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Sample records for oximetry wave variation

  1. Variations in physician interpretation of overnight pulse oximetry monitoring.

    PubMed

    Ramsey, Rory; Mehra, Reena; Strohl, Kingman P

    2007-09-01

    Overnight pulse oximetry is commonly used for hypoxemia evaluation in patients with COPD and sleep-disordered breathing. There is little information regarding its impact on physician decision making, and therefore an important measure of its clinical utility is untested and unknown. The aim of this study was to describe physician interpretation, use, and opinions regarding overnight pulse oximetry. Forty-one pulmonary physicians and fellows participated in structured interviews consisting of three oximetry record interpretations, oral responses to a standard question set, and a questionnaire. Qualitative data were analyzed using an open coding process. Quantitative data were assessed for distributions. Four measures were consistently used by the majority of physicians in record interpretation: background information, arterial oxygen saturation measured by pulse oximetry (Spo(2)) waveform and pattern, and time spent with Spo(2) < 90%. An additional 10 measures were consistently used by 5 to 46% of physicians. No interpretation generated a recommendation with > 60% consensus. There was a wide range of opinions on important matters related to this test, including test utility, indications, variables considered most important for interpretation, and criteria for nocturnal oxygen prescription. Forty-one physicians provided 35 different opinions on when nocturnal supplemental oxygen should be initiated. The variation in physician interpretation, use, and opinions regarding overnight pulse oximetry calls into question its clinical utility and underscores a need for standardization of presentation, training, and interpretation.

  2. Pulse oximetry

    PubMed Central

    Jubran, Amal

    1999-01-01

    Pulse oximetry is one of the most commonly employed monitoringmodalities in the critical care setting. This review describes the latesttechnological advances in the field of pulse oximetry. Accuracy of pulseoximeters and their limitations are critically examined. Finally, the existingdata regarding the clinical applications and cost-effectiveness of pulseoximeters are discussed. PMID:11094477

  3. Higher temporal resolution is necessary for continuous-wave near -infrared spectrophotometric monitors in both cerebral and muscular tissue oximetry

    NASA Astrophysics Data System (ADS)

    Chihara, Eiichi; Shiga, Toshikazu; Tanabe, Kazuhisa; Tanaka, Yoshifumi

    1998-01-01

    Conventional near infrared spectrophotometric monitors have temporal resolution of less than about 1 Hz. However, physiological Hb signals such as pulsation and muscle contraction have higher frequency than 1 Hz. Insufficient sampling rates inevitably lead aliasing of the recorded signals in tissue oximetry for both brain and muscle. Cerebral Hb signals (57 y.o. female artificially ventilated under general anesthesia) and thigh muscle (22 y.o. male with 20 W - 240 W exercise at 1 Hz cycling in semirecumbent ergometer) were measured with NIRS monitor with temporal resolution of 10 Hz (OMRON Co. Ltd., Japan). The detail of physiological fluctuations such as pulsation, ventilation, and muscle pumping was clearly recognized with a 10 Hz sampling. The comparison with recalculated waveforms at slower sampling rate (0.5 Hz, 1 Hz, 2 Hz) revealed that with slower sampling than 1 Hz cerebral respiratory waves were deformed by pulsation, and that magnitudes of muscle pumping could not be properly evaluated in dynamic exercise. In both pulsatile and muscle contractile cycle a phase delay between oxygenated component and deoxygenated one was also detected, which has been overlooked by conventional NIRS monitoring.

  4. Higher temporal resolution is necessary for continuous-wave near -infrared spectrophotometric monitors in both cerebral and muscular tissue oximetry

    NASA Astrophysics Data System (ADS)

    Chihara, Eiichi; Shiga, Toshikazu; Tanabe, Kazuhisa; Tanaka, Yoshifumi

    1997-12-01

    Conventional near infrared spectrophotometric monitors have temporal resolution of less than about 1 Hz. However, physiological Hb signals such as pulsation and muscle contraction have higher frequency than 1 Hz. Insufficient sampling rates inevitably lead aliasing of the recorded signals in tissue oximetry for both brain and muscle. Cerebral Hb signals (57 y.o. female artificially ventilated under general anesthesia) and thigh muscle (22 y.o. male with 20 W - 240 W exercise at 1 Hz cycling in semirecumbent ergometer) were measured with NIRS monitor with temporal resolution of 10 Hz (OMRON Co. Ltd., Japan). The detail of physiological fluctuations such as pulsation, ventilation, and muscle pumping was clearly recognized with a 10 Hz sampling. The comparison with recalculated waveforms at slower sampling rate (0.5 Hz, 1 Hz, 2 Hz) revealed that with slower sampling than 1 Hz cerebral respiratory waves were deformed by pulsation, and that magnitudes of muscle pumping could not be properly evaluated in dynamic exercise. In both pulsatile and muscle contractile cycle a phase delay between oxygenated component and deoxygenated one was also detected, which has been overlooked by conventional NIRS monitoring.

  5. Respiratory variations in the photoplethysmographic waveform amplitude depend on type of pulse oximetry device.

    PubMed

    Høiseth, Lars Øivind; Hoff, Ingrid Elise; Hagen, Ove Andreas; Kirkebøen, Knut Arvid; Landsverk, Svein Aslak

    2016-06-01

    Respiratory variations in the photoplethysmographic waveform amplitude predict fluid responsiveness under certain conditions. Processing of the photoplethysmographic signal may vary between different devices, and may affect respiratory amplitude variations calculated by the standard formula. The aim of the present analysis was to explore agreement between respiratory amplitude variations calculated using photoplethysmographic waveforms available from two different pulse oximeters. Analysis of registrations before and after fluid loads performed before and after open-heart surgery (aortic valve replacement and/or coronary artery bypass grafting) with patients on controlled mechanical ventilation. Photoplethysmographic (Nellcor and Masimo pulse oximeters) and arterial pressure waveforms were recorded. Amplitude variations induced by ventilation were calculated and averaged over ten respiratory cycles. Agreements for absolute values are presented in scatterplots (with least median square regression through the origin, LMSO) and Bland-Altman plots. Agreement for trending presented in a four-quadrant plot. Agreement between respiratory photoplethysmographic amplitude variations from the two pulse oximeters was poor with LMSO ΔPOPNellc = 1.5 × ΔPOPMas and bias ± limits of agreement 7.4 ± 23 %. Concordance rate with a fluid load was 91 %. Agreement between respiratory variations in the photoplethysmographic waveform amplitude calculated from the available signals output by two different pulse oximeters was poor, both evaluated by LMSO and Bland-Altman plot. Respiratory amplitude variations from the available signals output by these two pulse oximeters are not interchangeable.

  6. Pulse oximetry in pediatric practice.

    PubMed

    Fouzas, Sotirios; Priftis, Kostas N; Anthracopoulos, Michael B

    2011-10-01

    The introduction of pulse oximetry in clinical practice has allowed for simple, noninvasive, and reasonably accurate estimation of arterial oxygen saturation. Pulse oximetry is routinely used in the emergency department, the pediatric ward, and in pediatric intensive and perioperative care. However, clinically relevant principles and inherent limitations of the method are not always well understood by health care professionals caring for children. The calculation of the percentage of arterial oxyhemoglobin is based on the distinct characteristics of light absorption in the red and infrared spectra by oxygenated versus deoxygenated hemoglobin and takes advantage of the variation in light absorption caused by the pulsatility of arterial blood. Computation of oxygen saturation is achieved with the use of calibration algorithms. Safe use of pulse oximetry requires knowledge of its limitations, which include motion artifacts, poor perfusion at the site of measurement, irregular rhythms, ambient light or electromagnetic interference, skin pigmentation, nail polish, calibration assumptions, probe positioning, time lag in detecting hypoxic events, venous pulsation, intravenous dyes, and presence of abnormal hemoglobin molecules. In this review we describe the physiologic principles and limitations of pulse oximetry, discuss normal values, and highlight its importance in common pediatric diseases, in which the principle mechanism of hypoxemia is ventilation/perfusion mismatch (eg, asthma exacerbation, acute bronchiolitis, pneumonia) versus hypoventilation (eg, laryngotracheitis, vocal cord dysfunction, foreign-body aspiration in the larynx or trachea). Additional technologic advancements in pulse oximetry and its incorporation into evidence-based clinical algorithms will improve the efficiency of the method in daily pediatric practice.

  7. Evaluating cost and resource use associated with pulse oximetry screening for critical congenital heart disease: Empiric estimates and sources of variation.

    PubMed

    Reeder, Matthew R; Kim, Jaewhan; Nance, Amy; Krikov, Sergey; Feldkamp, Marcia L; Randall, Harper; Botto, Lorenzo D

    2015-11-01

    Newborn screening for critical congenital heart disease (CCHD) using pulse oximetry is being implemented in the United States and internationally; however, few data are available on the associated in-hospital costs and use of resources. Time and motion study in well-baby nurseries at two large urban hospitals in Utah using different approaches to pulse oximetry screening. Two observers recorded the time for each screening step together with provider and equipment characteristics. Structured questionnaire provided additional information on labor and equipment costs. Fifty-three CCHD screens were observed. At site A (n = 22), screening was mostly done by medical assistants (95%) using disposable probes (100%); at site B (n = 31), screening was mostly performed by certified nursing assistants (90%) using reusable probes (90%). Considering only first screens (n = 53), the median screen time was 8.6 min (range: 3.2-23.2), with no significant difference between sites. The overall cost ($ in 2014) of screening per baby was $24.52 at site A and $2.60 at site B. Nearly all the variation in cost (90%) was due to the cost of disposable probes; labor costs were similar between sites. CCHD screening by means of pulse oximetry is reasonably fast for most babies, leading to relative small labor costs with little variation by provider type. The main driver of costs is equipment: in a high throughput setting, reusable probes are currently associated with considerable cost saving compared with disposable probes. As programs expand to universal screening, improved and cheaper technologies could lead to considerable economies of scale. © 2015 Wiley Periodicals, Inc.

  8. Variational principles for dissipative waves

    NASA Astrophysics Data System (ADS)

    Dodin, I. Y.; Ruiz, D. E.

    2016-10-01

    Variational methods are a powerful tool in plasma theory. However, their applications are typically restricted to conservative systems or require doubling of variables, which often contradicts the purpose of the variational approach altogether. We show that these restrictions can be relaxed for some classes of dynamical systems that are of practical interest in plasma physics, particularly including dissipative plasma waves. Applications will be discussed to calculating dispersion relations and modulational dynamics of individual plasma waves and wave ensembles. The work was supported by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

  9. Cerebral oximetry: a replacement for pulse oximetry?

    PubMed

    Frost, Elizabeth A M

    2012-10-01

    Cerebral oximetry has been around for some 3 decades but has had a somewhat checkered history regarding application and reliability. More recently several monitors have been approved in the United States and elsewhere and the technique is emerging as a useful tool for assessing not only adequate cerebral oxygenation but also tissue oxygenation and perfusion in other organs.

  10. Pathway to Retinal Oximetry

    PubMed Central

    Beach, James

    2014-01-01

    Events and discoveries in oxygen monitoring over the past two centuries are presented as the background from which oximetry of the human retina evolved. Achievements and the people behind them are discussed, showing parallels between the work in tissue measurements and later in the eye. Developments in the two-wavelength technique for oxygen saturation measurements in retinal vessels are shown to exploit the forms of imaging technology available over time. The last section provides a short summary of the recent research in retinal diseases using vessel oximetry. PMID:25237591

  11. Pathway to Retinal Oximetry.

    PubMed

    Beach, James

    2014-09-01

    Events and discoveries in oxygen monitoring over the past two centuries are presented as the background from which oximetry of the human retina evolved. Achievements and the people behind them are discussed, showing parallels between the work in tissue measurements and later in the eye. Developments in the two-wavelength technique for oxygen saturation measurements in retinal vessels are shown to exploit the forms of imaging technology available over time. The last section provides a short summary of the recent research in retinal diseases using vessel oximetry.

  12. Calibration of Contactless Pulse Oximetry

    PubMed Central

    Bartula, Marek; Bresch, Erik; Rocque, Mukul; Meftah, Mohammed; Kirenko, Ihor

    2017-01-01

    BACKGROUND: Contactless, camera-based photoplethysmography (PPG) interrogates shallower skin layers than conventional contact probes, either transmissive or reflective. This raises questions on the calibratability of camera-based pulse oximetry. METHODS: We made video recordings of the foreheads of 41 healthy adults at 660 and 840 nm, and remote PPG signals were extracted. Subjects were in normoxic, hypoxic, and low temperature conditions. Ratio-of-ratios were compared to reference Spo2 from 4 contact probes. RESULTS: A calibration curve based on artifact-free data was determined for a population of 26 individuals. For an Spo2 range of approximately 83% to 100% and discarding short-term errors, a root mean square error of 1.15% was found with an upper 99% one-sided confidence limit of 1.65%. Under normoxic conditions, a decrease in ambient temperature from 23 to 7°C resulted in a calibration error of 0.1% (±1.3%, 99% confidence interval) based on measurements for 3 subjects. PPG signal strengths varied strongly among individuals from about 0.9 × 10−3 to 4.6 × 10−3 for the infrared wavelength. CONCLUSIONS: For healthy adults, the results present strong evidence that camera-based contactless pulse oximetry is fundamentally feasible because long-term (eg, 10 minutes) error stemming from variation among individuals expressed as A*rms is significantly lower (<1.65%) than that required by the International Organization for Standardization standard (<4%) with the notion that short-term errors should be added. A first illustration of such errors has been provided with A**rms = 2.54% for 40 individuals, including 6 with dark skin. Low signal strength and subject motion present critical challenges that will have to be addressed to make camera-based pulse oximetry practically feasible. PMID:27258081

  13. Photonic textiles for pulse oximetry.

    PubMed

    Rothmaier, Markus; Selm, Bärbel; Spichtig, Sonja; Haensse, Daniel; Wolf, Martin

    2008-08-18

    Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

  14. Pulse oximetry as a diagnostic tool in dental medicine

    NASA Astrophysics Data System (ADS)

    Kosturkov, D.; Uzunov, Ts.; Uzunova, P.

    2016-01-01

    One of the most widespread optical methods used in biophotonics is the pulse oximetry, which is based on the measurement of light-modulated pulse wave of blood. This is a non-invasive, objective method for evaluation of the blood supply. Recently it has become very popular in dental medicine for the measurement of the condition of pulp microcirculation. The aim of our research is to evaluate the possibilities of pulse oximetry for estimation the pulp microcirculation in intact teeth among young patients. Results obtained clearly show that this method can be applied to assess the pulp condition and could be used in clinical practice in combination with other diagnostic methods.

  15. Lanczos steps to improve variational wave functions

    NASA Astrophysics Data System (ADS)

    Becca, Federico; Hu, Wen-Jun; Iqbal, Yasir; Parola, Alberto; Poilblanc, Didier; Sorella, Sandro

    2015-09-01

    Gutzwiller-projected fermionic states can be efficiently implemented within quantum Monte Carlo calculations to define extremely accurate variational wave functions for Heisenberg models on frustrated two-dimensional lattices, not only for the ground state but also for low-energy excitations. The application of few Lanczos steps on top of these states further improves their accuracy, allowing calculations on large clusters. In addition, by computing both the energy and its variance, it is possible to obtain reliable estimations of exact results. Here, we report the cases of the frustrated Heisenberg models on square and Kagome lattices.

  16. Pulse oximetry in the oesophagus.

    PubMed

    Kyriacou, P A

    2006-01-01

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO(2)) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Since central blood flow may be preferentially preserved, this review explores a new alternative site, the oesophagus, for monitoring blood oxygen saturation by pulse oximetry. This review article presents the basic physics, technology and applications of pulse oximetry including photoplethysmography. The limitations of this technique are also discussed leading to the proposed development of the oesophageal pulse oximeter. In the majority, the report will be focused on the description of a new oesophageal photoplethysmographic/SpO(2) probe, which was developed to investigate the suitability of the oesophagus as an alternative monitoring site for the continuous measurement of SpO(2) in cases of poor peripheral circulation. The article concludes with a review of reported clinical investigations of the oesophageal pulse oximeter.

  17. Feasibility and accuracy of nasal alar pulse oximetry.

    PubMed

    Morey, T E; Rice, M J; Vasilopoulos, T; Dennis, D M; Melker, R J

    2014-06-01

    The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a novel pulse oximetry sensor custom designed for the nasal ala. After IRB approval, healthy non-smoking subjects [n=12; aged 28 (23-41) yr; 6M/6F] breathed hypoxic mixtures of fresh gas by a facemask to achieve oxyhaemoglobin saturations of 70-100% measured by traditional co-oximetry from radial artery samples. Concurrent alar and finger pulse oximetry values were measured using probes designed for these sites. Data were analysed using the Bland-Altman method for multiple observations per subject. Bias, precision, and accuracy root mean square error (ARMS) over a range of 70-100% were significantly better for the alar probe compared with a standard finger probe. The mean bias for the alar and finger probes was 0.73% and 1.90% (P<0.001), respectively, with corresponding precision values of 1.65 and 1.83 (P=0.015) and ARMS values of 1.78% and 2.72% (P=0.047). The coefficients of determination were 0.96 and 0.96 for the alar and finger probes, respectively. The within/between-subject variation for the alar and finger probes were 1.14/1.57% and 1.87/1.47%, respectively. The limits of agreement were 3.96/-2.50% and 5.48/-1.68% for the alar and finger probes, respectively. Nasal alar pulse oximetry is feasible and demonstrates accurate pulse oximetry values over a range of 70-100%. The alar probe demonstrated greater accuracy compared with a conventional finger pulse oximeter. © The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Wave groupiness variations in the nearshore

    USGS Publications Warehouse

    List, J.H.

