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Sample records for arterial-end tidal carbon

  1. [Correlation between end-tidal carbon dioxide and partial pressure of arterial carbon dioxide in ventilated newborns].

    Science.gov (United States)

    Feng, Jin-Xing; Liu, Xiao-Hong; Huang, Hui-Jun; Yu, Zhen-Zhu; Yang, Hui; He, Liu-Fang

    2014-05-01

    To study the correlation between end-tidal carbon dioxide (PetCO2) and partial pressure of arterial carbon dioxide (PaCO2) in ventilated newborns. Thirty-one ventilated newborn underwent mainstream PetCO2 monitoring; meanwhile, arterial blood gas analysis was performed. The correlation and consistency between PetCO2 and PaCO2 were assessed. A total of 85 end-tidal and arterial CO2 pairs were obtained from 31 ventilated newborns. The mean PetCO2 (41±10 mm Hg) was significantly lower than the corresponding mean PaCO2 (46±11 mm Hg) (Plimits of consistency, -3.3 to 13.6 mmHg), and 5% (4/85) of the points were beyond the 95%CI. When the oxygenation index (OI) was less than 300 mm Hg (n=48), there was a significant positive correlation between PetCO2 and PaCO2 (r=0.85, Plimits of consistency, -2.6 to 14.5 mm Hg), and 4.2% (2/48) of the points were beyond the 95%CI. When the OI was more than 300 mm Hg (n=37), there was also a significant positive correlation between PetCO2 and PaCO2 (r=0.91, Plimits of consistency, -3.9 to 12.1 mm Hg), and 5% (2/37) of the points were beyond the 95%CI. There is a good correlation and consistency between PetCO2 and PaCO2 in ventilated newborns.

  2. Mainstream end-tidal carbon dioxide monitoring in the neonatal intensive care unit.

    Science.gov (United States)

    Rozycki, H J; Sysyn, G D; Marshall, M K; Malloy, R; Wiswell, T E

    1998-04-01

    Continuous noninvasive monitoring of arterial carbon dioxide (CO2) in neonatal intensive care unit (NICU) patients would help clinicians avoid complications of hypocarbia and hypercarbia. End-tidal CO2 monitoring has not been used in this population to date, but recent technical advances and the introduction of surfactant therapy, which improves ventilation-perfusion matching, might improve the clinical utility of end-tidal monitoring. To determine the accuracy and precision of end-tidal CO2 monitoring in NICU patients. Nonrandomized recording of simultaneous end-tidal and arterial CO2 pairs. Two university NICUs. Forty-five newborn infants receiving mechanical ventilation who had indwelling arterial access, and a predefined subsample of infants who were NICU patients is as accurate as capillary or transcutaneous monitoring but less precise than the latter. It may be useful for trending or for screening patients for abnormal arterial CO2 values.

  3. Anaesthesia for laparoscopic nephrectomy: Does end-tidal carbon dioxide measurement correlate with arterial carbon dioxide measurement?

    Science.gov (United States)

    Jayan, Nithin; Jacob, Jaya Susan; Mathew, Mohan

    2018-04-01

    Not many studies have explored the correlation between arterial carbon dioxide tension (PaCO 2 ) and end-tidal carbon dioxide tension (ETCO 2 ) in surgeries requiring pneumoperitoneum of more than 1 hour duration with the patient in non-supine position. The aim of our study was to evaluate the correlation of ETCO 2 with PaCO 2 in patients undergoing laparoscopic nephrectomy under general anaesthesia. A descriptive study was performed in thirty patients undergoing laparoscopic nephrectomy from September 2014 to August 2015. The haemodynamic parameters, minute ventilation, PaCO 2 and ETCO 2 measured at three predetermined points during the procedure were analysed. Correlation was checked using Pearson's Correlation Coefficient Test. P <0.05 was considered statistically significant. Statistical analysis of the values showed a positive correlation between ETCO 2 and PaCO 2 ( P < 0.05). Following carbon dioxide insufflation, both ETCO 2 and PaCO 2 increased by 5.4 and 6.63 mmHg, respectively, at the end of the 1 st hour. The PaCO 2 -ETCO 2 gradient was found to increase during the 1 st hour following insufflation (4.07 ± 2.05 mmHg); it returned to the pre-insufflation values in another hour (2.93 ± 1.43 mmHg). Continuous ETCO 2 monitoring is a reliable indicator of the trend in arterial CO 2 fluctuations in the American Society of Anesthesiologists Grades 1 and 2 patients undergoing laparoscopic nephrectomy under general anaesthesia.

  4. End-tidal carbon dioxide monitoring during flexible fiberoptic ...

    African Journals Online (AJOL)

    Arterial oxygen saturation is usually monitored with pulse oximetry Spo2) during FFB; END-TIDAL Pco2) (ET-Pco2) monitoring is not routinely used. Two-hundred patients were studied between May 1998 till April 2003, at the divisions of chest surgery and pulmonolgy at King Hussein Medical Center, (khmc). Their ages ...

  5. Increased requirement for minute ventilation and negative arterial to end-tidal carbon dioxide gradient may indicate malignant hyperthermia

    Directory of Open Access Journals (Sweden)

    Ho-Tien Lin

    2014-04-01

    Full Text Available Characteristic signs of malignant hyperthermia (MH include unexplained tachycardia, increased end-tidal carbon dioxide (Etco2 concentration, metabolic and respiratory acidosis, and an increase in body temperature above 38.8°C. We present the case of a patient with highly probable MH. In addition to sinus tachycardia and metabolic and respiratory acidosis, this patient also had a negative arterial to Etco2 gradient and an increased requirement for minute ventilation to maintain a normal Etco2 concentration, with signs of increased CO2 production. Despite these signs of MH, the patient's rectal temperature monitoring equipment did not show an increase in temperature, although the temperature measured in the mouth was increased. This case illustrates the unreliability of measuring rectal temperature as a means of reflecting body temperature during MH and the usefulness of increased CO2 production signs in helping to diagnose MH.

  6. End-inspiratory rebreathing reduces the end-tidal to arterial PCO2 gradient in mechanically ventilated pigs

    NARCIS (Netherlands)

    Fierstra, Jorn; Machina, Matthew; Battisti-Charbonney, Anne; Duffin, James; Fisher, Joseph Arnold; Minkovich, Leonid

    Noninvasive monitoring of the arterial partial pressures of CO2 (PaCO2) of critically ill patients by measuring their end-tidal partial pressures of CO2 (PetCO(2)) would be of great clinical value. However, the gradient between PetCO(2) and PaCO2 (Pet-aCO(2)) in such patients typically varies over a

  7. Transient influence of end-tidal carbon dioxide tension on the postural restraint in cerebral perfusion

    DEFF Research Database (Denmark)

    Immink, R.V.; Truijen, J.; Secher, Niels H.

    2009-01-01

    In the upright position, cerebral blood flow is reduced, maybe because arterial carbon dioxide partial pressure (Pa(CO(2))) decreases. We evaluated the time-dependent influence of a reduction in Pa(CO(2)), as indicated by the end-tidal Pco(2) tension (Pet(CO(2))), on cerebral perfusion during head......-up tilt. Mean arterial pressure, cardiac output, middle cerebral artery mean flow velocity (MCA V(mean)), and dynamic cerebral autoregulation at supine rest and 70 degrees head-up tilt were determined during free breathing and with Pet(CO(2)) clamped to the supine level. The postural changes in central...... hemodynamic variables were equivalent, and the cerebrovascular autoregulatory capacity was not significantly affected by tilt or by clamping Pet(CO(2)). In the first minute of tilt, the decline in MCA V(mean) (10 +/- 4 vs. 3 +/- 4 cm/s; mean +/- SE; P

  8. End tidal-to-arterial CO2 and O2 gas gradients at low- and high-altitude during dynamic end-tidal forcing.

    Science.gov (United States)

    Tymko, Michael M; Ainslie, Philip N; MacLeod, David B; Willie, Chris K; Foster, Glen E

    2015-06-01

    We sought to characterize and quantify the performance of a portable dynamic end-tidal forcing (DEF) system in controlling the partial pressure of arterial CO2 (Pa(CO2)) and O2 (Pa(O2)) at low (LA; 344 m) and high altitude (HA; 5,050 m) during an isooxic CO2 test and an isocapnic O2 test, which is commonly used to measure ventilatory and vascular reactivity in humans (n = 9). The isooxic CO2 tests involved step changes in the partial pressure of end-tidal CO2 (PET(CO2)) of -10, -5, 0, +5, and +10 mmHg from baseline. The isocapnic O2 test consisted of a 10-min hypoxic step (PET(O2) = 47 mmHg) from baseline at LA and a 5-min euoxic step (PET(O2) = 100 mmHg) from baseline at HA. At both altitudes, PET(O2) and PET(CO2) were controlled within narrow limits (<1 mmHg from target) during each protocol. During the isooxic CO2 test at LA, PET(CO2) consistently overestimated Pa(CO2) (P < 0.01) at both baseline (2.1 ± 0.5 mmHg) and hypercapnia (+5 mmHg: 2.1 ± 0.7 mmHg; +10 mmHg: 1.9 ± 0.5 mmHg). This P(a)-PET(CO2) gradient was approximately twofold greater at HA (P < 0.05). At baseline at both altitudes, PET(O2) overestimated Pa(O2) by a similar extent (LA: 6.9 ± 2.1 mmHg; HA: 4.5 ± 0.9 mmHg; both P < 0.001). This overestimation persisted during isocapnic hypoxia at LA (6.9 ± 0.6 mmHg) and during isocapnic euoxia at HA (3.8 ± 1.2 mmHg). Step-wise multiple regression analysis, on the basis of the collected data, revealed that it may be possible to predict an individual's arterial blood gases during DEF. Future research is needed to validate these prediction algorithms and determine the implications of end-tidal-to-arterial gradients in the assessment of ventilatory and/or vascular reactivity. Copyright © 2015 the American Physiological Society.

  9. Evaluation of a transportable capnometer for monitoring end-tidal carbon dioxide

    DEFF Research Database (Denmark)

    Hildebrandt, T; Tobiasen, Malene Espelund; Olsen, K S

    2010-01-01

    We compared a small and transportable Capnometer (EMMA™) with a reference capnometer, the Siesta i TS Anaesthesia. During air-breathing through a facemask, both the EMMA (nine modules) and reference capnometer sampled expired gas simultaneously. A wide range of end-tidal carbon dioxide values were...... obtained during inhalation of carbon dioxide and voluntary hyperventilation. The median IQR [range] difference between all sets of carbon dioxide values (EMMA - reference) was -0.3 (-0.6 to 0.0 [-1.7 to 1.6] kPa; n = 297) using new batteries, which was statistically significant (p = 0.04) and located...... to two of the nine EMMAs tested. Using batteries with reduced voltage did not influence the measurements. The 95% CI of the medians of the differences were -0.4 to -0.2. We conclude that the EMMA can slightly under-read the end-tidal carbon dioxide but is generally comparable with a free-standing monitor...

  10. 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.

  11. Appropriate xenon-inhalation speed in xenon-enhanced CT using the end-tidal gas-sampling method

    International Nuclear Information System (INIS)

    Suga, Sadao; Toya, Shigeo; Kawase, Takeshi; Koyama, Hideki; Shiga, Hayao

    1986-01-01

    This report describes some problems when end-tidal xenon gas is substituted for the arterial xenon concentration in xenon-enhanced CT. The authors used a newly developed xenon inhalator with a xenon-gas-concentration analyzer and performed xenon-enhanced CT by means of the ''arterio-venous shunt'' method and the ''end-tidal gas-sampling'' method simultaneously. By the former method, the arterial build-up rate (K) was obtained directly from the CT slices of a blood circuit passing through the phantom. By the latter method, it was calculated from the xenon concentration of end-tidal gas sampled from the mask. The speed of xenon supply was varied between 0.6 - 1.2 L/min. in 11 patients with or without a cerebral lesion. The results revealed that rapid xenon inhalation caused a discrepancy in the arterial K between the ''shunt'' method and the ''end-tidal'' method. This discrepancy may be responsible for the mixing of inhalated gas and expired gas in respiratory dead space, such as the nasal cavity or the mask. The cerebral blood flow was underestimated because of the higher arterial K in the latter method. Too much slow inhalation, however, was timewasting, and it increased the body motion in the subanesthetic state. Therefore, an inhalation speed of the arterial K of as much as 0.2 was ideal to represent the end-tidal xenon concentration for the arterial K in the ''end-tidal gas-sampling'' method. When attention is given to this point, this method may offer a reliable absolute value in xenon-enhanced CT. (author)

  12. Data supporting the use of end-tidal carbon dioxide (ETCO2 measurement to guide management of cardiac arrest: A systematic review

    Directory of Open Access Journals (Sweden)

    Edison F. Paiva

    2018-06-01

    Full Text Available The data presented in this article are related to the research article, “The Use of End-Tidal Carbon Dioxide (ETCO2 Measurement to Guide Management of Cardiac Arrest: A Systematic Review” [1]. This article is a systematic review and meta-analysis of existing data on the subject of whether any level of end-tidal carbon dioxide (ETCO2 measured during cardiopulmonary resuscitation (CPR correlates with return of spontaneous circulation (ROSC or survival in adult patients experiencing cardiac arrest in any setting. These data are made publicly available to enable critical or extended analyses. Keywords: Cardiac arrest, End tidal carbon dioxide, Prognostication, Advanced cardiac life support, Capnography, Systematic review, Meta-analysis

  13. Application of end-tidal carbon dioxide monitoring via distal gas samples in ventilated neonates.

    Science.gov (United States)

    Jin, Ziying; Yang, Maoying; Lin, Ru; Huang, Wenfang; Wang, Jiangmei; Hu, Zhiyong; Shu, Qiang

    2017-08-01

    Previous research has suggested correlations between the end-tidal partial pressure of carbon dioxide (P ET CO 2 ) and the partial pressure of arterial carbon dioxide (PaCO 2 ) in mechanically ventilated patients, but both the relationship between P ET CO 2 and PaCO 2 and whether P ET CO 2 accurately reflects PaCO 2 in neonates and infants are still controversial. This study evaluated remote sampling of P ET CO 2 via an epidural catheter within an endotracheal tube to determine the procedure's clinical safety and efficacy in the perioperative management of neonates. Abdominal surgery was performed under general anesthesia in 86 full-term newborns (age 1-30 days, weight 2.55-4.0 kg, American Society of Anesthesiologists class I or II). The infants were divided into 2 groups (n = 43 each), and carbon dioxide (CO 2 ) gas samples were collected either from the conventional position (the proximal end) or a modified position (the distal end) of the epidural catheter. The P ET CO 2 measured with the new method was significantly higher than that measured with the traditional method, and the difference between P ET CO 2 and PaCO 2 was also reduced. The accuracy of P ET CO 2 measured increased from 78.7% to 91.5% when the modified sampling method was used. The moderate correlation between P ET CO 2 and PaCO 2 by traditional measurement was 0.596, which significantly increased to 0.960 in the modified sampling group. Thus, the P ET CO 2 value was closer to that of PaCO 2 . P ET CO 2 detected via modified carbon dioxide monitoring had a better accuracy and correlation with PaCO 2 in neonates. Copyright © 2017. Published by Elsevier B.V.

  14. Arterial to end-tidal carbon dioxide tension difference (CO2 gap) as a prognostic marker for adverse outcomes in emergency department patients presenting with suspected sepsis.

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    Shetty, Amith; Sparenberg, Sebastian; Adams, Kristian; Selvedran, Selwyn; Tang, Benjamin; Hanna, Kim; Iredell, Jonathan

    2018-05-13

    The arterial to end-tidal carbon dioxide tension difference (CO 2 gap) correlates with physiologic dead space. The prognostic value of increased CO 2 gap in trauma and respiratory distress patients is documented. Transpulmonary arteriovenous shunting is identified as a predictor of mortality in non-pulmonary sepsis. We set out to investigate the prognostic value of the CO 2 gap in a pilot study of patients with suspected sepsis from non-respiratory causes. Patients presenting to tertiary Australian ED with suspected sepsis (n = 215) underwent near-simultaneous end-tidal carbon dioxide and partial pressure of carbon dioxide measurements. We investigated the correlation of CO 2 gap levels with the primary outcome of in-hospital mortality (IHM) and secondary outcomes of sepsis (ΔSOFA ≥2) and IHM and/or intensive care unit stay ≥72 h (IHM/ICU72h) in patients with sepsis because of non-respiratory causes. Among patients included in the analysis (n = 165), the CO 2 gap showed modest positive correlation with qSOFA (ρ = 0.39) and weak positive correlation with SOFA scores (ρ = 0.29) (both P < 0.01). The CO 2 gap had modest predictive value for primary outcome (IHM), area under receiver operating curve (AUROC 0.85, 95% confidence interval [CI] 0.78-0.90) and IHM/ICU72h outcome (AUROC 0.80, 95% CI 0.73-0.86), but lower predictive value for sepsis outcome (AUROC 0.64, 95% CI 0.55-0.71) (all P < 0.001). We report modest test performance for primary outcome at CO 2 gap ≥5 and ≥10 mmHg cut-offs. In this pilot study of patients with suspected sepsis from non-respiratory causes, an increased CO 2 gap demonstrates value in risk stratification and needs to be further evaluated and compared to other existent biomarkers. © 2018 Australasian College for Emergency Medicine & Australasian Society for Emergency Medicine.

  15. End-tidal carbon dioxide (ETCO2) can replace methods for measuring partial pressure of carbon dioxide (PCO2) in pigs

    DEFF Research Database (Denmark)

    Alstrup, Aage Kristian Olsen

    2017-01-01

    We compared end-tidal carbon dioxide (ETCO2) with partial pressure of carbon dioxide (PCO2) in domestic pigs anesthetized for neuroscience. There was good agreement between ETCO2 and PCO2 under both hypocapnia, normocapnia, and hypercapnia conditions. ETCO2 saves time by continually providing...

  16. Assessing Dehydration Employing End-Tidal Carbon Dioxide in Children With Vomiting and Diarrhea.

    Science.gov (United States)

    Freedman, Stephen B; Johnson, David W; Nettel-Aguirre, Alberto; Mikrogianakis, Angelo; Williamson-Urquhart, Sarah; Monfries, Nicholas; Cheng, Adam

    2017-05-23

    Serum bicarbonate reflects dehydration severity in children with gastroenteritis. Previous work in children receiving intravenous rehydration has correlated end-tidal carbon dioxide (EtCO2) with serum bicarbonate. We evaluated whether EtCO2 predicts weight change in children with vomiting and/or diarrhea. A prospective cohort study was conducted. Eligible children were 3 months to 10 years old and presented for emergency department (ED) care because of vomiting and/or diarrhea. End-tidal carbon dioxide measurements were performed after triage. The diagnostic standard was weight change determined from serial measurements after symptom resolution. A receiver operating characteristic curve was constructed to identify a cut-point to predict 5% or more dehydration. In total, 195 children were enrolled. Among the 169 (87%) with EtCO2 measurements, the median (interquartile range [IQR]) was 30.4 (27.8 to 33.1). One hundred fifty-eight had repeat weights performed at home; the median (IQR) weight change from ED presentation to well weight was +0.06 (-0.14 to +0.30) or +0.72% (-1.2% to +2.1%). Sixteen percent (25/158) had 3% or more and 4% (6/158) had 5% or more weight gain (ie, percent dehydration). One hundred sixteen (60%) completed home follow-up and had acceptable EtCO2 recordings. Receiver operating curve analysis revealed an area under the curve of 0.34 (95% confidence interval, 0.06 to 0.62) for EtCO2 as a predictor of 5% or more dehydration. The limited accuracy of EtCO2 measurement to predict 5% or more dehydration precludes its use as a tool to assess dehydration severity in children. End-tidal carbon dioxide monitoring does not have the ability to identify those children with 5% or more dehydration in a cohort of children with vomiting and/or diarrhea presenting for ED care.

  17. Effect of one-lung ventilation on end-tidal carbon dioxide during cardiopulmonary resuscitation in a pig model of cardiac arrest.

    Science.gov (United States)

    Ryu, Dong Hyun; Jung, Yong Hun; Jeung, Kyung Woon; Lee, Byung Kook; Jeong, Young Won; Yun, Jong Geun; Lee, Dong Hun; Lee, Sung Min; Heo, Tag; Min, Yong Il

    2018-01-01

    Unrecognized endobronchial intubation frequently occurs after emergency intubation. However, no study has evaluated the effect of one-lung ventilation on end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). We compared the hemodynamic parameters, blood gases, and ETCO2 during one-lung ventilation with those during conventional two-lung ventilation in a pig model of CPR, to determine the effect of the former on ETCO2. A randomized crossover study was conducted in 12 pigs intubated with double-lumen endobronchial tube to achieve lung separation. During CPR, the animals underwent three 5-min ventilation trials based on a randomized crossover design: left-lung, right-lung, or two-lung ventilation. Arterial blood gases were measured at the end of each ventilation trial. Ventilation was provided using the same tidal volume throughout the ventilation trials. Comparison using generalized linear mixed model revealed no significant group effects with respect to aortic pressure, coronary perfusion pressure, and carotid blood flow; however, significant group effect in terms of ETCO2 was found (P < 0.001). In the post hoc analyses, ETCO2 was lower during the right-lung ventilation than during the two-lung (P = 0.006) or left-lung ventilation (P < 0.001). However, no difference in ETCO2 was detected between the left-lung and two-lung ventilations. The partial pressure of arterial carbon dioxide (PaCO2), partial pressure of arterial oxygen (PaO2), and oxygen saturation (SaO2) differed among the three types of ventilation (P = 0.003, P = 0.001, and P = 0.001, respectively). The post hoc analyses revealed a higher PaCO2, lower PaO2, and lower SaO2 during right-lung ventilation than during two-lung or left-lung ventilation. However, the levels of these blood gases did not differ between the left-lung and two-lung ventilations. In a pig model of CPR, ETCO2 was significantly lower during right-lung ventilation than during two-lung ventilation. However

  18. Effects of sodium bicarbonate on the end-tidal CO2, PaCO2, HCO3-, PH and cerebral blood flow

    International Nuclear Information System (INIS)

    Komatani, Akio; Akutsu, Tooru; Yoshida, Michihiko; Yamaguchi, Koichi; Seo, Hiroshi

    1992-01-01

    To estimate the quantitative reactivity of cerebral blood flow (CBF), the effects of sodium bicarbonate on the end-tidal CO 2 , arterial partial pressure of CO 2 (PaCO 2 ), HCO 3 - , pH and CBF were examined. The CBF was measured by 133 Xe inhalation method with ring type SPECT (HEADTOME). Activation study with sodium bicarbonate administration was performed after 30 minutes of resting study, and the reactivity of each parameters was investigated. The arterial HCO 3 - and pH increased with similar reactivity, but PaCO 2 , end-tidal CO 2 and CBF in the non-injured hemisphere changed with irregular reactivity. The excellent correlation between PaCO 2 and end-tidal CO 2 was vanished by the administration of sodium bicarbonate. The reactivity of CBF did not correlate with reactivity of PaCO 2 and end-tidal CO 2 , but correlated with arterial HCO 3 - and pH. Thus the measurement of arterial HCO 3 - and pH may be indispensable to estimate the CBF reactivity with the administration of sodium bicarbonate. (author)

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

    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.

  20. 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.

  1. Effects of sodium bicarbonate on the end-tidal CO[sub 2], PaCO[sub 2], HCO[sub 3][sup -], PH and cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Komatani, Akio; Akutsu, Tooru; Yoshida, Michihiko; Yamaguchi, Koichi; Seo, Hiroshi (Yamagata Univ. (Japan). School of Medicine)

    1992-09-01

    To estimate the quantitative reactivity of cerebral blood flow (CBF), the effects of sodium bicarbonate on the end-tidal CO[sub 2], arterial partial pressure of CO[sub 2] (PaCO[sub 2]), HCO[sub 3][sup -], pH and CBF were examined. The CBF was measured by [sup 133]Xe inhalation method with ring type SPECT (HEADTOME). Activation study with sodium bicarbonate administration was performed after 30 minutes of resting study, and the reactivity of each parameters was investigated. The arterial HCO[sub 3][sup -] and pH increased with similar reactivity, but PaCO[sub 2], end-tidal CO[sub 2] and CBF in the non-injured hemisphere changed with irregular reactivity. The excellent correlation between PaCO[sub 2] and end-tidal CO[sub 2] was vanished by the administration of sodium bicarbonate. The reactivity of CBF did not correlate with reactivity of PaCO[sub 2] and end-tidal CO[sub 2], but correlated with arterial HCO[sub 3][sup -] and pH. Thus the measurement of arterial HCO[sub 3][sup -] and pH may be indispensable to estimate the CBF reactivity with the administration of sodium bicarbonate. (author).

  2. The effect of two different intra-operative end-tidal carbon dioxide tensions on apnoeic duration in the recovery period in horses.

    Science.gov (United States)

    Thompson, Kate R; Bardell, David

    2016-03-01

    To compare the effect of two different intraoperative end-tidal carbon dioxide tensions on apnoeic duration in the recovery period in horses. Prospective randomized clinical study. Eighteen healthy client-owned adult horses (ASA I-II) admitted for elective surgery. Horses were of a median body mass of 595 (238-706) kg and a mean age of 9 ± 5 years. A standardized anaesthetic protocol was used. Horses were positioned in dorsal recumbency and randomly allocated to one of two groups. Controlled mechanical ventilation (CMV) was adjusted to maintain the end-tidal carbon dioxide tension (Pe'CO2 ) at 40 ± 5 mmHg (5.3 ± 0.7 kPa) (group 40) or 60 ± 5 mmHg (8.0 ± 0.7 kPa) (group 60). Arterial blood gas analysis was performed at the start of the anaesthetic period (T0), at one point during the anaesthetic (T1), immediately prior to disconnection from the breathing system (T2) and at the first spontaneous breath in the recovery box (T3). The time from disconnection from the breathing system to return to spontaneous ventilation (RSV) was recorded. Data were analysed using a two sample t-test or the Mann-Whitney U-test and significance assigned when p breathing significantly earlier than those in group 40, [52 (14-151) and 210 (103-542) seconds, respectively] (p tension (PaO2 ), pH, base excess (BE) and plasma bicarbonate (HCO3-) were not different between the groups at RSV, however, PaO2 was significantly lower in group 60 during (T1) and at the end of anaesthesia (T2). Aiming to maintain intra-operative Pe'CO2 at 60 ± 5 mmHg (8.0 ± 0.7 kPa) in mechanically ventilated horses resulted in more rapid RSV compared with when Pe'CO2 was maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa). © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  3. End-Tidal CO2-Guided Chest Compression Delivery Improves Survival in a Neonatal Asphyxial Cardiac Arrest Model.

    Science.gov (United States)

    Hamrick, Justin T; Hamrick, Jennifer L; Bhalala, Utpal; Armstrong, Jillian S; Lee, Jeong-Hoo; Kulikowicz, Ewa; Lee, Jennifer K; Kudchadkar, Sapna R; Koehler, Raymond C; Hunt, Elizabeth A; Shaffner, Donald H

    2017-11-01

    To determine whether end-tidal CO2-guided chest compression delivery improves survival over standard cardiopulmonary resuscitation after prolonged asphyxial arrest. Preclinical randomized controlled study. University animal research laboratory. 1-2-week-old swine. After undergoing a 20-minute asphyxial arrest, animals received either standard or end-tidal CO2-guided cardiopulmonary resuscitation. In the standard group, chest compression delivery was optimized by video and verbal feedback to maintain the rate, depth, and release within published guidelines. In the end-tidal CO2-guided group, chest compression rate and depth were adjusted to obtain a maximal end-tidal CO2 level without other feedback. Cardiopulmonary resuscitation included 10 minutes of basic life support followed by advanced life support for 10 minutes or until return of spontaneous circulation. Mean end-tidal CO2 at 10 minutes of cardiopulmonary resuscitation was 34 ± 8 torr in the end-tidal CO2 group (n = 14) and 19 ± 9 torr in the standard group (n = 14; p = 0.0001). The return of spontaneous circulation rate was 7 of 14 (50%) in the end-tidal CO2 group and 2 of 14 (14%) in the standard group (p = 0.04). The chest compression rate averaged 143 ± 10/min in the end-tidal CO2 group and 102 ± 2/min in the standard group (p tidal CO2-guided chest compression delivery. The response of the relaxation arterial pressure and cerebral perfusion pressure to the initial epinephrine administration was greater in the end-tidal CO2 group than in the standard group (p = 0.01 and p = 0.03, respectively). The prevalence of resuscitation-related injuries was similar between groups. End-tidal CO2-guided chest compression delivery is an effective resuscitation method that improves early survival after prolonged asphyxial arrest in this neonatal piglet model. Optimizing end-tidal CO2 levels during cardiopulmonary resuscitation required that chest compression delivery rate exceed current guidelines

  4. Ventilatory effects of hypercapnic end-tidal PCO2 clamps during aerobic exercise of varying intensity.

    Science.gov (United States)

    Essfeld, D; Hoffmann, U; Stegemann, J

    1990-01-01

    Nine subjects performed a sequence of sustained and randomised changes between 40 W and 100 W on a cycle ergometer while the end-tidal PO2 was kept close to 17.3 kPa (130 mm Hg) by means of a dynamic forcing technique (reference experiment). In a second series inspiratory CO2 was additionally manipulated so as to hold end-tidal PCO2 (PETCO2) near 6.5 kPa (49 mm Hg; 'CO2-clamp' experiment). By this forcing PETCO2 oscillations were attenuated and more evenly distributed over the frequency range. Ventilation (VT) responded to this manoeuvre with an upward trend that could not be ascribed to a slow CO2-response component, changes in metabolic rate or a dissociation of end-tidal and arterial PCO2. VT differences between reference and CO2-clamp experiments were abolished within a 3-min period following the termination of the external CO2 control. The present results suggest that the CO2-H+ stimulus plays a major role in adjusting ventilation when exercise intensity is decreased. The underlying CO2 effect appears to be neither additive nor bi-directionally symmetrical.

  5. Haemodynamic and end tidal CO2 changes state after inflation and deflation of pneumatic tourniquet on extremities.

    Science.gov (United States)

    Zaman, S M; Islam, M M; Chowdhury, K K; Rickta, D; Ireen, S T; Choudhury, M R; Alam, M

    2010-10-01

    The use of a tourniquet for obtaining a bloodless field is an essential and accepted tool for extremity surgery. A prospective study was done on 30 adult patients undergoing elective limb surgery requiring tourniquet application for haemodynamic and End tidal CO2 (EtCO2) changes. After the induction of general anaesthesia a tourniquet was applied on the limb. There was gradual increase in heart rate & EtCO2 through out the whole period of tourniquet inflation. There was also significant increase of mean arterial pressure during the inflation period. At the end of surgery tourniquet was deflated. Tourniquet time was 76.83+/-16.94 minutes. After deflation of the tourniquet, heart rate & EtCO2 value increased & the values were maximum at 5 minutes. These values came down to the base line at 15 minutes. There was significant decrease of mean arterial pressure (MAP) at 5 minute; it also came to the base at 15 minute. These changes are usually benign but can be significant in patients with co-existing cardiovascular & intracranial diseases. In conclusion, we recommend the haemodynamic and End tidal CO2 monitoring as well as rapid fluid infusion along with hyperventilation for 15-30 minutes after deflation of tourniquet.

  6. [Transbronchoscopic end-tidal carbon dioxide detection for location of the leading bronchus in patients with pneumothorax].

    Science.gov (United States)

    Zeng, Yiming; Lin, Huihuang

    2015-04-01

    To evaluate the effect of end-tidal carbon dioxide (EtCO2) detection for location of the leading bronchus in patients with pneumothorax. Transbronchoscopic EtCO2 detection was performed in 4 patients with intractable pneumothorax in whom transbronchoscopic balloon detection failed to localize the leading bronchus. A specific bronchus was suspected to be the leading bronchus when its EtCO2 value was significantly lower than that of the main bronchus of the affected lung. After the pleural air leakage was successfully sealed by bronchial occlusion of the suspected bronchus, the EtCO2 was confirmed to indicate the leading bronchus. Transbronchoscopic EtCO2 detection successfully located the leading bronchus in all 4 patients. Transbronchoscopic EtCO2 detection is a new method of locating the leading bronchus in patients with intractable pneumothorax.

  7. Metabolic effects of Carbon Dioxide (CO 2 ) insufflation during ...

    African Journals Online (AJOL)

    Metabolic effects of Carbon Dioxide (CO 2 ) insufflation during laparoscopic surgery: changes in pH, arterial partial Pressure of Carbon Dioxide (PaCo 2 ) and End Tidal Carbon Dioxide (EtCO 2 ) ... Respiratory adjustments were done for EtCO2 levels above 60mmHg or SPO2 below 92% or adverse haemodynamic changes.

  8. 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.

  9. Use of 'ideal' alveolar air equations and corrected end-tidal PCO2 to estimate arterial PCO2 and physiological dead space during exercise in patients with heart failure.

    Science.gov (United States)

    Van Iterson, Erik H; Olson, Thomas P

    2018-01-01

    Arterial CO 2 tension (PaCO 2 ) and physiological dead space (V D ) are not routinely measured during clinical cardiopulmonary exercise testing (CPET). Abnormal changes in PaCO 2 accompanied by increased V D directly contribute to impaired exercise ventilatory function in heart failure (HF). Because arterial catheterization is not standard practice during CPET, this study tested the construct validity of PaCO 2 and V D prediction models using 'ideal' alveolar air equations and basic ventilation and gas-exchangegas exchange measurements during CPET in HF. Forty-seven NYHA class II/III HF (LVEF=21±7%; age=55±9years; male=89%; BMI=28±5kg/m 2 ) performed step-wise cycle ergometry CPET to volitional fatigue. Breath-by-breath ventilation and gas exchange were measured continuously. Steady-state PaCO 2 was measured at rest and peak exercise via radial arterial catheterization. Criterion V D was calculated via 'ideal' alveolar equations, whereas PaCO 2 or V D models were based on end-tidal CO 2 tension (P ET CO 2 ), tidal volume (V T ), and/or weight. Criterion measurements of PaCO 2 (38±5 vs. 33±5mmHg, Pgas exchange and ventilatory responses demonstrate acceptable agreement with criterion measurements at peak exercise in HF patients. Routine assessment of PaCO 2 and V D can be used to improve interpretability of exercise ventilatory responses in HF. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  10. End-tidal control vs. manually controlled minimal-flow anesthesia: a prospective comparative trial.

    Science.gov (United States)

    Wetz, A J; Mueller, M M; Walliser, K; Foest, C; Wand, S; Brandes, I F; Waeschle, R M; Bauer, M

    2017-11-01

    To ensure safe general anesthesia, manually controlled anesthesia requires constant monitoring and numerous manual adjustments of the gas dosage, especially for low- and minimal-flow anesthesia. Oxygen flow-rate and administration of volatile anesthetics can also be controlled automatically by anesthesia machines using the end-tidal control technique, which ensures constant end-tidal concentrations of oxygen and anesthetic gas via feedback and continuous adjustment mechanisms. We investigated the hypothesis that end-tidal control is superior to manually controlled minimal-flow anesthesia (0.5 l/min). In this prospective trial, we included 64 patients undergoing elective surgery under general anesthesia. We analyzed the precision of maintenance of the sevoflurane concentration (1.2-1.4%) and expiratory oxygen (35-40%) and the number of necessary adjustments. Target-concentrations of sevoflurane and oxygen were maintained at more stable levels with the use of end-tidal control (during the first 15 min 28% vs. 51% and from 15 to 60 min 1% vs. 19% deviation from sevoflurane target, P tidal oxygen (5, IQR 3-6). The target-concentrations were reached earlier with the use of end-tidal compared with manual controlled minimal-flow anesthesia but required slightly greater use of anesthetic agents (6.9 vs. 6.0 ml/h). End-tidal control is a superior technique for setting and maintaining oxygen and anesthetic gas concentrations in a stable and rapid manner compared with manual control. Consequently, end-tidal control can effectively support the anesthetist. © 2017 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  11. 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 VE (Δ VE 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

  12. Financial and environmental costs of manual versus automated control of end-tidal gas concentrations.

    Science.gov (United States)

    Tay, S; Weinberg, L; Peyton, P; Story, D; Briedis, J

    2013-01-01

    Emerging technologies that reduce the economic and environmental costs of anaesthesia have had limited assessment. We hypothesised that automated control of end-tidal gases, a new feature in anaesthesia machines, will consistently reduce volatile agent consumption cost and greenhouse gas emissions. As part of the planned replacement of anaesthesia machines in a tertiary hospital, we performed a prospective before and after study comparing the cost and greenhouse gas emissions of isoflurane, sevoflurane and desflurane when using manual versus automated control of end-tidal gases. We analysed 3675 general anaesthesia cases with inhalational agents: 1865 using manual control and 1810 using automated control. Volatile agent cost was $18.87/hour using manual control and $13.82/hour using automated control: mean decrease $5.05/hour (95% confidence interval: $0.88-9.22/hour, P=0.0243). The 100-year global warming potential decreased from 23.2 kg/hour of carbon dioxide equivalents to 13.0 kg/hour: mean decrease 10.2 kg/hour (95% confidence interval: 2.7-17.7 kg/hour, P=0.0179). Automated control reduced costs by 27%. Greenhouse gas emissions decreased by 44%, a greater than expected decrease facilitated by a proportional reduction in desflurane use. Automated control of end-tidal gases increases participation in low flow anaesthesia with economic and environmental benefits.

  13. A quantitative comparison of physiologic indicators of cardiopulmonary resuscitation quality: Diastolic blood pressure versus end-tidal carbon dioxide.

    Science.gov (United States)

    Morgan, Ryan W; French, Benjamin; Kilbaugh, Todd J; Naim, Maryam Y; Wolfe, Heather; Bratinov, George; Shoap, Wesley; Hsieh, Ting-Chang; Nadkarni, Vinay M; Berg, Robert A; Sutton, Robert M

    2016-07-01

    The American Heart Association (AHA) recommends monitoring invasive arterial diastolic blood pressure (DBP) and end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR) when available. In intensive care unit patients, both may be available to the rescuer. The objective of this study was to compare DBP vs. ETCO2 during CPR as predictors of cardiac arrest survival. In two models of cardiac arrest (primary ventricular fibrillation [VF] and asphyxia-associated VF), 3-month old swine received either standard AHA guideline-based CPR or patient-centric, BP-guided CPR. Mean values of DBP and ETCO2 in the final 2min before the first defibrillation attempt were compared using receiver operating characteristic curves (area under curve [AUC] analysis). The optimal DBP cut point to predict survival was derived and subsequently validated in two independent, randomly generated cohorts. Of 60 animals, 37 (61.7%) survived to 45min. DBP was higher in survivors than in non-survivors (40.6±1.8mmHg vs. 25.9±2.4mmHg; pAUC analysis, DBP was superior to ETCO2 (0.82 vs. 0.60; p=0.025) in discriminating survivors from non-survivors. The optimal DBP cut point in the derivation cohort was 34.1mmHg. In the validation cohort, this cut point demonstrated a sensitivity of 0.78, specificity of 0.81, positive predictive value of 0.64, and negative predictive value of 0.89 for survival. In both primary and asphyxia-associated VF porcine models of cardiac arrest, DBP discriminates survivors from non-survivors better than ETCO2. Failure to attain a DBP >34mmHg during CPR is highly predictive of non-survival. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Appropriate xenon-inhalation time in xenon-enhanced CT using the end-tidal gas-sampling method

    Energy Technology Data Exchange (ETDEWEB)

    Asada, Hideo; Furuhata, Shigeru; Onozuka, Satoshi; Uchida, Koichi; Fujii, Koji; Suga, Sadao; Kawase, Takeshi; Toya, Shigeo; Shiga, Hayao

    1988-12-01

    For the end-tidal gas-sampling method of xenon-enhanced CT (Xe-CT), the respective functional images of K, lambda, and the regional cerebral blood flow (rCBF) were studied and compared using the data at 7-, 10-, 15- and 25-minute inhalations. The most appropriate inhalation time of xenon gas was evaluated in 14 clinical cases. An end-tidal xenon curve which represents the arterial xenon concentration was monitored with a xenon analyzer; the xenon concentration was gradually increased to a level of 50% by using a xenon inhalator with a closed circuit to prevent the overestimation of the xenon concentration sampled from the mask. Serial CT scans were taken over a period of 25 minutes of inhalation. The functional images of K, lambda, and rCBF were calculated for serial CT scans for 7, 10, 15 and 25 minutes using Fick's equation. Those various images and absolute values were then compared. The rCBF value of a 15-minute inhalation was approximately 15% greater than that of 25 minutes, while the values of K, lambda, rCBF from a 15-minute inhalation were significantly correlated to those from 25 minutes. The regression line made it possible to estimate 25-minute inhalation values from those of 15 minutes. In imaging, the rCBF mapping of the 15-minute inhalation was found to be more reliable than that of 25 minutes. This study suggests that the minimal time of xenon inhalation is 15 minutes for the end-tidal gas-sampling method. A longer inhalation may be necessary for the estimation of rCBF in the low-flow area, such as the white matter or the pathological region.

  15. Measuring End-Tidal Carbon Monoxide of Jaundiced Neonates in the Birth Hospital to Identify Those with Hemolysis.

    Science.gov (United States)

    Christensen, Robert D; Malleske, Daniel T; Lambert, Diane K; Baer, Vickie L; Prchal, Josef T; Denson, Leslie E; Gerday, Erick; Weaver Lewis, Kimberlee A; Shepherd, JuLyn G

    2016-01-01

    End-tidal breath carbon monoxide (ETCOc) levels correlate with catabolism of heme, but until recently, this measurement was not readily available for application to neonatology practice. We performed a prospective, multihospital, test-of-concept study where ETCOc was measured during the birth hospitalization of neonates with a total bilirubin (TB) value >75th percentile on the Bhutani bilirubin nomogram. This was done to test the feasibility and ease of use of this new device. Neonates with an elevated ETCOc (with a >95th percentile reference interval previously established) were labeled as having 'hemolytic jaundice'. We recommended a follow-up TB check jaundice treatment compared with a rate of 2.99 rehospitalizations per 100 control neonates who had a TB value >75th percentile (p = 0.079). ETCOc measurement is a feasible means of assessing hemolysis in jaundiced neonates during the birth hospitalization. When hemolysis is identified, parents are likely to comply with instructions to bring the infant for a TB checkup <24 h after discharge home. © 2015 S. Karger AG, Basel.

  16. Monitoring carbon dioxide in mechanically ventilated patients during hyperbaric treatment

    DEFF Research Database (Denmark)

    Bjerregård, Asger; Jansen, Erik

    2012-01-01

    Measurement of the arterial carbon dioxide (P(a)CO(2)) is an established part of the monitoring of mechanically ventilated patients. Other ways to get information about carbon dioxide in the patient are measurement of end-tidal carbon dioxide (P(ET)CO(2)) and transcutaneous carbon dioxide (PTCCO2......). Carbon dioxide in the blood and cerebral tissue has great influence on vasoactivity and thereby blood volume of the brain. We have found no studies on the correlation between P(ET)CO(2) or P(TC)CO(2), and P(a)CO(2) during hyperbaric oxygen therapy (HBOT)....

  17. Hydrologically mediated iron reduction/oxidation fluctuations and dissolved organic carbon exports in tidal wetlands

    Science.gov (United States)

    Guimond, J. A.; Seyfferth, A.; Michael, H. A.

    2017-12-01

    Salt marshes are biogeochemical hotspots where large quantities of carbon are processed and stored. High primary productivity and deposition of carbon-laden sediment enable salt marsh soils to accumulate and store organic carbon. Conversely, salt marshes can laterally export carbon from the marsh platform to the tidal channel and eventually the ocean via tidal pumping. However, carbon export studies largely focus on tidal channels, missing key physical and biogeochemical mechanisms driving the mobilization of dissolved organic carbon (DOC) within the marsh platform and limiting our understanding of and ability to predict coastal carbon dynamics. We hypothesize that iron redox dynamics mediate the mobilization/immobilization of DOC in the top 30 cm of salt marsh sediment near tidal channels. The mobilized DOC can then diffuse into the flooded surface water or be advected to tidal channels. To elucidate DOC dynamics driven by iron redox cycles, we measured porewater DOC, Fe(II), total iron, total sulfate, pH, redox potential, and electrical conductivity (EC) beside the creek, at the marsh levee, and in the marsh interior in a mid-latitude tidal salt marsh in Dover, Delaware. Samples were collected at multiple tide stages during a spring and neap tide at depths of 5-75cm. Samples were also collected from the tidal channel. Continuous Eh measurements were made using in-situ electrodes. A prior study shows that DOC and Fe(II) concentrations vary spatially across the marsh. Redox conditions near the creek are affected by tidal oscillations. High tides saturate the soil and decrease redox potential, whereas at low tide, oxygen enters the sediment and increases the Eh. This pattern is always seen in the top 7-10cm of sediment, with more constant low Eh at depth. However, during neap tides, this signal penetrates deeper. Thus, between the creek and marsh levee, hydrology mediates redox conditions. Based on porewater chemistry, if DOC mobilization can be linked to redox

  18. 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

  19. End-tidal carbon dioxide monitoring during flexible fiberoptic ...

    African Journals Online (AJOL)

    In recent years, flexible fiberoptic bronchoscopy (FFB) has been applied for diagnostic and some therapeutic purposes. During FFB and even in the presence of supplemental oxygen, hypoventilation leading to hypoxia and desaturation may occur; this is aggravated by the use of suction. Arterial oxygen saturation is usually ...

