratified according to whether they received transfusion in the peri-operative period [red blood cell concentrates (RBC) and/or fresh frozen plasma (FFP)], tidal volume size [≤7 mL/kg predicted body weight (PBW), 7-10 and >10 mL/kg PBW] and airway pressure level used during surgery (≤15, 15-20 and >20 cmH 2 O). The primary outcome was development of postoperative ARDS. Seventeen investigations were included (3,659 patients). Postoperative ARDS occurred in 40 (7.2%) patients who received at least one blood product compared to 40 patients (2.5%) who did not [adjusted hazard ratio (HR), 2.32; 95% confidence interval (CI), 1.25-4.33; P=0.008]. Incidence of postoperative ARDS was highest in patients ventilated with tidal volumes of >10 mL/kg PBW and having airway pressures of >20 cmH 2 O receiving both RBC and FFP, and lowest in patients ventilated with tidal volume of ≤7 mL/kg PBW and having airway pressures of ≤15 cmH 2 O with no transfusion. There was a significant interaction between transfusion and airway pressure level (P=0.002) on the risk of postoperative ARDS. Peri-operative transfusion of blood products is associated with an increased risk of

  14. Effect of leak and breathing pattern on the accuracy of tidal volume estimation by commercial home ventilators: a bench study.

    Science.gov (United States)

    Luján, Manel; Sogo, Ana; Pomares, Xavier; Monsó, Eduard; Sales, Bernat; Blanch, Lluís

    2013-05-01

    New home ventilators are able to provide clinicians data of interest through built-in software. Monitoring of tidal volume (VT) is a key point in the assessment of the efficacy of home mechanical ventilation. To assess the reliability of the VT provided by 5 ventilators in a bench test. Five commercial ventilators from 4 different manufacturers were tested in pressure support mode with the help of a breathing simulator under different conditions of mechanical respiratory pattern, inflation pressure, and intentional leakage. Values provided by the built-in software of each ventilator were compared breath to breath with the VT monitored through an external pneumotachograph. Ten breaths for each condition were compared for every tested situation. All tested ventilators underestimated VT (ranges of -21.7 mL to -83.5 mL, which corresponded to -3.6% to -14.7% of the externally measured VT). A direct relationship between leak and underestimation was found in 4 ventilators, with higher underestimations of the VT when the leakage increased, ranging between -2.27% and -5.42% for each 10 L/min increase in the leakage. A ventilator that included an algorithm that computes the pressure loss through the tube as a function of the flow exiting the ventilator had the minimal effect of leaks on the estimation of VT (0.3%). In 3 ventilators the underestimation was also influenced by mechanical pattern (lower underestimation with restrictive, and higher with obstructive). The inclusion of algorithms that calculate the pressure loss as a function of the flow exiting the ventilator in commercial models may increase the reliability of VT estimation.

  15. Association between use of lung-protective ventilation with lower tidal volumes and clinical outcomes among patients without acute respiratory distress syndrome: a meta-analysis.

    Science.gov (United States)

    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

    2012-10-24

    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. To determine whether use of lower tidal volumes is associated with improved outcomes of patients receiving ventilation who do not have ARDS. MEDLINE, CINAHL, Web of Science, and Cochrane Central Register of Controlled Trials up to August 2012. Eligible studies evaluated use of lower vs higher tidal volumes in patients without ARDS at onset of mechanical ventilation and reported lung injury development, overall mortality, pulmonary infection, atelectasis, and biochemical alterations. Three reviewers extracted data on study characteristics, methods, and outcomes. Disagreement was resolved by consensus. Twenty articles (2822 participants) were included. Meta-analysis using a fixed-effects model showed a decrease in lung injury development (risk ratio [RR], 0.33; 95% CI, 0.23 to 0.47; I2, 0%; number needed to treat [NNT], 11), and mortality (RR, 0.64; 95% CI, 0.46 to 0.89; I2, 0%; NNT, 23) in patients receiving ventilation with lower tidal volumes. The results of lung injury development were similar when stratified by the type of study (randomized vs nonrandomized) and were significant only in randomized trials for pulmonary infection and only in nonrandomized trials for mortality. Meta-analysis using a random-effects model showed, in protective ventilation groups, a lower incidence of pulmonary infection (RR, 0.45; 95% CI, 0.22 to 0.92; I2, 32%; NNT, 26), lower mean (SD) hospital length of stay (6.91 [2.36] vs 8.87 [2.93] days, respectively; standardized mean difference [SMD], 0.51; 95% CI, 0.20 to 0.82; I2, 75%), higher mean (SD) PaCO2 levels (41.05 [3.79] vs 37.90 [4.19] mm Hg, respectively; SMD, -0.51; 95% CI, -0.70 to -0.32; I2, 54%), and lower mean (SD) pH values (7.37 [0.03] vs 7.40 [0

  16. Tidal power: trends and developments

    International Nuclear Information System (INIS)

    1992-01-01

    This volume covers works and studies on tidal power currently being undertaken, both nationally and internationally. The 20 papers included cover the proposed Mersey barrage, the Severn estuary and several papers on the Severn barrage. The Department of Energy's continued variety of generic work on tidal power and various overseas studies carried out by other experts are also detailed, giving the reader an up to date picture of developments in tidal power worldwide. Separate abstracts have been prepared for the individual papers. (author)

  17. Variable effectiveness of stepwise implementation of nudge-type interventions to improve provider compliance with intraoperative low tidal volume ventilation.

    Science.gov (United States)

    O'Reilly-Shah, Vikas N; Easton, George S; Jabaley, Craig S; Lynde, Grant C

    2018-05-18

    Identifying mechanisms to improve provider compliance with quality metrics is a common goal across medical disciplines. Nudge interventions are minimally invasive strategies that can influence behavioural changes and are increasingly used within healthcare settings. We hypothesised that nudge interventions may improve provider compliance with lung-protective ventilation (LPV) strategies during general anaesthesia. We developed an audit and feedback dashboard that included information on both provider-level and department-level compliance with LPV strategies in two academic hospitals, two non-academic hospitals and two academic surgery centres affiliated with a single healthcare system. Dashboards were emailed to providers four times over the course of the 9-month study. Additionally, the default setting on anaesthesia machines for tidal volume was decreased from 700 mL to 400 mL. Data on surgical cases performed between 1 September 2016 and 31 May 2017 were examined for compliance with LPV. The impact of the interventions was assessed via pairwise logistic regression analysis corrected for multiple comparisons. A total of 14 793 anaesthesia records were analysed. Absolute compliance rates increased from 59.3% to 87.8%preintervention to postintervention. Introduction of attending physician dashboards resulted in a 41% increase in the odds of compliance (OR 1.41, 95% CI 1.17 to 1.69, p=0.002). Subsequently, the addition of advanced practice provider and resident dashboards lead to an additional 93% increase in the odds of compliance (OR 1.93, 95% CI 1.52 to 2.46, p<0.001). Lastly, modifying ventilator defaults led to a 376% increase in the odds of compliance (OR 3.76, 95% CI 3.1 to 4.57, p<0.001). Audit and feedback tools in conjunction with default changes improve provider compliance. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise

  18. Intraoperative protective mechanical ventilation for prevention of postoperative pulmonary complications: a comprehensive review of the role of tidal volume, positive end-expiratory pressure, and lung recruitment maneuvers.

    Science.gov (United States)

    Güldner, Andreas; Kiss, Thomas; Serpa Neto, Ary; Hemmes, Sabrine N T; Canet, Jaume; Spieth, Peter M; Rocco, Patricia R M; Schultz, Marcus J; Pelosi, Paolo; Gama de Abreu, Marcelo

    2015-09-01

    Postoperative pulmonary complications are associated with increased morbidity, length of hospital stay, and mortality after major surgery. Intraoperative lung-protective mechanical ventilation has the potential to reduce the incidence of postoperative pulmonary complications. This review discusses the relevant literature on definition and methods to predict the occurrence of postoperative pulmonary complication, the pathophysiology of ventilator-induced lung injury with emphasis on the noninjured lung, and protective ventilation strategies, including the respective roles of tidal volumes, positive end-expiratory pressure, and recruitment maneuvers. The authors propose an algorithm for protective intraoperative mechanical ventilation based on evidence from recent randomized controlled trials.

  19. Impact of Different Tidal Volume Levels at Low Mechanical Power on Ventilator-Induced Lung Injury in Rats

    Directory of Open Access Journals (Sweden)

    Lillian Moraes

    2018-04-01

    Full Text Available Tidal volume (VT has been considered the main determinant of ventilator-induced lung injury (VILI. Recently, experimental studies have suggested that mechanical power transferred from the ventilator to the lungs is the promoter of VILI. We hypothesized that, as long as mechanical power is kept below a safe threshold, high VT should not be injurious. The present study aimed to investigate the impact of different VT levels and respiratory rates (RR on lung function, diffuse alveolar damage (DAD, alveolar ultrastructure, and expression of genes related to inflammation [interleukin (IL-6], alveolar stretch (amphiregulin, epithelial [club cell secretory protein (CC16] and endothelial [intercellular adhesion molecule (ICAM-1] cell injury, and extracellular matrix damage [syndecan-1, decorin, and metalloproteinase (MMP-9] in experimental acute respiratory distress syndrome (ARDS under low-power mechanical ventilation. Twenty-eight Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 21 animals were randomly assigned to ventilation (2 h with low mechanical power at three different VT levels (n = 7/group: (1 VT = 6 mL/kg and RR adjusted to normocapnia; (2 VT = 13 mL/kg; and 3 VT = 22 mL/kg. In the second and third groups, RR was adjusted to yield low mechanical power comparable to that of the first group. Mechanical power was calculated as [(ΔP,L2/Est,L/2]× RR (ΔP,L = transpulmonary driving pressure, Est,L = static lung elastance. Seven rats were not mechanically ventilated (NV and were used for molecular biology analysis. Mechanical power was comparable among groups, while VT gradually increased. ΔP,L and mechanical energy were higher in VT = 22 mL/kg than VT = 6 mL/kg and VT = 13 mL/kg (p < 0.001 for both. Accordingly, DAD score increased in VT = 22 mL/kg compared to VT = 6 mL/kg and VT = 13 mL/kg [23(18.5–24.75 vs. 16(12–17.75 and 16(13.25–18, p < 0.05, respectively]. VT = 22 mL/kg was associated with higher

  20. Tidal power

    International Nuclear Information System (INIS)

    Baker, A.C.

    1991-01-01

    This book describes how large tides develop in particular places and how the energy could be extracted by building suitable barrages. The principal features of a barrage and possible methods of operation are described in detail. Although a tidal power barrage would be non-polluting, the resulting changes in the tidal regime would have important environmental effects. These are discussed together with the economics of tidal power. Methods of assessing the likely cost of electricity from any site are set out and applied to possible sites around the world. (author)

  1. Tidal radiation

    International Nuclear Information System (INIS)

    Mashhoon, B.

    1977-01-01

    The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions

  2. Tidal energy

    International Nuclear Information System (INIS)

    Lochte, H.G.

    1995-01-01

    Together with wave energy, ocean thermal energy, and the often overlooked energy from ocean curents tidal energy belongs to those renewable energy sources that can be subsumed under the generic term of ocean energy. All that these energy sources have in common, however, is that they are found in the ocean. The present article discusses tidal energy with respect to the four principal factors determining the scope of a renewable energy source, namely global, technical, and economic availability and ecological acceptability. (orig.) [de

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

    Science.gov (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

    2017-12-02

    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

  4. Intraoperative and postoperative evaluation of low tidal volume combined with low-level positive end-expiratory pressure ventilation in laparoscopic surgery in elderly patients

    Directory of Open Access Journals (Sweden)

    Ye-Qiu Li

    2016-01-01

    Full Text Available Objective: To evaluate intraoperative and postoperative condition of low tidal volume combined with low-level positive end-expiratory pressure ventilation in laparoscopic surgery in elderly patients. Methods: A total of 176 cases of elderly patients (more than 60 years old receiving laparoscopic surgery in our hospital from July 2013 to July 2015 were selected as research subjects and randomly divided into observation group and control group, each group included 88 cases, control group received conventional ventilation strategy, observation group received low tidal volume combined with low-level positive end-expiratory pressure ventilation strategy, and then levels of hemodynamic indexes, respiratory mechanical indexes, serology indexes and cerebral vessel related indexes, etc of two groups were compared. Results: Intraoperative and postoperative heart rate and mean arterial pressure levels of observation group were lower than those of control group, arterial partial pressure of oxygen and oxygenation index levels were higher than those of control group and differences had statistical significance (P<0.05; intraoperative APIP and Pplat values of observation group were lower than those of control group, Cs value was higher than that of control group and differences had statistical significance (P<0.05; intraoperative and postoperative serum IL-8 and TNF-α levels of observation group were lower than those of control group, IL-10 level was higher than that of control group and differences had statistical significance (P<0.05; intraoperative and postoperative PjvO2, SjvO2 and CjvO2 levels of observation group were higher than those of control group, Da-jvO2 level was lower than that of control group and differences had statistical significance (P<0.05. Conclusions: When elderly patients receive laparoscopic surgery, the use of low tidal volume combined with low-level positive end-expiratory pressure ventilation strategy can stabilize hemodynamic

  5. 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

    2012-03-01

    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.

  6. Combining "open-lung" ventilation and arteriovenous extracorporeal lung assist: influence of different tidal volumes on gas exchange in experimental lung failure.

    Science.gov (United States)

    Muellenbach, Ralf M; Kredel, Markus; Kuestermann, Julian; Klingelhoefer, Michael; Schuster, Frank; Wunder, Christian; Kranke, Peter; Roewer, Norbert; Brederlau, Jörg

    2009-08-01

    Although low-tidal ventilation may reduce mortality in acute respiratory distress syndrome (ARDS), it can also result in severe respiratory acidosis and lung derecruitment. This study tested the hypothesis that combining "open-lung" ventilation and arteriovenous extracorporeal lung assist (av-ECLA) allows for maximal tidal volume (VT) reduction without the development of decompensated respiratory acidosis and impairment of oxygenation. After induction of ARDS in eight female pigs (56.1+/-3.2 kg), lung recruitment was performed and positive end-expiratory pressure was set 3 cmH2O above the lower inflection point of the pressure-volume curve. All animals were ventilated in the pressure-controlled ventilation mode (PCV) with VTs ranging from 0-8 ml/kg. At each VT, gas exchange and hemodynamic measurements were obtained with the av-ECLA circuit clamped and declamped. With each declamping, the gas flow through the membrane lung was set to 10 l of oxygen/min. The respiratory rate was adjusted to maintain normocapnia, but limited to 40/min. After lung recruitment, oxygenation remained significantly improved although VTs were minimized to 0 ml/kg (p<0.05). PaO2 was significantly improved during PCV and av-ECLA compared with PCV alone at VTs <4 ml/kg (p<0.05). With VT <6 ml/kg, severe acidosis could only be avoided if PCV was combined with av-ECLA. Due to sufficient CO2 elimination during av-ECLA, the VTs could be reduced to 0-2 ml/kg without the risk of decompensated respiratory acidosis. It was also shown that the "open-lung" strategy chosen was associated with sustained improvements in oxygenation, even though VTs were minimized.

  7. Tides and tidal currents

    NARCIS (Netherlands)

    Roos, A.

    1997-01-01

    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.

  8. Adjusting tidal volume to stress index in an open lung condition optimizes ventilation and prevents overdistension in an experimental model of lung injury and reduced chest wall compliance.

    Science.gov (United States)

    Ferrando, Carlos; Suárez-Sipmann, Fernando; Gutierrez, Andrea; Tusman, Gerardo; Carbonell, Jose; García, Marisa; Piqueras, Laura; Compañ, Desamparados; Flores, Susanie; Soro, Marina; Llombart, Alicia; Belda, Francisco Javier

    2015-01-13

    The stress index (SI), a parameter derived from the shape of the pressure-time curve, can identify injurious mechanical ventilation. We tested the hypothesis that adjusting tidal volume (VT) to a non-injurious SI in an open lung condition avoids hypoventilation while preventing overdistension in an experimental model of combined lung injury and low chest-wall compliance (Ccw). Lung injury was induced by repeated lung lavages using warm saline solution, and Ccw was reduced by controlled intra-abdominal air-insufflation in 22 anesthetized, paralyzed and mechanically ventilated pigs. After injury animals were recruited and submitted to a positive end-expiratory pressure (PEEP) titration trial to find the PEEP level resulting in maximum compliance. During a subsequent four hours of mechanical ventilation, VT was adjusted to keep a plateau pressure (Pplat) of 30 cmH2O (Pplat-group, n = 11) or to a SI between 0.95 and 1.05 (SI-group, n = 11). Respiratory rate was adjusted to maintain a 'normal' PaCO2 (35 to 65 mmHg). SI, lung mechanics, arterial-blood gases haemodynamics pro-inflammatory cytokines and histopathology were analyzed. In addition Computed Tomography (CT) data were acquired at end expiration and end inspiration in six animals. PaCO2 was significantly higher in the Pplat-group (82 versus 53 mmHg, P = 0.01), with a resulting lower pH (7.19 versus 7.34, P = 0.01). We observed significant differences in VT (7.3 versus 5.4 mlKg(-1), P = 0.002) and Pplat values (30 versus 35 cmH2O, P = 0.001) between the Pplat-group and SI-group respectively. SI (1.03 versus 0.99, P = 0.42) and end-inspiratory transpulmonary pressure (PTP) (17 versus 18 cmH2O, P = 0.42) were similar in the Pplat- and SI-groups respectively, without differences in overinflated lung areas at end- inspiration in both groups. Cytokines and histopathology showed no differences. Setting tidal volume to a non-injurious stress index in an open lung condition improves

  9. An evaluation of peak inspiratory pressure, tidal volume, and ventilatory frequency during ventilation with a neonatal self-inflating bag resuscitator.

    Science.gov (United States)

    Bassani, Mariana Almada; Filho, Francisco Mezzacappa; de Carvalho Coppo, Maria Regina; Martins Marba, Sérgio Tadeu

    2012-04-01

    Although the self-inflating bag is widely used in the hospital setting, variability of delivered ventilatory parameters is usually high, which might result in both hypoventilation and lung injury. The aims of this study were to assess possible sources of the high variability and to evaluate the adequacy of obtained values in relation to the recommended values for neonatal resuscitation. This was an experimental study in which 172 health professionals (physicians, resident physicians, physiotherapists, nurses, and nursing technicians) who work with neonatal intensive care manually ventilated a test lung (adjusted to simulate the lungs of an intubated term newborn) with a self-inflating bag in 5 different handling techniques, using 10, 5, 4, 3, and 2 fingers. Delivered values of peak inspiratory pressure (PIP), tidal volume (V(T)), and ventilatory frequency (f) were compared, taking into account the different handling modalities and professions by analysis of variance for repeated measures. Chi-square, the Friedman test and the Fisher exact tests were performed to compare the delivered and standard values. PIP and V(T) were significantly affected by the handling technique, with higher values for a greater number of fingers used for ventilation. Profession also influenced V(T) and f significantly: physiotherapists tended to deliver higher volumes and lower rates. Nevertheless, we observed high variability of all studied ventilatory parameters and overall inadequacy of obtained values. Most volunteers delivered excessive pressures and volumes at insufficient ventilatory frequency. Delivered values seem to depend on operators' individual and professional differences, as well as on the number of fingers used to compress the bag. However, from the clinical point of view, it is important to point out the high occurrence of inadequate delivered values, regardless of handling technique and profession.

  10. 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

    Directory of Open Access Journals (Sweden)

    L Mousavi Seresht

    2014-01-01

    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.

  11. A bench evaluation of fraction of oxygen in air delivery and tidal volume accuracy in home care ventilators available for hospital use

    Science.gov (United States)

    Baboi, Loredana; Subtil, Fabien

    2016-01-01

    Background Turbine-powered ventilators are not only designed for long-term ventilation at home but also for hospital use. It is important to verify their capabilities in delivering fraction of oxygen in air (FIO2) and tidal volume (VT). Methods We assessed the FIO2 accuracy and the VT delivery in four home care ventilators (HCV) on the bench. The four HCV were Astral 150, Elisée 150, Monnal T50 and Trilogy 200 HCV, which were connected to a lung model (ASL 5000). For assessing FIO2 accuracy, lung model was set to mimic an obstructive lung and HCV were set in volume controlled mode (VC). They supplied with air, 3 or 15 L/min oxygen and FIO2 was measured by using a ventilator tester (Citrex H4TM). For the VT accuracy, the lung model was set in a way to mimic three adult configurations (normal, obstructive, or restrictive respiratory disorder) and one pediatric configuration. Each HCV was set in VC. Two VT (300 and 500 mL) in adult lung configuration and one 50 mL VT in pediatric lung configuration, at two positive end expiratory pressures 5 and 10 cmH2O, were tested. VT accuracy was measured as volume error (the relative difference between set and measured VT). Statistical analysis was performed by suing one-factor ANOVA with a Bonferroni correction for multiple tests. Results For Astral 150, Elisée 150, Monnal T50 and Trilogy 200, FIO2 averaged 99.2%, 93.7%, 86.3%, and 62.1%, respectively, at 15 L/min oxygen supplementation rate (P<0.001). Volume error was 0.5%±0%, −38%±0%, −9%±0%, −29%±0% and −36%±0% for pediatric lung condition (P<0.001). In adult lung configurations, Monnal T50 systematically over delivered VT and Trilogy 150 was sensitive to lung configuration when VT was set to 300 mL at either positive end-expiratory pressure (PEEP). Conclusions HCV are different in terms of FIO2 efficiency and VT delivery. PMID:28149559

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

    Science.gov (United States)

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

    2016-05-26

    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. Effects of Dexmedetomidine Infusion on Inflammatory Responses and Injury of Lung Tidal Volume Changes during One-Lung Ventilation in Thoracoscopic Surgery: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Chun-Yu Wu

    2018-01-01

    Full Text Available One-lung ventilation in thoracic surgery provokes profound systemic inflammatory responses and injury related to lung tidal volume changes. We hypothesized that the highly selective a2-adrenergic agonist dexmedetomidine attenuates these injurious responses. Sixty patients were randomly assigned to receive dexmedetomidine or saline during thoracoscopic surgery. There is a trend of less postoperative medical complication including that no patients in the dexmedetomidine group developed postoperative medical complications, whereas four patients in the saline group did (0% versus 13.3%, p=0.1124. Plasma inflammatory and injurious biomarkers between the baseline and after resumption of two-lung ventilation were particularly notable. The plasma high-mobility group box 1 level decreased significantly from 51.7 (58.1 to 33.9 (45.0 ng.ml−1 (p<0.05 in the dexmedetomidine group, which was not observed in the saline group. Plasma monocyte chemoattractant protein 1 [151.8 (115.1 to 235.2 (186.9 pg.ml−1, p<0.05] and neutrophil elastase [350.8 (154.5 to 421.9 (106.1 ng.ml−1, p<0.05] increased significantly only in the saline group. In addition, plasma interleukin-6 was higher in the saline group than in the dexmedetomidine group at postoperative day 1 [118.8 (68.8 versus 78.5 (58.8 pg.ml−1, p=0.0271]. We conclude that dexmedetomidine attenuates one-lung ventilation-associated inflammatory and injurious responses by inhibiting alveolar neutrophil recruitment in thoracoscopic surgery.

  14. Low tidal volume and high positive end-expiratory pressure mechanical ventilation results in increased inflammation and ventilator-associated lung injury in normal lungs.

    Science.gov (United States)

    Hong, Caron M; Xu, Da-Zhong; Lu, Qi; Cheng, Yunhui; Pisarenko, Vadim; Doucet, Danielle; Brown, Margaret; Aisner, Seena; Zhang, Chunxiang; Deitch, Edwin A; Delphin, Ellise

    2010-06-01

    Protective mechanical ventilation with low tidal volume (Vt) and low plateau pressure reduces mortality and decreases the length of mechanical ventilation in patients with acute respiratory distress syndrome. Mechanical ventilation that will protect normal lungs during major surgical procedures of long duration may improve postoperative outcomes. We performed an animal study comparing 3 ventilation strategies used in the operating room in normal lungs. We compared the effects on pulmonary mechanics, inflammatory mediators, and lung tissue injury. Female pigs were randomized into 3 groups. Group H-Vt/3 (n = 6) was ventilated with a Vt of 15 mL/kg predicted body weight (PBW)/positive end-expiratory pressure (PEEP) of 3 cm H(2)O, group L-Vt/3 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 3 cm H(2)O, and group L-Vt/10 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 10 cm H(2)O, for 8 hours. Hemodynamics, airway mechanics, arterial blood gases, and inflammatory markers were monitored. Bronchoalveolar lavage (BAL) was analyzed for inflammatory markers and protein concentration. The right lower lobe was assayed for mRNA of specific cytokines. The right lower lobe and right upper lobe were evaluated histologically. In contrast to groups H-Vt/3 and L-Vt/3, group L-Vt/10 exhibited a 6-fold increase in inflammatory mediators in BAL (P ventilation with high PEEP resulted in increased production of inflammatory markers. Low PEEP resulted in lower levels of inflammatory markers. High Vt/low PEEP resulted in less histologic lung injury.

  15. Adaptive support ventilation may deliver unwanted respiratory rate-tidal volume combinations in patients with acute lung injury ventilated according to an open lung concept.

    Science.gov (United States)

    Dongelmans, Dave A; Paulus, Frederique; Veelo, Denise P; Binnekade, Jan M; Vroom, Margreeth B; Schultz, Marcus J

    2011-05-01

    With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury. Patients with acute lung injury were ventilated according to a local guideline advising the use of lower V(T) (6-8 ml/kg predicted body weight), high concentrations of positive end-expiratory pressure, and recruitment maneuvers. Ventilation parameters were recorded when the ventilator was switched to adaptive support ventilation, and after recruitment maneuvers. If V(T) increased more than 8 ml/kg predicted body weight, airway pressure was limited to correct for the rise of V(T). Ten patients with a mean (±SD) Pao(2)/Fio(2) of 171 ± 86 mmHg were included. After a switch from pressure-controlled ventilation to adaptive support ventilation, respiratory rate declined (from 31 ± 5 to 21 ± 6 breaths/min; difference = 10 breaths/min, 95% CI 3-17 breaths/min, P = 0.008) and V(T) increased (from 6.5 ± 0.8 to 9.0 ± 1.6 ml/kg predicted body weight; difference = 2.5 ml, 95% CI 0.4-4.6 ml/kg predicted body weight, P = 0.02). Pressure limitation corrected for the rise of V(T), but minute ventilation declined, forcing the user to switch back to pressure-controlled ventilation. Adaptive support ventilation, compared with pressure-controlled ventilation in an open lung strategy setting, delivers a lower respiratory rate-higher V(T) combination. Pressure limitation does correct for the rise of V(T), but leads to a decline in minute ventilation.

  16. Neonatal mannequin comparison of the Upright self-inflating bag and snap-fit mask versus standard resuscitators and masks: leak, applied load and tidal volumes.

    Science.gov (United States)

    Rafferty, Anthony Richard; Johnson, Lucy; Davis, Peter G; Dawson, Jennifer Anne; Thio, Marta; Owen, Louise S

    2017-11-30

    Neonatal mask ventilation is a difficult skill to acquire and maintain. Mask leak is common and can lead to ineffective ventilation. The aim of this study was to determine whether newly available neonatal self-inflating bags and masks could reduce mask leak without additional load being applied to the face. Forty operators delivered 1 min episodes of mask ventilation to a mannequin using the Laerdal Upright Resuscitator, a standard Laerdal infant resuscitator (Laerdal Medical) and a T-Piece Resuscitator (Neopuff), using both the Laerdal snap-fit face mask and the standard Laerdal size 0/1 face mask (equivalent sizes). Participants were asked to use pressure sufficient to achieve 'appropriate' chest rise. Leak, applied load, airway pressure and tidal volume were measured continuously. Participants were unaware that load was being recorded. There was no difference in mask leak between resuscitation devices. Leak was significantly lower when the snap-fit mask was used with all resuscitation devices, compared with the standard mask (14% vs 37% leak, Pmask was preferred by 83% of participants. The device-mask combinations had no significant effect on applied load. The Laerdal Upright Resuscitator resulted in similar leak to the other resuscitation devices studied, and did not exert additional load to the face and head. The snap-fit mask significantly reduced overall leak with all resuscitation devices and was the mask preferred by participants. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. 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

    2008-09-01

    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

  18. Respiratory effects of low versus high tidal volume with or without positive end-expiratory pressure in anesthetized dogs with healthy lungs.

    Science.gov (United States)

    De Monte, Valentina; Bufalari, Antonello; Grasso, Salvatore; Ferrulli, Fabienne; Crovace, Alberto Maria; Lacitignola, Luca; Staffieri, Francesco

    2018-05-01

    OBJECTIVE To evaluate the impact of 2 tidal volumes (T V s) with or without positive end-expiratory pressure (PEEP) on lung mechanics, aeration, and gas exchange in healthy anesthetized dogs. ANIMALS 40 mixed-breed dogs with healthy lungs. PROCEDURES Anesthetized dogs were randomly assigned to 4 groups (n = 10/group) with different ventilatory settings: T V of 8 mL/kg and PEEP of 0 cm H 2 O (low T V group), T V of 8 mL/kg and PEEP of 5 cm H 2 O (low T V plus PEEP group), T V of 15 mL/kg and PEEP of 0 cm H 2 O (high T V group), or T V of 15 mL/kg and PEEP of 5 cm H 2 O (high T V plus PEEP group). Expired CO 2 and respiratory rate were titrated on the basis of a predetermined stepwise protocol. Gas exchange, respiratory mechanics, and pulmonary aeration were evaluated by means of CT 30 minutes after starting mechanical ventilation at the assigned setting. RESULTS Partial pressures of arterial and expired CO 2 were higher in the low T V and low T V plus PEEP groups than in the high T V and high T V plus PEEP groups. Peak and plateau airway pressures were higher in the PEEP group than in the other groups. Static lung compliance was higher in the high T V plus PEEP group than in the low T V group. Relative percentages of atelectatic and poorly aerated lung were lower in the high T V plus PEEP group than in the other groups. Oxygenation was similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE Differences in T V and PEEP application during mechanical ventilation may affect respiratory function in anesthetized dogs with healthy lungs. Ventilation with a T V of 15 mL/kg and PEEP of 5 cm H 2 O significantly improved lung compliance and reduced the amount of atelectatic and poorly aerated lung.

  19. [Study of setting of ventilator volume tidal and airway pressure alarm threshold with continuous extra-sternum heart compression in cardiopulmonary resuscitation].

    Science.gov (United States)

    Luo, Jian-yu; Wang, Xiao-yuan; Cai, Tian-bin; Jiang, Wen-fang

    2013-02-01

    To investigate the setting of ventilator volume tidal (VT) and airway pressure alarm threshold during cardiopulmonary resuscitation (CPR) by continuous extra-sternum heart compression. Forty cases with respiration and cardiac arrest in the department of critical care medicine were randomly divided into low VT ventilation group and conventional VT group. Both groups were given the volume control mode. In the low VT ventilation group, VT was set on 6 - 7 ml/kg, and high pressure alarm threshold was adjusted to 60 cm H2O by the conventional 40 cm H2O during CPR. In the conventional VT group, VT and high pressure alarm threshold were set at 8 - 12 ml/kg and 40 cm H2O, respectively. Real-time actual VT, peak inspiratory pressure (PIP), and arterial blood gas test, blood lactic acid at 10 minutes and 30 minutes after CPR were observed. At 10 minutes after CPR, in the low VT ventilation group, arterial blood pH, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), HCO3(-), arterial oxygen saturation (SaO2) and blood lactic acid were better as compared with those in the conventional VT ventilation group (pH: 7.21±0.09 vs. 7.13±0.07, PaO2: 45.35±5.92 mm Hg vs. 40.70±4.70 mm Hg, PaCO2: 57.10±7.59 mm Hg vs. 61.60±5.47 mm Hg, HCO3(-): 18.50±3.50 mmol/L vs. 14.75±2.65 mmol/L, SaO2: 0.796±0.069 vs. 0.699±0.066, blood lactic acid: 7.07±1.60 mmol/L vs. 8.13±1.56 mmol/L, all P<0.05). The success rate of resuscitation in the low VT ventilation group was higher than that of the conventional VT ventilation group (45% vs. 15%, P<0.05), and PIP (cm H2O) of low VT ventilation group was lower than that of the conventional VT group (37.25±7.99 cm H2O vs. 42.70±7.40 cm H2O, P<0.05). In all the patients in both groups barotrauma did not occur. The strategy of low ventilator VT (6 - 7 ml/kg) with appropriate elevation of airway pressure alarm threshold was better than that of conventional ventilation setting, with no increase in

  20. VE of construction industry

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1987-10-15

    This book gives descriptions of basic of VE of construction industry including doing away with mannerism, necessity of cost reduction, management method of cost reduction, thinking of idea, target of VE, starting VE activity, technical method of VE of construction industry such as thinking of idea with brainstorming, function trade method, new brainstorming, MM method, morphology analysis and lateral thinking, cases of VE of construction industry.

  1. VE of construction industry

    International Nuclear Information System (INIS)

    1987-10-01

    This book gives descriptions of basic of VE of construction industry including doing away with mannerism, necessity of cost reduction, management method of cost reduction, thinking of idea, target of VE, starting VE activity, technical method of VE of construction industry such as thinking of idea with brainstorming, function trade method, new brainstorming, MM method, morphology analysis and lateral thinking, cases of VE of construction industry.

  2. VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

    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: dobos@konkoly.hu [Department of Astrophysical Sciences, Princeton University, 08544, 4 Ivy Lane, Peyton Hall, Princeton, NJ (United States)

    2015-05-01

    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.

  3. VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

    International Nuclear Information System (INIS)

    Dobos, Vera; Turner, Edwin L.

    2015-01-01

    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

  4. The effects of tidal range on saltmarsh morphology

    Science.gov (United States)

    Goodwin, Guillaume; Mudd, Simon

    2017-04-01

    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.

  5. Lower tidal volume strategy (≈3 ml/kg) combined with extracorporeal CO2 removal versus 'conventional' protective ventilation (6 ml/kg) in severe ARDS: the prospective randomized Xtravent-study.