    1991-01-01

    This paper proposes a new definition of the groupiness factor, GF, based on the envelope of the incident-wave time series. It is shown that an envelope-based GF has several important advantages over the SIWEH-based groupiness factor, including objective criteria for determining the accuracy of the envelope function and well-defined numerical limits. Using this new GF, the variability of incident wave groupiness in the field is examined both temporally, in unbroken waves at a fixed location, and spatially, in a cross-shore array through the surf zone. Contrary to previous studies using the SIWEH-based GF, results suggest that incident wave groupiness may not be an independent parameter in unbroken waves; through a wide range of spectral shapes, from swell to storm waves, the groupiness did not vary significantly. As expected, the groupiness decreases rapidly as waves break through the surf zone, although significant wave height variability persists even through a saturated surf zone. The source of this inner surf zone groupiness is not identified; however, this observation implies that models of long wave generation must account for nonsteady radiation stress gradients landward of some narrow zone near the mean breakpoint. ?? 1991.

  19. Wearable Oximetry for Harsh Environments

    DTIC Science & Technology

    2017-04-26

    to this, commercial oximetry sensors (e.g., from Masimo, BSX Insight, Cercacor) are now being marketed for enhancing performance of elite athletes...to detect and mitigate motion artifacts when possible. Example results from one approach to detect signal segments of sufficient quality to extract...pressure starting at 15 s, 10 mA LED current, sitting. Figure 4. Example a) high and b) low quality IR signal segments selected by automated

  20. Wearable oximetry for harsh environments

    DTIC Science & Technology

    2017-02-23

    than ±10 bpm,  Be wearable, and compatible with equipment,  Have a battery life of at least three days,  Include signal processing that...our work only considers reflective-mode oximetry, which is required for the sternum or forehead. A miniature battery -free oximeter has recently...oximeter to operate well over three days with a 100 mAh battery . Battery life may be further extended, after testing with users determines how often SpO2

  1. Pulseless Oximetry: A Preliminary Evaluation.

    PubMed

    Aldrich, Thomas K; Gupta, Pragya; Stoy, Sean P; Carlese, Anthony; Goldstein, Daniel J

    2015-12-01

    Pulse oximetry fails when pulsations are weak or absent, common in patients with continuous flow left ventricular assist devices (LVADs). We developed a method to measure arterial oxygenation (Sao2) noninvasively in pulseless patients with LVADs. The technique involves 5- to 10-s occlusions of radial and ulnar arteries on one hand. A fingertip is transilluminated alternately with light-emitting diodes emitting 660 nm (red) and 905 nm (infrared). During the approximately 1 s after release of occlusion, changing attenuance of each wavelength is measured and their red/infrared arterial blood attenuance ratio (R/IR) calculated. We studied five normal subjects breathing hyperoxic, normoxic, or hypoxic gas mixtures to establish a calibration curve, using standard pulse oximetry as the gold standard. We also studied seven pulseless patients with LVADs (two studied twice) at clinically determined oxygenation. Normal subject data showed close correlation of oxygen saturation by pulse oximetry (Spo2) with R/IR, (Spo2 = 111 - [26.7 × R/IR]; R2 = 0.975). For patients with LVADs, predicted Sao2 (from the calibration curve) tended to underestimate measured Sao2 (from arterial blood) by a clinically insignificant 1.1 ± 1.6 percentage points (mean ± SD), maximum 3.4 percentage points. Preliminary results in a small number of patients demonstrate that pulseless oximetry can be used to estimate arterial saturation with acceptable accuracy. A noninvasive oximeter that does not rely on pulsatile flow would be a valuable advance in assessing oxygenation in patients with LVADs, for whom the only current option is arterial puncture, which is painful, risks arterial injury, and only provides a snapshot evaluation of oxygenation.

  2. Optimal filter bandwidth for pulse oximetry

    NASA Astrophysics Data System (ADS)

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  3. Optimal filter bandwidth for pulse oximetry.

    PubMed

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  4. Impact of ENSO on seasonal variations of Kelvin Waves and mixed Rossby-Gravity Waves

    NASA Astrophysics Data System (ADS)

    Rakhman, Saeful; Lubis, Sandro W.; Setiawan, Sonni

    2017-01-01

    Characteristics of atmospheric equatorial Kelvin waves and mixed Rossby-Gravity (MRG) waves as well as their relationship with tropical convective activity associated with El Niño-Southern Oscillation (ENSO) were analyzed. Kelvin waves and MRG waves were identified by using a Space-Time Spectral Analysis (STSA) technique, where the differences in the strength of both waves were quantified by taking the wave spectrum differences for each ENSO phase. Our result showed that Kelvin wave activity is stronger during an El Nino years, whereas the MRG wave activity is stronger during the La Nina years. Seasonal variations of Kelvin wave activity occurs predominantly in MAM over the central to the east Pacific in the El Nino years, while the strongest seasonal variation of MRG wave activity occus in MAM and SON over the northern and southern Pacific during La Nina years. The local variation of Kelvin wave and MRG wave activities are found to be controlled by variation in lower level atmospheric convection induced by sea surface temperature in the tropical Pacific Ocean.

  5. Variational wave-function study of the triangular lattice supersolid.

    PubMed

    Sen, Arnab; Dutt, Prasenjit; Damle, Kedar; Moessner, R

    2008-04-11

    We present a variational wave function which explains the behavior of the supersolid state formed by hard-core bosons on the triangular lattice. The wave function is a linear superposition of only and all configurations minimizing the repulsion between the bosons (which it thus implements as a hard constraint). Its properties can be evaluated exactly--in particular, the variational minimization of the energy yields (i) the surprising and initially controversial spontaneous density deviation from half-filling (ii) a quantitatively accurate estimate of the corresponding density wave (solid) order parameter.

  6. Solitary Waves of the MRLW Equation by Variational Iteration Method

    SciTech Connect

    Hassan, Saleh M.; Alamery, D. G.

    2009-09-09

    In a recent publication, Soliman solved numerically the modified regularized long wave (MRLW) equation by using the variational iteration method (VIM). In this paper, corrected numerical results have been computed, plotted, tabulated, and compared with not only the exact analytical solutions but also the Adomian decomposition method results. Solitary wave solutions of the MRLW equation are exactly obtained as a convergent series with easily computable components. Propagation of single solitary wave, interaction of two and three waves, and also birth of solitons have been discussed. Three invariants of motion have been evaluated to determine the conservation properties of the problem.

  7. Spatial variations in Achilles tendon shear wave speed

    PubMed Central

    DeWall, Ryan J.; Slane, Laura C.; Lee, Kenneth S.; Thelen, Darryl G.

    2014-01-01

    Supersonic shear imaging (SSI) is an ultrasound imaging modality that can provide insight into tissue mechanics by measuring shear wave propagation speed, a property that depends on tissue elasticity. SSI has previously been used to characterize the increase in Achilles tendon shear wave speed that occurs with loading, an effect attributable to the strain-stiffening behavior of the tissue. However, little is known about how shear wave speed varies spatially, which is important, given the anatomical variation that occurs between the calcaneus insertion and the gastrocnemius musculotendon junction. The purpose of this study was to investigate spatial variations in shear wave speed along medial and lateral paths of the Achilles tendon for three different ankle postures: resting ankle angle (R, i.e. neutral), plantarflexed (P; R − 15 deg), and dorsiflexed (D; R + 15 deg). We observed significant spatial and posture variations in tendon shear wave speed in ten healthy young adults. Shear wave speeds in the Achilles free tendon averaged 12 ± 1.2 m/s in a resting position, but decreased to 7.2 ± 1.8 m/s with passive plantarflexion. Distal tendon shear wave speeds often reached the maximum tracking limit (16.3 m/s) of the system when the ankle was in the passively dorsiflexed posture (+15 deg from R). At a fixed posture, shear wave speeds decreased significantly from the free tendon to the gastrocnemius musculotendon junction, with slightly higher speeds measured on the medial side than on the lateral side. Shear wave speeds were only weakly correlated with the thickness and depth of the tendon, suggesting that the distal-to-proximal variations may reflect greater compliance in the aponeurosis relative to the free tendon. The results highlight the importance of considering both limb posture and transducer positioning when using SSI for biomechanical and clinical assessments of the Achilles tendon. PMID:24933528

  8. Seasonal variations of planetary waves simulated by MarsWRF

    NASA Astrophysics Data System (ADS)

    Wang, H.; Toigo, A. D.; Richardson, M. I.

    2010-12-01

    Observations indicate that traveling waves in the Martian atmosphere have distinct seasonality and are greatly influenced by major dust storms. In the northern hemisphere, traveling waves in the first few scale heights appear weakest around the winter solstice period and suppressed following the onset of a major dust storm, and those at higher levels exhibit different behavior. These waves are very important for flushing dust storm development, especially two to three days zonal wave number three waves. We have performed a series numerical simulations using the MarsWRF model to examine the general seasonality and variability of various planetary waves and the effects of major dust storms. The first set of simulations use prescribed dust distributions to represent both the background annual cycle and major dust storms occurring at different time. The model reproduce the seasonal variations of planetary waves well, but the simulated zonal wave number three waves are weaker than the observation. We plan to perform additional simulations with fully interactive dust to test the effect of dust distribution - dynamics feedback on the modeled waves and the development of flushing dust storms.

  9. Variational theory for thermodynamics of thermal waves.

    PubMed

    Sieniutycz, Stanislaw; Berry, R Stephen

    2002-04-01

    We discuss description of macroscopic representations of thermal fields with finite signal speed by composite variational principles involving suitably constructed potentials along with original physical variables. A variational formulation for a given vector field treats all field equations as constraints that are linked by Lagrange multipliers to the given kinetic potential. We focus on the example of simple hyperbolic heat transfer, but also stress that the approach can be easily extended to the coupled transfer of heat, mass, and electric charge. With our approach, various representations may be obtained for physical fields in terms of potentials (gradient or non-gradient representations). Corresponding Lagrangian and Hamiltonian formalism can be developed. Symmetry principles yield components of the energy-momentum tensor for the given kinetic potential. The limiting reversible case appears as a special yet suitable reference frame to describe irreversible phenomena. With the conservation laws resulting from the least action principle and the Gibbs equation, the variational scheme of nonequilibrium thermodynamics follows. Its main property is abandoning the assumption of local thermal equilibrium.

  10. Variational formulation of covariant eikonal theory for vector waves

    SciTech Connect

    Kaufman, A.N.; Ye, H.; Hui, Y.

    1986-10-01

    The eikonal theory of wave propagation is developed by means of a Lorentz-covariant variational principle, involving functions defined on the natural eight-dimensional phase space of rays. The wave field is a four-vector representing the electromagnetic potential, while the medium is represented by an anisotropic, dispersive nonuniform dielectric tensor D/sup ..mu nu../(k,x). The eikonal expansion yields, to lowest order, the Hamiltonian ray equations, which define the Lagrangian manifold k(x), and the wave-action conservation law, which determines the wave-amplitude transport along the rays. The first-order contribution to the variational principle yields a concise expression for the transport of the polarization phase. The symmetry between k-space and x-space allows for a simple implementation of the Maslov transform, which avoids the difficulties of caustic singularities.

  11. Variational formulation of eikonal theory for vector waves

    SciTech Connect

    Kaufman, A.N.; Ye, H.; Hui, Y.

    1986-05-01

    The eikonal theory of wave propagation is developed by means of a Lorentz-covariant variational principle, involving functions defined on the natural eight-dimensional phase space of rays. The wave field is a four-vector representing the electromagnetic potential, while the medium is represented by an anisotropic, dispersive nonuniform dielectric tensor D/sup ..mu.. sup ..nu../(k,x). The eikonal expansion yields, to lowest order, the Hamiltonian ray equations, which define the Lagrangian manifold k(x), and the wave action conservation law, which determines the wave amplitude transport along the rays. The first-order contribution to the variational principle yields a concise expression for the transport of the polarization phase. The symmetry between k-space and x-space allows for a simple implementation of the Maslov transform, which avoids the difficulties of caustic singularities.

  12. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marke, Frank D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    On 26 August 1998, hurricane Bonnie was making landfall near Wilmington, NC. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 2.2 km height documented the sea surface directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

  13. Pulse oximetry in bronchiolitis: is it needed?

    PubMed Central

    Hendaus, Mohamed A; Jomha, Fatima A; Alhammadi, Ahmed H

    2015-01-01

    Infants admitted to health-care centers with acute bronchiolitis are frequently monitored with a pulse oximeter, a noninvasive method commonly used for measuring oxygen saturation. The decision to hospitalize children with bronchiolitis has been largely influenced by pulse oximetry, despite its questionable diagnostic value in delineating the severity of the illness. Many health-care providers lack the appropriate clinical fundamentals and limitations of pulse oximetry. This deficiency in knowledge might have been linked to changes in the management of bronchiolitis. The aim of this paper is to provide the current evidence on the role of pulse oximetry in bronchiolitis. We discuss the history, fundamentals of operation, and limitations of the apparatus. A search of the Google Scholar, Embase, Medline, and PubMed databases was carried out for published articles covering the use of pulse oximetry in bronchiolitis. PMID:26491341

  14. Variations of ULF wave power throughout the Halloween 2003 superstorm

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Balasis, G.; Papadimitriou, C.; Zesta, E.; Georgiou, M.; Mann, I.

    2013-09-01

    Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF waves. We present the overall ULF wave activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometer array in terms of time variations of the ULF wave power. The ULF wave activity is divided upon Pc3 and Pc5 wave power. Thus, we provide different ULF wave activity indices according to the wave frequency (Pc3 and Pc5) and location of observation (Earth's magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF wave activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground.

  15. Variations of ULF wave power throughout the Halloween 2003 superstorm

    NASA Astrophysics Data System (ADS)

    Daglis, I.; Balasis, G.; Papadimitriou, C.; Zesta, E.; Georgiou, M.; Mann, I.

    2013-09-01

    Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF waves. We present the overall ULF wave activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometerer array in terms of time variations of the ULF wave power. The ULF wave activity is divided upon Pc3 and Pc5 wave power. Thus, we provide different ULF wave activity indices according to the wave frequency (Pc3 and Pc5) and location of observation (Earth’s magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF wave activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground. This work has received support from the European Community’s Seventh Framework Programme under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  16. Variations of ULF wave power throughout the Halloween 2003 superstorm

    NASA Astrophysics Data System (ADS)

    Daglis, Ioannis; Balasis, Georgios; Papadimitriou, Constantinos; Zesta, Eftyhia; Georgiou, Marina; Mann, Ian

    2013-04-01

    Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF waves. We present the overall ULF wave activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometerer array in terms of time variations of the ULF wave power. The ULF wave activity is divided upon Pc3 and Pc5 wave power. Thus, we provide different ULF wave activity indices according to the wave frequency (Pc3 and Pc5) and location of observation (Earth's magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF wave activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground. This work has received support from the European Community's Seventh Framework Programme under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  17. The Effect of Area Variation on Wave Rotor Elements

    NASA Technical Reports Server (NTRS)

    Wilson, Jack

    1997-01-01

    The effect of varying the cross-sectional flow area of the passages of a wave rotor is examined by means of the method of characteristics. An idealized expansion wave, an idealized inlet port, and an idealized compression stage are considered. It is found that area variation does not have a very significant effect on the expansion wave, nor on the compression stage. For the expansion wave, increasing the passage area in the flow direction has the same effect as a diffuser, so that the flow emerges at a lower velocity than it would for the constant area case. This could be advantageous. The inlet is strongly affected by the area variation, as it changes the strength of the hammer shock wave, thereby changing the pressure behind it. In this case, reduction in the passage area in the flow direction leads to increased pressure. However, this result is dependent on the assumption that the inlet conditions remain constant with area variation. This may not be the case.

  18. Variation of Short-Scale Waves in the Shoaling Zone

    DTIC Science & Technology

    2001-09-30

    Variation of Short-Scale Waves in the Shoaling Zone Douglas Vandemark NASA/GSFC Laboratory for Hydrospheric Processes Bldg. N-159 Wallops...NASA/GSFC,,Laboratory for Hydrospheric Processes,Bldg. N-159,,Wallops Island,,VA, 23337 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING

  19. Variation of Short-Scale Waves in the Shoaling Zone

    DTIC Science & Technology

    1999-09-30

    Variation of Short-Scale Waves in the Shoaling Zone P.I.: Douglas Vandemark NASA/GSFC Laboratory for Hydrospheric Processes Bldg. N-159 Wallops...Center,Laboratory for Hydrospheric Processes, Bldg. N-159,Wallops Island,VA,23337 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING

  20. Simulating and understanding sand wave variation: A case study of the Golden Gate sand waves

    USGS Publications Warehouse

    Sterlini, F.; Hulscher, S.J.M.H.; Hanes, D.M.

    2009-01-01

    In this paper we present a detailed comparison between measured features of the Golden Gate sand wave field and the results of a nonlinear sand wave model. Because the Golden Gate sand waves exhibit large variation in their characteristics and in their environmental physics, this area gives us the opportunity to study sand wave variation between locations, within one well-measured, large area. The nonlinear model used in this paper is presently the only tool that provides information on the nonlinear evolution of large-amplitude sand waves. The model is used to increase our understanding of the coupling between the variability in environmental conditions and the sand wave characteristics. Results show that the model is able to describe the variation in the Golden Gate sand waves well when both the local oscillating tidal current and the residual current are taken into account. Current and water depth seem to be the most important factors influencing sand wave characteristics. The simulation results give further confidence in the underlying model hypothesis and assumptions. Copyright 2009 by the American Geophysical Union.

  1. Improved variational wave functions for few-body nuclei

    SciTech Connect

    Wiringa, R.B.; Arriaga, A.; Pandharipande, V.R.

    1995-08-01

    We continued to work on improvements to our variational wave functions for use in Monte Carlo calculations of few-body nuclei. These trial functions include central, spin, isospin, tensor, and spin-orbit two-body correlations and three-body correlations for the three-nucleon potential. In the last two years we studied a variety of extra three-body correlations. Our search for possible forms was guided by comparisons made with 34-channel Faddeev wave functions provided by the Los Alamos-Iowa group. The new trial functions reduce the discrepancy with exact Faddeev calculations in {sup 3}H and Green`s Function Monte Carlo (GFMC) calculations in {sup 4}He by about 40%. This work is now being written up for publication. We hope to use similar comparisons with GFMC calculations in the six-body nuclei to find further improvements for the light p-shell nuclei, where the variational wave functions are not as good.