  20. The effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.

    Science.gov (United States)

    Klein, Klaus Ulrich; Glaser, Martin; Reisch, Robert; Tresch, Achim; Werner, Christian; Engelhard, Kristin

    2009-07-01

    Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. Twenty-six neurosurgical patients were randomly assigned to anesthesia with 1.4% or 2.0% sevoflurane end-tidal concentration. After craniotomy, a fiberoptic probe was applied on a macroscopically healthy surface of cerebral tissue next to the site of surgery. Simultaneous measurements in 2 and 8 mm cerebral depth were performed in each patient during lower (35 mm Hg) and higher (45 mm Hg) levels (random order) of arterial carbon dioxide partial pressure (PaCO2). The principle of these measurements relies on the combination of laser-Doppler flowmetry (rvCBF, rvVelo) and photo-spectrometry (srvO2, rvHb). Linear models were fitted to test changes of end points (rvCBF, rvVelo, srvO2, rvHb) in response to lower and higher levels of PaCO2, 1.4% and 2.0% sevoflurane end-tidal concentration, and 2 and 8 mm cerebral depth. RvCBF and rvVelo were elevated by PaCO2 independent of sevoflurane concentration in 2 and 8 mm depth of cerebral tissue (P oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.

  1. Anesthetic Overdose Leading to Cardiac Arrest Diagnosed by End-Tidal Inhalant Concentration Analysis in a Dog

    Directory of Open Access Journals (Sweden)

    Erik Hofmeister

    2013-01-01

    Full Text Available A 5-year-old male-castrated Cocker Spaniel presented to the Veterinary Teaching Hospital of the University of Georgia for a total ear canal ablation. Premedication was with carprofen 2.2 mg/kg SQ, hydromorphone 0.1 mg/kg IM, diazepam 0.2 mg/kg IM, and glycopyrrolate 0.01 mg/kg IM. The patient was induced with lidocaine 2 mg/kg IV and etomidate 1 mg/kg IV and maintained with sevoflurane and a constant rate infusion consisting of lidocaine 0.05 mg/kg/min. Before surgery start, the patient’s systolic arterial blood pressure was 110 mmHg, heart rate (HR was 85 beats/min, respiratory rate was 8 breaths/min, end-tidal sevoflurane concentration was 3.2%, and end-tidal CO2 (ETCO2 was 23 mmHg. As a scrub was being performed, the patient’s HR abruptly dropped to 20 beats/min over the course of 2 minutes. His ETCO2 simultaneously decreased to 16 mmHg. At this time, cardiopulmonary arrest was diagnosed. After two minutes of resuscitation, a spontaneous heart beat was obtained and the patient was successfully recovered and discharged without further incident. The cardiac arrest in this case is most likely attributable to an overdose of inhalant anesthesia, which was diagnosed by an anesthetic inhalant concentration monitor. A gas analyzer may be a helpful contribution to the small animal practitioner, particularly those performing more lengthy or complex procedures.

  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. Mechanics of spatulated end-to-end artery-to-vein anastomoses.

    Science.gov (United States)

    Morasch, M D; Dobrin, P B; Dong, Q S; Mrkvicka, R

    1998-01-01

    It previously has been shown that in straight end-to-end artery-to-vein anastomoses, maximum dimensions are obtained with an interrupted suture line. Nearly equivalent dimensions are obtained with a continuous compliant polybutester suture (Novafil), and the smallest dimensions are obtained with a continuous noncompliant polypropylene suture (Surgilene). The present study was undertaken to examine these suture techniques in a spatulated or beveled anastomosis in living dogs. Anastomoses were constructed using continuous 6-0 polypropylene (Surgilene), continuous 6-0 polybutester (Novafil), or interrupted 6-0 polypropylene or polybutester. Thirty minutes after construction, the artery, vein, and beveled anastomoses were excised, restored to in situ length and pressurized with the lumen filled with a dilute suspension of barium sulfate. High resolution radiographs were obtained at 25 mmHg pressure increments up to 200 mmHg. Dimensions and compliance were determined from the radiographic images. Results showed that, unlike straight artery-to-vein anastomoses, there were no differences in the dimensions or compliance of spatulated anastomoses with continuous Surgilene, continuous Novafil, or interrupted suture techniques. Therefore a continuous suture technique is acceptable when constructing spatulated artery-to-vein anastomoses in patients.

  4. Effect of breathing fluctuations on cerebral blood flow in demented patients and its correction method using end-tidal CO/sub 2/ concentration

    Energy Technology Data Exchange (ETDEWEB)

    Komatani, Akio; Yamaguchi, Koichi; Kera, Masahiro; Takanashi, Toshiyasu; Shinohara, Masao; Kawakatsu, Shinobu; Yazaki, Mitsuyasu

    1989-02-01

    During mouthpiece respiration of Xe-133 for a measurement of regional cerebral blood flow (rCBF), the breathing pattern of patients fluctuated and it caused a change of end-tidal CO/sub 2/ concentration that had an excellent correlation with PaCO/sub 2/ in patients without respiratory disease. The end-tidal CO/sub 2/ concentration of demented patients varied within lower ranges than senile control group. The range of fluctuation on the end-tidal CO/sub 2/ concentration was dependent on the type and the degree of dementia, and it fluctuated most widely at the middle stage of Alzheimer disease. Mean cerebral blood flow increased by 13.9% for each l% increase in end-tidal CO/sub 2/ concentration (3.6%/mmHg PaCO/sub 2/) in the case of demented patients without cerebrovascular disease. To improve the reliability of rCBF in demented patients, especially in Alzheimer disease, the correction of rCBF data for end-tidal CO/sub 2/ concentration should be performed.

  5. ROBUST CONTROL OF END-TIDAL CO2 USING THE H∞ LOOP-SHAPING APPROACH

    Directory of Open Access Journals (Sweden)

    Anake Pomprapa

    2013-12-01

    Full Text Available Mechanically ventilated patients require appropriate settings of respiratory control variables to maintain acceptable gas exchange. To control the carbon dioxide (CO2 level effectively and automatically, system identification based on a human subject was performed using a linear affine model and a nonlinear Hammerstein structure. Subsequently, a robust controller was designed using the H∞ loop-shaping approach, which synthesizes the optimal controller based on a specific objective by achieving stability with guaranteed performance. For demonstration purposes, the closed-loop control ventilation system was successfully tested in a human volunteer. The experimental results indicate that the blood CO2 level may indeed be controlled noninvasively by measuring end-tidal CO2 from expired air. Keeping the limited amount of experimental data in mind, we conclude that H∞ loop-shaping may be a promising technique for control of mechanical ventilation in patients with respiratory insufficiency.

  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. Randomized trial of low versus high carbon dioxide insufflation pressures in posterior retroperitoneoscopic adrenalectomy.

    Science.gov (United States)

    Fraser, Sheila; Norlén, Olov; Bender, Kyle; Davidson, Joanne; Bajenov, Sonya; Fahey, David; Li, Shawn; Sidhu, Stan; Sywak, Mark

    2018-05-01

    Posterior retroperitoneoscopic adrenalectomy has gained widespread acceptance for the removal of benign adrenal tumors. Higher insufflation pressures using carbon dioxide (CO 2 ) are required, although the ideal starting pressure is unclear. This prospective, randomized, single-blinded, study aims to compare physiologic differences with 2 different CO 2 insufflation pressures during posterior retroperitoneoscopic adrenalectomy. Participants were randomly assigned to a starting insufflation pressure of 20 mm Hg (low pressure) or 25 mm Hg (high pressure). The primary outcome measure was partial pressure of arterial CO 2 at 60 minutes. Secondary outcomes included end-tidal CO 2 , arterial pH, blood pressure, and peak airway pressure. Breaches of protocol to change insufflation pressure were permitted if required and were recorded. A prospective randomized trial including 31 patients (low pressure: n = 16; high pressure: n = 15) was undertaken. At 60 minutes, the high pressure group had greater mean partial pressure of arterial CO 2 (64 vs 50 mm Hg, P = .003) and end-tidal CO 2 (54 vs 45 mm Hg, P = .008) and a lesser pH (7.21 vs 7.29, P = .0005). There were no significant differences in base excess, peak airway pressure, operative time, or duration of hospital stay. Clinically indicated protocol breaches were more common in the low pressure than the high pressure group (8 vs 3, P = .03). In posterior retroperitoneoscopic adrenalectomy, greater insufflation pressures are associated with greater partial pressure of arterial CO 2 and end-tidal CO 2 and lesser pH at 60 minutes, be significant. Commencing with lesser CO 2 insufflation pressures decreases intraoperative acidosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Tracing organic matter sources of estuarine tidal flat nematodes with stable carbon isotopes

    NARCIS (Netherlands)

    Moens, T.; Luyten, C.; Middelburg, J.J.; Herman, P.M.J.; Vincx, M.

    2002-01-01

    The present study explores the use of stable carbon isotopes to trace organic matter sources of intertidal nematodes in the Schelde estuary (SW Netherlands). Stable carbon isotope signatures of nematodes from a saltmarsh and 4 tidal flat stations were determined in spring and winter situations, and

  9. A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

    Science.gov (United States)

    Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

    2018-05-01

    Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%-44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all

  10. A forward-looking, national-scale remote sensing-based model of tidal marsh aboveground carbon stocks

    Science.gov (United States)

    Holmquist, J. R.; Byrd, K. B.; Ballanti, L.; Nguyen, D.; Simard, M.; Windham-Myers, L.; Thomas, N.

    2017-12-01

    Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our goal was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). To meet this objective we developed the first national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest algorithm we tested Sentinel-1 radar backscatter metrics and Landsat vegetation indices as predictors of biomass. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n=409, RMSE=310 g/m2, 10.3% normalized RMSE), successfully predicted biomass and carbon for a range of marsh plant functional types defined by height, leaf angle and growth form. Model error was reduced by scaling field measured biomass by Landsat fraction green vegetation derived from object-based classification of National Agriculture Imagery Program imagery. We generated 30m resolution biomass maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map for each region. With a mean plant %C of 44.1% (n=1384, 95% C.I.=43.99% - 44.37%) we estimated mean aboveground carbon densities (Mg/ha) and total carbon stocks for each wetland type for each region. Louisiana palustrine emergent marshes had the highest C density (2.67 ±0.08 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ±0.06 Mg/ha). This modeling and data synthesis effort will allow for aboveground

  11. Treatment of a partially thrombosed giant aneurysm of the vertebral artery by aneurysm trapping and direct vertebral artery-posterior inferior cerebellar artery end-to-end anastomosis: technical case report.

    Science.gov (United States)

    Benes, Ludwig; Kappus, Christoph; Sure, Ulrich; Bertalanffy, Helmut

    2006-07-01

    The purpose of this article is to focus for the first time on the operative management of a direct vertebral artery (VA)-posterior inferior cerebellar artery (PICA) end-to-end anastomosis in a partially thrombosed giant VA-PICA-complex aneurysm and to underline its usefulness as an additional treatment option. The operative technique of a direct VA-PICA end-to-end anatomosis is described in detail. The VA was entering the large aneurysm sack. Distally, the PICA originated from the aneurysm sack-VA-complex. The donor and recipient vessel were cut close to the aneurysm. Whereas the VA was cut in a straight manner, the PICA was cut at an oblique 45-degree angle to enlarge the vascular end diameter. Vessel ends were flushed with heparinized saline and sutured. The thrombotic material inside the aneurysm sack was removed and the distal VA clipped, leaving the anterior spinal artery and brainstem perforators free. The patient regained consciousness without additional morbidity. Magnetic resonance imaging scans revealed a completely decompressed brainstem without infarction. The postoperative angiograms demonstrated a good filling of the anastomosed PICA. Despite the caliber mistmatch of these two vessels the direct VA-PICA end-to-end anastomosis provides an accurate alternative in addition to other anastomoses and bypass techniques, when donor and recipient vessels are suitable and medullary perforators do not have to be disrupted.

  12. Tidal wetland fluxes of dissolved organic carbon and sediment at Browns Island, California: initial evaluation

    Science.gov (United States)

    Ganju, N.K.; Bergamaschi, B.; Schoellhamer, D.H.

    2003-01-01

    Carbon and sediment fluxes from tidal wetlands are of increasing concern in the Sacramento-San Joaquin River Delta (Delta), because of drinking water issues and habitat restoration efforts. Certain forms of dissolved organic carbon (DOC) react with disinfecting chemicals used to treat drinking water, to form disinfection byproducts (DBPs), some of which are potential carcinogens. The contribution of DBP precursors by tidal wetlands is unknown. Sediment transport to and from tidal wetlands determines the potential for marsh accretion, thereby affecting habitat formation.Water, carbon, and sediment flux were measured in the main channel of Browns Island, a tidal wetland located at the confluence of Suisun Bay and the Delta. In-situ instrumentation were deployed between May 3 and May 21, 2002. Water flux was measured using acoustic Doppler current profilers and the index-velocity method. DOC concentrations were measured using calibrated ultraviolet absorbance and fluorescence instruments. Suspended-sediment concentrations were measured using a calibrated nephelometric turbidity sensor. Tidally averaged water flux through the channel was dependent on water surface elevations in Suisun Bay. Strong westerly winds resulted in higher water surface elevations in the area east of Browns Island, causing seaward flow, while subsiding winds reversed this effect. Peak ebb flow transported 36% more water than peak flood flow, indicating an ebb-dominant system. DOC concentrations were affected strongly by porewater drainage from the banks of the channel. Peak DOC concentrations were observed during slack after ebb, when the most porewater drained into the channel. Suspended-sediment concentrations were controlled by tidal currents that mobilized sediment from the channel bed, and stronger tides mobilized more sediment than the weaker tides. Sediment was transported mainly to the island during the 2-week monitoring period, though short periods of export occurred during the spring

  13. Sediment Accretion, Carbon Sequestration, and Resilience to Sea Level Rise in Natural and Recently Restored Tidal Marshes

    Science.gov (United States)

    Poppe, K.; Rybczyk, J.; Parr, L.; Merrill, A.

    2017-12-01

    Tidal marshes are typically productive and depositional environments potentially conducive to high rates of carbon sequestration. Though they have been recognized globally for their ability to store "blue carbon", there is a paucity of comprehensive site-scale data from the Pacific Northwest U.S. Here we report carbon stocks and sequestration rates for an existing and a recently restored brackish marsh in the Stillaguamish River Estuary, in Puget Sound, Washington. The Stillaguamish River discharges into the Port Susan Bay Preserve which contains a 150-acre tidal marsh restoration site that was reintroduced to the tidal regime in 2012 from its previous use as diked and drained farmland. We hypothesized that the restoration would not only maximize carbon storage in former tidal wetlands but also, through the accumulation of organic and mineral matter, enhance these systems' resilience to rising sea levels. We collected sediment cores from 13 sites across the estuary, within and outside of the restoration area, to determine bulk density, organic and carbon content with depth, long-term accretion rates, and belowground biomass. We also measured aboveground net primary productivity. Carbon stocks at each site were partitioned into three components as recommended by the IPCC: aboveground biomass, belowground biomass, and sediment carbon. We additionally measured elevation change with surface elevation tables (SETs). Mean sediment carbon stocks in the upper 30 cm of sediment within the restoration area (6.45 kg C/m2) were similar to those measured in the adjacent natural marsh (6.82 kg C/m2). However, mean elevation change, as measured by SETs, were substantially higher in the restoration area (3.10 cm/yr) than in the natural marsh sites (0.79 cm/yr). As a result, carbon accumulation rates were also higher in the restoration area (821 g C/m2/yr) compared to the natural marsh sites (195 g C/m2/yr).

  14. Coastal Carbon Dynamics as a New Chapter in SOCCR2: Tidal Wetlands and Estuaries

    Science.gov (United States)

    Windham-Myers, L.; Megonigal, P.; Cai, W. J.; Hopkinson, C.; Wang, A. Z.; Andersson, A. J.; Hinson, A.; Lagomasino, D.; Peteet, D. M.; Giri, C. P.; Howard, J.; Tang, J.; Crosswell, J.; Martin Hernandez-Ayon, J. M.; Dunton, K. H.; Kroeger, K. D.; Paulsen, M. L.; Allison, M. A.; Siedlecki, S. A.; Alin, S. R.; Hu, X.; Tzortziou, M.; Najjar, R.; Schafer, K. V.; Watson, E.; Pidgeon, E.

    2016-12-01

    Estuaries and tidal wetlands have been identified as distinct landscape elements for carbon cycling, worthy of a chapter in the pending State of the Carbon Cycle Report - version 2. Despite relatively small aerial coverage compared to other subsystems, tidal wetlands and estuaries have the greatest influence on carbon dynamics of any coastal ocean subsystem. As conduits that filter all material passing between land and the sea, they also exhibit the highest transfer rates of CO2 with the atmosphere of any of the coastal ocean subsystems. Carbon dynamics in estuaries and wetlands are constantly changing, reflecting geomorphic and ecological responses to long and short-term perturbations in external drivers such as sea-level rise, climate change, nutrient loading and land-use change. The influence of these drivers are profound in coastal systems, often more so than in inland wetlands or open ocean environments, and thus require distinct attention to patterns and processes associated with coastal ecosystem functioning, including carbon sequestration services in tidal wetland soils. This new chapter focusses on data sources available in North America to: (1) assess the current state of carbon stocks and fluxes in coastal settings, (2) document understanding of drivers associated with significant fluxes and stocks, and (3) synthesize carbon dynamics from a global context to regional perspectives (East, West, Gulf and high-latitude coastlines). Insights from remote sensing, in situ field data, and numerical models have advanced our ability to monitor and project carbon cycling in this dynamic and narrow fringe at the land-ocean interface. This synthetic chapter will address how these advances can help in decision making, as well as address remaining gaps in our knowledge and monitoring capabilities for these diverse and productive habitats.

  15. 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

  16. 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.

  17. A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

    Science.gov (United States)

    Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

    2018-01-01

    Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%–44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had

  18. A long-term comparison of carbon sequestration rates in impounded and naturally tidal freshwater marshes along the lower Waccamaw River, South Carolina

    Science.gov (United States)

    Drexler, Judith Z.; Krauss, Ken W.; Sasser, M. Craig; Fuller, Christopher C.; Swarzenski, Christopher M.; Powell, Amber; Swanson, Kathleen M.; Orlando, James L.

    2013-01-01

    Carbon storage was compared between impounded and naturally tidal freshwater marshes along the Lower Waccamaw River in South Carolina, USA. Soil cores were collected in (1) naturally tidal, (2) moist soil (impounded, seasonally drained since ~1970), and (3) deeply flooded “treatments” (impounded, flooded to ~90 cm since ~2002). Cores were analyzed for % organic carbon, % total carbon, bulk density, and 210Pb and 137Cs for dating purposes. Carbon sequestration rates ranged from 25 to 200 g C m−2 yr−1 (moist soil), 80–435 g C m−2 yr−1 (naturally tidal), and 100–250 g C m−2 yr−1 (deeply flooded). The moist soil and naturally tidal treatments were compared over a period of 40 years. The naturally tidal treatment had significantly higher carbon storage (mean = 219 g C m−2 yr−1 vs. mean = 91 g C m−2 yr−1) and four times the vertical accretion rate (mean = 0.84 cm yr−1 vs. mean = 0.21 cm yr−1) of the moist soil treatment. The results strongly suggest that the long drainage period in moist soil management limits carbon storage over time. Managers across the National Wildlife Refuge system have an opportunity to increase carbon storage by minimizing drainage in impoundments as much as practicable.

  19. The spatial distribution of soil organic carbon in tidal wetland soils of the continental United States.

    Science.gov (United States)

    Hinson, Audra L; Feagin, Rusty A; Eriksson, Marian; Najjar, Raymond G; Herrmann, Maria; Bianchi, Thomas S; Kemp, Michael; Hutchings, Jack A; Crooks, Steve; Boutton, Thomas

    2017-12-01

    Tidal wetlands contain large reservoirs of carbon in their soils and can sequester carbon dioxide (CO 2 ) at a greater rate per unit area than nearly any other ecosystem. The spatial distribution of this carbon influences climate and wetland policy. To assist with international accords such as the Paris Climate Agreement, national-level assessments such as the United States (U.S.) National Greenhouse Gas Inventory, and regional, state, local, and project-level evaluation of CO 2 sequestration credits, we developed a geodatabase (CoBluCarb) and high-resolution maps of soil organic carbon (SOC) distribution by linking National Wetlands Inventory data with the U.S. Soil Survey Geographic Database. For over 600,000 wetlands, the total carbon stock and organic carbon density was calculated at 5-cm vertical resolution from 0 to 300 cm of depth. Across the continental United States, there are 1,153-1,359 Tg of SOC in the upper 0-100 cm of soils across a total of 24 945.9 km 2 of tidal wetland area, twice as much carbon as the most recent national estimate. Approximately 75% of this carbon was found in estuarine emergent wetlands with freshwater tidal wetlands holding about 19%. The greatest pool of SOC was found within the Atchafalaya/Vermilion Bay complex in Louisiana, containing about 10% of the U.S. total. The average density across all tidal wetlands was 0.071 g cm -3 across 0-15 cm, 0.055 g cm -3 across 0-100 cm, and 0.040 g cm -3 at the 100 cm depth. There is inherent variability between and within individual wetlands; however, we conclude that it is possible to use standardized values at a range of 0-100 cm of the soil profile, to provide first-order quantification and to evaluate future changes in carbon stocks in response to environmental perturbations. This Tier 2-oriented carbon stock assessment provides a scientific method that can be copied by other nations in support of international requirements. © 2017 John Wiley & Sons Ltd.

  20. Tidal effects on net ecosystem exchange of carbon in an estuarine wetland

    Science.gov (United States)

    H. Guo; A. Noormets; B. Zhao; J. Chen; G. Sun; Y. Gu; B. Li; J. Chen

    2009-01-01

    One year of continuous data from two eddy-flux towers established along an elevation gradient incoastal Shanghai was analyzed to evaluate the tidal effect on carbon flux (Fc) over an estuarine wetland.The measured wavelet spectra and cospectra of Fc and other environmental factors demonstrated thatthe...

  1. Physical and Biological Regulation of Carbon Sequestration in Tidal Marshes

    Science.gov (United States)

    Morris, J. T.; Callaway, J.

    2017-12-01

    The rate of carbon sequestration in tidal marshes is regulated by complex feedbacks among biological and physical factors including the rate of sea-level rise (SLR), biomass production, tidal amplitude, and the concentration of suspended sediment. We used the Marsh Equilibrium Model (MEM) to explore the effects on C-sequestration across a wide range of permutations of these variables. C-sequestration increased with the rate of SLR to a maximum, then down to a vanishing point at higher SLR when marshes convert to mudflats. An acceleration in SLR will increase C-sequestration in marshes that can keep pace, but at high rates of SLR this is only possible with high biomass and suspended sediment concentrations. We found that there were no feasible solutions at SLR >13 mm/yr for permutations of variables that characterize the great majority of tidal marshes, i.e., the equilibrium elevation exists below the lower vertical limit for survival of marsh vegetation. The rate of SLR resulting in maximum C-sequestration varies with biomass production. C-sequestration rates at SLR=1 mm/yr averaged only 36 g C m-2 yr-1, but at the highest maximum biomass tested (5000 g/m2) the mean C-sequestration reached 399 g C m-2 yr-1 at SLR = 14 mm/yr. The empirical estimate of C-sequestration in a core dated 50-years overestimates the theoretical long-term rate by 34% for realistic values of decomposition rate and belowground production. The overestimate of the empirical method arises from the live and decaying biomass contained within the carbon inventory above the marker horizon, and overestimates were even greater for shorter surface cores.

  2. User-Friendly Predictive Modeling of Greenhouse Gas (GHG) Fluxes and Carbon Storage in Tidal Wetlands

    Science.gov (United States)

    Ishtiaq, K. S.; Abdul-Aziz, O. I.

    2015-12-01

    We developed user-friendly empirical models to predict instantaneous fluxes of CO2 and CH4 from coastal wetlands based on a small set of dominant hydro-climatic and environmental drivers (e.g., photosynthetically active radiation, soil temperature, water depth, and soil salinity). The dominant predictor variables were systematically identified by applying a robust data-analytics framework on a wide range of possible environmental variables driving wetland greenhouse gas (GHG) fluxes. The method comprised of a multi-layered data-analytics framework, including Pearson correlation analysis, explanatory principal component and factor analyses, and partial least squares regression modeling. The identified dominant predictors were finally utilized to develop power-law based non-linear regression models to predict CO2 and CH4 fluxes under different climatic, land use (nitrogen gradient), tidal hydrology and salinity conditions. Four different tidal wetlands of Waquoit Bay, MA were considered as the case study sites to identify the dominant drivers and evaluate model performance. The study sites were dominated by native Spartina Alterniflora and characterized by frequent flooding and high saline conditions. The model estimated the potential net ecosystem carbon balance (NECB) both in gC/m2 and metric tonC/hectare by up-scaling the instantaneous predicted fluxes to the growing season and accounting for the lateral C flux exchanges between the wetlands and estuary. The entire model was presented in a single Excel spreadsheet as a user-friendly ecological engineering tool. The model can aid the development of appropriate GHG offset protocols for setting monitoring plans for tidal wetland restoration and maintenance projects. The model can also be used to estimate wetland GHG fluxes and potential carbon storage under various IPCC climate change and sea level rise scenarios; facilitating an appropriate management of carbon stocks in tidal wetlands and their incorporation into a

  3. Implementation of a novel postoperative monitoring system using automated Modified Early Warning Scores (MEWS) incorporating end-tidal capnography.

    Science.gov (United States)

    Blankush, Joseph M; Freeman, Robbie; McIlvaine, Joy; Tran, Trung; Nassani, Stephen; Leitman, I Michael

    2017-10-01

    a MEWS warranting a page (rise in MEWS by 2 or 5 or greater)-62 % were false scores inclusive of falsely recorded VS. An abnormal EtCO 2 value resulted in or added to an elevated MEWS score in 29 % of notifications, but 50 % of these included a falsely abnormal EtCO 2 value. To date, no adverse events have occurred. There were no statistically significant demographic, post-operative condition, or pre-existing comorbidity differences between patients who had a majority of true alarms from those who had mostly false-positive alarms. Although not statistically significant, the group of patients in whom automated MEWS suggested greater utility included those with a history of hypertension (p = 0.072) and renal disease (p = 0.084). EtCO 2 monitoring was more likely to be useful in patients with a history of type 2 diabetes, coronary artery disease, and obstructive sleep apnea (p automated MEWS system, modified to include end-tidal CO2 can be feasibly implemented in a hospital ward. Further study is needed to evaluate its clinical utility, including an end-tidal CO 2 score, is feasibly implemented and can be useful in monitoring select post-operative patients for derangements in physiologic metrics. Like any other monitoring system, false alarms may occur at high rates. While further study is needed to determine the additive utility of EtCO 2 in MEWS calculations, this study suggests utility of EtCO 2 in select post-operative patients.

  4. Global carbon sequestration in tidal, saline wetland soils

    Science.gov (United States)

    Chmura, G.L.; Anisfeld, S.C.; Cahoon, D.R.; Lynch, J.C.

    2003-01-01

    Wetlands represent the largest component of the terrestrial biological carbon pool and thus play an important role in global carbon cycles. Most global carbon budgets, however, have focused on dry land ecosystems that extend over large areas and have not accounted for the many small, scattered carbon-storing ecosystems such as tidal saline wetlands. We compiled data for 154 sites in mangroves and salt marshes from the western and eastern Atlantic and Pacific coasts, as well as the Indian Ocean, Mediterranean Ocean, and Gulf of Mexico. The set of sites spans a latitudinal range from 22.4??S in the Indian Ocean to 55.5??N in the northeastern Atlantic. The average soil carbon density of mangrove swamps (0.055 ?? 0.004 g cm-3) is significantly higher than the salt marsh average (0.039 ?? 0.003 g cm-3). Soil carbon density in mangrove swamps and Spartina patens marshes declines with increasing average annual temperature, probably due to increased decay rates at higher temperatures. In contrast, carbon sequestration rates were not significantly different between mangrove swamps and salt marshes. Variability in sediment accumulation rates within marshes is a major control of carbon sequestration rates masking any relationship with climatic parameters. Globally, these combined wetlands store at least 44.6 Tg C yr-1 and probably more, as detailed areal inventories are not available for salt marshes in China and South America. Much attention has been given to the role of freshwater wetlands, particularly northern peatlands, as carbon sinks. In contrast to peatlands, salt marshes and mangroves release negligible amounts of greenhouse gases and store more carbon per unit area. Copyright 2003 by the American Geophysical Union.

  5. Pilot study assessment of dynamic vascular changes in breast cancer with near-infrared tomography from prospectively targeted manipulations of inspired end-tidal partial pressure of oxygen and carbon dioxide.

    Science.gov (United States)

    Jiang, Shudong; Pogue, Brian W; Michaelsen, Kelly E; Jermyn, Michael; Mastanduno, Michael A; Frazee, Tracy E; Kaufman, Peter A; Paulsen, Keith D

    2013-07-01

    The dynamic vascular changes in the breast resulting from manipulation of both inspired end-tidal partial pressure of oxygen and carbon dioxide were imaged using a 30 s per frame frequency-domain near-infrared spectral (NIRS) tomography system. By analyzing the images from five subjects with asymptomatic mammography under different inspired gas stimulation sequences, the mixture that maximized tissue vascular and oxygenation changes was established. These results indicate maximum changes in deoxy-hemoglobin, oxygen saturation, and total hemoglobin of 21, 9, and 3%, respectively. Using this inspired gas manipulation sequence, an individual case study of a subject with locally advanced breast cancer undergoing neoadjuvant chemotherapy (NAC) was analyzed. Dynamic NIRS imaging was performed at different time points during treatment. The maximum tumor dynamic changes in deoxy-hemoglobin increased from less than 7% at cycle 1, day 5 (C1, D5) to 17% at (C1, D28), which indicated a complete response to NAC early during treatment and was subsequently confirmed pathologically at the time of surgery.

  6. Nitrogen and organic carbon cycling processes in tidal marshes and shallow estuarine habitats

    Science.gov (United States)

    Bergamaschi, B. A.; Downing, B. D.; Pellerin, B. A.; Kraus, T. E. C.; Fleck, J.; Fujii, R.

    2016-02-01

    Tidal wetlands and shallow water habitats can be sites of high aquatic productivity, and they have the potential of exchanging this newly produced organic carbon with adjacent deeper habitats. Indeed, export of organic carbon from wetlands and shallow water habitats to pelagic food webs is one of the primary ecosystem functions targeted in tidal wetland restorations. Alternatively, wetlands and shallow water habitats can function as retention areas for nutrients due to the nutrient demand of emergent macrophytes and denitrification in anoxic zones. They can also remove phytoplankton and non-algal particles from the aquatic food webs because the shallower waters can result in higher rates of benthic grazing and higher settling due to lower water velocities. We conducted studies in wetland and channel sites in the San Francisco estuary (USA) to investigate the dynamics of nutrients and carbon production at a variety of temporal scales. We collected continuous time series of nutrients, oxygen, chlorophyll and pH in conjunction with continuous acoustic measurement of water velocity and discharge to provide mass controls and used simple biogeochemical models to assess rates. We found a high degree of temporal variability in individual systems, corresponding to, for example, changes in nutrient supply, water level, light level, wind, wind direction, and other physical factors. There was also large variability among the different systems, probably due to differences in flows and geomorphic features. We compare the aquatic productivity of theses environments and speculate as to the formative elements of each. Our findings demonstrate the complex interaction between physical, chemical, and biological factors that determine the type of production and degree of export from tidal wetlands and shallow water habitats, suggesting that a clearer picture of these processes is important for guiding future large scale restoration efforts.

  7. Monitoring gaseous exchange: implications for nursing care.

    Science.gov (United States)

    Martin, Susan; Wilson, Michael

    2002-02-01

    The purpose of this study is to examine whether a relationship exists between arterial and end-tidal carbon dioxide tension (PaCO2 and PETCO2 respectively) in patients admitted to intensive care units (ICUs), and what the implications it has for nursing care. PaCO2 and PETCO2 are indicators of ventilatory adequacy which is an important aspect of respiratory function. These measures of carbon dioxide tension are obtained via invasive and non-invasive monitoring tools. Measurement of PETCO2 has only recently been introduced into ICUs and its usefulness in these environments is open to debate. A population of 30 intubated patients had 214 simultaneous measurements of PaCO2 and PETCO2 taken over a period of 10 months. The findings indicate that, despite strong significant correlations, PETCO2 cannot be used safely as a substitute for PaCO2 as the arterial/end-tidal carbon dioxide gradient is not constant, nor does capnography provide a consistently reliable indicator of PaCO2.

  8. Efficacy of chest compressions directed by end-tidal CO2 feedback in a pediatric resuscitation model of basic life support.

    Science.gov (United States)

    Hamrick, Jennifer L; Hamrick, Justin T; Lee, Jennifer K; Lee, Benjamin H; Koehler, Raymond C; Shaffner, Donald H

    2014-04-14

    End-tidal carbon dioxide (ETCO2) correlates with systemic blood flow and resuscitation rate during cardiopulmonary resuscitation (CPR) and may potentially direct chest compression performance. We compared ETCO2-directed chest compressions with chest compressions optimized to pediatric basic life support guidelines in an infant swine model to determine the effect on rate of return of spontaneous circulation (ROSC). Forty 2-kg piglets underwent general anesthesia, tracheostomy, placement of vascular catheters, ventricular fibrillation, and 90 seconds of no-flow before receiving 10 or 12 minutes of pediatric basic life support. In the optimized group, chest compressions were optimized by marker, video, and verbal feedback to obtain American Heart Association-recommended depth and rate. In the ETCO2-directed group, compression depth, rate, and hand position were modified to obtain a maximal ETCO2 without video or verbal feedback. After the interval of pediatric basic life support, external defibrillation and intravenous epinephrine were administered for another 10 minutes of CPR or until ROSC. Mean ETCO2 at 10 minutes of CPR was 22.7±7.8 mm Hg in the optimized group (n=20) and 28.5±7.0 mm Hg in the ETCO2-directed group (n=20; P=0.02). Despite higher ETCO2 and mean arterial pressure in the latter group, ROSC rates were similar: 13 of 20 (65%; optimized) and 14 of 20 (70%; ETCO2 directed). The best predictor of ROSC was systemic perfusion pressure. Defibrillation attempts, epinephrine doses required, and CPR-related injuries were similar between groups. The use of ETCO2-directed chest compressions is a novel guided approach to resuscitation that can be as effective as standard CPR optimized with marker, video, and verbal feedback.

  9. Hjertestopbehandling. Nyere aspekter af kardiopulmonal genoplivning

    DEFF Research Database (Denmark)

    Herlevsen, Per Ove; Andersen, H H; Jepsen, S

    1989-01-01

    compression and increase survival. Cardiac arrest results in anaerobic metabolism and combined metabolic and respiratory acidosis. On account of relatively low minute volume during external cardiac compression decrease in end-tidal carbon dioxide concentration is observed together with arterial alkalosis...

  10. Agreement between arterial partial pressure of carbon dioxide and saturation of hemoglobin with oxygen values obtained by direct arterial blood measurements versus noninvasive methods in conscious healthy and ill foals.

    Science.gov (United States)

    Wong, David M; Alcott, Cody J; Wang, Chong; Bornkamp, Jennifer L; Young, Jessica L; Sponseller, Brett A

    2011-11-15

    To determine agreement between indirect measurements of end-tidal partial pressure of carbon dioxide (PetCO(2)) and saturation of hemoglobin with oxygen as measured by pulse oximetry (SpO(2)) with direct measurements of PaCO(2) and calculated saturation of hemoglobin with oxygen in arterial blood (SaO(2)) in conscious healthy and ill foals. Validation study. 10 healthy and 21 ill neonatal foals. Arterial blood gas analysis was performed on healthy and ill foals examined at a veterinary teaching hospital to determine direct measurements of PaCO(2) and PaO(2) along with SaO(2). Concurrently, PetCO(2) was measured with a capnograph inserted into a naris, and SpO(2) was measured with a reflectance probe placed at the base of the tail. Paired values were compared by use of Pearson correlation coefficients, and level of agreement was assessed with the Bland-Altman method. Mean ± SD difference between PaCO(2) and PetCO(2) was 0.1 ± 5.0 mm Hg. There was significant strong correlation (r = 0.779) and good agreement between PaCO(2) and PetCO(2). Mean ± SD difference between SaO(2) and SpO(2) was 2.5 ± 3.5%. There was significant moderate correlation (r = 0.499) and acceptable agreement between SaO(2) and SpO(2). Both PetCO(2) obtained by use of nasal capnography and SpO(2) obtained with a reflectance probe are clinically applicable and accurate indirect methods of estimating and monitoring PaCO(2) and SaO(2) in neonatal foals. Indirect methods should not replace periodic direct measurement of corresponding parameters.

  11. 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.

  12. North American coastal carbon stocks and exchanges among the coupled ecosystems of tidal wetlands and estuaries

    Science.gov (United States)

    Windham-Myers, L.; Cai, W. J.

    2017-12-01

    The development of the 2nd State of the Carbon Cycle Report (SOCCR-2) has recognized a significant role of aquatic ecosystems, including coastal zones, in reconciling some of the gaps associated with the North American carbon (C) budget. Along with a large community of coauthors, we report major C stocks and fluxes for tidal wetlands and estuaries of Canada, Mexico and the United States. We find divergent patterns between these coupled ecosystems, with tidal wetlands largely serving as CO2 sinks (net autotrophic), and open-water estuaries largely serving as CO2 sources (net heterotrophic). We summarized measurements across 4 continental regions - East Coast, Gulf of Mexico, West Coast, and High Latitudes - to assess spatial variability and datagaps in our understanding of coastal C cycling. Subtracting estuarine outgassing of 10 ± 10 Tg C yr-1 from the tidal wetland uptake of 23 ± 10 Tg C yr-1 leaves a net uptake of the combined system of 13 ± 14 Tg C yr-1. High uncertainty for net atmospheric C exchange in this combined coastal system is further complicated by spatially and temporally dynamic boundaries, as well as terrestrial C sources. Tidal wetlands are among the most productive ecosystems on earth and are capable of continuously accumulating organic C in their sediments as a result of environmental conditions that inhibit organic matter decomposition. Estuaries have more interannual variability in C dynamics than those of tidal wetlands, reflecting the estuarine balance of exchanges with terrestrial watersheds, tidal wetlands, and the continental shelf. Whereas tidal, subtidal and estuarine maps are of limited accuracy at larger scales, North America likely represents less than 1/10 of global distributions of coastal wetland habitats. Coupled land-ocean C flux models are increasingly robust but lacking much of the data needed for parameterization and validation. Accurate boundary maps and synoptic monitoring data on air-water CO2 exchange may be developed

  13. Color Doppler evaluation of the ocular arterial flow changes in chronic obstructive pulmonary disease

    International Nuclear Information System (INIS)

    Ozer, Tulay; Altin, Remzi; Ugurbas, Suat Hayri; Ozer, Yetkin; Mahmutyazicioglu, Kamran; Kart, Levent

    2006-01-01

    Purpose: To evaluate the hemodynamic changes in the extraocular orbital vessels of the patients with chronic obstructive pulmonary disease (COPD), using color Doppler ultrasonography (CDU) technique, and to compare the results with those of healthy control subjects. Methods: Forty-five patients with COPD and 17 healthy control subjects were included in this study. Patients with COPD were classified according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Fifteen patients of stage I COPD (mild airflow limitation), stage II COPD (worsening airflow limitation) or stage III COPD (severe airflow limitation) were enrolled into Group I, II and III, respectively. End tidal carbon dioxide (EtCO 2 ), peripheral oxygen saturation (SpO 2 ), pulse rate (PR) and respiratory rate (RR) were measured by using capnograph/pulse oximeter in all patients. Measurements were performed in only one randomly chosen eye of each participant. The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index (RI) were measured in the ophthalmic artery (OA), central retinal artery (CRA), lateral short posterior ciliary artery (LPCA) and medial short posterior ciliary artery (MPCA), using CDU technique. Results: The PSV measurements of the OA were significantly higher in Groups II and III compared to control group (p 2 with PSV (r = 0.53, p < 0.01) and EDV (r = 0.51, p < 0.01) of the OA. Statistically significant correlations were also found for the SpO2 with RI (r = -0.34, p < 0.05) in the OA. Conclusion: We concluded that COPD is associated with impaired retrobulbar hemodynamics, especially in the ophthalmic artery. Moreover, central retinal and posterior ciliary arteries with increased resistance are also found to be affected when compared with healthy control eyes

  14. Predictive value of EndTidalCO2, lung mechanics and other standard parameters for weaning neurological patients from mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Hala A. Mohammad

    2016-01-01

    Conclusion: We concluded that measurements of RSBI, MIP (maximum inspiratory pressure, EndTidalCO2 and dynamic compliance were more accurate predictors of extubation failure in patients with neurological insults than other standard weaning parameters.

  15. Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm.

    Science.gov (United States)

    Dix, Laura Marie Louise; Weeke, Lauren Carleen; de Vries, Linda Simone; Groenendaal, Floris; Baerts, Willem; van Bel, Frank; Lemmers, Petra Maria Anna

    2017-08-01

    To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO 2 (etCO 2 ) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO 2 fluctuations of ≥5  mm Hg. Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO 2 increase and 70 episodes of etCO 2 decrease. During etCO 2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P carbon dioxide partial pressure that may be harmful to the neonatal brain. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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.

  17. Positive end expiratory pressure during one-lung ventilation: Selecting ideal patients and ventilator settings with the aim of improving arterial oxygenation

    Directory of Open Access Journals (Sweden)

    Hoftman Nir

    2011-01-01

    Full Text Available The efficacy of positive end-expiratory pressure (PEEP in treating intraoperative hypoxemia during one-lung ventilation (OLV remains in question given conflicting results of prior studies. This study aims to (1 evaluate the efficacy of PEEP during OLV, (2 assess the utility of preoperative predictors of response to PEEP, and (3 explore optimal intraoperative settings that would maximize the effects of PEEP on oxygenation. Forty-one thoracic surgery patients from a single tertiary care university center were prospectively enrolled in this observational study. After induction of general anesthesia, a double-lumen endotracheal tube was fiberoptically positioned and OLV initiated. Intraoperatively, PEEP = 5 and 10 cmH 2 O were sequentially applied to the ventilated lung during OLV. Arterial oxygenation, cardiovascular performance parameters, and proposed perioperative variables that could predict or enhance response to PEEP were analysed. T-test and c2 tests were utilized for continuous and categorical variables, respectively. Multivariate analyses were carried out using a classification tree model of binary recursive partitioning. PEEP improved arterial oxygenation by ≥20% in 29% of patients (n = 12 and failed to do so in 71% (n = 29; however, no cardiovascular impact was noted. Among the proposed clinical predictors, only intraoperative tidal volume per kilogram differed significantly between responders to PEEP and non-responders (mean 6.6 vs. 5.7 ml/kg, P = 0.013; no preoperative variable predicted response to PEEP. A multivariate analysis did not yield a clinically significant model for predicting PEEP responsiveness. PEEP improved oxygenation in a subset of patients; larger, although still protective tidal volumes favored a positive response to PEEP. No preoperative variables, however, could be identified as reliable predictors for PEEP responders.

  18. Colorimetric end-tidal CO2 detector for verification of endotracheal tube placement in out-of-hospital cardiac arrest.

    Science.gov (United States)

    Hayden, S R; Sciammarella, J; Viccellio, P; Thode, H; Delagi, R

    1995-06-01

    To evaluate the ability of a disposable, colorimetric end-tidal CO2 detector to verify proper endotracheal (ET) tube placement in out-of-hospital cardiac arrest, and to correlate semiquantitative CO2 measurements with the rate of return of spontaneous circulation (ROSC). Prospective, observational study using a convenience sample of intubated out-of-hospital cardiac arrest patients. A disposable, colorimetric end-tidal CO2 detector was attached to the ET tube after intubation. In the absence of a colorimetric change, the paramedics reassessed the tube placement and could reintubate the patient. Tube placement was verified at the hospital. Paramedics were instructed to contact the base station and report the colorimetric change upon hospital arrival. ROSC was defined as restoration of a self-sustaining pulse until hospital arrival. Between December 1990 and May 1993, ET tubes were placed in 566 victims of out-of-hospital cardiac arrest. 541 of the 566 intubations (95.6%) were associated with a color change. In one case with a color change and out-of-hospital clinical evidence of proper tube placement, the tube was determined to be in the esophagus at the hospital. Correct placement of the remaining 565 of 566 (99.8%) tubes was verified. Of the 566 patients who had a colorimetric change, 91 (16%) had ROSC vs one of 25 (4%) patients who did not have a color change. In one subgroup (n = 179), the degree of color change was highly associated with ROSC (p = 0.004). A disposable, colorimetric end-tidal CO2 detector appears reliable in verifying proper ET tube placement in victims of out-of-hospital cardiac arrest. The degree of color change correlates with the probability of ROSC.