    Science.gov (United States)

    Bein, Thomas; Weber-Carstens, Steffen; Goldmann, Anton; Müller, Thomas; Staudinger, Thomas; Brederlau, Jörg; Muellenbach, Ralf; Dembinski, Rolf; Graf, Bernhard M; Wewalka, Marlene; Philipp, Alois; Wernecke, Klaus-Dieter; Lubnow, Matthias; Slutsky, Arthur S

    2013-05-01

    Acute respiratory distress syndrome is characterized by damage to the lung caused by various insults, including ventilation itself, and tidal hyperinflation can lead to ventilator induced lung injury (VILI). We investigated the effects of a low tidal volume (V(T)) strategy (V(T) ≈ 3 ml/kg/predicted body weight [PBW]) using pumpless extracorporeal lung assist in established ARDS. Seventy-nine patients were enrolled after a 'stabilization period' (24 h with optimized therapy and high PEEP). They were randomly assigned to receive a low V(T) ventilation (≈3 ml/kg) combined with extracorporeal CO2 elimination, or to a ARDSNet strategy (≈6 ml/kg) without the extracorporeal device. The primary outcome was the 28-days and 60-days ventilator-free days (VFD). Secondary outcome parameters were respiratory mechanics, gas exchange, analgesic/sedation use, complications and hospital mortality. Ventilation with very low V(T)'s was easy to implement with extracorporeal CO2-removal. VFD's within 60 days were not different between the study group (33.2 ± 20) and the control group (29.2 ± 21, p = 0.469), but in more hypoxemic patients (PaO2/FIO2 ≤150) a post hoc analysis demonstrated significant improved VFD-60 in study patients (40.9 ± 12.8) compared to control (28.2 ± 16.4, p = 0.033). The mortality rate was low (16.5%) and did not differ between groups. The use of very low V(T) combined with extracorporeal CO2 removal has the potential to further reduce VILI compared with a 'normal' lung protective management. Whether this strategy will improve survival in ARDS patients remains to be determined (Clinical trials NCT 00538928).

  6. A system shift in tidal choking due to the construction of Yangshan Harbour, Shanghai, China

    Science.gov (United States)

    Guo, Wenyun; Wang, Xiao Hua; Ding, Pingxing; Ge, Jianzhong; Song, Dehai

    2018-06-01

    Tidal choking is a geometric feature caused by a narrowed channel. Construction of the Yangshan Harbour, Shanghai, China obstructed three key channels and intensively changed the local geometry and topography. In this study nine numerical experiments based on the Finite-Volume Community Ocean Model are conducted to study the project's influence on tidal characteristics. Results show that stronger tidal choking happened at the East Entrance after project, mainly due to the jet induced water-level drop forced by Bernoulli law and the longer and narrower geometry. The stronger tidal choking forces a faster flow and larger tidal energy flux at the choked channel while reducing the tidal amplitude in the Inner Harbour Area (IHA). The scouring on this channel reduces the choking effect but further enlarges tidal energy flux. Moreover, damming the channels decrease the tidal amplitude at the lee side of tidal propagating direction while increasing the amplitude on the stoss side. The dams also decrease the tidal current on both sides, and meanwhile develop two patches with stronger current aside the dam. The project induced changes in tidal characteristics are complex in space, and perturbations in bathymetry increase this complexity. Yangshan Harbour's construction induces little changes in the total tidal energy density in the IHA, but induces obvious changes in the spatial distribution of tidal energy. Although this study is site-specific, the findings may be applicable to tidal dynamics in land reclamation close to open seas, such as the dramatic reclamation of islands in the South China Sea.

  7. Grey matter volumes in treatment naïve vs. chronically treated children with attention deficit/hyperactivity disorder: a combined approach.

    Science.gov (United States)

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

    2015-08-01

    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.

  8. Tidal alignment of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš

    2015-08-01

    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.

  9. Production process of VE

    International Nuclear Information System (INIS)

    1987-07-01

    This book tells of synopsis of production process of VE(value engineering), object selection method and establishment of target, collection of object information, design of function, write improvement suggestion, evaluation of improvement suggestion, all sorts of worksheets of production process of VE, explanation of IE, explanation of PERT.

  10. 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

    Directory of Open Access Journals (Sweden)

    Josy Davidson

    2008-03-01

    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.

  11. Tidally Heated Terrestrial Exoplanets

    Science.gov (United States)

    Henning, Wade Garrett

    This work models the surface and internal temperatures for hypothetical terrestrial planets in situations involving extreme tidal heating. The feasibility of such planets is evaluated in terms of the orbital perturbations that may give rise to them, their required proximity to a hoststar, and the potential for the input tidal heating to cause significant partial melting of the mantle. Trapping terrestrial planets into 2:1 resonances with migrating Hot Jupiters is considered as a reasonable way for Earth-like worlds to both maintain high eccentricities and to move to short enough orbital periods (1-20 days) for extreme tidal heating to occur. Secular resonance and secular orbital perturbations may support moderate tidal heating at a low equilibrium eccentricity. At orbital periods below 10-30 days, with eccentricities from 0.01 to 0.1, tidal heat may greatly exceed radiogenic heat production. It is unlikely to exceed insolation, except when orbiting very low luminosity hosts, and thus will have limited surface temperature expression. Observations of such bodies many not be able to detect tidal surface enhancements given a few percent uncertainty in albedo, except on the nightside of spin synchronous airless objects. Otherwise detection may occur via spectral detection of hotspots or high volcanic gas concentrations including sulfur dioxide and hydrogen sulfide. The most extreme cases may be able to produce magma oceans, or magma slush mantles with up to 40-60% melt fractions. Tides may alter the habitable zones for smaller red dwarf stars, but are generally detrimental. Multiple viscoelastic models, including the Maxwell, Voigt-Kelvin, Standard Anelastic Solid, and Burgers rheologies are explored and applied to objects such as Io and the super-Earth planet GJ 876d. The complex valued Love number for the Burgers rheology is derived and found to be a useful improvement when modeling the low temperature behavior of tidal bodies, particularly during low eccentricity

  12. Limiting volume with modern ventilators.

    Science.gov (United States)

    Wing, Thomas J; Haan, Lutana; Ashworth, Lonny J; Anderson, Jeff

    2015-06-01

    The acute respiratory distress syndrome (ARDS) network low tidal-volume study comparing tidal volumes of 12 ml/kg versus 6 ml/kg was published in 2000. The study was stopped early as data revealed a 22% relative reduction in mortality rate when using 6 ml/kg tidal volume. The current generation of critical care ventilators allows the tidal volume to be set during volume-targeted, assist/control (volume A/C); however, some ventilators include options that may prevent the tidal volume from being controlled. The purpose of this bench study was to evaluate the delivered tidal volume, when these options are active, in a spontaneously breathing lung model using an electronic breathing simulator. Four ventilators were evaluated: CareFusion AVEA (AVEA), Dräger Evita® XL (Evita XL), Covidien Puritan Bennett® 840(TM) (PB 840), and Maquet SERVO-i (SERVO-i). Each ventilator was connected to the Hans Rudolph Electronic Breathing Simulator at an amplitude of 0 cm H2O and then 10 cm H2O. All four ventilators were set to deliver volume A/C, tidal volume 400 ml, respiratory rate 20 bpm, positive end-expiratory pressure 5 cm H2O, peak flowrate 60 L/min. The displayed tidal volume was recorded for each ventilator at the above settings with additional options OFF and then ON. The AVEA has two options in volume A/C: demand breaths and V-sync. When activated, these options allow the patient to exceed the set tidal volume. When using the Evita XL, the option AutoFlow can be turned ON or OFF, and when this option is ON, the tidal volume may vary. The PB 840 does not have any additional options that affect volume delivery, and it maintains the set tidal volume regardless of patient effort. The SERVO-i's demand valve allows additional flow if the patient's inspiratory flowrate exceeds the set flowrate, increasing the delivered tidal volume; this option can be turned OFF with the latest software upgrade. Modern ventilators have an increasing number of optional settings. These settings may

  13. Kayalarda Delme ve Patlama

    OpenAIRE

    ÖZDOĞAN, Metin

    1986-01-01

    Bu makalede açık işletmecilikte delme ve patlatma işlemlerinin günümüzdeki kuramsal ve pratik durumu sunulmaktadır. Kayanın mekanik olarak parçalanması bölümünde vurmalı ve dönmeli delme dizgeleri verilmiştir. Kayanın devinik olarak parçalanması başlığı altında ise patlatma incelenmiş ve patlatma işlemini etkileyen etmenler, patlatma kuşakları, yansıma kuramı, krater deneylerine değinilmiştir

  14. Coastal inlets and tidal basins

    NARCIS (Netherlands)

    De Vriend, H.J.; Dronkers, J.; Stive, M.J.F.; Van Dongeren, A.; Wang, J.H.

    2002-01-01

    lecture note: Tidal inlets and their associated basins (lagoons) are a common feature of lowland coasts all around the world. A significant part ofthe world's coastlines is formed by barrier island coasts, and most other tidal coasts are interrupted by estuaries and lagoon inlets. These tidal

  15. The VE/CAD synergism

    International Nuclear Information System (INIS)

    Sperling, R.B.

    1993-01-01

    Value Engineering (VE) and Computer-Aided Design (CAD) can be used synergistically to reduce costs and improve facilities designs. The cost and schedule impacts of implementing alternative design ideas developed by VE teams can be greatly reduced when the drawings have been produced with interactive CAD systems. To better understand the interrelationship between VE and CAD, the fundamentals of the VE process are explained; and example of a VE proposal is described and the way CAD drawings facilitated its implementation is illustrated

  16. Tidal residual current and its role in the mean flow on the Changjiang Bank

    Science.gov (United States)

    Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

    2016-02-01

    The tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model. The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidal residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and on the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.

  17. Tidal residual current and its role in the mean flow on the Changjiang Bank

    Energy Technology Data Exchange (ETDEWEB)

    Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

    2016-02-01

    Tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model). The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidal residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and at the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.

  18. 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.

    Science.gov (United States)

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

    2014-10-01

    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.

  19. Modeling In-stream Tidal Energy Extraction and Its Potential Environmental Impacts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Wang, Taiping; Copping, Andrea; Geerlofs, Simon H.

    2014-09-30

    In recent years, there has been growing interest in harnessing in-stream tidal energy in response to concerns of increasing energy demand and to mitigate climate change impacts. While many studies have been conducted to assess and map tidal energy resources, efforts for quantifying the associated potential environmental impacts have been limited. This paper presents the development of a tidal turbine module within a three-dimensional unstructured-grid coastal ocean model and its application for assessing the potential environmental impacts associated with tidal energy extraction. The model is used to investigate in-stream tidal energy extraction and associated impacts on estuarine hydrodynamic and biological processes in a tidally dominant estuary. A series of numerical experiments with varying numbers and configurations of turbines installed in an idealized estuary were carried out to assess the changes in the hydrodynamics and biological processes due to tidal energy extraction. Model results indicated that a large number of turbines are required to extract the maximum tidal energy and cause significant reduction of the volume flux. Preliminary model results also indicate that extraction of tidal energy increases vertical mixing and decreases flushing rate in a stratified estuary. The tidal turbine model was applied to simulate tidal energy extraction in Puget Sound, a large fjord-like estuary in the Pacific Northwest coast.

  20. Dissipation of Tidal Energy

    Science.gov (United States)

    2002-01-01

    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

  1. VE for innovative cost reduction

    International Nuclear Information System (INIS)

    1987-07-01

    This book deals with goal of value engineering characteristic of development details and development background of VE, the reason that VE is well appreciated, steps of VE process such as collection of basic information, selection of theme, organization of optimum team, item plan, function design, estimation and explanation of search result of values, item design, practical plan of innovative issue, VE reference data, and development of creative power.

  2. Tidal Venuses: triggering a climate catastrophe via tidal heating.

    Science.gov (United States)

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

    2013-03-01

    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 massesplanet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water 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.

  3. Ebb-tidal delta morphology in response to a storm surge barrier

    NARCIS (Netherlands)

    Eelkema, M.; Wang, Z.B.; Hibma, A.

    2012-01-01

    The Eastern Scheldt ebb-tidal delta morphology has been adapting for the past 25 years in response to the construction of the Eastern Scheldt storm-surge barrier in 1986. As a result of the barrier, there has been a decrease in tidal amplitudes, volumes, and average flow velocities, and there is

  4. 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

    2014-03-31

    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.

  5. Sedimentary structures of tidal flats

    Indian Academy of Sciences (India)

    Sedimentary structures of some coastal tropical tidal flats of the east coast of India, and inner estuarine tidal point bars located at 30 to 50 kilometers inland from the coast, have been extensively studied under varying seasonal conditions. The results reveal that physical features such as flaser bedding, herringbone ...

  6. Tidal heating in multilayered terrestrial exoplanets

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

    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.

  7. Tidal Heating in Multilayered Terrestrial Exoplanets

    Science.gov (United States)

    Henning, Wade G.; Hurford, Terry

    2014-01-01

    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.

  8. Tidal heating in multilayered terrestrial exoplanets

    International Nuclear Information System (INIS)

    Henning, Wade G.; Hurford, Terry

    2014-01-01

    The internal pattern and overall magnitude of tidal heating for spin-synchronous terrestrial exoplanets from 1 to 2.5 R 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.

  9. Tidal energy in France

    International Nuclear Information System (INIS)

    Lemperiere, F.

    2010-01-01

    The author first discusses the potential theoretical production of tidal energy in the world and more particularly in France, and compares this potential production with that of hydroelectric energy. He discusses the existence of potentially interesting sites in France in terms of sizing and exploitation modes. He describes the main associated works for turbines and sea walls, impacts on the environment, on the economy and on employment. He discusses the production possibilities and their cost, and the issue of energy storage. He indicates sites which could be built before 2025: Saint-Brieuc, Portbail-Coutainville or Granville, Mers or Cayeux, Penly or Saint-Valery en Caux. For each of this site, the author describes the project implantation, gives an gross assessment of the construction cost, and therefore of the kWh cost

  10. Tidal energy site - Tidal energy site mammal/bird survey

    Data.gov (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...

  11. Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

    Science.gov (United States)

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

    2013-01-01

    Abstract 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 massestidal heating. We have applied these concepts to Gl 667C c, a ∼4.5 MEarth planet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water 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. Key Words: Extrasolar terrestrial planets—Habitability—Habitable zone

  12. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

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

    2015-01-01

    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...

  13. Tidal Creek Sentinel Habitat Database

    Data.gov (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...

  14. Tidal locking of habitable exoplanets

    Science.gov (United States)

    Barnes, Rory

    2017-12-01

    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

  15. High-resolution modeling assessment of tidal stream resource in Western Passage of Maine, USA

    Science.gov (United States)

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

    2017-04-01

    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.

  16. Simple Tidal Prism Models Revisited

    Science.gov (United States)

    Luketina, D.

    1998-01-01

    Simple tidal prism models for well-mixed estuaries have been in use for some time and are discussed in most text books on estuaries. The appeal of this model is its simplicity. However, there are several flaws in the logic behind the model. These flaws are pointed out and a more theoretically correct simple tidal prism model is derived. In doing so, it is made clear which effects can, in theory, be neglected and which can not.

  17. Impact of intertidal area characteristics on estuarine tidal hydrodynamics: A modelling study for the Scheldt Estuary

    Science.gov (United States)

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

    2017-11-01

    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

  18. Policy for tidal energy

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, T L

    1977-01-01

    The potential of tidal energy for the United Kingdom should be reassessed, it is argued, and some of its advantages are cited. The technology for its development is available and proven; experience suggests that the capital works will have an indefinite life, with only the turbine blades needing to be replaced occasionally. It is a source of water power, and can be regulated to generate when required, on a flexible basis and only by day if so desired; this compares favorably with the relatively unpredictable nature of the other sources. It can be made to complement directly, and so to improve the performance of the coal and nuclear sources at a scale readily possible from a proportionately small installed capacity. The fuel is free. Present indications unquestionably suggest that it will be timely to reassess this source as part of the present energy review, so that its potential may be realized when needed after 1990. It is especially significant that the environmental effects of the necessary works appear to be comparatively small whereas the industrial and social rewards, so far not financially quantified, could be appreciable. The disadvantages that have been expressed are cited, but the author counters the attack on them. (MCW)

  19. Tidal interaction of galaxies

    International Nuclear Information System (INIS)

    Kozlov, N.N.; Syunyaev, R.A.; Ehneev, T.M.

    1974-01-01

    One of the hypotheses explaining the occurrence of anomalous details in interacting galaxies has been investigated. Pairs of galaxies with 'tails' oppositely directed or neighbouring galaxies with cofferdams 'bridges', as if connecting the galaxies, are called interacting galaxies. The hypothesis connects the origin of cofferdams and 'tails' of interacting galaxies with tidal effects ; the action of power gravitational forces in the intergalactic space. A source of such forces may be neighbouring stellar systems or invisible bodies, for instance, 'dead' quasars after a gravitational collapse. The effect of large masses of matter on the galaxy evolution has been investigated in the Institute of Applied Mathematics of the Academy of Sciences of the USSSR in 1971-1972 by numerical simulation of the process on a digital computer with the subsequent data transmission on a display. Different versions of a massive body flight relative to a galaxy disk are considered. Photographs of a display screen at different moments of time are presented. As a result of mathematical simulation of galaxies gravitational interactions effects are discovered which resemble real structures in photographs of galaxies. It seems to be premature to state that namely these mechanisms cause the formation of 'tails' and cofferdams between galaxies. However, even now it is clear that the gravitational interaction strongly affects the dynamics of the stellar system evolution. Further studies should ascertain a true scale of this effect and its genuine role in galaxy evolution

  20. Widespread infilling of tidal channels and navigable waterways in human-modified tidal deltaplain of southwest Bangladesh

    Directory of Open Access Journals (Sweden)

    Carol Wilson

    2017-12-01

    Full Text Available Since the 1960s, ~5000 km2 of tidal deltaplain in southwest Bangladesh has been embanked and converted to densely inhabited, agricultural islands (i.e., polders. This landscape is juxtaposed to the adjacent Sundarbans, a pristine mangrove forest, both well connected by a dense network of tidal channels that effectively convey water and sediment throughout the region. The extensive embanking in poldered areas, however, has greatly reduced the tidal prism (i.e., volume of water transported through local channels. We reveal that >600 km of these major waterways have infilled in recent decades, converting to land through enhanced sedimentation and the direct blocking of waterways by embankments and sluice gates. Nearly all of the observed closures (~98% have occurred along the embanked polder systems, with no comparable changes occurring in channels of the Sundarbans (<2% change. We attribute most of the channel infilling to the local reduction of tidal prism in poldered areas and the associated decline in current velocities. The infilled channels account for ~90 km2 of new land in the last 40–50 years, the rate of which, ~2 km2/yr, offsets the 4 km2/yr that is eroded at the coast, and is equivalent to ~20% of the new land produced naturally at the Ganges-Brahmaputra tidal rivermouth. Most of this new land, called ‘khas’ in Bengali, has been reclaimed for agriculture or aquaculture, contributing to the local economy. However, benefits are tempered by the loss of navigable waterways for commerce, transportation, and fishing, as well as the forced rerouting of tidal waters and sediments necessary to sustain this low-lying landscape against rising sea level. A more sustainable delta will require detailed knowledge of the consequences of these hydrodynamic changes to support more scientifically-grounded management of water, sediment, and tidal energy distribution.

  1. A life-cycle model for wave-dominated tidal inlets along passive margin coasts of North America

    Science.gov (United States)

    Seminack, Christopher T.; McBride, Randolph A.

    2018-03-01

    A regional overview of 107 wave-dominated tidal inlets along the U.S. Atlantic coast, U.S. Gulf of Mexico coast, and Canadian Gulf of St. Lawrence coast yielded a generalized wave-dominated tidal inlet life-cycle model that recognized the rotational nature of tidal inlets. Tidal inlets are influenced by concurrently acting processes transpiring over two timescales: short-term, event-driven processes and long-term, evolutionary processes. Wave-dominated tidal inlets are classified into three rotational categories based on net longshore sediment transport direction and rotation direction along the landward (back-barrier) portion of the inlet channel: downdrift channel rotation, updrift channel rotation, or little-to-no channel rotation. Lateral shifting of the flood-tidal delta depocenter in response to available estuarine accommodation space appears to control inlet channel rotation. Flood-tidal delta deposits fill accommodation space locally within the estuary (i.e., creating bathymetric highs), causing the tidal-inlet channel to rotate. External influences, such as fluvial discharge, pre-existing back-barrier channels, and impeding salt marsh will also influence inlet-channel rotation. Storm events may rejuvenate the tidal inlet by scouring sediment within the flood-tidal delta, increasing local accommodation space. Wave-dominated tidal inlets are generally unstable and tend to open, concurrently migrate laterally and rotate, infill, and close. Channel rotation is a primary reason for wave-dominated tidal inlet closure. During rotation, the inlet channel lengthens and hydraulic efficiency decreases, thus causing tidal prism to decrease. Tidal prism, estuarine accommodation space, and sediment supply to the flood-tidal delta are the primary variables responsible for tidal inlet rotation. Stability of wave-dominated tidal inlets is further explained by: stability (S) = tidal prism (Ω) + estuarine accommodation space (V) - volume of annual sediment supply (Mt

  2. The economics of tidal energy

    International Nuclear Information System (INIS)

    Denny, Eleanor

    2009-01-01

    Concern over global climate change has led policy makers to accept the importance of reducing greenhouse gas emissions. This in turn has led to a large growth in clean renewable generation for electricity production. Much emphasis has been on wind generation as it is among the most advanced forms of renewable generation, however, its variable and relatively unpredictable nature result in increased challenges for electricity system operators. Tidal generation on the other hand is almost perfectly forecastable and as such may be a viable alternative to wind generation. This paper calculates the break-even capital cost for tidal generation on a real electricity system. An electricity market model is used to determine the impact of tidal generation on the operating schedules of the conventional units on the system and on the resulting cycling costs, emissions and fuel savings. It is found that for tidal generation to produce positive net benefits for the case study, the capital costs would have to be less than Euro 510,000 per MW installed which is currently an unrealistically low capital cost. Thus, it is concluded that tidal generation is not a viable option for the case system at the present time.

  3. Remnants of strong tidal interactions

    International Nuclear Information System (INIS)

    Mcglynn, T.A.

    1990-01-01

    This paper examines the properties of stellar systems that have recently undergone a strong tidal shock, i.e., a shock which removes a significant fraction of the particles in the system, and where the shocked system has a much smaller mass than the producer of the tidal field. N-body calculations of King models shocked in a variety of ways are performed, and the consequences of the shocks are investigated. The results confirm the prediction of Jaffe for shocked systems. Several models are also run where the tidal forces on the system are constant, simulating a circular orbit around a primary, and the development of tidal radii under these static conditions appears to be a mild process which does not dramatically affect material that is not stripped. The tidal radii are about twice as large as classical formulas would predict. Remnant density profiles are compared with a sample of elliptical galaxies, and the implications of the results for the development of stellar populations and galaxies are considered. 38 refs

  4. TIDAL LIMITS TO PLANETARY HABITABILITY

    International Nuclear Information System (INIS)

    Barnes, Rory; Jackson, Brian; Greenberg, Richard; Raymond, Sean N.

    2009-01-01

    The habitable zones (HZs) of main-sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurfaces the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO 2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with the range of the traditional HZ for main-sequence, low-mass stars. We propose a revised HZ that incorporates both stellar insolation and tidal heating. We apply these criteria to GJ 581 d and find that it is in the traditional HZ, but its tidal heating alone may be insufficient for plate tectonics.

  5. Tidal ventilation distribution during pressure-controlled ventilation and pressure support ventilation in post-cardiac surgery patients.

    Science.gov (United States)

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

    2014-09-01

    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 (tidal volumes (≥ 8 ml/kg). In addition, the distribution of tidal 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.

  6. Tidal variations of earth rotation

    Science.gov (United States)

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

    1981-01-01

    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.

  7. The Origin of Faint Tidal Features around Galaxies in the RESOLVE Survey

    Science.gov (United States)

    Hood, Callie E.; Kannappan, Sheila J.; Stark, David V.; Dell’Antonio, Ian P.; Moffett, Amanda J.; Eckert, Kathleen D.; Norris, Mark A.; Hendel, David

    2018-04-01

    We study tidal features around galaxies in the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. Our sample consists of 1048 RESOLVE galaxies that overlap with the DECam Legacy Survey, which reaches an r-band 3σ depth of ∼27.9 mag arcsec‑2 for a 100 arcsec2 feature. Images were masked, smoothed, and inspected for tidal features such as streams, shells, or tails/arms. We find tidal features in 17±2% of our galaxies, setting a lower limit on the true frequency. The frequency of tidal features in the gas-poor (gas-to-stellar mass ratio arms from resonant interactions. Similar to tidal features in gas-poor galaxies, tidal features in gas-rich galaxies imply 1.7× closer nearest neighbors in the same group; however, they are associated with diskier morphologies, higher star formation rates, and higher gas content. In addition to interactions with known neighbors, we suggest that tidal features in gas-rich galaxies may arise from accretion of cosmic gas and/or gas-rich satellites below the survey limit.

  8. The distribution and tapping tidal energy

    Directory of Open Access Journals (Sweden)

    Zygmunt Kowalik

    2004-09-01

    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

  9. Turning the tide : tidal power in the UK

    OpenAIRE

    Sustainable Development Commission

    2007-01-01

    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 ...

  10. Facies architecture of heterolithic tidal deposits : The Holocene Holland Tidal Basin

    NARCIS (Netherlands)

    Donselaar, M.E.; Geel, C.R.

    2007-01-01

    The size, shape and spatial position of lithofacies types (or facies architecture) in a tidal estuarine basin are complex and therefore difficult to model. The tidal currents in the basin concentrate sand-sized sediment in a branching pattern of tidal channels and fringing tidal flats. Away from the

  11. Tidal flow separation at protruding beach nourishments

    NARCIS (Netherlands)

    Radermacher, M.; de Schipper, M.A.; Swinkels, Cilia M.; MacMahan, Jamie; Reniers, A.J.H.M.

    2016-01-01

    In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal

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

    Science.gov (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. Tidal energy - a technology review

    International Nuclear Information System (INIS)

    Price, R.

    1991-01-01

    The tides are caused by gravitational attraction of the sun and the moon acting upon the world's oceans. This creates a clean renewable form of energy which can in principle be tapped for the benefit of mankind. This paper reviews the status of tidal energy, including the magnitude of the resource, the technology which is available for its extraction, the economics, possible environmental effects and non-technical barriers to its implementation. Although the total energy flux of the tides is large, at about 2 TW, in practice only a very small fraction of this total potential can be utilised in the foreseeable future. This is because the energy is spread diffusely over a wide area, requiring large and expensive plant for its collection, and is often available remote from centres of consumption. The best mechanism for exploiting tidal energy is to employ estuarine barrages at suitable sites with high tidal ranges. The technology is relatively mature and components are commercially available now. Also, many of the best sites for implementation have been identified. However, the pace and extent of commercial exploitation of tidal energy is likely to be significantly influenced, both by the treatment of environmental costs of competing fossil fuels, and by the availability of construction capital at modest real interest rates. The largest projects could require the involvement of national governments if they are to succeed. (author) 8 figs., 2 tabs., 19 refs

  14. Properties of active tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Lefebvre, Alice; Becker, Marius

    2016-01-01

    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...

  15. 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

    2014-02-02

    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.

  16. PREPD O and VE remote handling system

    International Nuclear Information System (INIS)

    Theil, T.N.

    1985-01-01

    The Process Experimental Pilot Plant (PREPP) at the Idaho National Engineering Laboratory is designed for volume reduction and packaging of transuranic (TRU) waste. The PREPP opening and verification enclosure (O and VE) remote handling system, within that facility, is designed to provide examination of the contents of various TRU waste storage containers. This remote handling system will provide the means of performing a hazardous operation that is currently performed manually. The TeleRobot to be used in this system is a concept that will incorporate and develop man in the loop operation (manual mode), standardized automatic sequencing of end effector tools, increased payload and reach over currently available computer-controlled robots, and remote handling of a hazardous waste operation. The system is designed within limited space constraints and an operation that was originally planned, and is currently being manually performed at other plants. The PREPP O and VE remote handling system design incorporates advancing technology to improve the working environment in the nuclear field

  17. Dynamical modeling of tidal streams

    International Nuclear Information System (INIS)

    Bovy, Jo

    2014-01-01

    I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking advantage of the essentially one-dimensional nature of tidal streams, the transformation to position-velocity coordinates can be linearized and interpolated near a small number of points along the stream, thus allowing for efficient computations of a stream's properties in observable quantities. I illustrate how to calculate the stream's average location (its 'track') in different coordinate systems, how to quickly estimate the dispersion around its track, and how to draw mock stream data. As a generative model, this framework allows one to compute the full probability distribution function and marginalize over or condition it on certain phase-space dimensions as well as convolve it with observational uncertainties. This will be instrumental in proper data analysis of stream data. In addition to providing a computationally efficient practical tool for modeling the dynamics of tidal streams, the action-angle nature of the framework helps elucidate how the observed width of the stream relates to the velocity dispersion or mass of the progenitor, and how the progenitors of 'orphan' streams could be located. The practical usefulness of the proposed framework crucially depends on the ability to calculate action-angle variables for any orbit in any gravitational potential. A novel method for calculating actions, frequencies, and angles in any static potential using a single orbit integration is described in the Appendix.

  18. Prospects for Fundy tidal power

    International Nuclear Information System (INIS)

    Clark, R.H.

    1997-01-01

    The Bay of Fundy in Canada probably possesses the most favourable conditions in the world for the exploitation of tidal energy. The results of the comprehensive investigations carried out during the past quarter-century are reviewed together with operating and environmental aspects of the modest (20 MW) Annapolis Tidal Power Station, commissioned in 1984, the primary purpose of which was to evaluate the operation of a large (7.6 m) diameter Straflo turbine unit under low heads. The results of the operating and maintenance experience for the Annapolis Station are reviewed as well as the results of the environmental/ecological studies that have been on-going in the Annapolis Basin. The tidal power investigations have shown that a 1400 MW development at the mouth of the Cumberland Basin, at the head of the bay of Fundy, is technically and economically feasible and that its output would probably be competitive with fossil-fired plants, particularly if a 'green' accounting technique were applied to such energy sources. The importance of timing, if the exploitation of this non-polluting, renewable and completely predicable source is to be used to meet the future electrical energy needs of the maritime provinces, is discussed. (author)

  19. Numerical calculation of hydrodynamic characteristics of tidal currents for submarine excavation engineering in coastal area

    Directory of Open Access Journals (Sweden)

    Jian-hua Li

    2016-04-01

    Full Text Available In coastal areas with complicated flow movement, deposition and scour readily occur in submarine excavation projects. In this study, a small-scale model, with a high resolution in the vertical direction, was used to simulate the tidal current around a submarine excavation project. The finite volume method was used to solve Navier-Stokes equations and the Reynolds stress transport equation, and the entire process of the tidal current was simulated with unstructured meshes, generated in the irregular shape area, and structured meshes, generated in other water areas. The meshes near the bottom and free surface were densified with a minimum layer thickness of 0.05 m. The volume of fluid method was used to track the free surface, the volume fraction of cells on the upstream boundary was obtained from the volume fraction of adjacent cells, and that on the downstream boundary was determined by the water level process. The numerical results agree with the observed data, and some conclusions can be drawn: after the foundation trench excavation, the flow velocity decreases quite a bit through the foundation trench, with reverse flow occurring on the lee slope in the foundation trench; the swirling flow impedes inflow, leading to the occurrence of dammed water above the foundation trench; the turbulent motion is stronger during ebbing than in other tidal stages, the range with the maximum value of turbulent viscosity, occurring on the south side of the foundation trench at maximum ebbing, is greater than those in other tidal stages in a tidal cycle, and the maximum value of Reynolds shear stress occurs on the south side of the foundation trench at maximum ebbing in a tidal cycle. The numerical calculation method shows a strong performance in simulation of the hydrodynamic characteristics of tidal currents in the foundation trench, providing a basis for submarine engineering construction in coastal areas.

  20. Modeling Interactions between Backbarrier Marshes, Tidal Inlets, Ebb-deltas, and Adjacent Barriers Exposed to Rising Sea Levels

    Science.gov (United States)

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

    2016-02-01

    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

  1. Calculating residual flows through a multiple-inlet system: the conundrum of the tidal period

    Science.gov (United States)

    Duran-Matute, Matias; Gerkema, Theo

    2015-11-01

    The concept of residual, i.e., tidally-averaged, flows through a multiple inlet system is reappraised. The evaluation of the residual through-flow depends on the time interval over which is integrated, in other words, on how one defines the tidal period. It is demonstrated that this definition is ambiguous and that different definitions (based on, e.g., high waters, slack tides, etc.) yield very different results for the residual, also in terms of their long-term statistical properties (median and standard deviation). A basin-wide applicable method of defining the tidal period, in terms of enclosed water volume, is analyzed. We compare the different methods on the basis of high-resolution model results for the Western Dutch Wadden Sea. The multitude of tidal constituents together with wind variability creates broad distributions for the residuals, with standard deviations much larger than the mean or median residual flows.

  2. TIDAL FRICTION AND TIDAL LAGGING. APPLICABILITY LIMITATIONS OF A POPULAR FORMULA FOR THE TIDAL TORQUE

    International Nuclear Information System (INIS)

    Efroimsky, Michael; Makarov, Valeri V.

    2013-01-01

    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.

  3. TIDAL FRICTION AND TIDAL LAGGING. APPLICABILITY LIMITATIONS OF A POPULAR FORMULA FOR THE TIDAL TORQUE

    Energy Technology Data Exchange (ETDEWEB)

    Efroimsky, Michael; Makarov, Valeri V., E-mail: michael.efroimsky@usno.navy.mil, E-mail: vvm@usno.navy.mil [US Naval Observatory, Washington, DC 20392 (United States)

    2013-02-10

    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.

  4. TIDAL NOVAE IN COMPACT BINARY WHITE DWARFS

    International Nuclear Information System (INIS)

    Fuller, Jim; Lai Dong

    2012-01-01

    Compact binary white dwarfs (WDs) undergoing orbital decay due to gravitational radiation can experience significant tidal heating prior to merger. In these WDs, the dominant tidal effect involves the excitation of outgoing gravity waves in the inner stellar envelope and the dissipation of these waves in the outer envelope. As the binary orbit decays, the WDs are synchronized from outside in (with the envelope synchronized first, followed by the core). We examine the deposition of tidal heat in the envelope of a carbon-oxygen WD and study how such tidal heating affects the structure and evolution of the WD. We show that significant tidal heating can occur in the star's degenerate hydrogen layer. This layer heats up faster than it cools, triggering runaway nuclear fusion. Such 'tidal novae' may occur in all WD binaries containing a CO WD, at orbital periods between 5 minutes and 20 minutes, and precede the final merger by 10 5 -10 6 years.