  2. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    On 26 August 1998, the SRA at 2.2 km height documented the directional wave spectrum in the region between Charleston, SC, and Cape Hatteras, NC, as Hurricane Bonnie was making landfall near Wilmington, NC. The storm was similar in size during the two flights, but the maximum speed in the NOAA Hurricane Research Division surface wind analysis was 15% lower prior to landfall (39 m/s) than it had been in the open ocean (46 m/s). This was compensated for by its faster movement prior to landfall (9.5 m/s) than when it was encountered in the open ocean (5 m/s), significantly increasing the effective fetch and duration of waves near the peak of the spectrum which propagated in the direction of the storm track. The open ocean wave height variation indicated that Hurricane Bonnie would have produced waves of 11 m significant wave height on the shore northeast of Wilmington had it not been for the continental shelf. The bathymetry distributed the steepening and breaking process across the shelf so that the wavelength and wave height were reduced gradually as the shore was approached. The wave height 5 km from shore was about 4 in.

  3. Rogue wave variational modelling through the interaction of two solitary waves

    NASA Astrophysics Data System (ADS)

    Gidel, Floriane; Bokhove, Onno

    2016-04-01

    The extreme and unexpected characteristics of Rogue waves have made them legendary for centuries. It is only on the 1st of January 1995 that these mariners' tales started to raise scientist's curiosity, when such a wave was recorded in the North Sea; a sudden wall of water hit the Draupner offshore platform, more than twice higher than the other waves, providing evidence of the existence of rogue or freak waves. Since then, studies have shown that these surface gravity waves of high amplitude (at least twice the height of the other sea waves [Dyste et al., 2008]) appear in non-linear dispersive water motion [Drazin and Johnson, 1989], at any depth, and have caused a lot of damage in recent years [Nikolkina and Didenkulova, 2011 ]. So far, most of the studies have tried to determine their probability of occurrence, but no conclusion has been achieved yet, which means that we are currently unenable to predict or avoid these monster waves. An accurate mathematical and numerical water-wave model would enable simulation and observation of this external forcing on boats and offshore structures and hence reduce their threat. In this work, we aim to model rogue waves through a soliton splash generated by the interaction of two solitons coming from different channels at a specific angle. Kodama indeed showed that one way to produce extreme waves is through the intersection of two solitary waves, or one solitary wave and its oblique reflection on a vertical wall [Yeh, Li and Kodama, 2010 ]. While he modelled Mach reflection from Kadomtsev-Petviashvili (KP) theory, we aim to model rogue waves from the three-dimensional potential flow equations and/or their asymptotic equivalent described by Benney and Luke [Benney and Luke, 1964]. These theories have the advantage to allow wave propagation in several directions, which is not the case with KP equations. The initial solitary waves are generated by removing a sluice gate in each channel. The equations are derived through a

  4. On Variational Methods in the Physics of Plasma Waves

    SciTech Connect

    I.Y. Dodin

    2013-03-08

    A fi rst-principle variational approach to adiabatic collisionless plasma waves is described. The focus is made on one-dimensional electrostatic oscillations, including phase-mixed electron plasma waves (EPW) with trapped particles, such as Bernstein-Greene-Kruskal modes. The well known Whitham's theory is extended by an explicit calculation of the EPW Lagrangian, which is related to the oscillation-center energies of individual particles in a periodic fi eld, and those are found by a quadrature. Some paradigmatic physics of EPW is discussed for illustration purposes. __________________________________________________

  5. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean

    NASA Technical Reports Server (NTRS)

    Wright, C. W.; Walsh, E. J.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.

    1999-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 deg half-power width (two-way) across the aircraft ground track over a swath equal to 0. 8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The data presented were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Wave heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction and at times there were wave fields traveling at right angles to each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 2-minute animation of the directional wave spectrum spatial variation over this period will be shown.

  6. Pulse oximetry: fundamentals and technology update.

    PubMed

    Nitzan, Meir; Romem, Ayal; Koppel, Robert

    2014-01-01

    Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%-4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse

  7. Variational Wave Functions and Their Overlap with the Ground State

    SciTech Connect

    Mora, Christophe; Waintal, Xavier

    2007-07-20

    An intrinsic measure of the quality of a variational wave function is given by its overlap with the ground state of the system. We derive a general formula to compute this overlap when quantum dynamics in imaginary time is accessible. The overlap is simply related to the area under the E({tau}) curve, i.e., the energy as a function of imaginary time. This has important applications to, for example, quantum Monte Carlo simulations where the overlap becomes as a simple by-product of routine simulations. As a result, we find that the practical definition of a good variational wave function for quantum Monte Carlo simulations, i.e., fast convergence to the ground state, is equivalent to a good overlap with the actual ground state of the system.

  8. Minimally invasive optical biopsy for oximetry

    NASA Astrophysics Data System (ADS)

    van der Putten, Marieke A.; Brewer, James M.; Harvey, Andrew R.

    2017-02-01

    The study of localised oxygen saturation in blood vessels can shed light on the etiology and progression of many diseases with which hypoxia is associated. For example, hypoxia in the tendon has been linked to early stages of rheumatoid arthritis, an auto-immune inflammatory disease. Vascular oximetry of deep tissue presents significant challenges as vessels are not optically accessible. In this paper, we present a novel multispectral imaging technique for vascular oximetry, and recent developments made towards its adaptation for minimally invasive imaging. We present proof-of-concept of the system and illumination scheme as well as the analysis technique. We present results of a validation study performed in vivo on mice with acutely inflamed tendons. Adaptation of the technique for minimally invasive microendoscopy is also presented, along with preliminary results of minimally invasive ex vivo vascular oximetry.

  9. Variational modelling of extreme waves through oblique interaction of solitary waves: application to Mach reflection

    NASA Astrophysics Data System (ADS)

    Gidel, Floriane; Bokhove, Onno; Kalogirou, Anna

    2017-01-01

    In this work, we model extreme waves that occur due to Mach reflection through the intersection of two obliquely incident solitary waves. For a given range of incident angles and amplitudes, the Mach stem wave grows linearly in length and amplitude, reaching up to 4 times the amplitude of the incident waves. A variational approach is used to derive the bidirectional Benney-Luke equations, an asymptotic equivalent of the three-dimensional potential-flow equations modelling water waves. This nonlinear and weakly dispersive model has the advantage of allowing wave propagation in two horizontal directions, which is not the case with the unidirectional Kadomtsev-Petviashvili (KP) equation used in most previous studies. A variational Galerkin finite-element method is applied to solve the system numerically in Firedrake with a second-order Störmer-Verlet temporal integration scheme, in order to obtain stable simulations that conserve the overall mass and energy of the system. Using this approach, we are able to get close to the 4-fold amplitude amplification predicted by Miles.

  10. Shear-wave velocity variation in jointed rock: an attempt to measure tide-induced variations

    SciTech Connect

    Beem, L.I.

    1987-08-01

    The use of the perturbation of seismic wave velocities by solid earth tides as a possible method of exploration for fractured media is discussed. Velocity of compressional seismic waves in fractured homogeneous rock has been observed to vary through solid earth tide cycles by a significant 0.5-0.9%. This variation of seismic velocities may be attributed to the opening and closing of joints by tidal stresses. In an attempt to see if shear-wave velocities show a similar velocity variation, a pneumatic shear-wave generator was used for the source. The 5 receivers, 3-component, 2.0 Hz, moving-coil geophones, were connected to a GEOS digital recorder. The two receivers located 120 m and 110 m from the source showed large shear-to-compression amplitude ratio and a high signal-to-noise ratio. A glaciated valley was chosen for the experiment site, since topography is flat and the granodiorite is jointed by a set of nearly orthogonal vertical joints, with superimposed horizontal sheeting joints. A slight velocity variation was noted in the first 200 consecutive firings; after which, the amplitude of the shear-wave begun to increase. This increase has been attributed to the compacting of the soil beneath the shear-wave generator (SWG). In the future, the soil will be compacted prior to placing the SWG or the SWG will be coupled directly to the rock to alleviate the amplitude fluctuation problem. This research may have application in exploration for fracture permeability in the rock mass between existing wells, by measuring seismic velocities from well to well through the tidal cycle.

  11. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Choi, David; Rogers, John H.; Gierasch, Peter J.; Allison, Michael D.; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 S planetographic latitude shows variations in velocity with longitude and time. The presence of the large anticyclonic South Equatorial Disturbance (SED) has a profound effect on the chevron velocity, causing slower velocities to its east and accelerations over distance from the disturbance. The chevrons move with velocities near the maximum wind jet velocity of approx 140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 N latitude. Their repetitive nature is consistent with a gravity-inertia wave (n = 75 to 100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, for the first time, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a 6.7 +/- 0.7-day period. This oscillating motion has a wavelength of approx 20 and a speed of 101 +/- 3 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it. All dates show chevron latitude variability, but it is unclear if this larger wave is present during other epochs, as there are no other suitable time series movies that fully delineate it. In the presence of mUltiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S is likely due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  12. Variational stereo imaging of oceanic waves with statistical constraints.

    PubMed

    Gallego, Guillermo; Yezzi, Anthony; Fedele, Francesco; Benetazzo, Alvise

    2013-11-01

    An image processing observational technique for the stereoscopic reconstruction of the waveform of oceanic sea states is developed. The technique incorporates the enforcement of any given statistical wave law modeling the quasi-Gaussianity of oceanic waves observed in nature. The problem is posed in a variational optimization framework, where the desired waveform is obtained as the minimizer of a cost functional that combines image observations, smoothness priors and a weak statistical constraint. The minimizer is obtained by combining gradient descent and multigrid methods on the necessary optimality equations of the cost functional. Robust photometric error criteria and a spatial intensity compensation model are also developed to improve the performance of the presented image matching strategy. The weak statistical constraint is thoroughly evaluated in combination with other elements presented to reconstruct and enforce constraints on experimental stereo data, demonstrating the improvement in the estimation of the observed ocean surface.

  13. Cerebral Oximetry Use For Cardiac Surgery.

    PubMed

    Raza, Syed Shahmeer; Ullah, Farhan; Chandni; Savage, Edward Bruce

    2017-01-01

    Studies have shown maintaining good cerebral perfusion during Cardiac Surgeries is very important in terms of patient outcomes and reducing the hospital stay, which may have its financial and clinical implications. The aim of this review study was to determine the effectiveness of Cerebral Oximetry (Transcranial Near-Infrared Spectroscopy-NIRS to monitor cerebral oxygenation) for Cardiac Surgery and to propose a possible concluding remark about its potential applications, overall clinical value and whether to keep using it or not. Medical database and archives including Pubmed, Embase, index medicus, index copernicus and Medline were searched. Different papers were looked upon and each had an argument, scientific evidence and background. Fifteen research papers were selected and brought under review after carefully consideration. The papers were carefully reviewed and findings were given in favour of not using NIRS technique for Cerebral Oximetry in Cardiac Surgery. This can rightly be concluded from this study that NIRS Cerebral Oximetry does not carry the clinical significance and relevance which was previously thought. The subject under observation needs further studies and research to evaluate the effectiveness of the Cerebral Oximetry Use for Cardiac Surgery.

  14. Variational structure of inverse problems in wave propagation and vibration

    SciTech Connect

    Berryman, J.G.

    1995-03-01

    Practical algorithms for solving realistic inverse problems may often be viewed as problems in nonlinear programming with the data serving as constraints. Such problems are most easily analyzed when it is possible to segment the solution space into regions that are feasible (satisfying all the known constraints) and infeasible (violating some of the constraints). Then, if the feasible set is convex or at least compact, the solution to the problem will normally lie on the boundary of the feasible set. A nonlinear program may seek the solution by systematically exploring the boundary while satisfying progressively more constraints. Examples of inverse problems in wave propagation (traveltime tomography) and vibration (modal analysis) will be presented to illustrate how the variational structure of these problems may be used to create nonlinear programs using implicit variational constraints.

  15. Pulse oximetry: fundamentals and technology update

    PubMed Central

    Nitzan, Meir; Romem, Ayal; Koppel, Robert

    2014-01-01

    Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse

  16. Assessment of the calibration curve for transmittance pulse-oximetry

    NASA Astrophysics Data System (ADS)

    Doronin, A.; Fine, I.; Meglinski, I.

    2011-11-01

    Optical/laser modalities provide a broad variety of practical solutions for clinical diagnostics and therapy in a range from imaging of single cells and molecules to non-invasive biopsy of specific biological tissues and organs tomography. Near-infrared transmittance pulse oximetry with laser diodes is the accepted standard in current clinical practice and widely used for noninvasive monitoring of oxygen saturation in arterial blood hemoglobin. Conceptual design of practical pulse oximetry systems requires careful selection of various technical parameters, including intensity, wavelength, beam size and profile of incident laser radiation, size, numerical aperture of the detector, as well as a clear understanding of how the spatial and temporal structural alterations in biological tissues can be linked with and can be distinguished by variations of these parameters. In current letter utilizing state-of-the-art NVIDEA CUDA technology, a new object oriented programming paradigm and on-line solutions we introduce a computational tool applied for human finger transmittance spectra simulation and assessment of calibration curve for near-infrared transmitted pulseoximetry.

  17. New spectral imaging techniques for blood oximetry in the retina

    NASA Astrophysics Data System (ADS)

    Alabboud, Ied; Muyo, Gonzalo; Gorman, Alistair; Mordant, David; McNaught, Andrew; Petres, Clement; Petillot, Yvan R.; Harvey, Andrew R.

    2007-07-01

    Hyperspectral imaging of the retina presents a unique opportunity for direct and quantitative mapping of retinal biochemistry - particularly of the vasculature where blood oximetry is enabled by the strong variation of absorption spectra with oxygenation. This is particularly pertinent both to research and to clinical investigation and diagnosis of retinal diseases such as diabetes, glaucoma and age-related macular degeneration. The optimal exploitation of hyperspectral imaging however, presents a set of challenging problems, including; the poorly characterised and controlled optical environment of structures within the retina to be imaged; the erratic motion of the eye ball; and the compounding effects of the optical sensitivity of the retina and the low numerical aperture of the eye. We have developed two spectral imaging techniques to address these issues. We describe first a system in which a liquid crystal tuneable filter is integrated into the illumination system of a conventional fundus camera to enable time-sequential, random access recording of narrow-band spectral images. Image processing techniques are described to eradicate the artefacts that may be introduced by time-sequential imaging. In addition we describe a unique snapshot spectral imaging technique dubbed IRIS that employs polarising interferometry and Wollaston prism beam splitters to simultaneously replicate and spectrally filter images of the retina into multiple spectral bands onto a single detector array. Results of early clinical trials acquired with these two techniques together with a physical model which enables oximetry map are reported.

  18. Planetary Wave Influence on Wintertime OH Meinel Longitudinal Variation?

    NASA Astrophysics Data System (ADS)

    Winick, J. R.; Picard, R. H.; Wintersteiner, P. P.; Mlynczak, M. G.; Russell, J. M.; Gordley, L.

    2009-05-01

    We report on very unusual conditions in the upper mesosphere during the boreal winters of 2004 and 2006. Unusually bright OH volume emissions, as measured by TIMED/SABER, occurred in the region north of 60N. These emissions also occurred at unusually low altitudes, while at the same time very high temperatures characterized the upper mesosphere. These large perturbations allowed us to see more clearly longitudinal spatial and temporal variations that were present in the emissions. The affected areas varied in size and location on time scales of a few days and had a distinct planetary-wave wave-1 structure. We present data demonstrating the variability in the emissions and temperatures throughout the polar region and the correlations among them, and we contrast their behavior with that in normal years. The underlying cause of the correlations and longitudinal structure appears to be greatly enhanced downwelling in the upper mesosphere, which in turn was produced by unusual dynamical conditions in the lower atmosphere, consisting of stratospheric warmings and perturbations of wave structures within the polar vortex.

  19. Does henna impact pulse oximetry results?

    PubMed

    Zolfaghari, Mitra; Moradi Majd, Parisa; Behesht Aeen, Fatemeh; Mohseni, Ali Reza; Azimi Ahangari, Khadijeh; Haghani, Hamid

    2015-03-01

    To evaluate the effects of henna on the results of pulse oximetry in healthy women. 100 young women (20-60 years of age) were recruited. The Iranian original red henna was used to colour the index finger of THE non-dominant hand; the middle finger of the same hand was the control. Blood oxygen saturation was simultaneously measured by two calibrated pulse oximeters. Henna did not affect pulse oximetry measurement of oxygen saturation. There was no statistically significant difference between the control and the henna dyed fingers. Henna is not likely to change the accuracy of oxygen saturation measured by pulse oximeter. 20120906159N20. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  20. Oximetry of retinal capillaries by multicomponent analysis.

    PubMed

    Furukawa, Hiromitsu; Arimoto, Hidenobu; Shirai, Tomohiro; Ooto, Sotaro; Hangai, Masanori; Yoshimura, Nagahisa

    2012-08-01

    Retinal oximetry of capillaries was performed for early detection of retinal vascular abnormalities, which are caused predominantly by complications of systemic circulatory diseases. As the conventional method for determining absorbance is not applicable to capillaries, multicomponent analysis was used to estimate the absorbance spectra of the retinal blood vessels. In this analysis, the capillary spectrum was classified as intermediate between those of the retinal arteries and veins, enabling relative estimation of oxygen saturation in the capillaries. This method could be useful for early recognition of disturbances in the peripheral circulation. Furthermore, a spectroscopic ophthalmoscope system based on the proposed method was developed to examine the human retina. A clinical trial of this system demonstrated that oximetry of the retinal capillaries may be an improvement over the present diagnosis for patients of malignant hypertension.

  1. Retinal vessel oximetry: toward absolute calibration

    NASA Astrophysics Data System (ADS)

    Smith, Matthew H.; Denninghoff, Kurt R.; Lompado, Arthur; Hillman, Lloyd W.