  19. 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

  20. Usefulness of end-tidal carbon dioxide as an indicator of dehydration in pediatric emergency departments: A retrospective observational study.

    Science.gov (United States)

    Yang, Hee Won; Jeon, Woochan; Min, Young Gi; Lee, Ji Sook

    2017-09-01

    Physician assessment of hydration status is one of the most important factors in the management of dehydration in the pediatric emergency department (ED). Overestimating dehydration may lead to overtreatment with intravenous fluids or unnecessary hospitalization, whereas underestimation may lead to delayed therapy and aggravation of symptoms. Various methods to estimate hydration status have been proposed, including use of physical findings, body weight, and laboratory results. These methods are subjective, invasive, or inappropriate for application in the ED. A few studies have investigated the use of end-tidal carbon dioxide (ETCO2) as an acidosis parameter in cases of gastroenteritis and diabetic ketoacidosis. We aimed to evaluate the usefulness of ETCO2 as an objective and noninvasive dehydration parameter for children.A retrospective observational study was conducted in the regional emergency center of a tertiary university hospital for a period of 1 year. We included patients from the ED whose primary diagnosis was acute gastroenteritis. Among these, we enrolled patients with recorded ETCO2 and bicarbonate concentration (HCO3) levels. We collected information of clinical characteristics, vital signs, clinical dehydration scale (CDS) scores, laboratory test results, and final disposition. Correlations between ETCO2 and HCO3 as well as CDS scores were analyzed.A total of 105 children were finally enrolled in the study. All participants underwent laboratory testing and were mildly to severely dehydrated, with mean serum HCO3 20.7 ± 3.5 mmol/L. A total 95 (90.5%) patients had a CDS score dehydration, and 10 (9.5%) patients had CDS ≥5, considered moderate-to-severe dehydration. The mean ETCO2 level was 32.1 ± 6.1 mmHg. Pearson correlation indicated a weak link between ETCO2 and HCO3 (correlation coefficient = 0.32), despite being statistically significant (P = .001). In addition, ETCO2 and CDS score showed a weak negative correlation (r

  1. Tidal Power in the UK and Worldwide to Reduce Greenhouse Gas Emissions

    Directory of Open Access Journals (Sweden)

    T. J. Hammons

    2011-05-01

    Full Text Available This paper discusses the role of Tidal Power in the UK in fulfilling the UK's requirements for reducing greenhouse gas emissions. Generating electricity from tidal range of the Severn Estuary has the potential to generate some 5% of UK electricity from a renewable indigenous resource. The paper focuses primarily on the proposed Severn Barrage considering potential benefits, conditions for sustainable development, energy policy context and compliance with environment legislation. UK tidal resource is reviewed: stream resource (that is KE contained in fast-flowing tidal currents, and tidal range resource (that refers to gravitation potential energy. The top tidal range and tidal stream sites in the UK with the resource (in TWh/year are indicated. A feasibility study for Tidal Range development in the Mersey Estuary is also summarised and other schemes including the Loughor Estuary (Wales, Duddon Estuary (located on the Cumbrian coast and the Thames Estuary proposals are reported. Also given is a strategic overview of the Severn Estuary resource, electric output and characteristics, carbon emissions (carbon payback and carbon reduction potential and physical implications of a barrage.

  2. Tidal Marshes as Pulsing Systems: New Estimates of Marsh-Carbon Export and Fate

    Science.gov (United States)

    Logozzo, L. A.; Neale, P.; Tzortziou, M.; Nelson, N.; Megonigal, P.

    2016-02-01

    We investigated wetland-estuarine exchanges of dissolved organic carbon (DOC), chromophoric dissolved organic matter (CDOM), dissolved inorganic carbon (DIC), and chlorophyll a (chl a) in the Chesapeake Bay Kirkpatrick wetlands, an ecosystem that is representative of brackish marshes with organic-rich soils in North America. 1 L water samples were collected every hour over multiple semidiurnal tidal cycles (24 h deployments) and the flow was continuously measured every minute over the course of the study. DIC samples were collected and filtered on site. Fluxes were estimated using the measured flow and concentrations of biogeochemical variables (DOC, DIC, and chl a as a measure of algal biomass). aCDOM(300) was used as a proxy for CDOM amount to observe variations over two semidiurnal tidal cycles. Relative to high tide water, low tide water was consistently enriched in DOC, DIC, and CDOM, whereas it was consistently depleted in chl a. Initial estimates of fluxes over the tidal cycle showed net export of DIC and DOC from the marsh, and net import of chl a into the marsh. These results are consistent with DOC flux estimates from previous studies, but our method utilizes high temporal resolution flow measurements, improving flux estimate accuracy. Transect sampling from the marsh into the sub-estuary during ebbing tide indicated a strong negative gradient in a­CDOM­(300) and non-conservative mixing with salinity. The observed gradients in CDOM absorption spectral shape (slope and slope ratios) and the relative changes in the major fluorescence components identified in 3D fluorescence excitation-emission-matrices, indicated strong photochemical degradation in the estuary and a shift from higher to lower molecular-weight organic compounds. The weaker gradients observed for DOC and DIC compared to aCDOM(300) indicate that while microbial degradation does occur, photobleaching is the dominant degradation mechanism for CDOM in the estuary.

  3. Organic Carbon and Trace Element Cycling in a River-Dominated Tidal Coastal Wetland System (Tampa Bay, FL, USA)

    Science.gov (United States)

    Moyer, R. P.; Smoak, J. M.; Engelhart, S. E.; Powell, C. E.; Chappel, A. R.; Gerlach, M. J.; Kemp, A.; Breithaupt, J. L.

    2016-02-01

    Tampa Bay is the largest open water, river-fed estuary in Florida (USA), and is characterized by the presence of both mangrove and salt marsh ecosystems. Both coastal wetland systems, and small rivers such as the ones draining into Tampa Bay have historically been underestimated in terms of their role in the global carbon and elemental cycles. Climate change and sea-level rise (SLR) are major threats in Tampa Bay and stand to disrupt hydrologic cycles, compromising sediment accumulation and the rate of organic carbon (OC) burial. This study evaluates organic carbon content, sediment accumulation, and carbon burial rates in salt marsh and mangrove ecosystems, along with measurements of fluxes of dissolved OC (DOC) and trace elements in the water column of the Little Manatee River (LMR) in Tampa Bay. The characterization of OC and trace elements in tidal rivers and estuaries is critical for quantitatively constraining these systems in local-to-regional scale biogeochemical budgets, and provide insight into biogeochemical processes occurring with the estuary and adjacent tidal wetlands. Material fluxes of DOC and trace elements were tied to discharge irrespective of season, and the estuarine habitats removed 15-65% of DOC prior to export to Tampa Bay and the Gulf of Mexico. Thus, material is available for cycling and burial within marsh and mangrove peats, however, LMR mangrove peats have higher OC content and burial rates than adjacent salt marsh peats. Sedimentary accretion rates in LMR marshes are not currently keeping pace with SLR, thus furthering the rapid marsh-to-mangrove conversions that have been seen in Tampa Bay over the past half-century. Additionally, wetlands in Tampa Bay tend to have a lower rate of carbon burial than other Florida tidal wetlands, demonstrating their high sensitivity to climate change and SLR.

  4. Seasonality and flux estimates of dissolved organic carbon in tidal wetlands and estuaries in the U.S. Mid- Atlantic Bight and Gulf of Mexico from ocean color

    Science.gov (United States)

    Cao, F.; Tzortziou, M.; Hu, C.; Najjar, R.

    2016-02-01

    Tidal wetlands and estuaries are dynamic features of coastal ocean and play critical roles in the global carbon cycle. Exchanges of dissolved organic carbon (DOC) between tidal wetlands and adjacent estuaries have important implications for carbon sequestration in tidal wetlands as well as biogeochemical cycling of wetlands derived material in the coastal zones. Recent studies demonstrated that the absorption coefficients of chromophoric dissolved organic matter at λ= 275 and 295 nm, which can be derived from satellite ocean color observations, can be used to accurately retrieve dissolved organic carbon (DOC) in some coastal waters. Based on a synthesis of existing field observations collected covering wide spatial and temporal variability in the Mid-Atlantic Bight and the Gulf of Mexico, here we developed and validated new empirical models to estimate coastal DOC from remotely sensed bio-optical properties of the surface water. We focused on the interfaces between tidal wetland-estuary and estuary-shelf water domains. The DOC algorithms were applied to SeaWiFs and MODIS observations to generate long-term climatological DOC distributions from 1998 to 2014. Empirical orthogonal function analysis revealed strong seasonality and spatial gradients in the satellite retrieved DOC in the tidal wetlands and estuaries. Combined with field observations and biogeochemical models, satellite retrievals can be used to scale up carbon fluxes from individual marshes and sub-estuaries to the whole estuarine system, and improve understanding of biogeochemical exchanges between terrestrial and aquatic ecosystems.

  5. Estimation of Individual-specific Progression to Impending Cardiovascular Instability using Arterial Waveforms

    Science.gov (United States)

    2013-08-08

    electrocardiogram, respiratory rate, pulse oximetry). As a result, many clinicians have wrongly assumed that hypotension and other signs and symptoms of...loss during the early com- pensatory phase of hemorrhage can quickly lead to poor tissue perfusion, progressive acidosis , and sudden, unexpected hemo...arterial blood (SpO2) was measured by standard pulse oximetry. Respiratory rate and end-tidal CO2 were measured from a nasal CO2 capnograph. With the

  6. The role of the upper tidal estuary in wetland blue carbon storage and flux

    Science.gov (United States)

    Krauss, Ken W.; Noe, Gregory B.; Duberstein, Jamie A.; Conner, William H.; Stagg, Camille L.; Cormier, Nicole; Jones, Miriam C.; Bernhardt, Christopher E.; Lockaby, B. Graeme; From, Andrew S.; Doyle, Thomas W.; Day, Richard H.; Ensign, Scott H.; Pierfelice, Katherine N.; Hupp, Cliff R.; Chow, Alex T.; Whitbeck, Julie L.

    2018-01-01

    Carbon (C) standing stocks, C mass balance, and soil C burial in tidal freshwater forested wetlands (TFFW) and TFFW transitioning to low‐salinity marshes along the upper estuary are not typically included in “blue carbon” accounting, but may represent a significant C sink. Results from two salinity transects along the tidal Waccamaw and Savannah rivers of the US Atlantic Coast show total C standing stocks were 321‐1264 Mg C ha‐1 among all sites, generally shifting to greater soil storage as salinity increased. Carbon mass balance inputs (litterfall, woody growth, herbaceous growth, root growth, surface accumulation) minus C outputs (surface litter and root decomposition, gaseous C) over a period of up to 11 years were 340‐900 g C m‐2 yr‐1. Soil C burial was variable (7‐337 g C m‐2 yr‐1), and lateral C export was estimated as C mass balance minus soil C burial as 267‐849 g C m‐2yr‐1. This represents a large amount of C export to support aquatic biogeochemical transformations. Despite reduced C persistence within emergent vegetation, decomposition of organic matter, and higher lateral C export, total C storage increased as forests converted to marsh with salinization. These tidal river wetlands exhibited high N mineralization in salinity‐stressed forested sites and considerable P mineralization in low salinity marshes. Large C standing stocks and rates of C sequestration suggest that TFFW and oligohaline marshes are considerably important globally to coastal C dynamics and in facilitating energy transformations in areas of the world in which they occur.

  7. 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.

  8. Presence of calcium in the vessel walls after end-to-end arterial anastomoses with polydioxanone and polypropylene sutures in growing dogs.

    Science.gov (United States)

    Gersak, B

    1993-10-01

    The presence of calcium in the vessel walls after end-to-end arterial anastomoses performed with polydioxanone and polypropylene interrupted sutures was studied in 140 anastomoses in 35 10-week-old German shepherd dogs. Histologic examination with hematoxylin and eosin, van Gieson, and von Kossa staining techniques was performed after the animals were killed 6 months after the operation. Ketamine hydrochloride was used as an anesthetic agent. At the start of the investigation the dogs weighed 14.5 +/- 2.6 kg (mean +/- standard deviation, n = 35), and after 6 months they weighed 45.3 +/- 3.1 kg (mean +/- standard deviation, n = 35). The diameter of the sutured arteries in the first operation was 2.6 +/- 0.5 mm (mean +/- standard deviation, n = 140). With each dog, both brachial and both femoral arteries were used--one artery for each different type of suture. In different dogs, different arteries were used for the same type of suture. The prevalence of calcifications after 6 months was determined from the numeric density of calcifications with standard stereologic techniques. The sutured and sutureless parts taken from longitudinal sections from each artery were studied, and t test values were calculated as follows: In paired samples, statistically significant differences in numerical density of calcifications were seen between sutured and sutureless arterial parts for both materials (sutureless part versus part with polydioxanone sutures, p 0.05, n = 70) and sutureless parts (p > 0.05, n = 70).

  9. 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...

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

    Science.gov (United States)

    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.

  11. 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

  12. Local and regional scale exchanges of dissolved organic carbon (DOC) between tidal wetlands and their adjacent coastal waters

    Science.gov (United States)

    Osburn, C. L.; Joshi, I.; Lebrasse, M. C.; Oviedo-Vargas, D.; Bianchi, T. S.; Bohnenstiehl, D. R.; D'Sa, E. J.; He, R.; Ko, D.; Arellano, A.; Ward, N. D.

    2017-12-01

    The contribution of blue carbon from tidal wetlands to the coastal ocean in the form of dissolved organic carbon (DOC) represents a terrestrial-aquatic linkage of increasing importance. DOC flux results will be presented from local (tidal creek) and regional (bays) scale studies in which various combinations of field observations, ocean-color satellite observations, and the outputs of high-resolution hydrodynamic models were used to estimate DOC export. The first project was located in Bald Head Creek, a tributary to the Cape Fear River estuary in eastern North Carolina (NC). DOC fluxes were computed using a bathymetric data collected via unmanned surface vehicle (USV) and a numerical hydrodynamic model (SCHISM) based on the relationships between colored dissolved organic matter (CDOM) absorption, DOC concentration, and salinity taken from field observations. Model predictions estimated an annual net export of DOC at 54 g C m-2 yr-1 from the tidal creek to the adjacent estuary. Carbon stable isotope (δ13C) values were used to estimate the contribution of wetland carbon to this export. In the second project, DOC fluxes from the Apalachicola Bay, FL, Barataria Bay, LA, were based on the development of algorithms between DOC and CDOM absorption derived from the VIIRS ocean color sensor. The Navy Coastal Ocean Model (NCOM) was used to compute salt flux estimates from each bay to the Louisiana-Texas shelf. The relationship between salinity and CDOM was used to estimate net annual DOC exports of 8.35 x 106 g C m-2 y-1 (Apalachicola Bay) and 7.14 x 106 g C m-2 yr-1 (Barataria Bay). These values approximate 13% and 9% of the annual loads of DOC from the Mississippi River to the Gulf of Mexico, respectively. CDOM and lignin were used in a mixing model to estimate wetland-derived DOC were 2% for Apalachicola Bay and 13% for Barataria Bay, the latter having one of the highest rates of relative sea level rise in North America. Results from our project demonstrated the utility

  13. Spatial patterns in salt marsh porewater dissolved organic matter over a spring-neap tidal cycle: insight to the impact of hydrodynamics on lateral carbon fluxes

    Science.gov (United States)

    Guimond, J. A.; Yu, X.; Duque, C.; Michael, H. A.

    2016-12-01

    Salt marshes are a hydrologically complex ecosystem. Tides deliver saline surface water to salt marshes via tidal creeks, and freshwater is introduced through lateral groundwater flow and vertical infiltration from precipitation. Locally, sediment heterogeneity, tides, weather, and topography introduce spatial and temporal complexities in groundwater-surface water interactions, which, in turn, can have a large impact on salt marsh biogeochemistry and the lateral fluxes of nutrients and carbon between the marsh platform and tidal creek. In this study, we investigate spatial patterns of porewater fluorescent dissolved organic matter (fDOM) and redox potential over a spring-neap tidal cycle in a mid-latitude tidal salt marsh in Dover, Delaware. Porewater samplers were used in conjunction with a peristaltic pump and YSI EXO Sonde to measure porewater fDOM, electrical conductivity, redox potential and pH from 0.5, 1.0, 1.5, 2.0, and 2.3 meters deep, as well as surface water from the creek and marsh platform. Eh was also measured continuously every 15 minutes with multi-level in-situ redox sensors at 0, 3, and 5m from the tidal creek, and water level and salinity were measured every 15 minutes continuously in 6 wells equipped with data loggers. Preliminary analyses indicate porewater salinity is dependent on the slope of the marsh platform, the elevation of the sample location, and the distance from a tidal creek. Near-creek redox analyses show tidal oscillations up to 300 mV; redox oscillations in the marsh interior show longer timescale changes. The observed redox oscillations coincide with the water level fluctuations at these locations. Therefore, lateral transport of carbon is determined by both hydrologic flow and biogeochemical processes. Results from this study provide insight into the timescales over which salt marsh hydrology impacts porewater biogeochemistry and the mechanisms controlling regional carbon cycling.

  14. Cerebral blood flow response to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in children

    International Nuclear Information System (INIS)

    Kern, F.H.; Ungerleider, R.M.; Quill, T.J.; Baldwin, B.; White, W.D.; Reves, J.G.; Greeley, W.J.

    1991-01-01

    We examined the relationship of changes in partial pressure of carbon dioxide on cerebral blood flow responsiveness in 20 pediatric patients undergoing hypothermic cardiopulmonary bypass. Cerebral blood flow was measured during steady-state hypothermic cardiopulmonary bypass with the use of xenon 133 clearance methodology at two different arterial carbon dioxide tensions. During these measurements there was no significant change in mean arterial pressure, nasopharyngeal temperature, pump flow rate, or hematocrit value. Cerebral blood flow was found to be significantly greater at higher arterial carbon dioxide tensions (p less than 0.01), so that for every millimeter of mercury rise in arterial carbon dioxide tension there was a 1.2 ml.100 gm-1.min-1 increase in cerebral blood flow. Two factors, deep hypothermia (18 degrees to 22 degrees C) and reduced age (less than 1 year), diminished the effect carbon dioxide had on cerebral blood flow responsiveness but did not eliminate it. We conclude that cerebral blood flow remains responsive to changes in arterial carbon dioxide tension during hypothermic cardiopulmonary bypass in infants and children; that is, increasing arterial carbon dioxide tension will independently increase cerebral blood flow

  15. Percutaneous coronary revascularization in patients with formerly "refractory angina pectoris in end-stage coronary artery disease" – Not "end-stage" after all

    Directory of Open Access Journals (Sweden)

    Khattab Ahmed A

    2009-08-01

    Full Text Available Abstract Background Patients with refractory angina pectoris in end-stage coronary artery disease represent a severe condition with a higher reduction of life-expectancy and quality of life as compared to patients with stable coronary artery disease. It was the purpose of this study to invasively re-evaluate highly symptomatic patients with formerly diagnosed refractory angina pectoris in end-stage coronary artery disease for feasible options of myocardial revascularization. Methods Thirty-four Patients formerly characterized as having end stage coronary artery disease with refractory angina pectoris were retrospectively followed for coronary interventions. Results Of those 34 patients 21 (61.8% were eventually revascularized with percutaneous interventional revascularization (PCI. Due to complex coronary morphology (angulation, chronic total occlusion PCI demanded an above-average amount of time (66 ± 42 minutes, range 25–206 minutes and materials (contrast media 247 ± 209 ml, range 50–750 ml; PCI guiding wires 2.0 ± 1.4, range 1–6 wires. Of PCI patients 7 (33.3% showed a new lesion as a sign of progression of atherosclerosis. Clinical success rate with a reduction to angina class II or lower was 71.4% at 30 days. Surgery was performed in a total of8 (23.5% patients with a clinical success rate of 62.5%. Based on an intention-to-treat 2 patients of originally 8 (25% demonstrated clinical success. Mortality during follow-up (1–18 months was 4.8% in patients who underwent PCI, 25% in patients treated surgically and 25% in those only treated medically. Conclusion The majority of patients with end-stage coronary artery disease can be treated effectively with conventional invasive treatment modalities. Therefore even though it is challenging and demanding PCI should be considered as a first choice before experimental interventions are considered.

  16. Ecosystem level methane fluxes from tidal freshwater and brackish marshes of the Mississippi River Delta: Implications for coastal wetland carbon projects

    Science.gov (United States)

    Holm, Guerry O.; Perez, Brian C.; McWhorter, David E.; Krauss, Ken W.; Johnson, Darren J.; Raynie, Richard C.; Killebrew, Charles J.

    2016-01-01

    Sulfate from seawater inhibits methane production in tidal wetlands, and by extension, salinity has been used as a general predictor of methane emissions. With the need to reduce methane flux uncertainties from tidal wetlands, eddy covariance (EC) techniques provide an integrated methane budget. The goals of this study were to: 1) establish methane emissions from natural, freshwater and brackish wetlands in Louisiana based on EC; and 2) determine if EC estimates conform to a methane-salinity relationship derived from temperate tidal wetlands with chamber sampling. Annual estimates of methane emissions from this study were 62.3 g CH4/m2/yr and 13.8 g CH4/m2/yr for the freshwater and brackish (8–10 psu) sites, respectively. If it is assumed that long-term, annual soil carbon sequestration rates of natural marshes are ~200 g C/m2/yr (7.3 tCO2e/ha/yr), healthy brackish marshes could be expected to act as a net radiative sink, equivalent to less than one-half the soil carbon accumulation rate after subtracting methane emissions (4.1 tCO2e/ha/yr). Carbon sequestration rates would need case-by-case assessment, but the EC methane emissions estimates in this study conformed well to an existing salinity-methane model that should serve as a basis for establishing emission factors for wetland carbon offset projects.

  17. A blue carbon soil database: Tidal wetland stocks for the US National Greenhouse Gas Inventory

    Science.gov (United States)

    Feagin, R. A.; Eriksson, M.; Hinson, A.; Najjar, R. G.; Kroeger, K. D.; Herrmann, M.; Holmquist, J. R.; Windham-Myers, L.; MacDonald, G. M.; Brown, L. N.; Bianchi, T. S.

    2015-12-01

    Coastal wetlands contain large reservoirs of carbon, and in 2015 the US National Greenhouse Gas Inventory began the work of placing blue carbon within the national regulatory context. The potential value of a wetland carbon stock, in relation to its location, soon could be influential in determining governmental policy and management activities, or in stimulating market-based CO2 sequestration projects. To meet the national need for high-resolution maps, a blue carbon stock database was developed linking National Wetlands Inventory datasets with the USDA Soil Survey Geographic Database. Users of the database can identify the economic potential for carbon conservation or restoration projects within specific estuarine basins, states, wetland types, physical parameters, and land management activities. The database is geared towards both national-level assessments and local-level inquiries. Spatial analysis of the stocks show high variance within individual estuarine basins, largely dependent on geomorphic position on the landscape, though there are continental scale trends to the carbon distribution as well. Future plans including linking this database with a sedimentary accretion database to predict carbon flux in US tidal wetlands.

  18. 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.

  19. 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...

  20. Atmospheric carbon injection linked to end-Triassic mass extinction.

    Science.gov (United States)

    Ruhl, Micha; Bonis, Nina R; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S; Kürschner, Wolfram M

    2011-07-22

    The end-Triassic mass extinction (~201.4 million years ago), marked by terrestrial ecosystem turnover and up to ~50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5 per mil negative excursion, coincident with the extinction interval. These data indicate strong carbon-13 depletion of the end-Triassic atmosphere, within only 10,000 to 20,000 years. The magnitude and rate of this carbon-cycle disruption can be explained by the injection of at least ~12 × 10(3) gigatons of isotopically depleted carbon as methane into the atmosphere. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence, end-Triassic events are robustly linked to methane-derived massive carbon release and associated climate change.

  1. 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.

  2. Mutagenic effects of carbon ions near the range end in plants

    Energy Technology Data Exchange (ETDEWEB)

    Hase, Yoshihiro, E-mail: hase.yoshihiro@jaea.go.jp [Ion Beam Mutagenesis Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Yoshihara, Ryouhei; Nozawa, Shigeki; Narumi, Issay [Ion Beam Mutagenesis Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2012-03-01

    To gain insight into the mutagenic effects of accelerated heavy ions in plants, the mutagenic effects of carbon ions near the range end (mean linear energy transfer (LET): 425 keV/{mu}m) were compared with the effects of carbon ions penetrating the seeds (mean LET: 113 keV/{mu}m). Mutational analysis by plasmid rescue of Escherichia coli rpsL from irradiated Arabidopsis plants showed a 2.7-fold increase in mutant frequency for 113 keV/{mu}m carbon ions, whereas no enhancement of mutant frequency was observed for carbon ions near the range end. This suggested that carbon ions near the range end induced mutations that were not recovered by plasmid rescue. An Arabidopsis DNA ligase IV mutant, deficient in non-homologous end-joining repair, showed hyper-sensitivity to both types of carbon-ion irradiation. The difference in radiation sensitivity between the wild type and the repair-deficient mutant was greatly diminished for carbon ions near the range end, suggesting that these ions induce irreparable DNA damage. Mutational analysis of the Arabidopsis GL1 locus showed that while the frequency of generation of glabrous mutant sectors was not different between the two types of carbon-ion irradiation, large deletions (>{approx}30 kb) were six times more frequently induced by carbon ions near the range end. When 352 keV/{mu}m neon ions were used, these showed a 6.4 times increase in the frequency of induced large deletions compared with the 113 keV/{mu}m carbon ions. We suggest that the proportion of large deletions increases with LET in plants, as has been reported for mammalian cells. The nature of mutations induced in plants by carbon ions near the range end is discussed in relation to mutation detection by plasmid rescue and transmissibility to progeny.

  3. End-tidal carbon dioxide output in manual cardiopulmonary resuscitation versus active compression-decompression device during prehospital quality controlled resuscitation: a case series study.

    Science.gov (United States)

    Setälä, Piritta Anniina; Virkkunen, Ilkka Tapani; Kämäräinen, Antti Jaakko; Huhtala, Heini Sisko Annamari; Virta, Janne Severi; Yli-Hankala, Arvi Mikael; Hoppu, Sanna Elisa

    2018-05-16

    Active compression-decompression (ACD) devices have enhanced end-tidal carbon dioxide (ETCO 2 ) output in experimental cardiopulmonary resuscitation (CPR) studies. However, the results in out-of-hospital cardiac arrest (OHCA) patients have shown inconsistent outcomes, and earlier studies lacked quality control of CPR attempts. We compared manual CPR with ACD-CPR by measuring ETCO 2 output using an audiovisual feedback defibrillator to ensure continuous high quality resuscitation attempts. 10 witnessed OHCAs were resuscitated, rotating a 2 min cycle with manual CPR and a 2 min cycle of ACD-CPR. Patients were intubated and the ventilation rate was held constant during CPR. CPR quality parameters and ETCO 2 values were collected continuously with the defibrillator. Differences in ETCO 2 output between manual CPR and ACD-CPR were analysed using a linear mixed model where ETCO 2 output produced by a summary of the 2 min cycles was included as the dependent variable, the patient as a random factor and method as a fixed effect. These comparisons were made within each OHCA case to minimise confounding factors between the cases. Mean length of the CPR episodes was 37 (SD 8) min. Mean compression depth was 76 (SD 1.3) mm versus 71 (SD1.0) mm, and mean compression rate was 100 per min (SD 6.7) versus 105 per min (SD 4.9) between ACD-CPR and manual CPR, respectively. For ETCO 2 output, the interaction between the method and the patient was significant (P<0.001). ETCO 2 output was higher with manual CPR in 6 of the 10 cases. This study suggests that quality controlled ACD-CPR is not superior to quality controlled manual CPR when ETCO 2 is used as a quantitative measure of CPR effectiveness. NCT00951704; Results. © 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 expressly granted.

  4. 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

  5. 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.

  6. 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.

  7. End-tidal CO2 Detection of an Audible Heart Rate During Neonatal Cardiopulmonary Resuscitation Following Asystole in Asphyxiated Piglets

    OpenAIRE

    Chalak, Lina F.; Barber, Chad A.; Hynan, Linda; Garcia, Damian; Christie, Lucy; Wyckoff, Myra H.

    2011-01-01

    Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO2 (ETCO2) monitoring may provide a continuous non-invasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO2 value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO2 that is associated with ROSC following ...

  8. A national-scale remote sensing-based methodology for quantifying tidal marsh biomass to support "Blue Carbon" accounting

    Science.gov (United States)

    Byrd, K. B.; Ballanti, L.; Nguyen, D.; Simard, M.; Thomas, N.; Windham-Myers, L.; Castaneda, E.; Kroeger, K. D.; Gonneea, M. E.; O'Keefe Suttles, J.; Megonigal, P.; Troxler, T.; Schile, L. M.; Davis, M.; Woo, I.

    2016-12-01

    According to 2013 IPCC Wetlands Supplement guidelines, tidal marsh Tier 2 or Tier 3 accounting must include aboveground biomass carbon stock changes. To support this need, we are using free satellite and aerial imagery to develop a national scale, consistent remote sensing-based methodology for quantifying tidal marsh aboveground biomass. We are determining the extent to which additional satellite data will increase the accuracy of this "blue carbon" accounting. Working in 6 U.S. estuaries (Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA), we built a tidal marsh biomass dataset (n=2404). Landsat reflectance data were matched spatially and temporally with field plots using Google Earth Engine. We quantified percent cover of green vegetation, non-vegetation, and open water in Landsat pixels using segmentation of 1m National Agriculture Imagery Program aerial imagery. Sentinel-1A C-band backscatter data were used in Chesapeake, Mississippi Delta and Puget Sound. We tested multiple Landsat vegetation indices and Sentinel backscatter metrics in 30m scale biomass linear regression models by region. Scaling biomass by fraction green vegetation significantly improved biomass estimation (e.g. Cape Cod: R2 = 0.06 vs. R2 = 0.60, n=28). The best vegetation indices differed by region, though indices based on the shortwave infrared-1 and red bands were most predictive in the Everglades and the Mississippi Delta, while the soil adjusted vegetation index was most predictive in Puget Sound and Chesapeake. Backscatter metrics significantly improved model predictions over vegetation indices alone; consistently across regions, the most significant metric was the range in backscatter values within the green vegetation segment of the Landsat pixel (e.g. Mississippi Delta: R2 = 0.47 vs. R2 = 0.59, n=15). Results support using remote sensing of biomass stock change to estimate greenhouse gas emission factors in tidal

  9. 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

  10. Cardiorespiratory effects of isoflurane in Asiatic black bears (Ursus thibetanus) anesthetized with intramuscular medetomidine and zolazepam/tiletamine.

    Science.gov (United States)

    Jeong, Dong-Hyuk; Yang, Jeong-Jin; Seok, Seong-Hoon; Song, Dong-Joo; Yeon, Seong-Chan

    2017-01-20

    The objective of this study was to determine the dose-dependent effects of isoflurane on various cardiovascular parameters and the stable range of isoflurane concentrations in Asiatic black bears (Ursus thibetanus). Seven Asiatic black bears were intramuscularly injected with medetomidine, zolazepam and tiletamine (MZT) to induce anesthesia, and anesthesia was maintained by administering isoflurane in 100% oxygen (4 l/min) without mechanical ventilation. Several cardiovascular parameters were measured at five end-tidal isoflurane concentrations (0.5, 1.0, 1.5, 2.0, and 2.5%). Blood was collected from the femoral artery before administration of isoflurane and after each administration for immediate blood gas analysis. Isoflurane produced dose-dependent increases in heart rate, respiratory rate, minute volume, end-tidal carbon dioxide (CO 2 ) partial pressure and the partial pressure of arterial CO 2 , and dose-dependent decreases in non-invasive blood pressure and tidal volume. Rectal temperature, oxygenation and acid-base balance were unaffected by isoflurane. All parameters in this study were in a clinically acceptable range at all times. The data show that the combination of MZT and isoflurane is suitable for general anesthesia in Asiatic black bears with spontaneous breathing during prolonged procedures. End-tidal isoflurane concentrations of 0.5 to 2.5% can be used in Asiatic black bears without adverse side effects.

  11. Changes in standing stocks and fluxes of carbon due to salinization: tidal freshwater wetland forest retreat to marsh

    Science.gov (United States)

    Krauss, K.; Noe, G. B.; Duberstein, J. A.; Conner, W. H.; Stagg, C. L.; Jones, M.; Bernhardt, C. E.; Cormier, N.

    2017-12-01

    Assessments of organic carbon (C) standing stocks and fluxes as wetland ecosystems transition from tidally influenced freshwater forested wetlands to low-salinity marshes are not typically included in "blue carbon" accounting. However, these ecosystems have the potential to store and convey large quantities of C. Here, we report on data collected from eight riverine sites along salinity and hydro-edaphic gradients in South Carolina and Georgia to provide the first complete estimates of C storage, flux, and burial, including estimation of C export to aquatic environments, in tidal freshwater forested wetlands undergoing transition to oligohaline marsh. Total standing stocks of C ranged from 280 to 891 Mg C/ha along both rivers but with no consistent trend in standing stock shifts along salinity gradients between the two rivers. Soil C standing stocks were most variable among sites. Furthermore, we assessed input (litterfall, woody growth, herbaceous growth, root growth and surface sediment C accretion) in comparison with output (surface litter decomposition, root decomposition and gaseous C) fluxes over periods ranging from 2 to 11 years. C sequestration from mass balance calculations ranged from 103 to 728 g C/m2/year among sites, with generally greater C sequestration on sites with prominent salinity-mediated conversion to oligohaline marsh. Dissolved C export was estimated as the difference between C sequestration and soil C burial using 14C dating of cores, and ranged from 144 to 404 g C/m2/year, representing a large amount of C export to feed aquatic biogeochemical transformations and secondary productivity. Along with C accounting, these sites also differed in how N and P were mineralized in soils, with considerable N mineralization on salinity-stressed (2.4-4.3 parts per thousand) forested sites with newly encroached marsh plants and considerable P mineralization on slightly higher salinity marshes. In all, C storage from tidal freshwater forested wetlands

  12. 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.

  13. Arterial Stiffness and Walk Time in Patients with End-Stage Renal Disease

    Directory of Open Access Journals (Sweden)

    Abbi D. Lane

    2013-04-01

    Full Text Available Background: End-stage renal disease patients experience increased prevalence of cardiovascular disease. Heart-artery interaction may be shifted, impacting blood pressure lability, and exercise tolerance. The coupling ratio consists of the ratio of indexed arterial elastance (EaI, arterial load to ElvI, a measure of cardiac contractility or stiffness. Our purpose was to explore the relationship between elastances and functional capacity. We hypothesized that arterial stiffness (central pulse wave velocity, PWV and elastances would be correlated to shuttle walk time. Methods: We used applanation tonometry, ultrasonography, and a shuttle walk test to evaluate our hypothesis. Spearman's correlations were used to assess relationships between variables. Block regression was also performed. Results: Forty-two subjects on maintenance hemodialysis participated. Average age=44±5 years, body surface area=2.01 kg/m2. Mean EaI=4.45 and mean ElvI=6.89; the coupling ratio=0.82. Mean aortic pulse pressure=51 mmHg and PWV=9.6 m/s. PWV(r=-0.385 and EaI (r=-0.424 were significantly and inversely related to walking time while stroke volume index (SVI was positively correlated to shuttle walk time (r=0.337, pConclusions: We conclude that, like other clinical populations, both arterial and heart function predict walking ability and represent potential targets for intervention; arterial stiffness and SVI are strongly related to shuttle walk time in patients with ESRD.

  14. Impact of top end anastomosis design on patency and flow stability in coronary artery bypass grafting.

    Science.gov (United States)

    Koyama, Sachi; Kitamura, Tadashi; Itatani, Keiichi; Yamamoto, Tadashi; Miyazaki, Shohei; Oka, Norihiko; Nakashima, Kouki; Horai, Tetsuya; Ono, Minoru; Miyaji, Kagami

    2016-05-01

    For coronary artery bypass grafting (CABG), free grafts such as a saphenous vein or radial artery are often used for grafts to the lateral and posterior walls. However, the relationship between top-end anastomosis design and long-term patency remains unknown. Because coronary artery blood flow is dominant during diastole, top-end anastomosis may work better if the graft is directed towards the apex, whereas the shortest graft pathway appears to be most efficient. Using computational fluid dynamic models, we evaluated the hemodynamic variables that were affected by the angle of the top-end anastomosis. We created three-dimensional geometries of the aortic root with coronary arteries that involved 75 % stenosis in the obtuse marginal and postero-lateral branches. Two bypass models under vasodilator administration were created: in a"Model A", the top-end anastomosis is parallel to the long axis of the ascending aorta and the graft passed over the conus directed towards the apex; in a "Model B", the top-end anastomosis is directed toward the shortest pathway, and form near the right angles to the long axis of the ascending aorta. Wall shear stress (WSS) and its fluctuation, an oscillatory shear index (OSI) were evaluated to predict fibrosis progression at the anastomosis site and graft flow. Graft flow was 197.3 ml/min and 207.3 ml/min in the "Model A" and "Model B", respectively. The minimal WSS value inside the graft with the "Model A" and "Model B" was 0.53 Pa and 4.09 Pa, respectively, and the OSI value was 0.46 and 0.04, respectively. The top-end anastomosis of a free graft should be directed vertically towards the aorta to achieve the shortest graft pathway to maintain a high graft flow rate and to avoid the risks of endothelial fibrosis and plaque progression over the long-term after CABG.

  15. 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.

  16. Reversal of end-stage renal disease after aortic dissection using renal artery stent: a case report

    Directory of Open Access Journals (Sweden)

    Parikh Chirag R

    2004-05-01

    Full Text Available Abstract Background Medical management is the conventional treatment for Stanford Type B aortic dissections as surgery is associated with significant morbidity and mortality. The advent of endovascular interventional techniques has revived interest in treating end-organ complications of Type B aortic dissection. We describe a patient who benefited from endovascular repair of renal artery stenosis caused by a dissection flap, which resulted in reversal of his end-stage renal disease (ESRD. Case presentation A 69 y/o male with a Type B aortic dissection diagnosed two months earlier was found to have a serum creatinine of 15.2 mg/dL (1343.7 μmol/L on routine visit to his primary care physician. An MRA demonstrated a rightward spiraling aortic dissection flap involving the origins of the celiac artery, superior mesenteric artery, and both renal arteries. The right renal artery arose from the false lumen with lack of blood flow to the right kidney. The left renal artery arose from the true lumen, but an intimal dissection flap appeared to be causing an intermittent stenosis of the left renal artery with compromised blood flow to the left kidney. Endovascular reconstruction with of the left renal artery with stent placement was performed. Hemodialysis was successfully discontinued six weeks after stent placement. Conclusion Percutaneous intervention provides a promising alternative for patients with Type B aortic dissections when medical treatment will not improve the likelihood of meaningful recovery and surgery entails too great a risk. Nephrologists should therefore be aggressive in the workup of ischemic renal failure associated with aortic dissection as percutaneous intervention may reverse the effects of renal failure in this population.

  17. 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.

  18. 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.

  19. Is increased positive end-expiratory pressure the culprit? Autoresuscitation in a 44-year-old man after prolonged cardiopulmonary resuscitation: a case report.

    Science.gov (United States)

    Hagmann, Henning; Oelmann, Katrin; Stangl, Robert; Michels, Guido

    2016-12-20

    The phenomenon of autoresuscitation is rare, yet it is known to most emergency physicians. However, the pathophysiology of the delayed return of spontaneous circulation remains enigmatic. Among other causes hyperinflation of the lungs and excessively high positive end-expiratory pressure have been suggested, but reports including cardiopulmonary monitoring during cardiopulmonary resuscitation are scarce to support this hypothesis. We report a case of autoresuscitation in a 44-year-old white man after 80 minutes of advanced cardiac life support accompanied by continuous capnometry and repeated evaluation by ultrasound and echocardiography. After prolonged cardiopulmonary resuscitation, refractory electromechanical dissociation on electrocardiogram and ventricular akinesis were recorded. In addition, a precipitous drop in end-tidal partial pressure of carbon dioxide was noted and cardiopulmonary resuscitation was discontinued. Five minutes after withdrawal of all supportive measures his breathing resumed and a perfusing rhythm ensued. Understanding the underlying pathophysiology of autoresuscitation is hampered by a lack of reports including extensive cardiopulmonary monitoring during cardiopulmonary resuscitation in a preclinical setting. In this case, continuous capnometry was combined with repetitive ultrasound evaluation, which ruled out most assumed causes of autoresuscitation. Our observation of a rapid decline in end-tidal partial pressure of carbon dioxide supports the hypothesis of increased intrathoracic pressure. Continuous capnometry can be performed easily during cardiopulmonary resuscitation, also in a preclinical setting. Knowledge of the pathophysiologic mechanisms may lead to facile interventions to be incorporated into cardiopulmonary resuscitation algorithms. A drop in end-tidal partial pressure of carbon dioxide, for example, might prompt disconnection of the ventilation to allow left ventricular filling. Further reports and research on this topic

  20. Automatic control of arterial carbon dioxide tension in mechanically ventilated patients.

    Science.gov (United States)

    Fernando, Tyrone; Cade, John; Packer, John

    2002-12-01

    This paper presents a method of controlling the arterial carbon dioxide tension of patients receiving mechanical ventilation. Controlling of the CO2 tension is achieved by regulating the ventilator initiated breath frequency and also volume per breath.

  1. A randomized comparison of different ventilator strategies during thoracotomy for pulmonary resection.

    Science.gov (United States)

    Maslow, Andrew D; Stafford, Todd S; Davignon, Kristopher R; Ng, Thomas

    2013-07-01

    Protective lung ventilation is reported to benefit patients with acute respiratory distress syndrome. It is not known whether protective lung ventilation is also beneficial to patients undergoing single-lung ventilation for elective pulmonary resection. In an institutional review board-approved prospective randomized trial, 34 patients undergoing elective pulmonary resection requiring single-lung ventilation were enrolled. Informed consent was obtained. Patients were randomized to 1 of 2 groups: (1) high tidal volume (Hi-TV) of 10 mL/kg, rate of 7 breaths/min, and zero positive end-expiratory pressure or (2) low tidal volume (Lo-TV) of 5 mL/kg, rate of 14 breaths/min, and 5 cmH2O positive end-expiratory pressure. Ventilator settings were continued during both double- and single-lung ventilation. Pulmonary functions, hemodynamics, and postoperative outcomes were recorded. Patient demographics, operative characteristics, intraoperative hemodynamics, and postoperative pain and sedation scores were similar between the 2 groups. During most time periods, airway pressures (peak and plateau) were significantly higher in the Hi-TV group; however, plateau pressures remained less than 30 cmH2O at all times for all patients. The Hi-TV group had significantly lower arterial carbon dioxide tension, less arterial carbon dioxide tension-end-tidal carbon dioxide gradient, lower alveolar dead space ratio, and higher dynamic pulmonary compliance. There were no differences in postoperative morbidity and hospital days between the 2 groups, but atelectasis scores on postoperative days 1 and 2 were lower in the Hi-TV group. The use of Hi-TV during single-lung ventilation for pulmonary resection resulted in no increase in morbidity and was associated with less hypercarbia, less dead space ventilation, better dynamic compliance, and less postoperative atelectasis. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  2. An Introduction to the San Francisco Estuary Tidal Wetlands Restoration Series

    Directory of Open Access Journals (Sweden)

    Larry R. Brown

    2003-10-01

    Full Text Available Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter “Estuary”. Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period. However, many other changes have also occurred in the Estuary concurrent with the declines of native species. Other factors that might be important in species declines include the effects of construction of upstream dams, large and small water diversions within the Sacramento-San Joaquin Delta, agricultural pesticides, trace elements from industrial and agricultural activities, and invasions of alien species. Discussions among researchers, managers, and stakeholders have identified a number of uncertainties regarding the potential benefits of tidal wetland restoration. The articles of the Tidal Wetlands Restoration Series address four major issues of concern. Stated as questions, these are: 1. Will tidal wetland restoration enhance populations of native fishes? 2. Will wetland restoration increase rates of methylation of mercury? 3. Will primary production and other ecological processes in restored tidal wetlands result in net export of organic carbon to adjacent habitats, resulting in enhancement of the food web? Will the carbon produced contribute to the formation of disinfection byproducts when disinfected for use as drinking water? 4. Will restored tidal wetlands provide long-term ecosystem benefits that can be sustained in response to ongoing physical processes, including sedimentation and hydrodynamics? Reducing the uncertainty surrounding these issues is of critical importance because tidal wetland restoration is assumed to be a critical tool for

  3. Long-term organic carbon sequestration in tidal marsh sediments is dominated by old-aged allochthonous inputs in a macrotidal estuary.