  5. 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.

    and summer monsoon seasons of year 2000. Information on tidal signals contained in the currents were extracted using harmonic analysis - Least Squares Method and non-tidal component were analyzed using the Chi sub(o) filter. The study established...

  6. 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

    2006-10-01

    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

  7. Interactions Between Wetlands and Tidal Inlets

    National Research Council Canada - National Science Library

    Sanchez, Alejandro

    2008-01-01

    This Coastal and Hydraulics Engineering Technical Note (CHETN) presents numerical simulations investigating how the loss of wetlands in estuaries modifies tidal processes in inlet navigation channels...

  8. Formation of double galaxies by tidal capture

    International Nuclear Information System (INIS)

    Alladin, S.M.; Potdar, A.; Sastry, K.S.

    1975-01-01

    The conditions under which double galaxies may be formed by tidal capture are considered. Estimates for the increase in the internal energy of colliding galaxies due to tidal effects are used to determine the magnitudes Vsub(cap) and Vsub(dis) of the maximum relative velocities at infinite separation required for tidal capture and tidal disruption respectively. A double galaxy will be formed by tidal capture without tidal disruption of a component if Vsub(cap)>Vsub(i) and Vsub(cap)>Vsub(dis) where Vsub(i) is the initial relative speed of the two galaxies at infinite separation. If the two galaxies are of the same dimension, formulation of double galaxies by tidal capture is possible in a close collision either if the two galaxies do not differ much in mass and density distribution or if the more massive galaxy is less centrally concentrated than the other. If it is assumed as statistics suggest, that the mass of a galaxy is proportional to the square of its radius, it follows that the probability of the formation of double galaxies by tidal capture increases with the increase in mass of the galaxies and tidal distribution does not occur in a single collision for any distance of closest approach of the two galaxies. (Auth.)

  9. Habitability from Tidally Induced Tectonics

    Science.gov (United States)

    Valencia, Diana; Tan, Vivian Yun Yan; Zajac, Zachary

    2018-04-01

    The stability of Earth’s climate on geological timescales is enabled by the carbon–silicate cycle that acts as a negative feedback mechanism stabilizing surface temperatures via the intake and outgassing of atmospheric carbon. On Earth, this thermostat is enabled by plate tectonics that sequesters outgassed CO2 back into the mantle via weathering and subduction at convergent margins. Here we propose a separate tectonic mechanism—vertical recycling—that can serve as the vehicle for CO2 outgassing and sequestration over long timescales. The mechanism requires continuous tidal heating, which makes it particularly relevant to planets in the habitable zone of M stars. Dynamical models of this vertical recycling scenario and stability analysis show that temperate climates stable over timescales of billions of years are realized for a variety of initial conditions, even as the M star dims over time. The magnitude of equilibrium surface temperatures depends on the interplay of sea weathering and outgassing, which in turn depends on planetary carbon content, so that planets with lower carbon budgets are favored for temperate conditions. The habitability of planets such as found in the Trappist-1 system may be rooted in tidally driven tectonics.

  10. The CEVALE2VE case

    CERN Document Server

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

    2017-01-01

    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...

  11. The CEVALE2VE case

    CERN Document Server

    Sanchez Pineda, Arturo; The ATLAS collaboration

    2016-01-01

    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. Tidal mixing in Dahej creek waters

    Digital Repository Service at National Institute of Oceanography (India)

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

    Mixing characteristics of a tidal inlet near Dahej at the mouth of Narmada River, Gujarat, India are examined in terms of tides, currents and bathymetry. The dilution potential of the Dahej Creek waters during a tidal march for a given rate...

  13. TIDALLY HEATED TERRESTRIAL EXOPLANETS: VISCOELASTIC RESPONSE MODELS

    International Nuclear Information System (INIS)

    Henning, Wade G.; O'Connell, Richard J.; Sasselov, Dimitar D.

    2009-01-01

    Tidal friction in exoplanet systems, driven by orbits that allow for durable nonzero eccentricities at short heliocentric periods, can generate internal heating far in excess of the conditions observed in our own solar system. Secular perturbations or a notional 2:1 resonance between a hot Earth and hot Jupiter can be used as a baseline to consider the thermal evolution of convecting bodies subject to strong viscoelastic tidal heating. We compare results first from simple models using a fixed Quality factor and Love number, and then for three different viscoelastic rheologies: the Maxwell body, the Standard Anelastic Solid (SAS), and the Burgers body. The SAS and Burgers models are shown to alter the potential for extreme tidal heating by introducing the possibility of new equilibria and multiple response peaks. We find that tidal heating tends to exceed radionuclide heating at periods below 10-30 days, and exceed insolation only below 1-2 days. Extreme cases produce enough tidal heat to initiate global-scale partial melting, and an analysis of tidal limiting mechanisms such as advective cooling for earthlike planets is discussed. To explore long-term behaviors, we map equilibria points between convective heat loss and tidal heat input as functions of eccentricity. For the periods and magnitudes discussed, we show that tidal heating, if significant, is generally detrimental to the width of habitable zones.

  14. Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

    Science.gov (United States)

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

    2011-01-01

    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

  15. Relativistic theory of tidal Love numbers

    International Nuclear Information System (INIS)

    Binnington, Taylor; Poisson, Eric

    2009-01-01

    In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. We present a relativistic theory of Love numbers, which applies to compact bodies with strong internal gravities; the theory extends and completes a recent work by Flanagan and Hinderer, which revealed that the tidal Love number of a neutron star can be measured by Earth-based gravitational-wave detectors. We consider a spherical body deformed by an external tidal field, and provide precise and meaningful definitions for electric-type and magnetic-type Love numbers; and these are computed for polytropic equations of state. The theory applies to black holes as well, and we find that the relativistic Love numbers of a nonrotating black hole are all zero.

  16. Tidal current and tidal energy changes imposed by a dynamic tidal power system in the Taiwan Strait, China

    Science.gov (United States)

    Dai, Peng; Zhang, Jisheng; Zheng, Jinhai

    2017-12-01

    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.

  17. The influence of waves on the tidal kinetic energy resource at a tidal stream energy site

    International Nuclear Information System (INIS)

    Guillou, Nicolas; Chapalain, Georges; Neill, Simon P.

    2016-01-01

    Highlights: • We model the influence of waves on tidal kinetic energy in the Fromveur Strait. • Numerical results are compared with field data of waves and currents. • The introduction of waves improve predictions of tidal stream power during storm. • Mean spring tidal stream potential is reduced by 12% during extreme wave conditions. • Potential is reduced by 7.8% with waves forces and 5.3% with enhanced friction. - Abstract: Successful deployment of tidal energy converters relies on access to accurate and high resolution numerical assessments of available tidal stream power. However, since suitable tidal stream sites are located in relatively shallow waters of the continental shelf where tidal currents are enhanced, tidal energy converters may experience effects of wind-generated surface-gravity waves. Waves may thus influence tidal currents, and associated kinetic energy, through two non-linear processes: the interaction of wave and current bottom boundary layers, and the generation of wave-induced currents. Here, we develop a three-dimensional tidal circulation model coupled with a phase-averaged wave model to quantify the impact of the waves on the tidal kinetic energy resource of the Fromveur Strait (western Brittany) - a region that has been identified with strong potential for tidal array development. Numerical results are compared with in situ observations of wave parameters (significant wave height, peak period and mean wave direction) and current amplitude and direction 10 m above the seabed (the assumed technology hub height for this region). The introduction of waves is found to improve predictions of tidal stream power at 10 m above the seabed at the measurement site in the Strait, reducing kinetic energy by up to 9% during storm conditions. Synoptic effects of wave radiation stresses and enhanced bottom friction are more specifically identified at the scale of the Strait. Waves contribute to a slight increase in the spatial gradient of

  18. Relevance of tidal heating on large TNOs

    Science.gov (United States)

    Saxena, Prabal; Renaud, Joe P.; Henning, Wade G.; Jutzi, Martin; Hurford, Terry

    2018-03-01

    We examine the relevance of tidal heating for large Trans-Neptunian Objects, with a focus on its potential to melt and maintain layers of subsurface liquid water. Depending on their past orbital evolution, tidal heating may be an important part of the heat budget for a number of discovered and hypothetical TNO systems and may enable formation of, and increased access to, subsurface liquid water. Tidal heating induced by the process of despinning is found to be particularly able to compete with heating due to radionuclide decay in a number of different scenarios. In cases where radiogenic heating alone may establish subsurface conditions for liquid water, we focus on the extent by which tidal activity lifts the depth of such conditions closer to the surface. While it is common for strong tidal heating and long lived tides to be mutually exclusive, we find this is not always the case, and highlight when these two traits occur together. We find cases where TNO systems experience tidal heating that is a significant proportion of, or greater than radiogenic heating for periods ranging from100‧s of millions to a billion years. For subsurface oceans that contain a small antifreeze component, tidal heating due to very high initial spin states may enable liquid water to be preserved right up to the present day. Of particular interest is the Eris-Dysnomia system, which in those cases may exhibit extant cryovolcanism.

  19. Atmospheric noise of a breaking tidal bore.

    Science.gov (United States)

    Chanson, Hubert

    2016-01-01

    A tidal bore is a surge of waters propagating upstream in an estuary as the tidal flow turns to rising and the flood tide propagates into a funnel-shaped system. Large tidal bores have a marked breaking roller. The sounds generated by breaking tidal bores were herein investigated in the field (Qiantang River) and in laboratory. The sound pressure record showed two dominant periods, with some similarity with an earlier study [Chanson (2009). J. Acoust. Soc. Am. 125(6), 3561-3568]. The two distinct phases were the incoming tidal bore when the sound amplitude increased with the approaching bore, and the passage of the tidal bore in front of the microphone when loud and powerful noises were heard. The dominant frequency ranged from 57 to 131 Hz in the Qiantang River bore. A comparison between laboratory and prototype tidal bores illustrated both common features and differences. The low pitch sound of the breaking bore had a dominant frequency close to the collective oscillations of bubble clouds, which could be modeled with a bubble cloud model using a transverse dimension of the bore roller. The findings suggest that this model might be over simplistic in the case of a powerful breaking bore, like that of the Qiantang River.

  20. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

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

    2017-08-01

    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.

  1. No Snowball on Habitable Tidally Locked Planets

    Energy Technology Data Exchange (ETDEWEB)

    Checlair, Jade; Abbot, Dorian S. [Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Menou, Kristen, E-mail: jadecheclair@uchicago.edu [Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4 (Canada)

    2017-08-20

    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 CO{sub 2} 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.

  2. No Snowball on Habitable Tidally Locked Planets

    International Nuclear Information System (INIS)

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

    2017-01-01

    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 CO 2 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.

  3. Kedi ve Köpeklerde Diabetes Mellitus.

    OpenAIRE

    ŞİMŞEK, Aynur; İÇEN, Hasan

    2008-01-01

    Diabetes mellitus polidipsi, poliüri ve polifaji gibi klinik bulgularla karakterize endokrin bir hastalıktır. Bu derlemede, kedi ve köpeklerde yaygın olan hastalığın etiyoloji, patogenezis, kliniklaboratuar bulguları, tanı, ayırıcı tanı ve sağaltımına yönelik bilgilerin verilmesi amaçlanmıştır

  4. 47 CFR 97.513 - VE session manager requirements.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false VE session manager requirements. 97.513 Section... SERVICES AMATEUR RADIO SERVICE Qualifying Examination Systems § 97.513 VE session manager requirements. (a) A VE session manager may be selected by the VE team for each examination session. The VE session...

  5. Tidal interactions with Kerr black holes

    International Nuclear Information System (INIS)

    Hiscock, W.A.

    1977-01-01

    The tidal deformation of an extended test body falling with zero angular momentum into a Kerr black hole is calculated. Numerical results for infall along the symmetry axis and in the equatorial plane of the black hole are presented for a range of values of a, the specific angular momentum of the black hole. Estimates of the tidal contribution to the gravitational radiation are also given. The tidal contribution in equatorial infall into a maximally rotating Kerr black hole may be of the same order as the center-of-mass contribution to the gravitational radiation

  6. Tidal influence on subtropical estuarine methane emissions

    Science.gov (United States)

    Sturm, Katrin; Grinham, Alistair; Werner, Ursula; Yuan, Zhiguo

    2014-05-01

    The relatively unstudied subtropical estuaries, particularly in the Southern Hemisphere, represent an important gap in our understanding of global greenhouse gas (GHG) emissions. These systems are likely to form an important component of GHG budgets as they occupy a relatively large surface area, over 38 000 km2 in Australia. Here, we present studies conducted in the Brisbane River estuary, a representative system within the subtropical region of Queensland, Australia. This is a highly modified system typical of 80% of Australia's estuaries. Generally, these systems have undergone channel deepening and straightening for safer shipping access and these modifications have resulted in large increases in tidal reach. The Brisbane River estuary's natural tidal reach was 16 km and this is now 85 km and tidal currents influence double the surface area (9 km2 to 18 km2) in this system. Field studies were undertaken to improve understanding of the driving factors behind methane water-air fluxes. Water-air fluxes in estuaries are usually calculated with the gas exchange coefficient (k) for currents and wind as well as the concentration difference across the water-air interface. Tidal studies in the lower and middle reaches of the estuary were performed to monitor the influence of the tidal stage (a proxy for kcurrent) on methane fluxes. Results for both investigated reaches showed significantly higher methane fluxes during the transition time of tides, the time of greatest tidal currents, than during slack tide periods. At these tidal transition times with highest methane chamber fluxes, lowest methane surface water concentrations were monitored. Modelled fluxes using only wind speed (kwind) were at least one order of magnitude lower than observed from floating chambers, demonstrating that current speed was likely the driving factor of water-air fluxes. An additional study was then conducted sampling the lower, middle and upper reaches during a tidal transition period

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

    Directory of Open Access Journals (Sweden)

    José J. Alonso del Rosario

    2006-03-01

    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.

  8. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

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

    2012-01-01

    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

  9. Development of tidal watersheds in the Wadden Sea

    NARCIS (Netherlands)

    Wang, Z.B.; Vroom, J.; van Prooijen, B.C.; Labeur, R.J.; Stive, M.J.F.; Hansen, M.H.P.

    2011-01-01

    The Wadden Sea consists of a series of tidal lagoons which are connected to the North Sea by tidal inlets. Boundaries to each lagoon are the mainland coast, the barrier islands on both sides of the tidal inlet, and the tidal watersheds behind the two barrier islands. Behind each Wadden Island there

  10. Tidal Mixing at the Shelf Break

    National Research Council Canada - National Science Library

    Hogg, Nelson; Legg, Sonya

    2005-01-01

    ...; the second a set of simulations of flow over the Hawaiian ridge. The most exciting scientific result is the importance of internal hydraulic jumps in generating tidal mixing at large amplitude, steep topography...

  11. Tidal Mixing at the Shelf Break

    National Research Council Canada - National Science Library

    Hogg, Nelson; Legg, Sonya

    2005-01-01

    The aim of this project was to study mixing forced by tidal flow over sudden changes in topographic slope such as near the shelf-break, using high-resolution nonhydrostatic numerical simulations employing the MIT gem...

  12. Microbial quality of a marine tidal pool

    CSIR Research Space (South Africa)

    Genthe, Bettina

    1995-01-01

    Full Text Available In this study the source of microbial pollution to a tidal pool was investigated. Both adjacent seawater which could contribute to possible faecal pollution and potential direct bather pollution were studied. The microbial quality of the marine...

  13. 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...

  14. Resonant Tidal Disruption in Galactic Nuclei

    OpenAIRE

    Rauch, Kevin P.; Ingalls, Brian

    1997-01-01

    It has recently been shown that the rate of angular momentum relaxation in nearly-Keplerian star clusters is greatly increased by a process termed resonant relaxation (Rauch & Tremaine 1996), who also argued that tidal disruption of stars in galactic nuclei containing massive black holes could be noticeably enhanced by this process. We describe here the results of numerical simulations of resonant tidal disruption which quantitatively test the predictions made by Rauch & Tremaine. The simulat...

  15. On the ambiguity in relativistic tidal deformability

    Science.gov (United States)

    Gralla, Samuel E.

    2018-04-01

    The LIGO collaboration recently reported the first gravitational-wave constraints on the tidal deformability of neutron stars. I discuss an inherent ambiguity in the notion of relativistic tidal deformability that, while too small to affect the present measurement, may become important in the future. I propose a new way to understand the ambiguity and discuss future prospects for reliably linking observed gravitational waveforms to compact object microphysics.

  16. WIYN Open Cluster Study: Tidal Interactions in Solar type Binaries

    OpenAIRE

    Meibom, S.; Mathieu, R. D.

    2003-01-01

    We present an ongoing study on tidal interactions in late-type close binary stars. New results on tidal circularization are combined with existing data to test and constrain theoretical predictions of tidal circularization in the pre-main-sequence (PMS) phase and throughout the main-sequence phase of stellar evolution. Current data suggest that tidal circularization during the PMS phase sets the tidal cutoff period for binary populations younger than ~1 Gyr. Binary populations older than ~1 G...

  17. Half Moon Cove Tidal Project. Feasibility report

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    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.

  18. TIDAL INTERACTIONS IN MERGING WHITE DWARF BINARIES

    International Nuclear Information System (INIS)

    Piro, Anthony L.

    2011-01-01

    The recently discovered system J0651 is the tightest known detached white dwarf (WD) binary. Since it has not yet initiated Roche-lobe overflow, it provides a relatively clean environment for testing our understanding of tidal interactions. I investigate the tidal heating of each WD, parameterized in terms of its tidal Q parameter. Assuming that the heating can be radiated efficiently, the current luminosities are consistent with Q 1 ∼ 7 x 10 10 and Q 2 ∼ 2 x 10 7 , for the He and C/O WDs, respectively. Conversely, if the observed luminosities are merely from the cooling of the WDs, these estimated values of Q represent the upper limits. A large Q 1 for the He WD means its spin velocity will be slower than that expected if it was tidally locked, which, since the binary is eclipsing, may be measurable via the Rossiter-McLaughlin effect. After one year, gravitational wave emission shifts the time of eclipses by 5.5 s, but tidal interactions cause the orbit to shrink more rapidly, changing the time by up to an additional 0.3 s after a year. Future eclipse timing measurements may therefore infer the degree of tidal locking.

  19. VE for Lua game programming

    CERN Document Server

    Mishra, Brij Bhushan

    2013-01-01

    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. Hücre siklusu ve kanser

    OpenAIRE

    Cabadak, Hülya

    2008-01-01

    Hücre çogalması ve hücre siklusunun ilerlemesi büyümenin kontrolünde rolü olan genlerin ekspresyonu ile baglantılıdır. Ökaryot hücre siklusuM(mitoz) G , S ve G fazlarından olusmaktadır. Bu süreçte hücre uyarımı ve büyüme meydana gelir veya hücre G fazında durmaktadır. Hücre siklusunda G -S geçisinde, G -Mgeçisinde ve metafaz-anafaz geçisinde kontrol noktaları bulunmaktadır. Hücre siklusu siklin bagımlı kinazlar (cdk, katalitik altbirim) ve siklin (cyc, düzenleyici altbirim) tarafı...

  1. Mo(ve)ment-methodology

    DEFF Research Database (Denmark)

    Mørck, Line Lerche; Christian Celosse-Andersen, Martin

    2018-01-01

    This paper describes the theoretical basis for and development of a moment-movement research methodology, based on an integration of critical psychological practice research and critical ethnographic social practice theory. Central theoretical conceptualizations, such as human agency, life...... conditions and identity formation, are discussed in relation to criminological theories of gang desistance. The paper illustrates how the mo(ve)ment methodology was applied in a study of comprehensive processes of identity (re)formation and gang exit processes. This study was conducted with Martin, a former....... This is a moment which captures Martin’s complex and ambiguous feelings of conflictual concerns, frustration, anger, and a new feeling of insecurity in his masculinity, as well as engagement and a sense of deep meaningfulness as he becomes a more reflective academic. All these conflicting feelings also give...

  2. Genève Reconnaissante

    CERN Multimedia

    2001-01-01

    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. Plant distributions along salinity and tidal gradients in Oregon tidal marshes

    Science.gov (United States)

    Accurately modeling climate change effects on tidal marshes in the Pacific Northwest requires understanding how plant assemblages and species are presently distributed along gradients of salinity and tidal inundation. We outline on-going field efforts by the EPA and USGS to dete...

  4. Tidal exchange between a freshwater tidal marsh and an impacted estuary: the Scheldt estuary, Belgium

    NARCIS (Netherlands)

    van Damme, S.; Dehairs, F.; Tackx, M.; Beauchard, O.; Struyf, E.; Gribsholt, B.; van Cleemput, O.; Meire, P.

    2009-01-01

    Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a

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

    NARCIS (Netherlands)

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

    2014-01-01

    The net transport of sediment between the back-barrier basin and the sea is an important process for determining the stability of tidal inlet systems. Earlier studies showed that in a short basin, tidal flats favor peak ebb-currents stronger than peak flood currents, implying export of coarse

  6. 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.

    are predominantly mixed, semidiurnal in nature. Motion over any continental shelf is governed by the tide-driven oscillatory flow. In this paper, tidal and non-tidal characteristics of the waters of Southwest continental shelf of India are assessed using...

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

    CERN Document Server

    Carlin, Jeffrey

    2016-01-01

    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...

  8. Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing.

    Science.gov (United States)

    Koulouris, N G; Latsi, P; Dimitroulis, J; Jordanoglou, B; Gaga, M; Jordanoglou, J

    2001-06-01

    The lack of methodology for measuring the alveolar carbon dioxide tension (PA,CO2) has forced investigators to make several assumptions, such as that PA,CO2 is equal to end-tidal (PET,CO2) and arterial CO2 tension (Pa,CO2). The present study measured the mean PA,CO2 and Bohr's dead space ratio (Bohr's dead space/tidal volume (VD,Bohr/VT)) during tidal breathing. The method used is a new, simple and noninvasive technique, based on the analysis of the expired CO2 volume per breath (VCO2) versus the exhaled VT. This curve was analysed in 21 normal, healthy subjects and 35 chronic obstructive pulmonary disease (COPD) patients breathing tidally through a mouthpiece apparatus in the sitting position. It is shown that: 1) PA,CO2 is similar to Pa,CO2 in normal subjects, whilst it is significantly lower than Pa,CO2 in COPD patients; 2) PA,CO2 is significantly higher than PET,CO2 in all subjects, especially in COPD patients; 3) VD,Bohr/VT is increased in COPD patients as compared to normal subjects; and 4) VD,Bohr/VT is lower than the "physiological" dead space ratio (VD,phys/VT) in COPD patients. It is concluded that the expired carbon dioxide versus tidal volume curve is a useful tool for research and clinical work, because it permits the noninvasive and accurate measurement of Bohr's dead space and mean alveolar carbon dioxide tension accurately during spontaneous breathing.

  9. Use of tidal breathing curves for evaluating expiratory airway obstruction in infants.

    Science.gov (United States)

    Hevroni, Avigdor; Goldman, Aliza; Blank-Brachfeld, Miriam; Abu Ahmad, Wiessam; Ben-Dov, Lior; Springer, Chaim

    2018-01-15

    To evaluate tidal breathing (TB) flow-volume and flow-time curves for identification of expiratory airway obstruction in infants. Pulmonary function tests were analyzed retrospectively in 156 infants aged 3-24 months with persistent or recurrent respiratory complaints. Parameters derived from TB curves were compared to maximal expiratory flow at functional residual capacity ([Formula: see text]maxFRC) measured by rapid thoracoabdominal compression technique. Analyzed parameters were: inspiratory time (t I ), expiratory time (t E ), tidal volume, peak tidal expiratory flow (PTEF), time to peak tidal expiratory flow (t PTEF ), expiratory flow when 50% and 25% of tidal volume remains in the lungs (FEF 50 , FEF 25 , respectively), and the ratios t PTEF /t E , t I /t E , FEF 50 /PTEF, and FEF 25 /PTEF. Statistical comparisons between flow indices and TB parameters were performed using mean squared error and Pearson's sample correlation coefficient. The study population was also divided into two groups based on severity of expiratory obstruction (above or below z-score for [Formula: see text]maxFRC of -2) to generate receiver operating characteristic (ROC) curves and calculate discriminatory values between the groups. TB parameters that were best correlated to [Formula: see text]maxFRC were: t PTEF /t E , FEF 50 /PTEF, and FEF 25 /PTEF, with r = 0.61, 0.67, 0.65, respectively (p < 0.0001 for all). ROC curves for FEF 50 /PTEF, FEF 25 /PTEF and t PTEF /t E showed areas under the curve of 0.813, 0.797, and 0.796, respectively. Cutoff value z-scores of -0.35, -0.34, and -0.43 for these three parameters, respectively, showed an 86% negative predictive value for severe airway obstructions. TB curves can assist in ruling out severe expiratory airway obstruction in infants.

  10. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.

    2017-03-10

    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.

  11. Relationship between regional ventilation and aerosol deposition in tidal breathing

    Energy Technology Data Exchange (ETDEWEB)

    Trajan, M.; Logus, J.W.; Enns, E.G.; Man, S.F.

    1984-07-01

    The regional distribution of the deposition of 1.2 micron particles of 99mTc sulfur colloid inhaled by tidal breathing was compared with the distribution of ventilation as measured by a 133Xe washout technique. Twelve subjects were studied, 6 with normal pulmonary function tests, 5 with air-flow limitation, and 1 with unilateral phrenic nerve paralysis. Both xenon and aerosol were inhaled at tidal volume by the subjects while seated upright. A large field gamma camera acquired posterior scans. Thirteen experiments were also done on 7 dogs: 1 with extrathoracic obstruction of the airway to 1 lung, and 12 with bronchoconstriction from the instillation of methacholine chloride into the airways of a lower lobe. Two of these dogs were studied with a gamma camera system, and the others were studied with a Picker multi-probe system. Both in humans and in dogs, an increase in time constant, which indicated a decrease in ventilation, was associated with an increase in peripheral aerosol deposition when normalized for ventilation. It is suggested that the increased residence time is responsible for the increased deposition in regions that received lesser ventilation.

  12. Relationship between regional ventilation and aerosol deposition in tidal breathing

    International Nuclear Information System (INIS)

    Trajan, M.; Logus, J.W.; Enns, E.G.; Man, S.F.

    1984-01-01

    The regional distribution of the deposition of 1.2 micron particles of 99mTc sulfur colloid inhaled by tidal breathing was compared with the distribution of ventilation as measured by a 133Xe washout technique. Twelve subjects were studied, 6 with normal pulmonary function tests, 5 with air-flow limitation, and 1 with unilateral phrenic nerve paralysis. Both xenon and aerosol were inhaled at tidal volume by the subjects while seated upright. A large field gamma camera acquired posterior scans. Thirteen experiments were also done on 7 dogs: 1 with extrathoracic obstruction of the airway to 1 lung, and 12 with bronchoconstriction from the instillation of methacholine chloride into the airways of a lower lobe. Two of these dogs were studied with a gamma camera system, and the others were studied with a Picker multi-probe system. Both in humans and in dogs, an increase in time constant, which indicated a decrease in ventilation, was associated with an increase in peripheral aerosol deposition when normalized for ventilation. It is suggested that the increased residence time is responsible for the increased deposition in regions that received lesser ventilation

  13. Tidal effects in twin-degenerate binaries

    International Nuclear Information System (INIS)

    Campbell, C.G.

    1984-01-01

    The tidal velocity field is calculated for an initially non-rotating low mass white dwarf secondary in a twin-degenerate binary. These motions are used to find the tidal torque on the secondary, to first order in the orbital frequency, and an expression is derived for the synchronization time. For a lobe-filling secondary the synchronization time has a weak dependence on the mass and luminosity of the star, and for the binary G61-29 is found to be of the same order as the estimated lifetime of the system. It is emphasized, however, that tidal excitation of non-radial oscillatory modes in the secondary may significantly shorten the synchronization time. (author)

  14. Tidal analysis of Met rocket wind data

    Science.gov (United States)

    Bedinger, J. F.; Constantinides, E.

    1976-01-01

    A method of analyzing Met Rocket wind data is described. Modern tidal theory and specialized analytical techniques were used to resolve specific tidal modes and prevailing components in observed wind data. A representation of the wind which is continuous in both space and time was formulated. Such a representation allows direct comparison with theory, allows the derivation of other quantities such as temperature and pressure which in turn may be compared with observed values, and allows the formation of a wind model which extends over a broader range of space and time. Significant diurnal tidal modes with wavelengths of 10 and 7 km were present in the data and were resolved by the analytical technique.

  15. The wave and tidal resource of Scotland

    Science.gov (United States)

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

    2017-04-01

    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.

  16. TIDAL TURBULENCE SPECTRA FROM A COMPLIANT MOORING

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-13

    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.

  17. Ocean energy. Tide and tidal power

    Energy Technology Data Exchange (ETDEWEB)

    Finkl, Charles W. [Coastal Planning and Engineering, Inc., Boca Raton, FL (United States); Charlier, Roger H.

    2009-07-01

    Engineers' dreams and fossil energy replacement schemes can come true. Man has been tapping the energy of the sea to provide power for his industries for centuries. Tidal energy combined with that of waves and marine winds rank among those most successfully put the work. Large scale plants are capital intensive but smaller ones, particularly built in China, have proven profitable. Since the initiation of the St Malo project in France, similar projects have gone into active service where methods have been devised to cut down on costs, new types of turbines developed and cost competitiveness considerably improved. Tidal power has enormous potential. The book reviews recent progress in extracting power from the ocean, surveys the history of tidal power harnessing and updates a prior publication by the author. (orig.)

  18. 40 CFR 35.926 - Value engineering (VE).

    Science.gov (United States)

    2010-07-01

    ... 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...

  19. From Globular Clusters to Tidal Dwarfs: Structure Formation in Tidal Tails

    Science.gov (United States)

    Knierman, K.; Hunsberger, S.; Gallagher, S.; Charlton, J.; Whitmore, B.; Hibbard, J.; Kundu, A.; Zaritsky, D.

    1999-12-01

    Galaxy interactions trigger star formation in tidal debris. How does this star formation depend on the local and global physical conditions? Using WFPC2/HST images, we investigate the range of structure within tidal tails of four classic ``Toomre Sequence'' mergers: NGC 4038/9 (``Antennae''), NGC 7252 (``Atoms for Peace''), NGC 3921, and NGC 3256. These tails contain a variety of stellar associations with sizes from globular clusters up to dwarf Irregulars. We explore whether there is a continuum between the two extremes. Our eight fields sample seven tidal tails at a variety of stages in the evolutionary sequence. Some of these tails are rich in HI while others are HI poor. Large tidal dwarfs are embedded in three of the tails. Using V and I WFPC2 images, we measure luminosities and colors of substructures within the tidal tails. The properties of globular cluster candidates in the tails will be contrasted with those of the hundreds of young clusters in the central regions of these mergers. We address whether globular clusters form and survive in the tidal tails and whether tidal dwarfs are composed of only young stars. By comparing the properties of structures in the tails of the four mergers with different ages, we examine systematic evolution of structure along the evolutionary sequence and as a function of HI content. We acknowledge support from NASA through STScI, and from NSF for an REU supplement for Karen Knierman.

  20. Homogeneous wave turbulence driven by tidal flows

    Science.gov (United States)

    Favier, B.; Le Reun, T.; Barker, A.; Le Bars, M.

    2017-12-01

    When a moon orbits around a planet, the rotation of the induced tidal bulge drives a homogeneous, periodic, large-scale flow. The combination of such an excitation with the rotating motion of the planet has been shown to drive parametric resonance of a pair of inertial waves in a mechanism called the elliptical instability. Geophysical fluid layers can also be stratified: this is the case for instance of the Earth's oceans and, as suggested by several studies, of the upper part of the Earth's liquid Outer Core. We thus investigate the stability of a rotating and stratified layer undergoing tidal distortion in the limit where either rotation or stratification is dominant. We show that the periodic tidal flow drives a parametric subharmonic resonance of inertial (resp. internal) waves in the rotating (resp. stratified) case. The instability saturates into a wave turbulence pervading the whole fluid layer. In such a state, the instability mechanism conveys the tidal energy from the large scale tidal flow to the resonant modes, which then feed a succession of triadic resonances also generating small spatial scales. In the rotating case, we observe a kinetic energy spectrum with a k-2 slope for which the Coriolis force is dominant at all spatial scales. In the stratified case, where the timescale separation is increased between the tidal excitation and the Brunt-Väisälä frequencies, the temporal spectrum decays with a ω-2 power law up to the cut-off frequency beyond which waves do not exist. This result is reminiscent of the Garrett and Munk spectrum measured in the oceans and theoretically described as a manifestation of internal wave turbulence. In addition to revealing an instability driving homogeneous turbulence in geophysical fluid layers, our approach is also an efficient numerical tool to investigate the possibly universal properties of wave turbulence in a geophysical context.

  1. Increased Tidal Dissipation Using Advanced Rheological Models: Implications for Io and Tidally Active Exoplanets

    Science.gov (United States)

    Renaud, Joe P.; Henning, Wade G.

    2018-04-01

    The advanced rheological models of Andrade and Sundberg & Cooper are compared to the traditional Maxwell model to understand how each affects the tidal dissipation of heat within rocky bodies. We find both Andrade and Sundberg–Cooper rheologies can produce at least 10× the tidal heating compared to a traditional Maxwell model for a warm (1400–1600 K) Io-like satellite. Sundberg–Cooper can cause even larger dissipation around a critical temperature and frequency. These models allow cooler planets to stay tidally active in the face of orbital perturbations—a condition we term “tidal resilience.” This has implications for the time evolution of tidally active worlds and the long-term equilibria they fall into. For instance, if Io’s interior is better modeled by the Andrade or Sundberg–Cooper rheologies, the number of possible resonance-forming scenarios that still produce a hot, modern Io is expanded, and these scenarios do not require an early formation of the Laplace resonance. The two primary empirical parameters that define the Andrade anelasticity are examined in several phase spaces to provide guidance on how their uncertainties impact tidal outcomes, as laboratory studies continue to constrain their real values. We provide detailed reference tables on the fully general equations required for others to insert the models of Andrade and Sundberg–Cooper into standard tidal formulae. Lastly, we show that advanced rheologies can greatly impact the heating of short-period exoplanets and exomoons, while the properties of tidal resilience could mean a greater number of tidally active worlds among all extrasolar systems.