    2000-06-01

    Accurately measuring the oxygen saturation of blood within retinal arteries and veins has proven to be a deceptively difficult task. Despite the excellent optical accessibility of the vessels and a wide range of reported instrumentation, we are unaware of any measurement technique that has proven to be calibrated across wide ranges of vessel diameter and fundus pigmentation. We present an overview of our retinal oximetry technique, present the results of an in vitro calibration experiment, and present preliminary human data.

  2. Variational symplectic particle-in-cell simulation of nonlinear mode conversion from extraordinary waves to Bernstein waves

    SciTech Connect

    Xiao, Jianyuan; Liu, Jian; Qin, Hong; Yu, Zhi; Xiang, Nong

    2015-09-15

    In this paper, the nonlinear mode conversion of extraordinary waves in nonuniform magnetized plasmas is studied using the variational symplectic particle-in-cell simulation. The accuracy of the nonlinear simulation is guaranteed by the long-term accuracy and conservativeness of the symplectic algorithm. The spectra of the electromagnetic wave, the evolution of the wave reflectivity, the energy deposition profile, and the parameter-dependent properties of radio-frequency waves during the nonlinear mode conversion are investigated. It is illustrated that nonlinear effects significantly modify the physics of the radio-frequency injection in magnetized plasmas. The evolutions of the radio-frequency wave reflectivity and the energy deposition are observed, as well as the self-interaction of the Bernstein waves and mode excitations. Even for waves with small magnitude, nonlinear effects can also become important after continuous wave injections, which are common in the realistic radio-frequency wave heating and current drive experiments.

  3. Effect of gravity wave temperature variations on homogeneous ice nucleation

    NASA Astrophysics Data System (ADS)

    Dinh, Tra; Podglajen, Aurélien; Hertzog, Albert; Legras, Bernard; Plougonven, Riwal

    2015-04-01

    Observations of cirrus clouds in the tropical tropopause layer (TTL) have shown various ice number concentrations (INC) (e.g., Jensen et al. 2013), which has lead to a puzzle regarding their formation. In particular, the frequently observed low numbers of ice crystals seemed hard to reconcile with homogeneous nucleation knowing the ubuquity of gravity waves with vertical velocity of the order of 0.1 m/s. Using artificial time series, Spichtinger and Krämer (2013) have illustrated that the variation of vertical velocity during a nucleation event could terminate it and limit the INC. However, their study was limited to constructed temperature time series. Here, we carry out numerical simulations of homogeneous ice nucleation forced by temperature time series data collected by isopycnic balloon flights near the tropical tropopause. The balloons collected data at high frequency (30 s), so gravity wave signals are well resolved in the temperature time series. With the observed temperature time series, the numerical simulations with homogeneous freezing show a full range of ice number concentrations (INC) as previously observed in the tropical upper troposphere. The simulations confirm that the dynamical time scale of temperature variations (as seen from observations) can be shorter than the nucleation time scale. They show the existence of two regimes for homogeneous ice nucleation : one limited by the depletion of water vapor by the nucleated ice crystals (those we name vapor events) and one limited by the reincrease of temperature after its initial decrease (temperature events). Low INC may thus be obtained for temperature events when the gravity wave perturbations produce a non-persistent cooling rate (even with large magnitude) such that the absolute change in temperature remains small during nucleation. This result for temperature events is explained analytically by a dependence of the INC on the absolute drop in temperature (and not on the cooling rate). This

  4. Interannual variation of convectively-coupled equatorial waves and their association with environmental factors

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Chen, Lin

    2016-12-01

    Convectively-coupled equatorial waves (CCEWs) are fundamental components of tropical convection, which are important for weather and climate prediction. However, their interannual variation mechanism has received limited attention to date. By employing 6-hourly satellite-based brightness temperature data from 1983 to 2009, this study investigates the interannual variation of three dominant CCEWs. The results show that the Kelvin wave and the n = 1 westward inertia gravity (WIG) wave display maximum variability over the central Pacific at the equator in boreal winter. Intensity variations in both waves show good correlation relationship with local thermodynamic condition (i.e., sea surface temperature and moisture) and local dynamic condition (i.e., vertically sheared zonal flow). Abundant humidity and weak vertically sheared zonal flow appear in the years of intensified wave activity, whereas less humidity and strong westerly sheared flows appear in the years of suppressed wave activity. Sensitivity numerical experiments show that background moisture are important for both waves, while wind shear can only impact n = 1 WIG wave. A westerly sheared flow tends to suppress the n = 1 WIG wave in the lower troposphere, and thus results in weakened wave growth. n = 1 equatorial Rossby (ER) wave displays maximum variability over the southern Pacific during boreal winter. Its intensity variation is poorly related with local environmental factors but is significantly correlated with El Niño-Southern Oscillation (ENSO) cycle. The results indicate that a different mechanism might be needed to explain the interannual variation of n = 1 ER wave.

  5. The sensitivity of stationary waves to variations in the basic state zonal flow

    NASA Technical Reports Server (NTRS)

    Nigam, Sumant; Lindzen, Richard S.

    1989-01-01

    A linear, primitive equation stationary wave model having high vertical and meridional resolution is used to examine the sensitivity of orographically forced (primarily by Himalayas) stationary waves at middle and high latitudes to variations in the basic state zonal wind distribution. We find relatively little sensitivity to the winds in high latitudes, but remarkable sensitivity to small variations in the subtropical jet. Fluctuations well within the range of observed variability in the jet can lead to large variations in the stationary waves of the high latitude stratosphere, and to large changes even in tropospheric stationary waves. Implications for both sudden warmings and large-scale weather are discussed.

  6. Pulse Oximetry as a Medical Physics Practical on School Trips

    ERIC Educational Resources Information Center

    Gibson, Adam P.; Chandra, Elizabeth; Chandra, Manik

    2009-01-01

    We have measured blood oxygenation levels in a group of 14 people (8 young people and 6 adults) on a physically demanding expedition to Mt Kenya. Blood oxygenation was measured at 11 different altitudes between 1910 and 4985 m using pulse oximetry. We found that pulse oximetry was suitable for use on a youth expedition and we were able to show…

  7. Pulse Oximetry as a Medical Physics Practical on School Trips

    ERIC Educational Resources Information Center

    Gibson, Adam P.; Chandra, Elizabeth; Chandra, Manik

    2009-01-01

    We have measured blood oxygenation levels in a group of 14 people (8 young people and 6 adults) on a physically demanding expedition to Mt Kenya. Blood oxygenation was measured at 11 different altitudes between 1910 and 4985 m using pulse oximetry. We found that pulse oximetry was suitable for use on a youth expedition and we were able to show…

  8. Retinal Oximetry in a Healthy Japanese Population

    PubMed Central

    Nakano, Yuki; Shimazaki, Takeru; Kobayashi, Nobuko; Miyoshi, Yukiko; Ono, Aoi; Kobayashi, Mamoru; Shiragami, Chieko; Hirooka, Kazuyuki; Tsujikawa, Akitaka

    2016-01-01

    Purpose To establish the normative database of retinal oximetry using Oxymap T1 in a healthy Japanese population, and study the reproducibility of the measurements in Japanese. Methods We measured oxygen saturation in the major retinal vessels with Oxymap T1 in 252 eyes of 252 healthy Japanese subjects. Fundus images acquired using Oxymap T1 were processed using built-in Oxymap Analyzer software. Reproducibility of retinal oximetry was investigated using 20 eyes of 20 healthy subjects. Results The mean retinal oxygen saturation of 4 quadrants in healthy Japanese was 97.0 ± 6.9% in arteries and 52.8 ± 8.3% in veins. The mean arteriovenous difference in oxygen saturation was 44.2 ± 9.2%. Both arterial and venous oxygen saturation were significantly lower in the temporal side of the retina, especially in the temporal-inferior vessels. However, the arteriovenous difference in oxygen saturation was limited in the 4 quadrants. Interphotograph, intervisit, and interevaluator intraclass correlation coefficients were 0.936–0.979, 0.809–0.837, and 0.732–0.947, respectively. In the major retinal arteries, oxygen saturation increased with age (r = 0.18, p<0.01), at a rate of 0.67% per 10 years. However, venous oxygen saturation showed no correlation with age. Conclusions This study provides the normative database for the Japanese population. The arterial saturation value appears to be higher than other previous studies. Mean retinal oximetry in 4 quadrants with Oxymap T1 has high reproducibility. PMID:27434373

  9. Variations of total ozone content in the region of mountain lee waves

    NASA Astrophysics Data System (ADS)

    Elanskii, N. F.; Senik, I. A.; Khrgian, A. Kh.

    1988-09-01

    Periodic variations in the total ozone content were detected in the lee side of the Elbrus mountain mass in the Soviet Union in the presence of orographic cloudiness. The period of the variations, and the place and time of their observations are in agreement with the wave pattern of the air flow for this area. It is suggested that the variations in total ozone content are caused by the action of mountain lee waves penetrating the ozone layer in the stratosphere.

  10. Interseasonal Variations in the Middle Atmosphere Forced by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    In our Numerical Spectral Model (NSM), which incorporates Hines' Doppler Spread Parameterization, gravity waves (GW) propagating in the east/west direction can generate the essential features of the observed equatorial oscillations of the zonal circulation and in particular the QBO (quasi-biennial oscillation) extending from the stratosphere into the upper mesosphere. We report here that the NSM also produces inter-seasonal variations in the zonally symmetric meridional circulation. A distinct meridional oscillation (MO) is generated, which appears to be the counterpart to the QBO. With a vertical grid-point resolution of about 0.5 km, the NSM produces the MO through momentum deposition of GW's propagating in the north/south direction. This process is inherently non-linear, of third (odd) order, which enables the oscillation. Since the meridional winds are relatively small compared to the zonal winds, the vertical wavelength required to maintain the MO is also smaller, i.e., only about 10 km instead of the 30 km for the QBO. The corresponding viscous stress is then larger, and the period of the MO is thus short compared with that of the QBO, i.e., only about 3 to 4 months. Depending on the strength of the GW forcing, the computed amplitudes of the meridional wind oscillation are typically 5 m/s in the upper stratosphere and mesosphere, and the associated temperature amplitudes are between about 2 and 3 K. These amplitudes may be observable with the instruments on the TIMED spacecraft. Extended computer simulations with the NSM in 2D and 3D reveal that the MO at low latitudes is modulated by the QBO and in turn can influence it to produce a hemispherically asymmetric component. The annual circulation from the summer to the winter hemisphere is likely to play an important role.

  11. Interseasonal Variations in the Middle Atmosphere Forced by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.; Chan, K. L.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    In our Numerical Spectral Model (NSM), which incorporates Hines' Doppler Spread Parameterization, gravity waves (GW) propagating in the east/west direction can generate the essential features of the observed equatorial oscillations in the zonal circulation and in particular the QBO (quasi-biennial oscillation) extending from the stratosphere into the upper mesosphere. We report here that the NSM also produces inter-seasonal variations in the zonally symmetric (m = 0) meridional circulation. A distinct but variable meridional wind oscillation (MWO) is generated, which appears to be the counterpart to the QBO. With a vertical grid-point resolution of about 0.5 km, the NSM produces the MWO through momentum deposition of GWs propagating in the north/south direction. The resulting momentum source represents a third (generally odd) order non-linear function of the meridional winds, and this enables the oscillation, as in the case of the QBO for the zonal winds. Since the meridional winds are relatively small compared to the zonal winds, however, the vertical wavelength that maintains the MWO is much smaller, i.e., only about 10 km instead of 40 km for the QBO. Consistent with the associated increase of the viscous stress, the period of the MWO is then short compared with that of the QBO, i.e., only about two to four months. Depending on the strength of the GW forcing, the computed amplitudes of the MWO are typically 4 m/s in the upper stratosphere and mesosphere, and the associated temperature amplitudes are between about 2 and 3 K. These amplitudes may be observable with the instruments on the TIMED spacecraft. Extended computer simulations with the NSM in 2D (two-dimensional) and 3D (three-dimensional) reveal that the MWO is modulated by and in turn influences the QBO.

  12. Interseasonal Variations in the Middle Atmosphere Forced by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    In our Numerical Spectral Model (NSM), which incorporates Hines' Doppler Spread Parameterization, gravity waves (GW) propagating in the east/west direction can generate the essential features of the observed equatorial oscillations of the zonal circulation and in particular the QBO (quasi-biennial oscillation) extending from the stratosphere into the upper mesosphere. We report here that the NSM also produces inter-seasonal variations in the zonally symmetric meridional circulation. A distinct meridional oscillation (MO) is generated, which appears to be the counterpart to the QBO. With a vertical grid-point resolution of about 0.5 km, the NSM produces the MO through momentum deposition of GW's propagating in the north/south direction. This process is inherently non-linear, of third (odd) order, which enables the oscillation. Since the meridional winds are relatively small compared to the zonal winds, the vertical wavelength required to maintain the MO is also smaller, i.e., only about 10 km instead of the 30 km for the QBO. The corresponding viscous stress is then larger, and the period of the MO is thus short compared with that of the QBO, i.e., only about 3 to 4 months. Depending on the strength of the GW forcing, the computed amplitudes of the meridional wind oscillation are typically 5 m/s in the upper stratosphere and mesosphere, and the associated temperature amplitudes are between about 2 and 3 K. These amplitudes may be observable with the instruments on the TIMED spacecraft. Extended computer simulations with the NSM in 2D and 3D reveal that the MO at low latitudes is modulated by the QBO and in turn can influence it to produce a hemispherically asymmetric component. The annual circulation from the summer to the winter hemisphere is likely to play an important role.

  13. Review of splanchnic oximetry in clinical medicine

    NASA Astrophysics Data System (ADS)

    Bailey, Sean M.; Mally, Pradeep V.

    2016-09-01

    Global tissue perfusion and oxygenation are important indicators of physiologic function in humans. The monitoring of splanchnic oximetry through the use of near-infrared spectroscopy (NIRS) is an emerging method used to assess tissue oxygenation status. Splanchnic tissue oxygenation (SrS) is thought to be potentially of high value in critically ill patients because gastrointestinal organs can often be the first to suffer ischemic injury. During conditions of hypovolemia, cardiac dysfunction, or decreased oxygen-carrying capacity, blood flow is diverted toward vital organs, such as the brain and the heart at the expense of the splanchnic circulation. While monitoring SrS has great potential benefit, there are limitations to the technology and techniques. SrS has been found to have a relatively high degree of variability that can potentially make it difficult to interpret. In addition, because splanchnic organs only lie near the skin surface in children and infants, and energy from currently available sensors only penetrates a few centimeters deep, it can be difficult to use clinically in a noninvasive manner in adults. Research thus far is showing that splanchnic oximetry holds great promise in the ability to monitor patient oxygenation status and detect disease states in humans, especially in pediatric populations.

  14. Modeling photon transport in transabdominal fetal oximetry

    NASA Astrophysics Data System (ADS)

    Jacques, Steven L.; Ramanujam, Nirmala; Vishnoi, Gargi; Choe, Regine; Chance, Britton

    2000-07-01

    The possibility of optical oximetry of the blood in the fetal brain measured across the maternal abdomen just prior to birth is under investigated. Such measurements could detect fetal distress prior to birth and aid in the clinical decision regarding Cesarean section. This paper uses a perturbation method to model photon transport through a 8- cm-diam fetal brain located at a constant 2.5 cm below a curved maternal abdominal surface with an air/tissue boundary. In the simulation, a near-infrared light source delivers light to the abdomen and a detector is positioned up to 10 cm from the source along the arc of the abdominal surface. The light transport [W/cm2 fluence rate per W incident power] collected at the 10 cm position is Tm equals 2.2 X 10-6 cm-2 if the fetal brain has the same optical properties as the mother and Tf equals 1.0 X 10MIN6 cm-2 for an optically perturbing fetal brain with typical brain optical properties. The perturbation P equals (Tf - Tm)/Tm is -53% due to the fetal brain. The model illustrates the challenge and feasibility of transabdominal oximetry of the fetal brain.

  15. Stationary Planetary Wave and Nonmigrating Tidal Composition of Ionospheric Wave-3 & Wave-4 variations in 2007-2011 FORMOSAT-3/COSMIC observations

    NASA Astrophysics Data System (ADS)

    Chang, L. C.; Lin, C.; Yue, J.; Liu, J. G.; Lin, J.

    2013-12-01

    The wave-3 and wave-4 modulations of the Equatorial Ionization Anomalies (EIAs) are a robust feature of the low latitude ionosphere, when viewed in a constant local time reference frame. Although initially associated respectively with the DE2 and DE3 nonmigrating diurnal tides coupling upwards from the mesosphere and lower thermosphere (MLT) region alone, recent results have suggested that the wave-3 and wave-4 components may also have significant contributions from other nonmigrating tidal and stationary planetary wave (SPW) components. In this study, we present observations of tidal and SPW components comprising the ionospheric wave-3 and wave-4 structures from FORMOSAT-3 / COSMIC Total Electron Content (TEC) from 2007-2011. We find that the wave-3 (wave-4) feature is comprised predominately by DE2 (DE3) and SPW3 (SPW4) throughout the entire five year period, with contributions from SE1 (SE2) being less significant. Additionally, the wave-3 component also has recurring contributions from a DW4 component during December/January. The absolute amplitudes of all the aforementioned components are positively correlated to the level of solar activity, as well as the semiannual variation in zonal mean TEC. After normalizing by the zonal mean TEC, the relative amplitudes of the wave-4 related components show an anti-correlation to solar activity through 2010, which is not seen with the wave-3 related components. The seasonal variation and phase relations of the main constituents of wave-3 and wave-4 are consistent from year to year, as evidenced by the inter-annual recurrence in the peak and trough locations of the ionospheric wave-3 and wave-4. Relative amplitudes of DE3 (black) and SPW4 (blue) in COSMIC TECs as a function of time at 15°N (a) and 15°S (b). Units % of maximum daily zonal mean TEC. Range of uncertainties denoted by dotted lines.

  16. Theory of spin wave modes in tangentially magnetized thin cylindrical dots: A variational approach

    NASA Astrophysics Data System (ADS)

    Zivieri, R.; Stamps, R. L.