    Science.gov (United States)

    Van de Broek, Marijn; Vandendriessche, Caroline; Poppelmonde, Dries; Merckx, Roel; Temmerman, Stijn; Govers, Gerard

    2018-02-12

    Tidal marshes are vegetated coastal ecosystems that are often considered as hotspots of atmospheric CO 2 sequestration. Although large amounts of organic carbon (OC) are indeed being deposited on tidal marshes, there is no direct link between high OC deposition rates and high OC sequestration rates due to two main reasons. First, the deposited OC may become rapidly decomposed once it is buried and, second, a significant part of preserved OC may be allochthonous OC that has been sequestered elsewhere. In this study we aimed to identify the mechanisms controlling long-term OC sequestration in tidal marsh sediments along an estuarine salinity gradient (Scheldt estuary, Belgium and the Netherlands). Analyses of deposited sediments have shown that OC deposited during tidal inundations is up to millennia old. This allochthonous OC is the main component of OC that is effectively preserved in these sediments, as indicated by the low radiocarbon content of buried OC. Furthermore, OC fractionation showed that autochthonous OC is decomposed on a decadal timescale in saltmarsh sediments, while in freshwater marsh sediments locally produced biomass is more efficiently preserved after burial. Our results show that long-term OC sequestration is decoupled from local biomass production in the studied tidal marsh sediments. This implies that OC sequestration rates are greatly overestimated when they are calculated based on short-term OC deposition rates, which are controlled by labile autochthonous OC inputs. Moreover, as allochthonous OC is not sequestered in-situ, it does not contribute to active atmospheric CO 2 sequestration in these ecosystems. A correct assessment of the contribution of allochthonous OC to the total sedimentary OC stock in tidal marsh sediments as well as a correct understanding of the long-term fate of locally produced OC are both necessary to avoid overestimations of the rate of in-situ atmospheric CO 2 sequestration in tidal marsh sediments. © 2018 John

  4. 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.

  5. 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.

  6. Heat stress redistributes blood flow in arteries of the brain during dynamic exercise.

    Science.gov (United States)

    Sato, Kohei; Oue, Anna; Yoneya, Marina; Sadamoto, Tomoko; Ogoh, Shigehiko

    2016-04-01

    We hypothesized that heat stress would decrease anterior and posterior cerebral blood flow (CBF) during exercise, and the reduction in anterior CBF would be partly associated with large increase in extracranial blood flow (BF). Nine subjects performed 40 min of semirecumbent cycling at 60% of the peak oxygen uptake in hot (35°C; Heat) and thermoneutral environments (25°C; Control). We evaluated BF and conductance (COND) in the external carotid artery (ECA), internal carotid artery (ICA), and vertebral artery (VA) using ultrasonography. During the Heat condition, ICA and VA BF were significantly increased 10 min after the start of exercise (P Heat. Compared with the Control, either BF or COND of ICA and VA at the end of Heat tended to be lower, but not significantly. In contrast, ECA BF and COND at the end of Heat were both higher than levels in the Control condition (P Heat, a reduction in ICA BF appears to be associated with a decline in end-tidal CO2 tension (r = 0.84), whereas VA BF appears to be affected by a change in cardiac output (r = 0.87). In addition, a change in ECA BF during Heat was negatively correlated with a change in ICA BF (r = -0.75). Heat stress resulted in modification of the vascular response of head and brain arteries to exercise, which resulted in an alteration in the distribution of cardiac output. Moreover, a hyperthermia-induced increase in extracranial BF might compromise anterior CBF during exercise with heat stress. Copyright © 2016 the American Physiological Society.

  7. Right Heart End-Systolic Remodeling Index Strongly Predicts Outcomes in Pulmonary Arterial Hypertension: Comparison With Validated Models.

    Science.gov (United States)

    Amsallem, Myriam; Sweatt, Andrew J; Aymami, Marie C; Kuznetsova, Tatiana; Selej, Mona; Lu, HongQuan; Mercier, Olaf; Fadel, Elie; Schnittger, Ingela; McConnell, Michael V; Rabinovitch, Marlene; Zamanian, Roham T; Haddad, Francois

    2017-06-01

    Right ventricular (RV) end-systolic dimensions provide information on both size and function. We investigated whether an internally scaled index of end-systolic dimension is incremental to well-validated prognostic scores in pulmonary arterial hypertension. From 2005 to 2014, 228 patients with pulmonary arterial hypertension were prospectively enrolled. RV end-systolic remodeling index (RVESRI) was defined by lateral length divided by septal height. The incremental values of RV free wall longitudinal strain and RVESRI to risk scores were determined. Mean age was 49±14 years, 78% were female, 33% had connective tissue disease, 52% were in New York Heart Association class ≥III, and mean pulmonary vascular resistance was 11.2±6.4 WU. RVESRI and right atrial area were strongly connected to the other right heart metrics. Three zones of adaptation (adapted, maladapted, and severely maladapted) were identified based on the RVESRI to RV systolic pressure relationship. During a mean follow-up of 3.9±2.4 years, the primary end point of death, transplant, or admission for heart failure was reached in 88 patients. RVESRI was incremental to risk prediction scores in pulmonary arterial hypertension, including the Registry to Evaluate Early and Long-Term PAH Disease Management score, the Pulmonary Hypertension Connection equation, and the Mayo Clinic model. Using multivariable analysis, New York Heart Association class III/IV, RVESRI, and log NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) were retained (χ 2 , 62.2; P right heart metrics, RVESRI demonstrated the best test-retest characteristics. RVESRI is a simple reproducible prognostic marker in patients with pulmonary arterial hypertension. © 2017 American Heart Association, Inc.

  8. Intrinsic positive end-expiratory pressure during one-lung ventilation of patients with pulmonary hyperinflation. Influence of low respiratory rate with unchanged minute volume.

    Science.gov (United States)

    Szegedi, L L; Barvais, L; Sokolow, Y; Yernault, J C; d'Hollander, A A

    2002-01-01

    We measured lung mechanics and gas exchange during one-lung ventilation (OLV) of patients with chronic obstructive pulmonary disease, using three respiratory rates (RR) and unchanged minute volume. We studied 15 patients about to undergo lung surgery, during anaesthesia, and placed in the lateral position. Ventilation was with constant minute volume, inspiratory flow and FIO2. For periods of 15 min, RR of 5, 10, and 15 bpm were applied in a random sequence and recordings were made of lung mechanics and an arterial blood gas sample was taken. Data were analysed with the repeated measures ANOVA and paired t-test with Bonferroni correction. PaO2 changes were not significant. At the lowest RR, PaCO2 decreased (from 42 (SD 4) mm Hg at RR 15-41 (4) mm Hg at RR 10 and 39 (4) mm Hg at RR 5, P<0.01), and end-tidal carbon dioxide increased (from 33 (5) mm Hg at RR 15 to 35 (5) mm Hg at RR 10 and 36 (6) mm Hg at RR 5, P<0.01). Intrinsic positive end-expiratory pressure (PEEPi) was reduced even with larger tidal volumes (from 6 (4) cm H2O at RR 15-5 (4) cm H2O at RR 10, and 3 (3) cm H2O at RR 5, P<0.01), most probably caused by increased expiratory time at the lowest RR. A reduction in RR reduces PEEPi and hypercapnia during OLV in anaesthetized patients with chronic obstructive lung disease.

  9. Functional end-arterial circulation of the choroid assessed by using fat embolism and electric circuit simulation.

    Science.gov (United States)

    Lee, Ji Eun; Ahn, Ki Su; Park, Keun Heung; Pak, Kang Yeun; Kim, Hak Jin; Byon, Ik Soo; Park, Sung Who

    2017-05-30

    The discrepancy in the choroidal circulation between anatomy and function has remained unsolved for several decades. Postmortem cast studies revealed extensive anastomotic channels, but angiographic studies indicated end-arterial circulation. We carried out experimental fat embolism in cats and electric circuit simulation. Perfusion defects were observed in two categories. In the scatter perfusion defects suggesting an embolism at the terminal arterioles, fluorescein dye filled the non-perfused lobule slowly from the adjacent perfused lobule. In the segmental perfusion defects suggesting occlusion of the posterior ciliary arteries, the hypofluorescent segment became perfused by spontaneous resolution of the embolism without subsequent smaller infarction. The angiographic findings could be simulated with an electric circuit. Although electric currents flowed to the disconnected lobule, the level was very low compared with that of the connected ones. The choroid appeared to be composed of multiple sectors with no anastomosis to other sectors, but to have its own anastomotic arterioles in each sector. Blood flows through the continuous choriocapillaris bed in an end-arterial nature functionally to follow a pressure gradient due to the drainage through the collector venule.

  10. 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.

  11. Influence of suture technique and suture material selection on the mechanics of end-to-end and end-to-side anastomoses.

    Science.gov (United States)

    Baumgartner, N; Dobrin, P B; Morasch, M; Dong, Q S; Mrkvicka, R

    1996-05-01

    Experiments were performed in dogs to evaluate the mechanics of 26 end-to-end and 42 end-to-side artery-vein graft anastomoses constructed with continuous polypropylene sutures (Surgilene; Davis & Geck, Division of American Cyanamid Co., Danbury, Conn.), continuous polybutester sutures (Novafil; Davis & Geck), and interrupted stitches with either suture material. After construction, the grafts and adjoining arteries were excised, mounted in vitro at in situ length, filled with a dilute barium sulfate suspension, and pressurized in 25 mm Hg steps up to 200 mm Hg. Radiographs were obtained at each pressure. The computed cross-sectional areas of the anastomoses were compared with those of the native arteries at corresponding pressures. Results showed that for the end-to-end anastomoses at 100 mm Hg the cross-sectional areas of the continuous Surgilene anastomoses were 70% of the native artery cross-sectional areas, the cross-sectional areas of the continuous Novafil anastomoses were 90% of the native artery cross-sectional areas, and the cross-sectional areas of the interrupted anastomoses were 107% of the native artery cross-sectional areas (p anastomoses demonstrated no differences in cross-sectional areas or compliance for the three suture techniques. This suggests that, unlike with end-to-end anastomoses, when constructing an end-to-side anastomosis in patients any of the three suture techniques may be acceptable.

  12. End-Use Efficiency to Lower Carbon Emissions

    International Nuclear Information System (INIS)

    Marnay, Chris; Osborn, Julie; Webber, Carrie

    2001-01-01

    Compelling evidence demonstrating the warming trend in global temperatures and the mechanism behind it, namely the anthropogenic emissions of carbon dioxide and other greenhouse gases (GHG), has spurred an international effort to reduce emissions of these gases. Despite improving efficiency of the U.S. economy in terms of energy cost per dollar of GDP since the signing of the Kyoto Protocol, energy consumption and carbon emissions are continuing to rise as the economy expands. This growing gap further emphasizes the importance of improving energy use efficiency as a component in the U.S. climate change mitigation program. The end-use efficiency research activities at Berkeley Lab incorporate residential, commercial, industrial, and transportation sectors. This paper focuses on two successful U.S. programs that address end-use efficiency in residential and commercial demand: energy efficient performance standards established by the Department of Energy (DOE) and the Environmental Protection Agency's (EPA's) ENERGY STAR(registered trademark) program

  13. Carotid Artery End-Diastolic Velocity and Future Cerebro-Cardiovascular Events in Asymptomatic High Risk Patients.

    Science.gov (United States)

    Chung, Hyemoon; Jung, Young Hak; Kim, Ki-Hyun; Kim, Jong-Youn; Min, Pil-Ki; Yoon, Young Won; Lee, Byoung Kwon; Hong, Bum-Kee; Rim, Se-Joong; Kwon, Hyuck Moon; Choi, Eui-Young

    2016-01-01

    Prognostic value of additional carotid Doppler evaluations to carotid intima-media thickness (IMT) and plaque has not been completely evaluated. A total of 1119 patients with risk factors for, but without, overt coronary artery disease (CAD), who underwent both carotid ultrasound and Doppler examination were included in the present study. Parameters of interest included peak systolic and end-diastolic velocities, resistive indices of the carotid arteries, IMT, and plaque measurements. The primary end-point was all-cause cerebro-cardiovascular events (CVEs) including acute myocardial infarction, coronary revascularization therapy, heart failure admission, stroke, and cardiovascular death. Model 1 covariates comprised age and sex; Model 2 also included hypertension, diabetes and smoking; Model 3 also had use of aspirin and statin; and Model 4 also included IMT and plaque. The mean follow-up duration was 1386±461 days and the mean age of the study population was 60±12 years. Amongst 1119 participants, 43% were women, 57% had a history of hypertension, and 23% had diabetes. During follow-up, 6.6% of patients experienced CVEs. Among carotid Doppler parameters, average common carotid artery end-diastolic velocity was the independent predictor for future CVEs after adjustments for all models variables (HR 0.95 per cm/s, 95% confident interval 0.91-0.99, p=0.034 in Model 4) and significantly increased the predictive value of Model 4 (global χ(2)=59.0 vs. 62.8, p=0.029). Carotid Doppler measurements in addition to IMT and plaque evaluation are independently associated with future CVEs in asymptomatic patients at risk for CAD.

  14. 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.)

  15. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States.

    Science.gov (United States)

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on (137)Cs and (210)Pb dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.

  16. Electrical conductance of carbon nanotubes with misaligned ends

    Energy Technology Data Exchange (ETDEWEB)

    Pantano, Antonio, E-mail: antonio.pantano@unipa.it; Muratore, Giuseppe; Montinaro, Nicola [Universita degli Studi di Palermo, Dipartimento di Ingegneria Chimica, Gestionale, Informatica e Meccanica (Italy)

    2013-09-15

    During a manufacturing process, when a straight carbon nanotube is placed on a substrate, e.g., production of transistors, its two ends are often misaligned. In this study, we investigate the effects of multiwall carbon nanotubes' (MWCNTs) outer diameter and chirality on the change in conductance due to misalignment of the two ends. The length of the studied MWCNTs was 120 nm, while the diameters ranged between 4 and 7 nm. A mixed finite element-tight-binding approach was carefully designed to realize reduction in computational time by orders of magnitude in calculating the deformation-induced changes in the electrical transport properties of the nanotubes. Numerical results suggest that armchair MWCNTs of small diameter should work better if used as conductors, while zigzag MWCNTs of large diameter are more suitable for building sensors.Graphical Abstract.

  17. Tidal and seasonal variation in particulate and dissolved organic carbon in the western dutch Wadden Sea and Marsdiep tidal inlet

    Science.gov (United States)

    Cadée, G. C.

    Seasonal variation in POC and DOC was measured in the Marsdiep tidal inlet of the Wadden Sea from March 1978 to June 1981, and compared with tidal variation. A POC peak was coincident with the phytoplankton peak (except for 1981), whereas a DOC peak occurred about one month later indicating autolysis and degradation of phytoplankton rather than excretion as the main source of this DOC. DOC production calculated from the spring increase amounted to 4.2 mg C·1 -1 or about 40% of the annual phytoplankton primary production in the area. This means that a large part of the phytoplankton production is not used directly by primary consumers but is converted into DOC. Tidal variation in DOC was correlated with salinity, pointing to a fresh water source for the bulk of it. POC was correlated with suspended matter content and phaeopigment, and slightly less with chlorophyll. Compared with the seasonal variation, tidal variation in chlorophyll and temperature was relatively small, but large in POC, DOC, suspended matter and salinity. Although import of POC and export of DOC through the Marsdiep inlet is large on an annual base, the transport cannot be measured directly because of the variability and precision limits of the measurements and as differences in content between ebb and flood current are only 15 and 5% of the POC and DOC content, respectively.

  18. Flow and wall shear stress in end-to-side and side-to-side anastomosis of venous coronary artery bypass grafts

    Directory of Open Access Journals (Sweden)

    Poulikakos Dimos

    2007-09-01

    Full Text Available Abstract Purpose Coronary artery bypass graft (CABG surgery represents the standard treatment of advanced coronary artery disease. Two major types of anastomosis exist to connect the graft to the coronary artery, i.e., by using an end-to-side or a side-to-side anastomosis. There is still controversy because of the differences in the patency rates of the two types of anastomosis. The purpose of this paper is to non-invasively quantify hemodynamic parameters, such as mass flow and wall shear stress (WSS, in end-to-side and side-to-side anastomoses of patients with CABG using computational fluid dynamics (CFD. Methods One patient with saphenous CABG and end-to-side anastomosis and one patient with saphenous CABG and side-to-side anastomosis underwent 16-detector row computed tomography (CT. Geometric models of coronary arteries and bypasses were reconstructed for CFD analysis. Blood flow was considered pulsatile, laminar, incompressible and Newtonian. Peri-anastomotic mass flow and WSS were quantified and flow patterns visualized. Results CFD analysis based on in-vivo CT coronary angiography data was feasible in both patients. For both types of CABG, flow patterns were characterized by a retrograde flow into the native coronary artery. WSS variations were found in both anastomoses types, with highest WSS values at the heel and lowest WSS values at the floor of the end-to-side anastomosis. In contrast, the highest WSS values of the side-to-side anastomosis configuration were found in stenotic vessel segments and not in the close vicinity of the anastomosis. Flow stagnation zones were found in end-to-side but not in side-to-side anastomosis, the latter also demonstrating a smoother stream division throughout the cardiac cycle. Conclusion CFD analysis of venous CABG based on in-vivo CT datasets in patients was feasible producing qualitative and quantitative information on mass flow and WSS. Differences were found between the two types of anastomosis

  19. Middle cerebral artery blood flow velocity during beach chair position for shoulder surgery under general anesthesia.

    Science.gov (United States)

    Hanouz, Jean-Luc; Fiant, Anne-Lise; Gérard, Jean-Louis

    2016-09-01

    The goal of the present study was to examine changes of middle cerebral artery (VMCA) blood flow velocity in patients scheduled for shoulder surgery in beach chair position. Prospective observational study. Operating room, shoulder surgery. Fifty-three consecutive patients scheduled for shoulder surgery in beach chair position. Transcranial Doppler performed after induction of general anesthesia (baseline), after beach chair positioning (BC1), during surgery 20minutes (BC2), and after back to supine position before stopping anesthesia (supine). Mean arterial pressure (MAP), end-tidal CO2, and volatile anesthetic concentration and VMCA were recorded at baseline, BC1, BC2, and supine. Postoperative neurologic complications were searched. Beach chair position induced decrease in MAP (baseline: 73±10mm Hg vs lower MAP recorded: 61±10mm Hg; P<.0001) requiring vasopressors and fluid challenge in 44 patients (83%). There was a significant decrease in VMCA after beach chair positioning (BC1: 33±10cm/s vs baseline: 39±14cm/s; P=.001). The VMCA at baseline (39±2cm/s), BC2 (35±14cm/s), and supine (39±14cm/s) were not different. The minimal alveolar concentration of volatile anesthetics, end-tidal CO2, SpO2, and MAP were not different at baseline, BC1, BC2, and supine. Beach chair position resulted in transient decrease in MAP requiring fluid challenge and vasopressors and a moderate decrease in VMCA. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Renal Artery Embolization - A First Line Treatment Option For End-Stage Hydronephrosis

    International Nuclear Information System (INIS)

    Mitra, Kakali; Prabhudesai, Vikramaditya; James, R. Lester; Jones, Robert W. A.; French, Michael E.; Cowling, Mark; West, David J.

    2004-01-01

    Conventionally poorly functioning hydronephrotic kidneys have been removed if they are symptomatic. In our unit, patients are offered renal artery embolization as an alternative treatment option. Patients and Methods: Fifteen patients (11 male, 4 female) with a mean age of 32.9 yr (20-51 yrs) have undergone renal artery embolization for symptomatic hydronephrosis with poor function. Mean follow-up was 64.13 weeks (range 14-200). All patients had loin pain and hydronephrosis. Twelve patients had primary pelvi-ureteric junction obstruction (PUJO). Two patients had poorly functioning hydronephrotic kidneys secondary to chronic calculous obstruction. One patient had chronic pain in an obstructed but reasonably functioning kidney following a previous pyeloplasty for PUJO which demanded intervention. Mean split function on renography was 11% (range 0-46%). Selective renal artery embolization was carried out under antibiotic cover using a 7 Fr balloon occlusion catheter and absolute alcohol, steel coils, and polyvinyl alcohol particles.Results: Nine patients developed post-embolization syndrome of self-limiting pain and pyrexia with no evidence of sepsis. One patient required readmission with this condition. One patient developed a hematoma at the puncture site. Mean hospital stay was 2.3 days. Fourteen patients are happy with the result and are completely pain free. One patient has minor discomfort but is delighted with the result. Nine patients have had follow-up ultrasound confirming resolution of the hydronephrosis. Conclusion: Renal artery embolization is an effective, safe, well-tolerated minimally invasive treatment option in end-stage hydronephrosis and we routinely offer it as an alternative to nephrectomy

  1. 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.

  2. 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

  3. End-Tidal CO2 Tension Is Predictive of Effective Nocturnal Oxygen Therapy in Patients with Chronic Heart Failure and Central Sleep Apnea.

    Science.gov (United States)

    Sugimura, Koichiro; Shinozaki, Tsuyoshi; Fukui, Shigefumi; Ogawa, Hiromasa; Shimokawa, Hiroaki

    2016-05-01

    Central sleep apnea (CSA) is characterized by recurring cycles of crescendo-decrescendo ventilation during sleep, and enhances sympathetic nerve activity. Thus CSA has a prognostic impact in patients with chronic heart failure (CHF). Although nocturnal oxygen (O2) therapy decreases frequency of CSA and improves functional exercise capacity, it is also known that some non-responders to the therapy exist. We thus aimed to identify predictors of responders to nocturnal O2 therapy in CHF patients with CSA. In 12 CHF patients with CSA hospitalized at our department, sleep study was performed at 2 consecutive nights. Patients nasally inhaled O2 at either the first or second night in a randomized manner. To predict the percentage reduction in apnea-hypopnea index (%ΔAHI) in response to the nocturnal O2 therapy, we performed multiple regression analysis with a stepwise method with variables including age, brain-natriuretic peptide, circulation time, baseline AHI, hypercapnic ventilatory response and end-tidal carbon dioxide tension (PETCO2). Nocturnal O2 therapy significantly decreased AHI (from 32 ± 13 /h to 12 ± 10 /h, P 50% reduction of AHI), with 88.9% of sensitivity and 66.7% of specificity. In conclusion, PETCO2 is useful to predict the efficacy of O2 therapy in CHF patients with CSA, providing important information to the current nocturnal O2 therapy.

  4. 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.

  5. Mechanisms of endothelial dysfunction in resistance arteries from patients with end-stage renal disease.

    Directory of Open Access Journals (Sweden)

    Leanid Luksha

    Full Text Available The study focuses on the mechanisms of endothelial dysfunction in the uremic milieu. Subcutaneous resistance arteries from 35 end-stage renal disease (ESRD patients and 28 matched controls were studied ex-vivo. Basal and receptor-dependent effects of endothelium-derived factors, expression of endothelial NO synthase (eNOS, prerequisites for myoendothelial gap junctions (MEGJ, and associations between endothelium-dependent responses and plasma levels of endothelial dysfunction markers were assessed. The contribution of endothelium-derived hyperpolarizing factor (EDHF to endothelium-dependent relaxation was impaired in uremic arteries after stimulation with bradykinin, but not acetylcholine, reflecting the agonist-specific differences. Diminished vasodilator influences of the endothelium on basal tone and enhanced plasma levels of asymmetrical dimethyl L-arginine (ADMA suggest impairment in NO-mediated regulation of uremic arteries. eNOS expression and contribution of MEGJs to EDHF type responses were unaltered. Plasma levels of ADMA were negatively associated with endothelium-dependent responses in uremic arteries. Preserved responses of smooth muscle to pinacidil and NO-donor indicate alterations within the endothelium and tolerance of vasodilator mechanisms to the uremic retention products at the level of smooth muscle. We conclude that both EDHF and NO pathways that control resistance artery tone are impaired in the uremic milieu. For the first time, we validate the alterations in EDHF type responses linked to kinin receptors in ESRD patients. The association between plasma ADMA concentrations and endothelial function in uremic resistance vasculature may have diagnostic and future therapeutic implications.

  6. Assessment of carbon monoxide values in smokers: a comparison of carbon monoxide in expired air and carboxyhaemoglobin in arterial blood

    DEFF Research Database (Denmark)

    Andersson, Mette F; Møller, Ann M

    2010-01-01

    Smoking increases perioperative complications. Carbon monoxide concentrations can estimate patients' smoking status and might be relevant in preoperative risk assessment. In smokers, we compared measurements of carbon monoxide in expired air (COexp) with measurements of carboxyhaemoglobin (COHb) ......) in arterial blood. The objectives were to determine the level of correlation and to determine whether the methods showed agreement and evaluate them as diagnostic tests in discriminating between heavy and light smokers....

  7. Dissolved organic carbon in the freshwater tidal reaches of the Schelde estuary

    DEFF Research Database (Denmark)

    Muylaert, K.; Dasseville, R.; De Brabandere, Loreto

    2005-01-01

    To unravel the factors that regulate DOC dynamics in the freshwater tidal reaches of the Schelde estuary, DOC concentration and biodegradability were monitored in the upper Schelde estuary and its major tributaries. Although the Schelde estuary possesses a densely populated and industrialized...... catchment, our data suggest that the bulk of DOC in the freshwater tidal reaches is not derived from waste water. This was concluded from the low biodegradability of DOC (on average 9%), DOC concentrations that are close to the mean for European rivers (4.61 mg/l) and the absence of an inverse relationship....../l), these blooms did not appear to produce large quantities of DOC in the freshwater tidal reaches as DOC concentrations were low when phytoplankton biomass was high. The fact that DOC concentrations were high in winter and decreased in summer suggests a predominantly terrestrial source of DOC in the freshwater...

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

    Science.gov (United States)

    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.

  9. 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

  10. Measurements of pulmonary gas exchange efficiency using expired gas and oximetry: results in normal subjects.

    Science.gov (United States)

    West, John B; Wang, Daniel L; Prisk, G Kim

    2018-04-01

    We are developing a novel, noninvasive method for measuring the efficiency of pulmonary gas exchange in patients with lung disease. The patient wears an oximeter, and we measure the partial pressures of oxygen and carbon dioxide in inspired and expired gas using miniature analyzers. The arterial Po 2 is then calculated from the oximeter reading and the oxygen dissociation curve, using the end-tidal Pco 2 to allow for the Bohr effect. This calculation is only accurate when the oxygen saturation is ideal alveolar Po 2 minus the measured arterial Po 2 . That measurement requires an arterial blood sample. The present study suggests that this noninvasive procedure will be valuable in assessing the degree of impaired gas exchange in patients with lung disease.

  11. The development and application practice of neglected tidal energy in China

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Li-qun; Liu, Chun-xia; Sun, Zhi-yi; Han, Ru-cheng [Department of Electronic and Information, Taiyuan University of Science and Technology, 030024 Taiyuan, Shanxi Province (China)

    2011-02-15

    Along the eastcoasts of China are large bodies of water, China has abundant ocean energy resource, such as the theory reserves of tidal resource is about 0.2 billion kW, as early as 1958, Jizhou tidal power station is the first tidal power station in China, which built in Shunde, Guangdong province, and more than 40 small tidal power stations are built in east coastal region in 1960s, and the total installed capacity is about 0.5 MW. But it is a pity, the application and development of tidal energy has not been regarded by the government and ordinary people due to the investment of power plant is big and the technology is not mature, so there are only several small tidal power stations in China, and Jiangxia tidal power station with an installed capacity of 3.2 MW is the most famous. Fortunately, with the rapid development of Chinese economic and society, the renewable and sustainable energy have been regarded by Chinese government, and the application and development of wind energy and solar energy is increasing in an incredible speed, and more and more specialists began to regard the application of tidal energy, and they thought that tidal energy can relieve the energy stress of east coastal region, and many layout of tidal energy exploitation is unfold in recently. This paper discusses the distribution zone and current developmental situation of tidal energy in China. Then, some application practice is described, such as tidal power station and tidal stream turbine. The policies and law of China central government and local governments are described in the following paragraph. At the end, the developmental prospect of tidal energy in future China and the development barriers and recommendations are introduced, respectively. (author)

  12. Effects of carbonated mineral water treatment in Băile Tuşnad on chronic arterial occlusive disease – a case report

    Directory of Open Access Journals (Sweden)

    Gabriela Dogaru

    2017-05-01

    Full Text Available Introduction. Băile Tușnad spa is recognized for its role in the prevention and rehabilitation treatment of cardiovascular diseases, including chronic arterial occlusive disease, due to the presence of natural therapeutic factors: carbonated mineral waters through their peripheral vasodilator effects, natural mofettes, stimulating bioclimate. Aim. The current study aimed to assess the clinical efficiency of natural therapeutic factors in Băile Tuşnad for the continuation of rehabilitation treatment in a patient with chronic arterial occlusive disease, in order to encourage walking, reduce cardiovascular risk and improve quality of life. Material and method. Patient N.M., aged 75, with multiple cardiovascular risk factors. In 2013, he was diagnosed with lower limb peripheral ischemia syndrome stage II B Fontaine, predominantly left claudication at about 100 m, for which balloon angioplasty was performed. He attended rehabilitation treatment for 3 years in Baile Tuşnad, consisting of carbonated mineral water baths for 15 minutes, aerotherapy for 30 minutes daily for the stimulation of walking, massotherapy, kinesiotherapy, performed daily for 16 days, and in 2016, at the Rehabilitation Hospital Cluj-Napoca. He was clinically evaluated before and at the end of treatment by the Visual Analogue Scale, the 10-m walking test, adverse reactions, Doppler ultrasound. Results. At the end of treatment, an increase in the walking distance and speed, a significant improvement in the quality of gait was found; claudication occurred after 250 m, pain in the lower limbs was improved. There were no side reactions. Conclusions. Rehabilitation treatment with natural therapeutic factors influenced the clinical and functional picture, determining a significant improvement in the quality of gait and quality of life.

  13. Time to tracheal extubation after coronary artery surgery with isoflurane, sevoflurane, or target-controlled propofol anesthesia: a prospective, randomized, controlled trial.

    Science.gov (United States)

    Parker, Francis C; Story, David A; Poustie, Stephanie; Liu, Guoming; McNicol, Larry

    2004-10-01

    To determine if anesthesia with sevoflurane or target-controlled propofol reduced the time to tracheal extubation after coronary artery bypass graft surgery compared with isoflurane anesthesia. A 3-arm (isoflurane, sevoflurane, or propofol), randomized, controlled trial with patients and intensive care staff blinded to the drug allocation. A single, tertiary referral hospital affiliated with the University of Melbourne. Three hundred sixty elective coronary artery surgery patients. Patients received either isoflurane (control group, 0.5%-2% end-tidal concentration), sevoflurane (1%-4% end-tidal concentration), or target-controlled infusion of propofol (1-8 microg/mL plasma target concentration) as part of a balanced, standardized anesthetic technique including 15 microg/kg of fentanyl. The primary outcome was time to tracheal extubation. The median time to tracheal extubation for the propofol group was 10.25 hours (interquartile range [IQR] 8.08-12.75), the sevoflurane group 9.17 hours (IQR 6.25-11.25), and the isoflurane group 7.67 hours (IQR 6.25-9.42). Intraoperatively, the propofol group required less vasopressor (p = 0.002) and more vasodilator therapy (nitroglycerin p = 0.01, nitroprusside p = 0.002). There was no difference among the groups in time to intensive care unit discharge. The median time to tracheal extubation was significantly longer for the target-controlled propofol group. A significantly greater number in this group required the use of a vasodilator to control intraoperative hypertension.

  14. Intra-arterial digital subtraction angiography (IA-DSA) with carbon dioxide

    International Nuclear Information System (INIS)

    Takeda, Toshiaki; Ido, Kunio; Yuasa, Yuji

    1988-01-01

    Intra-Arterial Digital Subtraction Angiography (IA-DSA) with Carbon Dioxide (CO 2 ) was performed on 41 patients mainly with liver or renal diseases, and its angiographic manifestation was compared with that of conventional angiography. Although the image quality of the arterial or capillary phase was inferior to that of conventional angiography with iodinated contrast media, the detectablity of arterio-venous shunting was excellent. In fact, DSA with CO 2 revealed the presence of A-V (A-P) shunt in 26 patients (26/41:63.4 % HCC, 13/15:86.7% metastatic liver tumor, 2/3:66.7 % RCC, 1/5:20 %). On the other hand, conventional angiography was able to show in only 5 cases. DSA with CO 2 will become an effective method for detecting minute arterio-venous shunting which can not be demonstrated with conventional angiography. (author)

  15. 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

  16. Carbon dioxide hepatic arterial DSA and CT angiography in swine model

    International Nuclear Information System (INIS)

    Tan Huaqiao; Hu Hongjie; Huang Wenxin; Zhang Shizheng; Dong Yonghua; Zhou Dachun

    2005-01-01

    Objective: To evaluate the imaging findings of carbon dioxide hepatic arterial DSA and CT angiography in normal swine. Methods: In general anaesthesia, hepatic arterial DSA was performed with 10 ml iodinated contrast medium (5 ml/s, 10 ml) in 5 normal swine, and then repeated hepatic arterial CO 2 -DSA was performed with a total of 30-50 ml CO 2 injected by manually operated syringe at the velocity of 5-8 ml/s, followed by CO 2 -CT angiography. All the swine were sacrificed after the procedure, the selective hepatic segments were removed, and pathological examination was carried out. The radiological features of hepatic arterial DSA with iodinated contrast medium and CO 2 and CT angiography with CO 2 were analyzed. The ability of showing the arterio-venous shunt was compared. Results: Hepatic arterio-portal shunt was found in the advanced arterial phase of CO 2 -DSA in three of five swine, which was furthermore demonstrated by CO 2 -CT angiography, but iodinated contrast medium DSA showed no arterio-portal shunt in all swine. The gaseous CO 2 in portal vein was absorbed within 1-3 minutes. No CO 2 shunted into the hepatic vein during CO 2 -DSA and CO 2 -CTA. Histology didn't reveal any abnormal changes caused by CO 2 shunt in the swine liver. Conclusion: (1) Hepatic arterial CO 2 -DSA and CO 2 -CTA can reveal arterio-portal shunt that isn't seen with iodinated contrast medium, the gaseous CO 2 in portal vein was absorbed within 1-3 minutes. (2) The gaseous CO 2 can't shunt into hepatic vein when the hepatic artery is perfused with CO 2 in normal swine. (authors)

  17. Tidally driven export of dissolved organic carbon, total mercury, and methylmercury from a mangrove-dominated estuary

    Science.gov (United States)

    Bergamaschi, B.A.; Krabbenhoft, D.P.; Aiken, G.R.; Patino, E.; Rumbold, D.G.; Orem, W.H.

    2012-01-01

    The flux of dissolved organic carbon (DOC) from mangrove swamps accounts for 10% of the global terrestrial flux of DOC to coastal oceans. Recent findings of high concentrations of mercury (Hg) and methylmercury (MeHg) in mangroves, in conjunction with the common co-occurrence of DOC and Hg species, have raised concerns that mercury fluxes may also be large. We used a novel approach to estimate export of DOC, Hg, and MeHg to coastal waters from a mangrove-dominated estuary in Everglades National Park (Florida, USA). Using in situ measurements of fluorescent dissolved organic matter as a proxy for DOC, filtered total Hg, and filtered MeHg, we estimated the DOC yield to be 180 (??12.6) g C m -2 yr -1, which is in the range of previously reported values. Although Hg and MeHg yields from tidal mangrove swamps have not been previously measured, our estimated yields of Hg species (28 ?? 4.5 ??g total Hg m -2 yr -1 and 3.1 ?? 0.4 ??g methyl Hg m -2 yr -1) were five times greater than is typically reported for terrestrial wetlands. These results indicate that in addition to the well documented contributions of DOC, tidally driven export from mangroves represents a significant potential source of Hg and MeHg to nearby coastal waters. ?? 2011 American Chemical Society.

  18. Use of end-to-side arterial and venous anastomosis techniques for renal transplantation in two dogs.

    Science.gov (United States)

    Phillips, Heidi; Aronson, Lillian R

    2012-02-01

    A sexually intact male Old English Sheepdog and a sexually intact female Bull Terrier were evaluated for renal dysplasia and chronic renal failure, respectively. Both dogs were anemic and had high serum concentrations of urea nitrogen and creatinine. Electrolyte abnormalities (calcium and phosphorus) were also evident. The decision was made to pursue renal transplantation, and donor dogs were identified. End-to-side anastomosis of the renal artery and vein of each donor's left kidney to the recipient's ipsilateral external iliac artery and vein, respectively, was performed. The left caudal abdominal musculature was scarified by making an incision, and nephropexy to that musculature was performed with a simple interrupted pattern of polypropylene sutures. No intraoperative or postoperative complications associated with the vascular anastomoses were encountered. Azotemia, anemia, and electrolyte imbalances resolved after transplantation. The end-to-side anastomosis technique described here, which is a preferred method in human medicine, was successful, providing an alternative to other renal transplantation techniques in dogs. Additional studies are needed to determine whether any vascular anastomosis technique is preferable for use in dogs requiring renal transplantation.

  19. 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

  20. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans.

    Directory of Open Access Journals (Sweden)

    Andrzej F Frydrychowski

    Full Text Available PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1 pial artery pulsation (cc-TQ; (2 cerebral blood flow velocity (CBFV; (3 peripheral blood pressure; and (4 possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS, CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2 was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT and swayed to the back (initial position. RESULTS: In the first group (n = 10 during BOPT, sas-TQ and pulse pressure (PP decreased (-17.6% and -17.9%, respectively and CBFV increased (+35.0%, while cc-TQ did not change (+1.91%. In the second group, in the initial position (n = 22 cc-TQ and CBFV increased (106.6% and 20.1%, respectively, while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively. End-tidal CO(2 remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74. CONCLUSIONS: Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral

  1. 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.

  2. Atmospheric Carbon Injection Linked to End-Triassic Mass Extinction

    NARCIS (Netherlands)

    Ruhl, M.; Bonis, N.R.; Reichart, G.J.; Sinninghe Damsté, J.S.; Kürschner, W.M.

    2011-01-01

    The end-Triassic mass extinction (similar to 201.4 million years ago), marked by terrestrial ecosystem turnover and up to similar to 50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope

  3. 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.

  4. Effects of carbon dioxide insufflation on regional cerebral oxygenation during laparoscopic surgery in children: a prospective study.

    Science.gov (United States)

    Tuna, Ayca Tas; Akkoyun, Ibrahim; Darcin, Sevtap; Palabiyik, Onur

    2016-01-01

    Laparoscopic surgery has become a popular surgical tool when compared to traditional open surgery. There are limited data on pediatric patients regarding whether pneumoperitoneum affects cerebral oxygenation although end-tidal CO2 concentration remains normal. Therefore, this study was designed to evaluate the changes of cerebral oxygen saturation using near-infrared spectroscope during laparoscopic surgery in children. The study comprised forty children who were scheduled for laparoscopic (Group L, n=20) or open (Group O, n=20) appendectomy. Hemodynamic variables, right and left regional cerebral oxygen saturation (RrSO2 and LrSO2), fraction of inspired oxygen, end-tidal carbon dioxide pressure (PETCO2), peak inspiratory pressure (Ppeak), respiratory minute volume, inspiratory and end-tidal concentrations of sevoflurane and body temperature were recorded. All parameters were recorded after anesthesia induction and before start of surgery (T0, baseline), 15min after start of surgery (T1), 30min after start of surgery (T2), 45min after start of surgery (T3), 60min after start of surgery (T4) and end of the surgery (T5). There were progressive decreases in both RrSO2 and LrSO2 levels in both groups, which were not statistically significant at T1, T2, T3, T4. The RrSO2 levels of Group L at T5 were significantly lower than that of Group O. One patient in Group L had an rSO2 value <80% of the baseline value. Carbon dioxide insufflation during pneumoperitoneum in pediatric patients may not affect cerebral oxygenation under laparoscopic surgery. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  5. [Effects of carbon dioxide insufflation on regional cerebral oxygenation during laparoscopic surgery in children: a prospective study].

    Science.gov (United States)

    Tuna, Ayca Tas; Akkoyun, Ibrahim; Darcin, Sevtap; Palabiyik, Onur

    2016-01-01

    Laparoscopic surgery has become a popular surgical tool when compared to traditional open surgery. There are limited data on pediatric patients regarding whether pneumoperitoneum affects cerebral oxygenation although end-tidal CO2 concentration remains normal. Therefore, this study was designed to evaluate the changes of cerebral oxygen saturation using near-infrared spectroscope during laparoscopic surgery in children. The study comprised forty children who were scheduled for laparoscopic (Group L, n=20) or open (Group O, n=20) appendectomy. Hemodynamic variables, right and left regional cerebral oxygen saturation (RrSO2 and LrSO2), fraction of inspired oxygen, end-tidal carbon dioxide pressure (PETCO2), peak inspiratory pressure (Ppeak), respiratory minute volume, inspiratory and end-tidal concentrations of sevoflurane and body temperature were recorded. All parameters were recorded after anesthesia induction and before start of surgery (T0, baseline), 15min after start of surgery (T1), 30min after start of surgery (T2), 45min after start of surgery (T3), 60min after start of surgery (T4) and end of the surgery (T5). There were progressive decreases in both RrSO2 and LrSO2 levels in both groups, which were not statistically significant at T1, T2, T3, T4. The RrSO2 levels of Group L at T5 were significantly lower than that of Group O. One patient in Group L had an rSO2 value <80% of the baseline value. Carbon dioxide insufflation during pneumoperitoneum in pediatric patients may not affect cerebral oxygenation under laparoscopic surgery. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  6. The carbonate-silicate cycle and CO2/climate feedbacks on tidally locked terrestrial planets.

    Science.gov (United States)

    Edson, Adam R; Kasting, James F; Pollard, David; Lee, Sukyoung; Bannon, Peter R

    2012-06-01

    Atmospheric gaseous constituents play an important role in determining the surface temperatures and habitability of a planet. Using a global climate model and a parameterization of the carbonate-silicate cycle, we explored the effect of the location of the substellar point on the atmospheric CO(2) concentration and temperatures of a tidally locked terrestrial planet, using the present Earth continental distribution as an example. We found that the substellar point's location relative to the continents is an important factor in determining weathering and the equilibrium atmospheric CO(2) level. Placing the substellar point over the Atlantic Ocean results in an atmospheric CO(2) concentration of 7 ppmv and a global mean surface air temperature of 247 K, making ∼30% of the planet's surface habitable, whereas placing it over the Pacific Ocean results in a CO(2) concentration of 60,311 ppmv and a global temperature of 282 K, making ∼55% of the surface habitable.

  7. Tidal Love numbers of neutron and self-bound quark stars

    International Nuclear Information System (INIS)

    Postnikov, Sergey; Prakash, Madappa; Lattimer, James M.

    2010-01-01

    Gravitational waves from the final stages of inspiraling binary neutron stars are expected to be one of the most important sources for ground-based gravitational wave detectors. The masses of the components are determinable from the orbital and chirp frequencies during the early part of the evolution, and large finite-size (tidal) effects are measurable toward the end of inspiral, but the gravitational wave signal is expected to be very complex at this time. Tidal effects during the early part of the evolution will form a very small correction, but during this phase the signal is relatively clean. The accumulated phase shift due to tidal corrections is characterized by a single quantity related to a star's tidal Love number. The Love number is sensitive, in particular, to the compactness parameter M/R and the star's internal structure, and its determination could provide an important constraint to the neutron star radius. We show that Love numbers of self-bound strange quark matter stars are qualitatively different from those of normal neutron stars. Observations of the tidal signature from coalescing compact binaries could therefore provide an important, and possibly unique, way to distinguish self-bound strange quark stars from normal neutron stars. Tidal signatures from self-bound strange quark stars with masses smaller than 1M · are substantially smaller than those of normal stars owing to their smaller radii. Thus tidal signatures of stars less massive than 1M · are probably not detectable with Advanced LIGO. For stars with masses in the range 1-2M · , the anticipated efficiency of the proposed Einstein telescope would be required for the detection of tidal signatures.

  8. Endotoxemia reduces cerebral perfusion but enhances dynamic cerebrovascular autoregulation at reduced arterial carbon dioxide tension*

    DEFF Research Database (Denmark)

    Brassard, Patrice; Kim, Yu-Sok; van Lieshout, Johannes

    2012-01-01

    OBJECTIVE:: The administration of endotoxin to healthy humans reduces cerebral blood flow but its influence on dynamic cerebral autoregulation remains unknown. We considered that a reduction in arterial carbon dioxide tension would attenuate cerebral perfusion and improve dynamic cerebral autoreg...