  2. Short period tidal variations of earth rotation

    Science.gov (United States)

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

    1981-01-01

    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.

  3. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline

    2015-01-01

    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.

  4. 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)

    2017-06-15

    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.)

  5. CLIMATE INSTABILITY ON TIDALLY LOCKED EXOPLANETS

    International Nuclear Information System (INIS)

    Kite, Edwin S.; Manga, Michael; Gaidos, Eric

    2011-01-01

    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 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 gases. Both

  6. CLIMATE INSTABILITY ON TIDALLY LOCKED EXOPLANETS

    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: edwin.kite@gmail.com [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2011-12-10

    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

  7. Mapping the Tidal Destruction of the Hercules Dwarf: A Wide-field DECam Imaging Search for RR Lyrae Stars

    Science.gov (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

    2018-01-01

    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.

  8. NOAA Historical Tidal Current Data for the Coastal United States

    Data.gov (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...

  9. 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...

  10. 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...

  11. Lagoon Sediment Dynamics: A Coupled Model to Study a Medium-Term Silting of Tidal Channels

    Directory of Open Access Journals (Sweden)

    Marco Petti

    2018-04-01

    Full Text Available The silting of tidal channels is a natural process that affects several shallow lagoons and makes it difficult to navigate, requiring regular maintenance interventions. This phenomenon is the result of the complex non-linear interaction between tidal currents and wave motion. In this work, the morphodynamic evolution of the Marano and Grado lagoon is investigated by means of a two-dimensional horizontal (2DH morphological-hydrodynamic and a spectral coupled model. An innovative procedure to reproduce the overall bathymetric changes in the medium term and, in particular, the volumes deposited inside channels, is presented. An average year with a sequence of winds and tides acting over that time was reconstructed, carrying out cross correlation techniques and spectral analyses of measured data. The predicted morphological evolution matches the annual dredged volumes in the lagoon critical branches and shows the distribution of erosion and deposition of cohesive sediments according to spatially variable values of critical shear stress.

  12. 2nd Workshop on Tidal Friction and the Earth's Rotation

    CERN Document Server

    Sündermann, Jürgen

    1982-01-01

    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 ...

  13. Gıdalar ve Mikrobiyolojik Riskler I

    Directory of Open Access Journals (Sweden)

    Velittin Gürgün

    2015-02-01

    Full Text Available Enfeksiyona neden olan ve toksijenik mikroorganizmalarla bulaşan gıdaların tüketilmesi sonucu görülen hastalıklar, acı çekmenin ve ölümlerin en önemli nedenlerinden biridir (Alen ve Kaferstein, 1983. Afrika ve Latin Amerika ile Çin dışındaki Asya ülkelerindeki 5 yaşın altındaki çocuklarda, yılda bir milyarın üzerinde gastroenterik vakaların görüldüğü ve kontamine gıdaların tüketilmesi nedeni ile de bu çocuklardan en az beş milyonunun öldüğü tahmin edilmektedir (Kaferstien ve Sims, 1987. Meksika ve Tayland gibi ülkelerde 0-4 yaş grubun çocukların, en az yarısının Campylobacter’in neden olduğu bağırsak enfeksiyonuna yakalandıkları sanılmaktadır. Avrupa’da ise gıdalardan kaynaklanan hastalıklar, solunum hastalıklarından sonra ikinci sırada yer almakta olup, bir çok Avrupa ülkesinde akut gastro-enteritis hastalığının yılda bir milyon kişiden ellibininde görüldüğü, hatta Hollanda’da bu oranın üçyüzbin olduğu tespit edilmiş bulunmaktadır (Guiguet vd. 1992; Notermans ve Van Der Giessen, 1993. Amerika Birleşik Devletleri için yürütülen tahminlerin bu sayıların da üstünde olduğu ve her yıl ABD’de bir milyon kişiden üçyüzellibin kişinin akut gastroenterik hastalıklara uğradıkları ve bunun da ağırlıklı olarak kontamine gıdalardan kaynaklandığı varsayılmaktadır (Archer ve Kvenberg, 1985. Her ne kadar gelişmiş ülkelerde görülen gıda kaynaklı hastalıklar gelişmekte olan ülkelerdekine göre oldukça düşükse de, sıkça kronikleşerek romatizmal hastalıklar (ankylosing spondylitis ve Reiter’s sendromu beslenme ve emilim bozukluğu problemleri, hemolotik-üremik sendromlar (Escherichia coli’nin özellikle 0157: H7 serotipinin ürettiği verotoksinden dolayı, damar sertliği (atherosclerosis ve Campylobacter türlerinin enfeksiyonunu takiben görülen Guillain-Barre sendromu sonucunu doğurmaktadır (Archer, 1984, 1987; Archer ve

  14. Tidal propagation off the central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    . [Keywords: Tidal propagation, Mumbai high, Global tidal model, Shelf model, Central west coast of India] Introduction In coastal regions, tides play an important role in determining circulation and hydrography. Barotropic tides coming from the open... with increase in the width of the shelf. Materials and Methods Global tidal models Schwiderski5 used a hydrodynamic interpolation technique to determine the amplitude and phase of tidal constituents of global ocean. Since the availability of satellite...

  15. Morphodynamics of the Manyema Tidal Delta at Kunduchi, Tanzania

    African Journals Online (AJOL)

    Keywords: Morphodynamics, Kunduchi, Manyema, shoreline change, tidal creek, tidal delta. Abstract—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 ... Western Indian Ocean J. Mar. Sci. Vol. 11, No. 2, pp.

  16. Field migration rates of tidal meanders recapitulate fluvial morphodynamics

    Science.gov (United States)

    Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

    2018-02-01

    The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

  17. How Tidal Forces Cause Ocean Tides in the Equilibrium Theory

    Science.gov (United States)

    Ng, Chiu-king

    2015-01-01

    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.

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

    African Journals Online (AJOL)

    The tidal exchange of larvae of the salt-marsh grapsid crab Sesarma catenata was studied in the Swartkops estuary, a tidally driven, shallow estuary in Algoa Bay, South Africa. Plankton samples were collected bimonlhly during spring and neap tides from October to March at the tidal inlet. Samples were collected hourly for ...

  19. Tidal Marshes: The Boundary between Land and Ocean.

    Science.gov (United States)

    Gosselink, James

    An overview of the ecology of the tidal marshes along the gulf coast of the United States is presented. The following topics are included: (1) the human impact on tidal marshes; (2) the geologic origins of tidal marshes; (3) a description of the physical characteristics and ecosystem of the marshlands; (4) a description of the marshland food chain…

  20. Field migration rates of tidal meanders recapitulate fluvial morphodynamics.

    Science.gov (United States)

    Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

    2018-02-13

    The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths. Copyright © 2018 the Author(s). Published by PNAS.

  1. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (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...

  2. Empirical Tidal Dissipation in Exoplanet Hosts From Tidal Spin-up

    Science.gov (United States)

    Penev, Kaloyan; Bouma, L. G.; Winn, Joshua N.; Hartman, Joel D.

    2018-04-01

    Stars with hot Jupiters (HJs) tend to rotate faster than other stars of the same age and mass. This trend has been attributed to tidal interactions between the star and planet. A constraint on the dissipation parameter {Q}\\star {\\prime } follows from the assumption that tides have managed to spin up the star to the observed rate within the age of the system. This technique was applied previously to HATS-18 and WASP-19. Here, we analyze the sample of all 188 known HJs with an orbital period tidal dissipation parameter ({Q}\\star {\\prime }) increases sharply with forcing frequency, from 105 at 0.5 day‑1 to 107 at 2 day‑1. This helps to resolve a number of apparent discrepancies between studies of tidal dissipation in binary stars, HJs, and warm Jupiters. It may also allow for a HJ to damp the obliquity of its host star prior to being destroyed by tidal decay.

  3. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

    Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'

  4. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

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

    2000-01-01

    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

  5. Estuaries and Tidal Marshes. Habitat Pac.

    Science.gov (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…

  6. Life on the Tidal Mudflats: Elkhorn Slough.

    Science.gov (United States)

    Andresen, Ruth

    Life in an estuarine environment is studied in this set of audio-visual materials prepared for grades 6-12. A 71-frame colored filmstrip, cassette tape narration, and teacher's guide focus upon Elkhorn Slough, a tidal mudflat in the Monterey Bay area, California. Topics examined range from river drainage and the effects of pollution on living…

  7. An optimal tuning strategy for tidal turbines

    Science.gov (United States)

    2016-01-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This ‘impatient-tuning strategy’ results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing ‘patient-tuning strategy’ which maximizes the power output averaged over the tidal cycle. This paper presents a ‘smart patient tuning strategy’, which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine’s average power output. PMID:27956870

  8. Palaemon pacijicus (Stimpson) in eastern Cape tidal

    African Journals Online (AJOL)

    1984-09-25

    Sep 25, 1984 ... seasonally with peak numbers and biomass found in summer ... One part of the programme dealt with the tidal pool ... pools sampled. Unicam spectrophotometer at 458 run. A dilution series was made for each batch of concentrate used. A domestic water meter was coupled to the outlet of a portable pump ...

  9. An optimal tuning strategy for tidal turbines.

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This 'impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing 'patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a 'smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  10. Nova Scotia Power : in-stream tidal

    International Nuclear Information System (INIS)

    Meade, K.

    2007-01-01

    The Government of Nova Scotia, the Government of New Brunswick, Nova Scotia Power and others have funded a feasibility study of North American sites for commercial instream tidal power. In July 2007, Nova Scotia Power received partial funding for a demonstration project. This presentation provided information on a demonstration plant for tidal power run by Nova Scotia Power. It discussed the benefits of the Open Hydro technology for this plant. In this simple design, the generator is on the circumference of the turbine. The design does not involve any power transmission systems or any pitching of blades. In addition, the technology is environmentally sound as it is completely shrouded, has low rotational speed, and a large open centre allows fish to pass through, and it does not require lubricants. The last benefit that was presented was the scale up of 250 kW machine deployed in a European test facility. The presentation also discussed the advantages of developing tidal power at this time. It was concluded that tidal energy has significant potential. Although it is intermittent, it is predictable and bulk power system can be scheduled to accommodate it. figs

  11. The history of tidal power in France

    International Nuclear Information System (INIS)

    Banal, M.

    1997-01-01

    The first known use of tidal power in France concerns the tidal mills in general use during the Middle Age along the French coasts. The first research studies of tidal power plants started at the end of the first world war but it is only in 1940 with the stimulus of Robert Gibrat that was created the Research Society for the use of Tides and the Rance plant project. In 1946, Electricite de France (EdF) started again the studies of this company for a greater size project in the Chausey archipelago which was abandoned for the benefit of the Rance project in the 1960's. The start up of the plant took place in 1967 but the other projects were abandoned during the 1980's. This short paper recalls the historical aspects of the development of tidal power in France and focusses on the research and development studies and on the economical, political and legal factors that led to retain the Rance project among others proposed. (J.S.)

  12. Carbon sequestration by Australian tidal marshes

    KAUST Repository

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

    2017-01-01

    ) 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

  13. Phase lag control of tidally reversing mega-ripple geometry and bed stress in tidal inlets

    Science.gov (United States)

    Traykovski, P.

    2016-02-01

    Recent observations in the Columbia River Mouth, New River Inlet, and Wasque Shoals have shown that tidally reversing mega-ripples are an ubiquitous bedform morphology in energetic tidal inlets. As the name implies, these bedforms reverse asymmetry and migration direction in each half tidal cycle. With wavelengths of 2 to 5 m and heights of 0.2 to 0.5 m, these bedforms are larger than current formed ripples, but smaller than dunes. Unlike dunes which have a depth dependent geometry, observations indicate the tidally reversing mega-ripples geometry is related to the time dependent tidal flow and independent of depth. Previous empirical relations for predicting the geometry of ripples or dunes do not successfully predict the geometry of these features. A time dependent geometric model was developed that accounts for the reversal of migration and asymmetry to successfully predict bedform geometry. The model requires sufficient sediment transport in each half tidal cycle to reverse the asymmetry before the bedforms begin to grow. Both the observations and model indicate that the complete reversal of asymmetry and development of a steep lee face occurs near or after maximum flow in each half tidal cycle. This phase lag in bedform response to tidal forcing also has important implications for bed stress in tidal inlets. Observations of frictional drag in the Columbia River mouth based on a tidal momentum balance of surface slope over 10 km regressed against quadratic near bed velocity show drag coefficients that fall off as CD U-1.4. Reynolds stress measurements performed using the dual ADV differencing technique show similar relations. The Reynolds stress measurements also show a dramatic asymmetry between accelerating flows and decelerating flows with a factor of 5 increase during deceleration. Pulse coherent Doppler profiles of near bed turbulence indicate that the turbulence is dominated by energetic fluctuations in separation zones downstream of steep lee faces. The

  14. TIDAL EVOLUTION OF CLOSE-IN PLANETS

    International Nuclear Information System (INIS)

    Matsumura, Soko; Rasio, Frederic A.; Peale, Stanton J.

    2010-01-01

    Recent discoveries of several transiting planets with clearly non-zero eccentricities and some large obliquities started changing the simple picture of close-in planets having circular and well-aligned orbits. The two major scenarios that form such close-in planets are planet migration in a disk and planet-planet interactions combined with tidal dissipation. The former scenario can naturally produce a circular and low-obliquity orbit, while the latter implicitly assumes an initially highly eccentric and possibly high-obliquity orbit, which are then circularized and aligned via tidal dissipation. Most of these close-in planets experience orbital decay all the way to the Roche limit as previous studies showed. We investigate the tidal evolution of transiting planets on eccentric orbits, and find that there are two characteristic evolution paths for them, depending on the relative efficiency of tidal dissipation inside the star and the planet. Our study shows that each of these paths may correspond to migration and scattering scenarios. We further point out that the current observations may be consistent with the scattering scenario, where the circularization of an initially eccentric orbit occurs before the orbital decay primarily due to tidal dissipation in the planet, while the alignment of the stellar spin and orbit normal occurs on a similar timescale to the orbital decay largely due to dissipation in the star. We also find that even when the stellar spin-orbit misalignment is observed to be small at present, some systems could have had a highly misaligned orbit in the past, if their evolution is dominated by tidal dissipation in the star. Finally, we also re-examine the recent claim by Levrard et al. that all orbital and spin parameters, including eccentricity and stellar obliquity, evolve on a similar timescale to orbital decay. This counterintuitive result turns out to have been caused by a typo in their numerical code. Solving the correct set of tidal

  15. Relativistic tidal properties of neutron stars

    International Nuclear Information System (INIS)

    Damour, Thibault; Nagar, Alessandro

    2009-01-01

    We study the various linear responses of neutron stars to external relativistic tidal fields. We focus on three different tidal responses, associated to three different tidal coefficients: (i) a gravito-electric-type coefficient Gμ l =[length] 2l+1 measuring the lth-order mass multipolar moment GM a 1 ...a l induced in a star by an external lth-order gravito-electric tidal field G a 1 ...a l ; (ii) a gravito-magnetic-type coefficient Gσ l =[length] 2l+1 measuring the lth spin multipole moment GS a 1 ...a l induced in a star by an external lth-order gravito-magnetic tidal field H a 1 ...a l ; and (iii) a dimensionless 'shape' Love number h l measuring the distortion of the shape of the surface of a star by an external lth-order gravito-electric tidal field. All the dimensionless tidal coefficients Gμ l /R 2l+1 , Gσ l /R 2l+1 , and h l (where R is the radius of the star) are found to have a strong sensitivity to the value of the star's 'compactness'c≡GM/(c 0 2 R) (where we indicate by c 0 the speed of light). In particular, Gμ l /R 2l+1 ∼k l is found to strongly decrease, as c increases, down to a zero value as c is formally extended to the 'black hole (BH) limit'c BH =1/2. The shape Love number h l is also found to significantly decrease as c increases, though it does not vanish in the formal limit c→c BH , but is rather found to agree with the recently determined shape Love numbers of black holes. The formal vanishing of μ l and σ l as c→c BH is a consequence of the no-hair properties of black holes. This vanishing suggests, but in no way proves, that the effective action describing the gravitational interactions of black holes may not need to be augmented by nonminimal worldline couplings.

  16. Role of bronchodilation and pattern of breathing in increasing tidal expiratory flow with progressive induced hypercapnia in chronic obstructive pulmonary disease.

    Science.gov (United States)

    Finucane, Kevin E; Singh, Bhajan

    2018-01-01

    Hypercapnia (HC) in vitro relaxes airway smooth muscle; in vivo, it increases respiratory effort, tidal expiratory flows (V̇ exp ), and, by decreasing inspiratory duration (Ti), increases elastic recoil pressure (Pel) via lung viscoelasticity; however, its effect on airway resistance is uncertain. We examined the contributions of bronchodilation, Ti, and expiratory effort to increasing V̇ exp with progressive HC in 10 subjects with chronic obstructive pulmonary disease (COPD): mean forced expiratory volume in 1 s (FEV 1 ) 53% predicted. Lung volumes (Vl), V̇ exp , esophageal pressure (Pes), Ti, and end-tidal Pco 2 ([Formula: see text]) were measured during six tidal breaths followed by an inspiratory capacity (IC), breathing air, and at three levels of HC. V̇ exp and V̇ with submaximal forced vital capacities breathing air (V̇ sFVC ) were compared. Pulmonary resistance ( Rl) was measured from the Pes-V̇ relationship. V̇ exp and Pes at end-expiratory lung volume (EELV) + 0.3 tidal volume [V̇ (0.3Vt) and Pes (0.3Vt) , respectively], Ti, and Rl correlated with [Formula: see text] ( P pulmonary disease (COPD), progressive HC increases tidal expiratory flows by inducing bronchodilation and via an increased rate of inspiration and lung viscoelasticity, a probable increase in lung elastic recoil pressure, both changes increasing expiratory flows, promoting lung emptying and a stable end-expiratory volume. Bronchodilation with HC occurred despite optimal standard bronchodilator therapy, suggesting that in COPD further bronchodilation is possible.

  17. Light rays and the tidal gravitational pendulum

    Science.gov (United States)

    Farley, A. N. St J.

    2018-05-01

    Null geodesic deviation in classical general relativity is expressed in terms of a scalar function, defined as the invariant magnitude of the connecting vector between neighbouring light rays in a null geodesic congruence projected onto a two-dimensional screen space orthogonal to the rays, where λ is an affine parameter along the rays. We demonstrate that η satisfies a harmonic oscillator-like equation with a λ-dependent frequency, which comprises terms accounting for local matter affecting the congruence and tidal gravitational effects from distant matter or gravitational waves passing through the congruence, represented by the amplitude, of a complex Weyl driving term. Oscillating solutions for η imply the presence of conjugate or focal points along the rays. A polarisation angle, is introduced comprising the orientation of the connecting vector on the screen space and the phase, of the Weyl driving term. Interpreting β as the polarisation of a gravitational wave encountering the light rays, we consider linearly polarised waves in the first instance. A highly non-linear, second-order ordinary differential equation, (the tidal pendulum equation), is then derived, so-called due to its analogy with the equation describing a non-linear, variable-length pendulum oscillating under gravity. The variable pendulum length is represented by the connecting vector magnitude, whilst the acceleration due to gravity in the familiar pendulum formulation is effectively replaced by . A tidal torque interpretation is also developed, where the torque is expressed as a coupling between the moment of inertia of the pendulum and the tidal gravitational field. Precessional effects are briefly discussed. A solution to the tidal pendulum equation in terms of familiar gravitational lensing variables is presented. The potential emergence of chaos in general relativity is discussed in the context of circularly, elliptically or randomly polarised gravitational waves encountering the null

  18. Environmental consequences of tidal power in a hyper-tidal muddy regime: the Severn estuary

    International Nuclear Information System (INIS)

    Kirby, R.

    1997-01-01

    Muddy hyper-tidal regimes, such as the Severn Estuary in the UK, are especially difficult for plants and animals. The difficulties stem from the semi-diurnal and semi-lunar energy fluctuations. On spring tides entrained fine sediment induces elevated suspended sediment concentrations such that photosynthesis is inhibited. On neap tides much of the entrained fine sediment is deposited on the sub-tidal bed over periods of several days to form ephemeral dense layers, which reach in excess of 100 G/l and rapidly become anaerobic on stagnation. Such occasional bed faunas as develop are characterised by very large numbers of immature individuals of a few species. One of the few organisms able to cope with the extreme conditions is the siliceous reef-building worn Sabellaria. Arising from the long term suppression in its calcareous fauna, erosion and winnowing of these Holocene clays fails to give rise to lag shell deposits, called chenier ridges, found elsewhere in eroding muddy inter-tidal systems. A tidal power barrage would shift the regime from hyper-tidal to macro-tidal decrease in turbidity would permit photosynthesis and phytoplankton growth, so stimulating the higher food chain. Ironically, perhaps, cleaning up the sewage discharges in the estuary, in the absence of barrage construction would lead to a wading bird crash whereas barrage construction would lead to an improved carrying capacity. (author)

  19. 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.

    2005-01-01

    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

  20. Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP

    Science.gov (United States)

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

    2017-09-01

    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.

  1. Tidal regimes and salt marshes - the River Hamble analogue

    International Nuclear Information System (INIS)

    Gray, A.J.; Moy, I.L.; Warman, E.A.; Dawson, F.H.; Henville, P.

    1993-01-01

    Construction of estuarine tidal-energy barrages has a potentially major effect on the tidal regime of the estuary, particularly upstream of a barrage. Because tidal regime largely controls the distribution and species composition of intertidal plant and animal communities, it is important to understand how barrages may affect such communities. The main objectives of the research described in this report were to relate recent changes in tidal regime within an embanked area of salt marsh and mudflat to changes in the distribution of plant species. This was to test predictions about tidal control of species' range and to assess the site's suitability as an analogue of post-barrage conditions. (author)

  2. Functional Analysis of the Tomato Immune Receptor Ve1 through Domain Swaps with Its Non-Functional Homolog Ve2

    Science.gov (United States)

    Rovenich, Hanna; Song, Yin; Liebrand, Thomas W. H.; Masini, Laura; van den Berg, Grardy C. M.; Joosten, Matthieu H. A. J.; Thomma, Bart P. H. J.

    2014-01-01

    Resistance in tomato against race 1 strains of the fungal vascular wilt pathogens Verticillium dahliae and V. albo-atrum is mediated by the Ve locus. This locus comprises two closely linked inversely oriented genes, Ve1 and Ve2, which encode cell surface receptors of the extracellular leucine-rich repeat receptor-like protein (eLRR-RLP) type. While Ve1 mediates Verticillium resistance through monitoring the presence of the recently identified V. dahliae Ave1 effector, no functionality for Ve2 has been demonstrated in tomato. Ve1 and Ve2 contain 37 eLRRs and share 84% amino acid identity, facilitating investigation of Ve protein functionality through domain swapping. In this study it is shown that Ve chimeras in which the first thirty eLRRs of Ve1 were replaced by those of Ve2 remain able to induce HR and activate Verticillium resistance, and that deletion of these thirty eLRRs from Ve1 resulted in loss of functionality. Also the region between eLRR30 and eLRR35 is required for Ve1-mediated resistance, and cannot be replaced by the region between eLRR30 and eLRR35 of Ve2. We furthermore show that the cytoplasmic tail of Ve1 is required for functionality, as truncation of this tail results in loss of functionality. Moreover, the C-terminus of Ve2 fails to activate immune signaling as chimeras containing the C-terminus of Ve2 do not provide Verticillium resistance. Furthermore, Ve1 was found to interact through its C-terminus with the eLRR-containing receptor-like kinase (eLRR-RLK) interactor SOBIR1 that was recently identified as an interactor of eLRR-RLP (immune) receptors. Intriguingly, also Ve2 was found to interact with SOBIR1. PMID:24505431

  3. Tidal disruption of fuzzy dark matter subhalo cores

    Science.gov (United States)

    Du, Xiaolong; Schwabe, Bodo; Niemeyer, Jens C.; Bürger, David

    2018-03-01

    We study tidal stripping of fuzzy dark matter (FDM) subhalo cores using simulations of the Schrödinger-Poisson equations and analyze the dynamics of tidal disruption, highlighting the differences with standard cold dark matter. Mass loss outside of the tidal radius forces the core to relax into a less compact configuration, lowering the tidal radius. As the characteristic radius of a solitonic core scales inversely with its mass, tidal stripping results in a runaway effect and rapid tidal disruption of the core once its central density drops below 4.5 times the average density of the host within the orbital radius. Additionally, we find that the core is deformed into a tidally locked ellipsoid with increasing eccentricities until it is completely disrupted. Using the core mass loss rate, we compute the minimum mass of cores that can survive several orbits for different FDM particle masses and compare it with observed masses of satellite galaxies in the Milky Way.

  4. Tidal Friction in the Earth and Ocean

    Science.gov (United States)

    Ray, R. D.

    2006-12-01

    "Tidal Friction" is a classic subject in geophysics, with ties to some of the great scientists of the Victorian era. The subject has been reinvigorated over the past decade by space geodesy, and particularly by the Topex/Poseidon satellite altimeter mission. In fact, the topic has now taken on some significance in oceanography, with potential implications for problems of mixing, thermocline maintenance, and the thermohaline circulation. Likewise, tidal measurements have become sufficiently precise to reveal new information about the solid earth. In this respect, the tidal force is an invaluable "probe" of the earth, at frequencies well outside the seismic band. This talk will "follow the energy" of tides while noting some important geophysical implications at each stage. In the present earth-moon-sun configuration, energy for tides is extracted from the earth's rotation. Ancient eclipses bear witness to this, and the discrepancy between Babylonian (and other) observations and tidal predictions yields unique information about the mantle and the overlying fluid envelope. Complementary information comes from tidal anelasticity estimates, which are now available at frequencies ranging from semidiurnal to fortnightly, monthly, and 18.6 years. These data, when combined with various kinds of gravity measurements, are relevant to the present-day sea-level problem. Solid-earth tidal dissipation represents less than 5% of the system total. As has long been realized, the largest energy sink is the ocean. About 70% of the oceanic dissipation occurs in shallow seas (the traditional sink) and 30% in the deep ocean, generally near rugged bottom topography. The latter represents a substantial amount of power, roughly 1 gigawatt, available for generation of internal tides and other baroclinic motions. Experiments like HOME are helping unravel the links between barotropic tides, internal tides, turbulence, and mixing. The latter opens possible linkages to climate, and recent work

  5. Tidal power dams in the Bay of Fundy

    International Nuclear Information System (INIS)

    Walsun, W. van

    1998-01-01

    The challenges of harnessing tidal power and the construction of dams and tidal power plants in a tidal-ocean environment such as the Bay of Fundy in New Brunswick are discussed. In the 1966-1988 series of studies, three sites were chosen at the Bay of Fundy as being the most promising, namely (1) site B9 in Minas Basin at the entrance to Cobequid Bay, (2) site A8 at the narrow neck beyond the entrance to Cumberland Basin, and (3) site A6 at the entrance to Shepody Bay. All the sites are located at the head of the Bay of Fundy because that is where the maximum tidal ranges are found and a basin's tidal energy potential is proportional to the square of its tidal range. Site B9 was determined to have the greatest tidal power potential but no plant has ever been built because reports have stated that a solid conventional tidal power barrage at site B9 would increase the tidal range at Boston by as much as 30 cm. Rather than abandoning the site for this reason, an installation consisting of a series of piers from shore to shore with hydraulic turbines mounted in the spaces between piers, was suggested. A simple mathematical model has been developed for determining the operation of this tidal fence. The cost of energy, generated by the tidal fence at site B9 was also calculated. Further studies are suggested to determine the exact environmental effect of the tidal fence on the tidal regime. If environmental problems persist, machines with larger discharge capabilities could be considered to reduce the interference of the fence with natural tidal movements. 9 refs., 6 figs

  6. Hamilelik ve periodontal hastalık

    OpenAIRE

    Sağlam, Ebru; Saruhan, Nesrin; Çanakçı, Cenk Fatih

    2015-01-01

    Hamileliğe bağlı olarak annede görülen bazı immünolojik değişiklikler enfeksiyonlara yatkınlığı artırmaktadır. Periodontal hastalık, başlıca sebebi mikrobiyal dental plak olan, multifaktöriyel ve çeşitli şiddetlerde görülen yaygın bir hastalıktır. Periodontal hastalığın klinik olarak birçok tanı kriteri bulunmaktadır. Hamilelik ve periodontal enflamasyon arasındaki ilişki uzun yıllardır bilinmektedir. Periodontal hastalık, hamilelerde sistemik durumu etkilemektedir ve fetusa da olumsuz etkile...

  7. Yaşam Bilimleri ve Biyoteknoloji

    Directory of Open Access Journals (Sweden)

    Rasime DEMİREL

    2010-10-01

    Full Text Available Eskişehir (Türkiye’deki farklı marketlerden toplanmış olan şişelenmiş doğal ve mineral suların mikrobiyal kalitesi incelenmiştir. Membran filtrasyon tekniği uygulanarak su örneklerinin kalitesi; toplam koliform, Escherichia coli, Enterococcus spp., Aeromonas hydrophila’nın varlığı ve miktarı yönünden analiz edilmiştir. Aerobik bakteriler 22 ve 37 ºC’de inkübasyonu sonucunda ml’deki heterotrofik bakteri sayısı (HPC olarak belirlenmiştir. Şişelenmiş mineral su örneklerinde Bacillus türleri belirlenirken, şişelenmiş içme suyu örneklerinde herhangi bir bakteri ya da kontaminasyon bulunmamıştır

  8. Melatonin ve Klinik Önemi

    OpenAIRE

    Fehmi, Özgüner; Özcankaya, Ramazan; Delibaş, Namık; Koyu, Ahmet; Çalışkan, Sadettin

    2009-01-01

    SüleymanDemirel Üniversitesi TIP FAKÜLTESİ DERGİSİ: 1995 Aralık; 2(4) Melatonin ve Klinik Önemi Fehmi Özgüner Ramazan Özcankaya Namık Delibaş Ahmet Koyu Sadettin Çalışkan . Özet Melatonin karanlık periyotta sentezlenir ve salınır, ayrıca karanlığın süresi hakkındaki bilginin değerlendirilmesine aracılık eder. Melatonin sirkadiyan ritmi, gençlerde oldukça düzenlidir, yaşlılıkta sıklıkla siklus bozulma gösterir ve bir hipomelatoninemi sendromu ola...

  9. Probiyotik Mayalar ve Özellikleri

    Directory of Open Access Journals (Sweden)

    Hatice Yıldıran

    2017-10-01

    Full Text Available Probiyotikler tüketicinin sağlığı üzerinde olumlu etkileri olan mikroorganizmalardır. Probiyotik uygulamalarının sağlık üzerine etkileri hakkında yapılmış pekçok araştırma bulunmaktadır. En yaygın kullanılan probiyotik bakteriler; bifidobakteriler ve laktobasiller, laktokoklar ve streptokoklar gibi laktik asit bakterileridir. İnsanlar için probiyotik olarak kullanılan mikroorganizmalar arasında ayrıca mayalar, basiller ve enterokoklar da bulunmaktadır. Probiyotik mayalar son yıllarda bilim insanları için ilgi çekici bir alan olmuştur. Yapılan bazı çalışmalar Saccharomyces cinsine ait türlerin antibakteriyel ve probiyotik özelliklere sahip olabileceklerini göstermiştir. Saccharomyces boulardii yıllardır insanları farklı gastrointestinal rahatsızlıklarından korumak veya hastalıklardan iyileştirmek amacıyla probiyotik olarak kullanılan, patojenik olmayan bir mayadır. S. boulardii özellikle ilaç endüstrisinde genellikle liyofilize formda kullanılmaktadır. Yapılan bu derleme çalışmasında probiyotikler, mayaların probiyotik olma özellikleri ve probiyotik mayaların kullanım alanları hakkında bilgiler verilmiş ve bu alanda yapılan araştırmalardan örnekler sunulmuştur.

  10. Using VE to Strategically Plan Our Future

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-01

    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.

  11. Van Otlu Peynirinin Yapılışı ve Mikrobiyolojik, Fiziksel ve Kimyasal Nitelikleri

    Directory of Open Access Journals (Sweden)

    Ahmet Kurt

    2015-02-01

    Full Text Available Bu araştırmada 10 adet taze Van Otlu peyniri örneklerine; mikrobiyolojik, fiziksel ve kimyasal analizler uygulanmıştır. Peynir teknolojisinde, sağlık, teknik ve ekonomik yönden önemli olan toplam koliform, süt asidi, lipolitik ve proteolitik mikroorganizmalarla maya ve küflerin sayısal değerleri yanında rutubet, yağ, yağsız kurumadde, kurumaddede yağ, protein, suda eriyen protein, kül, tuz, saf kül, kurumaddede tuz ve % asitlik oranları, peynir örneklerinde ayrı ayrı saptanmıştır. Elde edilen sonuçlara göre peynir yapımı çok dağınık ve ilkel karakter arz etmektedir. Peynirlerin yapımındaki farklı uygulamalar, teknik bilgi ve yöntem noksanlığı yüzünden, gerek mikrobiyolojik analiz ve gerekse fiziksel ve kimyasal analiz sonuçları örnekten örneğe önemli fraklılıklar göstermiştir. Peynir örneklerinde saptanan Koliform organizma sayıları, hem sağlık yönünden hem de peynirlerin olgunlaşmalarında sorunlara neden olabilecek düzeydedir.

  12. Experiments on topographies lacking tidal conversion

    Science.gov (United States)

    Maas, Leo; Paci, Alexandre; Yuan, Bing

    2015-11-01

    In a stratified sea, internal tides are supposedly generated when the tide passes over irregular topography. It has been shown that for any given frequency in the internal wave band there are an infinite number of exceptions to this rule of thumb. This ``stealth-like'' property of the topography is due to a subtle annihilation of the internal waves generated during the surface tide's passage over the irregular bottom. We here demonstrate this in a lab-experiment. However, for any such topography, subsequently changing the surface tide's frequency does lead to tidal conversion. The upshot of this is that a tidal wave passing over an irregular bottom is for a substantial part trapped to this irregularity, and only partly converted into freely propagating internal tides. Financially supported by the European Community's 7th Framework Programme HYDRALAB IV.

  13. 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)

    2016-06-01

    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.