    2006-04-01

    We present a theoretical study of the quantized spin wave spectrum in tangentially magnetized cylindrical thin magnetic dots. Low-energy spin waves in magnetic dots may be subdivided into four families: Damon-Eshbach like, backward like, mixed, and end modes. Frequencies and mode profiles are found using a variational approach based on carefully chosen trial functions. The variational method has the advantage that it can be used for large dots that are not practical to treat using numerical finite-element methods. Results for small dots generated using the variational method compare well with micromagnetic results. The variational method is demonstrated with an analysis of data obtained from experimental Brillouin light scattering data from saturated thin cylindrical Permalloy dots. Our approach allows for the definition of parameters describing important contributions to the spin wave energies. As an example, we show that a variational parameter γ provides a measure of spin wave localization near the dot border for one class of modes.

  17. Retinal Oximetry Discovers Novel Biomarkers in Retinal and Brain Diseases.

    PubMed

    Stefánsson, Einar; Olafsdottir, Olof Birna; Einarsdottir, Anna Bryndis; Eliasdottir, Thorunn Scheving; Eysteinsson, Thor; Vehmeijer, Wouter; Vandewalle, Evelien; Bek, Toke; Hardarson, Sveinn Hakon

    2017-05-01

    Biomarkers for several eye and brain diseases are reviewed, where retinal oximetry may help confirm diagnosis or measure severity of disease. These include diabetic retinopathy, central retinal vein occlusion (CRVO), retinitis pigmentosa, glaucoma, and Alzheimer's disease. Retinal oximetry is based on spectrophotometric fundus imaging and measures oxygen saturation in retinal arterioles and venules in a noninvasive, quick, safe manner. Retinal oximetry detects changes in oxygen metabolism, including those that result from ischemia or atrophy. In diabetic retinopathy, venous oxygen saturation increases and arteriovenous difference decreases. Both correlate with diabetic retinopathy severity as conventionally classified on fundus photographs. In CRVO, vein occlusion causes hypoxia, which is measured directly by retinal oximetry to confirm the diagnosis and measure severity. In both diseases, the change in oxygen levels is a consequence of disturbed blood flow with resulting tissue hypoxia and vascular endothelial growth factor (VEGF) production. In atrophic diseases, such as retinitis pigmentosa and glaucoma, retinal oxygen consumption is reduced and this is detected by retinal oximetry. Retinal oximetry correlates with visual field damage and retinal atrophy. It is an objective metabolic measure of the degree of retinal atrophy. Finally, the retina is part of the central nervous system tissue and reflects central nervous system diseases. In Alzheimer's disease, a change in retinal oxygen metabolism has been discovered. Retinal oximetry is a novel, noninvasive technology that opens the field of metabolic imaging of the retina. Biomarkers in metabolic, ischemic, and atrophic diseases of the retina and central nervous system have been discovered.

  18. Transillumination waveform simulator for pulse oximetry

    NASA Astrophysics Data System (ADS)

    Vazquez-Jaccaud, Camille; Paez, Gonzalo; Strojnik, Marija

    2009-08-01

    Pulse oximetry technique is a non invasive method useful to monitor the quantity of oxygen in hemoglobin, used in medical diagnosis and clinical decision-making. It is based on the ratio between the red and infrared light absorbance corresponding to the oxygenated (HbO2) and non-oxygenated (Hb) state of the hemoglobin. We develop the mathematical model to obtain the oxygen saturation value observing that it depends on four known parameters: two transillumination values assessed at the common pulse oximetry wavelengths (λ1 = 660 nm y λ2 = 940 nm), and the extinction coefficients for the oxy- and deoxy-hemoglobin at these given wavelengths. Analyzing the extinction curves for oxy- and deoxy-hemoglobin we note that at λ equal to 660 nm the HbO2 component almost does not contribute to the attenuation of incidance when we transilluminate tissue (7.479x10-5 cm-1M-1). In this case is the Hb component that gives the significant attenuation value (7.863x10-4 cm-1M-1). In 940 nm the extinction coefficient of the Hb is 2.589x10-5 cm-1M-1 and we can ignore it when we count attenuation. At this λ we assume that the pulsate component is only affected by the HbO2 (2.099x10-4 cm-1M-1). This analysis of hemoglobin extinction coefficients in the absorption curves highlights the signal to noise ratio between these two oxygen dependent elements. We are interested in accentuate the better contrast interval (λ pair), where this signal-to-noise ratio is higher, looking for more transillumination information and more precise SO2 value. We propose to use a transillumination waveform simulator to study the different effects (respiration, artifact body movement, absorption, low perfusion, etc) presented in complex physiological signals and to know the optical path-integrated behavior when we transilluminate tissue. This is practical for acquisition and processing transillumination signals. The present work is the first part of a λ selection method to guaratee the optimum S/N for

  19. Four-wavelength retinal vessel oximetry

    NASA Astrophysics Data System (ADS)

    Drewes, Jonathan Jensen

    1999-11-01

    This dissertation documents the design and construction of a four-wavelength retinal vessel oximeter, the Eye Oximeter (EOX). The EOX scans low-powered laser beams (at 629, 678, 821 and 899 nm) into the eye and across a targeted retinal vessel to measure the transmittance of the blood within the vessel. From the transmittance measurements, the oxygen saturation of the blood within the vessel is computed. Retinal vessel oxygen saturation has been suggested as a useful parameter for monitoring a wide range of conditions including occult blood loss and a variety of ophthalmic diseases. An artificial eye that simulates the geometry of a human retinal vessel was constructed and used to calibrate the EOX saturation measurement. A number of different oximetry equations were developed and tested. From measurements made on whole human blood in the artificial eye, an oximetry equation that places a linear wavelength dependance on the scattering losses (3% decrease from 629 to 899 nm) is found to best calibrate the EOX oxygen saturation measurement. This calibration also requires that an adjustment be made to the absorption coefficient of hemoglobin at 629 nm that has been reported in the literature. More than 4,000 measurements were made in the eyes of three human subjects during the development of the EOX. Applying the oximetry equation developed through the in vitro experiments to human data, the average human retinal venous oxygen saturation is estimated to be 0.63 +/- 0.07 and the average human retinal arterial oxygen saturation is 0.99 +/- 0.03. Furthermore, measurements made away from the optic disk resulted in a larger variance in the calculated saturation when compared to measurements made on the optic disk. A series of EOX experiments using anesthetized swine helped to verify the sensitivity of the EOX measurement of oxygen saturation. It is found that the calibration in swine differed from the calibration in the artificial eye. An empirical calibration from the

  20. History of blood gas analysis. VI. Oximetry.

    PubMed

    Severinghaus, J W; Astrup, P B

    1986-10-01

    Oximetry, the measurement of hemoglobin oxygen saturation in either blood or tissue, depends on the Lambert-Beer relationship between light transmission and optical density. Shortly after Bunsen and Kirchhoff invented the spectrometer in 1860, the oxygen transport function of hemoglobin was demonstrated by Stokes and Hoppe-Seyler, who showed color changes produced by aeration of hemoglobin solutions. In 1932 in Göttingen, Germany, Nicolai optically recorded the in vivo oxygen consumption of a hand after circulatory occlusion. Kramer showed that the Lambert-Beer law applied to hemoglobin solutions and approximately to whole blood, and measured saturation by the transmission of red light through unopened arteries. Matthes in Leipzig, Germany, built the first apparatus to measure ear oxygen saturation and introduced a second wavelength (green or infrared) insensitive to saturation to compensate for blood volume and tissue pigments. Millikan built a light-weight ear "oximeter" during World War II to train pilots for military aviation. Wood added a pneumatic cuff to obtain a bloodless zero. Brinkman and Zijlstra in Groningen, The Netherlands, showed that red light reflected from the forehead could be used to measure oxygen saturation. Zijlstra initiated cuvette and catheter reflection oximetry. Instrumentation Laboratory used multiple wavelengths to measure blood carboxyhemoglobin and methemoglobin is cuvette oximeters. Shaw devised an eight-wavelength ear oximeter. Nakajima and co-workers invented the pulse oximeter, which avoids the need for calibration with only two wavelengths by responding only to the pulsatile changes in transmitted red and infrared light. Lübbers developed catheter tip and cuvette fiberoptic sensors for oxygen tension, carbon dioxide tension, and pH.

  1. Percutaneous nocturnal oximetry in amyotrophic lateral sclerosis: periodic desaturation.

    PubMed

    de Carvalho, Mamede; Costa, João; Pinto, Susana; Pinto, Anabela

    2009-06-01

    Percutaneous nocturnal oximetry (PNO) is useful to screen respiratory function in amyotrophic lateral sclerosis (ALS). PNO recordings of some patients disclose a periodical pattern of O(2) desaturation (PP), whose significance is unknown. We aimed to characterize PP pattern, and we used a prospective study enrolling 261 consecutive ALS patients. Clinical, pulmonary and neurophysiological tests performed included: ALS functional rating scale, forced vital capacity (FVC), maximal inspiratory pressure (PImax), mouth occlusion pressure (MOP), phrenic nerve motor response, needle electromyography of the diaphragm, PNO, and sleep study. A total of 837 PNO recordings were analysed (3.2 recordings/patient) and 45 patients showed typical PP (17.2%). Four were excluded, 13 had normal diaphragm (group 1, G1), and in 28 the diaphragm was abnormal (G2). The two groups were comparable, apart from respiratory score, FVC and PImax which were lower in G2. In G1, REM sleep was absent and hypoventilation occurred at slow-wave sleep. Five patients in G1 were very spastic, had low MOP/FVC and a short survival. This study identified a subgroup of ALS patients (G1) with marked signs of upper motor neuron lesion, strong respiratory muscles, PP, low MOP/FVC ratio and poor prognosis. We speculate that they have a central respiratory dysfunction and deserve special care.

  2. Phase Variations of Kilometric Radio Waves Associated with Modification of the Ionosphere by High Power Radio Waves

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.

    2009-12-01

    Quasi-periodic variations in the phase of kilometric radio waves have been detected to occur at the distance of 1000 km from the "Sura" facility emitting high power, high-frequency radio waves. The main feature of the experiment was the appearance of quasi-periodic variations far away from the facility antenna pattern. The amplitudes of phase variations reached 5÷6°,and the variation period was equal to both the duration of stimulation (5 min) and the duration of the interpulse period (5 min). The amplitude of the phase variations was used to estimate the relative amplitude of the electron density disturbance, which reached 10 %. On reference days, the r. m. s. value of the phase variations never exceeded 0.5°, and the relative fluctuations in electron density were equal to 1÷3%.The observed effect cannot be explained by the acoustic-gravity waves generated by the periodic heating of the ionosphere. It most likely involves coupling in the Earth-atmosphere- ionosphere-magnetosphere system.

  3. Pulse oximetry in the diagnosis of acute heart failure.

    PubMed

    Masip, Josep; Gayà, Maria; Páez, Joaquim; Betbesé, Antoni; Vecilla, Francisco; Manresa, Ruben; Ruíz, Pilar

    2012-10-01

    Oxygen saturation by pulse oximetry is commonly used for monitoring critical patients, but its utility as a diagnostic marker of acute heart failure has not been assessed. This study analyzed the diagnostic role of oxygen saturation by pulse oximetry in a series of patients with acute myocardial infarction. In a prospective observational cohort study of 220 consecutive patients with acute myocardial infarction, data collection included baseline oxygen saturation by pulse oximetry (without oxygen), physiologic measurements, Killip class and data from portable chest radiography, recorded at the same hour on each of the first three days after admission. Patients were followed up for one year. There were 612 assessments. Baseline oxygen saturation by pulse oximetry decreased progressively in relation to the presence and the severity of acute heart failure assessed by Killip classes 1 to 3 (mean: 95, 92 and 85, respectively; P<.001) or by Radiology Score 0 to 4 (95, 94, 92, 89 and 83, respectively; P<.001), with a correlation coefficient of 0.66 and 0.63, respectively. Receiver operating characteristic curves disclosed the cut-off of oxygen saturation by pulse oximetry<93 to have the greatest area, with a sensitivity of 65%, specificity 90%, and overall test accuracy 83%. Patients grouped according to lowest oxygen saturation by pulse oximetry showed significantly different rates of one-year mortality or rehospitalization for heart failure. Baseline oxygen saturation by pulse oximetry is useful in establishing the diagnosis and severity of heart failure in acute settings such as myocardial infarction and may have prognostic implications.The diagnosis may be suspected when baseline oxygen saturation by pulse oximetry is <93. Full English text available from:www.revespcardiol.org. Copyright © 2012 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

  4. Variational divergence in wave scattering theory with Kirchhoffean trial functions

    NASA Technical Reports Server (NTRS)

    Bird, J. F.

    1986-01-01

    In a recent study of variational improvement of the Kirchhoff approximation for electromagnetic scattering by rough surfaces, a key ingredient in the variational principle was found to diverge for important configurations (e.g., backscatter) if the polarization had any vertical component. The cause and a cure of this divergence are discussed here. The divergence is demonstrated to occur for arbitrary perfectly conducting scatterers and its universal characterstics are determined, by means of a general divergence criterion that is derived. A variational cure for the divergence is prescribed, and it is tested successfully on a standard scattering model.

  5. The stress-induced surface wave velocity variations in concrete

    NASA Astrophysics Data System (ADS)

    Spalvier, Agustin; Bittner, James; Evani, Sai Kalyan; Popovics, John S.

    2017-02-01

    This investigation studies the behavior of surface wave velocity in concrete specimens subjected to low levels of compressive and tensile stress in beams from applied flexural loads. Beam specimen is loaded in a 4-point-load bending configuration, generating uniaxial compression and tension stress fields at the top and bottom surfaces of the beam, respectively. Surface waves are generated through contactless air-coupled transducers and received through contact accelerometers. Results show a clear distinction in responses from compression and tension zones, where velocity increases in the former and decreases in the latter, with increasing load levels. These trends agree with existing acoustoelastic literature. Surface wave velocity tends to decrease more under tension than it tends to increase under compression, for equal load levels. It is observed that even at low stress levels, surface wave velocity is affected by acoustoelastic effects, coupled with plastic effects (stress-induced damage). The acoustoelastic effect is isolated by means of considering the Kaiser effect and by experimentally mitigating the viscoelastic effects of concrete. Results of this ongoing investigation contribute to the overall knowledge of the acoustoelastic behavior of concrete. Applications of this knowledge may include structural health monitoring of members under flexural loads, improved high order modelling of materials, and validation of results seen in dynamic acoustoelasticity testing.

  6. Effect of basic state on seasonal variation of convectively coupled Rossby wave

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Chen, Lin

    2017-03-01

    Convectively coupled equatorial Rossby (ER) waves display maximum varability over the northern hemisphere during boreal summer and over the southern hemisphere during boreal winter. It suggests that the seasonal variation of ER waves is significantly affected by the annual cycle of basic state. However, which specific environmental factor plays a determining role remains obscure. This study investigates the background influence on the seasonal variation of ER wave by employing an intermediate anomaly atmospheric model. By prescribing boreal summer/winter seasonal mean state as the model's basic state, the authors found that the model is able to simulate the trapping of the ER wave purtrubation over the northern/southern hemisphere as in observation. Further sensitivity experiments suggest that the moisture distribution plays a major role in modulating the ER wave structure while the mosoonal flows play a minor role.

  7. Shadow wave-function variational calculations of crystalline and liquid phases of 4He

    NASA Astrophysics Data System (ADS)

    Vitiello, S. A.; Runge, K. J.; Chester, G. V.; Kalos, M. H.

    1990-07-01

    A new class of variational wave functions for boson systems, shadow wave functions, is used to investigate the properties of solid and liquid 4He. The wave function is translationally invariant and symmetric under particle interchange. In principle, the calculations for the crystalline phase do not require the use of any auxiliary lattice. Using the Metropolis Monte Carlo algorithm, we show that the additional variational degrees of freedom in the wave function lower the energy significantly. This wave function also allows the crystalization of an equilibrated liquid phase when a crystalline seed is used. The pair correlation function and structure factor S(k) are determined in the liquid phase. The condensate fraction is calculated as well. Results are given for the single-particle distribution function around the lattice positions in the solid phase.

  8. Strong lateral variations of S-wave velocity in the upper mantle across the western Alps

    NASA Astrophysics Data System (ADS)

    Lyu, Chao; Pedersen, Helle; Paul, Anne; Zhao, Liang

    2016-04-01

    Absolute S-wave velocity gives more insight into temperature and mineralogy than relative P-wave velocity variations (ΔV p/ V p) imaged by teleseismic traveltime tomography. Moreover, teleseismic P-wave tomography has poor vertical but good horizontal resolution. By contrast, the inversion of surface waves dispersion data gives absolute S-wave velocity with a good vertical but relatively poor horizontal resolution. However, the horizontal resolution of surface wave imaging can be improved by using closely spaced stations in mini-arrays. In this work, we use Rayleigh wave phase velocity dispersion data to measure absolute S-wave velocities beneath the CIFALPS profile across the French-Italian western Alps. We apply the array processing technique proposed by Pedersen et al. (2003) to derive Rayleigh wave phase dispersion curves between 20 s and 100 s period in 15 mini-arrays along the CIFALPS line. We estimate a 1-D S-wave velocity model at depth 50-150 km beneath each mini-array by inverting the dispersion curves jointly with receiver functions. The joint inversion helps separating the crustal and mantle contributions in the inversion of dispersion curves. Distinct lithospheric structures and marked lateral variations are revealed beneath the study region, correlating well with regional geological and tectonic features. The average S-wave velocity from 50 to 150 km depth beneath the CIFALPS area is ˜4.48km/s, almost the same as in model AK135, indicating a normal upper mantle structure in average. Lateral variations are dominated by relatively low velocities (˜4.4km/s) in the mantle of the European plate, very low velocities (4.0km/s, i.e. approximately 12% lower than AK135) beneath the Dora Maira internal crystalline massif and high velocities (˜ 5.0km/s, i.e. 12% higher than AK135) beneath the Po plain. The lateral variations of S-wave velocity perturbation show the same features as the P wave tomography (Zhao et al., submitted), but with different amplitudes

  9. Variation of Pressure Waveforms in Measurements of Extracorporeal Shock Wave Lithotripter

    NASA Astrophysics Data System (ADS)

    Inose, Naoto; Ide, Masao

    1993-05-01

    In this paper, we describe measurement of variation in pressure waveforms of the acoustic field of an extra-corporeal shock-wave lithotripter (ESWL). Variations in the measured acoustic fields and pressure waveform of an underwater spark-gap-type ESWL with an exhausted spark plug electrode have been reported by researchers using crystal sensors. If the ESWL spark plugs become exhausted, patients feel pain during kidney, biliary stone disintegration. We studied the relationship between exhaustion of electrodes and the variation of pressure waveforms and shock-wave fields of the ESWL using a newly developed hydrophone.