  9. Tidal impact on the dynamic behavior of dissolved pharmaceuticals in the Yangtze Estuary, China.

    Science.gov (United States)

    Zhao, Heng; Zhou, Jun Liang; Zhang, Jing

    2015-12-01

    The dynamic behavior of 24 dissolved pharmaceuticals over tidal cycles in the Yangtze Estuary, China was studied to assess the tidal impact on the fate of pharmaceutical residues. The results show that most pharmaceuticals were frequently detected with concentrations from below detection to 27.2 ng/L, with sulfamethoxazole, sulfamethazine, erythromycin, thiamphenicol and florfenicol dominating. During tidal cycles, pharmaceutical concentrations decreased during tidal rise, then increasing during tidal receding for all locations, except at site S2 which showed an opposite trend due to unique water movement there. It was observed that most compounds showed a non-conservative behavior, while diazepam and sulfamethoxazole displayed a conservative behavior. The pharmaceutical concentrations were found to increase with dissolved organic carbon (DOC) concentration, suggesting DOC as a carrier of pharmaceuticals. In addition, many compounds showed a significant negative relationship with suspended particulate matter (SPM) concentration, indicating SPM-water interactions as a control of pharmaceutical behavior in estuarine environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. A one-dimensional biomorphodynamic model of tidal flats: Sediment sorting, marsh distribution, and carbon accumulation under sea level rise

    Science.gov (United States)

    Zhou, Zeng; Ye, Qinghua; Coco, Giovanni

    2016-07-01

    We develop a biomorphodynamic model to investigate sediment and vegetation dynamics on a schematic intertidal flat characterized by an initially well-mixed sand-mud mixture. Major interactions between tides, wind waves, salt marshes, sediment transport and sea level rise (SLR) are taken into account. For a bare flat under only tidal action, the model predicts a convex cross-shore profile with the surficial distribution of mud and sand on the upper and lower part of the intertidal flat, respectively. When wind waves are strong, the intertidal flat is highly eroded resulting in a concave profile near the high water mark. This behavior is pronouncedly altered when the intertidal flat is vegetated with the presence of salt marshes. Numerical results suggest that a considerable amount of mud can still remain in the vegetated region even when wave action is strong. A steeper transition zone forms at the boundary between salt marshes and bare flats because of the differential sediment deposition in the two neighboring regions. The inclusion of wind waves is found to considerably enhance the size of the marsh-edge transition zone. For the numerical experiments designed in this study, the profile shape and sediment sorting behavior of tidal flats are not significantly modified by a gradual rising sea level. However, the impacts of SLR on vegetated tidal flats are still manifold: (a) driving the landward migration of intertidal zone and salt marshes; (b) enhancing sediment erosion on intertidal flats; and (c) drowning salt marshes under limited sediment supply with the constrain of seawalls. Finally, model results suggest that organic carbon accumulation on marshlands may be enhanced with an increasing SLR rate provided that salt marshes are not drowned.

  11. 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)

  12. Physiologic Evaluation of Ventilation Perfusion Mismatch and Respiratory Mechanics at Different Positive End-expiratory Pressure in Patients Undergoing Protective One-lung Ventilation.

    Science.gov (United States)

    Spadaro, Savino; Grasso, Salvatore; Karbing, Dan Stieper; Fogagnolo, Alberto; Contoli, Marco; Bollini, Giacomo; Ragazzi, Riccardo; Cinnella, Gilda; Verri, Marco; Cavallesco, Narciso Giorgio; Rees, Stephen Edward; Volta, Carlo Alberto

    2018-03-01

    Arterial oxygenation is often impaired during one-lung ventilation, due to both pulmonary shunt and atelectasis. The use of low tidal volume (VT) (5 ml/kg predicted body weight) in the context of a lung-protective approach exacerbates atelectasis. This study sought to determine the combined physiologic effects of positive end-expiratory pressure and low VT during one-lung ventilation. Data from 41 patients studied during general anesthesia for thoracic surgery were collected and analyzed. Shunt fraction, high V/Q and respiratory mechanics were measured at positive end-expiratory pressure 0 cm H2O during bilateral lung ventilation and one-lung ventilation and, subsequently, during one-lung ventilation at 5 or 10 cm H2O of positive end-expiratory pressure. Shunt fraction and high V/Q were measured using variation of inspired oxygen fraction and measurement of respiratory gas concentration and arterial blood gas. The level of positive end-expiratory pressure was applied in random order and maintained for 15 min before measurements. During one-lung ventilation, increasing positive end-expiratory pressure from 0 cm H2O to 5 cm H2O and 10 cm H2O resulted in a shunt fraction decrease of 5% (0 to 11) and 11% (5 to 16), respectively (P ventilation, high positive end-expiratory pressure levels improve pulmonary function without increasing high V/Q and reduce driving pressure.

  13. Establishing experimental model of human internal carotid artery siphon segment in canine common carotid artery

    International Nuclear Information System (INIS)

    Cui Xuee; Li Minghua; Wang Yongli; Cheng Yingsheng; Li Wenbin

    2005-01-01

    Objective: To study the feasibility of establishing experimental model of human internal carotid artery siphon segment in canine common carotid artery (CCA) by end-to-end anastomoses of one side common carotid artery segment with the other side common carotid artery. Methods: Surgical techniques were used to make siphon model in 8 canines. One side CCA was taken as the parent artery and anastomosing with the cut off contra-lateral CCA segment which has passed through within the S-shaped glass tube. Two weeks after the creation of models angiography showed the model siphons were patent. Results: Experimental models of human internal carotid artery siphon segment were successfully made in all 8 dogs. Conclusions: It is practically feasible to establish experimental canine common carotid artery models of siphon segment simulating human internal carotid artery. (authors)

  14. Rest period duration of the coronary arteries: Implications for magnetic resonance coronary angiography

    International Nuclear Information System (INIS)

    Shechter, Guy; Resar, Jon R.; McVeigh, Elliot R.

    2005-01-01

    Magnetic resonance (MR) and computed tomography coronary imaging is susceptible to artifacts caused by motion of the heart. The presence of rest periods during the cardiac and respiratory cycles suggests that images free of motion artifacts could be acquired. In this paper, we studied the rest period (RP) duration of the coronary arteries during a cardiac contraction and a tidal respiratory cycle. We also studied whether three MR motion correction methods could be used to increase the respiratory RP duration. Free breathing x-ray coronary angiograms were acquired in ten patients. The three-dimensional (3D) structure of the coronary arteries was reconstructed from a biplane acquisition using stereo reconstruction methods. The 3D motion of the arterial model was then recovered using an automatic motion tracking algorithm. The motion field was then decomposed into separate cardiac and respiratory components using a cardiac respiratory parametric model. For the proximal-to-middle segments of the right coronary artery (RCA), a cardiac RP (<1 mm 3D displacement) of 76±34 ms was measured at end systole (ES), and 65±42 ms in mid-diastole (MD). The cardiac RP was 80±25 ms at ES and 112±42 ms at MD for the proximal 5 cm of the left coronary tree. At end expiration, the respiratory RP (in percent of the respiratory period) was 26±8% for the RCA and 27±17% for the left coronary tree. Left coronary respiratory RP (<0.5 mm 3D displacement) increased with translation (32% of the respiratory period), rigid body (51%), and affine (79%) motion correction. The RCA respiratory RP using translational (27%) and rigid body (33%) motion correction were not statistically different from each other. Measurements of the cardiac and respiratory rest periods will improve our understanding of the temporal and spatial resolution constraints for coronary imaging

  15. Development of end-selective functionalized carbon nanotubes for biomedical applications

    Science.gov (United States)

    Lee, Seung Ho; Kim, Wan Sun; Lee, Ha Rim; Park, Kyu Chang; Lee, Chang Hoon; Park, Hun Kuk; Kim, Kyung Sook

    2015-12-01

    Carbon nanotube (CNT) is a type of carbon allotrope with excellent physical and electrical properties, including high thermal conductivity, mechanical strength, and thermal stability. Therefore, applications of CNT have been considered for a variety of fields, including biosensors, molecular electronics, X-ray, and fuel cells. However, the application of CNT to biomedicine is limited because this material is cytotoxic and inhomogeneous. In particular, the irregularity in the structural properties of paste or bundle-type CNTs causes an uncontrolled modification in biomolecules. Therefore, using CNT as biosensors to obtain quantitative analyses is difficult. In this study, we developed a new method to perform end-selective functionalization of CNT in order to enable quantitative analysis for biomedical applications. The process was as follows: (1) etching the tip of vertically-aligned CNTs under optimum conditions, (2) oxidation of exposed CNTs, and (3) end-selective linkage of functionalized CNTs with biomolecules (dsDNA).

  16. Lambda-guided calculation method (LGC method) for xenon/CT CBF

    Energy Technology Data Exchange (ETDEWEB)

    Sase, Shigeru [Anzai Medical Co., Ltd., Tokyo (Japan); Honda, Mitsuru; Kushida, Tsuyoshi; Seiki, Yoshikatsu; Machida, Keiichi; Shibata, Iekado [Toho Univ., Tokyo (Japan). School of Medicine

    2001-12-01

    A quantitative CBF calculation method for xenon/CT was developed by logically estimating time-course change rate (rate constant) of arterial xenon concentration from that of end-tidal xenon concentration. A single factor ({gamma}) was introduced to correlate the end-tidal rate constant (Ke) with the arterial rate constant (Ka) in a simplified equation. This factor ({gamma}) is thought to reflect the diffusing capacity of the lung for xenon. When an appropriate value is given to {gamma}, it is possible to calculate the arterial rate constant (Calculated Ka) from Ke. To determine {gamma} for each xenon/CT CBF examination, a procedure was established which utilizes the characteristics of white matter lambda; lambda refers to xenon brain-blood partition coefficient. Xenon/CT studies were performed on four healthy volunteers. Hemispheric CBF values (47.0{+-}9.0 ml/100 g/min) with use of Calculated Ka were close to the reported normative values. For a 27-year-old healthy man, the rate constant for the common carotid artery was successfully measured and nearly equal to Calculated Ka. The authors conclude the method proposed in this work, lambda-guided calculation method, could make xenon/CT CBF substantially reliable and quantitative by effective use of end-tidal xenon. (author)

  17. Lambda-guided calculation method (LGC method) for xenon/CT CBF

    International Nuclear Information System (INIS)

    Sase, Shigeru; Honda, Mitsuru; Kushida, Tsuyoshi; Seiki, Yoshikatsu; Machida, Keiichi; Shibata, Iekado

    2001-01-01

    A quantitative CBF calculation method for xenon/CT was developed by logically estimating time-course change rate (rate constant) of arterial xenon concentration from that of end-tidal xenon concentration. A single factor (γ) was introduced to correlate the end-tidal rate constant (Ke) with the arterial rate constant (Ka) in a simplified equation. This factor (γ) is thought to reflect the diffusing capacity of the lung for xenon. When an appropriate value is given to γ, it is possible to calculate the arterial rate constant (Calculated Ka) from Ke. To determine γ for each xenon/CT CBF examination, a procedure was established which utilizes the characteristics of white matter lambda; lambda refers to xenon brain-blood partition coefficient. Xenon/CT studies were performed on four healthy volunteers. Hemispheric CBF values (47.0±9.0 ml/100 g/min) with use of Calculated Ka were close to the reported normative values. For a 27-year-old healthy man, the rate constant for the common carotid artery was successfully measured and nearly equal to Calculated Ka. The authors conclude the method proposed in this work, lambda-guided calculation method, could make xenon/CT CBF substantially reliable and quantitative by effective use of end-tidal xenon. (author)

  18. 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.

  19. 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.

  20. 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.

  1. The Carbon Budget of Coastal Waters of Eastern North America

    Science.gov (United States)

    Najjar, R.; Boyer, E. W.; Burdige, D.; Butman, D. E.; Cai, W. J.; Canuel, E. A.; Chen, R. F.; Friedrichs, M. A.; Griffith, P. C.; Herrmann, M.; Kemp, W. M.; Kroeger, K. D.; Mannino, A.; McCallister, S. L.; McGillis, W. R.; Mulholland, M. R.; Salisbury, J.; Signorini, S. R.; Tian, H.; Tzortziou, M.; Vlahos, P.; Wang, A. Z.; Zimmerman, R. C.; Pilskaln, C. H.

    2015-12-01

    Observations and the output of numerical and statistical models are synthesized to construct a carbon budget of the coastal waters of eastern North America. The domain extends from the head of tide to (roughly) the continental shelf break and from southern Florida to southern Nova Scotia. The domain area is 2% tidal wetlands, 19% estuarine open water, and 78% shelf water. Separate budgets are constructed for inorganic and organic carbon; for tidal wetlands, estuaries, and shelf waters; and for three main subregions: the Gulf of Maine, the Mid-Atlantic Bight, and the South Atlantic Bight. Net primary production for the study region is about 150 Tg C yr-1, with 12% occurring in tidal wetlands and 7% in estuaries. Though respiration and photosynthesis are nearly balanced in most systems and regions, tidal wetlands and shelf waters are each found to be net autotrophic whereas estuaries are net heterotrophic. The domain as a whole is a sink of 5 Tg C yr-1 of atmospheric CO2, with tidal wetlands and shelf waters taking up 10 Tg C yr-1 (split roughly equally) and estuaries releasing 5 Tg C yr-1 to the atmosphere. Carbon burial is about 3 Tg C yr-1, split roughly equally among tidal wetlands, estuaries, and shelf waters. Rivers supply 6-7 Tg C yr-1 to estuaries, about 2/3 of which is organic. Tidal wetlands supply an additional 4 Tg C yr-1 to estuaries, about half of which is organic. Carbon in organic and inorganic forms is exported from estuaries to shelf waters and from shelf waters to the open ocean. In summary, tidal wetlands and estuaries, though small in area, contribute substantially to the overall carbon budget of the region.

  2. Stick-slip Cycles and Tidal Modulation of Ice Stream Flow

    Science.gov (United States)

    Lipovsky, B.; Dunham, E. M.

    2016-12-01

    The reactivation of a single dormant Antarctic ice stream would double the continent's mass imbalance. Despite importance of understanding the likelihood of such an event, direct observation of the basal processes that lead to the activation and stagnation of streaming ice are minimal. As the only ice stream undergoing stagnation, the Whillans Ice Plain (WIP) occupies a central role in our understanding of these subglacial processes. Complicating matters is the observation, from GPS records, that the WIP experiences most of its motion during episodes of rapid sliding. These sliding events are tidally modulated and separated by 12 hour periods of quiescence. We conduct numerical simulations of ice stream stick-slip cycles. Our simulations include rate- and state-dependent frictional sliding, tidal forcing, inertia, upstream loading in a cross-stream, thickness-averaged formulation. Our principal finding is that ice stream motion may respond to ocean tidal forcing with one of two end member behaviors. In one limit, tidally modulated slip events have rupture velocities that approach the shear wave speed and slip events have a duration that scales with the ice stream width divided by the shear wave speed. In the other limit, tidal modulation results in ice stream sliding velocities with lower amplitude variation but at much longer timescales, i.e. semi-diurnal and longer. This latter behavior more closely mimics the behavior of several active ice streams (Bindschadler, Rutford). We find that WIP slip events exist between these two end member behaviors: rupture velocities are far below the inertial limit yet sliding occurs only episodically. The continuum of sliding behaviors is governed by a critical ice stream width over which slip event nucleate. When the critical width is much longer than the ice stream width, slip events are unable to nucleate. The critical width depends on the subglacial effective pressure, ice thickness, and frictional and elastic constitutive

  3. Carbon dioxide narcosis due to inappropriate oxygen delivery: a case report.

    Science.gov (United States)

    Herren, Thomas; Achermann, Eva; Hegi, Thomas; Reber, Adrian; Stäubli, Max

    2017-07-28

    Oxygen delivery to patients with chronic obstructive pulmonary disease may be challenging because of their potential hypoxic ventilatory drive. However, some oxygen delivery systems such as non-rebreathing face masks with an oxygen reservoir bag require high oxygen flow for adequate oxygenation and to avoid carbon dioxide rebreathing. A 72-year-old Caucasian man with severe chronic obstructive pulmonary disease was admitted to the emergency department because of worsening dyspnea and an oxygen saturation of 81% measured by pulse oximetry. Oxygen was administered using a non-rebreathing mask with an oxygen reservoir bag attached. For fear of removing the hypoxic stimulus to respiration the oxygen flow was inappropriately limited to 4L/minute. The patient developed carbon dioxide narcosis and had to be intubated and mechanically ventilated. Non-rebreathing masks with oxygen reservoir bags must be fed with an oxygen flow exceeding the patient's minute ventilation (>6-10 L/minute.). If not, the amount of oxygen delivered will be too small to effectively increase the arterial oxygen saturation. Moreover, the risk of carbon dioxide rebreathing dramatically increases if the flow of oxygen to a non-rebreathing mask is lower than the minute ventilation, especially in patients with chronic obstructive pulmonary disease and low tidal volumes. Non-rebreathing masks (with oxygen reservoir bags) must be used cautiously by experienced medical staff and with an appropriately high oxygen flow of 10-15 L/minute. Nevertheless, arterial blood gases must be analyzed regularly for early detection of a rise in partial pressure of carbon dioxide in arterial blood in patients with chronic obstructive pulmonary disease and a hypoxic ventilatory drive. These patients are more safely managed using a nasal cannula with an oxygen flow of 1-2L/minute or a simple face mask with an oxygen flow of 5L/minute.

  4. Dynamics and fate of SOC in tidal marshes along a salinity gradient (Scheldt estuary, Belgium)

    Science.gov (United States)

    Van de Broek, Marijn; Temmermann, Stijn; Merckx, Roel; Wang, Zhengang; Govers, Gerard

    2016-04-01

    Coastal ecosystems have been attributed the potential to store large amounts of organic carbon (OC), often referred to as blue carbon, of which a considerable amount is stored in tidal marsh soils. Large uncertainties still exist with respect to the amount and controlling factors of soil organic carbon (SOC) stored in these ecosystems. Moreover, most research has focused on SOC dynamics of saltmarshes, while brackish and freshwater marshes are often even more productive and thus receive even larger organic carbon inputs. Therefore, in this study the OC dynamics of tidal marsh soils along an estuarine gradient are studied in order to contribute to our knowledge of 1) the stocks, 2) the controlling factors and 3) the fate of SOC in tidal marshes with different environmental characteristics. This research thus contributes to a better understanding of the potential of coastal environments to store organic carbon under future climatic changes. Soil and vegetation samples are collected in tidal salt-, brackish- and freshwater marshes in the Scheldt estuary (Belgium - The Netherlands). At each tidal marsh, three replicate soil cores up to 1.5m depth in 0.03m increments are collected at locations with both a low and a high elevation. These cores are analyzed for OC, stable C and N isotopes, bulk density and texture. Incubation experiments of topsoil samples were conducted and both aboveground and belowground biomass were collected. The results show that SOC stocks (range: 13,5 - 35,4 kg OC m-2), standing biomass (range: 2000 - 7930 g DW m-2) and potential soil respiration of CO2 (range: 0,03 - 0,12 % per unit OC per day) decrease with increasing salinity. This shows that both the amount of OC from local macrophytes and the quality of the organic matter are important factors controlling the SOC stocks. In addition, based on the analysis of stable C and N isotopes, it appears that when a significant fraction of SOC is derived from local macrophytes, higher SOC stocks are

  5. 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

  6. 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.

  7. Evaluation of anastomosis between intrahepatic or extrahepatic vessels by intra-arterial digital subtraction angiography using carbon dioxide

    International Nuclear Information System (INIS)

    Miyazono, Nobuaki; Inoue, Hiroki; Ueno, Kazuto; Nishida, Hirotoshi; Kanetsuki, Ichirou; Miyake, Satoshi; Nakajo, Masayuki

    1995-01-01

    Carbon dioxide (CO 2 ) intra-arterial subtraction angiography (IADSA) was performed in 31 patients with various hepatobiliary disease. The injection sites of CO 2 were proper hepatic artery (10/31; group A), segmental hepatic artery (18/31; group B), and peripheral inferior phrenic artery (3/31; group C), respectively. In group A, only the third order branches of the portal venous system were visualized anterogradely in 8 of 10 patients. In group B, the microcatheter was placed coaxially through a 5 French guiding catheter at the main arterial supply of the tumor in 7 patients and at the peripheral segmental branch of the hepatic artery in 11 patients. The portal venous system was visualized retrogradely in all of the patients regardless of the injection site. The injected CO 2 may flow back into the portal vein through the anastmosis known as the peribiliary or periportal plexus. In group C, not only the portal vein but also the pulmonary artery or pericardial vein were visualized by this method. CO 2 -IADSA was useful to image the minute communications between the various vessels, which have been not hitherto visualized by iodinated contrast medium. (author)

  8. Evaluation of anastomosis between intrahepatic or extrahepatic vessels by intra-arterial digital subtraction angiography using carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Miyazono, Nobuaki; Inoue, Hiroki; Ueno, Kazuto; Nishida, Hirotoshi; Kanetsuki, Ichirou; Miyake, Satoshi; Nakajo, Masayuki [Kagoshima Univ. (Japan). Faculty of Medicine

    1995-04-01

    Carbon dioxide (CO{sub 2}) intra-arterial subtraction angiography (IADSA) was performed in 31 patients with various hepatobiliary disease. The injection sites of CO{sub 2} were proper hepatic artery (10/31; group A), segmental hepatic artery (18/31; group B), and peripheral inferior phrenic artery (3/31; group C), respectively. In group A, only the third order branches of the portal venous system were visualized anterogradely in 8 of 10 patients. In group B, the microcatheter was placed coaxially through a 5 French guiding catheter at the main arterial supply of the tumor in 7 patients and at the peripheral segmental branch of the hepatic artery in 11 patients. The portal venous system was visualized retrogradely in all of the patients regardless of the injection site. The injected CO{sub 2} may flow back into the portal vein through the anastmosis known as the peribiliary or periportal plexus. In group C, not only the portal vein but also the pulmonary artery or pericardial vein were visualized by this method. CO{sub 2}-IADSA was useful to image the minute communications between the various vessels, which have been not hitherto visualized by iodinated contrast medium. (author).

  9. Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease.

    Science.gov (United States)

    Al-Bachari, Sarah; Parkes, Laura M; Vidyasagar, Rishma; Hanby, Martha F; Tharaken, Vivek; Leroi, Iracema; Emsley, Hedley C A

    2014-01-01

    Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD.

  10. Bay of Fundy tidal energy : a response to the strategic environmental assessment

    International Nuclear Information System (INIS)

    2008-06-01

    Tidal in-stream energy conversion is an emerging technology to harness sea power. These energy conversion devices are similar to underwater windmills. The government of Nova Scotia is interested in understanding the potential effects of these devices on the Bay of Fundy. As a result, it commissioned a strategic environmental assessment (SEA) that was completed in the spring of 2008. This document presented a response to the SEA. It discussed Nova Scotia's specific approach to tidal energy as well as the province's broader approach to marine renewable energy in the Bay of Fundy, with specific responses to each recommendation in the SEA. The energy context was presented, with particular reference to energy strategy; emissions; legal requirements; production costs; and carbon costs. The report also discussed tidal lagoon technology as well as a demonstration facility called the Fundy Tidal Energy Centre. The objectives of the SEA were also described and recommendations were presented. Recommendations were grouped under several key themes such as sustainability principles; allowing the demonstration of tidal in-stream energy conversion (TISEC) technologies; marine renewable energy legislation; research program; Mi'kmaq ecological knowledge study; provincial standard for ecological data; Bay of Fundy socioeconomic background study; marine renewable energy demonstration program; siting demonstration projects; and environmental assessment of the demonstration facility. figs

  11. A Novel Approach to the Identification of Compromised Pulmonary Systems in Smokers by Exploiting Tidal Breathing Patterns

    Directory of Open Access Journals (Sweden)

    Raj Rakshit

    2018-04-01

    Full Text Available Smoking causes unalterable physiological abnormalities in the pulmonary system. This is emerging as a serious threat worldwide. Unlike spirometry, tidal breathing does not require subjects to undergo forceful breathing maneuvers and is progressing as a new direction towards pulmonary health assessment. The aim of the paper is to evaluate whether tidal breathing signatures can indicate deteriorating adult lung condition in an otherwise healthy person. If successful, such a system can be used as a pre-screening tool for all people before some of them need to undergo a thorough clinical checkup. This work presents a novel systematic approach to identify compromised pulmonary systems in smokers from acquired tidal breathing patterns. Tidal breathing patterns are acquired during restful breathing of adult participants. Thereafter, physiological attributes are extracted from the acquired tidal breathing signals. Finally, a unique classification approach of locally weighted learning with ridge regression (LWL-ridge is implemented, which handles the subjective variations in tidal breathing data without performing feature normalization. The LWL-ridge classifier recognized compromised pulmonary systems in smokers with an average classification accuracy of 86.17% along with a sensitivity of 80% and a specificity of 92%. The implemented approach outperformed other variants of LWL as well as other standard classifiers and generated comparable results when applied on an external cohort. This end-to-end automated system is suitable for pre-screening people routinely for early detection of lung ailments as a preventive measure in an infrastructure-agnostic way.

  12. A Novel Approach to the Identification of Compromised Pulmonary Systems in Smokers by Exploiting Tidal Breathing Patterns.

    Science.gov (United States)

    Rakshit, Raj; Khasnobish, Anwesha; Chowdhury, Arijit; Sinharay, Arijit; Pal, Arpan; Chakravarty, Tapas

    2018-04-25

    Smoking causes unalterable physiological abnormalities in the pulmonary system. This is emerging as a serious threat worldwide. Unlike spirometry, tidal breathing does not require subjects to undergo forceful breathing maneuvers and is progressing as a new direction towards pulmonary health assessment. The aim of the paper is to evaluate whether tidal breathing signatures can indicate deteriorating adult lung condition in an otherwise healthy person. If successful, such a system can be used as a pre-screening tool for all people before some of them need to undergo a thorough clinical checkup. This work presents a novel systematic approach to identify compromised pulmonary systems in smokers from acquired tidal breathing patterns. Tidal breathing patterns are acquired during restful breathing of adult participants. Thereafter, physiological attributes are extracted from the acquired tidal breathing signals. Finally, a unique classification approach of locally weighted learning with ridge regression (LWL-ridge) is implemented, which handles the subjective variations in tidal breathing data without performing feature normalization. The LWL-ridge classifier recognized compromised pulmonary systems in smokers with an average classification accuracy of 86.17% along with a sensitivity of 80% and a specificity of 92%. The implemented approach outperformed other variants of LWL as well as other standard classifiers and generated comparable results when applied on an external cohort. This end-to-end automated system is suitable for pre-screening people routinely for early detection of lung ailments as a preventive measure in an infrastructure-agnostic way.

  13. Tidal Dwarf Galaxies: Disc Formation at \\(z\\simeq0\\

    Directory of Open Access Journals (Sweden)

    Federico Lelli

    2015-11-01

    Full Text Available Collisional debris around interacting and post-interacting galaxies often display condensations of gas and young stars that can potentially form gravitationally bound objects: Tidal Dwarf Galaxies (TDGs. We summarise recent results on TDGs, which are originally published in Lelli et al. (2015, A&A.We study a sample of six TDGs around three different interacting systems, using high-resolution HI observations from the Very Large Array. We find that the HI emission associated to TDGs can be described by rotating disc models. These discs, however, would have undergone less than one orbit since the time of the TDG formation, raising the question of whether they are in dynamical equilibrium. Assuming that TDGs are in dynamical equilibrium, we find that the ratio of dynamical mass to baryonic mass is consistent with one, implying that TDGs are devoid of dark matter. This is in line with the results of numerical simulations where tidal forces effectively segregate dark matter in the halo from baryonic matter in the disc, which ends up forming tidal tails and TDGs.

  14. Carbon black nanoparticles and vascular dysfunction in cultured endothelial cells and artery segments

    DEFF Research Database (Denmark)

    Vesterdal, Lise K; Mikkelsen, Lone; Folkmann, Janne K

    2012-01-01

    Exposure to small size particulates is regarded as a risk factor for cardiovascular disease. We investigated effects of exposure to nanosized carbon black (CB) in human umbilical vein endothelial cells (HUVECs) and segments of arteries from rodents. The CB exposure was associated with increased......, whereas it did not alter the mitochondrial enzyme activity (WST-1) or the nitric oxide level in HUVECs. Incubation of aorta segments with 10µg/ml of CB increased the endothelial-dependent vasorelaxation, induced by acetylcholine, and shifted the endothelium-independent vasorelaxation, induced by sodium...... nitroprusside, towards a decreased sensitivity. In mesenteric arteries, the exposure to 10µg/ml was associated with a reduced pressure-diameter relationship. Incubation with 100µg/ml CB significantly decreased both acetylcholine and sodium nitroprusside responses as well as decreased the receptor...

  15. Cerebral vasomotor reactivity: steady-state versus transient changes in carbon dioxide tension.

    Science.gov (United States)

    Brothers, R Matthew; Lucas, Rebekah A I; Zhu, Yong-Sheng; Crandall, Craig G; Zhang, Rong

    2014-11-01

    Cerebral vasomotor reactivity (CVMR) to changes in arterial carbon dioxide tension (P aCO 2) is assessed during steady-state or transient changes in P aCO 2. This study tested the following two hypotheses: (i) that CVMR during steady-state changes differs from that during transient changes in P aCO 2; and (ii) that CVMR during rebreathing-induced hypercapnia would be blunted when preceded by a period of hyperventilation. For each hypothesis, end-tidal carbon dioxide tension (P ET , CO 2) middle cerebral artery blood velocity (CBFV), cerebrovascular conductance index (CVCI; CBFV/mean arterial pressure) and CVMR (slope of the linear regression between changes in CBFV and CVCI versus P ET , CO 2) were assessed in eight individuals. To address the first hypothesis, measurements were made during the following two conditions (randomized): (i) steady-state increases in P ET , CO 2 of 5 and 10 Torr above baseline; and (ii) rebreathing-induced transient breath-by-breath increases in P ET , CO 2. The linear regression for CBFV versus P ET , CO 2 (P = 0.65) and CVCI versus P ET , CO 2 (P = 0.44) was similar between methods; however, individual variability in CBFV or CVCI responses existed among subjects. To address the second hypothesis, the same measurements were made during the following two conditions (randomized): (i) immediately following a brief period of hypocapnia induced by hyperventilation for 1 min followed by rebreathing; and (ii) during rebreathing only. The slope of the linear regression for CBFV versus P ET , CO 2 (P < 0.01) and CVCI versus P ET , CO 2 (P < 0.01) was reduced during hyperventilation plus rebreathing relative to rebreathing only. These results indicate that cerebral vasomotor reactivity to changes in P aCO 2 is similar regardless of the employed methodology to induce changes in P aCO 2 and that hyperventilation-induced hypocapnia attenuates the cerebral vasodilatory responses during a subsequent period of rebreathing

  16. 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.

  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. 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.

  19. 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...

  20. Historical Morphological development of the Eastern Scheldt tidal basin (the Netherlands)

    NARCIS (Netherlands)

    Eelkema, M.; Wang, Z.B.; Stive, M.J.F.

    2009-01-01

    The Eastern Scheldt tidal basin has changed drastically in the past five centuries under the influence of both human interventions as well as extreme events. In 1530 A.D. a storm-surge inundated large parts in the landward end of the basin, and in the following four centuries local inhabitants

  1. 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...

  2. 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.

  3. 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.

  4. Temporal changes in carbon and nitrogen stable isotope ratios of macrozoobenthos on an artificial tidal flat facing a hypertrophic canal, inner Tokyo Bay

    International Nuclear Information System (INIS)

    Kanaya, Gen; Nakamura, Yasuo; Koizumi, Tomoyoshi; Yamada, Katsumasa; Koshikawa, Hiroshi; Kohzu, Ayato; Maki, Hideaki

    2013-01-01

    Highlights: • Temporal changes in food web structure were analyzed in a tidal flat in a hypertrophic coastal bay. • Microphytobenthos mainly supported the benthic food web throughout seasons. • Phytoplankton and terrestrial detritus were utilized after red tides and urban runoffs. • Seasonal changes in consumer-δ 15 N was much larger in inner Tokyo Bay than in other estuaries. • This study showed specific characteristics of benthic food web in highly urbanized estuaries. -- Abstract: Temporal changes in benthic food web structure were analyzed in an artificial tidal flat in inner Tokyo Bay, Japan, using carbon and nitrogen stable isotope ratios (δ 13 C and δ 15 N). Microphytobenthos were the most important food sources of macrozoobenthos, due to high microphytobenthic biomass on the tidal flat, while phytoplankton in canal water (canal POM PP ), terrestrial materials from urban surface runoff (canal POM TM ), and marsh plants were less important. Dietary contribution of microphytobenthos was highest in April to June, while decreased towards December owing to the supply of canal POM PP and canal POM TM following red tides and heavy rainfall events in summer to fall. Temporal changes in δ 15 N (Δδ 15 N) of consumer corresponded well to the 15 N-enrichment in canal POM PP in summer. A meta-analysis showed that the consumer-Δδ 15 N was considerably larger in inner Tokyo Bay than those in other estuaries, which may be a specific characteristic of benthic food web in highly urbanized estuaries

  5. 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

  6. 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.

  7. Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats

    Science.gov (United States)

    Henderson, Fraser; May, Walter J.; Gruber, Ryan B.; Discala, Joseph F.; Puscovic, Veljko; Young, Alex P.; Baby, Santhosh M.; Lewis, Stephen J.

    2015-01-01

    This study determined the effects of the peripherally restricted µ-opiate receptor (µ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25 µg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5 mg/kg of NLXmi but was attenuated by a 5.0 mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5 mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5 mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral µ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. PMID:24284037

  8. 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

  9. 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.

  10. Within-breath arterial PO2 oscillations in an experimental model of acute respiratory distress syndrome.

    Science.gov (United States)

    Williams, E M; Viale, J P; Hamilton, R M; McPeak, H; Sutton, L; Hahn, C E

    2000-09-01

    Tidal ventilation causes within-breath oscillations in alveolar oxygen concentration, with an amplitude which depends on the prevailing ventilator settings. These alveolar oxygen oscillations are transmitted to arterial oxygen tension, PaO2, but with an amplitude which now depends upon the magnitude of venous admixture or true shunt, QS/QT. We investigated the effect of positive end-expiratory pressure (PEEP) on the amplitude of the PaO2 oscillations, using an atelectasis model of shunt. Blood PaO2 was measured on-line with an intravascular PaO2 sensor, which had a 2-4 s response time (10-90%). The magnitude of the time-varying PaO2 oscillation was titrated against applied PEEP while tidal volume, respiratory rate and inspired oxygen concentration were kept constant. The amplitude of the PaO2 oscillation, delta PaO2, and the mean PaO2 value varied with the level of PEEP applied. At zero PEEP, both the amplitude and the mean were at their lowest values. As PEEP was increased to 1.5 kPa, both delta PaO2 and the mean PaO2 increased to a maximum. Thereafter, the mean PaO2 increased but delta PaO2 decreased. Clear oscillations of PaO2 were seen even at the lowest mean PaO2, 9.5 kPa. Conventional respiratory models of venous admixture predict that these PaO2 oscillations will be reduced by the steep part of the oxyhaemoglobin dissociation curve if a constant pulmonary shunt exists throughout the whole respiratory cycle. The facts that the PaO2 oscillations occurred at all mean PaO2 values and that their amplitude increased with increasing PEEP suggest that QS/QT, in the atelectasis model, varies between end-expiration and end-inspiration, having a much lower value during inspiration than during expiration.

  11. 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 ...

  12. 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

  13. 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

  14. 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

  15. 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.

  16. Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

    Directory of Open Access Journals (Sweden)

    Laura A Cagle

    Full Text Available Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury.To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation.5-12 week-old female BALB/c mice (n = 85 were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg or high tidal volume (15 ml/kg with or without positive end-expiratory pressure and recruitment maneuvers.Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation.Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours and lung injury worsens with longer-term ventilation (4 hrs. Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide

  17. Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model

    Science.gov (United States)

    Franzi, Lisa M.; Linderholm, Angela L.; Last, Jerold A.; Adams, Jason Y.; Harper, Richart W.

    2017-01-01

    Background Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury. Objectives To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation. Methods 5–12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers. Results Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation. Conclusions Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points

  18. Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

    Science.gov (United States)

    Cagle, Laura A; Franzi, Lisa M; Linderholm, Angela L; Last, Jerold A; Adams, Jason Y; Harper, Richart W; Kenyon, Nicholas J

    2017-01-01

    Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury. To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation. 5-12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers. Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation. Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency

  19. Skin autofluorescence is increased in patients with carotid artery stenosis and peripheral artery disease

    NARCIS (Netherlands)

    Noordzij, Marjon J.; Lefrandt, Joop D.; Loeffen, Erik A. H.; Saleem, Ben R.; Meerwaldt, Robbert; Lutgers, Helen L.; Smit, Andries J.; Zeebregts, Clark J.

    Advanced glycation end products (AGEs) have a pivotal role in atherosclerosis. We evaluated skin autofluorescence (SAF), a non-invasive measurement of tissue AGE accumulation, in patients with carotid artery stenosis with and without coexisting peripheral artery occlusive disease (PAOD). SAF was

  20. 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.

  1. 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.

  2. Arterial oxygen tension and pulmonary ventilation in horses placed in the Anderson Sling suspension system after a period of lateral recumbency and anaesthetised with constant rate infusions of romifidine and ketamine.

    Science.gov (United States)

    François, I; Lalèyê, F-X; Micat, M; Benredouane, K; Portier, K

    2014-09-01

    Some controversy exists over whether or not horses' recovery and cardiopulmonary function are affected by suspension in slings. To measure arterial oxygen tension and pulmonary ventilation in anaesthetised horses placed in a standing position in an Anderson Sling (AS) after a period of right lateral recumbency (RLR). Randomised crossover experimental study. Six Standardbred horses were anaesthetised twice. Catheters were inserted into the right jugular vein and the left carotid artery. After premedication with romifidine, anaesthesia was induced with diazepam and ketamine. Following 50 min in RLR, horses were maintained in either RLR or AS for an additional 60 min through to recovery. Anaesthesia was maintained i.v. with a constant rate infusion of romifidine and ketamine. Heart rate, respiratory rate, mean arterial pressure, expiratory tidal volume, minute volumes and end tidal CO2 were monitored continuously. Venous and arterial bloods were sampled for lactate concentration, creatine kinase activity and blood gas analysis before premedication, after induction, every 20 min for 100 min, as soon as the horse was standing (TR), and 24 h later. The data were averaged within 2 anaesthetic periods: P1, 0-20 min; and P2, 40-100 min. During P2, horses in the RLR group had lower arterial oxygen tension (P = 0.001), higher alveolar-arterial oxygen tension gradient (P = 0.005), higher respiratory rate (P = 0.04) and higher minute volumes (P = 0.04) than horses in the AS group. Arterial CO2 tension and mean arterial pressure increased in the AS group during P2 (P = 0.01 and 0.02 respectively). The recoveries were judged better in the AS group than in the RLR group (P = 0.01). During TR, lactate were higher in the RLR group than in the AS group (P = 0.007). Creatine kinase activities were higher in the AS group at 24 h vs. TR (P = 0.02). Anderson Sling suspension after a period of recumbency improves cardiopulmonary function and recovery quality in horses and

  3. 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)

  4. End-tidal CO₂ detection of an audible heart rate during neonatal cardiopulmonary resuscitation after asystole in asphyxiated piglets.

    Science.gov (United States)

    Chalak, Lina F; Barber, Chad A; Hynan, Linda; Garcia, Damian; Christie, Lucy; Wyckoff, Myra H

    2011-05-01

    Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO₂ (ETCO₂) monitoring may provide a continuous noninvasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO₂ value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO₂ that is associated with ROSC after asphyxia-induced asystole. Neonatal swine (n = 46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O₂ followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 s, and ETCO₂ was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO₂ values, where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO₂ cut-off value of 14 mm Hg is the most sensitive ETCO₂ value with the least false positives. When using ETCO₂ to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO₂ ≥ 14 mm Hg is achieved. Correlation during human neonatal CPR needs further investigation.

  5. Self-assembly of the second-generation of nitroaryl-ended dendrons onto carbon

    International Nuclear Information System (INIS)

    Farías, E.D.; Paez, J.I.; Strumia, M.C.; Baruzzi, A.M.; Passeggi Jr, M.C.G.; Brunetti, V.

    2014-01-01

    Graphical abstract: - Abstract: We report the self-assembly of the second-generation of nitroaryl-ended dendrons onto carbon surfaces. The immobilized layer was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy and atomic force microscopy (AFM). The response was analyzed in comparison to the first-generation dendron behavior. Reduction of both layers generates the hydroxylamine product. The resulting redox-active layer exhibits a well-behaved redox response for the adsorbed nitroso/hydroxylamine couple. The thermodynamic of the adsorption of both dendrons on glassy carbon electrodes was also studied by CV. The Frumkin adsorption isotherm was the best to describe the specific interactions. The AFM images showed a network film formation with embedded aggregates that completely covered the carbon surface. The average height suggests a tilted preferential adsorption for both molecules

  6. 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.)

  7. 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.

  8. Avaliação da correlação entre o dióxido de carbono expirado e o débito cardíaco em pacientes submetidos à cirurgia cardíaca com circulação extracorpórea Evaluación de la correlación entre el dióxido de carbono expirado y el débito cardíaco en pacientes sometidos a la cirugía cardíaca con circulación extracorpórea Correlation between end-tidal carbon dioxide levels and cardiac output during cardiac surgery with cardiopulmonary bypass

    Directory of Open Access Journals (Sweden)

    Karina Takesaki Miyaji

    2004-10-01

    flujo sanguíneo pulmonar (circulación. Cuando el metabolismo y la ventilación son constantes, el CO2 expirado refleja el flujo sanguíneo pulmonar y, de esta forma, el débito cardíaco (DC. Este estudio tiene como objetivo la evaluación de la correlación entre el dióxido de carbono expirado (P ET CO2 y el débito cardíaco en pacientes sometidos a la cirugía cardíaca con circulación extracorpórea (CEC. MÉTODO: Fueron estudiados 25 pacientes sometidos a la cirugía de revascularización miocárdica con CEC. Después de la intubación traqueal tuvo inicio la monitorización de la P ET CO2. La determinación del débito cardíaco (DC fue hecha por método de termodiluición con el uso de catéter de Swan-Ganz y la PaCO2 fue evaluada a través de gasometría arterial. Los parámetros del estudio fueron evaluados en cuatro momentos: luego después de la inducción de la anestesia general; antes de la circulación extracorpórea, al término de la circulación extracorpórea y al final de la cirugía. RESULTADOS: El teste estadístico no demostró una correlación entre el CO2 expirado y el DC, así como el gradiente de dióxido de carbono arterial y expirado (Ga-eCO2 y el DC. Fue encontrada correlación entre la variación de los valores de la P ET CO2, Ga-eCO2 y DC en relación al basal antes de la CEC con pérdida de la correlación después de la CEC hasta el final de la cirugía. CONCLUSIONES: En este estudio, donde se evalúan pacientes sometidos a cirugía cardíaca con CEC, las alteraciones de relación ventilación/perfusión ocurridas a lo largo del procedimiento son, probablemente, los factores determinantes de la diminución de la correlación entre el débito cardíaco y el valor de dióxido de carbono expirado.BACKGROUND AND OBJECTIVES: End-tidal carbon dioxide (P ET CO2 not only reflects pulmonary ventilation but also carbon dioxide production (metabolism and pulmonary blood supply (circulation. During constant metabolism and ventilation, P ET CO2

  9. 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.

  10. 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

  11. 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...

  12. Influence of smoking and obesity on alveolar-arterial gas pressure differences and dead space ventilation at rest and peak exercise in healthy men and women.

    Science.gov (United States)

    Gläser, Sven; Ittermann, Till; Koch, Beate; Schäper, Christoph; Felix, Stephan B; Völzke, Henry; Könemann, Raik; Ewert, Ralf; Hansen, James E

    2013-06-01

    Besides exercise intolerance, the assessment of ventilatory and perfusion adequacy allows additional insights in the disease pathophysiology in many cardiovascular or pulmonary diseases. Valid measurements of dead space/tidal volume ratios (VD/VT), arterial (a') - end-tidal (et) carbon dioxide (CO2) and oxygen (O2) pressure differences (p(a'-et)CO2) and (p(et-a')O2), and alveolar (A)-a' O2 pressure differences (p(A-a')O2) require using blood samples in addition to gas exchange analyses on a breath-by-breath-basis. Smoking and nutritional status are also important factors in defining disorders. Using a large healthy population we considered the impact of these factors to develop useful prediction equations. Incremental cycle exercise protocols were applied to apparently healthy volunteer adults who did not have structural heart disease or echocardiographic or lung function pathologies. Age, height, weight, and smoking were analysed for their influence on the target parameters in each gender. Reference values were determined by regression analyses. The final study sample consisted of 476 volunteers (190 female), aged 25-85 years. Smoking significantly influences p(A-a')O2 and p(a'-et)CO2 at rest and peak exercise, and VD/VT during exercise. Obesity influences upper limits of VD/VT, p(a'-et)CO2 and p(et-a')O2 at rest as well as p(A-a')O2 and p(et-a')O2 at exercise. Reference equations for never-smokers as well as for apparently healthy smokers considering influencing factors are given. Gender, age, height, weight, and smoking significantly influence gas exchange. Considering all of these factors this study provides a comprehensive set of reference equations derived from a large number of participants of a population-based study. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. 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

  14. 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...

  15. 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

  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. Recent scientific advances and their implications for sand management near San Francisco, California: the influences of the ebb tidal delta

    Science.gov (United States)

    Hanes, Daniel M.; Barnard, Patrick L.; Dallas, Kate; Elias, Edwin; Erikson, Li H.; Eshleman, Jodi; Hansen, Jeff; Hsu, Tian Jian; Shi, Fengyan

    2011-01-01

    Recent research in the San Francisco, California, U.S.A., coastal region has identified the importance of the ebb tidal delta to coastal processes. A process-based numerical model is found to qualitatively reproduce the equilibrium size and shape of the delta. The ebb tidal delta itself has been contracting over the past century, and the numerical model is applied to investigate the sensitivity of the delta to changes in forcing conditions. The large ebb tidal delta has a strong influence upon regional coastal processes. The prominent bathymetry of the ebb tidal delta protects some of the coast from extreme storm waves, but the delta also focuses wave energy toward the central and southern portions of Ocean Beach. Wave focusing likely contributes to a chronic erosion problem at the southern end of Ocean Beach. The ebb tidal delta in combination with non-linear waves provides a potential cross-shore sediment transport pathway that probably supplies sediment to Ocean Beach.