  14. Tidal Disruption Events from Eccentric Nuclear Disks

    Science.gov (United States)

    Wernke, Heather N.; Madigan, Ann-Marie

    2018-04-01

    Stars that get too close to a supermassive black hole are in danger of being tidally disrupted. Stellar two-body relaxation is commonly assumed to be the main driver of these events. Recent work has shown, however, that secular gravitational torques from eccentric nuclear disks can push stars to extreme eccentricities at much higher rates than predicted by two-body relaxation. This work did not include the effects of general relativity, however, which could quench secular torques via rapid apsidal precession. Here we show that, for a star in danger of disruption, general relativity acts on a timescale of less than an orbital period. This short timescale means that general relativity does not have enough time to have a major effect on the orbit. When driven by secular torques from eccentric nuclear disks, tidal disruption event rates are not affected by general relativity.

  15. The influence of neap-spring tidal variation and wave energy on sediment flux in salt marsh tidal creeks

    Science.gov (United States)

    Lacy, Jessica; Ferner, Matthew C.; Callaway, John C.

    2018-01-01

    Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three six-to-ten-week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally-averaged suspended-sediment flux (SSF) in the tidal creeks decreased with increasing tidal energy, and SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF measured during the deployments. During ebb tides following the highest tides, velocities exceeded 1 m/s in the narrow tidal creeks, resulting in negative tidally-averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally-averaged SSF was positive in wavey conditions with moderate tides. Spring-tide sediment export was about 50% less at a station 130 m further up the tidal creek than at the creek mouth. The negative tidally-averaged water flux near the creek mouth during spring tides indicates that in the lower marsh, some of the water flooding directly across the bay--marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well.

  16. Integrating tidal and nontidal ecological assessments

    Science.gov (United States)

    Mark Southerland; Roberto Llanso

    2016-01-01

    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 ...

  17. The commercial prospects for tidal stream power

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The prospects for obtaining energy from tidal currents were examined in 1993 when it was concluded that, although the UK resource is large, the unit cost of energy would be relatively high. Interest has continued, however, and in December 2000 the Energy Technology Support Unit (ETSU), on behalf of the Department of Trade and Industry (DTI), commissioned Binnie Black and Veatch (BBV) to re-examine these prospects from a commercial point of view. (author)

  18. Effect of tidal fields on star clusters

    Science.gov (United States)

    Chernoff, David; Weinberg, Martin

    1991-01-01

    We follow the dynamical evolution of a star cluster in a galactic tidal field using a restricted N-body code. We find large asymmetric distortions in the outer profile of the cluster in the first 10 or so crossing times as material is lost. Prograde stars escape preferentially and establish a potentially observable retrograde rotation in the halo. We present the rate of particle loss and compare with the prescription proposed by Lee and Ostriker (1987).

  19. Tidal power from the River Mersey

    International Nuclear Information System (INIS)

    1991-01-01

    The studies described in this report relate to work carried out since those reported upon in the stage I Mersey Barrage Report on the possible construction of a tidal power barrage on the Mersey Estuary. The objectives of the work were to review basic engineering, re-assess cost and energy output, improve engineering configuration, quantify social, industrial and regional effects, determine preferred alignment, review the main environmental impacts, assess economic viability and financing and identify further study requirements. (UK)

  20. Tidal controls on river delta morphology

    Science.gov (United States)

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

    2017-09-01

    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. Tidally Driven Failure Along Europa's Rhadamanthys Linea

    Science.gov (United States)

    Cameron, M.; Konter, B.; Pappalardo, R. T.

    2013-12-01

    The surface of Europa is crosscut by a dense network of fractures and there are many candidate faults for studying past tectonic activity. To better understand the role of tidal stress sources and implications for faulting on Europa, we investigate the relationship between shear and normal stresses at Rhadamanthys Linea, a northwest oriented fracture in the northern hemisphere. Previous work on Agenor Linea, a right-lateral strike-slip fracture in the southern hemisphere, suggests that both tidal diurnal and non-synchronous rotation (NSR) stresses play a critical role in the mechanics of Coulomb shear failure on Europa. At Agenor Linea, shear failure from diurnal tidal stress mechanisms is difficult to achieve because the relatively large over¬burden stress (ie., 1.2 MPa at 1 km depth) dominates the stress field; however, MPa order stresses from NSR permit right-lateral shear failure along the west side of the fault at shallow depths (Astypalea Linea and Conamara Chaos will also be investigated, offering a unique comparison of geologic activity of fractures residing in geographically diverse locations of Europa.

  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

    2016-10-01

    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. Tidal controls on earthquake size-frequency statistics

    Science.gov (United States)

    Ide, S.; Yabe, S.; Tanaka, Y.

    2016-12-01

    The possibility that tidal stresses can trigger earthquakes is a long-standing issue in seismology. Except in some special cases, a causal relationship between seismicity and the phase of tidal stress has been rejected on the basis of studies using many small events. However, recently discovered deep tectonic tremors are highly sensitive to tidal stress levels, with the relationship being governed by a nonlinear law according to which the tremor rate increases exponentially with increasing stress; thus, slow deformation (and the probability of earthquakes) may be enhanced during periods of large tidal stress. Here, we show the influence of tidal stress on seismicity by calculating histories of tidal shear stress during the 2-week period before earthquakes. Very large earthquakes tend to occur near the time of maximum tidal stress, but this tendency is not obvious for small earthquakes. Rather, we found that tidal stress controls the earthquake size-frequency statistics; i.e., the fraction of large events increases (i.e. the b-value of the Gutenberg-Richter relation decreases) as the tidal shear stress increases. This correlation is apparent in data from the global catalog and in relatively homogeneous regional catalogues of earthquakes in Japan. The relationship is also reasonable, considering the well-known relationship between stress and the b-value. Our findings indicate that the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal stress levels. This finding has clear implications for probabilistic earthquake forecasting.

  4. Tidally influenced alongshore circulation at an inlet-adjacent shoreline

    Science.gov (United States)

    Hansen, Jeff E.; Elias, Edwin P.L.; List, Jeffrey H.; Erikson, Li H.; Barnard, Patrick L.

    2013-01-01

    The contribution of tidal forcing to alongshore circulation inside the surfzone is investigated at a 7 km long sandy beach adjacent to a large tidal inlet. Ocean Beach in San Francisco, CA (USA) is onshore of a ∼150 km2 ebb-tidal delta and directly south of the Golden Gate, the sole entrance to San Francisco Bay. Using a coupled flow-wave numerical model, we find that the tides modulate, and in some cases can reverse the direction of, surfzone alongshore flows through two separate mechanisms. First, tidal flow through the inlet results in a barotropic tidal pressure gradient that, when integrated across the surfzone, represents an important contribution to the surfzone alongshore force balance. Even during energetic wave conditions, the tidal pressure gradient can account for more than 30% of the total alongshore pressure gradient (wave and tidal components) and up to 55% during small waves. The wave driven component of the alongshore pressure gradient results from alongshore wave height and corresponding setup gradients induced by refraction over the ebb-tidal delta. Second, wave refraction patterns over the inner shelf are tidally modulated as a result of both tidal water depth changes and strong tidal flows (∼1 m/s), with the effect from currents being larger. These tidally induced changes in wave refraction result in corresponding variability of the alongshore radiation stress and pressure gradients within the surfzone. Our results indicate that tidal contributions to the surfzone force balance can be significant and important in determining the direction and magnitude of alongshore flow.

  5. Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

    Science.gov (United States)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. Here 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. The model derived from more than 12 years of satellite data reveals an Approximately 72 km thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

  6. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2015-12-01

    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.

  7. Yaşam Bilimleri ve Biyoteknoloji

    Directory of Open Access Journals (Sweden)

    Kazım UYSAL

    2011-02-01

    Full Text Available Yoğun zirai faaliyetlerin yapıldığı Antalya’nın batı sahillerinden yakalanan ekonomik önemi olan bazı deniz balıklarının (Diplodus sargus, Siganus rivulatus, Lithognathus mormyrus, Liza aurata, Chelon labrasus kas, deri ve solungaçlarındaki bakır, çinko, mangan, demir ve magnezyum (Genellikle zirai aktivitelerden kaynaklanırlar biyoakümülasyon seviyeleri araştırılmıştır. Balıkların dokularında incelenen elementlerin minimum ve maksimum seviyeleri (mg kg-1 yaş ağırlık bakır için 0.541.69; çinko için 4.14-407.23; mangan için 0.15-9.17; demir için 3.45-104.49 ve magnezyum için 204.33- 784.30 olarak tespit edilmiştir. İncelenen elementlerin en düşük biyoakümülasyon seviyeleri kas dokularda, en yüksek seviyeler (Bakır hariç ise solungaçlarda tespit edilmiştir. İncelenen türlerin kas dokularındaki bakır ve çinko seviyeleri (Dünya Sağlık Örgütü (WHO, Gıda ve Tarım Örgütü (FAO ve Türk Gıda Kodeksi’nde belirtilen kabul edilebilir maksimum seviyelerden daha düşük, bazı türlerin (D. sargus, S. rivulatus, L. mormyrus and L. aurata derilerinde bulunan çinko seviyeleri ise kabul edilebilir maksimum seviyelerden daha yüksek bulunmuştur

  8. From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies

    Science.gov (United States)

    Knierman, Karen A.; Gallagher, Sarah C.; Charlton, Jane C.; Hunsberger, Sally D.; Whitmore, Bradley; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis

    2003-09-01

    Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic ``Toomre sequence'' mergers: NGC 4038/39 (``Antennae''), NGC 3256, NGC 3921, and NGC 7252 (``Atoms for Peace'') have been studied in order to explore how the star formation depends on the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence and tails with and without embedded tidal dwarf galaxies. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of blue clusters (0.2<~V-I<~0.9), particularly in its western tail, similar to those found in the inner region of the merger. In contrast, NGC 4038/39 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters along their tails. A significant cluster population is clearly associated with the prominent tidal dwarf candidates in the eastern and western tails of NGC 7252. The cluster-rich western tail of NGC 3256 is not distinguished from the others by its dynamical age or by its total H I mass. However, the mergers that have few clusters in the tail all have tidal dwarf galaxies, while NGC 3256 does not have prominent tidal dwarfs. We speculate that star formation in tidal tails may manifest itself either in small structures like clusters along the tail or in large structures such as dwarf galaxies, but not in both. Also, NGC 3256 has the highest star formation rate of the four mergers studied, which may contribute to the high number of star clusters in its tidal tails. Based in part on observations obtained with the

  9. Tidal effects on groundwater contamination at Pekan, Pahang

    International Nuclear Information System (INIS)

    Nor Dalila Desa; Dominic, J.A.; Mohd Muzamil Mohd Hashim; Kamarudin Samuding; Mohd Faizun Khalid; Mod Omar Hassan; Kamaruzaman Mohamad

    2014-01-01

    The meeting of coastal ground water and the sea is a unique and dynamic hydro geologic boundary phenomenon that has fascinated groundwater engineers and scientists for the past century. The variation of seawater level resulting from tidal fluctuations is usually neglected in regional groundwater flow studies. In this study the effects of seawater tidal on groundwater are investigated using geophysical together with conventional method. Comparative result between these two methods shown how tidal fluctuations effects groundwater in study area. (author)

  10. Excess Molar Volume of Binary Mixtures of Methylheptenone+Alkanols at 298.15 K

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Excess molar volume(VE) data on binary liquid mixtures of methylheptenone (MHO) with methanol, ethanol, n-propanol or n-butanol have been determined from the density measurements at 298.15 K and atmospheric pressure. The values of VE in all the systems over the entire composition range are quantified by the Redlich-Kister equation. The effects of the chain length of alkanols on VE are discussed.

  11. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing.

    Science.gov (United States)

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

    2015-11-15

    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 (R(2) ≈ 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 < 0.05). 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. Copyright © 2015 the American Physiological Society.

  12. Tidal sails : an alternative to turbines for harvesting tidal current energy

    Energy Technology Data Exchange (ETDEWEB)

    Hanssen, J.E. [Tidal Sails, Haugesund (Norway)

    2008-07-01

    Tidal sail technology harnesses the energy of tidal streams in order to produce electricity. Tidal currents move the sails that are attached to wires that rotate generator wheels to produce electricity. The technology has a low impact on the surrounding environment and is simple to install. This presentation discussed the methods used to determine the influence of relative sail velocity and measure estimated energy output levels. The sails were recently tested at an on-grid tidal stream pilot in the Norwegian Arctic. A 300 kW turbine installed at the site demonstrated that the site was suitable for a full-scale development of 20 tripod-mounted 600 kW turbines placed at 50 m depth. It was estimated that the 10 strings of 1000 m length provided between 200 and 250 GWh per year. The sails have also been used at a high speed site in Washington state in the United States. The 25 m pilot plant was installed to verify site suitability and examine sail behaviour in real, high-flow currents. It is expected that the technology will be fully commercialized by 2011. Other pilot tests are being conducted to examine flow behaviour; mooring and flotation functionality; and launch and lift capabilities. Engineering work is ongoing to examine plant designs, variable sail spacing, and collaborations with key component suppliers. tabs., figs.

  13. 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.

    2016-01-01

    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

  14. Atmospheric dynamics of tidally synchronized extrasolar planets.

    Science.gov (United States)

    Cho, James Y-K

    2008-12-13

    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.

  15. Physics and observations of tidal disruption events

    Science.gov (United States)

    Mangalam, Arun; Mageshwaran, Tamilan

    2018-04-01

    We describe a model of tidal disruption events (TDEs) with input physical parameters that include the black hole (BH) mass M•, the specific orbital energy E, the angular momentum J, the star mass M⊙ and radius R⊙. We calculate the rise time of the TDEs, the peak bolometric luminosity in terms of these physical parameters and a typical light curve of TDEs for various All Sky Survey (ASS) and Deep Sky Survey (DSS) missions. We then derive the expected detection rates and discuss the follow up of TDEs through observations in various spectral bands from X-rays to radio wavelengths.

  16. Comprehensive Characterization a Tidal Energy Site (Invited)

    Science.gov (United States)

    Polagye, B. L.; Thomson, J. M.; Bassett, C. S.; Epler, J.; Northwest National Marine Renewable Energy Center

    2010-12-01

    Northern Admiralty Inlet, Puget Sound, Washington is the proposed location of a pilot tidal energy project. Site-specific characterization of the physical and biological environment is required for device engineering and environmental analysis. However, the deep water and strong currents which make the site attractive for tidal energy development also pose unique challenges to collecting comprehensive information. This talk focuses on efforts to optimally site hydrokinetic turbines and estimate their acoustic impact, based on 18 months of field data collected to date. Additional characterization efforts being undertaken by the University of Washington branch of the Northwest National Marine Renewable Energy Center and its partners include marine mammal presence and behavior, water quality, seabed geology, and biofouling potential. Because kinetic power density varies with the cube of horizontal current velocity, an accurate map of spatial current variations is required to optimally site hydrokinetic turbines. Acoustic Doppler profilers deployed on the seabed show operationally meaningful variations in flow characteristics (e.g., power density, directionality, vertical shear) and tidal harmonic constituents over length scales of less than 100m. This is, in part, attributed to the proximity of this site to a headland. Because of these variations, interpolation between stationary measurement locations introduces potentially high uncertainty. The use of shipboard acoustic Doppler profilers is shown to be an effective tool for mapping peak currents and, combined with information from seabed profilers, may be able to resolve power density variations in the project area. Because noise levels from operating turbines are expected to exceed regulatory thresholds for incidental harassment of marine mammals known to be present in the project area, an estimate of the acoustic footprint is required to permit the pilot project. This requires site-specific descriptions of pre

  17. Tidal Wetlands and Coastal Ocean Carbon Dynamics

    Science.gov (United States)

    Hopkinson, C.; Wang, S. R.; Forbrich, I.; Giblin, A. E.; Cai, W. J.

    2017-12-01

    Recent overviews of coastal ocean C dynamics have tidal wetlands in a prominent position: a local sink for atmospheric CO2, a local store of OC, and a source of DIC and OC for the adjacent estuary and nearshore ocean. Over the past decade there have been great strides made in quantifying and understanding these flows and linkages. GPP and R of the wetlands are not nearly as imbalanced as thought 30 yrs ago. Heterotrophy of adjacent estuarine waters is not solely due to the respiration of OC exported from the marsh, rather we see the marsh directly respiring into the water during tidal inundation and accumulated marsh DIC draining into tidal creeks. Organic carbon burial on the marsh is still a relatively minor flux, but it is large relative to marsh NEE. Using literature and unpublished data on marsh DIC export, we used examples from Sapelo Island GA USA and Plum Island MA USA to constrain estimates of NEP and potential OC export. P. There remain large uncertainties in quantifying C dynamics of coupled wetland - estuary systems. Gas exchange from the water to atmosphere is one of the largest uncertainties. Work at Sapelo suggests that upwards of 40% of all daily exchange occurs from water flooding the marsh, which is but a few hours a day. This estimate is based on the intercept value for gas exchange vs wind velocity. Another major uncertainty comes from converting between O2 based estimates of metabolism to C. At Sapelo we find PQ and RQ values diverging greatly from Redfield. Finally, C dynamics of the coastal ocean, especially the role of tidal wetlands is likely to change substantially in the future. Studies at Plum Island show a reversal of the 4000 yr process of marsh progradation with marshes eroding away at their edges because of inadequate sediment supply and rising sea level. The fate of eroded OC is questionable. Landward transgression with SLR is the only likely counter to continued wetland loss - but that's a complex social issue requiring new

  18. Sensitivity of growth characteristics of tidal sand ridges and long bed waves to formulations of bed shear stress, sand transport and tidal forcing : A numerical model study

    NARCIS (Netherlands)

    Yuan, Bing; de Swart, Huib E.; Panadès, Carles

    2016-01-01

    Tidal sand ridges and long bed waves are large-scale bedforms that are observed on continental shelves. They differ in their wavelength and in their orientation with respect to the principal direction of tidal currents. Previous studies indicate that tidal sand ridges appear in areas where tidal

  19. Conditions for tidal bore formation in convergent alluvial estuaries

    Science.gov (United States)

    Bonneton, Philippe; Filippini, Andrea Gilberto; Arpaia, Luca; Bonneton, Natalie; Ricchiuto, Mario

    2016-04-01

    Over the last decade there has been an increasing interest in tidal bore dynamics. However most studies have been focused on small-scale bore processes. The present paper describes the first quantitative study, at the estuary scale, of the conditions for tidal bore formation in convergent alluvial estuaries. When freshwater discharge and large-scale spatial variations of the estuary water depth can be neglected, tide propagation in such estuaries is controlled by three main dimensionless parameters: the nonlinearity parameter ε0 , the convergence ratio δ0 and the friction parameter ϕ0. In this paper we explore this dimensionless parameter space, in terms of tidal bore occurrence, from a database of 21 estuaries (8 tidal-bore estuaries and 13 non tidal-bore estuaries). The field data point out that tidal bores occur for convergence ratios close to the critical convergence δc. A new proposed definition of the friction parameter highlights a clear separation on the parameter plane (ϕ0,ε0) between tidal-bore estuaries and non tidal-bore estuaries. More specifically, we have established that tidal bores occur in convergent estuaries when the nonlinearity parameter is greater than a critical value, εc , which is an increasing function of the friction parameter ϕ0. This result has been confirmed by numerical simulations of the two-dimensional Saint Venant equations. The real-estuary observations and the numerical simulations also show that, contrary to what is generally assumed, tide amplification is not a necessary condition for tidal bore formation. The effect of freshwater discharge on tidal bore occurrence has been analyzed from the database acquired during three long-term campaigns carried out on the Gironde/Garonne estuary. We have shown that in the upper estuary the tidal bore intensity is mainly governed by the local dimensionless tide amplitude ε. The bore intensity is an increasing function of ε and this relationship does not depend on freshwater

  20. The origin of neap-spring tidal cycles

    Science.gov (United States)

    Kvale, E.P.

    2006-01-01

    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.

  1. Classification of tidal inlets along the Central east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.A.; Vikas, M.; Rao, S.; JayaKumar S.

    ) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo...

  2. The Nature of VeLLOs

    Science.gov (United States)

    Huard, Tracy L.; Pound, Marc W.; Mundy, Lee; Dunham, Michael

    2018-01-01

    Very Low Luminosity Objects (VeLLOs) are young stellar sources that are defined by luminosities less than 0.1 solar luminosity and rising mid-infrared spectral energy distributions. But, what exactly are they? Brown dwarfs or low-mass stars in formation? Systems exhibiting low accretion rates? Extremely young objects? We have completed an ALMA survey of 33 candidates in the nearby Serpens, Ophiuchus, and Lupus star-forming molecular clouds. Continuum emission at 1.3 mm, consistent with the presence of an inner envelope and/or disk, was detected toward 17 candidates, with at least 6 of these candidates exhibiting CO outflow emission, suggesting ongoing formation. We will present these observations and results, and discuss their implications concerning the nature of VeLLOs.

  3. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2016-04-01

    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

  4. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak İçindekiler

    2016-08-01

    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

  5. Yaşam Bilimleri ve Biyoteknoloji

    Directory of Open Access Journals (Sweden)

    Nalan YILMAZ SARIÖZLÜ

    2010-10-01

    Full Text Available Eskişehir/Türkiye’deki ılıca sularındaki bakteriyel topluluğun ortaya konulması ve incelenmesi için 7 ılıca su örneği 7 farklı ılıcadan toplanmıştır. Tüm örnekler dört farklı besi ortamına (nutrient agar, su-maya ekstraktı agar, triptik soy agar, nişasta-kazein agar inoküle edilmiştir. 50 °C’de 14 günlük inkübasyondan sonra tüm bakteri kolonilerinin sayımı yapılıp saflaştırılmıştır. Tüm izolatların gram reaksiyonları, katalaz veoksidazözellikleri belirlenmişve BIOLOG, VITEK veotomatikribotiplendirme sisteminde (RiboPrinter incelenmişlerdir. Bu bakterilerin ampisilin, gentamisin, trimetoprim-sülfametoksazol ve tetrasiklin antibiyotiklerine karşı dirençliliği incelenmiştir. Sonuç olarak normal insan florasına ilaveten ısıya dirençli patojenik mikroorganizmalar incelenen alandaki ılıca sularında (43-50 °C belirlenmiştir. Altı genusa ait 10 farklı tür Alysiella filiformis, Bordetella bronchiseptica, B. pertussis, Molexalla caprae, M. caviae, M. cuniculi, M. phenylpyruvica, Roseomonas fauriae, Delftia acidovorans ve Pseudomonas taetrolens olarak tanımlanmıştır

  6. Tidal constraints on the interior of Venus

    Science.gov (United States)

    Dumoulin, C.; Tobie, G.; Verhoeven, O.; Rosenblatt, P.; Rambaux, N.

    2017-12-01

    As a prospective study for a future exploration of Venus, we compute the tidal response of Venus' interior assuming various mantle compositions and temperature profiles representative of different scenarios of Venus' formation and evolution. The mantle density and seismic velocities are modeled from thermodynamical equilibria of mantle minerals and used to predict the moment of inertia, Love numbers, and tide-induced phase lag characterizing the signature of the internal structure in the gravity field. The viscoelasticity of the mantle is parameterized using an Andrade rheology. From the models considered here, the moment of inertia lies in the range of 0.327 to 0.342, corresponding to a core radius of 2900 to 3450 km. Viscoelasticity of the mantle strongly increases the potential Love number relative to previously published elastic models. Due to the anelasticity effects, we show that the possibility of a completely solid metal core inside Venus cannot be ruled out based on the available estimate of k2 from the Magellan mission (Konopliv and Yoder, 1996). A Love number k2 lower than 0.27 would indicate the presence of a fully solid iron core, while for larger values, solutions with an entirely or partially liquid core are possible. Precise determination of the Love numbers, k2 and h2, together with an estimate of the tidal phase lag, are required to determine the state and size of the core, as well as the composition and viscosity of the mantle.

  7. Time scales in tidal disruption events

    Directory of Open Access Journals (Sweden)

    Krolik J.

    2012-12-01

    Full Text Available We explore the temporal structure of tidal disruption events pointing out the corresponding transitions in the lightcurves of the thermal accretion disk and of the jet emerging from such events. The hydrodynamic time scale of the disrupted star is the minimal time scale of building up the accretion disk and the jet and it sets a limit on the rise time. This suggest that Swift J1644+57, that shows several flares with a rise time as short as a few hundred seconds could not have arisen from a tidal disruption of a main sequence star whose hydrodynamic time is a few hours. The disrupted object must have been a white dwarf. A second important time scale is the Eddington time in which the accretion rate changes form super to sub Eddington. It is possible that such a transition was observed in the light curve of Swift J2058+05. If correct this provides interesting constraints on the parameters of the system.

  8. Tidal instability in exoplanetary systems evolution

    Directory of Open Access Journals (Sweden)

    Le Gal P.

    2011-02-01

    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.

  9. Tidal conversion by a knife-edge

    Science.gov (United States)

    Llewellyn Smith, S. G.; Young, W. R.

    2003-04-01

    We obtain an analytic solution for the generation of internal gravity waves by tidal flow past a vertical barrier of height b in a uniformly stratified ocean of depth h>b and buoyancy frequency N. If b/h is small and N is constant, the radiated power (watts per metre of barrier) is (pi/4) ρ_0 b^2 U^2 N sqrt{1-(f/ω)^2} where ρ_0 is the mean density of seawater, U \\cos (ω t) the incident tidal velocity, and f the Coriolis frequency. The radiated power increases rapidly with b/h; as b/h to 1 the radiated power diverges as ln[(h-b)/b]. By solving an integral equation numerically, we calculate the conversion in a realistically stratified ocean in which the buoyancy frequency increases by a factor of fifty between the abyss and the thermocline. The radiated power is greater by a factor of about three than that of a uniformly stratified ocean with N equal to the vertically averaged buoyancy frequency.

  10. Tidal Dwarf Galaxies and Missing Baryons

    Directory of Open Access Journals (Sweden)

    Frederic Bournaud

    2010-01-01

    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”.

  11. Angular momentum transport by tidal acoustic wave

    International Nuclear Information System (INIS)

    Sakurai, T.

    1976-01-01

    An analytical expression of the braking torque on a Jacobian ellipsoid rotating steadily in an enviromental gas is given, based on the assumption that the ellipsoid rotates around its shortest principal axis with an angular momentum slightly larger than that at the bifurcation point of the Maclaurin spheroid. This braking torque is effected by the gravitational interaction between the ellipsoid matter and a spiral density configuration in the environmental gas. This spiral configuration which is called a tidal acoustic wave, is caused by the zone of silence effect in a supersonic flow. With respect to a coordinates system rotating with the ellipsoid, a supersonic region appears outside a certain radius. In this supersonic region, the effect of the non-axisymmetric fluctuation in the ellipsoid potential propagates along the downstream branches of the Mach waves. This one-sided response of the supersonic part causes the tidal acoustic wave. The discussion is restricted to the equatorial plane, and an acoustic approximation of the basic equations is used under the assumption that the self-gravity effect of the environmental gas is negligable in comparison to the main gravity of the ellipsoid. The results are applied to the pre- and post-Main sequence phases of a rotating star, and relating astrophysical problems are discussed. (Auth.)

  12. Angular momentum transport by tidal acoustic wave

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, T [Kyoto Univ. (Japan). Faculty of Engineering

    1976-05-01

    An analytical expression of the braking torque on a Jacobian ellipsoid rotating steadily in an enviromental gas is given, based on the assumption that the ellipsoid rotates around its shortest principal axis with an angular momentum slightly larger than that at the bifurcation point of the Maclaurin spheroid. This braking torque is effected by the gravitational interaction between the ellipsoid matter and a spiral density configuration in the environmental gas. This spiral configuration which is called a tidal acoustic wave, is caused by the zone of silence effect in a supersonic flow. With respect to a coordinates system rotating with the ellipsoid, a supersonic region appears outside a certain radius. In this supersonic region, the effect of the non-axisymmetric fluctuation in the ellipsoid potential propagates along the downstream branches of the Mach waves. This one-sided response of the supersonic part causes the tidal acoustic wave. The discussion is restricted to the equatorial plane, and an acoustic approximation of the basic equations is used under the assumption that the self-gravity effect of the environmental gas is negligable in comparison to the main gravity of the ellipsoid. The results are applied to the pre- and post-Main sequence phases of a rotating star, and relating astrophysical problems are discussed.

  13. Davras Dagı (Isparta ve Çevresinin Orman ve Çalı Vejetasyonu

    Directory of Open Access Journals (Sweden)

    Coşkun SAĞLAM

    2009-04-01

    Full Text Available Bu vejetasyon çalısması, 2002-2005 yılları arasında Batı Toroslar'da yer alan Davras Dagı ve çevresinde gerçeklestirildi. Vejetasyon Braun-Blanquet (1964 metoduna göre analiz edilerek orman ve çalı vejetasyonuna ait yedi birlik tespit edildi. Bunlardan bes tanesi yenidir. Orman vejetasyonu: Sınıf : Quercetea pubescentis (Oberd, 1948 Doing Kraft, 1955 Ordo : Querco – Cedretalia libani Barbéro, Loisel ve Quézel, 1974 1. Minuartio globulosi – Juniperetum excelsae ass. nova 2. Sileno squamigeri – Quercetum cerridis ass. nova 3. Astragalo oxytropifolii – Pinetum caramanicae ass. nova Alyans : Lonicero nummulariaefoliae – Cedrion libani Quézel, Barbéro ve Akman 1978 4. Veronico syriaci – Cedretum libani ass. nova 5. Diantho cibrarii – Quercetum vulcanicae Kurt et al. 1996 Sınıf : Quercetea ilicis Br.-Bl., 1947 Ordo : Quercetalia ilicis Br.-Bl., 1947, Rivaz Martinez, 1974 Alyans : Quercion cocciferae Quézel, Barbéro, Akman, 1978 6. Hyperico polyphylli – Pinetum brutiae ass. nova Çalı Vejetasyonu: Sınıf : Quercetea pubescentis (Oberd, 1948 Doing Kraft, 1955 Ordo : Querco – Cedretalia libani Barbéro, Loisel ve Quézel, 1974 7. Astragalo atropurpureus– Quercetum cocciferae Kargıoglu, 19

  14. Rapid evolution of a marsh tidal creek network in response to sea level rise.

    Science.gov (United States)

    Hughes, Z. J.; Fitzgerald, D. M.; Mahadevan, A.; Wilson, C. A.; Pennings, S. C.

    2008-12-01

    In the Santee River Delta (SRD), South Carolina, tidal creeks are extending rapidly onto the marsh platform. A time-series of aerial photographs establishes that these channels were initiated in the 1950's and are headward eroding at a rate of 1.9 m /yr. Short-term trends in sea level show an average relative sea level rise (RSLR) of 4.6 mm/yr over a 20-year tide gauge record from nearby Winyah Bay and Charleston Harbor (1975-1995). Longer-term (85-year) records in Charleston suggest a rate of 3.2 mm/yr. RSLR in the SRD is likely even higher as sediment cores reveal that the marsh is predominantly composed of fine-grained sediment, making it highly susceptible to compaction and subsidence. Furthermore, loss in elevation will have been exacerbated by the decrease in sediment supply due to the damming of the Santee River in 1939. The rapid rate of headward erosion indicates that the marsh platform is in disequilibrium; unable to keep pace with RSLR through accretionary processes and responding to an increased volume and frequency of inundation through the extension of the drainage network. The observed tidal creeks show no sinuosity and a distinctive morphology associated with their young age and biological mediation during their evolution. Feedbacks between tidal flow, vegetation and infauna play a strong role in the morphological development of the creeks. The creek heads are characterized by a region denuded of vegetation, the edges of which are densely populated and burrowed by Uca Pugnax (fiddler crab). Crab burrowing destabilizes sediment, destroys rooting and impacts drainage. Measured infiltration rates are three orders of magnitude higher in the burrowed regions than in a control area (1000 ml/min and 0.6 ml/min respectively). Infiltration of oxygenated water enhances decomposition of organic matter and root biomass is reduced within the creek head (marsh=4.3 kg/m3, head=0.6 kg/m3). These processes lead to the removal and collapse of the soils, producing

  15. Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

    Directory of Open Access Journals (Sweden)

    Brian G. Sellar

    2018-01-01

    Full Text Available The data analyses and results presented here are based on the field measurement campaign of the Reliable Data Acquisition Platform for Tidal (ReDAPT project (Energy Technologies Institute (ETI, U.K. 2010–2015. During ReDAPT, a 1 MW commercial prototype tidal turbine was deployed and operated at the Fall of Warness tidal test site within the European Marine Energy Centre (EMEC, Orkney, U.K. Mean flow speeds and Turbulence Intensity (TI at multiple positions proximal to the machine are considered. Through the implemented wave identification techniques, the dataset can be filtered into conditions where the effects of waves are present or absent. Due to the volume of results, only flow conditions in the absence of waves are reported here. The analysis shows that TI and mean flows are found to vary considerably between flood and ebb tides whilst exhibiting sensitivity to the tidal phase and to the specification of spatial averaging and velocity binning. The principal measurement technique was acoustic Doppler profiling provided by seabed-mounted Diverging-beam Acoustic Doppler Profilers (D-ADP together with remotely-operable Single-Beam Acoustic Doppler Profilers (SB-ADP installed at mid-depth on the tidal turbine. This novel configuration allows inter-instrument comparisons, which were conducted. Turbulence intensity averaged over the rotor extents of the ReDAPT turbine for flood tides vary between 16.7% at flow speeds above 0.3 m/s and 11.7% when considering only flow speeds in the turbine operating speed range, which reduces to 10.9% (6.8% relative reduction following the implementation of noise correction techniques. Equivalent values for ebb tides are 14.7%, 10.1% and 9.3% (7.9% relative reduction. For flood and ebb tides, TI values resulting from noise correction are reduced in absolute terms by 3% and 2% respectively across a wide velocity range and approximately 1% for turbine operating speeds. Through comparison with SB-ADP-derived mid

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

    Directory of Open Access Journals (Sweden)

    Alice Bravin

    2016-02-01

    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.

  17. Morphodynamics of the Manyema tidal delta 1 LIST OF TABLES ...

    African Journals Online (AJOL)

    Kheira Kortenbout

    Morphodynamics of the Manyema tidal delta. 1. LIST OF ... Location of Manyema Creek and its associated tidal delta platform at Kunduchi. Fig. 2. ... platform. Beachcomber. Hotel. Whitesands. Hotel. Kunduchi. Beach Hotel. Giraffe. Hotel. INDIAN. OCEAN. Mombasa. Dar es. Salaam. KUNDUCHI. KENYA. TANZANIA.