  10. The correlation of VLF propagation variations with atmospheric planetary-scale waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Deland, R. J.; Potemra, T. A.; Gavin, R. F.

    1973-01-01

    Variations in the received daytime phase of long distance, cesium-controlled, VLF transmission were compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-region and to variations of f-min which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. These correlations are interpreted as due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed. These correlations provide further evidence for the coupling between the lower ionosphere at about 70 km altitude (the daytime VLF reflection height and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation.

  11. Effect of nonadiabaticity of dust charge variation on dust acoustic waves: generation of dust acoustic shock waves.

    PubMed

    Gupta, M R; Sarkar, S; Ghosh, S; Debnath, M; Khan, M

    2001-04-01

    The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau(ch)/tau(d) has been studied where tau(ch) and tau(d) are the dust charging and dust hydrodynamical time scales on the nonlinear propagation of dust acoustic waves. Analytical investigation shows that the propagation of a small amplitude wave is governed by a Korteweg-de Vries (KdV) Burger equation. Notwithstanding the soliton decay, the "soliton mass" is conserved, but the dissipative term leads to the development of a noise tail. Nonadiabaticity generated dissipative effect causes the generation of a dust acoustic shock wave having oscillatory behavior on the downstream side. Numerical investigations reveal that the propagation of a large amplitude dust acoustic shock wave with dust density enhancement may occur only for Mach numbers lying between a minimum and a maximum value whose dependence on the dusty plasma parameters is presented.

  12. Mesoscale variations in acoustic signals induced by atmospheric gravity waves.

    PubMed

    Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke

    2009-02-01

    The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.

  13. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    NASA Technical Reports Server (NTRS)

    Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent variations in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for variations iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.

  14. Seasonal variations in lower stratospheric gravity wave energy above the Falkland Islands

    NASA Astrophysics Data System (ADS)

    Moffat-Griffin, T.; Jarvis, M. J.; Colwell, S. R.; Kavanagh, A. J.; Manney, G. L.; Daffer, W. H.

    2013-10-01

    gravity wavefield in the lower stratosphere (between 15 km and 22 km altitude) above Mount Pleasant Airport (51°49'S, 58°26'W) on the Falkland Islands is studied using over 2100 high-resolution radiosonde soundings from 2002 to 2010. The seasonal variation in vertical direction of propagation shows a small decrease in numbers of upward propagating waves that is related to critical level filtering; however, there is a very large increase in numbers of downward propagating waves between July and September; this is attributed to the proximity of the edge of the polar vortex. There is a seasonal variation in gravity wave energy density, with a large peak during the austral autumn equinox; this is markedly different to results in the literature both from Rothera, on the Antarctic Peninsula, and stations on the main Antarctic continent. This seasonal pattern has been shown to be linked to variations in the sources of upward propagating gravity waves. The seasonal variation in gravity wave characteristics above Mount Pleasant Airport seen in our results suggests that the gravity wavefield in this region is determined by a combination of different gravity wave sources located above and below the lower stratosphere.

  15. Modulation of whistler mode chorus waves: 2. Role of density variations

    NASA Astrophysics Data System (ADS)

    Li, W.; Bortnik, J.; Thorne, R. M.; Nishimura, Y.; Angelopoulos, V.; Chen, L.

    2011-06-01

    Modulation of whistler mode chorus waves, which plays an important role in driving the pulsating aurora and other processes related to energetic electron dynamics, is an interesting but a long-standing unresolved problem. Here we utilize in situ observations from the THEMIS spacecraft to investigate the role of density variations in the modulation of the chorus wave amplitude, which forms a complementary study to the modulation of chorus by compressional Pc4-5 pulsations presented in a companion paper. We show that these density variations are correlated remarkably well with modulated chorus intensity and typically occur on a timescale of a few seconds to tens of seconds. Both density depletions (DD) and density enhancements (DE) are frequently correlated with increases in chorus wave amplitudes. Furthermore, density enhancements cause a lowering of the central frequencies of the generated chorus waves and vice versa. DD events are more likely to be related to quasi-periodic chorus emissions and thus may be related to the generation of the pulsating aurora. A systematic survey of both DD and DE events shows that DD events preferentially occur between premidnight and dawn, whereas DE events dominantly occur from dawn to noon. We also evaluate the growth rates of chorus waves using linear theory for both DD and DE events and show that both density depletions and enhancements can lead to an intensification of chorus wave growth. However, other potential mechanisms for chorus intensification caused by density variations such as wave trapping by density crests and troughs cannot be excluded.

  16. Examiner's finger-mounted fetal tissue oximetry

    NASA Astrophysics Data System (ADS)

    Kanayama, Naohiro; Niwayama, Masatsugu

    2014-06-01

    The best way to assess fetal condition is to observe the oxygen status of the fetus (as well as to assess the condition of infants, children, and adults). Previously, several fetal oximeters have been developed; however, no instrument has been utilized in clinical practice because of the low-capturing rate of the fetal oxygen saturation. To overcome the problem, we developed a doctor's finger-mounted fetal tissue oximeter, whose sensor volume is one hundredth of the conventional one. Additionally, we prepared transparent gloves. The calculation algorithm of the hemoglobin concentration was derived from the light propagation analysis based on the transport theory. We measured neonatal and fetal oxygen saturation (StO2) with the new tissue oximeter. Neonatal StO was measured at any position of the head regardless of amount of hair. Neonatal StO was found to be around 77%. Fetal StO was detected in every position of the fetal head during labor regardless of the presence of labor pain. Fetal StO without labor pain was around 70% in the first stage of labor and around 60% in the second stage of labor. We concluded that our new concept of fetal tissue oximetry would be useful for detecting fetal StO in any condition of the fetus.

  17. Examiner's finger-mounted fetal tissue oximetry.

    PubMed

    Kanayama, Naohiro; Niwayama, Masatsugu

    2014-06-01

    The best way to assess fetal condition is to observe the oxygen status of the fetus (as well as to assess the condition of infants, children, and adults). Previously, several fetal oximeters have been developed; however, no instrument has been utilized in clinical practice because of the low-capturing rate of the fetal oxygen saturation. To overcome the problem, we developed a doctor's finger-mounted fetal tissue oximeter, whose sensor volume is one hundredth of the conventional one. Additionally, we prepared transparent gloves. The calculation algorithm of the hemoglobin concentration was derived from the light propagation analysis based on the transport theory. We measured neonatal and fetal oxygen saturation (StO₂) with the new tissue oximeter. Neonatal StO₂ was measured at any position of the head regardless of amount of hair. Neonatal StO₂ was found to be around 77%. Fetal StO₂ was detected in every position of the fetal head during labor regardless of the presence of labor pain. Fetal StO₂ without labor pain was around 70% in the first stage of labor and around 60% in the second stage of labor. We concluded that our new concept of fetal tissue oximetry would be useful for detecting fetal StO₂ in any condition of the fetus.

  18. Middle-aged adults exhibit altered spatial variations in Achilles tendon wave speed

    PubMed Central

    Slane, Laura Chernak; DeWall, Ryan; Martin, Jack; Lee, Kenneth; Thelen, Darryl G.

    2016-01-01

    The purpose of this study was to investigate spatial variations in measured wave speed in the relaxed and stretched Achilles tendons of young and middle-aged adults. Wave speed was measured from the distal Achilles tendon, soleus aponeurosis, medial gastrocnemius aponeurosis and medial gastrocnemius muscle in healthy young (n = 15, aged 25 ± 4 years) and middle-aged (n = 10, aged 49 ± 4 years) adults in resting, dorsiflexed and plantarflexed postures. In both age groups, Achilles tendon wave speed decreased proximally, with the lowest wave speed measured in the gastrocnemius aponeurosis. Measured wave speed increased with passive dorsiflexion, reflecting the strain-stiffening behavior of tendons. There were no significant aging effects on wave speed in the free tendon or soleus aponeurosis. However, a significant, inverse relationship between gastrocnemius aponeurosis wave speed and age was observed in the dorsiflexed posture. We also observed significantly lower wave speeds in the gastrocnemius muscles of middle-aged adults when compared with young adults. These results suggest that Achilles tendon compliance increases in a distal-to-proximal pattern, with middle-aged adults exhibiting greater compliance in the distal gastrocnemius muscle and tendinous structures. An age-related change in the spatial variation in Achilles tendon compliance could affect localised tissue deformation patterns and injury potential within the triceps surae muscle-tendon units. PMID:26020294

  19. A phantom with pulsating artificial vessels for non-invasive fetal pulse oximetry.

    PubMed

    Laqua, Daniel; Pollnow, Stefan; Fischer, Jan; Ley, Sebastian; Husar, Peter

    2014-01-01

    Arterial oxygen saturation of the fetus is an important parameter for monitoring its physical condition. During labor and delivery the transabdominal non-invasive fetal pulse oximetry could minimize the risk for mother and fetus, compared to other existing invasive examination methods. In this contribution, we developed a physical-like phantom to investigate new sensor circuits and algorithms of a non-invasive diagnostic method for fetal pulse oximetry. Hence, the developed artificial vascular system consists of two independent tube systems representing the maternal and fetal vessel system. The arterial blood pressure is reproduced with a pre-pressure and an artificial vascular system. Each pulse wave can be reproduced, by digital control of a proportional valve, adjustable viscoelastic elements, and resistances. The measurements are performed by pressure transducers, optical sensor units, and a coplanar capacitive sensor. Transmission and reflection measurements have shown that the fetal and maternal pulse waves can be reproduced qualitatively. The measured light represents the transabdominal modulated signal on an abdomen of a pregnant woman.

  20. Variational principle in optics II: Dissipative wave equations.

    PubMed

    Rubinstein, Jacob; Wolansky, Gershon

    2016-08-01

    The problem of phase retrieval from intensity measurements is examined for the case of dissipative wave equations. Unlike the conservative case, it is not clear if and when the problem is solvable at all. We provide two solutions. First, it is shown that, for a certain class of dissipating potentials, the problem can be fully solved by converting it through a simple transformation to the framework of the weighted least action principle. Second, for all other dissipating potentials, a deep result from the theory of elliptic partial differential equations is used to show that the problem is always solvable up to a scaling of one of the measured intensities. Moreover, the solution in this general case can be obtained by solving a Monge-Ampere type differential equation. Two numerical examples are given to illustrate some of the theoretical considerations.

  1. Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry.

    PubMed

    Chen, Siyu; Yi, Ji; Liu, Wenzhong; Backman, Vadim; Zhang, Hao F

    2015-09-01

    Optical coherence tomography (OCT) oximetry explores the possibility to measure retinal hemoglobin oxygen saturation level (sO2). We investigated the accuracy of OCT retinal oximetry using Monte Carlo simulation in a commonly used four-layer retinal model. After we determined the appropriate number of simulated photon packets, we studied the effects of blood vessel diameter, signal sampling position, physiological sO2 level, and the blood packing factor on the accuracy of sO2 estimation in OCT retinal oximetry. The simulation results showed that a packing factor between 0.2 and 0.4 yields a reasonably accurate estimation of sO2 within a 5% error tolerance, which is independent of vessel diameter and sampling position, when visible-light illumination is used in OCT. We further explored the optimal optical spectral range for OCT retinal oximetry. The simulation results suggest that visible spectral range around 560 nm is better suited than near-infrared spectral range around 800 nm for OCT oximetry to warrant accurate measurements.

  2. Analysis of Wave Propagation in Mechanical Continua Using a New Variational Approach

    NASA Astrophysics Data System (ADS)

    Chakraborty, Goutam

    2017-06-01

    In this paper a new variational principle is presented for studying various wave propagation phenomena without explicitly deriving the equations of motion. The method looks for steady state solutions of linear or non-linear partial differential equations that admit wave-like solutions. Dispersion relations of plane waves propagating in unbounded continuous media, transmission and reflection coefficients of wave incident on the boundary of two semi-infinite media and wave impedance and mobility in an excited medium are studied with the help of the same principle. Numerous examples are given to clarify the method adopted showing distinct advantages over the traditional methods. The scientific insights that this principle provides are also highlighted.

  3. Application of ESR spin label oximetry in food science.

    PubMed

    Zhou, Yu-Ting; Yin, Jun-Jie; Lo, Y Martin

    2011-12-01

    Lipid oxidation attributed to the presence of oxygen has long been a focal area for food science research due in early years mainly to its broad impact on the quality and shelf stability. The need to effectively strategize interventions to detect and eventually eliminate lipid oxidation in food remains as evidence on nutritional and health implications continue to accumulate. Electron spin resonance (ESR) spin label oximetry has been shown capable of detecting dissolved oxygen concentration in both liquid and gaseous phases based on the collision between oxygen and stable free radicals. This review aimed to summarize not just the principles and rationale of ESR spin label oximetry but also the wide spectrum of ESR spin label oximetry applications to date. The feasibility to identify in very early stage oxygen generation and consumption offers a promising tool for controlling lipid oxidation in food and biological systems.

  4. Atomic radiative transition probabilities using negative-energy orbitals in fully variational wave functions

    NASA Astrophysics Data System (ADS)

    Jitrik, Oliverio; Bunge, Carlos F.

    2005-07-01

    Transition probabilities have been computed using a variational many-electron theory [R. Jáuregui, C.F. Bunge, E. Ley-Koo, Phys. Rev. A 55 (1997) 1781] incorporating positive-energy and negative-energy orbitals without ambiguities, and absolutely free from variational collapse. The results agree with experiment and with other calculations based on the no-pair Hamiltonian where ad hoc negative-energy orbitals occur in first-order corrections to the wave functions.

  5. Temporal Variations of Ionospheric Scintillation Index on Cosmic Radiosources Observations at Decametric Wave Range

    NASA Astrophysics Data System (ADS)

    Kravetz, R. O.; Litvinenko, O. A.; Panishko, S. K.

    The measurements of cosmic radiosources have scintillations on ionospheric irregularities at decametric waves. The analysis of temporal variations of the scintillation indexes was carried out on the base of observation data obtained on RT URAN-4 during 1998-2001. Daily-seasonal dependence of these indexes was investigated. The values of scintillation indexes varied within intervals from several minutes to several years, the amplitudes of such variations can reach 70 per cent from mean value.

  6. Fundus spectroscopy and studies in retinal oximetry using intravitreal illumination

    NASA Astrophysics Data System (ADS)

    Salyer, David Alan

    This dissertation documents the development of a new illumination technique for use in the studies of retinal oximetry and fundus spectroscopy. Intravitreal illumination is a technique where the back of the eye is illuminated trans-sclerally using a scanning monochromator coupled into a fiber optic illuminator. Retinal oximetry is the process of measuring the oxygen saturation of blood contained in retinal vessels by quantitative measurement of the characteristic color shift seen as blood oxygen saturation changes from oxygenated blood (reddish) to deoxygenated blood (bluish). Retinal oximetry was first attempted in 1963 but due to a variety of problems with accuracy and difficulty of measurement, has not matured to the point of clinical acceptability or commercial viability. Accurate retinal oximetry relies in part on an adequate understanding of the spectral reflectance characteristics of the fundus. The use of intravitreal illumination allows new investigations into the spectral reflectance properties of the fundus. The results of much research in fundus reflectance and retinal oximetry is detailed in this document, providing new insight into both of these related fields of study. Intravitreal illumination has been used to study retinal vessel oximetry and fundus reflectometry resulting in several important findings that are presented in this document. Studies on enucleated swine eyes have provided new insight into the bidirectional reflectance distribution function of the fundus. Research on live swine has shown accurate measurement of retinal vessel oxygen saturation and provided the first in vivo spectral transmittance measurement of the sensory retina. A secondary discovery during this research suggests that vitrectomy alters the retinal vasculature, an finding that should spawn new research in its own right.