  18. 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.

  19. A water-quality study of the tidal Potomac River and Estuary: An overview

    Science.gov (United States)

    Callendar, Edward; Carter, Virginia; Hahl, D.C.; Hitt, Kerie; Schultz, Barbara I.

    1984-01-01

    The U.S. Geological Survey began a 5-year interdisciplinary study of the tidal Potomac River and Estuary in October of 1977. The objectives of the study are: (1) to provide a basic understanding of physical, chemical, and biological processes; (2) to develop flow and transport models to predict the movement and fate of nutrients and algaes and (3) to develop efficient techniques for the study of tidal rivers and estuaries. The ultimate goal is to aid water-quality decision-making for the tidal Potomac River and Estuary. The study is being conducted by scientists from many disciplines involved in 14 interrelated studies. These scientists are addressing five major problem areas: nutrient enrichment, algal blooms, dissolved oxygen, sedimentation, and effects of water quality on living resources. Preliminary results show that treatment of sewage has reduced the concentration load of organic carbon and phosphorus below that of the 1960's and 1970's, and changed the form of dissolved nitrogen in the tidal river. Concentrations of chlorophyll a during the study period were lower than those experienced during the massive algal blooms of the 1960's. Dissolved oxygen concentrations fluctuate in response to changes in algal populations, but remain above the Environmental Protection Agency limits during the summer low-flow period. Sedimentation rates have accelerated during the past 50-70 years due to urbanization and farming. Asian clams have recently invaded the tidal river; submersed aquatic vegetation has declined since the early 1900's, but conditions may now favor its return.

  20. Absent end diastolic flow of umbilical artery Doppler: pregnancy outcome in 62 cases.

    Science.gov (United States)

    Poulain, P; Palaric, J C; Milon, J; Betremieux, P; Proudhon, J F; Signorelli, D; Grall, J Y; Giraud, J R

    1994-02-01

    We retrospectively studied the outcome of pregnancy in 62 cases of absent end diastolic flow (AEDF) of umbilical artery Doppler flow velocity waveform. The history of pregnancies revealed that nearly all were of high risk. Many cases presented cerebral (65%) or uterine (55.5%) Doppler flow abnormalities, or both (38%). We noted 10 fetal deaths and decided 7 pregnancy terminations. Malformation and chromosomal defect rate was 16%. We noted 44 (71%) live-births, a very high rate of cesarean section (86%), prematurity (75%), small for gestational age (39%). Forty-five percent of the neonates had a 1-min Apgar score under 7, which dropped to 27% at 5 min. Neonate mortality rate was 6.9% and the total mortality rate was 34% (21/62). Morbidity was significant (7 cases with severe morbidity, 2 cases with chromosomal abnormality of poor prognosis). We compared different sub-groups with a view to looking for some prenatal factors which predict poor neonatal outcome in case of AEDF.

  1. 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.

  2. 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.

  3. The anterior temporal artery: an underutilized but robust donor for revascularization of the distal middle cerebral artery.

    Science.gov (United States)

    Tayebi Meybodi, Ali; Lawton, Michael T; Griswold, Dylan; Mokhtari, Pooneh; Payman, Andre; Benet, Arnau

    2017-10-01

    OBJECTIVE The anterior temporal artery (ATA) supplies an area of the brain that, if sacrificed, does not cause a noticeable loss of function. Therefore, the ATA may be used as a donor in intracranial-intracranial (IC-IC) bypass procedures. The capacities of the ATA as a donor have not been studied previously. In this study, the authors assessed the feasibility of using the ATA as a donor for revascularization of different segments of the distal middle cerebral artery (MCA). METHODS The ATA was studied in 15 cadaveric specimens (8 heads, excluding 1 side). First, the cisternal segment of the artery was untethered from arachnoid adhesions and small branches feeding the anterior temporal lobe and insular cortex, to evaluate its capacity for a side-to-side bypass to insular, opercular, and cortical segments of the MCA. Any branch entering the anterior perforated substance was preserved. Then, the ATA was cut at the opercular-cortical junction and the capacity for an end-to-side bypass was assessed. RESULTS From a total of 17 ATAs, 4 (23.5%) arose as an early MCA branch. The anterior insular zone and the frontal parasylvian cortical arteries were the best targets (in terms of mobility and caliber match) for a side-to-side bypass. Most of the insula was accessible for end-to-side bypass, but anterior zones of the insula were more accessible than posterior zones. End-to-side bypass was feasible for most recipient cortical arteries along the opercula, except for posterior temporal and parietal regions. Early ATAs reached significantly farther on the insular MCA recipients than non-early ATAs for both side-to-side and end-to-side bypasses. CONCLUSIONS The ATA is a robust arterial donor for IC-IC bypass procedures, including side-to-side and end-to-side techniques. The evidence provided in this work supports the use of the ATA as a donor for distal MCA revascularization in well-selected patients.

  4. 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.

  5. Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

    Directory of Open Access Journals (Sweden)

    Catherine E. Lovelock

    2017-05-01

    Full Text Available The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after disturbance the cumulative CO2 emitted from tidal marshes, mangrove forests, and seagrass beds were ~70–80% of the initial carbon stocks in the top meter of the sediment. Comparison of our estimates of CO2 emissions with empirical studies suggests that (1 assuming 50% of organic material moves to an oxic environment after disturbance gives rise to estimates that are similar to CO2 emissions reported for tidal marshes; (2 field measurements of CO2 emissions in disturbed mangrove forests were generally higher than our modeled emissions that assumed 50% of organic matter was deposited in oxic conditions, suggesting higher proportions of organic matter may be exposed to oxic conditions after disturbance in mangrove ecosystems; and (3 the generally low observed rates of CO2 emissions from disturbed seagrasses compared to our estimates, assuming removal of 50% of the organic matter to oxic environments, suggests that lower proportions may be exposed to oxic conditions in seagrass ecosystems. There are significant gaps in our knowledge of the fate of wetland sediment carbon in the marine environment after disturbance. Greater knowledge of the distribution, form, decomposition, and emission rates of wetland sediment carbon after disturbance would help to improve models.

  6. Low pre-treatment end-tidal CO2 predicts dropout from cognitive-behavioral therapy for anxiety and related disorders.

    Science.gov (United States)

    Tolin, David F; Billingsley, Amber L; Hallion, Lauren S; Diefenbach, Gretchen J

    2017-03-01

    Recent clinical trial research suggests that baseline low end-tidal CO 2 (ETCO 2 , the biological marker of hyperventilation) may predict poorer response to cognitive-behavioral therapy (CBT) for anxiety-related disorders. The present study examined the predictive value of baseline ETCO 2 among patients treated for such disorders in a naturalistic clinical setting. Sixty-nine adults with a primary diagnosis of a DSM-5 anxiety disorder, obsessive-compulsive disorder, or posttraumatic stress disorder completed a 4-min assessment of resting ETCO 2 , and respiration rate (the first minute was analyzed). Lower ETCO 2 was not associated with a diagnosis of panic disorder, and was associated with lower subjective distress ratings on certain measures. Baseline ETCO 2 significantly predicted treatment dropout: those meeting cutoff criteria for hypocapnia were more than twice as likely to drop out of treatment, and ETCO 2 significantly predicted dropout beyond other pre-treatment variables. Weekly measurement suggested that the lower-ETCO 2 patients who dropped out were not responding well to treatment prior to dropout. The present results, along with previous clinical trial data, suggest that lower pre-treatment ETCO 2 is a negative prognostic indicator for CBT for anxiety-related disorders. It is suggested that patients with lower ETCO 2 might benefit from additional intervention that targets respiratory abnormality. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. 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.

  8. 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.

  9. Greenland Tidal Pools as Hot Spots for Ecosystem Metabolism and Calcification

    KAUST Repository

    Duarte, Carlos M.; Krause-Jensen, Dorte

    2018-01-01

    twice a day. Meroplankton larvae are exposed to ocean acidification until they settle in vegetated tidal pools, where they benefit from the protection offered by the “macroalgae-carbonate saturation state” interaction favouring calcification rates.

  10. Greenland Tidal Pools as Hot Spots for Ecosystem Metabolism and Calcification

    KAUST Repository

    Duarte, Carlos M.

    2018-01-18

    twice a day. Meroplankton larvae are exposed to ocean acidification until they settle in vegetated tidal pools, where they benefit from the protection offered by the “macroalgae-carbonate saturation state” interaction favouring calcification rates.

  11. 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.

  12. 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

  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. Increased norepinephrine release from dog pulmonary artery caused by nitrous oxide

    International Nuclear Information System (INIS)

    Rorie, D.K.; Tyce, G.M.; Sill, J.C.

    1986-01-01

    The effects of nitrous oxide on the release and metabolism of norepinephrine (NE) at neuroeffector junctions in dog pulmonary artery were examined. Helical strips of artery were incubated in Krebs-Ringer solution containing L-( 3 H)NE and mounted for superfusion. The arterial strips were studied in the presence of 95% oxygen-5% carbon dioxide, 70% nitrogen-30% oxygen, or 70% nitrous oxide-30% oxygen. During the 60 min of each experiment, five samples of superfusion fluid were collected for analysis and the effluxes of ( 3 H)NE and its radiolabeled metabolites were measured before and during electrical stimulation and during recovery from stimulation. ( 3 H)Norepinephrine was separated from its metabolites in the superfusate and in extracts of artery by column chromatography and quantitated by liquid scintillation spectrometry. Nitrous oxide significantly increased the fractional loss of total radioactivity and the amount of NE in the superfusate both during resting conditions and during stimulation. Nitrous oxide had no effect on the proportions of radioactivity among metabolites of NE in the superfusate or on the profile of NE metabolites remaining in the tissue after experimentation. These findings are consistent with increased NE release as a direct effect of nitrous oxide on nerve endings

  15. Carbon Sequestration and Sedimentation in Mangrove Swamps Influenced by Hydrogeomorphic Conditions and Urbanization in Southwest Florida

    Directory of Open Access Journals (Sweden)

    Daniel A. Marchio

    2016-05-01

    Full Text Available This study compares carbon sequestration rates along two independent tidal mangrove creeks near Naples Bay in Southwest Florida, USA. One tidal creek is hydrologically disturbed due to upstream land use changes; the other is an undisturbed reference creek. Soil cores were collected in basin, fringe, and riverine hydrogeomorphic settings along each of the two tidal creeks and analyzed for bulk density, total organic carbon profiles, and sediment accretion. Radionuclides 137Cs and 210Pb were used to estimate recent sediment accretion and carbon sequestration rates. Carbon sequestration rates (mean ± standard error for seven sites in the two tidal creeks on the Naples Bay (98 ± 12 g-C m−2·year−1 (n = 18 are lower than published global means for mangrove wetlands, but consistent with other estimates from the same region. Mean carbon sequestration rates in the reference riverine setting were highest (162 ± 5 g-C m−2·year−1, followed by rates in the reference fringe and disturbed riverine settings (127 ± 6 and 125 ± 5 g-C m−2·year−1, respectively. The disturbed fringe sequestered 73 ± 10 g-C m−2·year−1, while rates within the basin settings were 50 ± 4 g-C m−2·year−1 and 47 ± 4 g-C m−2·year−1 for the reference and disturbed creeks, respectively. These data support our hypothesis that mangroves along a hydrologically disturbed tidal creek sequestered less carbon than did mangroves along an adjacent undisturbed reference creek.

  16. 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

  17. End of the Little Ice Age in the Alps forced by industrial black carbon

    OpenAIRE

    Painter, Thomas H.; Flanner, Mark G.; Kaser, Georg; Marzeion, Ben; VanCuren, Richard A.; Abdalati, Waleed

    2013-01-01

    The end of the Little Ice Age in the European Alps has long been a paradox to glaciology and climatology. Glaciers in the Alps began to retreat abruptly in the mid-19th century, but reconstructions of temperature and precipitation indicate that glaciers should have instead advanced into the 20th century. We observe that industrial black carbon in snow began to increase markedly in the mid-19th century and show with simulations that the associated increases in absorbed sunlight by black carbon...

  18. 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.

  19. 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

  20. Channel Capture as a Response to Anthropogenic Modification of a Tidal Landscape: Ganges-Brahmaputra-Meghna Delta, Southwest Bangladesh

    Science.gov (United States)

    Wilson, C.; Bain, R. L.; Goodbred, S. L., Jr.; Hale, R. P.

    2017-12-01

    Studies of tidal channel dynamics frequently emphasize "morphologically short" spatial scales (i.e., settings in which the cross-system tidal propagation time is negligible) or idealized single-channel planforms. In contrast, tides in the Ganges-Brahmaputra-Meghna Delta (GBMD) propagate more than 100 kilometers inland from the coast through a network of interconnected tidal estuaries, producing complex hydrodynamic behavior that remains poorly understood. Intense anthropogenic modification of the GBMD landscape further complicates tidally-driven, natural delta surface maintenance. Analyzing this system is particularly urgent given the current trend of rising sea level and its associated impacts on coastal communities.We present results from an ongoing field investigation of tidal waveform interaction and mass exchange between the Pussur and Shibsa Rivers, two large macrotidal estuaries in the southwestern GBMD. In the 1960s, construction of earthen embankments ("polders") eliminated regular tidal inundation for a vast region of the tidal platform, shrinking the Shibsa and Pussur basins by an estimated 1000 km2 and 700 km2, respectively. Conservation of mass predicts that a reduction in tidal basin area will decrease peak flow velocities and induce channel siltation; indeed, 100 km2 of secondary channels at the distal end of the tidal range have partly or fully closed in recent decades. The Pussur is likewise rapidly shoaling, restricting navigational access along a major shipping route. However, discharge and bathymetric datasets indicate that the adjacent Shibsa conveys three to four times more water than the Pussur and is actively scouring its bed, contrary to its predicted response to polder construction. Our field measurements are consistent with an ongoing channel capture event in which the Shibsa floods and drains a progressively greater portion of the former Pussur basin, allowing the Shibsa to widen and deepen despite the regional trend of channel

  1. 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.

  2. 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.

  3. Acute retroperitoneal bleeding due to inferior mesenteric artery aneurysm: Case report

    Directory of Open Access Journals (Sweden)

    Ferrón JA

    2010-06-01

    Full Text Available Abstract Background Visceral artery aneurysms (VAA, although uncommon, are increasingly being detected. We describe a case of spontaneous retroperitoneal hemorrhage from a ruptured IMA aneurysm associated with stenosis of the superior mesenteric artery (SMA and celiac trunk, successfully treated with surgery. Methods A 65-year-old man presented with abdominal pain and hypovolemic shock. Abdominal CT scan showed an aneurysm of the inferior mesenteric artery with retroperitoneal hematoma. In addition, an obstructive disease of the superior mesenteric artery and celiac axis was observed. Results Upon emergency laparotomy a ruptured inferior mesenteric artery aneurysm was detected. The aneurysm was excised and the artery reconstructed by end-to-end anastomosis. Conclusions This report discusses the etiology, presentation, diagnosis and case management of inferior mesenteric artery aneurysms.

  4. 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.

  5. 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

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

    NARCIS (Netherlands)

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

    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

  7. Color Doppler Indices of Orbital Arterial Flow in End-Stage Renal Disease Patients; Are the Changes Related to Chronic Hemodialysis or Chronic Renal Failure?

    International Nuclear Information System (INIS)

    Rokni Yazdi, Hadi; Faraji, Safoura; Ahmadi, Farokhlegha; Shahmirzae, Reza

    2012-01-01

    Endothelial injury is a well-known complication in chronic kidney disease (CKD) and hemodialysis. One of the sites in which early vascular changes may be detected is the retina. Of course, these flow changes may not be detected in ophthalmologic exams, but it seems that color Doppler sonography of retinal arteries may be helpful in these cases. In previous studies on CKD patients who underwent chronic hemodialysis,hemodynamic changes were noted in retinal arteries, but no study has been performed to determine which of the two processes (CKD or chronic hemodialysis) can produce these changes. In this study, we tried to answer this question. Doppler ultrasonography of the orbital vasculature including the ophthalmic artery and the central retinal artery was carried out in 17 patients (34 eyes) with chronic renal failure (CRF) who underwent hemodialysis, 17 patients (34 eyes)with CRF without a history of hemodialysis and 17 normal patients (34 eyes). The peak systolic velocity (PSV), end diastolic velocity (EDV) and resistance index were measured excluding hypertensive, diabetic patients and patients with cardiovascular disease. The mean PSV and EDV were lower only in the ophthalmic artery of CRF patients irrespective of the history of hemodialysis (PSV was 35.2 in hemodialysis, 38.8 in CRF and 51.6 in normal patients, P value = 0.001 and EDV was 7.4, 9.4, 11.8, respectively, P value =0.001) with no significant difference in the resistance index of the ophthalmic artery and other parameters [EDV, PSV, Resistance Index (RI)] in the central retinal artery. The mean PSV and DSV in the ophthalmic artery were lower only in the ophthalmic artery of CRF patients regardless of the history of hemodialysis. No significant difference in the resistance index of the ophthalmic artery and other parameters (EDV, PSV) of the central retinal artery were noted between different groups. These findings suggest that microvascular disease and endothelial cell dysfunction of the orbital

  8. 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.

  9. 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.

  10. 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.

  11. Effects of Low-Carbon Technologies and End-Use Electrification on Energy-Related Greenhouse Gases Mitigation in China by 2050

    Directory of Open Access Journals (Sweden)

    Zheng Guo

    2015-07-01

    Full Text Available Greenhouse gas emissions in China have been increasing in line with its energy consumption and economic growth. Major means for energy-related greenhouse gases mitigation in the foreseeable future are transition to less carbon intensive energy supplies and structural changes in energy consumption. In this paper, a bottom-up model is built to examine typical projected scenarios for energy supply and demand, with which trends of energy-related carbon dioxide emissions by 2050 can be analyzed. Results show that low-carbon technologies remain essential contributors to reducing emissions and altering emissions trends up to 2050. By pushing the limit of current practicality, emissions reduction can reach 20 to 28 percent and the advent of carbon peaking could shift from 2040 to 2030. In addition, the effect of electrification at end-use sectors is studied. Results show that electrifying transport could reduce emissions and bring the advent of carbon peaking forward, but the effect is less significant compared with low-carbon technologies. Moreover, it implies the importance of decarbonizing power supply before electrifying end-use sectors.

  12. Genome-wide transcriptional responses of Alteromonas naphthalenivorans SN2 to contaminated seawater and marine tidal flat sediment.

    Science.gov (United States)

    Jin, Hyun Mi; Jeong, Hye Im; Kim, Kyung Hyun; Hahn, Yoonsoo; Madsen, Eugene L; Jeon, Che Ok

    2016-02-18

    A genome-wide transcriptional analysis of Alteromonas naphthalenivorans SN2 was performed to investigate its ecophysiological behavior in contaminated tidal flats and seawater. The experimental design mimicked these habitats that either added naphthalene or pyruvate; tidal flat-naphthalene (TF-N), tidal flat-pyruvate (TF-P), seawater-naphthalene (SW-N), and seawater-pyruvate (SW-P). The transcriptional profiles clustered by habitat (TF-N/TF-P and SW-N/SW-P), rather than carbon source, suggesting that the former may exert a greater influence on genome-wide expression in strain SN2 than the latter. Metabolic mapping of cDNA reads from strain SN2 based on KEGG pathway showed that metabolic and regulatory genes associated with energy metabolism, translation, and cell motility were highly expressed in all four test conditions, probably highlighting the copiotrophic properties of strain SN2 as an opportunistic marine r-strategist. Differential gene expression analysis revealed that strain SN2 displayed specific cellular responses to environmental variables (tidal flat, seawater, naphthalene, and pyruvate) and exhibited certain ecological fitness traits -- its notable PAH degradation capability in seasonally cold tidal flat might be reflected in elevated expression of stress response and chaperone proteins, while fast growth in nitrogen-deficient and aerobic seawater probably correlated with high expression of glutamine synthetase, enzymes utilizing nitrite/nitrate, and those involved in the removal of reactive oxygen species.

  13. Assessing the risk of carbon dioxide emissions from blue carbon ecosystems

    KAUST Repository

    Lovelock, Catherine E.

    2017-05-15

    "Blue carbon" ecosystems, which include tidal marshes, mangrove forests, and seagrass meadows, have large stocks of organic carbon (C) in their soils. These carbon stocks are vulnerable to decomposition and - if degraded - can be released to the atmosphere in the form of CO. We present a framework to help assess the relative risk of CO emissions from degraded soils, thereby supporting inclusion of soil C into blue carbon projects and establishing a means to prioritize management for their carbon values. Assessing the risk of CO emissions after various kinds of disturbances can be accomplished through knowledge of both the size of the soil C stock at a site and the likelihood that the soil C will decompose to CO.

  14. 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 ...

  15. 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.

  16. 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

  17. A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Taiping; Yang, Zhaoqing

    2017-12-01

    Previous tidal energy projects in Puget Sound have focused on major deep channels such as Admiralty Inlet that have a larger power potential but pose greater technical challenges than minor tidal channels connecting to small sub-basins. This paper focuses on the possibility of extracting energy from minor tidal channels by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and calibrated for tidal elevations and currents. We examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. The model suggests that with the proposed level of energy extraction, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.

  18. 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

  19. Tidal Marsh Outwelling of Dissolved Organic Matter and Resulting Temporal Variability in Coastal Water Optical and Biogeochemical Properties

    Science.gov (United States)

    Tzortziou, Maria; Neale, Patrick J.; Megonigal, J. Patrick; Butterworth, Megan; Jaffe, Rudolf; Yamashita, Youhei

    2010-01-01

    Coastal wetlands are highly dynamic environments at the land-ocean interface where human activities, short-term physical forcings and intense episodic events result in high biological and chemical variability. Long being recognized as among the most productive ecosystems in the world, tidally-influenced coastal marshes are hot spots of biogeochemical transformation and exchange. High temporal resolution observations that we performed in several marsh-estuarine systems of the Chesapeake Bay revealed significant variability in water optical and biogeochemical characteristics at hourly time scales, associated with tidally-driven hydrology. Water in the tidal creek draining each marsh was sampled every hour during several semi-diurnal tidal cycles using ISCO automated samplers. Measurements showed that water leaving the marsh during ebbing tide was consistently enriched in dissolved organic carbon (DOC), frequently by more than a factor of two, compared to water entering the marsh during flooding tide. Estimates of DOC fluxes showed a net DOC export from the marsh to the estuary during seasons of both low and high biomass of marsh vegetation. Chlorophyll amounts were typically lower in the water draining the marsh, compared to that entering the marsh during flooding tide, suggesting that marshes act as transformers of particulate to dissolved organic matter. Moreover, detailed optical and compositional analyses demonstrated that marshes are important sources of optically and chemically distinctive, relatively complex, high molecular weight, aromatic-rich and highly colored dissolved organic compounds. Compared to adjacent estuarine waters, marsh-exported colored dissolved organic matter (CDOM) was characterized by considerably stronger absorption (more than a factor of three in some cases), larger DOC-specific absorption, lower exponential spectral slope, larger fluorescence signal, lower fluorescence per unit absorbance, and higher fluorescence at visible wavelengths

  20. 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

  1. VASOMOTOR ENDOTHELIAL FUNCTION AND MICROCIRCULATION IN ELDERLY PATIENTS WITH ISOLATED SYSTOLIC ARTERIAL HYPERTENSION: INFLUENCE OF "DRY" CARBONIC BATHS AND GENERAL LOW-FREQUENCY MAGNETOTHERAPY

    OpenAIRE

    Alypova, Elena

    2013-01-01

    Abstract. The comparative estimation of influence of the general low-frequency magnetotherapy (GLMT) and "dry" carbonic baths (DCB) on indicators of vasomotor endothelial function and microcirculation in elderly patients with isolated systolic (ISAH) arterial hypertension has been studied. The efficiency of application the combined use of the GLMT and "dry" carbonic baths DCB for correction of revealed disorders in comparing to the monovariant use of thees medical physical factors is establis...

  2. End-tidal CO2 Detection of an Audible Heart Rate During Neonatal Cardiopulmonary Resuscitation Following Asystole in Asphyxiated Piglets

    Science.gov (United States)

    Chalak, Lina F.; Barber, Chad A.; Hynan, Linda; Garcia, Damian; Christie, Lucy; Wyckoff, Myra H.

    2011-01-01

    Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO2 (ETCO2) monitoring may provide a continuous non-invasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO2 value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO2 that is associated with ROSC following asphyxia-induced asystole. Neonatal swine (n=46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O2 followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 sec and ETCO2 was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO2 values where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO2 cut off value of 14 mmHg is the most sensitive ETCO2 value with the least false positives. When using ETCO2 to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO2 ≥14 mmHg is achieved. Correlation during human neonatal CPR needs further investigation. PMID:21283051

  3. Mercury dynamics in a San Francisco estuary tidal wetland: assessing dynamics using in situ measurements

    Science.gov (United States)

    Bergamaschi, Brian A.; Fleck, Jacob A.; Downing, Bryan D.; Boss, Emmanuel; Pellerin, Brian A.; Ganju, Neil K.; Schoellhamer, David H.; Byington, Amy A.; Heim, Wesley A.; Stephenson, Mark; Fujii, Roger

    2012-01-01

    We used high-resolution in situ measurements of turbidity and fluorescent dissolved organic matter (FDOM) to quantitatively estimate the tidally driven exchange of mercury (Hg) between the waters of the San Francisco estuary and Browns Island, a tidal wetland. Turbidity and FDOM—representative of particle-associated and filter-passing Hg, respectively—together predicted 94 % of the observed variability in measured total mercury concentration in unfiltered water samples (UTHg) collected during a single tidal cycle in spring, fall, and winter, 2005–2006. Continuous in situ turbidity and FDOM data spanning at least a full spring-neap period were used to generate UTHg concentration time series using this relationship, and then combined with water discharge measurements to calculate Hg fluxes in each season. Wetlands are generally considered to be sinks for sediment and associated mercury. However, during the three periods of monitoring, Browns Island wetland did not appreciably accumulate Hg. Instead, gradual tidally driven export of UTHg from the wetland offset the large episodic on-island fluxes associated with high wind events. Exports were highest during large spring tides, when ebbing waters relatively enriched in FDOM, dissolved organic carbon (DOC), and filter-passing mercury drained from the marsh into the open waters of the estuary. On-island flux of UTHg, which was largely particle-associated, was highest during strong winds coincident with flood tides. Our results demonstrate that processes driving UTHg fluxes in tidal wetlands encompass both the dissolved and particulate phases and multiple timescales, necessitating longer term monitoring to adequately quantify fluxes.

  4. 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...

  5. Tidal and sub-tidal sea level variability at the northern shelf of the Brazilian Northeast Region.

    Science.gov (United States)

    Frota, Felipe F; Truccolo, Eliane C; Schettini, Carlos A F

    2016-09-01

    A characterization of the sea level variability at tidal and sub-tidal frequencies at the northern shore of the Brazilian Northeast shelf for the period 2009-2011 is presented. The sea level data used was obtained from the Permanent Geodetic Tide Network from the Brazilian Institute of Geography and Statistics for the Fortaleza gauge station. Local wind data was also used to assess its effects on the low-frequency sea level variability. The variability of the sea level was investigated by classical harmonic analysis and by morphology assessment over the tidal signal. The low frequencies were obtained by low-pass filtering. The tidal range oscillated with the highest value of 3.3 m during the equinox and the lowest value of 0.7 m during the solstice. Differences between the spring and neap tides were as high as 1 m. A total of 59 tidal constituents were obtained from harmonic analysis, and the regional tide was classified as semi-diurnal pure with a form number of 0.11. An assessment of the monthly variability of the main tidal constituents (M2, S2, N2, O1, and K1) indicated that the main semi-diurnal solar S2 presented the highest variability, ranging from 0.21 to 0.41 m; it was the main element altering the form number through the years. The low frequency sea-level variability is negligible, although there is a persistent signal with an energy peak in the 10-15 day period, and it cannot be explained by the effects of local winds.

  6. 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.

  7. Resection-Reconstruction of Aberrant Right Hepatic Artery During Whipple Procedure (Pancreaticoduodenectomy).

    Science.gov (United States)

    Sayyed, Raza; Rehman, Iffat; Niazi, Imran Khalid; Yusuf, Muhammed Aasim; Syed, Aamir Ali; V, Faisal

    2016-06-01

    Aberrant hepatic arterial anatomy poses a challenge for the surgeon during Whipple procedure. Intraoperative injury to the aberrant vasculature results in hemorrhagic or ischemic complications involving the liver and biliary tree. We report a case of replaced right hepatic artery arising from the superior mesenteric artery in a patient with periampullary carcinoma of the pancreas, undergoing pancreaticoduodenectomy. The aberrant artery was found to be coursing through the pancreatic parenchyma. This is a rare vascular anomaly. Resection of the arterial segment and end-to-end anastomosis was fashioned. Intrapancreatic course of the replaced right hepatic artery is a rare anomaly and is best managed by preoperative identification on radiology and meticulous intra-operative dissection and preservation. However, for an intrapancreatic course, resection and reconstruction may occasionally be required.

  8. 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

  9. 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.

  10. Evaluation of tidal stream energy and its impacts on surrounding dynamics in the Eastern Region of Pingtan Island, China

    Science.gov (United States)

    Wu, He; Wang, Xin; Wang, Bingzhen; Bai, Yang; Wang, Peitao

    2017-11-01

    Using an improved FVCOM numerical model, combined with the momentum-sinking scheme based on the structural characteristics of specific turbines, this study analyzed the temporal and spatial distributions of tidal energy resources before and after the deployment of tidal turbines near Pingtan Island, China. Considering factors such as the distribution of tidal stream energy, bathymetry, topography, and the design parameters of the turbines, an appropriate location for a demonstration tidal turbine was selected and the corresponding energy resource was evaluated. Several sites with strong tidal streams were considered: south of the northern cape, east of the southern cape, and the southern end of Haitan Bay. The former was thought most suitable for the deployment of a tidal energy turbine, with projected power generation for approximately 470 h per month. The average power of this demonstration was about 2.4 kW, and the annual electricity output was approximately 17.47 MWh. The intervention of the turbine device had little influence on the near-field tidal stream or water level. The tidal stream was reduced slightly in the area south of the northern cape, although the effect weakened further from the turbine. Conversely, the velocity increased slightly on both sides of the demonstration site. The difference in current speed with and without the turbine was greater at slack tide than still tide. The influence of turbine operation on water level was minor. The method adopted in this study can be considered a reference for the selection of sites for the demonstration of tidal stream energy. However, the method is unable describe the dynamic characteristics of the turbulent flow surrounding the deployed turbines, which has an important role regarding the optimal designs of the turbine blade and pile foundations. Therefore, we will continue to work to improve this model in future research.

  11. 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

  12. End-tidal concentration of sevoflurane for preventing rocuronium-induced withdrawal of the arm in pediatric patients.

    Science.gov (United States)

    Yeom, Jong Hoon; Kim, Yong Oh; Lee, Jae Min; Jeon, Woo Jae

    2014-04-01

    During induction of general anesthesia, the intravenous injection of rocuronium is often associated with withdrawal movement of the arm due to pain, and this abrupt withdrawal may result in dislodgement of the venous catheter, injury, or inadequate injection of rocuronium. We performed this study to evaluate the 50 and 95% effective end-tidal concentrations of sevoflurane (ETsev) for preventing rocuronium-induced withdrawal of the arm. We conducted a prospective double-blind study in 31 pediatric patients. After free flow of lactated Ringer's IV fluid was confirmed, anesthesia was induced in the patients by using 2.5% thiopental sodium (4 mg/kg) and sevoflurane (4 vol%) with 6 L/min of oxygen. When the target ETsev was reached, preservative-free 1% lidocaine (1.5 mg/kg) was intravenously injected during manual venous occlusion and rocuronium (0.6 mg/kg) was injected after lidocaine injection under free-flow intravenous fluid. A nurse who was an investigator and was blinded to the ETsev injected the rocuronium. The nurse evaluated the response. Non-withdrawal movement was observed in 5 out of 11 patients with ETsev 3.0 vol% and in 5 out of 6 patients with ETsev 3.5 vol%. By Dixon's up-and-down method, the 50% effective concentration (EC50) of sevoflurane for non-withdrawal movement at rocuronium injection was 3.1 ± 0.4 vol%. A logistic regression curve of the probability of non-withdrawal movements showed that the 50% effective ETsev for abolishing withdrawal movement at rocuronium injection was 2.9 vol% (95% confidence interval [CI] 2.4-3.8 vol%) and the 95% effective ETsev was 4.3 vol% (95% CI 3.6-9.8 vol%). This study showed that the 50 and 95% effective ETsev that prevent withdrawal movement at rocuronium injection are 2.9 and 4.3 vol%, respectively.

  13. The impact of intervention strategies that target arterial stiffness in end-stage renal disease: a systematic review protocol.

    Science.gov (United States)

    Rodriguez, Rosendo A; Shea, Beverley; Hae, Richard; Burns, Kevin D

    2016-07-19

    Vascular damage contributes to the high cardiovascular morbidity and mortality in end-stage renal disease (ESRD). Increased aortic stiffness measured by carotid-femoral pulse wave velocity (cf-PWV) is a strong and independent predictor of the cardiovascular risk in ESRD patients. Recently, there has been considerable interest in developing strategies to lessen the progression of arterial stiffness in ESRD patients using cf-PWV as a tool to monitor therapeutic responses, but their benefit on the long-term cardiovascular risk is not known. Appraisal of the effects of existing stiffness-based interventions on the cf-PWV would facilitate selecting optimal therapies to be tested in randomized clinical trials. The aim of this systematic review will be to evaluate the impact of arterial stiffness-based interventions on the cf-PWV in ESRD patients. Secondarily, for each intervention, we will determine the minimal duration needed to achieve a significant reduction of cf-PWV, the minimal cf-PWV reduction threshold or effect size, and adverse events. This review will be conducted using MEDLINE, EMBASE, and EBM Reviews. We will select clinical trials and observational studies (cohort, case-control, and before/after studies and case series) that evaluated pharmacologic or non-pharmacologic interventions in which the primary effect is to improve structural and/or dynamic components of arterial stiffness in adults with stage 5 chronic kidney disease. The primary outcome of interest will be cf-PWV. Study selection and data collection will be performed by two reviewers. Validated tools will be used to assess the methodological quality and risk of bias among different study designs. We will describe all included citations according to study characteristics, methodological quality, and outcomes. Suitability for meta-analysis will be determined by the degree of clinical and statistical heterogeneity between studies. If appropriate, we will calculate effect estimates by obtaining the

  14. 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

  15. 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.

  16. 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...

  17. Arterial And Ventricular Elastance And Ventriculo-arterial Coupling In Asthmatic Children

    International Nuclear Information System (INIS)

    Ozkan, E. A.; Gecit, A.; Beysel, P.

    2016-01-01

    Objective: To compare arterial and ventricular end-systolic elastance and ventriculo-arterial coupling between asthma and healthy children and correlate these all three parameters with pulmonary function tests in subjects with asthma. Study Design: Across-sectional analytical study. Place and Duration of Study: Department of Pediatrics, Bozok University Medical Faculty,Yozgat, Turkey, from January 2012 to November 2014. Methodology: Transthoracic and Doppler echocardiography and pulmonary function tests in patients with asthma aged 7 - 12 years and control subjects. Forty stable asthma patients on prophylactic inhaled corticosteroids and 97 healthy subjects were investigated. Both groups were matched for age, gender, blood pressure, heart rate, body surface area, echocardiographic parameters and pulmonary function tests. Results: There was no difference regarding left ventricular elastance at end-systole derived by single beat/body surface area (Ees(sb)/BSA) between asthmatic patients and healthy children (2.59 ±1.29 mmHg/ml/m2, 2.43 ±1.28 mmHg/ml/m2 respectively, p=0.504), arterial elastance/BSA(Ea/BSA) (2.10 ±0.97, 1.75 ±0.89 respectively, p=0.041), and ventriculoarterial coupling (VAC) (0.83 ±0.13, 0.74 ±0.13, respectively, p < 0.001) were higher in asthmatic group than controls. There was no correlation between Ea, Ees (sb), VAC and pulmonary function tests. Conclusion: Arterial elastance increase and stiffness decrease in asthmatic patients. This may be due to using prophylactic inhaled corticosteroids. Using inhaled corticosteroids have protective effects against atherosclerosis. As a result of this higher arterial elastance, asthmatic children had higher VAC resulting in less efficient cardiovascular function. (author)

  18. 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

  19. 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

  20. 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.

  1. Arterial aging and arterial disease : interplay between central hemodynamics, cardiac work, and organ flow-implications for CKD and cardiovascular disease

    NARCIS (Netherlands)

    London, Gerard; Covic, Adrian; Goldsmith, David; Wiecek, Andrzej; Suleymanlar, Gultekin; Ortiz, Alberto; Massy, Ziad; Lindholm, Bengt; Martinez-Castelao, Alberto; Fliser, Danilo; Agarwal, Rajiv; Jager, Kitty J.; Dekker, Friedo W.; Blankestijn, Peter J.; Zoccali, Carmine

    Cardiovascular disease is an important cause of morbidity and mortality in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). All epidemiological studies have clearly shown that accelerated arterial and cardiac aging is characteristic of these populations. Arterial

  2. 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.

  3. Impact of Coastal Development and Marsh Width Variability on Groundwater Quality in Estuarine Tidal Creeks

    Science.gov (United States)

    Shanahan, M.; Wilson, A. M.; Smith, E. M.

    2017-12-01

    Coastal upland development has been shown to negatively impact surface water quality in tidal creeks in the southeastern US, but less is known about its impact on groundwater. We sampled groundwater in the upland and along the marsh perimeter of tidal creeks located within developed and undeveloped watersheds. Samples were analyzed for salinity, dissolved organic carbon, nitrogen and phosphorus concentrations. Groundwater samples collected from the upland in developed and undeveloped watersheds were compared to study the impact of development on groundwater entering the marsh. Groundwater samples collected along the marsh perimeter were analyzed to study the impact of marsh width variability on groundwater quality within each creek. Preliminary results suggest a positive correlation between salinity and marsh width in undeveloped watersheds, and a higher concentration of nutrients in developed versus undeveloped watersheds.

  4. 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.

  5. High tidal volume ventilation in infant mice.

    Science.gov (United States)

    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.

  6. Relationship between retinal blood flow and arterial oxygen.

    Science.gov (United States)

    Cheng, Richard W; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G; Fisher, Joseph A; Hudson, Chris

    2016-02-01

    Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content

  7. 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

  8. 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.

  9. 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.)

  10. Supplemental Carbon Dioxide Stabilizes the Upper Airway in Volunteers Anesthetized with Propofol.

    Science.gov (United States)

    Ruscic, Katarina Jennifer; Bøgh Stokholm, Janne; Patlak, Johann; Deng, Hao; Simons, Jeroen Cedric Peter; Houle, Timothy; Peters, Jürgen; Eikermann, Matthias

    2018-05-10

    Propofol impairs upper airway dilator muscle tone and increases upper airway collapsibility. Preclinical studies show that carbon dioxide decreases propofol-mediated respiratory depression. We studied whether elevation of end-tidal carbon dioxide (PETCO2) via carbon dioxide insufflation reverses the airway collapsibility (primary hypothesis) and impaired genioglossus muscle electromyogram that accompany propofol anesthesia. We present a prespecified, secondary analysis of previously published experiments in 12 volunteers breathing via a high-flow respiratory circuit used to control upper airway pressure under propofol anesthesia at two levels, with the deep level titrated to suppression of motor response. Ventilation, mask pressure, negative pharyngeal pressure, upper airway closing pressure, genioglossus electromyogram, bispectral index, and change in end-expiratory lung volume were measured as a function of elevation of PETCO2 above baseline and depth of propofol anesthesia. PETCO2 augmentation dose-dependently lowered upper airway closing pressure with a decrease of 3.1 cm H2O (95% CI, 2.2 to 3.9; P < 0.001) under deep anesthesia, indicating improved upper airway stability. In parallel, the phasic genioglossus electromyogram increased by 28% (23 to 34; P < 0.001). We found that genioglossus electromyogram activity was a significant modifier of the effect of PETCO2 elevation on closing pressure (P = 0.005 for interaction term). Upper airway collapsibility induced by propofol anesthesia can be reversed in a dose-dependent manner by insufflation of supplemental carbon dioxide. This effect is at least partly mediated by increased genioglossus muscle activity.

  11. 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.)

  12. Alveolar recruitment manoeuvre is safe in children prone to pulmonary hypertensive crises following open heart surgery: a pilot study.

    Science.gov (United States)

    Amorim, Erica de Freitas; Guimaraes, Viviane Assuncao; Carmona, Fabio; Carlotti, Ana Paula de Carvalho Panzeri; Manso, Paulo Henrique; Ferreira, Cesar Augusto; Klamt, Jyrson Guilherme; Vicente, Walter Villela de Andrade

    2014-05-01

    To test the tolerance and safety of an alveolar recruitment manoeuvre performed in the immediate postoperative period of corrective open heart surgery in children with congenital heart disease associated with excessive pulmonary blood flow and pulmonary arterial hypertension due to left-to-right shunt. Ten infants aged 1-24 months with congenital heart disease associated with excessive pulmonary blood flow and pulmonary artery hypertension (mean pulmonary artery pressure ≥ 25 mmHg) were evaluated. The alveolar recruitment manoeuvre was performed in the operating theatre right after skin closure, and consisted of three successive stages of 30 s each, intercalated by a 1-min interval of baseline ventilation. Positive end-expiratory pressure was set to 10 cmH2O in the first stage and to 15 cmH2O in the two last ones, while the peak inspiratory pressure was kept at to 30 cmH2O in the first stage and at 35 cmH2O in the latter ones. Haemodynamic and respiratory variables were recorded. There was a slight but significant increase in mean pulmonary artery pressure from baseline to Stage 3 (P = 0.0009), as well as between Stages 1 and 2 (P = 0.0001), and 1 and 3 (P = 0.001), with no significant difference between Stages 2 and 3 (P = 0.06). Upon completion of the third stage, there were significant increases in arterial haemoglobin saturation as measured by pulse oximetry (P = 0.0009), arterial blood partial pressure of oxygen (P = 0.04), venous blood oxygen saturation of haemoglobin (P = 0.03) and arterial oxygen partial pressure over inspired oxygen fraction ratio (P = 0.04). A significant reduction in arterial blood partial pressure of carbon dioxide (P = 0.01) and in end tidal carbon dioxide also occurred (P = 0.009). The manoeuvre was well tolerated and besides a slight and transitory elevation in mean pulmonary artery, no other adverse haemodynamic or ventilatory effect was elicited. The alveolar recruitment manoeuvre seemed to be safe and well tolerated immediately

  13. 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…

  14. Computer model analysis of the radial artery pressure waveform.

    Science.gov (United States)

    Schwid, H A; Taylor, L A; Smith, N T

    1987-10-01

    Simultaneous measurements of aortic and radial artery pressures are reviewed, and a model of the cardiovascular system is presented. The model is based on resonant networks for the aorta and axillo-brachial-radial arterial system. The model chosen is a simple one, in order to make interpretation of the observed relationships clear. Despite its simplicity, the model produces realistic aortic and radial artery pressure waveforms. It demonstrates that the resonant properties of the arterial wall significantly alter the pressure waveform as it is propagated from the aorta to the radial artery. Although the mean and end-diastolic radial pressures are usually accurate estimates of the corresponding aortic pressures, the systolic pressure at the radial artery is often much higher than that of the aorta due to overshoot caused by the resonant behavior of the radial artery. The radial artery dicrotic notch is predominantly dependent on the axillo-brachial-radial arterial wall properties, rather than on the aortic valve or peripheral resistance. Hence the use of the radial artery dicrotic notch as an estimate of end systole is unreliable. The rate of systolic upstroke, dP/dt, of the radial artery waveform is a function of many factors, making it difficult to interpret. The radial artery waveform usually provides accurate estimates for mean and diastolic aortic pressures; for all other measurements it is an inadequate substitute for the aortic pressure waveform. In the presence of low forearm peripheral resistance the mean radial artery pressure may significantly underestimate the mean aortic pressure, as explained by a voltage divider model.

  15. 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.

  16. Lung counting: Comparison of a four detector array that has either metal or carbon fiber end caps, and the effect on array performance characteristics

    International Nuclear Information System (INIS)

    Sabbir Ahmed, Asm; Kramer, Gary H.