  18. Anomaly Detection Techniques for the Condition Monitoring of Tidal Turbines

    Science.gov (United States)

    2014-09-29

    turbine design includes many horizontal and vertical axis solutions, some with major structural and operational variations (Aly & El-Hawary, 2011...However, a common focus is the horizontal axis design, holding many similarities with a standard wind turbine . Maintenance on tidal turbines ...However, despite similarities between tidal and wind power turbine design, the operating environment is vastly different. Water is over 800 times

  19. Tidal bending of glaciers: a linear viscoelastic approach

    DEFF Research Database (Denmark)

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

    2003-01-01

    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...

  20. Flow and sediment transport in an Indonesian tidal network

    NARCIS (Netherlands)

    Buschman, F.A.

    2011-01-01

    The Berau river, situated in east Kalimantan (Indonesia), drains a relatively small catchment area and splits into several interconnected tidal channels. This tidal network connects to the sea. The sea is host to extremely diverse coral reef communities. Also the land side of the region is

  1. Water and suspended sediment division at a stratified tidal junction

    NARCIS (Netherlands)

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

    2013-01-01

    [1] Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper

  2. Water and suspended sediment division at a stratified tidal junction

    NARCIS (Netherlands)

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

    2013-01-01

    Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper

  3. 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 method of unsupervised classification for Landsat-TM images, the tidal flats were identified, and the resulting areas ...

  4. 33 CFR 117.181 - Oakland Inner Harbor Tidal Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Oakland Inner Harbor Tidal Canal. 117.181 Section 117.181 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... Tidal Canal. The draws of the Alameda County highway drawbridges at Park Street, mile 5.2; Fruitvale...

  5. Relation between tidal damping and wave celerity in estuaries

    NARCIS (Netherlands)

    Savenije, H.H.G.; Veling, E.J.M.

    2005-01-01

    Observations in estuaries indicate that an amplified tidal wave moves considerably faster than is indicated by the classical equation for wave propagation. Similarly, the celerity of propagation is lower if the tidal wave is damped. This phenomenon is clearly observed in the Schelde estuary (located

  6. Potential sites for tidal power in New Jersey.

    Science.gov (United States)

    2014-04-01

    High-resolution simulation is made to model tidal energy along the coastlines of New Jersey (NJ) and its neighbor states with an : unprecedentedly fine grid. On the basis of the simulation, a thorough search is made for sites for tidal power generati...

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

    DEFF Research Database (Denmark)

    Gribsholt, B.; Andersson, M.; Boschker, H.T.S.

    2006-01-01

    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-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh...

  8. Tidal power - a major prospect for the 21st century

    International Nuclear Information System (INIS)

    Haws, E.T.

    1997-01-01

    Tidal power technology is reviewed and its prospects for the next century assessed. It is concluded that the technology is now in place and, given the political will to secure financing, tidal power offers a clean, renewable and sustainable source of power for the near future. (UK)

  9. Wave and tidal generation devices reliability and availability

    CERN Document Server

    Tavner, Peter John

    2017-01-01

    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.

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

    NARCIS (Netherlands)

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

    2013-01-01

    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

  11. Land Use in Korean Tidal Wetlands: Impacts and Management Strategies

    Science.gov (United States)

    Hong, Sun-Kee; Koh, Chul-Hwan; Harris, Richard R.; Kim, Jae-Eun; Lee, Jeom-Sook; Ihm, Byung-Sun

    2010-05-01

    The coastal landscapes in southwestern Korea include a diverse array of tidal wetlands and salt marshes. These coastal zones link the ecological functions of marine tidal wetlands and freshwater ecosystems with terrestrial ecosystems. They are rich in biological diversity and play important roles in sustaining ecological health and processing environmental pollutants. Korean tidal wetlands are particularly important as nurseries for economically important fishes and habitats for migratory birds. Diking, draining, tourism, and conversion to agricultural and urban uses have adversely affected Korean tidal wetlands. Recent large development projects have contributed to further losses. Environmental impact assessments conducted for projects affecting tidal wetlands and their surrounding landscapes should be customized for application to these special settings. Adequate environmental impact assessments will include classification of hydrogeomorphic units and consideration of their responses to biological and environmental stressors. As is true worldwide, Korean laws and regulations are changing to be more favorable to the conservation and protection of tidal wetlands. More public education needs to be done at the local level to build support for tidal wetland conservation. Some key public education points include the role of tidal wetlands in maintaining healthy fish populations and reducing impacts of nonpoint source pollution. There is also a need to develop procedures for integrating economic and environmental objectives within the overall context of sustainable management and land uses.

  12. Are Wave and Tidal Energy Plants New Green Technologies?

    Science.gov (United States)

    Douziech, Mélanie; Hellweg, Stefanie; Verones, Francesca

    2016-07-19

    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.

  13. 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 ...

  14. Seasonal behaviour of tidal inlets in a tropical monsoon area

    NARCIS (Netherlands)

    Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.

    2008-01-01

    Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modelled and discussed. Influences of river flow and wave climate on the inlet morphology are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic

  15. On the superposition of bedforms in a tidal channel

    DEFF Research Database (Denmark)

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

    2008-01-01

    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 ...

  16. Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation ofsecondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; howeve...

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

    Directory of Open Access Journals (Sweden)

    N.G. Koulouris

    2011-09-01

    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.

  18. Annular tidal regenerator engine for nuclear circulatory support systems

    International Nuclear Information System (INIS)

    Hagen, K.G.; Ruggles, A.E.; Fam, S.S.; Torti, V.A.

    1975-01-01

    In order to simplify the configuration of the tidal regenerator engine nuclear-powered circulatory support system, thereby drastically reducing its size and improving the intrinsic reliability, the engine has been redesigned. This redesign focuses on allowing power to be extracted at the low temperature end of the engine utilizing a piston-cylinder arrangement wherein all of the necessary heat transfer processes occur in the annular gap between the piston and cylinder. In all other respects the engine retains its basic characteristics as a hybrid between a Stirling engine and a Rankine engine. A significant advantage of the new arrangement is the ability to raise the superheat temperature limit from 650 0 F to over 900 0 F. This has yielded an increase in engine efficiency from 10 percent to 14 percent, and further increases are anticipated by utilizing an expansion and/or a binary version of the engine. The implantable system volume has been reduced by a factor of three and orientation insensitivity with respect to gravity has been demonstrated. Many system components have already demonstrated endurances of several thousand hours

  19. Admiralty Inlet Pilot Tidal Project Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Collar, Craig [Public Utility District No. 1 of Snohomish County, Everett, WA (United States)

    2015-09-14

    This document represents the final report for the Admiralty Inlet Pilot Tidal Project, located in Puget Sound, Washington, United States. The Project purpose was to license, permit, and install a grid-connected deep-water tidal turbine array (two turbines) to be used as a platform to gather operational and environmental data on tidal energy generation. The data could then be used to better inform the viability of commercial tidal energy generation from technical, economic, social, and environmental standpoints. This data would serve as a critical step towards the responsible advancement of commercial scale tidal energy in the United States and around the world. In late 2014, Project activities were discontinued due to escalating costs, and the DOE award was terminated in early 2015. Permitting, licensing, and engineering design activities were completed under this award. Final design, deployment, operation, and monitoring were not completed. This report discusses the results and accomplishments achieved under the subject award.

  20. Tidal Forces in Dyonic Reissner-Nördstrom Black Hole

    Science.gov (United States)

    Sharif, M.; Kousar, Lubna

    2018-03-01

    This paper investigates the tidal as well as magnetic charge effects produced in dyonic Reissner-Nordström black hole. We evaluate Newtonian radial acceleration using radial geodesics for freely falling test particles. We establish system of equations governing radial and angular tidal forces using geodesic deviation equation and discuss their solutions for bodies falling freely towards this black hole. The radial tidal force turns out to be compressing outside the event horizon whereas the angular tidal force changes sign between event and Cauchy horizons unlike Schwarzschild black hole. The radial geodesic component starts decreasing in dyonic Reissner-Nordström black hole unlike Schwarzschild case. We conclude that magnetic charge strongly affects the radial as well as angular components of tidal force.

  1. Understanding the Influence of Retention Basin on Tidal Dynamics in Tidal Estuaries

    Science.gov (United States)

    Kumar, Mohit; Schuttelaars, Henk; Roos, Pieter

    2014-05-01

    Both the tidal motion and suspended sediment concentration (SSC) in tidal embayments and estuaries are influenced by anthropogenic (e.g. deepening ) and natural changes. An example of such an estuary is the Ems estuary, situated on the border of the Netherlands and Germany. The mean tidal range towards the end of the Ems estuary has increased from 1.5m in the 1950s to more than 3m in the 1990s while the suspended concentration has increased by a factor 10. To possibly reduce these negative effects, the construction of retention basin(s) (RB) is considered. In this contribution, the influence of location and geometry of RBs on tidal dynamics and SSC is investigated. For this purpose, a three-dimensional semi-analytic idealized model is developed. This model is an extension of the model proposed by Winant (2007) to arbitrary domain and realistic bathymetry with partial slip boundary condition at the bottom. The sea surface elevation (SSE) is calculated numerically using a finite element method. Next, the three-dimensional velocities are calculated by combining the analytically calculated vertical profiles and the gradients of the SSE which are obtained numerically. Firstly, the influence of a RB on the tidal dynamics in an infinitely long, rectangular, frictionless estuary is considered. The SSE decreases when the RB is located between a node and a landward antinode, consistent with the work of Alebregtse et al. (2013). Secondly, an estuary of finite length is connected to a sea. By varying the width of the sea, not only the effect of the distance of the RB to the landward end plays a role, but also the distance to the open sea becomes important. Finally, we discuss the influence of a RB on the tidal motion and initial sediment transport, considering the Ems estuary with realistic bathymetry. Results show that the SSE at the landward end of the Ems estuary decreases for all locations of the RBs. This decrease is most pronounced for the RB which is closest to the end

  2. Spin-orbital Tidal Dynamics and Tidal Heating in the TRAPPIST-1 Multiplanet System

    Science.gov (United States)

    Makarov, Valeri V.; Berghea, Ciprian T.; Efroimsky, Michael

    2018-04-01

    We perform numerical simulations of the TRAPPIST-1 system of seven exoplanets orbiting a nearby M dwarf, starting with a previously suggested stable configuration. The long-term stability of this configuration is confirmed, but the motion of planets is found to be chaotic. The eccentricity values are found to vary within finite ranges. The rates of tidal dissipation and tidal evolution of orbits are estimated, assuming an Earth-like rheology for the planets. We find that under this assumption, the planets b, d, and e were captured in the 3:2 or higher spin–orbit resonances during the initial spin-down, but slipped further down into the 1:1 resonance. Depending on its rheology, the innermost planet b may be captured in a stable pseudosynchronous rotation. Nonsynchronous rotation ensures higher levels of tidal dissipation and internal heating. The positive feedback between the viscosity and the dissipation rate—and the ensuing runaway heating—are terminated by a few self-regulation processes. When the temperature is high and the viscosity is low enough, the planet spontaneously leaves the 3:2 resonance. Further heating is stopped either by passing the peak dissipation or by the emergence of partial melt in the mantle. In the post-solidus state, the tidal dissipation is limited to the levels supported by the heat transfer efficiency. The tides on the host star are unlikely to have had a significant dynamical impact. The tides on the synchronized inner planets tend to reduce these planets’ orbital eccentricity, possibly contributing thereby to the system’s stability.

  3. A improved tidal method without water level

    Science.gov (United States)

    Luo, xiaowen

    2017-04-01

    Now most tide are obtained use water Level and pressure type water gage, but it is difficult to install them and reading is in low accuracy in this method . In view of above-mentioned facts, In order to improve tide accuracy, A improved method is introduced.sea level is obtained in given time using high-precision GNSS buoy combined instantaneous position from pressure gage. two steps are as following, (1) the GNSS time service is used as the source of synchronization reference in tidal measurement; (2) centimeter-level sea surface positions are obtained in real time using difference GNSS The improved method used in seafloor topography survey,in 145 cross points, 95% meet the requirements of the Hydrographic survey specification. It is effective method to obtain higher accuracy tide.

  4. Design and optimization of tidal turbine airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, F. [ECN Wind Energy, Petten (Netherlands)

    2011-07-15

    In order to increase the ratio of energy capture to the loading and thereby to reduce cost of energy, the use of specially tailored airfoils is needed. This work is focused on the design of an airfoil for marine application. Firstly, the requirements for this class of airfoils are illustrated and discussed with reference to the requirements for wind turbine airfoils. Then, the design approach is presented. This is a numerical optimization scheme in which a gradient based algorithm is used, coupled with RFOIL solver and a composite Bezier geometrical parameterization. A particularly sensitive point is the choice and implementation of constraints; in order to formalize in the most complete and effective way the design requirements, the effects of activating specific constraints are discussed. Particularly importance is given to the cavitation phenomenon. Finally, a numerical example regarding the design of a high efficiency, tidal turbine airfoil is illustrated and the results are compared with existing turbine airfoils.

  5. Assimilating data into open ocean tidal models

    Science.gov (United States)

    Kivman, Gennady A.

    The problem of deriving tidal fields from observations by reason of incompleteness and imperfectness of every data set practically available has an infinitely large number of allowable solutions fitting the data within measurement errors and hence can be treated as ill-posed. Therefore, interpolating the data always relies on some a priori assumptions concerning the tides, which provide a rule of sampling or, in other words, a regularization of the ill-posed problem. Data assimilation procedures used in large scale tide modeling are viewed in a common mathematical framework as such regularizations. It is shown that they all (basis functions expansion, parameter estimation, nudging, objective analysis, general inversion, and extended general inversion), including those (objective analysis and general inversion) originally formulated in stochastic terms, may be considered as utilizations of one of the three general methods suggested by the theory of ill-posed problems. The problem of grid refinement critical for inverse methods and nudging is discussed.

  6. Will Restored Tidal Marshes Be Sustainable?

    Directory of Open Access Journals (Sweden)

    Michelle Orr

    2003-10-01

    Full Text Available We assess whether or not restored marshes in the San Francisco Estuary are expected to be sustainable in light of future landscape scale geomorphic processes given typical restored marsh conditions. Our assessment is based on a review of the literature, appraisal of monitoring data for restored marshes, and application of vertical accretion modeling of organic and inorganic sedimentation. Vertical accretion modeling suggests that salt marshes in San Pablo Bay will be sustainable for moderate relative sea level rise (3 to 5 mm yr-1 and average sediment supply (c. 100 mg L-1. Accelerated relative sea level rise (above 6 mm yr-1 and/or reduced sediment supply (50 mg L-1 will cause lowering of the marsh surface relative to the tide range and may cause shifts from high to low marsh vegetation by the year 2100. Widespread conversion of marsh to mudflat-"ecological drowning"-is not expected within this time frame. Marshes restored at lower elevations necessary to aid the natural development of channel systems (c. 0.5 m below mean higher high water are predicted to accrete to high marsh elevations by the year 2100 for moderate relative sea level rise and sediment supply conditions. Existing rates of sediment accretion in restored fresh water tidal marshes of the Delta of greater than 9 mm yr-1 and slightly lower drowning elevations suggest that these marshes will be resilient against relatively high rates of sea level rise. Because of higher rates of organic production, fresh water marshes are expected to be less sensitive to reduced sediment availability than salt marshes. The ultimate long-term threat to the sustainability of tidal marshes is the interruption of coastal rollover-the process by which landward marsh expansion in response to sea level rise compensates for shoreline erosion. Bay front development now prevents most landward marsh expansion, while shoreline erosion is expected to accelerate as sea level rises.

  7. TIDALLY DRIVEN DYNAMOS IN A ROTATING SPHERE

    International Nuclear Information System (INIS)

    Cébron, D.; Hollerbach, R.

    2014-01-01

    Large-scale planetary or stellar magnetic fields generated by a dynamo effect are mostly attributed to flows forced by buoyancy forces in electrically conducting fluid layers. However, these large-scale fields may also be controlled by tides, as previously suggested for the star τ-boo, Mars, or the early Moon. By simulating a small local patch of a rotating fluid, Barker and Lithwick have recently shown that tides can drive small-scale dynamos by exciting a hydrodynamic instability, the so-called elliptical (or tidal) instability. By performing global magnetohydrodynamic simulations of a rotating spherical fluid body, we investigate if this instability can also drive the observed large-scale magnetic fields. We are thus interested in the dynamo threshold and the generated magnetic field in order to test if such a mechanism is relevant for planets and stars. Rather than solving the problem in a geometry deformed by tides, we consider a spherical fluid body and add a body force to mimic the tidal deformation in the bulk of the fluid. This allows us to use an efficient spectral code to solve the magnetohydrodynamic problem. We first compare the hydrodynamic results with theoretical asymptotic results and numerical results obtained in a truly deformed ellipsoid, which confirms the presence of elliptical instability. We then perform magnetohydrodynamic simulations and investigate the dynamo capability of the flow. Kinematic and self-consistent dynamos are finally simulated, showing that the elliptical instability is capable of generating a dipole-dominated large-scale magnetic field in global simulations of a fluid rotating sphere

  8. Dynamics of Tidally Locked, Ultrafast Rotating Atmospheres

    Science.gov (United States)

    Tan, Xianyu; Showman, Adam P.

    2017-10-01

    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.

  9. Dwarf Galaxies Swimming in Tidal Tails

    Science.gov (United States)

    2005-01-01

    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. Ambient Noise in an Urbanized Tidal Channel

    Science.gov (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

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

    Directory of Open Access Journals (Sweden)

    Talchabhadel Rocky

    2016-01-01

    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.

  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.

    Science.gov (United States)

    Thiébaut, Maxime; Sentchev, Alexei

    2015-04-01

    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. 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

    2015-12-01

    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

  14. Observed tidal braking in the earth/moon/sun system

    Science.gov (United States)

    Christodoulidis, D. C.; Smith, D. E.; Williamson, R. G.; Klosko, S. M.

    1987-01-01

    The low degree and order terms in the spherical harmonic model of the tidal potential were observed through the perturbations which are induced on near-earth satellite orbital motions. Evaluations of tracking observations from 17 satellites and a GEM-T1 geopotential model were used in the tidal recovery which was made in the presence of over 600 long-wavelength coefficients from 32 major and minor tides. Wahr's earth tidal model was used as a basis for the recovery of the ocean tidal terms. Using this tidal model, the secular change in the moon's mean motion due to tidal dissipation was found to be -25.27 + or - 0.61 arcsec/century squared. The estimation of lunar acceleration agreed with that observed from lunar laser ranging techniques (-24.9 + or - 1.0 arcsec/century squared), with the corresponding tidal braking of earth's rotation being -5.98 + or - 0.22 x 10 to the minus 22 rad/second squared. If the nontidal braking of the earth due to the observed secular change in the earth's second zonal harmonic is considered, satellite techniques yield a total value of the secular change of the earth's rotation rate of -4.69 + or - 0.36 x 10 to the minus 22 rad/second squared.

  15. Derivation of Delaware Bay tidal parameters from space shuttle photography

    International Nuclear Information System (INIS)

    Zheng, Quanan; Yan, Xiaohai; Klemas, V.

    1993-01-01

    The tide-related parameters of the Delaware Bay are derived from space shuttle time-series photographs. The water areas in the bay are measured from interpretation maps of the photographs with a CALCOMP 9100 digitizer and ERDAS Image Processing System. The corresponding tidal levels are calculated using the exposure time annotated on the photographs. From these data, an approximate function relating the water area to the tidal level at a reference point is determined. Based on the function, the water areas of the Delaware Bay at mean high water (MHW) and mean low water (MLW), below 0 m, and for the tidal zone are inferred. With MHW and MLW areas and the mean tidal range, the authors calculate the tidal influx of the Delaware Bay, which is 2.76 x 1O 9 m 3 . Furthermore, the velocity of flood tide at the bay mouth is determined using the tidal flux and an integral of the velocity distribution function at the cross section between Cape Henlopen and Cape May. The result is 132 cm/s, which compares well with the data on tidal current charts

  16. Vertical Distribution of Tidal Flow Reynolds Stress in Shallow Sea

    Institute of Scientific and Technical Information of China (English)

    SONG Zhi-yao; NI Zhi-hui; LU Guo-nian

    2009-01-01

    Based on the results of the tidal flow Reynolds stresses of the field observations,indoor experiments,and numerical models,the parabolic distribution of the tidal flow Reynolds stress is proposed and its coefficients are determined theoretically in this paper.Having been well verified with the field data and experimental data,the proposed distribution of Reynolds stress is also compared with numerical model results,and a good agreement is obtained,showing that this distribution can well reflect the basic features of Reynolds stress deviating from the linear distribution that is downward when the tidal flow is of acceleration,upward when the tidal flow is of deceleration.Its dynamics cause is also discussed preliminarily and the influence of the water depth is pointed out from the definition of Reynolds stress,turbulent generation,transmission,and so on.The established expression for the vertical distribution of the tidal flow Reynolds stress is not only simple and explicit,but can also well reflect the features of the tidal flow acceleration and deceleration for further study on the velocity profile of tidal flow.

  17. Diurnal, semidiurnal, and fortnightly tidal components in orthotidal proglacial rivers.

    Science.gov (United States)

    Briciu, Andrei-Emil

    2018-02-22

    The orthotidal rivers are a new concept referring to inland rivers influenced by gravitational tides through the groundwater tides. "Orthotidal signals" is intended to describe tidal signals found in inland streamwaters (with no oceanic input); these tidal signals were locally generated and then exported into streamwaters. Here, we show that orthotidal signals can be found in proglacial rivers due to the gravitational tides affecting the glaciers and their surrounding areas. The gravitational tides act on glacier through earth and atmospheric tides, while the subglacial water is affected in a manner similar to the groundwater tides. We used the wavelet analysis in order to find tidally affected streamwaters. T_TIDE analyses were performed for discovering the tidal constituents. Tidal components with 0.95 confidence level are as follows: O1, PI1, P1, S1, K1, PSI1, M2, T2, S2, K2, and MSf. The amplitude of the diurnal tidal constituents is strongly influenced by the daily thermal cycle. The average amplitude of the semidiurnal tidal constituents is less altered and ranges from 0.0007 to 0.0969 m. The lunisolar synodic fortnightly oscillation, found in the time series of the studied river gauges, is a useful signal for detecting orthotidal rivers when using noisier data. The knowledge of the orthotidal oscillations is useful for modeling fine resolution changes in rivers.

  18. Magnetic fields driven by tidal mixing in radiative stars

    Science.gov (United States)

    Vidal, Jérémie; Cébron, David; Schaeffer, Nathanaël; Hollerbach, Rainer

    2018-04-01

    Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 per cent 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.

  19. Device interactions in reducing the cost of tidal stream energy

    International Nuclear Information System (INIS)

    Vazquez, A.; Iglesias, G.

    2015-01-01

    Highlights: • Numerical modelling is used to estimate the levelised cost of tidal stream energy. • As a case study, a model of Lynmouth (UK) is implemented and successfully validated. • The resolution of the model allows the demarcation of individual devices on the model grid. • Device interactions reduce the available tidal resource and the cost increases significantly. - Abstract: The levelised cost of energy takes into account the lifetime generated energy and the costs associated with a project. The objective of this work is to investigate the effects of device interactions on the energy output and, therefore, on the levelised cost of energy of a tidal stream project, by means of numerical modelling. For this purpose, a case study is considered: Lynmouth (North Devon, UK), an area in the Bristol Channel in which the first tidal stream turbine was installed − a testimony of its potential as a tidal energy site. A state-of-the-art hydrodynamics model is implemented on a high-resolution computational grid, which allows the demarcation of the individual devices. The modification to the energy output resulting from interaction between turbines within the tidal farm is thus resolved for each individual turbine. The results indicate that significant changes in the levelised cost of energy values, of up to £0.221 kW h −1 , occur due to the aforementioned modifications, which should not be disregarded if the cost of tidal stream energy is to be minimised

  20. Large tidal plants may supply 1,000 TWh / year

    International Nuclear Information System (INIS)

    Lemperiere, F.

    2006-10-01

    Many studies of tidal plants have been made fifty years ago: they were usually devoted to sites with average tidal head over 6 m and reduced works at sea: estuaries such as La Rance (France) or Severn (U.K.) were favoured: preferred corresponding operation was using flow from a high basin to low sea level, supplying power 4 hours from 12. Such solutions had 2 drawbacks: power supply poorly adapted to needs and modified shore tidal ecosystems. Beyond that the power cost was usually higher than from thermal plants and very few plants were built, the main one being the Rance plant in France supplying 0,5 TWh/year with 240 MW. The world theoretical tidal potential is in the same range as the traditional hydropower potential. A new approach of tidal plants based upon solutions existing now and using new operating methods substantiates the possibility of over 1,000 TWh/year of cost efficient tidal energy with limited environmental impact and power supply well adapted to requirements. Over 15 countries may be involved. Tidal plants with heads as low as 4 m may be cost efficient. (author)

  1. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak İçindekiler

    2016-12-01

    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

  2. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2017-12-01

    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

  3. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2018-04-01

    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

  4. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2017-08-01

    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

  5. Kapak ve İçindekiler

    Directory of Open Access Journals (Sweden)

    Kapak ve İçindekiler

    2017-04-01

    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

  6. Tidal day organic and inorganic material flux of ponds in the Liberty Island freshwater tidal wetland.

    Science.gov (United States)

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

    2015-01-01

    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

  7. A Summary of the San Francisco Tidal Wetlands Restoration Series

    Directory of Open Access Journals (Sweden)

    Larry R. Brown

    2003-10-01

    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.

  8. Suspended particulate matter flocculation in a natural tidal wetland located in the San Francisco Estuary

    Science.gov (United States)

    Saraceno, J.; Bergamaschi, B. A.; Wright, S. A.; Boss, E.; Downing, B. D.; Fleck, J.; Ganju, N. K.

    2011-12-01

    Suspended mineral and algal particles together comprise suspended particulate matter (SPM). The SPM size distribution influences the quantity and color of light penetration and the adsorption and transport of contaminants such as pesticides and metals. It is widely known that interaction with wetlands alters the size distribution and quality of particles through local primary production, differential settling and particle aggregation, however, our understanding of how tidal wetland processes affect SPM quantity and size spectra has been hampered by the difficulty of directly observing these parameters at tidal time scales. To evaluate how SPM concentration and size varied over tidal time scales and to better understand the relationship between organic matter and sediment characteristics, simultaneous measurements of dissolved organic matter, SPM concentration and organic content as well as in situ surrogates of particle concentration (turbidity, particulate attenuation, volume concentration) and particle size (laser diffraction) were carried out with measurements of current velocity (acoustic Doppler velocity meter) in the main channel of Brown's Island located in the western San Joaquin/Sacramento River Delta, CA. The study period coincided with high estuary sediment levels following a significant precipitation runoff event. In the Brown Island wetland, particle concentration and size dynamics were tied to variations in water level and velocity. Turbidity and attenuation covaried with the volume concentration of particles smaller than 33 um, which on average represented greater than 50% of particle population by volume. On average, these SPM concentration surrogates were three times higher in flood water than in ebb water; consistent with a loss of fine particles on the island. Following the highest flood tide, the decrease in fine particles was coincident with an increase in the concentration of particles larger than 130 um; a finding consistent with particle

  9. Tidal energy UK Government R and D programme. Final report

    International Nuclear Information System (INIS)

    Craig, J.W.; Davies, L.M.; Allington, M.A.

    1996-05-01

    The United Kingdom Government's research programme into the feasibility of exploiting tidal power for electricity generation in Britain's estuaries is described in this document. The history of the research is included from the Severn Barrage Committee in 1978 to the conclusion of the tidal energy barrages programme in 1994. The programme sought to reduce uncertainty on costs, technical performance and environmental and regional effects, in order to firm up on decisions on whether to construct certain specific barrages. It was concluded that, while technically feasible, tidal power from barrages, was and will continue to be uneconomic compared with other energy sources. Other renewable technologies would receive further research. (UK)

  10. Virtual Seafloor Reduces Internal Wave Generation by Tidal Flow

    Science.gov (United States)

    Zhang, Likun; Swinney, Harry L.

    2014-03-01

    Our numerical simulations of tidal flow of a stratified fluid over periodic knife-edge ridges and random topography reveal that the time-averaged tidal energy converted into internal gravity wave radiation arises only from the section of a ridge above a virtual seafloor. The average radiated power is approximated by the power predicted by linear theory if the height of the ridge is measured relative to the virtual floor. The concept of a virtual floor can extend the applicability of linear theory to global predictions of the conversion of tidal energy into internal wave energy in the oceans.

  11. Assessment of Kinetic Tidal Energy Resources Using SELFE

    OpenAIRE

    Manasa Ranjan Behera; Pavel Tkalich

    2014-01-01

    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 fo...

  12. Geometric properties of hydraulic-relevant tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Ferret, Yann; Lefebvre, Alice

    2013-01-01

    of bedform genesis and dynamics is not yet available, various empirical descriptors have been formulated based on extensive data compilations (e.g. Allen, 1968; Flemming, 1988; Francken, 2004). Mean bedform heights H and lengths L were found to scale, e.g H = a * L b in which a=0.03-0.07 and b=0.7-0.9. Due...... 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...

  13. 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

    2015-07-01

    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.

  14. Linking freshwater tidal hydrology to carbon cycling in bottomland hardwood wetlands

    Science.gov (United States)

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

    2016-01-01

    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...

  15. Anonimlik deneyimi ve sosyal medya etkisi

    OpenAIRE

    Aslan, M.Gökhan

    2012-01-01

    116 pages Anonimlik bir kelime olarak çağrıştırdığı ilk anlamlarının ötesinde çok katmanlı bir deneyimi temsil etmektedir. Bu tez çalışmasında amaçlanan, ilk adımda anonimliği sözlük anlamından itibaren başlayarak kapsamlı bir tanımsal analize tabi tutmaktır. Bu analiz dahilinde anonimliğin nitelikleri ve türleri bir bütün olarak ele alınmaktadır. İkinci adımda ise anonimliğin farklı iletişim biçimlerindeki dönüşümünün, paralel sosyal ve teknolojik değişimlerle beraber izi sürülerek son ba...

  16. 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...

  17. Carbohydrate secretion by phototrophic communities in tidal sediments

    NARCIS (Netherlands)

    de Winder, B.; Staats, N.; Stal, L.J.; Paterson, D.M.

    1999-01-01

    Two different benthic phototrophic communities on tidal flats were investigated for their carbohydrate content and distribution. Carbohydrates were analysed as two operationally defined fractions, related to the difficulty of extraction from the sediment matrix. Water-soluble (colloidal) and EDTA-

  18. Anticorrosion and halobios control for tidal power generating units

    International Nuclear Information System (INIS)

    Shen, J C; Ding, L X

    2012-01-01

    The anticorrosion and halobios control is the key techniquesrelated to the safety and durability of tidal power generating units. The technique of material application, antifouling coating and cathodic protection are often adopted. The technical research, application, updating and development are carried on Jiangxia Tidal Power Station, which is based on the old Unit 1-Unit 5 operated for nearly 30 years, and the new Unit 6 operated in 2007. It is found that stainless steeland the antifouling coating used in Unit 1- Unit 5 are very effective, but cathodic protection is often likely to fail because of the limitation of structure and installation. Analyses and studies for anticorrosion and halobios control techniques of tidal power generating units according to theory, experience and actual effects have been done, which can be for reference to the tidal power station designers and builders.

  19. N-Body Simulations of Tidal Encounters between Stellar Systems

    Indian Academy of Sciences (India)

    tribpo

    Saleh Mohammed Alladin† International Centre for Theoretical Physics, ... concentrate on how the tidal field of the primary changes the mass distribution, energy and angular momentum ..... International School for Advanced Studies, Trieste.

  20. Sears Point Tidal Marsh Restoration Project: Phase I

    Science.gov (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.

  1. Measuring and modeling exposure from environmental radiation on tidal flats

    International Nuclear Information System (INIS)

    Gould, T.J.; Hess, C.T.

    2005-01-01

    To examine the shielding effects of the tide cycle, a high pressure ion chamber was used to measure the exposure rate from environmental radiation on tidal flats. A theoretical model is derived to predict the behavior of exposure rate as a function of time for a detector placed one meter above ground on a tidal flat. The numerical integration involved in this derivation results in an empirical formula which implies exposure rate ∝tan-1(sint). We propose that calculating the total exposure incurred on a tidal flat requires measurements of only the slope of the tidal flat and the exposure rate when no shielding occurs. Experimental results are consistent with the model

  2. The structure of turbulence in a rapid tidal flow.

    Science.gov (United States)

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

    2017-08-01

    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.

  3. On tidal phenomena in a strong gravitational field

    International Nuclear Information System (INIS)

    Mashoon, B.

    1975-01-01

    A simple framework based on the concept of quadrupole tidal potential is presented for the calculation of tidal deformation of an extended test body in a gravitational field. This method is used to study the behavior of an initially faraway nonrotating spherical body that moves close to a Schwarzschild or an extreme Kerr black hole. In general, an extended body moving in an external gravitational field emits gravitational radiation due to its center of mass motion, internal tidal deformation, and the coupling between the internal and center of mass motions. Estimates are given of the amount of tidal radiation emitted by the body in the gravitational fields considered. The results reported in this paper are expected to be of importance in the dynamical evolution of a dense stellar system with a massive black hole in its center

  4. On tidal radius determination for a globular cluster

    International Nuclear Information System (INIS)

    Ninkovic, S.

    1985-01-01

    A tidal radius determination for a globular cluster based on its density minimum, which is caused by the galactic tidal forces and derivable from a model of the Galaxy, is proposed. Results obtained on the basis of the Schmidt model for two clusters are in a satisfactory agreement with those obtained earlier by means of other methods. A mass determination for the clusters through the tidal radius, when the latter one is identified with the cluster perigalactic distance, yields unusually large mass values. Probably, the tidal radius should be identified with the instantaneous galactocentric distance. Use of models more recent than the Schmidt one indicates that a globular cluster may contain a significant portion of an invisible interstellar matter. (author)

  5. Sears Point Tidal Marsh Restoration Project: Phase II

    Science.gov (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.

  6. Observation of Tidal Effects on LWIR Radiance Above the Mesopause

    National Research Council Canada - National Science Library

    Wintersteiner, Peter

    2007-01-01

    ..., and season The local-time dependence, in particular, suggests a role for atmospheric tides using a tidal model, Global Scale Wave Model, and our non-GTE ARC rode, we modeled the 15 Om radiance...