  7. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track

  8. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track

  9. Variation in Population Vulnerability to Heat Wave in Western Australia.

    PubMed

    Xiao, Jianguo; Spicer, Tony; Jian, Le; Yun, Grace Yajuan; Shao, Changying; Nairn, John; Fawcett, Robert J B; Robertson, Andrew; Weeramanthri, Tarun Stephen

    2017-01-01

    Heat waves (HWs) have killed more people in Australia than all other natural hazards combined. Climate change is expected to increase the frequency, duration, and intensity of HWs and leads to a doubling of heat-related deaths over the next 40 years. Despite being a significant public health issue, HWs do not attract the same level of attention from researchers, policy makers, and emergency management agencies compared to other natural hazards. The purpose of the study was to identify risk factors that might lead to population vulnerability to HW in Western Australia (WA). HW vulnerability and resilience among the population of the state of WA were investigated by using time series analysis. The health impacts of HWs were assessed by comparing the associations between hospital emergency department (ED) presentations, hospital admissions and mortality data, and intensities of HW. Risk factors including age, gender, socioeconomic status (SES), remoteness, and geographical locations were examined to determine whether certain population groups were more at risk of adverse health impacts due to extreme heat. We found that hospital admissions due to heat-related conditions and kidney diseases, and overall ED attendances, were sensitive indicators of HW. Children aged 14 years or less and those aged 60 years or over were identified as the most vulnerable populations to HWs as shown in ED attendance data. Females had more ED attendances and hospital admissions due to kidney diseases; while males had more heat-related hospital admissions than females. There were significant dose-response relationships between HW intensity and SES, remoteness, and health service usage. The more disadvantaged and remotely located the population, the higher the health service usage during HWs. Our study also found that some population groups and locations were resilient to extreme heat. We produced a mapping tool, which indicated geographic areas throughout WA with various vulnerability

  10. Variation in Population Vulnerability to Heat Wave in Western Australia

    PubMed Central

    Xiao, Jianguo; Spicer, Tony; Jian, Le; Yun, Grace Yajuan; Shao, Changying; Nairn, John; Fawcett, Robert J. B.; Robertson, Andrew; Weeramanthri, Tarun Stephen

    2017-01-01

    Heat waves (HWs) have killed more people in Australia than all other natural hazards combined. Climate change is expected to increase the frequency, duration, and intensity of HWs and leads to a doubling of heat-related deaths over the next 40 years. Despite being a significant public health issue, HWs do not attract the same level of attention from researchers, policy makers, and emergency management agencies compared to other natural hazards. The purpose of the study was to identify risk factors that might lead to population vulnerability to HW in Western Australia (WA). HW vulnerability and resilience among the population of the state of WA were investigated by using time series analysis. The health impacts of HWs were assessed by comparing the associations between hospital emergency department (ED) presentations, hospital admissions and mortality data, and intensities of HW. Risk factors including age, gender, socioeconomic status (SES), remoteness, and geographical locations were examined to determine whether certain population groups were more at risk of adverse health impacts due to extreme heat. We found that hospital admissions due to heat-related conditions and kidney diseases, and overall ED attendances, were sensitive indicators of HW. Children aged 14 years or less and those aged 60 years or over were identified as the most vulnerable populations to HWs as shown in ED attendance data. Females had more ED attendances and hospital admissions due to kidney diseases; while males had more heat-related hospital admissions than females. There were significant dose–response relationships between HW intensity and SES, remoteness, and health service usage. The more disadvantaged and remotely located the population, the higher the health service usage during HWs. Our study also found that some population groups and locations were resilient to extreme heat. We produced a mapping tool, which indicated geographic areas throughout WA with various

  11. The use of pulse oximetry as a screening assessment for paediatric neurogenic dysphagia.

    PubMed

    Morgan, A T; Omahoney, R; Francis, H

    2008-01-01

    Early screening and intervention for dysphagia is crucial to offset potential outcomes such as compromised nutrition or reduced respiratory function. Current paediatric dysphagia screening tests are subjective with poor sensitivity and specificity. The present study examined whether an objective method, pulse oximetry (measuring oxygen saturation (SpO2) levels), could differentiate between children with and without dysphagia, in relation to (1) Average pre-feeding baseline SpO2 levels; (2) Average feeding SpO2 levels; (3) Average post-feeding SpO2 levels; and (4) The number of events of oxygen desaturation pre-, during and after feeding. Nine participants with chronic neurological disability (CND) (7 F, 2 M) (9; 7-15; 11 years) and nine control participants matched for age (9; 5-16; 0 years) and sex were assessed using a clinical bedside evaluation (CBE) and pulse oximetry. A statistically significant difference was found in SpO2 levels between the two groups (p < 0.001) during oral feeding only (sensitivity, 88.9%; specificity, 88.9%). Only three children with dysphagia experienced 'events' of SpO2 desaturation during feeding. Pulse oximetry may provide a useful adjunct to the CBE for dysphagia screening, with average SpO2 levels during feeding predicting those with and without dysphagia with moderate levels of sensitivity and specificity. The finding of individual variation in desaturation 'events', however, warrants the provision of further data on large homogenous populations to provide definitive criterion for pathological SpO2 levels associated with dysphagia during oral feeding.

  12. Lunar Brightness Variations with Phase at 4.3-MM Wave Length

    NASA Technical Reports Server (NTRS)

    Coates, Robert J.

    1961-01-01

    The lunar radio observations and interpretations of Piddington and Minnett (1949) and Gibson (1958) show that the lunar brightness variation with phase at millimeter wave lengths can be used to determine the physical properties of the lunar surface. They found that the millimeter-wave brightness lagged the optical phase, and their interpretation was that the millimeter radiation originates below a surface layer that is a very good thermal insulator. The thickness of this layer could not be determined from observations at one frequency. Observations at different frequencies give different results because of the wave-length dependence of the radio absorption by the surface material. The attenuation in the material increases with decreasing wave length, and therefore it is possible, in principle, to determine surface layer thickness from radio observations at several wave lengths. For this reason, observations of lunar radiation were started at the Naval Research Laboratory at a wave length of 4.3 mm. This is half the wave length used by Gibson (1958) in his earlier studies. The radio telescope used for these observations has been described in detail in a previous publication (Coates 1958). The antenna is a parabolic reflector 10 feet in diameter, and it has a beam width of 6.7 minutes of arc at the wave length of 4.3 mm. This is about one-fifth the diameter of the moon. The receiver was a Dicke-type radiometer.

  13. Variations in Convectively Coupled Wave Activity and their Relationship with the Background Environment

    NASA Astrophysics Data System (ADS)

    Leroux, S.; Kiladis, G. N.

    2010-12-01

    Different types of convectively coupled equatorial waves are isolated through space-time filtering techniques applied to the NCAR/NCEP Outgoing Long-wave Radiation (OLR) global daily dataset. For each type of wave, a wavelet analysis is applied on the filtered OLR time-series at each grid-point in the Tropics, and the wavelet power is averaged over the range of scale corresponding to the wave type. The resulting daily quantity can be used as an index of the evolution of wave activity with time. The variations of these envelopes of wave activity, and the main time-scales involved, are studied in the context of the waves’ background environment through Empirical Orthogonal Function (EOF) and lag-regression analyses. The evolution of the waves’ envelope of activity onto an index of the Madden Julian Oscillation for the winter and summer seasons suggest that part of the Kelvin wave and Equatorial Rossby (ER) wave activity signals are modulated by MJO phases. Interestingly, the first spatial EOF mode of the Kelvin wave activity envelope does not correspond directly to an MJO signal. This suggests that other modulating factors are likely to be involved. The potential influence of the background flow and of the extra-tropical transient activity in the mid-latitude storm-tracks are also explored. It is found that Pacific Kelvin wave activity is favored during periods of westerly shear with height on the equator in that basin. Strong co-dependence of Kelvin wave activity on the extratropical storm track activity is seen, suggesting that at least some periods of Kelvin activity is excited by extratropical forcing.

  14. Temperature variation effects on sparse representation of guided-waves for damage diagnosis in pipelines

    NASA Astrophysics Data System (ADS)

    Eybpoosh, Matineh; Berges, Mario; Noh, Hae Young

    2015-04-01

    Multiple ultrasonic guided-wave modes propagating along a pipe travel with different velocities which are themselves a function of frequency. Reflections from the features of the structure (e.g., boundaries, pipe welding, damage, etc.), and their complex superposition, adds to the complexity of guided-waves. Guided-wave based damage diagnosis of pipelines becomes even more challenging when environmental and operational conditions (EOCs) vary (e.g., temperature, flow rate, inner pressure, etc.). These complexities make guided-wave based damage diagnosis of operating pipelines a challenging task. This paper reviews the approaches to-date addressing these challenges, and highlights the preferred characteristics of a method that simplifies guided-wave signals for damage diagnosis purposes. A method is proposed to extract a sparse subset of guided-wave signals in time-domain, while retaining optimal damage information for detection purpose. In this paper, the general concept of this method is proved through an extensive set of experiments. Effects of temperature variation on detection performance of the proposed method, and on discriminatory power of the extracted damage-sensitive features are investigated. The potential of the proposed method for real-time damage detection is illustrated, for wide range of temperature variation scenarios (i.e., temperature difference between training and test data varying between -2°C and 13°C).

  15. Effect of Helical Slow-Wave Circuit Variations on TWT Cold-Test Characteristics

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Dayton, James A., Jr.

    1997-01-01

    Recent advances in the state of the art of computer modeling offer the possibility for the first time to evaluate the effect that slow-wave structure parameter variations, such as manufacturing tolerances, have on the cold-test characteristics of helical traveling-wave tubes (TWT's). This will enable manufacturers to determine the cost effectiveness of controlling the dimensions of the component parts of the TWT, which is almost impossible to do experimentally without building a large number of tubes and controlling several parameters simultaneously. The computer code MAFIA is used in this analysis to determine the effect on dispersion and on-axis interaction impedance of several helical slow-wave circuit parameter variations, including thickness and relative dielectric constant of the support rods, tape width, and height of the metallized films deposited on the dielectric rods. Previous computer analyses required so many approximations that accurate determinations of the effect of many relevant dimensions on tube performance were practically impossible.

  16. The influence of temperature variations on ultrasonic guided waves in anisotropic CFRP plates.

    PubMed

    Putkis, O; Dalton, R P; Croxford, A J

    2015-07-01

    Carbon Fibre Reinforced Polymer (CFRP) materials are lightweight and corrosion-resistant and therefore are increasingly used in aerospace, automotive and construction industries. In Structural Health Monitoring (SHM) applications of CFRP materials, ultrasonic guided waves potentially offer large area inspection or inspection from a remote location. This paper addresses the effect of temperature variation on guided wave propagation in highly anisotropic CFRP materials. Temperature variations cause changes in guided wave velocity that can in turn compromise the baseline subtraction procedures employed by many SHM systems for damage detection. A simple model that describes the dependence of elastic properties of the CFRP plates on temperature is presented in this paper. The model can be used to predict anisotropic velocity changes and baseline subtraction performance under varying thermal conditions. The results produced by the model for unidirectional and 0/90 CFRP plates are compared with experimental measurements.

  17. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Murillo, S. T.; Powell, M. D.; Black, P. G.; Marks, F. D.; hide

    2001-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane research aircraft at 1.5 kilometer height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. The data were acquired on 24 August 1998 when Hurricane Bonnie was 400 km east of Abaco Island, Bahamas. Individual waves with heights up to 19 meters were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At one position, three different wave systems of comparable energy and wavelength crossed each other. The aircraft spent over five hours within 180 kilometers of the Hurricane Bonnie eye and made five eye penetrations. On 26 August 1998, the SRA at 2.2 kilometer height documented the directional wave spectrum in the region between Charleston, SC, and Cape Hatteras, NC, as Hurricane Bonnie was making landfall near Wilmington, NC. The storm was similar in size during the two flights, but the maximum speed in the NOAA Hurricane Research Division surface wind analysis was 15% lower prior to landfall (39 meters per second) than it had been in the open ocean (46 meters per second). This was compensated for by its faster movement prior to landfall (9.5 meters per second) than when it was encountered in the open ocean (5 meters per second), significantly increasing the effective fetch and duration of waves near the peak of the spectrum which propagated in the direction of the storm track. The open ocean wave height variation indicated that Hurricane Bonnie would have produced waves of 11 meters significant wave height on the shore northeast of Wilmington had it not been for the continental shelf. The bathymetry distributed the steepening and breaking process across the shelf so that the

  18. Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

    NASA Astrophysics Data System (ADS)

    Humphreys, Kenneth; Ward, Tomas; Markham, Charles

    2007-04-01

    We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16frames/wavelengths, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (SpO2) remotely. Results from an experiment on ten subjects, exhibiting normal SpO2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based "integrative" sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

  19. Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

    SciTech Connect

    Humphreys, Kenneth; Ward, Tomas; Markham, Charles

    2007-04-15

    We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880 nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16 frames/wavelength s, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (S{sub p}O{sub 2}) remotely. Results from an experiment on ten subjects, exhibiting normal S{sub p}O{sub 2} readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based ''integrative'' sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

  20. Regional synchrony of temperature variation and internal wave forcing along the Florida Keys reef tract

    NASA Astrophysics Data System (ADS)

    Leichter, James J.; Stokes, M. Dale; Vilchis, L. Ignacio; Fiechter, Jerome

    2014-01-01

    Analysis of 10 year temperature records collected along the Florida Keys reef tract (FLKRT) reveals strong, regional-scale synchrony in high-frequency temperature variation suggestive of internal wave forcing at predominately semidiurnal frequencies. In each year and at all sites, the amplitude of semidiurnal temperature variation was greatest from March to September, and markedly lower from October to February. Comparisons of the semidiurnal component of the temperature variation among sites suggest complex patterns in the arrival of internal waves, with highest cross correlation among closely spaced sites and synchrony in periods of enhanced internal wave activity across the length of the FLKRT, particularly in summer. The periods of enhanced semidiurnal temperature variation at the 20 and 30 m isobaths on the reef slopes appear to be associated with the dynamics of the Florida Current and the onshore movement of warm fronts preceding the passage of Florida Current frontal eddies. Regional-scale satellite altimetry observations suggest temporal linkages to sea surface height anomalies in the Loop Current (upstream of the Florida Current) and setup of the Tortugas Gyre. The synchronized forcing of cool water onto the reef slope sites across the FLKRT is likely to affect physiological responses to temperature variation in corals and other ectothermic organisms, as well as larval transport and nutrient dynamics with the potential for regionally coherent pulses of larvae and nutrients arriving on reef slopes across the FLKRT.

  1. Numerical study on effects of lateral variations of Moon crustal thickness on lunar seismic wave propagation

    NASA Astrophysics Data System (ADS)

    Chen, F.; Wang, Y.; Jiang, X.

    2016-12-01

    Most recent results reveal drastic lateral variations of crustal thickness around craters on the Moon. Compared with the crust of the earth, the lunar crustal thickness has strong lateral variations, which can vary from as thin as almost zero kilometers to as thick as more than 60 kilometers. However, effects of drastic variations of crustal thickness on lunar seismic wave propagation are still not well understood. In this study we try to reveal how the variance in crustal thickness of the Moon affects the propagation of the lunar seismic waves by numerical simulation. Based on previous research results, we apply a 2-D staggered grid pseudospectral and finite difference hybrid method to perform numerical simulations of seismic wave propagation in a laterally heterogeneous Moon model. We use the newly published layered velocity model as the background model. As indicated by Jiang et al. (2015), scattering by random velocity perturbation in the upper lunar crust plays a fundamental role in lunar seismic wave propagation. Therefore, we consider the random velocity perturbation in upper crust in our model as well. A lateral varying moon crust model is designed, with one side thickness fixed and the other side varying. Stations are deployed at both sides to record lunar seismic waves generated from different kinds of sources, both shallow and deep moonquakes. An average lunar crustal thickness of 35 kilometers is designed as the contrast model. The simulation results demonstrate that the scattering and reverberation of the lunar seismic waves taper off where the crust is comparatively thin but gradually strengthens when the crust gets thick. The propagation of lunar seismic waves generated by shallow moonquakes is more affected by the variations of crustal thickness than that of deep moonquakes. We also conduct simulations based on several recent real lunar crustal profiles and get similar conclusions. This study can enhance our knowledge of lunar seismic wave

  2. Spatial and Temporal Variation of Vorticity Generated by Individual Breaking Waves in the Surfzone

    NASA Astrophysics Data System (ADS)

    Clark, D. B.; Elgar, S.; Raubenheimer, B.

    2012-12-01

    Observations of surfzone vorticity (about a vertical axis) are used to estimate the generation of vorticity by individual breaking waves on an alongshore-uniform beach with directionally spread, normally incident waves. The generated vorticity is O(0.1 s-1) and persists at the location of the observations for 20-60 s after a breaking event. Thus, waves with a mean period of 8 s produce vorticity with the longer timescales associated with cross-shore eddy diffusion. In agreement with theory, vorticity is generated at the ends of a breaking wave crest. However, vorticity generation is also observed in the breaking region 10 to 15 m alongshore of the breaking crest end. We propose that the alongshore growth of the breaking region of a wave as it approaches the shoreline (eg, resulting in the triangular regions of foam shown in Fig. 1) generates vorticity within the breaking crest owing to alongshore variation in the cross-shore integrated breaking force. Funded by a National Security Science and Engineering Faculty Fellowship, The Office of Naval Research, a Woods Hole Oceanographic Institution postdoctoral fellowship, and the National Science Foundation.; Fig. 1. Aerial view of breaking waves. The triangular patches of residual foam are created by the alongshore expansion of the breaking regions of the wave crests as they propagate towards the shoreline on the upper left.

  3. Coherent molecular transistor: Control through variation of the gate wave function

    SciTech Connect

    Ernzerhof, Matthias

    2014-03-21

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

  4. Physiological variation in left atrial transverse orientation does not influence orthogonal P-wave morphology.

    PubMed

    Petersson, Richard; Mosén, Henrik; Steding-Ehrenborg, Katarina; Carlson, Jonas; Faxén, Lisa; Mohtadi, Alan; Platonov, Pyotr G; Holmqvist, Fredrik

    2017-03-01

    It has previously been demonstrated that orthogonal P-wave morphology in healthy athletes does not depend on atrial size, but the possible impact of left atrial orientation on P-wave morphology remains unknown. In this study, we investigated if left atrial transverse orientation affects P-wave morphology in different populations. Forty-seven patients with atrial fibrillation, 21 patients with arrhythmogenic right ventricular cardiomyopathy, 67 healthy athletes, and 56 healthy volunteers were included. All underwent cardiac magnetic resonance imaging or computed tomography and the orientation of the left atrium was determined. All had 12-lead electrocardiographic recordings, which were transformed into orthogonal leads and orthogonal P-wave morphology was obtained. The median left atrial transverse orientation was 87 (83, 91) degrees (lower and upper quartiles) in the total study population. There was no difference in left atrial transverse orientation between individuals with different orthogonal P-wave morphologies. The physiological variation in left atrial orientation was small within as well as between the different populations. There was no difference in left atrial transverse orientation between subjects with type 1 and type 2 P-wave morphology, implying that in this setting the P-wave morphology was more dependent on atrial conduction than orientation. © 2016 Wiley Periodicals, Inc.