    2011-01-01

    This study described the performance of an array of HPGe detectors, made by ORTEC. In the existing system, a metal end cap was used in the detector construction. In general, the natural metal contains some radioactive materials, create high background noises and signals during in vivo counting. ORTEC proposed a novel carbon fiber to be used in end cap, without any radio active content. This paper described the methodology of developing a model of the given HPGe array-detectors, comparing the detection efficiency and cross talk among the detectors using two end cap materials: either metal or carbon fiber and to provide a recommendation about the end cap material. The detector's counting efficiency were studied using point and plane sources. The cross talk among the array detectors were studied using a homogeneous attenuating medium made of tissue equivalent material. The cross talk was significant when single or multiple point sources (simulated to heterogeneous hot spots) were embedded inside the attenuating medium. With carbon fiber, the cross talk increased about 100% for photon energy at about 100 keV. For a uniform distribution of radioactive material, the cross talk increased about 5-10% when the end cap was made of carbon instead of steel. Metal end cap was recommended for the array of HPGe detectors.

  17. 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.

  18. 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)

  19. 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...

  20. 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...

  1. Weaning mechanical ventilation after off-pump coronary artery bypass graft procedures directed by noninvasive gas measurements.

    Science.gov (United States)

    Chakravarthy, Murali; Narayan, Sandeep; Govindarajan, Raghav; Jawali, Vivek; Rajeev, Subramanyam

    2010-06-01

    Partial pressure of carbon dioxide and oxygen were transcutaneously measured in adults after off-pump coronary artery bypass (OPCAB) surgery. The clinical use of such measurements and interchangeability with arterial blood gas measurements for weaning patients from postoperative mechanical ventilation were assessed. This was a prospective observational study. Tertiary referral heart hospital. Postoperative OPCAB surgical patients. Transcutaneous oxygen and carbon dioxide measurements. In this prospective observational study, 32 consecutive adult patients in a tertiary care medical center underwent OPCAB surgery. Noninvasive measurement of respiratory gases was performed during the postoperative period and compared with arterial blood gases. The investigator was blinded to the reports of arterial blood gas studies and weaned patients using a "weaning protocol" based on transcutaneous gas measurement. The number of patients successfully weaned based on transcutaneous measurements and the number of times the weaning process was held up were noted. A total of 212 samples (pairs of arterial and transcutaneous values of oxygen and carbon dioxide) were obtained from 32 patients. Bland-Altman plots and mountain plots were used to analyze the interchangeability of the data. Twenty-five (79%) of the patients were weaned from the ventilator based on transcutaneous gas measurements alone. Transcutaneous carbon dioxide measurements were found to be interchangeable with arterial carbon dioxide during 96% of measurements, versus 79% for oxygen measurements. More than three fourths of the patients were weaned from mechanical ventilation and extubated based on transcutaneous gas values alone after OPCAB surgery. The noninvasive transcutaneous carbon dioxide measurement can be used as a surrogate for arterial carbon dioxide measurement to manage postoperative OPCAB patients. Copyright 2010 Elsevier Inc. All rights reserved.

  2. 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

  3. A coincidental variation of the axillary artery: the brachioradial artery and the aberrant posterior humeral circumflex artery passing under the tendon of the latissimus dorsi muscle

    Directory of Open Access Journals (Sweden)

    Marek Konarik

    2014-09-01

    Full Text Available A case of anomalous terminal branching of the axillary artery was encountered and described in a left upper limb of a male cadaver. A series of 214 upper limbs of Caucasian race was dissected. A variant artery, stemming from the very end of the axillary artery followed a superficial course distally. It passed the cubital fossa, ran on the lateral side of the forearm as usual radial artery, crossed ventrally to the palm and terminated in the deep palmar arch. This vessel is a case of the brachioradial artery (incorrectly termed as the “radial artery with high origin”. Moreover, it was associated with another variation, concerning the aberrant posterior humeral circumflex artery passing under the tendon of the latissimus dorsi muscle. The anatomical knowledge of the axillary region is essential for radiodiagnostic, surgical and traumatologic procedures. The superficially located artery brings an elevated danger of heavy bleeding in all unexpected situations, its variant branching can cause problems in radial catheterization procedures and the anomalously coursing other arterial variant poses an elevated danger in surgical procedures concerning the surgical neck of humerus.

  4. Cardiopulmonary effects of anaesthesia maintained by propofol infusion versus isoflurane inhalation in cheetahs (Acinonyx jubatus).

    Science.gov (United States)

    Buck, Roxanne K; Tordiffe, Adrian Sw; Zeiler, Gareth E

    2017-11-01

    To compare the cardiopulmonary effects of propofol total intravenous anaesthesia (TIVA) with isoflurane in cheetahs (Acinonyx jubatus) to evaluate feasibility for field use. Prospective clinical study. A group of 24 adult cheetahs, 12 per group. Cheetahs were immobilized with zolazepam/tiletamine (1.2 mg kg -1 ) and medetomidine [40 μg kg -1 , both intramuscular (IM)] by darting. A maintenance protocol of propofol TIVA (group P) or isoflurane inhalation (group I) was assigned randomly to each cheetah. Anaesthesia was maintained for at least 60 minutes. Cheetahs breathed spontaneously throughout; oxygen was supplemented at 3 L minute -1 . Cardiopulmonary parameters were recorded at 5 minute intervals and three arterial blood gas samples were analysed. Following maintenance, atipamezole was administered IM (200 μg kg -1 ) and recovery was observed. Data are reported as mean±standard deviation; variables over time were compared using a linear mixed model (fixed: time, treatment; random: cheetah). Lack of response to manipulations was maintained in all cases (end-tidal isoflurane percentage 1.1±0.1%, propofol rate maintained at 0.1 mg kg -1  minute -1 ). The heart and respiratory rates were acceptable throughout maintenance. The end-tidal carbon dioxide tension increased slowly [44.0±5.0 mmHg (5.87±0.67 kPa)] with no differences between groups. All cheetahs were initially markedly hypertensive [mean arterial blood pressure (MAP): (163±17 mmHg)]. The MAP normalized for group I (125±30 mmHg) but remained high for group P (161±17 mmHg) (p < 0.001). Arterial carbon dioxide tension [48.9±14.6 mmHg (6.52±1.95 kPa)] never differed between groups. Initial arterial oxygen tension indicated borderline hypoxaemia, but improved with oxygen supplementation. Recovery time was 10.8±5.0 and 51.9±23.5 minutes for group I and group P, respectively. Both protocols provided acceptable cardiopulmonary values. Propofol may be an alternative to isoflurane

  5. A Double Zone Dynamical Model For The Tidal Evolution Of The Obliquity

    Science.gov (United States)

    Damiani, Cilia

    2017-10-01

    It is debated wether close-in giants planets can form in-situ and if not, which mechanisms are responsible for their migration. One of the observable tests for migration theories is the current value of the obliquity. But after the main migration mechanism has ended, the combined effects of tidal dissipation and the magnetic braking of the star lead to the evolution of both the obliquity and the semi-major axis. The observed correlation between effective temperature and measured projected obliquity has been taken as evidence of such mechanisms being at play. Here I present an improved model for the tidal evolution of the obliquity. It includes all the components of the dynamical tide for circular misaligned systems. It uses an analytical formulation for the frequency-averaged dissipation for each mode, depending only on global stellar parameters, giving a measure of the dissipative properties of the convective zone of the host as it evolves in time. The model also includes the effect of magnetic braking in the framework of the double zone model. This results in the estimation of different tidal evolution timescales for the evolution of the planet's semi-major axis and obliquity depending on the properties of the stellar host. This model can be used to test migration theories, provided that a good determination of stellar radii, masses and ages can be obtained.

  6. Coronary Artery Calcium Distribution and Interscan Measurement Variability in End-Stage Renal and Coronary Heart Disease Patients

    International Nuclear Information System (INIS)

    Serafin, Z.; Laskowska, K.; Marzec, M.; Lasek, W.; Sinjab, T.A.; Wlodarczyk, Z.

    2009-01-01

    Background: Coronary heart disease patients and end-stage renal disease patients have been documented to have an increased amount of coronary artery calcifications (CAC). Purpose: To evaluate the distribution of CAC and its influence on interscan variability of measurement in end-stage renal disease and coronary heart disease patients, proven to have calcifications. Material and Methods: 69 patients having CAC, including 34 with coronary heart disease and 35 with end-stage renal disease, were scanned twice with multidetector-row computed tomography (MDCT). Amount of CAC was determined as the number of calcified lesions (CN), total calcium score (CS), calcium volume (CV), and calcium mass (CM). Distribution of CAC was evaluated on a per-patient basis as the median CS and CM of a single lesion. Density of the calcifications was calculated as the patient's CM divided by CV. Results: The overall median CS was 457.2, and the median CM was 75.6 mg. There were no significant differences in the number of calcified lesions, CS, or CM between the two groups. Both CS and CM of a single lesion, as well as the mean calcium density were lower in renal disease patients (P<0.05) than in coronary heart disease subjects. The relative interscan variability of coronary calcium measurement was higher in the renal disease group (P<0.05). There was a negative correlation between the calcium concentration and the relative interscan variability. Conclusion: The results indicate that the coronary calcium distribution influences the measurement interscan reproducibility, and the distribution may differ between end-stage renal disease patients and coronary heart disease patients, reflecting the dissimilar nature of coronary calcifications in those groups

  7. Coronary Artery Calcium Distribution and Interscan Measurement Variability in End-Stage Renal and Coronary Heart Disease Patients

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, Z.; Laskowska, K.; Marzec, M.; Lasek, W. (Dept. of Radiology and Diagnostic Imaging, Nicolaus Copernicus Univ., Collegium Medicum, Bydgoszcz (Poland)); Sinjab, T.A.; Wlodarczyk, Z. (Dept. of Transplantology, Nicolaus Copernicus Univ., Collegium Medicum, Bydgoszcz (Poland))

    2009-04-15

    Background: Coronary heart disease patients and end-stage renal disease patients have been documented to have an increased amount of coronary artery calcifications (CAC). Purpose: To evaluate the distribution of CAC and its influence on interscan variability of measurement in end-stage renal disease and coronary heart disease patients, proven to have calcifications. Material and Methods: 69 patients having CAC, including 34 with coronary heart disease and 35 with end-stage renal disease, were scanned twice with multidetector-row computed tomography (MDCT). Amount of CAC was determined as the number of calcified lesions (CN), total calcium score (CS), calcium volume (CV), and calcium mass (CM). Distribution of CAC was evaluated on a per-patient basis as the median CS and CM of a single lesion. Density of the calcifications was calculated as the patient's CM divided by CV. Results: The overall median CS was 457.2, and the median CM was 75.6 mg. There were no significant differences in the number of calcified lesions, CS, or CM between the two groups. Both CS and CM of a single lesion, as well as the mean calcium density were lower in renal disease patients (P<0.05) than in coronary heart disease subjects. The relative interscan variability of coronary calcium measurement was higher in the renal disease group (P<0.05). There was a negative correlation between the calcium concentration and the relative interscan variability. Conclusion: The results indicate that the coronary calcium distribution influences the measurement interscan reproducibility, and the distribution may differ between end-stage renal disease patients and coronary heart disease patients, reflecting the dissimilar nature of coronary calcifications in those groups.

  8. The common iliac artery in the ground squirrel (Citellus citellus

    Directory of Open Access Journals (Sweden)

    Blagojević M.

    2013-01-01

    Full Text Available The common iliac arteries (a. iliaca communis dextra et a. iliaca communis sinistra are the terminal branches of the abdominal aorta. The paired external iliac artery (a. iliaca externa dextra et a. iliaca externa sinistra is a stronger branch of the paired common iliac artery. Before they leave the abdominal cavity and continue as the femoral arteries (a. femoralis dextra et a. femoralis sinistra each external iliac artery forms the following branches: 1. The internal pudendal artery (a. pudenda interna which, with its branches, supplies the tensor fasciae latae and quadriceps muscles (a. circumflexa femoris lateralis, cranial region of the urinary bladder, cranial end of the uterine horn in females, the deferent duct and tail of the epididymis in males (a. umbilicalis the rectum, the external anal sphincter and perineum (a. rectalis caudalis with blood. 2. The obturator artery (a. obturatoria, which supplies both of the obturator muscles, as well as the proximal end of the adductor muscle. 3. The pudendoepigastric trunk (truncus pudendoepigastricus is a short vessel, which with its branches (a. pudenda externa, a. epigastrica caudalis et a. urethrogenitalis supplies the caudal end of the rectus abdominis muscle, tip of the penis, preputium, superficial inguinal lymph nodes, scrotum in males and inguinal mamma in females, transversus and internus abdominis muscles, neck of the urinary bladder, urethra, vagina and vulva in females and accessory glands in males. 4. Paired internal iliac arteries (a. iliaca interna dextra et a. iliaca interna sinistra are thinner branches than the external iliac arteries. The internal iliac artery with its branches supplies the cranial and caudal parts of the gluteal muscles (a. glutea cranialis et a. glutea caudalis, as well as the muscles of the lateral side of the tail (a. caudalis lateralis. [Projekat Ministarstva nauke Republike Srbije, br. 143018

  9. 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.

  10. Measurement of blood flow in the carotid arteries using color doppler in healthy Korean adults

    International Nuclear Information System (INIS)

    Moon, Ki Ho; Jeon, Do Ig; Choi, Chang Ho; Ro, Young Jin; Kim, Hak Jin; Lee, Suck Hong; Kim, Byung Soo

    1994-01-01

    To evaluate the blood flow patterns and velocities of the carotid arteries in healthy Korean adults. We evaluated the blood flow patterns and measured the peak systolic and end-diastolic velocities of the common, internal and external carotid arteries in 48 healthy adults who did not have cardiovascular disorders and neck lesions. The velocity difference was analyzed according to different age groups. In addition, peak systolic and end-diastolic velocity ratio of the internal to common carotid artery was estimated, and our data were compared with values reported by other authors. Generally, the velocity in the younger age group tends be to higher than in older group. The peak systolic and end diastolic velocities of the internal carotid artery were 84.5 cm/sec and 30.5 cm/sec. The peak systolic and end diastolic velocity ratio of the internal to common carotid artery were 0.715 and 0.966. The internal carotid artery was less resistant in blood flow than the external carotid artery. Our data were lower than the values which were reported by Bluth et al. The blood flow velocities of the internal carotid artery in healthy adults were lower than those of previous reported foreign values, but the patterns were similar

  11. Constraining the cause of the end-Guadalupian extinction with coupled records of carbon and calcium isotopes

    Science.gov (United States)

    Jost, A. B.; Mundil, R.; He, B.; Brown, S. T.; Altiner, D.; Sun, Y.; DePaolo, D. J.; Payne, J.

    2013-12-01

    A negative δ13C excursion in carbonate sediments from Guadalupian (Middle Permian) and Lopingian (Late Permian) stratigraphic sections has been interpreted to result from a large carbon cycle disturbance during end-Guadalupian extinction event (ca. 260 Ma). However, the carbon isotope data alone are insufficient to uniquely determine the type and magnitude of perturbations to the global carbon cycle. The carbon and calcium cycles are coupled via CaCO3 burial, so changes in calcium isotopes can be used to constrain the cause of a carbon isotope excursion. In this study, we present coupled carbon and calcium isotope records from three Guadalupian-Lopingian (G/L) sections in China and Turkey. Isotope records among our studied sections are inconsistent in both their δ13C and δ44/40Ca records. Similar inconsistencies in δ13C among sections occur across previously published datasets. Sections with large (>3‰) changes in δ13C either show evidence for diagenetic alteration or do not show δ13C and δ44/40Ca changes consistent with severe volcanic degassing from Emeishan or methane clathrate destabilization. We conclude that the large isotopic changes are more likely the result of local burial conditions or diagenetic effects, rather than a large carbon cycle disturbance. Perturbations to the global carbon and calcium cycles appear to have been much smaller across the G/L transition than across the subsequent Permian-Triassic boundary. This finding is consistent with recent paleobiological data showing that the end-Guadalupian extinction was much less severe than previously believed, and was indistinguishable in magnitude from background intervals. However, selective extinction of marine animals with passive respiratory physiology indicates that the G/L extinction cannot simply be due to background extinction or sampling failure, and that it was triggered by some environmental event. Therefore, any environmental event must have been small enough to not generate large

  12. 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)

  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. 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.

  15. Source and dispersal of suspended sediment in the macro-tidal Gulf of Kachchh

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Nath, B.N.; Vethamony, P.; Ilangovan, D.

    and transport of carbon, minerals and pollutants to the oceans (Eisma, 1981; McKee, 2003). Macro-tidal areas are usually associated with high SSC because of higher energy conditions with sediments getting resuspended and transported depending on the harmonics... International 104, 69–86. Chandrasekharam, D., Mahoney, J.J., Sheth, H.C., Duncan, R.A., 1999. Elemental and Nd–Sr–Pb isotope geochemistry of flows and dikes from the Tapi rift, Deccan flood basalt province. India Journal of Volcanology and Geothermal Research...

  16. Arterial supply of the intestines of New Zealand rabbits (Oryctolagus cuniculus

    Directory of Open Access Journals (Sweden)

    Leandro Marcel Fernandes Cortellini

    2008-03-01

    Full Text Available The origin and ramification patterns of the intestinal arteries of rabbits were studied. The vessels were injected with a latex solution before dissection in 20 adult specimens. The cranial mesenteric artery originates from the abdominal aorta and gives off the following arteries: pancreatic branches; caudal pancreaticoduodenal; colic medium; jejunal (with variable number, ileocolic arteries, the colic branches, and ileal branches. The caudal mesenteric artery originates next to the end of the abdominal aorta and off a left colic artery that gives origin to the sigmoidal arteries and a cranial rectal artery.

  17. Low pulmonary artery flush perfusion pressure combined with high positive end-expiratory pressure reduces oedema formation in isolated porcine lungs

    International Nuclear Information System (INIS)

    Schumann, Stefan; Schließmann, Stephan J; Wagner, Giskard; Goebel, Ulrich; Priebe, Hans-Joachim; Guttmann, Josef; Kirschbaum, Andreas

    2010-01-01

    Flush perfusion of the pulmonary artery with organ protection solution is a standard procedure before lung explantation. However, rapid flush perfusion may cause pulmonary oedema which is deleterious in the lung transplantation setting. In this study we tested the hypotheses that high pulmonary perfusion pressure contributes to the development of pulmonary oedema and positive end-expiratory pressure (PEEP) counteracts oedema formation. We expected oedema formation to increase weight and decrease compliance of the lungs on the basis of a decrease in alveolar volume as fluid replaces alveolar air spaces. The pulmonary artery of 28 isolated porcine lungs was perfused with a low-potassium dextrane solution at low (mean 27 mmHg) or high (mean 40 mmHg) pulmonary artery pressure (PAP) during mechanical ventilation at low (4 cmH 2 O) or high (8 cmH 2 O) PEEP, respectively. Following perfusion and storage, relative increases in lung weight were smaller (p < 0.05) during perfusion at low PAP (62 ± 32% and 42 ± 26%, respectively) compared to perfusion at high PAP (133 ± 54% and 87 ± 30%, respectively). Compared to all other PAP–PEEP combinations, increases in lung weight were smallest (44 ± 9% and 27 ± 12%, respectively), nonlinear intratidal lung compliance was largest (46% and 17% respectively, both p < 0.05) and lung histology showed least infiltration of mononuclear cells in the alveolar septa, and least alveolar destruction during the combination of low perfusion pressure and high PEEP. The findings suggest that oedema formation during pulmonary artery flush perfusion in isolated and ventilated lungs can be reduced by choosing low perfusion pressure and high PEEP. PAP–PEEP titration to minimize pulmonary oedema should be based on lung mechanics and PAP monitoring

  18. 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.

  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. On-Pump Versus Off-Pump Coronary Artery Bypass Surgery in Elderly Patients

    DEFF Research Database (Denmark)

    Houlind, Kim; Kjeldsen, Bo Juul; Madsen, Susanne Nørgaard

    2012-01-01

    BACKGROUND: Conventional coronary artery bypass grafting performed with the use of cardiopulmonary bypass is a well-validated treatment for patients with ischemic heart disease. Off-pump coronary artery bypass grafting (OPCAB) has been suggested to reduce the number of perioperative complications......, especially in elderly patients. METHODS AND RESULTS: In a multicenter, randomized trial, we assigned 900 patients >70 years of age to conventional coronary artery bypass grafting or OPCAB surgery. After 30 days, a blinded end-point committee assessed whether a combined end point of death, stroke...... experiencing the combined end point within 30 days was 10.2% for conventional coronary artery bypass grafting and 10.7% for OPCAB. Implied risk difference of 0.4% (with a 95% confidence interval, -3.6 to 4.4) showed nonsignificance in a standard test for equality (P=0.83) and for noninferiority...

  1. 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.

  2. Short-term effects of tidal flooding on soil nitrogen mineralization in a Chinese tidal salt marsh

    Science.gov (United States)

    Gao, Haifeng; Bai, Junhong; Deng, Xiaoya; Lu, Qiongqiong; Ye, Xiaofei

    2018-02-01

    Tidal flooding is an important control of nitrogen biogeochemistry in wetland ecosystems of Yellow River Delta, China. Variations in hydrology could change soil redox dynamics and conditions for microorganisms living. A tidal simulation experiment was designed to extract tidal flooding effect on nitrogen mineralization of salt marsh soil. Inorganic nitrogen and relevant enzyme were measured during the 20-day incubation period. Considering the variation of both inorganic N and enzymes, nitrogen mineralization process in tidal salt marsh could be divided into 2 phases of short term response and longtime adaption by around 12th incubation day as the inflection point. Soil ammonium nitrogen (NH4+-N) and volatilized ammonia (NH3) occupied the mineralization process since nitrate nitrogen (NO3--N) was not detected over whole incubation period. NH4+-N varied fluctuant and increased significantly after 12 day's incubation. Released NH3 reached to peak value of 14.24 mg m-2 d-1 at the inflection point and declined thereafter. Inorganic nitrogen released according to net nitrogen mineralization rate (RM) under the tidal flooding condition without plant uptake except first 2 days. However, during the transitional period of 6-12 days, RM decreased notably to almost 0 and increased again after inflection point with the value of 0.182 mg kg-1 d-1. It might be due to the change of microbial composition and function when soil shifted from oxic to anoxic, which were reflected by arylamidase, urease and fluorescein diacetate. Fluorescein diacetate hydrolysis and arylamidase had the similar variation of U style with decreasing activities before 12 days' incubation. All the enzymes measured in this experiment increased after inflection point. Whereas, urease activity kept constant from 2 to 12 days. Alternant oxidation reduction condition would increase N loss through denitrification and ammonia volatilization during the transitional period, while more inorganic nitrogen would be

  3. 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.

  4. 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.

  5. 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.

  6. 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...

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

    Science.gov (United States)

    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.

  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. 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.

  10. 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 ...

  11. The Predictive Value of Integrated Pulmonary Index after Off-Pump Coronary Artery Bypass Grafting: A Prospective Observational Study

    Directory of Open Access Journals (Sweden)

    Evgenia V. Fot

    2017-08-01

    Full Text Available BackgroundThe early warning scores may increase the safety of perioperative period. The objective of this study was to assess the diagnostic and predictive role of Integrated Pulmonary Index (IPI after off-pump coronary artery bypass grafting (OPCAB.Materials and MethodsForty adult patients undergoing elective OPCAB were enrolled into a single-center prospective observational study. We assessed respiratory function using IPI that includes oxygen saturation, end-tidal CO2, respiratory rate, and pulse rate. In addition, we evaluated blood gas analyses and hemodynamics, including ECG, invasive arterial pressure, and cardiac index. The measurements were performed after transfer to the intensive care unit, after spontaneous breathing trial and at 2, 6, 12, and 18 h after extubation.Results and DiscussionThe value of IPI registered during respiratory support correlated weakly with cardiac index (rho = 0.4; p = 0.04 and ScvO2 (rho = 0.4, p = 0.02. After extubation, IPI values decreased significantly, achieving a minimum by 18 h. The IPI value ≤9 at 6 h after extubation was a predictor of complicated early postoperative period (AUC = 0.71; p = 0.04 observed in 13 patients.ConclusionIn off-pump coronary surgery, the IPI decreases significantly after tracheal extubation and may predict postoperative complications.

  12. 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...

  13. Ultralow field emission from thinned, open-ended, and defected carbon nanotubes by using microwave hydrogen plasma processing

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Jian-Hua, E-mail: jhdeng1983@163.com [College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Cheng, Lin; Wang, Fan-Jie; Yu, Bin; Li, Guo-Zheng; Li, De-Jun [College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387 (China); Cheng, Guo-An [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China)

    2015-01-01

    Graphical abstract: Thinned, open-ended, and defected carbon nanotubes were prepared by using hydrogen plasma processing. The processed carbon nanotubes have far better field emission performance than that of the pristine ones. - Highlights: • CVD prepared CNT arrays were processed by microwave hydrogen plasma. • Thinned, open-ended, and defected CNTs were obtained. • Processed CNTs have far better field emission performance than the pristine ones. • Processed CNTs have applicable emission stability after being perfectly aged. - Abstract: Ultralow field emission is achieved from carbon nanotubes (CNTs) by using microwave hydrogen plasma processing. After the processing, typical capped CNT tips are removed, with thinned, open-ended, and defected CNTs left. Structural analyses indicate that the processed CNTs have more SP{sup 3}-hybridized defects as compared to the pristine ones. The morphology of CNTs can be readily controlled by adjusting microwave powers, which change the shape of CNTs by means of hydrogen plasma etching. Processed CNTs with optimal morphology are found to have an ultralow turn-on field of 0.566 V/μm and threshold field of 0.896 V/μm, much better than 0.948 and 1.559 V/μm of the as-grown CNTs, respectively. This improved FE performance is ascribed to the structural changes of CNTs after the processing. The thinned and open-ended shape of CNTs can facilitate electron tunneling through barriers and additionally, the increased defects at tube walls can serve as new active emission sites. Furthermore, our plasma processed CNTs exhibit excellent field emission stability at a large emission current density of 10.36 mA/cm{sup 2} after being perfectly aged, showing promising prospects in applications as high-performance vacuum electron sources.

  14. Simulating the Effects of Sea Level Rise on the Resilience and Migration of Tidal Wetlands along the Hudson River.

    Directory of Open Access Journals (Sweden)

    Nava M Tabak

    Full Text Available Sea Level Rise (SLR caused by climate change is impacting coastal wetlands around the globe. Due to their distinctive biophysical characteristics and unique plant communities, freshwater tidal wetlands are expected to exhibit a different response to SLR as compared with the better studied salt marshes. In this study we employed the Sea Level Affecting Marshes Model (SLAMM, which simulates regional- or local-scale changes in tidal wetland habitats in response to SLR, and adapted it for application in a freshwater-dominated tidal river system, the Hudson River Estuary. Using regionally-specific estimated ranges of SLR and accretion rates, we produced simulations for a spectrum of possible future wetland distributions and quantified the projected wetland resilience, migration or loss in the HRE through the end of the 21st century. Projections of total wetland extent and migration were more strongly determined by the rate of SLR than the rate of accretion. Surprisingly, an increase in net tidal wetland area was projected under all scenarios, with newly-formed tidal wetlands expected to comprise at least 33% of the HRE's wetland area by year 2100. Model simulations with high rates of SLR and/or low rates of accretion resulted in broad shifts in wetland composition with widespread conversion of high marsh habitat to low marsh, tidal flat or permanent inundation. Wetland expansion and resilience were not equally distributed through the estuary, with just three of 48 primary wetland areas encompassing >50% of projected new wetland by the year 2100. Our results open an avenue for improving predictive models of the response of freshwater tidal wetlands to sea level rise, and broadly inform the planning of conservation measures of this critical resource in the Hudson River Estuary.

  15. Earthquake potential revealed by tidal influence on earthquake size-frequency statistics

    Science.gov (United States)

    Ide, Satoshi; Yabe, Suguru; Tanaka, Yoshiyuki

    2016-11-01

    The possibility that tidal stress can trigger earthquakes is long debated. In particular, a clear causal relationship between small earthquakes and the phase of tidal stress is elusive. However, tectonic tremors deep within subduction zones are highly sensitive to tidal stress levels, with tremor rate increasing at an exponential rate with rising tidal stress. Thus, slow deformation and the possibility of earthquakes at subduction plate boundaries may be enhanced during periods of large tidal stress. Here we calculate the tidal stress history, and specifically the amplitude of tidal stress, on a fault plane in the two weeks before large earthquakes globally, based on data from the global, Japanese, and Californian earthquake catalogues. We find that very large earthquakes, including the 2004 Sumatran, 2010 Maule earthquake in Chile and the 2011 Tohoku-Oki earthquake in Japan, tend to occur near the time of maximum tidal stress amplitude. This tendency is not obvious for small earthquakes. However, we also find that the fraction of large earthquakes increases (the b-value of the Gutenberg-Richter relation decreases) as the amplitude of tidal shear stress increases. The relationship is also reasonable, considering the well-known relationship between stress and the b-value. This suggests that the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal stress levels. We conclude that large earthquakes are more probable during periods of high tidal stress.

  16. 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

  17. End of the "Little Ice Age" in the Alps not forced by industrial black carbon

    Science.gov (United States)

    Sigl, Michael; Osmont, Dimtri; Gabrieli, Jacopo; Barbante, Carlo; Schwikowski, Margit

    2016-04-01

    Light absorbing aerosols present in the atmosphere and cryosphere play an important role in the climate system. Their presence in ambient air and snow changes radiative properties of these media, thus contributing to increased atmospheric warming and snowmelt. High spatio-temporal variability of aerosol concentrations in these media and a shortage of long-term observations contribute to large uncertainties in properly assigning the climate effects of these aerosols through time. Glaciers in the European Alps began to retreat abruptly from their mid-19th century maximum, marking what appeared to be the end of the Little Ice Age. Radiative forcing by increasing deposition of industrial black carbon to snow has been suggested as the main driver of the abrupt glacier retreats in the Alps (Painter et al. 2012). Basis for this hypothesis were model simulations using ice-core measurements of elemental carbon at low temporal resolution from two ice cores in the Alps. Here we present sub-annually resolved, well replicated ice-core measurements of refractory black carbon (rBC; using a SP2 soot photometer), mineral dust (Fe, Ca), biomass burning (NH4, K) and distinctive industrial pollution tracers (Bi, Pb, SO4) from an ice core in the Alps covering the past 250 years. These reconstructions allow to precisely compare the timing of observed acceleration of glacier melt in the mid-19th century with that of the increase of soot deposition on ice-sheets caused by the industrialization of Western Europe. Our study suggests that at the time when European rBC emission rates started to significantly increase Alpine glaciers have already experienced more than 70% of their total 19th century length reduction. Industrial BC emissions can therefore not been considered as the primary forcing of the rapid deglaciation at the end of the Little Ice Age in the Alps. References: Painter, T. H., M. G. Flanner, G. Kaser, B. Marzeion, R. A. VanCuren, and W. Abdalati (2013), End of the Little Ice

  18. 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

  19. Tidal Stream Generators, current state and potential opportunities for condition monitoring

    DEFF Research Database (Denmark)

    Kappatos, Vassilios; Georgoulas, George; Avdelidis, Nicolas

    2016-01-01

    Tidal power industry has made significant progress towards commercialization over the past decade. Significant investments from sector leaders, strong technical progress and positive media coverage have established the credibility of this specific renewable energy source. However, its progress...... is being retarded by operation and maintenance problems, which results in very low operational availability times, as low as 25 %. This paper presents a literature review of the current state of tidal device operators as well as some commercial tidal turbine condition monitoring solutions. Furthermore......, an overview is given of the global tidal activity status (tidal energy market size and geography), the key industry activity and the regulations-standards related with tidal energy industry. Therefore, the main goal of this paper is to provide a bird’s view of the current status of the tidal power industry...

  20. Complications of operative treatment of injuries of peripheral arteries.

    Science.gov (United States)

    Velinovic, M M; Davidovic, B L; Lotina, I S; Vranes, R M; Djukic, L P; Arsov, J V; Ristic, V M; Kocica, J M; Petrovic, L P

    2000-06-01

    In 1991 and 1992, a total of 97 patients with 106 peripherial arterial injuries underwent surgery at the Institute for Cardiovascular Diseases, Clinical Centre of Serbia. Civilian injuries accounted for 53 (54.6%) patients (94.3% males, age range: 16-63 yr, mean: 35.2), and 44 patients had war injuries (93.2% males, age range: 19-61 yr, mean: 34.8). The injuries affected the superfitial femoral artery in 31 (29.24%); the popliteal artery in 28 (26.41%); the brachial artery in 17 (16.04%); the posterior tibial artery in 6 (5.66%); the axillary artery in 5 (4.72%); the anterior tibial artery in 5 (4.72%); the tibioperoneal trunk in 4 (3. 77%); the common femoral artery in 4 (3.77%); the external iliac artery in 2 (1.89%); the profound femoral artery in 2 (1.89%); the radial artery in 1 (0.94%); and ulnar artery in 1 (0.94%).A total of 98 reconstructive procedures were used to treat these patients. Graft interposition carried out in 50 (51.02%); by pass in 25 (25. 51%); end-to-end anastomosis in 9 (9.18%); suture in 8 (8.16%); ligation in 4 (4.08%); and patch-angioplasty in 2 (2.04%). Primary reconstruction of injured arteries was performed in 72.2% and secondary repair in 27.8% cases. Infection developed in 51 (52.57%) patients, and it was significantly (P<0.05) more common in the war injuries (70.45%) and in secondary repairs (88.89%). The presence of associated lesions (69.56%) was also correlated with a greater rate of infection. Amputation was necessary in 21 (21.65%) of our patients, and was significantly (P<0.05) more often performed after secondary (44.44%) than primary operations (12.86%) and in the presence of associated injuries (32.61%).

  1. 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)

  2. Restoration of Tidal Flow to Impounded Salt Marsh Exerts Mixed Effect on Leaf Litter Decomposition

    Science.gov (United States)

    Henry, B. A.; Schade, J. D.; Foreman, K.

    2015-12-01

    Salt marsh impoundments (e.g. roads, levees) disconnect marshes from ocean tides, which impairs ecosystem services and often promotes invasive species. Numerous restoration projects now focus on removing impoundments. Leaf litter decomposition is a central process in salt marsh carbon and nutrient cycles, and this study investigated the extent to which marsh restoration alters litter decomposition rates. We considered three environmental factors that can potentially change during restoration: salinity, tidal regime, and dominant plant species. A one-month field experiment (Cape Cod, MA) measured decay of litter bags in impounded, restored, and natural marshes under ambient conditions. A two-week lab experiment measured litter decay in controlled incubations under experimental treatments for salinity (1ppt and 30 ppt), tidal regime (inundated and 12 hr wet-dry cycles), and plant species (native Spartina alterniflora and invasive Phragmites australis). S. alterniflora decomposed faster in situ than P. australis (14±1.0% mass loss versus 0.74±0.69%). Corroborating this difference in decomposition, S. alterniflora supported greater microbial respiration during lab incubation, measured as CO2 flux from leaf litter and biological oxygen demand of water containing leached organic matter (OM). However, nutrient analysis of plant tissue and leached OM show P. australis released more nitrogen than S. alterniflora. Low salinity treatments in both lab and field experiments decayed more rapidly than high salinity treatments, suggesting that salinity inhibited microbial activity. Manipulation of inundation regime did not affect decomposition. These findings suggest the reintroduction of tidal flow to an impounded salt marsh can have mixed effects; recolonization by the native cordgrass could supply labile OM to sediment and slow carbon sequestration, while an increase in salinity might inhibit decomposition and accelerate sequestration.

  3. 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

  4. 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.

  5. 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

  6. On the Formation of Ultra-Difuse Galaxies as Tidally-Stripped Systems

    Science.gov (United States)

    Carleton, Timothy; Cooper, Michael; Kaplinghat, Manoj; Errani, Raphael; Penarrubia, Jorge

    2018-01-01

    The recent identification of a large population of so-called 'Ultra-Diffuse' Galaxies (UDGs), with stellar masses ~108 M⊙, but half light radii over 1.5 kpc, has challenged our understanding of galaxy evolution. Motivated by the environmental dependence of UDG properties and abundance, I present a model for the formation of UDGs through tidal-stripping of dwarf galaxies in cored dark matter halos. To test this scenario, I utilize results from simulations of tidal stripping, which demonstrate that changes in the stellar profile of a tidally stripped galaxy can be written as a function of the amount of tidal stripping experienced by the halo (tidal tracks). These tracks, however, are different for cored and cuspy halos. Additional simulations show how the halo responds to tidal interactions given the halo orbit within a cluster.In particular, dwarf elliptical galaxies, born in 1010-10.5 M⊙ halos, expand significantly as a result of tidal stripping and produce UDGs. Applying these models to the population of halos in the Bolshoi simulation, I am able to follow the effects of tidal stripping on the dwarf galaxy population in clusters. Using tidal tracks for cuspy halos does not reproduce the observed properties of UDGs. However, using the tidal tracks for cored halos, I reproduce the distribution of sizes, stellar masses, and abundance of UDGs in clusters remarkably well.

  7. Tidal interaction and coalescence of close binary white dwarfs

    International Nuclear Information System (INIS)

    Webbink, R.F.; Iben, I. Jr.

    1987-01-01

    The physical processes which govern the interaction and final coalescence of close binary white dwarfs are examined. During the approach to mass transfer, the rate of accumulation of rotational energy by a white dwarf can exceed 10 to the 37th erg/s, raising the possibility that the initial phases of mass transfer are strongly influenced by tidal heating of the donor star. The potential energy released by accretion is incapable of removing more than a minor fraction of this material from the system, and numerical simulations show that the accreted envelope engulfs the donor star, leading to formation of common envelope binary before carbon can be ignited at the base of the accreted envelope. Unless shocks can lift the degeneracy of the donor core, a core mass exceeding the Chandrasekhar limit can be created, leading directly to core collapse and a supernova explosion, regardless of whether or not carbon is ignited in the nondegenerate envelope. It is plausible that most of the mass of the donor white dwarf is assimilated in a degenerate state by the accretor. 32 references

  8. 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.)

  9. 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

  10. Hydraulic effects on nitrogen removal in a tidal spring-fed river

    Science.gov (United States)

    Hensley, Robert T.; Cohen, Matthew J.; Korhnak, Larry V.

    2015-03-01

    Hydraulic properties such as stage and residence time are important controls on riverine N removal. In most rivers, these hydraulic properties vary with stochastic precipitation forcing, but in tidal rivers, hydraulics variation occurs on a predictable cycle. In Manatee Springs, a highly productive, tidally influenced spring-fed river in Florida, we observed significant reach-scale N removal that varied in response to tidally driven variation in hydraulic properties as well as sunlight-driven variation in assimilatory uptake. After accounting for channel residence time and stage variation, we partitioned the total removal signal into assimilatory (i.e., plant uptake) and dissimilatory (principally denitrification) pathways. Assimilatory uptake was strongly correlated with primary production and ecosystem C:N was concordant with tissue stoichiometry of the dominant autotrophs. The magnitude of N removal was broadly consistent in magnitude with predictions from models (SPARROW and RivR-N). However, contrary to model predictions, the highest removal occurred at the lowest values of τ/d (residence time divided by depth), which occurred at low tide. Removal efficiency also exhibited significant counterclockwise hysteresis with incoming versus outgoing tides. This behavior is best explained by the sequential filling and draining of transient storage zones such that water that has spent the longest time in the storage zone, and thus had the most time for N removal, drains back into the channel at the end of an outgoing tide, concurrent with shortest channel residence times. Capturing this inversion of the expected relationship between channel residence time and N removal highlights the need for nonsteady state reactive transport models.

  11. The TRAPPIST-1 system: orbital evolution, tidal dissipation, formation and habitability

    Science.gov (United States)

    Papaloizou, J. C. B.; Szuszkiewicz, Ewa; Terquem, Caroline

    2018-06-01

    We study the dynamical evolution of the TRAPPIST-1 system under the influence of orbital circularization through tidal interaction with the central star. We find that systems with parameters close to the observed one evolve into a state where consecutive planets are linked by first-order resonances and consecutive triples, apart from planets c, d and e, by connected three-body Laplace resonances. The system expands with period ratios increasing and mean eccentricities decreasing with time. This evolution is largely driven by tides acting on the innermost planets, which then influence the outer ones. In order that deviations from commensurability become significant only on Gyr time-scales or longer, we require that the tidal parameter associated with the planets has to be such that Q΄ > ˜102 - 3. At the same time, if we start with two subsystems, with the inner three planets comprising the inner one, Q΄ associated with the planets has to be on the order (and not significantly exceeding) 102 - 3 for the two subsystems to interact and end up in the observed configuration. This scenario is also supported by modelling of the evolution through disc migration which indicates that the whole system cannot have migrated inwards together. Also, in order to avoid large departures from commensurabilities, the system cannot have stalled at a disc inner edge for significant time periods. We discuss the habitability consequences of the tidal dissipation implied by our modelling, concluding that planets d, e and f are potentially in habitable zones.

  12. The dynamical fate of self-gravitating disc fragments after tidal downsizing

    Science.gov (United States)

    Forgan, Duncan; Parker, Richard J.; Rice, Ken

    2015-02-01

    The gravitational instability model of planet/brown dwarf formation proposes that protostellar discs can fragment into objects with masses above a few Jupiter masses at large semimajor axis. Tidal downsizing may reduce both the object mass and semimajor axis. However, most studies of tidal downsizing end when the protostellar disc disperses, while the system is embedded in its parent star-forming region. To compare disc fragment descendants with exoplanet and brown dwarf observations, the subsequent dynamical evolution must be explored. We carry out N-body integrations of fragment-fragment scattering in multi-object star systems, and star systems embedded in substructured clusters. In both cases, we use initial conditions generated by population synthesis models of tidal downsizing. The scattering simulations produce a wide range of eccentricities. The ejection rate is around 25 per cent. The ejecta mass distribution is similar to that for all objects, with a velocity dispersion consistent with those produced by full hydrodynamic simulations. The semimajor axis distribution after scattering extends to parsec scales. In the cluster simulations, 13 per cent of the objects are ejected from their planetary system, and around 10 per cent experience significant orbit modification. A small number of objects are recaptured on high-eccentricity, high-inclination orbits. The velocity distribution of ejecta is similar to that produced by fragment-fragment scattering. If fragment-fragment scattering and cluster stripping act together, then disc fragmentation should be efficient at producing free-floating substellar objects, and hence characterizing the free-floating planet population will provide strong constraints on the frequency of disc fragmentation.

  13. Effects of thermal discomfort in an office on perceived air quality, SBS symptoms, physiological responses and human performance

    DEFF Research Database (Denmark)

    Lan, Li; Wargocki, Pawel; Wyon, David Peter

    2011-01-01

    The effects of thermal discomfort on health and human performance were investigated in an office, in an attempt to elucidate the physiological mechanisms involved. Twelve subjects (six men and six women) performed neurobehavioral tests and tasks typical of office work while thermally neutral (at 22......, and were less willing to exert effort. Task performance decreased when the subjects felt warm. Their heart rate, respiratory ventilation, and end-tidal partial pressure of carbon dioxide increased significantly, and their arterial oxygen saturation decreased. Tear film quality was found to be significantly...... reduced at the higher temperature when they felt warm. No effects were observed on salivary biomarkers (alpha-amylase and cortisol). The present results imply that the negative effects on health and performance that occur when people feel thermally warm at raised temperatures are caused by physiological...

  14. 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

  15. 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)

  16. 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...

  17. Noninvasive prediction of left ventricular end-diastolic pressure in patients with coronary artery disease and preserved ejection fraction.

    Science.gov (United States)

    Abd-El-Aziz, Tarek A

    2012-01-01

    The aim of this study was to compare 3 different available methods for estimating left ventricular end-diastolic pressure (LVEDP) noninvasively in patients with coronary artery disease and preserved left ventricular ejection fraction (EF). We used 3 equations for noninvasive estimation of LVEDP: The equation of Mulvagh et al., LVEDP(1) = 46 - 0.22 (IVRT) - 0.10 (AFF) - 0.03 (DT) - (2 ÷ E/A) + 0.05 MAR; the equation of Stork et al., LVEDP(2) = 1.06 + 15.15 × Ai/Ei; and the equation of Abd-El-Aziz, LVEDP(3) = [0.54 (MABP) × (1 - EF)] - 2.23. ( A, A-wave velocity; AFF, atrial filling fraction; Ai, time velocity integral of A wave; DT, deceleration time; E, E-wave velocity; Ei, time velocity integral of E wave; IVRT, isovolumic relaxation time; MABP, mean arterial blood pressure; MAR, time from termination of mitral flow to the electrocardiographic R wave; Ti, time velocity integral of total wave.) LVEDP measured by catheterization was correlated with LVEDP(1) (r = 0.52, P Aziz, LVEDP = [0.54 MABP × (1 - EF)] - 2.23, appears to be the most accurate, reliable, and easily applied method for estimating LVEDP noninvasively in patients with preserved left ventricular ejection fraction and an LVEDP < 20 mm Hg. Copyright © 2012 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  18. Nutritional composition of suspended particulate matter in a tropical mangrove creek during a tidal cycle (Can Gio, Vietnam)

    Science.gov (United States)

    David, Frank; Marchand, Cyril; Taillardat, Pierre; Thành-Nho, Nguyễn; Meziane, Tarik

    2018-01-01

    Mangrove forests are highly productive ecosystems and mangrove-derived organic matter has generally been assumed to play a basal role in sustaining coastal food webs. However, the mechanisms of mangrove-derived organic matter utilisation by consumers are not fully understood. In this study, we were interested in hourly changes in the nutritional quality of suspended particulate matter (SPM) entering and departing a mangrove creek during a tidal cycle. We determined the fatty acid composition and δ13C stable isotope signature of SPM during a 26 h tidal cycle in a creek of the Can Gio Mangrove Biosphere Reserve (Southern Vietnam). Regarding fatty acids, the nutritional quality of SPM was low during most of the tidal cycle. However, it greatly increased during the first part of the strongest flood tide, occurring during daytime. The pulse of highly nutritive organic matter brought to the ecosystem was mostly composed of algal cells growing in specific shallow zones of the mangrove, that use nutrients and CO2 exported during the preceding ebb tide and originating from the mineralisation of mangrove-derived organic matter, as evidenced by their δ13C signatures. This study confirms that mangrove-derived carbon plays a basal role in sustaining trophic webs of mangrove tidal creeks, but that its nutritive value is greatly enhanced when a first step of mineralisation is achieved and CO2 is photosynthesised by algal cells.