  7. Emerson Parcel of Dutch Slough Tidal Marsh Restoration Project

    Science.gov (United States)

    Information about the SFBWQP Emerson Parcel of Dutch Slough Tidal Marsh Restoration Project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  8. South Bay Salt Pond Tidal Wetland Restoration Phase II Planning

    Science.gov (United States)

    Information about the SFBWQP South Bay Salt Pond Tidal Wetland Restoration Phase II Planning project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic re

  9. Inundation Mapping Tidal Surface - Mean Higher High Water

    Data.gov (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...

  10. Tidal variations in the Sundarbans Estuarine System, India

    Indian Academy of Sciences (India)

    gle channel; estuaries of this type are by far the most numerous .... the observation stations and describe the methods used. ...... The Cen- tral Inland Fisheries Research Institute, in their .... Qualitative information regarding tidal levels and the ...

  11. 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

    2016-08-01

    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.

  12. BProVe: Tool support for business process verification

    DEFF Research Database (Denmark)

    Corradini, Flavio; Fornari, Fabrizio; Polini, Andrea

    2017-01-01

    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...

  13. Heartbeat stars and the ringing of tidal pulsations

    OpenAIRE

    García, RA; Hambleton, K; Kurtz, DW; Prsa, A; Fuller, J; Thompson (SU), S; Ballot, J

    2015-01-01

    With the advent of high precision photometry from satellites such as Kepler and CoRoT, a whole new layer of interesting and astounding astronomical objects has been revealed: heartbeat stars are an example of such objects. Heartbeat stars are eccen- tric ellipsoidal variables that undergo strong tidal interactions when the stars are almost in contact at the time of closest approach. These interactions deform of the stars and cause a notable light curve variation in the form of a tidal pulse. ...

  14. Bedload transport in an inlet channel during a tidal cycle

    DEFF Research Database (Denmark)

    Ernstsen, V. B.; Becker, M.; Winter, C.

    2007-01-01

      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....

  15. Tidal Current Energy Resource Assessment Around Buton Island, Southeast Sulawesi, Indonesia

    OpenAIRE

    Ribal, Agustinus; Amir, Amir Kamal; Toaha, Syamsuddin; Kusuma, Jeffry; Khaeruddin

    2017-01-01

    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...

  16. From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Pairs

    Science.gov (United States)

    Knierman, K. A.; Gallagher, S. C.; Charlton, J. C.; Hunsberger, S. D.; Whitmore, B. C.; Kundu, A.; Hibbard, J. E.; Zaritsky, D. F.

    2001-05-01

    Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic ``Toomre Sequence'' mergers: NGC 4038/9 (``Antennae''), NGC 3256, NGC 3921, and NGC 7252 (``Atoms for Peace'') have been studied in order to explore how the star formation depends upon the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence, and include HI--rich and HI--poor environments. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of young clusters lying along both tails, similar to those found in the inner region of the merger. In contrast, NGC 4038/9 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters that are concentrated in certain regions of the tail, and particularly in the prominent tidal dwarfs in the eastern and western tails of NGC 7252. The two cluster--rich tails of NGC 3256 are not distinguished from the others by their ages or by their total HI masses. We acknowledge support from NASA through STScI, and from NSF for an REU supplement for Karen Knierman.

  17. Use of geomorphic, hydrologic, and nitrogen mass balance data to model ecosystem nitrate retention in tidal freshwater wetlands

    Directory of Open Access Journals (Sweden)

    E. D. Seldomridge

    2012-07-01

    Full Text Available Geomorphic characteristics have been used as scaling parameters to predict water and other fluxes in many systems. In this study, we combined geomorphic analysis with in-situ mass balance studies of nitrate retention (NR to evaluate which geomorphic scaling parameters best predicted NR in a tidal freshwater wetland ecosystem. Geomorphic characteristics were measured for 267 individual marshes that constitute the freshwater tidal wetland ecosystem of the Patuxent River, Maryland. Nitrate retention was determined from mass balance measurements conducted at the inlets of marshes of varying size (671, 5705, and 536 873 m2 over a period of several years. Mass balance measurements indicate that NR is proportional to total water flux over the tidal cycle. Relationships between estimated tidal prism (calculated water volume for spring tides and various geomorphic parameters (marsh area, total channel length, and inlet width were defined using measurements from air photos and compared to field data. From these data, NR equations were determined for each geomorphic parameter, and used to estimate NR for all marshes in the ecosystem for a reference spring (high tide. The resulting ecosystem NR estimates were evaluated for (a accuracy and completeness of geomorphic data, (b relationship between the geomorphic parameters and hydrologic flux, and (c the ability to adapt the geomorphic parameter to varying tidal conditions. This analysis indicated that inlet width data were the most complete and provided the best estimate of ecosystem nitrate retention. Predictions based on marsh area were significantly lower than the inlet width-based predictions. Cumulative probability distributions of nitrate retention indicate that the largest 3–4% of the marshes retained half of the total nitrate for the ecosystem.

  18. Dynamical and photometric models of star formation in tidal tails

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1990-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broadband photometric evolutionary code. Test particles are initially placed in circular orbits around a softened point mass and then perturbed by a companion passing in a parabotic orbit. During the passage, the density evolution of the galaxy is examined both in regions within the disk and in selected comoving regions in the tidal features. Even without the inclusion of self-gravity and hydrodynamics, regions of compression form inside the disk, along the tidal tail, and in the tidal bridge causing local density increases of up to 500 percent. By assuming that the density changes relate to the star-formation rate via a Schmidt (1959) law, limits on the density changes needed to make detectable changes in the colors are calculated. A spiral galaxy population is synthesized and the effects of modest changes in the star-formation rate are explored using a broadband photometric evolutionary code. Density changes similar to those found in the dynamical models will cause detectable changes in the colors of a stellar population. From these models, it is determined that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. 52 refs

  19. Tidal Turbines’ Layout in a Stream with Asymmetry and Misalignment

    Directory of Open Access Journals (Sweden)

    Nicolas Guillou

    2017-11-01

    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.

  20. 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......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 accuracy of the global tidal models decreases by several centimeters in the Polar Regions. In particular, it has a large impact on the quality of the satellite altimeter sea surface heights in these regions (ERS1/2, Envisat, CryoSat-2, SARAL/AltiKa and the future Sentinel-3 mission). Better knowledge......-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...

  1. Will Tidal Wetland Restoration Enhance Populations of Native Fishes?

    Directory of Open Access Journals (Sweden)

    Larry R. Brown

    2003-10-01

    Full Text Available Restoration of tidal wetlands might enhance populations of native fishes in the San Francisco Estuary of California. The purpose of this paper is to: (1 review the currently available information regarding the importance of tidal wetlands to native fishes in the San Francisco Estuary, (2 construct conceptual models on the basis of available information, (3 identify key areas of scientific uncertainty, and (4 identify methods to improve conceptual models and reduce uncertainty. There are few quantitative data to suggest that restoration of tidal wetlands will substantially increase populations of native fishes. On a qualitative basis, there is some support for the idea that tidal wetland restoration will increase populations of some native fishes; however, the species deriving the most benefit from restoration might not be of great management concern at present. Invasion of the San Francisco Estuary by alien plants and animals appears to be a major factor in obscuring the expected link between tidal wetlands and native fishes. Large-scale adaptive management experiments (>100 hectares appear to be the best available option for determining whether tidal wetlands will provide significant benefit to native fishes. Even if these experiments are unsuccessful at increasing native fish populations, the restored wetlands should benefit native birds, plants, and other organisms.

  2. The prediction of the hydrodynamic performance of tidal current turbines

    International Nuclear Information System (INIS)

    Xiao, B Y; Zhou, L J; Xiao, Y X; Wang, Z W

    2013-01-01

    Nowadays tidal current energy is considered to be one of the most promising alternative green energy resources and tidal current turbines are used for power generation. Prediction of the open water performance around tidal turbines is important for the reason that it can give some advice on installation and array of tidal current turbines. This paper presents numerical computations of tidal current turbines by using a numerical model which is constructed to simulate an isolated turbine. This paper aims at studying the installation of marine current turbine of which the hydro-environmental impacts influence by means of numerical simulation. Such impacts include free-stream velocity magnitude, seabed and inflow direction of velocity. The results of the open water performance prediction show that the power output and efficiency of marine current turbine varies from different marine environments. The velocity distribution should be clearly and the suitable unit installation depth and direction be clearly chosen, which can ensure the most effective strategy for energy capture before installing the marine current turbine. The findings of this paper are expected to be beneficial in developing tidal current turbines and array in the future

  3. Tidal pumping facilitates dissimilatory nitrate reduction in intertidal marshes

    Science.gov (United States)

    Zheng, Yanling; Hou, Lijun; Liu, Min; Liu, Zhanfei; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Yu, Chendi; Wang, Rong; Jiang, Xiaofen

    2016-01-01

    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. PMID:26883983

  4. Assessment of Kinetic Tidal Energy Resources Using SELFE

    Directory of Open Access Journals (Sweden)

    Manasa Ranjan Behera

    2014-09-01

    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.

  5. The environmental interactions of tidal and wave energy generation devices

    International Nuclear Information System (INIS)

    Frid, Chris; Andonegi, Eider; Depestele, Jochen; Judd, Adrian; Rihan, Dominic; Rogers, Stuart I.; Kenchington, Ellen

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: ► We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. ► Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. ► Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. ► Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  6. Tidal energy, a renewable energy within hand reach

    International Nuclear Information System (INIS)

    Danielo, O.

    2011-01-01

    Tide energy and oceanic current energy represent a strong potentiality for a few countries in the world including France. In the domain of tidal energy there are 2 strategies. The first one is based on the search for the lowest power production cost in order to contribute efficiently to the country's energy mix. Generally this strategy leads to the construction of tidal dams. The second strategy is based on the search for the lowest environmental impact. This strategy is economically competitive only in places where electrical power is expensive like isolated islands. This strategy is illustrated by the tidal power station of the Alderney island. In fact the amount of energy delivered by a tidal power station depends on the rise of the tide and on the surface of the dam. It appears that tidal dams require less surface that hydroelectric power plants. The energy of oceanic currents like Gulf Stream or the thermal energy of oceans or wave power are very little exploited now but represent a potentiality higher by several orders of magnitude than tidal energy. (A.C.)

  7. Tidal interaction of black holes and Newtonian viscous bodies

    International Nuclear Information System (INIS)

    Poisson, Eric

    2009-01-01

    The tidal interaction of a (rotating or nonrotating) black hole with nearby bodies produces changes in its mass, angular momentum, and surface area. Similarly, tidal forces acting on a Newtonian, viscous body do work on the body, change its angular momentum, and part of the transferred gravitational energy is dissipated into heat. The equations that describe the rate of change of the black-hole mass, angular momentum, and surface area as a result of the tidal interaction are compared with the equations that describe how the tidal forces do work, torque, and produce heat in the Newtonian body. The equations are strikingly similar, and unexpectedly, the correspondence between the Newtonian-body and black-hole results is revealed to hold in near-quantitative detail. The correspondence involves the combination k 2 τ of 'Love quantities' that incorporate the details of the body's internal structure; k 2 is the tidal Love number, and τ is the viscosity-produced delay between the action of the tidal forces and the body's reaction. The combination k 2 τ is of order GM/c 3 for a black hole of mass M; it does not vanish, in spite of the fact that k 2 is known to vanish individually for a nonrotating black hole.

  8. TWO NEW TIDALLY DISTORTED WHITE DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Hermes, J. J.; Montgomery, M. H.; Winget, D. E. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Brown, Warren R., E-mail: jjhermes@astro.as.utexas.edu [Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138 (United States)

    2012-04-10

    We identify two new tidally distorted white dwarfs (WDs), SDSS J174140.49+652638.7 and J211921.96-001825.8 (hereafter J1741 and J2119). Both stars are extremely low mass (ELM, {<=} 0.2 M{sub Sun }) WDs in short-period, detached binary systems. High-speed photometric observations obtained at the McDonald Observatory reveal ellipsoidal variations and Doppler beaming in both systems; J1741, with a minimum companion mass of 1.1 M{sub Sun }, has one of the strongest Doppler beaming signals ever observed in a binary system (0.59% {+-} 0.06% amplitude). We use the observed ellipsoidal variations to constrain the radius of each WD. For J1741, the star's radius must exceed 0.074 R{sub Sun }. For J2119, the radius exceeds 0.10 R{sub Sun }. These indirect radius measurements are comparable to the radius measurements for the bloated WD companions to A-stars found by the Kepler spacecraft, and they constitute some of the largest radii inferred for any WD. Surprisingly, J1741 also appears to show a 0.23% {+-} 0.06% reflection effect, and we discuss possible sources for this excess heating. Both J1741 and J2119 are strong gravitational wave sources, and the time-of-minimum of the ellipsoidal variations can be used to detect the orbital period decay. This may be possible on a timescale of a decade or less.

  9. Formation and evolution of tidal binary systems

    International Nuclear Information System (INIS)

    Mcmillan, S.L.W.; Mcdermott, P.N.; Taam, R.E.

    1987-01-01

    Cross sections for the tidal capture binary formation process are calculated for a variety of stellar models. The formalism used in the determination of the energy dissipated by a close encounter between two unbound stars and the associated capture cross sections are reviewed. The case of an n = 3/2 polytropic structure is calculated with the formalism, and the behavior of realistic stellar models is considered, including Population II main-sequence stars with masses of 0.4, 0.8, and 1.5 solar. The calculation is repeated for a slightly evolved 0.8 solar mass star just as it begins to leave the main sequence, and the behavior of more evolved stars is discussed. A quasi-adiabatic analysis is used to estimate the time scale on which the pulsation energy is actually dissipated internally or radiated away. This analysis also indicates where in the star most of the dissipation takes place, allowing the stellar response to be estimated by including the heating in the equations of stellar structure. 41 references

  10. Tidal Love Numbers of Neutron Stars

    International Nuclear Information System (INIS)

    Hinderer, Tanja

    2008-01-01

    For a variety of fully relativistic polytropic neutron star models we calculate the star's tidal Love number k 2 . Most realistic equations of state for neutron stars can be approximated as a polytrope with an effective index n ∼ 0.5-1.0. The equilibrium stellar model is obtained by numerical integration of the Tolman-Oppenheimer-Volkhov equations. We calculate the linear l = 2 static perturbations to the Schwarzschild spacetime following the method of Thorne and Campolattaro. Combining the perturbed Einstein equations into a single second-order differential equation for the perturbation to the metric coefficient g tt and matching the exterior solution to the asymptotic expansion of the metric in the star's local asymptotic rest frame gives the Love number. Our results agree well with the Newtonian results in the weak field limit. The fully relativistic values differ from the Newtonian values by up to ∼24%. The Love number is potentially measurable in gravitational wave signals from inspiralling binary neutron stars.

  11. Simultaneous perturbation stochastic approximation for tidal models

    KAUST Repository

    Altaf, M.U.

    2011-05-12

    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.

  12. Stingray tidal stream energy device - phase 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    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).

  13. Simultaneous perturbation stochastic approximation for tidal models

    KAUST Repository

    Altaf, M.U.; Heemink, A.W.; Verlaan, M.; Hoteit, Ibrahim

    2011-01-01

    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.

  14. Stingray tidal stream energy device - phase 3

    International Nuclear Information System (INIS)

    2005-01-01

    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)

  15. Stage-discharge relationship in tidal channels

    Science.gov (United States)

    Kearney, W. S.; Mariotti, G.; Deegan, L.; Fagherazzi, S.

    2016-12-01

    Long-term records of the flow of water through tidal channels are essential to constrain the budgets of sediments and biogeochemical compounds in salt marshes. Statistical models which relate discharge to water level allow the estimation of such records from more easily obtained records of water stage in the channel. While there is clearly structure in the stage-discharge relationship, nonlinearity and nonstationarity of the relationship complicates the construction of statistical stage-discharge models with adequate performance for discharge estimation and uncertainty quantification. Here we compare four different types of stage-discharge models, each of which is designed to capture different characteristics of the stage-discharge relationship. We estimate and validate each of these models on a two-month long time series of stage and discharge obtained with an Acoustic Doppler Current Profiler in a salt marsh channel. We find that the best performance is obtained by models which account for the nonlinear and time-varying nature of the stage-discharge relationship. Good performance can also be obtained from a simplified version of these models which approximates the fully nonlinear and time-varying models with a piecewise linear formulation.

  16. A Unified Model for Tidal Disruption Events

    Science.gov (United States)

    Dai, Lixin; McKinney, Jonathan C.; Roth, Nathaniel; Ramirez-Ruiz, Enrico; Miller, M. Coleman

    2018-06-01

    In the past few years wide-field optical and UV transient surveys and X-ray telescopes have allowed us to identify a few dozen candidate tidal disruption events (TDEs). While in theory the physical processes in TDEs are ubiquitous, a few distinct classes of TDEs have been observed. Some TDEs radiate mainly in NUV/optical, while others produce prominent X-rays. Moreover, relativistic jets have been observed in only a handful of TDEs. This diversity might be related to the details of the super-Eddington accretion and emission physics relevant to TDE disks. In this Letter, we utilize novel three-dimensional general relativistic radiation magnetohydrodynamics simulations to study the super-Eddington compact disk phase expected in TDEs. Consistent with previous studies, geometrically thick disks, wide-angle optically thick fast outflows, and relativistic jets are produced. The outflow density and velocity depend sensitively on the inclination angle, and hence so does the reprocessing of emission produced from the inner disk. We then use Monte Carlo radiative transfer to calculate the reprocessed spectra and find that that the observed ratio of optical to X-ray fluxes increases with increasing inclination angle. This naturally leads to a unified model for different classes of TDEs in which the spectral properties of the TDE depend mainly on the viewing angle of the observer with respect to the orientation of the disk.

  17. Estuary-wide genetic stock distribution and salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (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...

  18. Corium Spreading Over Concrete: The Vulcano VE-U7 and VE-U8 Tests

    International Nuclear Information System (INIS)

    Journeau, Christophe; Boccaccio, Eric; Fouquart, Pascal; Jegou, Claude; Piluso, Pascal

    2002-01-01

    Two experiments have been performed in the VULCANO facility in which prototypic corium has been spread over concrete. In the VE-U7 test, a mixture representative of what can be expected at the opening of EPR reactor-pit gate has been spread on siliceous concrete and on a reference channel in inert refractory ceramic. The spreading progression was not much affected by the presence of concrete and sparging gases. In the VE-U8 test, a UO 2 -ZrO 2 mixture, prototypic of in-vessel corium, has been spread over a lime-siliceous concrete. Although residual power was not simulated in this experiment, up to 2 cm of concrete have been eroded during the test. Results in terms of spreading behaviour, effects of gases, concrete erosion and thermal attack are presented and discussed. (authors)

  19. The Effects of the Impedance of the Flow Source on the Design of Tidal Stream Generators

    Science.gov (United States)

    Salter, S.

    2011-12-01

    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. Site condition, structure, and growth of baldcypress along tidal/non-tidal salinity gradients

    Science.gov (United States)

    Krauss, K.W.; Duberstein, J.A.; Doyle, T.W.; Conner, W.H.; Day, Richard H.; Inabinette, L.W.; Whitbeck, J.L.

    2009-01-01

    This report documents changes in forest structure and growth potential of dominant trees in salt-impacted tidal and non-tidal baldcypress wetlands of the southeastern United States. We inventoried basal area and tree height, and monitored incremental growth (in basal area) of codominant baldcypress (Taxodium distichum) trees monthly, for over four years, to examine the inter-relationships among growth, site fertility, and soil physico-chemical characteristics. We found that salinity, soil total nitrogen (TN), flood duration, and flood frequency affected forest structure and growth the greatest. While mean annual site salinity ranged from 0.1 to 3.4 ppt, sites with salinity concentrations of 1.3 ppt or greater supported a basal area of less than 40 m2/ha. Where salinity was < 0.7 ppt, basal area was as high as 87 m2/ha. Stand height was also negatively affected by higher salinity. However, salinity related only to soil TN concentrations or to the relative balance between soil TN and total phosphorus (TP), which reached a maximum concentration between 1.2 and 2.0 ppt salinity. As estuarine influence shifts inland with sea-level rise, forest growth may become more strongly linked to salinity, not only due to salt effects but also as a consequence of site nitrogen imbalance.

  1. 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)

    2007-07-15

    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

  2. EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS

    International Nuclear Information System (INIS)

    Showman, Adam P.; Polvani, Lorenzo M.

    2011-01-01

    The increasing richness of exoplanet observations has motivated a variety of three-dimensional (3D) atmospheric circulation models of these planets. Under strongly irradiated conditions, models of tidally locked, short-period planets (both hot Jupiters and terrestrial planets) tend to exhibit a circulation dominated by a fast eastward, or 'superrotating', jet stream at the equator. When the radiative and advection timescales are comparable, this phenomenon can cause the hottest regions to be displaced eastward from the substellar point by tens of degrees longitude. Such an offset has been subsequently observed on HD 189733b, supporting the possibility of equatorial jets on short-period exoplanets. Despite its relevance, however, the dynamical mechanisms responsible for generating the equatorial superrotation in such models have not been identified. Here, we show that the equatorial jet results from the interaction of the mean flow with standing Rossby waves induced by the day-night thermal forcing. The strong longitudinal variations in radiative heating-namely intense dayside heating and nightside cooling-trigger the formation of standing, planetary-scale equatorial Rossby and Kelvin waves. The Rossby waves develop phase tilts that pump eastward momentum from high latitudes to the equator, thereby inducing equatorial superrotation. We present an analytic theory demonstrating this mechanism and explore its properties in a hierarchy of one-layer (shallow-water) calculations and fully 3D models. The wave-mean-flow interaction produces an equatorial jet whose latitudinal width is comparable to that of the Rossby waves, namely the equatorial Rossby deformation radius modified by radiative and frictional effects. For conditions typical of synchronously rotating hot Jupiters, this length is comparable to a planetary radius, explaining the broad scale of the equatorial jet obtained in most hot-Jupiter models. Our theory illuminates the dependence of the equatorial jet

  3. Turist Motivasyonunda Mahalli Kültür ve Etkisi ve Apart Ziyaretlerinde Turist Memnuniyeti

    Directory of Open Access Journals (Sweden)

    Nguyen Quang VINH

    2013-09-01

    Full Text Available Bu çalışma, apart turizm hizmet sektöründe stratejik pazarlama kararının tesis edilmesi anlayışını sağlamak için turizm planlamacılarına ve turizmcilere yardım etmeyi amaçlamaktadır. Ampirik analiz için Duonglam Eski Köyü’nün apart hizmetinden faydalanmış 150 uluslararası ziyaretçinin oluşturduğu datalar kullanılmıştır. Turist motivasyonu ve nihai varış noktası sadakatindeki memnuniyet arasındaki hipotezleri test etmek amacıyla regresyon yöntemi benimsenmiştir. Bu çalışma Duonglam köyündeki iklim şartları, nihai varış noktasına ulaşım kolaylığı, konaklama kalitesi, doğal güzellikler ve hijyen şartlarının turist memnuniyeti üzerinde önemli etkileri olduğu sonucunu çıkarmıştır. Diğer taraftan da bu sonuçlar Duonglam Eski Köyü’nün kültürel aktiviteleri ve turizm hizmet sektörü hakkında olumsuz bir kanıyı temsil etmektedir. Ayrıca çalışmada, araştırmanın sınırı ve turizm sektörü çalışanları için elde edilen bulguların sonuçları tartışılmıştır.

  4. Tidal dissipation in the subsurface ocean of Enceladus

    Science.gov (United States)

    Matsuyama, I.; Hay, H.; Nimmo, F.; Kamata, S.

    2017-12-01

    Icy satellites of the outer solar system have emerged as potential habitable worlds due to the presence of subsurface oceans. As a long-term energy source, tidal heating in these oceans can influence the survivability of subsurface oceans, and the thermal, rotational, and orbital evolution of these satellites. Additionally, the spatial and temporal variation of tidal heating has implications for the interior structure and spacecraft observations. Previous models for dissipation in thin oceans are not generally applicable to icy satellites because either they ignore the presence of an overlying solid shell or use a thin shell membrane approximation. We present a new theoretical treatment for tidal dissipation in thin oceans with overlying shells of arbitrary thickness and apply it to Enceladus. The shell's resistance to ocean tides increases with shell thickness, reducing tidal dissipation as expected. Both the magnitude of energy dissipation and the resonant ocean thicknesses decrease as the overlying shell thickness increases, as previously shown using a membrane approximation. In contrast to previous work based on the traditional definition of the tidal quality factor, Q, our new definition is consistent with higher energy dissipation for smaller Q, and introduces a lower limit on Q. The dissipated power and tides are not in phase with the forcing tidal potential due to the delayed ocean response. The phase lag depends on the Rayleigh friction coefficient and ocean and shell thicknesses, which implies that phase lag observations can be used to constrain these parameters. Eccentricity heating produces higher dissipation near the poles, while obliquity heating produces higher dissipation near the equator, in contrast to the dissipation patterns in the shell. The time-averaged surface distribution of tidal heating can generate lateral shell thickness variations, providing an additional constraint on the Rayleigh friction coefficient. Explaining the endogenic power

  5. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    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.

  6. Yerelden Evrensele Japon Anime ve Manga Sanatı

    OpenAIRE

    TAŞ ALİCENAP, Çiğdem

    2014-01-01

    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...

  7. Uygulamalı Bilimler ve Mühendislik

    Directory of Open Access Journals (Sweden)

    Recep BAKIŞ

    2011-12-01

    Full Text Available Bu makalede, sanayi, tarım ve evsel atık sularla yoğun bir şekilde kirletilen Porsuk çayı ve havzasındaki yüzeysel ve yeraltı suyu kirlilik düzeyi araştırılmıştır. Bu amaçla, Porsuk çayı boyunca ve havza içinden 20 istasyon seçilerek, 2 yıl boyunca mevsimsel yüzeysel ve yeraltı su örnekleri alınmıştır. Yüzeysel sularda toplam 18, yeraltı sularında ise toplam 15 parametre analiz edilmiştir. Elde edilen sonuçlar, mevsimsel değişikliklerin sebebine bakılmaksızın, Su Kirliliği Kontrolü Yönetmeliği Kıta İçi Su Kaynakları sınıfları ve uluslar arası standartlarla karşılaştırılmıştır. Porsuk çayı ve havzasındaki hem yüzey suyunun hem de yeraltı suyunun IV. Kalite su sınıfında olduğu tespit edilmiştir

  8. On effects produced by tidal power plants upon environmental conditions in adjacent sea areas

    International Nuclear Information System (INIS)

    Nekrasov, A.V.; Romanenkov, D.A.

    1997-01-01

    Consideration is given to the change in natural (oceanographic) environmental conditions due to the transformation of the tidal oscillations structure resulting from erection and operation of tidal power plants (TPP). The relevant transformation of tidal movements encompasses practically all its main characteristics: amplitudes, phases and spectral composition of sea level oscillations, as well as the similar parameters of tidal currents and also the intensity and positioning of extremes zones. The changes in positioning and width of the inter-tidal zone, the inter-tidal zone regime, mutual arrangement of mixed, stratified and transient frontal zones, transportation of suspended matter and bottom sedimentation, owing to residual tidal currents, sea ice characteristics, air these changes can be estimated on the basis of mathematical predictive modelling of tidal characteristics transformed by a contemplated tidal power plant. Some results are presented for the Russian large-scale TPP projects in the White and Okhotsk seas. (author)

  9. Analysing how plants in coastal wetlands respond to varying tidal regimes throughout their life cycles.

    Science.gov (United States)

    Xie, Tian; Cui, Baoshan; Li, Shanze

    2017-10-15

    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.

  10. Frontal-insula gray matter deficits in first-episode medication-naïve patients with major depressive disorder.

    Science.gov (United States)

    Lai, Chien-Han; Wu, Yu-Te

    2014-05-01

    This study is designed to investigate the gray matter volume (GMV) deficits in patients with first-episode medication-naïve major depressive disorder (MDD). We enrolled 38 patients with first-episode medication-naïve MDD and 27 controls in this project. Voxel-based morphometry was used to compare GMV differences between two groups. Besides, the relationship between GMV of patients and the severity of clinical symptoms was estimated to confirm the role of GMV deficits in clinical symptoms. The correlation between total GMV and illness duration was also performed to elucidate the impacts of untreated duration on the GMV. We found that first-episode medication-naïve MDD patients had significant GMV deficits in bilateral superior frontal gyri, left middle frontal gyrus, left medial frontal gyrus and left insula. The GMV of patient group was negatively correlated with the severity of clinical symptoms and the illness duration. A pattern of GMV deficits in fronto-insula might represent the biomarker for first-episode medication-naïve MDD. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness.

    Science.gov (United States)

    Běhounková, Marie; Souček, Ondřej; Hron, Jaroslav; Čadek, Ondřej

    2017-09-01

    We investigated the effect of variations in ice shell thickness and of the tiger stripe fractures crossing Enceladus' south polar terrain on the moon's tidal deformation by performing finite element calculations in three-dimensional geometry. The combination of thinning in the polar region and the presence of faults has a synergistic effect that leads to an increase of both the displacement and stress in the south polar terrain by an order of magnitude compared to that of the traditional model with a uniform shell thickness and without faults. Assuming a simplified conductive heat transfer and neglecting the heat sources below the ice shell, we computed the global heat budget of the ice shell. For the inelastic properties of the shell described by a Maxwell viscoelastic model, we show that unrealistically low average viscosity of the order of 10 13 Pa s is necessary for preserving the volume of the ocean, suggesting the important role of the heat sources in the deep interior. Similarly, low viscosity is required to predict the observed delay of the plume activity, which hints at other delaying mechanisms than just the viscoelasticity of the ice shell. The presence of faults results in large spatial and temporal heterogeneity of geysering activity compared to the traditional models without faults. Our model contributes to understanding the physical mechanisms that control the fault activity, and it provides potentially useful information for future missions that will sample the plume for evidence of life. Key Words: Enceladus-Tidal deformation-Faults-Variable ice shell thickness-Tidal heating-Plume activity and timing. Astrobiology 17, 941-954.

  12. Analyzing Program Termination and Complexity Automatically with AProVE

    DEFF Research Database (Denmark)

    Giesl, Jürgen; Aschermann, Cornelius; Brockschmidt, Marc

    2017-01-01

    In this system description, we present the tool AProVE for automatic termination and complexity proofs of Java, C, Haskell, Prolog, and rewrite systems. In addition to classical term rewrite systems (TRSs), AProVE also supports rewrite systems containing built-in integers (int-TRSs). To analyze...... programs in high-level languages, AProVE automatically converts them to (int-)TRSs. Then, a wide range of techniques is employed to prove termination and to infer complexity bounds for the resulting rewrite systems. The generated proofs can be exported to check their correctness using automatic certifiers...

  13. Tidal dynamics in the sand motor lagoon

    NARCIS (Netherlands)

    De Vries, S.; Radermacher, M.; De Schipper, M.A.; Stive, M.J.F.

    2015-01-01

    The Sand Motor is a mega-nourishment characterized by a very large sand volume of around 20 million m3 placed along the Dutch coast. The Sand Motor is a pilot project to evaluate the performance of an alternative nourishment strategy with respect to different functions of the coastal system. Within

  14. Geometry and dynamics of a tidally deformed black hole

    International Nuclear Information System (INIS)

    Poisson, Eric; Vlasov, Igor

    2010-01-01

    The metric of a nonrotating black hole deformed by a tidal interaction is calculated and expressed as an expansion in the strength of the tidal coupling. The expansion parameter is the inverse length scale R -1 , where R is the radius of curvature of the external spacetime in which the black hole moves. The expansion begins at order R -2 , and it is carried out through order R -4 . The metric is parametrized by a number of tidal multipole moments, which specify the black hole's tidal environment. The tidal moments are freely-specifiable functions of time that are related to the Weyl tensor of the external spacetime. At order R -2 the metric involves the tidal quadrupole moments E ab and B ab . At order R -3 it involves the time derivative of the quadrupole moments and the tidal octupole moments E abc and B abc . At order R -4 the metric involves the second time derivative of the quadrupole moments, the first time derivative of the octupole moments, the tidal hexadecapole moments E abcd and B abcd , and bilinear combinations of the quadrupole moments. The metric is presented in a light-cone coordinate system that possesses a clear geometrical meaning: The advanced-time coordinate v is constant on past light cones that converge toward the black hole; the angles θ and φ are constant on the null generators of each light cone; and the radial coordinate r is an affine parameter on each generator, which decreases as the light cones converge toward the black hole. The coordinates are well-behaved on the black-hole horizon, and they are adjusted so that the coordinate description of the horizon is the same as in the Schwarzschild geometry: r=2M+O(R -5 ). At the order of accuracy maintained in this work, the horizon is a stationary null hypersurface foliated by apparent horizons; it is an isolated horizon in the sense of Ashtekar and Krishnan. As an application of our results we examine the induced geometry and dynamics of the horizon, and calculate the rate at which the

  15. Feasibility of tidal power development in the Bay of Fundy

    Energy Technology Data Exchange (ETDEWEB)

    1969-01-01

    A committee was formed to carry out technical studies on the feasibility of a tidal power plant in the Bay of Fundy. Basic information was collected on the physical, geological, climatic, and tidal characteristics of the area to determine areas for more intense investigation. Studies were conducted on the possible effects of the plant on navigation, ground transportation, fisheries, and area development. Electric power marketing and transmission were also examined, as well as the basic concepts for extracting tidal energy. A number of potential sites were examined, and the three most promising sites were selected for preliminary design and cost estimates. Computerized models were used at appropriate stages in order to evaluate various tidal power schemes. This report presents a summary of the committee's investigations. It was seen that a site at the entrance to Cobequid Bay would have an economic advantage over the other sites considered. From the results of the design studies, it was concluded that a long period of construction, plus extensive capital investment, would be required. However, the lowest unit cost of output was calculated at 5.6 mills/kWh, substantially above the incremental cost of energy available from existing sources. Under current economic conditions, the tidal power plant would not be feasible. 4 figs., 1 tab.

  16. Infrared emission and tidal interactions of spiral galaxies

    International Nuclear Information System (INIS)

    Byrd, G.G.