  19. 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.

  20. 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.

  1. The Integration of Environmental Constraints into Tidal Array Optimisation

    Science.gov (United States)

    du Feu, Roan; de Trafford, Sebastian; Culley, Dave; Hill, Jon; Funke, Simon W.; Kramer, Stephan C.; Piggott, Matthew D.

    2015-04-01

    It has been estimated by The Carbon Trust that the marine renewable energy sector, of which tidal stream turbines are projected to play a large part, could produce 20% of the UK's present electricity requirements. This has lead to the important question of how this technology can be deployed in an economically and environmentally friendly manner. Work is currently under way to understand how the tidal turbines that constitute an array can be arranged to maximise the total power generated by that array. The work presented here continues this through the inclusion of environmental constraints. The benefits of the renewable energy sector to our environment at large are not in question. However, the question remains as to the effects this burgeoning sector will have on local environments, and how to mitigate these effects if they are detrimental. For example, the presence of tidal arrays can, through altering current velocity, drastically change the sediment transport into and out of an area along with re-suspending existing sediment. This can have the effects of scouring or submerging habitat, mobilising contaminants within the existing sediment, reducing food supply and altering the turbidity of the water. All of which greatly impact upon any fauna in the affected region. This work pays particular attention to the destruction of habitat of benthic fauna, as this is quantifiable as a direct result of change in the current speed; a primary factor in determining sediment accumulation on the sea floor. OpenTidalFarm is an open source tool that maximises the power generated by an array through repositioning the turbines within it. It currently uses a 2D shallow water model with turbines represented as bump functions of increased friction. The functional of interest, power extracted by the array, is evaluated from the flow field which is calculated at each iteration using a finite element method. A gradient-based local optimisation is then used through solving the

  2. [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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. New Concept for Assessment of Tidal Current Energy in Jiangsu Coast, China

    Directory of Open Access Journals (Sweden)

    Ji-Sheng Zhang

    2013-01-01

    Full Text Available Tidal current energy has attracted more and more attentions of coastal engineers in recent years, mainly due to its advantages of low environmental impact, long-term predictability, and large energy potential. In this study, a two-dimensional hydrodynamic model is applied to predict the distribution of mean density of tidal current energy and to determine a suitable site for energy exploitation in Jiangsu Coast. The simulation results including water elevation and tidal current (speed and direction were validated with measured data, showing a reasonable agreement. Then, the model was used to evaluate the distribution of mean density of tidal current energy during springtide and neap tide in Jiangsu Coast. Considering the discontinuous performance of tidal current turbine, a new concept for assessing tidal current energy is introduced with three parameters: total operating time, dispersion of operating time, and mean operating time of tidal current turbine. The operating efficiency of tidal current turbine at three locations around radial submarine sand ridges was taken as examples for comparison, determining suitable sites for development of tidal current farm.

  8. Seasonal dynamics of dissolved, particulate and microbial components of a tidal saltmarsh-dominated estuary under contrasting levels of freshwater discharge

    Science.gov (United States)

    Bittar, Thais B.; Berger, Stella A.; Birsa, Laura M.; Walters, Tina L.; Thompson, Megan E.; Spencer, Robert G. M.; Mann, Elizabeth L.; Stubbins, Aron; Frischer, Marc E.; Brandes, Jay A.

    2016-12-01

    Tidal Spartina-dominated saltmarshes and estuaries on the Southeast US coast are global hotspots of productivity. In coastal Georgia, tidal amplitudes and saltmarsh productivity are the highest along the Southeast US coast. Coastal Georgia is characterized by a humid subtropical seasonal climate, and inter-annual variability in precipitation, and freshwater discharge. The 2012-2013 timeframe encompassed contrasting levels of discharge for the Savannah River, a major Georgia river, with a 4.3-fold greater discharge in summer 2013 relative to summer 2012. In situ measurements of temperature, salinity, precipitation and Secchi depth, and water samples were collected weekly at high tide throughout 2012 and 2013 from the Skidaway River Estuary, a tidal saltmarsh-dominated estuary in coastal Georgia influenced by Savannah River hydrology. The effects of elevated discharge on the seasonal trends of water column components were evaluated. The shift from low discharge (2012) to high discharge (2013) led to decreased salinity in summer 2013, but no significant increases in inorganic nutrient (NH4, NOx, SiO2 and PO4) concentrations. Dissolved inorganic carbon (DIC) concentrations decreased, and DIC stable isotopic signatures (δ13C-DIC values) were depleted in summer 2013 relative to summer 2012. In 2013 dissolved organic carbon (DOC) concentrations, chromophoric and fluorescent dissolved organic matter (DOM: CDOM, FDOM) intensities, specific UV-absorbance (SUVA254) and relative humic-like fluorescence were all higher than in 2012, indicating that, as discharge increased in 2013, estuarine water became enriched in terrigenous DOM. Secchi depth and particulate organic carbon (POC) and nitrogen (PON) concentrations displayed clear seasonal patterns that were not significantly altered by discharge. However, δ13C-POC and δ15N-PON isotopic signatures indicated higher terrigenous contributions at elevated discharge. Discharge influenced cyanobacterial composition, but did not

  9. CT arterial portography and CT arteriography with a triple-lumen balloon catheter

    International Nuclear Information System (INIS)

    Murakami, T.; Oi, H.; Hori, M.; Kim, T.; Takahashi, S.; Matsushita, M.; Narumi, Y.; Nakamura, H.

    1997-01-01

    Purpose: To evaluate the usefulness of the triple-lumen balloon catheter in the serial performance of CT arterial portography (CT-AP) and CT arteriography (CT-A). Material and Methods: A combined CT-AP and CT-A examination of 58 patients was carried out in which a cobra-type triple-lumen balloon catheter was used. CT-AP was performed by injecting contrast medium either into the splenic artery through a side-hole in the catheter proximal to the balloon inflated in the common hepatic artery, or into the superior mesentric artery through an end-hole in the catheter. Then CT-A was serially performed by delivering contrast medium either to the common hepatic artery or the proper hepatic artery from the end-hole, or to the accessory right hepatic artery through a side-hole proximal to the inflated balloon. Results: Sufficient CT-APs were obtained in 53 of the 58 patients (91%), CT-A in 42 (72%), and both in 42 (72%). Incomplete CT-AP was due to technical failure or anatomical anomaly, as was incomplete CT-A. No complications were seen. (orig.)

  10. 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.

  11. Semi-isolated, flat-topped carbonate platform (Oligo-Miocene, Sardinia, Italy): Sedimentary architecture and processes

    Science.gov (United States)

    Andreucci, Stefano; Pistis, Marco; Funedda, Antonio; Loi, Alfredo

    2017-11-01

    The Chattian-Aquitanian carbonate system of Isili sub-basin (SE Sardinia, Italy) were studied to better understand the hydrodynamic processes controlling the formation of landward-downlapping, rhodolith-rich, giant clinoforms. The studied flat-topped platform was attached to an island (semi-isolated) and migrated onshore (landward) over a shallow marine, protected embayment. The depositional profile is characterized by four, sea to land, zones: seaward slope, flat-topped platform (submerged flat), landward slope and mixed siliciclastic-carbonate embayment. In particular, these zones record different levels, from high to moderate, of hydrodynamic energy and persistency. The paleodepth of the studied succession, based on T/D test on Amphistegina specimens, red-algal genera and geometric reconstruction of the overall system, ranges from - 10 to - 30 m for the platform up to around - 40 m for the landward slope base. Thus, the flat-topped platform was permanently submerged and an extensive carbonate (sea grass, algal and bryozoan-algal) factory along with oyster framestones developed. The widespread presence in the barren zones of rhodolith-to-shell rich small to very small compound dunes (high-energy zone) suggests that the flat-topped platform was periodically swept by unidirectional, landward-directed currents. These currents allow the formation of large-scale, rhodolith-rich clinobeds along the landward slope (washover fan-like system). The presence of rodolith pavements developed along the flat-topped platform at or slightly below the fairweather wave base suggests that clinobeds were formed in a nearshore, shallow subtidal setting. Finally, the shallow marine, protected embayment (moderate-energy zone) represents the widening distal reaches of the currents flowing or along the clinoforms or from the coast basinward (river floods and/or ebb tidal currents). Despite few tidal-related sedimentary structures such as bi-directional ripples and small compound dunes

  12. 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...

  13. 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

  14. 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.

  15. Estimating effects of tidal power projects and climate change on threatened and endangered marine species and their food web.

    Science.gov (United States)

    Busch, D Shallin; Greene, Correigh M; Good, Thomas P

    2013-12-01

    Marine hydrokinetic power projects will operate as marine environments change in response to increased atmospheric carbon dioxide concentrations. We considered how tidal power development and stressors resulting from climate change may affect Puget Sound species listed under the U.S. Endangered Species Act (ESA) and their food web. We used risk tables to assess the singular and combined effects of tidal power development and climate change. Tidal power development and climate change posed risks to ESA-listed species, and risk increased with incorporation of the effects of these stressors on predators and prey of ESA-listed species. In contrast, results of a model of strikes on ESA-listed species from turbine blades suggested that few ESA-listed species are likely to be killed by a commercial-scale tidal turbine array. We applied scenarios to a food web model of Puget Sound to explore the effects of tidal power and climate change on ESA-listed species using more quantitative analytical techniques. To simulate development of tidal power, we applied results of the blade strike model. To simulate environmental changes over the next 50 years, we applied scenarios of change in primary production, plankton community structure, dissolved oxygen, ocean acidification, and freshwater flooding events. No effects of tidal power development on ESA-listed species were detected from the food web model output, but the effects of climate change on them and other members of the food web were large. Our analyses exemplify how natural resource managers might assess environmental effects of marine technologies in ways that explicitly incorporate climate change and consider multiple ESA-listed species in the context of their ecological community. Estimación de los Efectos de Proyectos de Energía de las Mareas y el Cambio Climático sobre Especies Marinas Amenazadas y en Peligro y su Red Alimentaria. © 2013 Society for Conservation Biology No claim to original US government works.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Soil Porewater Salinity Response to Sea-level Rise in Tidal Freshwater Forested Wetlands: A Modeling Study

    Science.gov (United States)

    Stagg, C. L.; Wang, H.; Krauss, K.; Conrads, P. A.; Swarzenski, C.; Duberstein, J. A.; DeAngelis, D.

    2017-12-01

    There is a growing concern about the adverse effects of salt water intrusion via tidal rivers and creeks into tidal freshwater forested wetlands (TFFWs) due to rising sea levels and reduction of freshwater flow. The distribution and composition of plant species, vegetation productivity, and biogeochemical functions including carbon sequestration capacity and flux rates in TFFWs have been found to be affected by increasing river and soil porewater salinities, with significant shifts occurring at a porewater salinity threshold of 3 PSU. However, the drivers of soil porewater salinity, which impact the health and ecological functions of TFFWs remains unclear, limiting our capability of predicting the future impacts of saltwater intrusion on ecosystem services provided by TFFWs. In this study, we developed a soil porewater salinity model for TFFWs based on an existing salt and water balance model with modifications to several key features such as the feedback mechanisms of soil salinity on evapotranspiration reduction and hydraulic conductivity. We selected sites along the floodplains of two rivers, the Waccamaw River (SC, USA) and the Savannah River (GA and SC, USA) that represent landscape salinity gradients of both surface water and soil porewater from tidal influence of the Atlantic Ocean. These sites represent healthy, moderately and highly salt-impacted forests, and oligohaline marshes. The soil porewater salinity model was calibrated and validated using field data collected at these sites throughout 2008-2016. The model results agreed well with field measurements. Analyses of the preliminary simulation results indicate that the magnitude, seasonal and annual variability, and duration of threshold salinities (e.g., 3 PSU) tend to vary significantly with vegetation status and type (i.e., healthy, degraded forests, and oligohaline marshes), especially during drought conditions. The soil porewater salinity model could be coupled with a wetland soil biogeochemistry

  1. Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity.

    Science.gov (United States)

    Efroimsky, Michael

    2015-10-01

    This is a pilot paper serving as a launching pad for study of orbital and spin evolution of binary asteroids. The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers kl divided by quality factors Q. Common in the literature is the (oftentimes illegitimate) approximation of the dynamical Love numbers with their static counterparts. Since the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: {k}l/Q\\propto 1/(μ Q). In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that overwhelmingly determines the tidal evolution is a product of the effective viscosity η by the tidal frequency χ . The functional form of the torque’s dependence on this product depends on who wins in the competition between viscosity and self-gravitation. Hence a quantitative criterion, to distinguish between two regimes. For higher values of η χ , we get {k}l/Q\\propto 1/(η χ ), {while} for lower values we obtain {k}l/Q\\propto η χ . Our study rests on an assumption that asteroids can be treated as Maxwell bodies. Applicable to rigid rocks at low frequencies, this approximation is used here also for rubble piles, due to the lack of a better model. In the future, as we learn more about mechanics of granular mixtures in a weak gravity field, we may have to amend the tidal theory with other rheological parameters, ones that do not show up in the description of viscoelastic bodies. This line of study provides

  2. In vivo measurement of intracellular pH in human brain during different tensions of carbon dioxide in arterial blood. A 31P-NMR study

    DEFF Research Database (Denmark)

    Jensen, K E; Thomsen, C; Henriksen, O

    1988-01-01

    The effect of changes in carbon dioxide tension in arterial blood upon intracellular pH in brain tissue was studied in seven healthy volunteers, aged 22-45 years. The pH changes were monitored by use of 31P nuclear magnetic resonance spectroscopy, performed on a whole-body 1.5 Tesla Siemens imaging...

  3. 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.

  4. 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.

  5. Carbon isotope evidence for a vigorous biological pump in the wake of end-Permian mass extinction

    Science.gov (United States)

    Meyer, K. M.; Yu, M.; Jost, A. B.; Payne, J.

    2009-12-01

    Ocean anoxia and euxinia have long been linked to the end-Permian mass extinction and the subsequent Early Triassic interval of delayed biotic recovery. This anoxic, sulfidic episode has been ascribed to both low- and high-productivity states in the marine water column, leaving the causes of euxinia and the mechanisms underlying delayed recovery poorly understood. To examine the nature of the end-Permian and Early Triassic biological production, we measured the carbon isotopic composition of carbonates from an exceptionally preserved carbonate platform in the Nanpanjiang Basin of south China. 13C of limestones from 5 stratigraphic sections displays a gradient of approximately 4‰ from shallow to deep water within the Lower Triassic. The limestones are systematically enriched in the platform interior relative to coeval slope and basin margin deposits by 2-4‰ at the peaks of correlative positive and negative δ13C excursions. This gradient subsequently collapses to less than 1‰ in the Middle Triassic, coincident with accelerated biotic recovery and cessation of δ13C excursions. Based on the relationship between δ18O and δ13C, trace metal analyses, and lithostratigraphic context, we conclude that the carbon isotope gradient is unlikely to reflect meteoric diagenesis, organic matter remineralization, or changes in the mixing ratio of sediment sources and minerals across the platform. Instead, we interpret the relatively depleted δ13C values toward the basin as reflecting DIC input from 13C-depleted deep waters during early diagenesis in a nutrient-rich, euxinic ocean. These observations suggest that a vigorous prokaryote-driven biological pump sustained Early Triassic ocean anoxia and inhibited recovery of animal ecosystems.

  6. 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.

  7. 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...

  8. 40 CFR 63.500 - Back-end process provisions-carbon disulfide limitations for styrene butadiene rubber by emulsion...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Back-end process provisions-carbon disulfide limitations for styrene butadiene rubber by emulsion processes. 63.500 Section 63.500 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR...

  9. TRANS-ARTERIAL EMBOLIZATION WITH N-BUTYL CYANOACRYLATE GLUE FOR RENAL BLEEDING: Case Report

    Directory of Open Access Journals (Sweden)

    Benny Young

    2014-08-01

    Full Text Available Background: The objectivity in management of renal bleeding is to preserve a significant renal parenchyma tissue and prevent associated morbidities like anemic shock or renal impairment from substantial nephron demise or obstructed uropathy. Trans-arterial embolization therapy by interventional radiology offers a high success rate with potential of reserving normal renal tissue. The selection material for renal arterial embolization largely depends on vasculature anatomy and end-point of procedure. N-butyl cyanoacrylate glue in our experience is applied in lesion supplied by small size of end-artery

  10. 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.

  11. Modeling effects of secondary tidal basins on estuarine morphodynamics

    Science.gov (United States)

    Nnafie, Abdel; Van Oyen, Tomas; De Maerschalck, Bart

    2017-04-01

    Many estuaries are situated in very densely populated areas with high economic activities that often conflict with their ecological values. For centuries, geometry and bathymetry of estuaries have been drastically modified trough engineering works such as embanking, sand extraction, channel deepening, land reclamations, etc. It is generally recognized that these works may increase the tidal range (e.g., Scheldt, Ems, Elbe) and turbidity (e.g., Loire, Ems) in estuaries [cf. Kerner, 2007; Wang et al., 2009; Winterwerp and Wang, 2013; Van Maren et al., 2015b,a]. In recent years, construction of secondary basins (also called retention basins) has gained increasing popularity among coastal managers to reduce tidal range and turbidity [Donner et al., 2012]. Previous studies have shown that location, geometry and number of secondary basins have a significant impact on tidal characteristics and sediment transport [Alebregtse and de Swart, 2014; Roos and Schuttelaars, 2015]. However, knowledge on how these secondary basins affect the morphodynamic development of estuaries on long time scales (order decades to centuries) is still lacking. The specific objectives of this study are twofold. First, to investigate effects of secondary basins on the long-term morphodynamic evolution of estuaries. In particular, effects of the presence of such a basin on the morphodynamic evolution of the main channel in the estuary and the physics underlying channel migration will be examined. For this, the Western Scheldt estuary (situated in the Netherlands) is used as a case study, which used to consist of multiple secondary tidal basins that were located at different positions in the estuary, and which have been gradually closed off between 1800 and 1968. Second, to systematically quantify sensitivity of model results to location, geometry, and to number of secondary basins. To this end, the state-of-the- art numerical model Delft3D is used, which has been successfully applied to

  12. Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features

    Science.gov (United States)

    Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.

    2015-12-01

    Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.

  13. 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.

  14. 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.

  15. Pseudoaneurysm of the Common Carotid Artery in an Infant due to Swallowed Fish Bone

    Directory of Open Access Journals (Sweden)

    Moulion Tapouh Jean Roger

    2015-01-01

    Full Text Available Carotid artery pseudoaneurysm is a rare condition, particularly in the paediatric population. Only about 30 cases of carotid artery aneurysms in infants have been published until now. This paper reports the case of a giant pseudoaneurysm of the left common carotid artery due to swallowed fish bone by an 8-year-old boy. This pseudoaneurysm was 5.5 cm transverse-diameter and resulted in severe respiratory distress. It was treated by resection and end-to-end anastomosis with satisfactory outcome after one-year follow-up. To the best of our knowledge, this is the largest carotid artery pseudoaneurysm ever described in children.

  16. 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

  17. Climate-related variation in plant peak biomass and growth phenology across Pacific Northwest tidal marshes

    Science.gov (United States)

    Buffington, Kevin J.; Dugger, Bruce D.; Thorne, Karen M.

    2018-03-01

    The interannual variability of tidal marsh plant phenology is largely unknown and may have important ecological consequences. Marsh plants are critical to the biogeomorphic feedback processes that build estuarine soils, maintain marsh elevation relative to sea level, and sequester carbon. We calculated Tasseled Cap Greenness, a metric of plant biomass, using remotely sensed data available in the Landsat archive to assess how recent climate variation has affected biomass production and plant phenology across three maritime tidal marshes in the Pacific Northwest of the United States. First, we used clipped vegetation plots at one of our sites to confirm that tasseled cap greenness provided a useful measure of aboveground biomass (r2 = 0.72). We then used multiple measures of biomass each growing season over 20-25 years per study site and developed models to test how peak biomass and the date of peak biomass varied with 94 climate and sea-level metrics using generalized linear models and Akaike Information Criterion (AIC) model selection. Peak biomass was positively related to total annual precipitation, while the best predictor for date of peak biomass was average growing season temperature, with the peak 7.2 days earlier per degree C. Our study provides insight into how plants in maritime tidal marshes respond to interannual climate variation and demonstrates the utility of time-series remote sensing data to assess ecological responses to climate stressors.

  18. Subclavian artery aneurysm in a patient with vascular Ehlers-Danlos syndrome.

    Science.gov (United States)

    Yasuda, Shota; Imoto, Kiyotaka; Uchida, Keiji; Uranaka, Yasuko; Kurosawa, Kenji; Masuda, Munetaka

    2016-02-01

    We describe our experience of surgical treatment in a 28-year-old woman with vascular Ehlers-Danlos syndrome. A right subclavian artery aneurysm was detected. The right vertebral artery arose from the aneurysm. Digital subtraction angiography showed interruption of the left vertebral artery. The aneurysm was excised and the right vertebral artery was anastomosed end-to-side to the right common carotid artery under deep hypothermia and circulatory arrest. The patient remained very well 4 years after surgery, with no late vascular complication. © The Author(s) 2014.

  19. 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...

  20. Constraining the Exchange of Carbon and Nitrogen in Eastern Long Island Sound

    Science.gov (United States)

    Byrd, A.; Warren, J. K.; Vlahos, P.; Whitney, M. M.

    2017-12-01

    Long Island Sound (LIS) is an urban estuary on the US east coast that undergoes seasonal hypoxia in its western and central regions. Currently, the budgets of both carbon and nitrogen in LIS remain unbalanced, despite their importance to the efficient and strategic management of the health of coastal and aquatic ecosystems. In this study, we evaluated the exchange values of C and N at the mouth of LIS (the Race), in order to constrain export through this important boundary. Discreet water samples were collected during four 15 km transects over the Race at five stations and three depths each station to resolve the temporal variability over a complete tidal cycle, in order to assess both net flux and variations across the tidal period. By evaluating both the particulate and dissolved pools of carbon (POC, PIC, DOC, DIC) and nitrogen (PON, DON, DIN) during the spring, summer and winter (high and low flow conditions) and pairing these measurements with physical data, we were able to identify a variety of forcing and export regimes. Preliminary results indicate the importance of spatial and tidal variability on flux estimates and show little or no export (and sometimes import) of nitrogen and significant export of organic carbon.

  1. Short-term tidal asymmetry inversion in a macrotidal estuary (Beira, Mozambique)

    Science.gov (United States)

    Nzualo, Teodósio N. M.; Gallo, Marcos N.; Vinzon, Susana B.

    2018-05-01

    The distortion of the tide in estuaries, bays and coastal areas is the result of the generation of overtides due to the non-linear effects associated with friction, advection, and the finite effects of the tidal amplitude in shallow waters. The Beira estuary is classified as macrotidal, with a large ratio of S2/M2. Typical tides ranges from 6 m and 0.8 m, during springs and neaps tides, respectively. As a consequence of this large fortnightly tidal amplitude difference and the estuarine morphology, asymmetry inversions occur. Two types of tidal asymmetries were investigated in this paper, one considering tidal duration asymmetry (time difference between rising and falling tide) and the other, related to tidal velocity asymmetry (unequal magnitudes of flood and ebb peaks currents). In the Beira estuary when we examine the tidal duration asymmetry, flood dominance is observed during spring tide periods (negative time difference between rising and falling tide), while ebb dominance appears during neap tides (positive time difference between rising and falling tide). A 2DH hydrodynamic model was implemented to analyze this asymmetry inversion. The model was calibrated with water-level data measured at the Port of Beira and current data measured along the estuary. The model was run for different scenarios considering tidal constituents at the ocean boundary, river discharge and the morphology of the estuary. River discharge did not show significant effects on the tidal duration asymmetry. Through comparison of the scenarios, it was shown that the incoming ocean tide at the boundary has an ebb-dominant asymmetry, changing to flood-dominant only during spring tides due to the effect of shoaling and friction within the estuary. During neap tides, the propagation occurs mainly in the channels, and ebb dominance remains. The interplay between the estuary morphodynamics was thus identified and the relation between tidal duration asymmetry and tidal velocity asymmetry was

  2. 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...

  3. 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.

  4. 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)

  5. Respiratory System Mechanics During Low Versus High Positive End-Expiratory Pressure in Open Abdominal Surgery: A Substudy of PROVHILO Randomized Controlled Trial

    NARCIS (Netherlands)

    D'Antini, Davide; Huhle, Robert; Herrmann, Jacob; Sulemanji, Demet S.; Oto, Jun; Raimondo, Pasquale; Mirabella, Lucia; Hemmes, Sabrine N. T.; Schultz, Marcus J.; Pelosi, Paolo; Kaczka, David W.; Vidal Melo, Marcos Francisco; Gama de Abreu, Marcelo; Cinnella, Gilda

    2018-01-01

    In the 2014 PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure (PROVHILO) trial, intraoperative low tidal volume ventilation with high positive end-expiratory pressure (PEEP = 12 cm H2O) and lung recruitment maneuvers did not decrease postoperative pulmonary complications

  6. 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

  7. Tidal power development -- A realistic, justifiable and topical problem of today

    International Nuclear Information System (INIS)

    Bernshtein, L.B.

    1995-01-01

    Modern tidal power plant designs have shown that with the use of large single-basin schemes, tidal power can be integrated with other forms of power generation. Tidal power is an environmentally benign means of producing electricity, particularly during off-peak demand. A number of tidal power schemes have been evaluated. These include Cumberland (1.4 Gigawatts (GW)), Cobequid (4.4 GW) in Canada; Sevrn (8.6 GW), Mersey (0.7 GW), Wyre (0.06 GW) and Conwy (0.03 GW) in Great Britain; Tugur (6.8 GW) in Russia and Garolim (0.5 GW) in South Korea. These schemes ar opening up future prospects for very large scale opportunities which could have global importance, for example, the transmission of 24 GW of electricity from tidal power plants in Great Britain to Europe. Another example is the potential transmission of 87 GW from Penzhinsh tidal power plant in Russia

  8. Palaeogeographic evolution of the marine Middle Triassic marine Germanic Basin changements - With emphasis on the carbonate tidal flat and shallow marine habitats of reptiles in Central Pangaea

    Science.gov (United States)

    Diedrich, Cajus G.

    2009-01-01

    More than seventy-five vertebrate track-sites have been found in Central Europe in 243-246.5 m.y. old Triassic coastal intertidal to sabkha carbonates. In the western part of the very flat Triassic intracontinental Germanic Basin, the carbonate strata contain at least 22 laterally extensive track horizons (called megatracksites). In contrast, in the eastern part of the basin only six megatracksites extended to near the centre of the Basin during marine low stands. Marine ingression and the development of extensive coastal marine environments began during the Aegean (Anisian) stage. This incursion began in the region of the eastern Carpathian and Silesian gates and spread westward due to the development of a tectonically controlled intracratonic basin. The tectonic origin of this basin made it susceptible to tsunamis and submarine earthquakes, which constituted very dangerous hazards for coastal terrestrial and even marine reptiles. The shallow sea that spread across the Germanic Basin produced extensive tidal flats that at times formed extensive inter-peninsular bridges between the Rhenish and Bohemian Massifs. The presence of these inter-peninsular bridges explains the observed distribution and movement of reptiles along coastal Europe and the northern Tethys Seaway during the Middle Triassic epoch. Two small reptiles, probably Macrocnemus and Hescherleria, left millions of tracks and trackways known as Rhynchosauroides and Procolophonichnium in the Middle Triassic coastal intertidal zone. The great abundance of their tracks indicates that their trackmakers Macrocnemus and Hescherleria were permanent inhabitants of this environment. In sharp contrast, tracks of other large terrestrial reptiles are quite rare along the coastal margins of the Germanic Basin, for example the recently discovered archaeosaur tracks and trackways referable to Isochirotherium, which most probably were made by the carnivore Ticinosuchus. Smaller medium-sized predatory thecodont reptiles

  9. 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

  10. Application of dead space fraction to titrate optimal positive end-expiratory pressure in an ARDS swine model.

    Science.gov (United States)

    Bian, Weishuai; Chen, Wei; Chao, Yangong; Wang, Lan; Li, Liming; Guan, Jian; Zang, Xuefeng; Zhen, Jie; Sheng, Bo; Zhu, Xi

    2017-04-01

    This study aimed to apply the dead space fraction [ratio of dead space to tidal volume (VD/VT)] to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS). Twelve swine models of ARDS were constructed. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H 2 O. The PEEP was reduced by 2 cm H 2 O every 10 min until 0 cm H 2 O was reached, and VD/VT was measured after each decrement step. VD/VT was measured using single-breath analysis of CO 2 , and calculated from arterial CO 2 partial pressure (PaCO 2 ) and mixed expired CO 2 (PeCO 2 ) using the following formula: VD/VT = (PaCO 2 - PeCO 2 )/PaCO 2 . The optimal PEEP was identified by the lowest VD/VT method. Respiration and hemodynamic parameters were recorded during the periods of pre-injury and injury, and at 4 and 2 cm H 2 O below and above the optimal PEEP (Po). The optimal PEEP in this study was found to be 13.25±1.36 cm H 2 O. During the Po period, VD/VT decreased to a lower value (0.44±0.08) compared with that during the injury period (0.68±0.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.

  11. TIDAL HEATING IN A MAGMA OCEAN WITHIN JUPITER’S MOON Io

    International Nuclear Information System (INIS)

    Tyler, Robert H.; Henning, Wade G.; Hamilton, Christopher W.

    2015-01-01

    Active volcanism observed on Io is thought to be driven by the temporally periodic, spatially differential projection of Jupiter's gravitational field over the moon. Previous theoretical estimates of the tidal heat have all treated Io as essentially a solid, with fluids addressed only through adjustment of rheological parameters rather than through appropriate extension of the dynamics. These previous estimates of the tidal response and associated heat generation on Io are therefore incomplete and possibly erroneous because dynamical aspects of the fluid behavior are not permitted in the modeling approach. Here we address this by modeling the partial-melt asthenosphere as a global layer of fluid governed by the Laplace Tidal Equations. Solutions for the tidal response are then compared with solutions obtained following the traditional solid-material approach. It is found that the tidal heat in the solid can match that of the average observed heat flux (nominally 2.25 W m −2 ), though only over a very restricted range of plausible parameters, and that the distribution of the solid tidal heat flux cannot readily explain a longitudinal shift in the observed (inferred) low-latitude heat fluxes. The tidal heat in the fluid reaches that observed over a wider range of plausible parameters, and can also readily provide the longitudinal offset. Finally, expected feedbacks and coupling between the solid/fluid tides are discussed. Most broadly, the results suggest that both solid and fluid tidal-response estimates must be considered in exoplanet studies, particularly where orbital migration under tidal dissipation is addressed

  12. Microphytobenthos potential productivity estimated in three tidal embayments of the San Francisco Bay system

    Science.gov (United States)

    Guarini, Jean-Marc; Cloern, James E.; Edmunds, Jody L.; Gros, Philippe

    2002-01-01

    In this paper we describe a three-step procedure to infer the spatial heterogeneity in microphytobenthos primary productivity at the scale of tidal estuaries and embayments. The first step involves local measurement of the carbon assimilation rate of benthic microalgae to determine the parameters of the photosynthesis-irradiance (P-E) curves (using non-linear optimization methods). In the next step, a resampling technique is used to rebuild pseudo-sampling distributions of the local productivity estimates; these provide error estimates for determining the significance level of differences between sites. The third step combines the previous results with deterministic models of tidal elevation and solar irradiance to compute mean and variance of the daily areal primary productivity over an entire intertidal mudflat area within each embayment. This scheme was applied on three different intertidal mudflat regions of the San Francisco Bay estuary during autumn 1998. Microphytobenthos productivity exhibits strong (ca. 3-fold) significant differences among the major sub-basins of San Francisco Bay. This spatial heterogeneity is attributed to two main causes: significant differences in the photosynthetic competence (P-E parameters) of the microphytobenthos in the different sub-basins, and spatial differences in the phase shifts between the tidal and solar cycles controlling the exposure of intertidal areas to sunlight. The procedure is general and can be used in other estuaries to assess the magnitude and patterns of spatial variability of microphytobenthos productivity at the level of the ecosystems.

  13. Refractory angina pectoris in end-stage coronary artery disease : Evolving therapeutic concepts

    NARCIS (Netherlands)

    Schoebel, FC; Frazier, OH; Jessurun, GAJ; DeJongste, MJL; Kadipasaoglu, KA; Jax, TW; Heintzen, MP; Cooley, DA; Strauer, BE; Leschke, M

    1997-01-01

    Refractory angina pectoris in coronary artery disease is defined as the persistence of severe anginal symptoms despite maximal conventional antianginal combination therapy. Further, the option to use an invasive revascularization procedure such as percutaneous coronary balloon angioplasty or

  14. 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.

  15. Multiscale heterogeneity characterization of tidal channel, tidal delta and foreshore facies, Almond Formation outcrops, Rock Springs uplift, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Schatzinger, R.A.; Tomutsa, L. [BDM Petroleum Technologies, Bartlesville, OK (United States)

    1997-08-01

    In order to accurately predict fluid flow within a reservoir, variability in the rock properties at all scales relevant to the specific depositional environment needs to be taken into account. The present work describes rock variability at scales from hundreds of meters (facies level) to millimeters (laminae) based on outcrop studies of the Almond Formation. Tidal channel, tidal delta and foreshore facies were sampled on the eastern flank of the Rock Springs uplift, southeast of Rock Springs, Wyoming. The Almond Fm. was deposited as part of a mesotidal Upper Cretaceous transgressive systems tract within the greater Green River Basin. Bedding style, lithology, lateral extent of beds of bedsets, bed thickness, amount and distribution of depositional clay matrix, bioturbation and grain sorting provide controls on sandstone properties that may vary more than an order of magnitude within and between depositional facies in outcrops of the Almond Formation. These features can be mapped on the scale of an outcrop. The products of diagenesis such as the relative timing of carbonate cement, scale of cemented zones, continuity of cemented zones, selectively leached framework grains, lateral variability of compaction of sedimentary rock fragments, and the resultant pore structure play an equally important, although less predictable role in determining rock property heterogeneity. A knowledge of the spatial distribution of the products of diagenesis such as calcite cement or compaction is critical to modeling variation even within a single facies in the Almond Fin. because diagenesis can enhance or reduce primary (depositional) rock property heterogeneity. Application of outcrop heterogeneity models to the subsurface is greatly hindered by differences in diagenesis between the two settings. The measurements upon which this study is based were performed both on drilled outcrop plugs and on blocks.

  16. 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.)

  17. Role of tidal flat in material cycling in the coastal sea

    OpenAIRE

    Yara, Yumiko; Yanagi, Tetsuo; Montani, Shigeru; Kuninao, Tada

    2007-01-01

    A simple tidal flat model with pelagic and benthic ecosystems was developed in order to analyze the nitrogen cycling in an inter-tidal flat of the Seto Inland Sea, Japan. After the verification of calculation results with the observed results in water quality and benthic biomasses, the role of this tidal flat in nitrogen cycling was evaluated from the viewpoint of water quality purification capability. When there is no suspension feeder in the tidal flat, the water quality purification capab...

  18. 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

  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. Human responses to carbon dioxide, a follow-up study at recommended exposure limits in non-industrial environments

    DEFF Research Database (Denmark)

    Zhang, Xiaojing; Wargocki, Pawel; Lian, Zhiwei

    2016-01-01

    To extend the results of a previous study on the effects of carbon dioxide (CO2) and bioeffluents on humans, the new study reported in this paper was carried out. The purpose of this study was to examine, whether exposure to CO2 at 5000 ppm would cause sensory discomfort, evoke acute health...... no effect on perceived air quality or physiological responses except for end-tidal CO2 (ETCO2), which increased more (to 5.3 kPa) than it was in the reference condition (5.1 kPa). Other results indicate additionally that a 2.5-h exposure to CO2 up to 5000 ppm did not increase intensity of health symptoms...

  1. 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.

  2. Detomidine and the combination of detomidine and MK-467, a peripheral alpha-2 adrenoceptor antagonist, as premedication in horses anaesthetized with isoflurane.

    Science.gov (United States)

    Pakkanen, Soile Ae; Raekallio, Marja R; Mykkänen, Anna K; Salla, Kati M; de Vries, Annemarie; Vuorilehto, Lauri; Scheinin, Mika; Vainio, Outi M

    2015-09-01

    To investigate MK-467 as part of premedication in horses anaesthetized with isoflurane. Experimental, crossover study with a 14 day wash-out period. Seven healthy horses. The horses received either detomidine (20 μg kg(-1) IV) and butorphanol (20 μg kg(-1) IV) alone (DET) or with MK-467 (200 μg kg(-1) IV; DET + MK) as premedication. Anaesthesia was induced with ketamine (2.2 mg kg(-1) ) and midazolam (0.06 mg kg(-1) ) IV and maintained with isoflurane. Heart rate (HR), mean arterial pressure (MAP), end-tidal isoflurane concentration, end-tidal carbon dioxide tension, central venous pressure, fraction of inspired oxygen (FiO2 ) and cardiac output were recorded. Blood samples were taken for blood gas analysis and to determine plasma drug concentrations. The cardiac index (CI), systemic vascular resistance (SVR), ratio of arterial oxygen tension to inspired oxygen (Pa O2 /FiO2 ) and tissue oxygen delivery (DO2 ) were calculated. Repeated measures anova was applied for HR, CI, MAP, SVR, lactate and blood gas variables. The Student's t-test was used for pairwise comparisons of drug concentrations, induction times and the amount of dobutamine administered. Significance was set at p detomidine concentrations were reduced in the group receiving MK-467. After DET+MK, the area under the plasma concentration time curve of butorphanol was smaller. MK-467 enhances cardiac function and tissue oxygen delivery in horses sedated with detomidine before isoflurane anaesthesia. This finding could improve patient safety in the perioperative period. The dosage of MK-467 needs to be investigated to minimise the effect of MK-467 on MAP. © 2014 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  3. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  4. Surface evolution and carbon sequestration in disturbed and undisturbed wetland soils of the Hunter estuary, southeast Australia

    Science.gov (United States)

    Howe, A. J.; Rodríguez, J. F.; Saco, P. M.

    2009-08-01

    The aim of this work was to quantify the soil carbon storage and sequestration rates of undisturbed natural wetlands and disturbed wetlands subject to restriction of tidal flow and subsequent rehabilitation in an Australian estuary. Disturbed and undisturbed estuarine wetlands of the Hunter estuary, New South Wales, Australia were selected as the study sites for this research. Vertical accretion rates of estuarine substrates were combined with soil carbon concentrations and bulk densities to determine the carbon store and carbon sequestration rates of the substrates tested. Relationships between estuary water level, soil evolution and vertical accretion were also examined. The carbon sequestration rate of undisturbed wetlands was lower (15% for mangrove and 55% for saltmarsh) than disturbed wetlands, but the carbon store was higher (65% for mangrove and 60% for saltmarsh). The increased carbon sequestration rate of the disturbed wetlands was driven by substantially higher rates of vertical accretion (95% for mangrove and 345% for saltmarsh). Estuarine wetland carbon stores were estimated at 700-1000 Gg C for the Hunter estuary and 3900-5600 Gg C for New South Wales. Vertical accretion and carbon sequestration rates of estuarine wetlands in the Hunter are at the lower end of the range reported in the literature. The comparatively high carbon sequestration rates reported for the disturbed wetlands in this study indicate that wetland rehabilitation has positive benefits for regulation of atmospheric carbon concentrations, in addition to more broadly accepted ecosystem services.

  5. Estimation of River Pollution Index in a Tidal Stream Using Kriging Analysis

    Directory of Open Access Journals (Sweden)

    Chiang Wei

    2012-08-01

    Full Text Available Tidal streams are complex watercourses that represent a transitional zone between riverine and marine systems; they occur where fresh and marine waters converge. Because tidal circulation processes cause substantial turbulence in these highly dynamic zones, tidal streams are the most productive of water bodies. Their rich biological diversity, combined with the convenience of land and water transports, provide sites for concentrated populations that evolve into large cities. Domestic wastewater is generally discharged directly into tidal streams in Taiwan, necessitating regular evaluation of the water quality of these streams. Given the complex flow dynamics of tidal streams, only a few models can effectively evaluate and identify pollution levels. This study evaluates the river pollution index (RPI in tidal streams by using kriging analysis. This is a geostatistical method for interpolating random spatial variation to estimate linear grid points in two or three dimensions. A kriging-based method is developed to evaluate RPI in tidal streams, which is typically considered as 1D in hydraulic engineering. The proposed method efficiently evaluates RPI in tidal streams with the minimum amount of water quality data. Data of the Tanshui River downstream reach available from an estuarine area validate the accuracy and reliability of the proposed method. Results of this study demonstrate that this simple yet reliable method can effectively estimate RPI in tidal streams.

  6. 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

  7. 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...

  8. 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.

  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. [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

  11. Strategies for the Use of Tidal Stream Currents for Power Generation

    Science.gov (United States)

    Orhan, Kadir; Mayerle, Roberto

    2015-04-01

    Indonesia is one of the priority countries in Southeast Asia for the development of ocean renewable energy facilities and The National Energy Council intends to increase the role of ocean energy significantly in the energy mix for 2010-2050. To this end, the joint German-Indonesian project "Ocean Renewable Energy ORE-12" aims at the identification of marine environments in the Indonesian Archipelago, which are suitable for the efficient generation of electric power by converter facilities. This study, within the ORE-12 project, is focused on the tidal stream currents on the straits between the Indian Ocean and Flores Sea to estimate the energy potentials and to develop strategies for producing renewable energy. FLOW module of Delft3D has been used to run hydrodynamic models for site assessment and design development. In site assessment phase, 2D models have been operated for a-month long periods and with a resolution of 500 m. Later on, in design development phase, detailed 3D models have been developed and operated for three-month long periods and with a resolution of 50 m. Bathymetric data for models have been obtained from the GEBCO_08 Grid and wind data from the Global Forecast System of NOAA's National Climatic Data Center. To set the boundary conditions of models, tidal forcing with 11 harmonic constituents was supplied from TPXO Indian Ocean Atlas (1/12° regional model) and data from HYCOM+NCODA Global 1/12° Analysis have been used to determine salinity and temperature on open boundaries. After the field survey is complete, water level time-series supplied from a tidal gauge located in the domain of interest (8° 20΄ 9.7" S, 122° 54΄ 51.9" E) have been used to verify the models and then energy potentials of the straits have been estimated. As a next step, correspondence between model outputs and measurements taken by the radar system of TerraSAR-X satellite (DLR) will be analysed. Also for the assessment of environmental impacts caused by tidal stream

  12. 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...

  13. 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)

  14. 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.

  15. 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.

  16. Enhancing local distinctiveness fosters public acceptance of tidal energy: A UK case study

    International Nuclear Information System (INIS)

    Devine-Wright, Patrick

    2011-01-01

    Tidal energy has the technical potential to form part of a low carbon electricity sector, however, its 'social potential' is less clear, as few empirical studies of public beliefs and responses have been conducted to date. This research addressed this gap by investigating a tidal energy convertor in Northern Ireland, said to be the first grid-connected device of its kind in the world. Data was collected from 313 residents of two nearby villages using mixed methods, guided by a conceptual framework that avoided 'NIMBY' assumptions and instead drew on place theory. Findings indicated strong support for the project, arising from beliefs that the project enhanced local distinctiveness by 'putting the area on the map worldwide'; appeared visually familiar and helped tackle climate change. These positive beliefs outweighed concerns about outcome and process aspects, which were preponderant in one of the two villages. The project was interpreted to have few positive local economic outcomes, to potentially threaten local livelihoods and local ecology. Moreover, residents expressed cynicism about consultation procedures, and reported low levels of behavioural engagement. Implications of the findings for the literature on public acceptance of renewable energy, and for the emerging marine energy sector specifically, are discussed.

  17. 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...

  18. 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

  19. 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.

  20. Sequential development of tidal ravinement surfaces in macro- to hypertidal estuaries with high volcaniclastic input: the Miocene Puerto Madryn Formation (Patagonia, Argentina)

    Science.gov (United States)

    Scasso, Roberto A.; Cuitiño, José I.

    2017-08-01