    1987-01-01

    Computer simulations of tidal interactions of spiral galaxies are used to attempt to understand recent discoveries about infrared (IR) emitting galaxies. It is found that the stronger tidal perturbation by a companion the more disk gas clouds are thrown into nucleus crossing orbits and the greater the velocity jumps crossing spiral arms. Both these tidally created characteristics would create more IR emission by high speed cloud collisions and more IR via effects of recently formed stars. This expectation at greater tidal perturbation matches the observation of greater IR emission for spiral galaxies with closer and/or more massive companions. The greater collision velocities found at stronger perturbations on the models will also result in higher dust temperature in the colliding clouds. In the IR pairs examined, most have only one member, the larger, detected and when both are detected, the larger is always the more luminous. In simulations and in a simple analytic description of the strong distance dependence of the tidal force, it is found that the big galaxy of a pair is more strongly affected than the small

  17. Tidal tilts observations in the Gran Sasso underground laboratory

    International Nuclear Information System (INIS)

    Iafolla, V.; Nozzoli, S.; Milyukov, V.

    2001-01-01

    A new tilt meter, based on the technology for building a space-borne high-sensitivity accelerometer and manufactured at IFSI/CNR, has a been operating during several years in the INFN Gran Sasso underground laboratory. The results of the analysis of a three-year data set, processed with the program package ETERNA, to estimate earth tidal parameters are reported. For the best series of data (1998) tide measurement accuracies are: 0.5-1% for the M 2 (lunar principal) amplitude and 3-4% for the O 1 (lunar declination) amplitude. The tilt meter installed at a depth of 1400 m shows no clear evidence of meteorological effects. Observed tidal parameters are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate good agreement for the M 2 component. Due to the high accuracy of the tidal components prediction (better than 1%) tidal measurements were used to estimate the long-term stability of the instrument response

  18. Real-time images of tidal recruitment using lung ultrasound.

    Science.gov (United States)

    Tusman, Gerardo; Acosta, Cecilia M; Nicola, Marco; Esperatti, Mariano; Bohm, Stephan H; Suarez-Sipmann, Fernando

    2015-12-01

    Ventilator-induced lung injury is a form of mechanical damage leading to a pulmonary inflammatory response related to the use of mechanical ventilation enhanced by the presence of atelectasis. One proposed mechanism of this injury is the repetitive opening and closing of collapsed alveoli and small airways within these atelectatic areas-a phenomenon called tidal recruitment. The presence of tidal recruitment is difficult to detect, even with high-resolution images of the lungs like CT scan. The purpose of this article is to give evidence of tidal recruitment by lung ultrasound. A standard lung ultrasound inspection detected lung zones of atelectasis in mechanically ventilated patients. With a linear probe placed in the intercostal oblique position. We observed tidal recruitment within atelectasis as an improvement in aeration at the end of inspiration followed by the re-collapse at the end of expiration. This mechanism disappeared after the performance of a lung recruitment maneuver. Lung ultrasound was helpful in detecting the presence of atelectasis and tidal recruitment and in confirming their resolution after a lung recruitment maneuver.

  19. Geometro-thermodynamics of tidal charged black holes

    International Nuclear Information System (INIS)

    Gergely, Laszlo Arpad; Pidokrajt, Narit; Winitzki, Sergei

    2011-01-01

    Tidal charged spherically symmetric vacuum brane black holes are characterized by their mass m and tidal charge q, an imprint of the five-dimensional Weyl curvature. For q>0 they are formally identical to the Reissner-Nordstroem black hole of general relativity. We study the thermodynamics and thermodynamic geometries of tidal charged black holes and discuss similarities and differences as compared to the Reissner-Nordstroe m black hole. As a similarity, we show that (for q>0) the heat capacity of the tidal charged black hole diverges on a set of measure zero of the parameter space, nevertheless both the regularity of the Ruppeiner metric and a Poincare stability analysis show no phase transition at those points. The thermodynamic state spaces being different indicates that the underlying statistical models could be different. We find that the q<0 parameter range, which enhances the localization of gravity on the brane, is thermodynamically preferred. Finally we constrain for the first time the possible range of the tidal charge from the thermodynamic limit on gravitational radiation efficiency at black hole mergers. (orig.)

  20. Volume and leak measurements during neonatal CPAP in neonates

    OpenAIRE

    Fischer, Hendrik S.

    2011-01-01

    As yet, little is known about the effects of air leakages during CPAP in newborns. The present doctoral dissertation investigates tidal volume and leak measurements during nasal continuous positive airway pressure in neonates using a commercial ventilatory device. Investigations include in vitro studies, modelling and computer simulation as well as a clinical randomized cross-over trial in neonates.

  1. CELESTINA: CALISTO VE MELİBEA’NIN TRAJIKOMEDYASI’NDA ORTAÇAĞ VE RÖNESANS ARASINDA KALMIŞ BİREY VE KADIN

    Directory of Open Access Journals (Sweden)

    Nur Gülümser İLKER

    2017-06-01

    Full Text Available İspanyol Edebiyatının Ortaçağ toplumu ve bireyi arasındaki çatışmayı ele almasıyla en önemli eserlerinden biri olan Celestina: Calisto ve Melibea’nın Trajikomedyası, Rönesans’a dönmüş yüzüyle de önem kazanmaktadır. Yazar Fernando de Rojas’ın ustalıkla ve incelikle yarattığı karakterler vasıtasıyla, dönemin birey algısına odaklanırken, toplumun normlarının bireyler üzerindeki üstünlüğüne tanık oluruz. Aynı zamanda kadına karşı olan bakış açısının da vurgulandığı eserde, evrensel konular gün yüzüne çıkarken, insan, doğasıyla ve içgüdüleriyle işlenerek okuyucuya sunulur. Eserde genç, tutkularının kölesi olmuş Calisto ve saf, geleneklerine bağlı Melibea’nın aşkıyla ve de yaşlı büyücü Celestina’nın tamahkârlığıyla insani duyguların aşırıya kaçması eleştirilir. Topluma uygun olmayan eylemler sonucunda cezalandırılan karakterleriyle eser, didaktik bir metin olma özelliği taşımaktadır. Çalışmanın konusu olarak sözü geçen eserdeki birey ve kadın, Ortaçağ ve Rönesans arasında kalmış olarak ele alınacak ve incelenecektir.

  2. Estimation of tidal ventilation in preterm and term newborn infants using electromagnetic inductance plethysmography

    International Nuclear Information System (INIS)

    Williams, E M; Pickerd, N; Kotecha, S; Eriksen, M; Øygarden, K

    2011-01-01

    Tidal volume (VT) measurements in newborn infants remain largely a research tool. Tidal ventilation and breathing pattern were measured using a new device, FloRight, which uses electromagnetic inductive plethysmography, and compared simultaneously with pneumotachography in 43 infants either receiving no respiratory support or continuous positive airway pressure (CPAP). Twenty-three infants were receiving CPAP (gestational age 28 ± 2 weeks, mean ± SD) and 20 were breathing spontaneously (gestational age 34 ± 4 weeks). The two methods were in reasonable agreement, with VT (r 2 = 0.69) ranging from 5 to 23 ml (4–11 ml kg −1 ) with a mean difference of 0.4 ml and limit of agreement of −4.7 to + 5.5 ml. For respiratory rate, minute ventilation, peak flow and breathing pattern indices, the mean difference between the two methods ranged between 0.7% and 5.8%. The facemask increased the respiratory rate (P < 0.001) in both groups with the change in VT being more pronounced in the infants receiving no respiratory support. Thus, FloRight provides an easy to use technique to measure term and preterm infants in the clinical environment without altering the infant's breathing pattern

  3. Differences in tidal breathing between infants with chronic lung diseases and healthy controls

    Directory of Open Access Journals (Sweden)

    Wilitzki S

    2005-09-01

    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.

  4. Assessment of the climate change impacts on fecal coliform contamination in a tidal estuarine system.

    Science.gov (United States)

    Liu, Wen-Cheng; Chan, Wen-Ting

    2015-12-01

    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.

  5. Linking human impacts within an estuary to ebb-tidal delta evolution

    Science.gov (United States)

    Dallas, Kate L.; Barnard, Patrick L.

    2009-01-01

    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.

  6. Vişne ve Nar Suyu ve Konsantratlarında Antosiyaninlerin Degradasyonu

    Directory of Open Access Journals (Sweden)

    Narmela Asafı

    2015-02-01

    Full Text Available Nar ve vişne suyu konsantratlarında antosiyaninlerin parçalanması üzerine sıcaklığın etkisi incelenmiştir. 70°Bx'lik konsantratlardan 45°Bx ve 15° Bx lik örnekler hazırlanarak -18°C, 5°C, 20°C ve 37°C depolanmıştır. Depolanma süresince, sıcaklık dercesine bağlı olarak değişik aralıklarla alman örneklerde antosiyanin kaybı saptanarak parçalanma hızı incelenmiştir. Elde edilen bulgulara göre antosiyaninlerin parçalanma­sı birinci dereceden bir reaksiyon kinetiğine göre gelişmektedir. Tüm örneklerde beklendiği gibi sıcaklık derecesi yükseldikçe antosiyaninlerin degradasyon hızları artmaktadır. Örneğin 15° Bx'lik vişne suyunda -18°C'de hız konsantı k=0.534 x 10-3 gün-1 olduğu halde, 37°C'de k= 184 x 10-3 gün-1 'e yükselmiştir. Aynı şekilde 15° Bx'lik vişne suyunda -18°C'de hız konstantı k= 0.203 x 10-3 gün-1 olduğu halde 37°C'de k= 94 x10-3 gün-1'e yükselmiştir. Ayrıca reaksiyonun sıcaklığa bağımlılığı, Arrhenius eşitliğinden yararlanarak açıklanmaya çalışılmıştır. Nar suyu ve konsantratlannda antosiyaninlerin degradasyon hızı, vişne suyu ve konsantratlarında olduğundan daha yüksektir. Böylece nar suyu ve konsantratlarında depolama süresince sıcaklığa bağlı olarak hızla renk kaybı oluşmaktadır. Ayrıca doğal briksindeki vişne suyunda antosiyaninler, konsantratlarda olduğundan daha stabil olduğu halde nar suyunda bunun aksine konsantratlardaki antosiyaninlerin daha stabil ol­duğu anlaşılmaktadır.

  7. Tanenler ve Hayvan Besleme Üzerine Etkileri

    Directory of Open Access Journals (Sweden)

    Esin Ünver

    2014-06-01

    Full Text Available Tanenler; bitkilerin yapısında doğal olarak bulunan, kendilerini patojen mikroorganizmalara ve virüslere karşı korumak için ürettikleri fenolik bileşiklerdir. Hayvan besleme açısından ise tanenler; hayvanın türü, fizyolojik durumu, tanenin yapısı ve miktarına bağlı olarak olumlu ve olumsuz etkilere sebep olabilmektedirler. Bu çalışmanın amacı; tanenler, etkileri ve hayvan beslemede kullanımları ile ilgili bir derleme sunmaktır.

  8. Feminist Sanatta Beden ve Yabancılaşma

    OpenAIRE

    Alp, Kafiye Özlem

    2015-01-01

    Feminizm, eril bir toplumda kadının, eşit hak ve özgürlüklere sahip olma gerekçelerine dayalı bir mücadele alanı olarak tanımlanabilir. Feminizmin, kamusal ve özel alanda kadın ayrımcılığına karşı başkaldırısı, insanın kendi emeğine ve kendi bedenine olan yabancılaşmasının bir sonucudur. Bu bakımdan feminizm, tüm tarihi boyunca toplumsal, felsefi, cinsel ve psikanalitik yabancılaşma kavramlarıyla yakın ilgi içinde olmuştur. Feminist sanat pratikleri; feminist kuramlar, toplumsal dinamikler...

  9. Tidal and longshore sediment transport associated to a coastal structure

    Science.gov (United States)

    Cuadrado, Diana G.; Gómez, Eduardo A.; Ginsberg, S. Susana

    2005-01-01

    In order to understand the subtidal marine dynamics relative to the coastal engineering works in the Bahía Blanca Estuary (Argentina), the balance of sediment transport caused by tidal currents was estimated in the Puerto Rosales area and compared with the predicted potential littoral transport. The breaking wave height used in the littoral drift calculation was estimated after applying different wave transforming procedures over the deepwater wave which was predicted by the occurrence of predominant wind, blowing long enough in an essentially constant direction over a fetch. The effect of a breakwater on currents and circulation was studied by bathymetric and side-scan sonar records, sedimentology, and tidal current measurements. Different modes of transport occur on either sides of the breakwater. On the east side, longshore transport is the principal mode, and on the west side, tidal transport is predominant.

  10. The gravitational self-interaction of the Earth's tidal bulge

    Science.gov (United States)

    Norsen, Travis; Dreese, Mackenzie; West, Christopher

    2017-09-01

    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.

  11. Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana

    Science.gov (United States)

    Mastalerz, Maria; Kvale, E.P.; Stankiewicz, B.A.; Portle, K.

    1999-01-01

    Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter (TOC) ranges from traces to 6.9% and sulfur rarely exceeds 0.1% in individual laminae. Angular vitrinite is the major organic matter type, accounting for 50-90% of total OM. The C/S ratio decreases as the verfical distance from the underlying coal increases. A decreasing C/S ratio coupled with decreases in Pr/Ph, Pr/n-C17, Ph/n-C18 ratios and a shift of carbon isotopic composition towards less negative values suggest an increase in salinity from freshwater in the mudflat tidal rhythmite facies close to the coal to brackish/marine in the sandflat tidal rhythmite facies further above from the coal. Within an interval spanning one year of deposition, TOC and S values show monthly variability. On a daily scale, TOC and S oscillations are still detectable but they are of lower magnitude than on a monthly scale. These small-scale variations are believed to reflect oscillations in water salinity related to tidal cycles.Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter

  12. N-Body simulations of tidal encounters between stellar systems

    International Nuclear Information System (INIS)

    Rao, P.D.; Ramamani, N.; Alladin, S.M.

    1985-10-01

    N-Body simulations have been performed to study the tidal effects of a primary stellar system on a secondary stellar system of density close to the Roche density. Two hyperbolic, one parabolic and one elliptic encounters have been simulated. The changes in energy, angular momentum, mass distribution, and shape of the secondary system have been determined in each case. The inner region containing about 40% of the mass was found to be practically unchanged and the mass exterior to the tidal radius was found to escape. The intermediate region showed tidal distension. The thickness of this region decreased as we went from hyperbolic encounters to the elliptic encounter keeping the distance of closest approach constant. The numerical results for the fractional change in energy have been compared with the predictions of the available analytic formulae and the usefulness and limitations of the formulae have been discussed. (author)

  13. The Rance tidal power plant is thirty years old

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    The 240 MW Rance tidal power plant is sited between Dinard and Saint-Malo (Brittany, France) and was inaugurated in November 26, 1966. Its availability reaches 90% and the plant has worked about 160000 hours without any major incident or failure. It has provided more than 16 TWh and it provides each year about 600 GWh to the national network. Because its functioning introduces some modifications of the natural tide conditions in the Rance estuary, EdF applies specific procedures to limit its environmental impact. The paper recalls the basic principles of the tidal power and the characteristics of the Rance plant which is the biggest in the world and which produces electric power during both the flood and the ebb. The economical aspects of the project are also described and replaced in their historical context. Other future projects of tidal plants in UK, Canada and Argentina are evoked. (J.S.)

  14. Simulations of Magnetic Fields in Tidally Disrupted Stars

    Energy Technology Data Exchange (ETDEWEB)

    Guillochon, James [Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States); McCourt, Michael, E-mail: jguillochon@cfa.harvard.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2017-01-10

    We perform the first magnetohydrodynamical simulations of tidal disruptions of stars by supermassive black holes. We consider stars with both tangled and ordered magnetic fields, for both grazing and deeply disruptive encounters. When the star survives disruption, we find its magnetic field amplifies by a factor of up to 20, but see no evidence for a self-sustaining dynamo that would yield arbitrary field growth. For stars that do not survive, and within the tidal debris streams produced in partial disruptions, we find that the component of the magnetic field parallel to the direction of stretching along the debris stream only decreases slightly with time, eventually resulting in a stream where the magnetic pressure is in equipartition with the gas. Our results suggest that the returning gas in most (if not all) stellar tidal disruptions is already highly magnetized by the time it returns to the black hole.

  15. Tidal Disruption of Phobos as the Cause of Surface Fractures

    Science.gov (United States)

    Hurford, T. A.; Asphaug, E.; Spitale, J. N.; Hemingway, D.; Rhoden, A. R.; Henning, W. G.; Bills, B. G.; Kattenhorn, S. A.; Walker, M.

    2016-01-01

    Phobos, the innermost satellite of Mars, displays an extensive system of grooves that are mostly symmetric about its sub-Mars point. Phobos is steadily spiraling inward due to the tides it raises on Mars lagging behind Phobos' orbital position and will suffer tidal disruption before colliding with Mars in a few tens of millions of years. We calculate the surface stress field of the deorbiting satellite and show that the first signs of tidal disruption are already present on its surface. Most of Phobos' prominent grooves have an excellent correlation with computed stress orientations. The model requires a weak interior that has very low rigidity on the tidal evolution time scale, overlain by an approximately 10-100 m exterior shell that has elastic properties similar to lunar regolith as described by Horvath et al. (1980).

  16. 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.

  17. Responses of water environment to tidal flat reduction in Xiangshan Bay: Part I hydrodynamics

    Science.gov (United States)

    Li, Li; Guan, Weibing; Hu, Jianyu; Cheng, Peng; Wang, Xiao Hua

    2018-06-01

    Xiangshan Bay consists of a deep tidal channel and three shallow inlets. A large-scale tidal flat has been utilized through coastal construction. To ascertain the accumulate influences of these engineering projects upon the tidal dynamics of the channel-inlets system, this study uses FVCOM to investigate the tides and flow asymmetries of the bay, and numerically simulate the long-term variations of tidal dynamics caused by the loss of tidal flats. It was found that the reduction of tidal flat areas from 1963 to 2010 slightly dampened M2 tidal amplitudes (0.1 m, ∼6%) and advanced its phases by reducing shoaling effects, while amplified M4 tidal amplitudes (0.09 m, ∼27%) and advanced its phases by reducing bottom friction, in the inner bay. Consequently, the ebb dominance was dampened indicated by reduced absolute value of elevation skewness (∼20%) in the bay. The tides and tidal asymmetry were impacted by the locations, areas and slopes of the tidal flats through changing tidal prism, shoaling effect and bottom friction, and consequently impacted tidal duration asymmetry in the bay. Tides and tidal asymmetry were more sensitive to the tidal flat at the head of the bay than the side bank. Reduced/increased tidal flat slopes around the Tie inlet dampened the ebb dominance. Tidal flat had a role in dissipating the M4 tide rather than generating it, while the advection only play a secondary role in generating the M4 tide. The full-length tidal flats reclamation would trigger the reverse of ebb to flood dominance in the bay. This study would be applicable for similar narrow bays worldwide.

  18. Characterising the spatial variability of the tidal stream energy resource from floating turbines

    Science.gov (United States)

    Ward, Sophie; Neill, Simon; Robins, Peter

    2017-04-01

    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.

  19. A numerical study of local variations in tidal regime of Tagus estuary, Portugal.

    Science.gov (United States)

    Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

    2013-01-01

    Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects.

  20. Dissociation of VE-PTP from VE-cadherin is required for leukocyte extravasation and for VEGF-induced vascular permeability in vivo

    Science.gov (United States)

    Broermann, Andre; Winderlich, Mark; Block, Helena; Frye, Maike; Rossaint, Jan; Zarbock, Alexander; Cagna, Giuseppe; Linnepe, Ruth; Schulte, Dörte; Nottebaum, Astrid Fee

    2011-01-01

    We have recently shown that vascular endothelial protein tyrosine phosphatase (VE-PTP), an endothelial membrane protein, associates with VE-cadherin and is required for optimal VE-cadherin function and endothelial cell contact integrity. The dissociation of VE-PTP from VE-cadherin is triggered by vascular endothelial growth factor (VEGF) and by the binding of leukocytes to endothelial cells in vitro, suggesting that this dissociation is a prerequisite for the destabilization of endothelial cell contacts. Here, we show that VE-cadherin/VE-PTP dissociation also occurs in vivo in response to LPS stimulation of the lung or systemic VEGF stimulation. To show that this dissociation is indeed necessary in vivo for leukocyte extravasation and VEGF-induced vascular permeability, we generated knock-in mice expressing the fusion proteins VE-cadherin-FK 506 binding protein and VE-PTP-FRB* under the control of the endogenous VE-cadherin promoter, thus replacing endogenous VE-cadherin. The additional domains in both fusion proteins allow the heterodimeric complex to be stabilized by a chemical compound (rapalog). We found that intravenous application of the rapalog strongly inhibited VEGF-induced (skin) and LPS-induced (lung) vascular permeability and inhibited neutrophil extravasation in the IL-1β inflamed cremaster and the LPS-inflamed lung. We conclude that the dissociation of VE-PTP from VE-cadherin is indeed required in vivo for the opening of endothelial cell contacts during induction of vascular permeability and leukocyte extravasation. PMID:22025303

  1. Banque Cantonale de Genève

    CERN Multimedia

    Banque Cantonale de Genève

    2011-01-01

    7e Salon Immobilier BCGE le samedi 3 septembre 2011, de 8 h 30 à 13 h 00, au Centre de formation de Conches À cette occasion, les meilleurs spécialistes professionnels genevois de l’immobilier seront réunis en un seul et même lieu. Si vous le souhaitez, un conseiller spécialisé dans les financements hypothécaires évaluera vos possibilités d’investissement immobilier adaptées à votre situation personnelle. En parallèle, les plus importantes régies immobilières de Genève seront à votre disposition pour vous présenter leurs offres actuelles, ainsi que les projets immobiliers futurs et discuter avec vous de la meilleure stratégie à adopter pour trouver l’objet de vos rêves. De plus, vous aurez la possibilité...

  2. Nonrotating black hole in a post-Newtonian tidal environment

    International Nuclear Information System (INIS)

    Taylor, Stephanne; Poisson, Eric

    2008-01-01

    We examine the motion and tidal dynamics of a nonrotating black hole placed within a post-Newtonian external spacetime. The black hole's gravity is described accurately to all orders in Gm/c 2 r, where m is the black-hole mass and r is the distance to the black hole. The tidal perturbation created by the external environment is treated as a small perturbation. At a large distance from the black hole, the gravitational field of the external distribution of matter is assumed to be sufficiently weak to be adequately described by the (first) post-Newtonian approximation to general relativity. There, the black hole is treated as a monopole contribution to the total gravitational field. There exists an overlap in the domains of validity of each description, and the black-hole and post-Newtonian metrics are matched in the overlap. The matching procedure produces (i) a justification of the statement that a nonrotating black hole is a post-Newtonian monopole; (ii) a complete characterization of the coordinate transformation between the inertial, barycentric frame and the accelerated, black-hole frame; (iii) the equations of motion for the black hole; and (iv) the gravito-electric and gravito-magnetic tidal fields acting on the black hole. We first calculate the equations of motion and tidal fields by making no assumptions regarding the nature of the post-Newtonian environment; this could contain a continuous distribution of matter (so as to model a galactic core) or any number of condensed bodies. We next specialize our discussion to a situation in which the black hole is a member of a post-Newtonian two-body system. As an application of our results, we examine the geometry of the deformed event horizon and calculate the tidal heating of the black hole, the rate at which it acquires mass as a result of its tidal interaction with the companion body.

  3. Dynamic and photometric evolutionary models of tidal tails and ripples

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1989-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broad-band photometric evolutionary code. In these models, regions of compression form inside the disk and along the tidal tail and tidal bridge. The effects these density changes have on the colors of the tidal features are examined with a broad-band photometric evolutionary code. A spiral galaxy population is synthesized and the effects of modest changes in the star formation rate are explored. Limits on the density changes needed to make detectable changes in the colors are calculated using a Schmidt (1959) law. These models suggest that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. The Lynds and Toomre (1976) interpretation of ring galaxies as the natural result of a nearly head-on collision between a disk galaxy and a companion galaxy has become widely accepted. Similarly, Quinn's (1984) interpretation of the shells in elliptical galaxies as the aftermath of the cannibalization of a low-mass companion has been quite successful in accounting for the observations. Restricted three-body calculations of high inclination, low impact parameter encounters demonstrate that the shell-like ripples observed in a number of disk galaxies can also be produced as collisional artifacts from internal oscillations much as in ring galaxies

  4. ENHANCED TIDAL DISRUPTION RATES FROM MASSIVE BLACK HOLE BINARIES

    International Nuclear Information System (INIS)

    Chen Xian; Liu, F. K.; Madau, Piero; Sesana, Alberto

    2009-01-01

    'Hard' massive black hole (MBH) binaries embedded in steep stellar cusps can shrink via three-body slingshot interactions. We show that this process will inevitably be accompanied by a burst of stellar tidal disruptions, at a rate that can be several orders of magnitude larger than that appropriate for a single MBH. Our numerical scattering experiments reveal that (1) a significant fraction of stars initially bound to the primary hole are scattered into its tidal disruption loss cone by gravitational interactions with the secondary hole, an enhancement effect that is more pronounced for very unequal mass binaries; (2) about 25% (40%) of all strongly interacting stars are tidally disrupted by an MBH binary of mass ratio q = 1/81 (q = 1/243) and eccentricity 0.1; and (3) two mechanisms dominate the fueling of the tidal disruption loss cone, a Kozai nonresonant interaction that causes the secular evolution of the stellar angular momentum in the field of the binary, and the effect of close encounters with the secondary hole that change the stellar orbital parameters in a chaotic way. For a hard MBH binary of 10 7 M sun and mass ratio 10 -2 , embedded in an isothermal stellar cusp of velocity dispersion σ * = 100 km s -1 , the tidal disruption rate can be as large as N-dot * ∼1 yr -1 . This is 4 orders of magnitude higher than estimated for a single MBH fed by two-body relaxation. When applied to the case of a putative intermediate-mass black hole inspiraling onto Sgr A*, our results predict tidal disruption rates N-dot * ∼0.05-0.1 yr -1 .

  5. The environmental interactions of tidal and wave energy generation devices

    Energy Technology Data Exchange (ETDEWEB)

    Frid, Chris, E-mail: c.l.j.frid@liv.ac.uk [School of Environmental Sciences, University of Liverpool, Crown Street, Liverpool, L69 7ZB (United Kingdom); Andonegi, Eider, E-mail: eandonegi@azti.es [AZTI-Tecnalia, Txatxarramendi ugartea, z/g E-48395 Sukarrieta (Bizkaia) (Spain); Depestele, Jochen, E-mail: jochen.depestele@ilvo.vlaanderen.be [Institute for Agricultural and Fisheries Research, Ankerstraat 1, B-8400 Oostende (Belgium); Judd, Adrian, E-mail: Adrian.Judd@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Rihan, Dominic, E-mail: Dominic.RIHAN@ec.europa.eu [Irish Sea Fisheries Board, P.O. Box 12 Dun Laoghaire, Co. Dublin (Ireland); Rogers, Stuart I., E-mail: stuart.rogers@cefas.co.uk [Centre for Environment, Fisheries and Aquaculture Science , Lowestoft Laboratory, Pakefield Road, Lowestoft NR33 0HT United Kingdom (United Kingdom); Kenchington, Ellen, E-mail: Ellen.Kenchington@dfo-mpo.gc.ca [Fisheries and Oceans Canada, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth Canada, NS B2Y 4A2 (Canada)

    2012-01-15

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: Black-Right-Pointing-Pointer We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. Black-Right-Pointing-Pointer Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. Black-Right-Pointing-Pointer Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. Black-Right-Pointing-Pointer Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  6. Breakdown of Hydrostatic Assumption in Tidal Channel with Scour Holes

    Directory of Open Access Journals (Sweden)

    Chunyan Li

    2016-10-01

    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.

  7. Effect of nasal continuous and biphasic positive airway pressure on lung volume in preterm infants

    NARCIS (Netherlands)

    Miedema, Martijn; van der Burg, Pauline S.; Beuger, Sabine; de Jongh, Frans H.; Frerichs, Inez; van Kaam, Anton H.

    2013-01-01

    To monitor regional changes in end-expiratory lung volume (EELV), tidal volumes, and their ventilation distribution during different levels of nasal continuous positive airway pressure (nCPAP) and nasal biphasic positive airway pressure (BiPAP) in stable preterm infants. By using electrical

  8. Modern sedimentary environments in a large tidal estuary, Delaware Bay

    Science.gov (United States)

    Knebel, H.J.

    1989-01-01

    Data from an extensive grid of sidescan-sonar records reveal the distribution of sedimentary environments in the large, tidally dominated Delaware Bay estuary. Bathymetric features of the estuary include large tidal channels under the relatively deep (> 10 m water depth) central part of the bay, linear sand shoals (2-8 m relief) that parallel the sides of the tidal channels, and broad, low-relief plains that form the shallow bay margins. The two sedimentary environments that were identified are characterized by either (1) bedload transport and/or erosion or (2) sediment reworking and/or deposition. Sand waves and sand ribbons, composed of medium to coarse sands, define sites of active bedload transport within the tidal channels and in gaps between the linear shoals. The sand waves have spacings that vary from 1 to 70 m, amplitudes of 2 m or less, and crestlines that are usually straight. The orientations of the sand waves and ribbons indicate that bottom sediment movement may be toward either the northwest or southeast along the trends of the tidal channels, although sand-wave asymmetry indicates that the net bottom transport is directed northwestward toward the head of the bay. Gravelly, coarse-grained sediments, which appear as strongly reflective patterns on the sonographs, are also present along the axes and flanks of the tidal channels. These coarse sediments are lag deposits that have developed primarily where older strata were eroded at the bay floor. Conversely, fine sands that compose the linear shoals and muddy sands that cover the shallow bay margins appear mainly on the sonographs either as smooth featureless beds that have uniform light to moderate shading or as mosaics of light and dark patches produced by variations in grain size. These acoustic and textural characteristics are the result of sediment deposition and reworking. Data from this study (1) support the hypothesis that bed configurations under deep tidal flows are functions of current

  9. Bedform evolution in a tidal inlet referred from wavelet analysis

    DEFF Research Database (Denmark)

    Fraccascia, Serena; Winter, Christian; Ernstsen, Verner Brandbyge

    2011-01-01

    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...... inlet and evaluate how they changed over consecutive years, when morphology was modified and bedforms migrated. High resolution bathymetric data from the Grådyb tidal inlet channel (Danish Wadden Sea) from seven years from 2002 to 2009 (not in 2004) were analyzed. Continuous wavelet transform of bed...

  10. Environmental impact assessment of Kachchh tidal power project

    International Nuclear Information System (INIS)

    Yadav, Ramanand; Lal, B.B.

    1995-01-01

    The Kachchh tidal power development project is a single-basin, single -effect and ebb generation development by construction of a tidal power barrage of about 3.25 km length across Hansthal creek. The project may disturb the ecosystem of the region. The paper deals in detail the environmental impacts of the project on climate, water velocity, flow and sedimentation pattern, water quality, flora and fauna, fishery, tourism and recreation, wild life, public health and socio-economic conditions. (author). 4 refs., 1 fig., 2 tabs

  11. Observations of the Ushant tidal front in September 2007

    OpenAIRE

    Le Boyer, A.; Cambon, Gildas; Daniault, N.; Herbette, Steven; Le Cann, B.; Marie, Louis; Morin, P.

    2009-01-01

    The Ushant tidal front is the dominant feature of the summer season hydrological structure of the Iroise Sea. It separates tidally mixed coastal waters from thermally stratified open Celtic Sea waters. This article reports on observations made in September 2007 during two short cruises that took place aboard R/V "Cotes de la Manche", and gives a general account of the physical structure of the front along one cross-frontal transect. The data set comprises data from a 4 month ADCP mooring, sho...

  12. Research on Local Scour at Bridge Pier under Tidal Action

    Directory of Open Access Journals (Sweden)

    Wang Jianping

    2015-01-01

    Full Text Available Through the local scour test at bridge pier under tidal action in a long time series, this paper observes the growing trend of the deepest point of local scour at bridge pier under tidal conditions with different characteristic parameters, analyzes the impact of repeat sediment erosion and deposition in the scouring pit caused by reversing current on the development process of the scouring pit, and clarifies the relation between the tide and local scouring depth at bridge pier under steady flow conditions, so as to provide a scientific basis for bridge design and safe operation of estuary and harbor areas.

  13. Periodicity in stem growth and litterfall in tidal freshwater forested wetlands: influence of salinity and drought on nitrogen recycling

    Science.gov (United States)

    Cormier, Nicole; Krauss, Ken W.; Conner, William H.

    2013-01-01

    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

  14. Tom Stoppard'ın Rosencrantz ve Guildenstern Öldüler Adlı Oyununda Mizah ve Kader

    OpenAIRE

    Erkan, Ayça Ülker

    2016-01-01

    Bu çalışmanın amacı karakterlerin kimlik arayışından kaynaklanan fiziksel mizahı tartışmak ve oyundaki ölüm/şans/kader/gerçeklik/yanılsama gibi temaların Rosencrantz ve Guildenstern’nin varoluşçu hayatlarında nasıl işlediğini göstermektir. Mizah, bu trajikomedinin analiz edilmesinde önemli bir rol oynar. Absürd Tiyatro, insanlık durumundaki saçmalığı ifade eder, rasyonel aygıtların kullanımını terk eder, insanın trajik kaybolmuşluk duygusunu yansıtır ve insanlık durumu olan hayat ve ölümle il...

  15. 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.

    2000-01-01

    Air-borne and satellite based altimetry are used to monitor the Greenland ice-cap. Since these measurements are related to fiducial sites at the coast, the robustness of the height differences depends on the stability of these reference points. To benefit from the accuracy of these methods...... on the centimeter level, station corrections regarding the Earth tides and the ocean tidal loading have to be applied. Models for global corrections esp. for the body tides are available and sufficient, but local corrections regarding the effect of the adjacent shelf area still have to be inferred from additional...... 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...

  16. Tidal extension and sea-level rise: recommendations for a research agenda

    Science.gov (United States)

    Ensign, Scott H.; Noe, Gregory

    2018-01-01

    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.

  17. 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...

  18. Adélie penguin foraging location predicted by tidal regime switching.

    Science.gov (United States)

    Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

    2013-01-01

    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.

  19. 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)

    2011-06-29

    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.

  20. The Power Coefficient in the Theory of Energy Extraction from Tidal Channels

    Science.gov (United States)

    Cummins, P. F.

    2014-12-01

    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.