  5. Coherent molecular transistor: control through variation of the gate wave function.

    PubMed

    Ernzerhof, Matthias

    2014-03-21

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

  6. Coherent molecular transistor: Control through variation of the gate wave function

    NASA Astrophysics Data System (ADS)

    Ernzerhof, Matthias

    2014-03-01

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

  7. Oximetry considerations in the small source detector separation limit.

    PubMed

    Winey, Brian; Yu, Yan

    2006-01-01

    Oximetry is a common blood monitoring technique, useful for the assessment of blood flow and blood oxygen saturation information. Commercial oximeters generally utilize an optical transmission measurement scenario which necessitates the use of wavelengths residing in the optical absorption window (650-1100 nm) which are capable of traveling long distances before absorption. When the source and detector fibers are brought close together (oximetry techniques and the need to use visible wavelengths when conducting oximetry at small source-detector separations. It will begin with a theoretical derivation of the problems with NIR wavelengths in the small source detector separation limit. The theory will be compared to Monte Carlo derived data and in vivo data collected with a surface probe with oximetry measurements.

  8. Oxygen saturation in pulse oximetry in hemoglobin anomalies.

    PubMed

    Zur, B; Bagci, S; Ludwig, M; Stoffel-Wagner, B

    2012-07-01

    Pulse oximetry is an essential diagnostic method in pediatric emergency medicine and pediatric intensive care. However, if undetected hemoglobin anomalies are the underlying cause measurements of low oxygen saturation can be interpreted incorrectly or may lead to unnecessary examinations. In 2 recently discovered hemoglobin anomalies, Hb Bonn and Hb Venusberg, this resulted in extensive and repeat cardiopulmonary examinations. This review aims to provide an overview of hemoglobin anomalies causing low oxygen saturation.We describe the methods required for differential diagnosis of hemoglobin anomalies, such as hemoglobin electrophoresis, High Performance Liquid Chromatography, hemoglobin gene sequencing and spectral photometry, and the difficulties with the interpretation of results. Furthermore, with a review of the literature we provide an extensive overview of hemoglobin anomalies which result in low oxygen saturation measurement in pulse oximetry. With the examples of Hb Bonn, a novel hemoglobin mutation of the proximal α1-globin, which results in false low pulse oximetry measurements of oxygen saturation, and Hb Venusberg, a low oxygen-affine hemoglobin mutation of the β-globin, we highlight the difficulties arising from the respective case histories.In pediatric medicine, hemoglobin anomalies must be included in the diagnosis as a possible underlying cause of low oxygen saturation in case of ambiguous or conflicting pulse oximetry findings. © Georg Thieme Verlag KG Stuttgart · New York.

  9. Vessel calibre and haemoglobin effects on pulse oximetry.

    PubMed

    McEwen, M P; Bull, G P; Reynolds, K J

    2009-09-01

    Despite its success as a clinical monitoring tool, pulse oximetry may be improved with respect to the need for empirical calibration and the reports of biases in readings associated with peripheral vasoconstriction and haemoglobin concentration. To effect this improvement, this work aims to improve the understanding of the photoplethysmography signal-as used by pulse oximeters-and investigates the effect of vessel calibre and haemoglobin concentration on pulse oximetry. The digital temperature and the transmission of a wide spectrum of light through the fingers of 57 people with known haemoglobin concentrations were measured and simulations of the transmission of that spectrum of light through finger models were performed. Ratios of pulsatile attenuations of light as used in pulse oximetry were dependent upon peripheral temperature and on blood haemoglobin concentration. In addition, both the simulation and in vivo results showed that the pulsatile attenuation of light through fingers was approximately proportional to the absorption coefficients of blood, only when the absorption coefficients were small. These findings were explained in terms of discrete blood vessels acting as barriers to light transmission through tissue. Due to the influence of discrete blood vessels on light transmission, pulse oximeter outputs tend to be dependent upon haemoglobin concentration and on the calibre of pulsing blood vessels-which are affected by vasoconstriction/vasodilation. The effects of discrete blood vessels may account for part of the difference between the Beer-Lambert pulse oximetry model and empirical calibration.

  10. Spatial variations of P wave attenuation in the mantle beneath North America

    NASA Astrophysics Data System (ADS)

    Hwang, Yong Keun; Ritsema, Jeroen; Goes, Saskia

    2009-06-01

    We estimate the spatial variation of the seismic parameter t* using teleseismic (epicentral distance = 30°-85°) P wave spectra of about 200 deep (focal depths > 200 km) earthquakes recorded by 378 broadband seismometers in the United States and Canada. Relative P wave spectral ratios up to 1 Hz for about 63,000 station pairs with high signal-to-noise ratio and impulsive P waveforms are inverted for t*P by least squares inversion. The continental-scale t*P pattern correlates to the age of geological terrains and the seismic, heat flow, gravity, and magnetic variations across North America. Predominantly low values of t*P are obtained in stable central North America (SNA), and high t*P values are obtained for stations in the tectonically active western part of the continent (TNA). This variation is similar to that observed previously in short-period amplitude anomalies, spectral ratio variations, and ScS reverberations. On average, we resolve a contrast in t*P between SNA and TNA of about 0.2 s. We resolve regional variations in t*P, which correlate with tectonics. Relatively low t*P is associated with currently active subduction below Alaska. Relatively high t*P is found in SNA below the Appalachians and the Gulf Coast. The consistency between t*P and tectonics suggests that the observed variations in t*P are, on the scale of around 200-500 km, predominantly due to intrinsic attenuation. The similar patterns in t*P and predicted values for a recent global attenuation model confirm this further. The compatibility with the t*P computed for attenuation estimated via a thermal interpretation of shear wave velocity anomalies illustrates that variations in seismic velocity are predominantly due to physical effects with a strong attenuation signature, most likely temperature or a combination of temperature and water content.

  11. Visualization of oxygen transportation in microcirculation by sidestream dark-field oximetry

    NASA Astrophysics Data System (ADS)

    Kurata, Tomohiro; Takahashi, Minori; Oda, Shigeto; Kawahira, Hiroshi; Ohnishi, Takashi; Haneishi, Hideaki

    2017-02-01

    The sidestream dark-field (SDF) imaging allows direct visualization of red blood cells in microvessels near tissue surfaces. We have developed an image-based oximetry method using two-band images obtained by SDF imaging (SDF oximetry) and a trial SDF device with light-emitting diodes to obtain band images. In this study, we propose a technique of producing oxygen saturation (SO2) maps from SDF images and perform animal experiments in vivo. To produce SO2 maps, we use spectral analysis using two band images obtained with our SDF device. As an image processing, the combination of both the Hessian-based and pixel value-based techniques as blood vessel extraction from an SDF image is used. From the experiment with the surface of rat small intestines, we can produce SO2 maps and find that the map represents arterioles and venules those were determined based on the blood ow from SDF images. Moreover, we find the variation of SO2 along a blood vessel running direction.

  12. Blood gases and oximetry: calibration-free new dry-chemistry and optical technology for near-patient testing.

    PubMed

    Boalth, N; Wandrup, J; Larsson, L; Frischauf, P A; Lundsgaard, F C; Andersen, W L; Jensen, N; Singer, R; Troldborg, C P; Lunding, G

    2001-05-01

    The first calibration-free Near-Patient-Testing instrument (NPT7) for blood gases, pH and oximetry has been developed. With cartridges of 30 single-use cuvettes, the NPT7 needs no preparation prior to sample aspiration, no manual calibration, and no maintenance apart from paper and cartridge changes and regulatory quality control. Each cuvette measures pCO2, pO2, pH, total hemoglobin (ctHb), oxygen saturation (sO2), fractions of carboxyhemoglobin (FCOHb) and methemoglobin (FMetHb) on 95 microl whole blood with a 110-s measuring cycle. The measurement principles are as follows: pCO2-three-wavelength infrared spectroscopy of dissolved CO2; pO2-measurement of O2-induced changes in the decay time of phosphorescence; pH-the absorbance spectra change of an azo-dye color indicator; and oximetry is performed with a 128-wavelength spectrophotometer. We determined the within and between instrument variations with tonometered whole blood on seven prototype instruments, using between one and five control levels per analyte. The 95% analytical performance limits: +/-(/Bias/ +2 xS(T)) in the NPT7 instrument matched the analytical performance criteria for the measured quantities as defined by AACC guidelines. The application of these optical measuring methods for blood gases, pH and oximetry in single-use devices introduces a new concept into point-of-care testing (POCT), where preanalytical activities otherwise associated with instrument preparation are eliminated.

  13. Effects of longshore shelf variations on barotropic continental shelf waves, slope currents and ocean modes

    NASA Astrophysics Data System (ADS)

    Huthnance, J. M.

    Effects of continental shelf bends, converging depth contours and changing depth profiles are discussed. Some analysis is carried out for previously unstudied cases. Separate oceanic interior and shelf flow problems are formulated for a sufficiently narrow shelf. The ocean interior ‘sees’ only an integrated shelf effect, typically increasing shelf-edge amplitudes, retarding longshore Kelvin-wave propagation and increasing natural mode periods by 0 (10%). On the local shelf, the flow matches to the ocean interior and is nondivergent. Effects on shelf waves and slope currents depend subtly on the nature of the longshore variations. Curvature and contour convergence do not per se imply scaterring or generation of shelf waves. Indeed, any depth h(ξ) where ▽ 2ξ(x,y) = 0 (a condition approximating longshelf uniformity in the topography's convexity) supports essentially the same shelf waves as do straight depth contours (DAVIS, 1983), and slope currents follow depth contours. Scattering results rather from breaks in analyticity of the depth profile. Hence calculations for small isolated features (necessarily highly convex or concave) may overestimate scattering, and superposition for realistic topography may lead to much self-cancellation among scattered waves. Otherwise, examples show a strong preference for scattering into adjacent mode numbers and into any shelf wave mode near to its maximum frequency. A shelf sector, where the maximum shelf wave frequency maxω is less than the frequency ω of an incident shelf wave, causes substantial scattering unless maxω and ω are very close. Adjustment of slope currents to changed conditions takes place through (and over the decay distance of) scattered shelf waves.

  14. Seasonal variation in Rayleigh-to-Love wave ratio in the secondary microseism

    NASA Astrophysics Data System (ADS)

    Tanimoto, T.; Hadziioannou, C.; Igel, H.; Wassermann, J. M.; Schreiber, U.; Gebauer, A.; Chow, B.

    2015-12-01

    The Ring Laser (the G-ring) at Wettzell (WET), Germany, is a rotation-measurement instrument that can monitor tiny variations in seismic noise. It essentially records only SH-type signals. Combined with a co-located seismograph (three-component seismograph STS-2), we can monitor the amount of Love waves from this instrument and that of Rayleigh waves from the STS seismograph. We report on seasonal variation of Rayleigh-to-Love wave ratio in the secondary microseism. The first step in our analysis is to obtain stacked Fourier spectra that were least affected by earthquakes. We used two earthquake catalogues to do this; the GCMT (Global Centroid Moment Tensor, Earthquakes M > 5.5) catalogue and the EMSC (European-Mediterranean Seismic Centre) catalogue for regional earthquakes (distance < 1000 km) with M > 4.5. We then created monthly averages of noise Fourier spectra for the frequency range 0.13-0.30 Hz using both the G-ring and STS data from 2009 to 2015. Monthly spectra show clear seasonal variations for the secondary microseism. We obtained surface vertical acceleration from STS and surface transverse acceleration from G-ring from which we can directly measure the Rayleigh-to-Love wave ratio. The procedure is the same with an account in our recent GRL paper (Tanimoto et al., 2015). Comparison between vertical acceleration and transverse acceleration shows that Rayleigh-wave surface amplitudes are about 20 percent larger than Love waves but in terms of kinetic energy this ratio will be different. We converted these ratios of surface amplitude to those of kinetic energy using an available earth model (Fichtner et al., 2013). The averaged ratio over the frequency band 0.13-0.30 Hz shows is in the range 0.6-0.8 in spring, autumn and winter but it increases to about 1.2 in summer. Except for the summer, the amount of Love waves are higher but the amount of Rayleigh waves increases in summer and appears to exceed that of Love waves.

  15. Compositional waves and variations in the atmospheric abundances of magnetic stars

    NASA Astrophysics Data System (ADS)

    Urpin, V.

    2016-02-01

    The stars of the middle main sequence often have relatively quiescent outer layers and spot-like chemical structures may develop in their atmospheres. Recent observations show that abundance peculiarities can change as stars evolve on the main sequence and the timescale of these changes lies in a wide range from million years to months. These observations imply that, perhaps, our understanding of diffusion processes at work in magnetic stars is incomplete and a more detailed analysis of these processes is required. In the present paper, we consider diffusion caused by a combined influence of the electric current and the Hall effect. Such diffusion has a number of very particular properties and, generally, can change the surface chemistry of stars in combination with other diffusion processes. For instant, current-driven diffusion is accompanied by a propagation of the special type of waves in which only the impurity number density oscillates. Propagation of such waves changes the shape and size of spots as well as chemical abundances within them. The period of compositional waves depends on the parameters of plasma (magnetic field, electric current, temperature, etc.) and can be different for the waves of different elements. Compositional waves exist in the regions where the magnetic pressure is greater than the gas pressure. These waves can be the reason of variations with different timescales in the abundance peculiarities of magnetic stars.

  16. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulation

    SciTech Connect

    Ruban, V. P.

    2015-05-15

    The nonlinear dynamics of an obliquely oriented wave packet on a sea surface is analyzed analytically and numerically for various initial parameters of the packet in relation to the problem of the so-called rogue waves. Within the Gaussian variational ansatz applied to the corresponding (1+2)-dimensional hyperbolic nonlinear Schrödinger equation (NLSE), a simplified Lagrangian system of differential equations is derived that describes the evolution of the coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description of the process of nonlinear spatiotemporal focusing, which is one of the most probable mechanisms of rogue wave formation in random wave fields. The system of equations is integrated in quadratures, which allows one to better understand the qualitative differences between linear and nonlinear focusing regimes of a wave packet. Predictions of the Gaussian model are compared with the results of direct numerical simulation of fully nonlinear long-crested waves.

  17. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Ruban, V. P.

    2015-05-01

    The nonlinear dynamics of an obliquely oriented wave packet on a sea surface is analyzed analytically and numerically for various initial parameters of the packet in relation to the problem of the so-called rogue waves. Within the Gaussian variational ansatz applied to the corresponding (1+2)-dimensional hyperbolic nonlinear Schrödinger equation (NLSE), a simplified Lagrangian system of differential equations is derived that describes the evolution of the coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description of the process of nonlinear spatiotemporal focusing, which is one of the most probable mechanisms of rogue wave formation in random wave fields. The system of equations is integrated in quadratures, which allows one to better understand the qualitative differences between linear and nonlinear focusing regimes of a wave packet. Predictions of the Gaussian model are compared with the results of direct numerical simulation of fully nonlinear long-crested waves.

  18. Effects of Spatial Variation of Thermal Electron on Magnetospherically Reflected Whistler Waves Using Ray Tracing

    NASA Astrophysics Data System (ADS)

    Chen, L. J.; Zheng, H. N.; Xiao, F. L.; Wang, S.

    Magnetosphereically reflected whistler waves has been studied by using ray tracing program to investigate their trajectories and amplitude growth or damping The ray tracing program HOTRAY Horne1989 written by Horne is suitable to a hot magnetized plasma containing several electron and ion species with components at different temperatures Therefore the adopted plasma model for HOTRAY have a limitation that temperature of every component is constant throughout space In this paper our concern is how large extent on which the model with temperature variation influences ray path and amplitude of whistler waves propagating in the magnetosphere Here based on the description of HOTRAY in Horne s paper Horne1989 a more capable program is further developed to deal with the adopted plasma model containing three components-- cold electrons and ions Denton2002 and hot anisotropic eletrons Huang1992 The results show that the component of hot electrons effects little on ray path of whistler waves propagation However it changes the growth rate of waves dramatically which is sensitive to the ratio of hot electron density and its anisotropy Denton R E J Goldstein J D Menietti and S L Young 2002 Magnetospheric electron density model inferred from Polar plasma wave data J Geophys Res 107 A11 1386 doi 10 1029 2001JA009136 Horne R B 1989 Path-integrated growth of electronstatic waves the generation of terrestrial myriametric radiation J Geophys Res 94 8895--8909 Huang T S and T J Birmingham 1992 The

  19. Variations in mesospheric gravity waves observed in multiple airglow layers, and filtered temporal spectra studies

    NASA Astrophysics Data System (ADS)

    Mangognia, T.; Swenson, G. R.; Vargas, F.

    2013-12-01

    The Andes Lidar Observatory (ALO) at Cerro Pachon, Chile (Lat= 30.25 S, Long = 70.74 W) is equipped with an all-sky OH and O(1S) airglow imager, OH temperature mapper, OH IR imager, multichannel photometer, meteor radar, and a Na wind/temperature lidar. Spectral analysis of airglow photometry data of OH Meinel (5-1),(6-2); O2 (b) (0,1); and O(1S) emissions reveals varying gravity wave periods over time. Variations in period of high frequency waves are often observed. Studies of frequency variability with the background atmospheric temperature and the effect on the Brunt-Vaisala frequency will be described. Additionally, the vertical separation of the respective layers of a few km offers information regarding wave damping and reflection as the amplitude often changes with altitude. The nature of wave damping is primarily noted to be constant with altitude as a saturated wave spectrum indicates. The correlative nature of the data provides verification of optical methods in characterizing wave attributes. These studies will be described in this presentation.

  20. Spatial and temporal variations of wave energy in the nearshore waters of the central west coast of India

    NASA Astrophysics Data System (ADS)

    Amrutha, M. M.; Sanil Kumar, V.

    2016-12-01

    Assessment of wave power potential at different water depths and time is required for identifying a wave power plant location. This study examines the variation in wave power off the central west coast of India at water depths of 30, 9 and 5 m based on waverider buoy measured wave data. The study shows a significant reduction ( ˜ 10 to 27 %) in wave power at 9 m water depth compared to 30 m and the wave power available at 5 m water depth is 20 to 23 % less than that at 9 m. At 9 m depth, the seasonal mean value of the wave power varied from 1.6 kW m-1 in the post-monsoon period (ONDJ) to 15.2 kW m-1 in the Indian summer monsoon (JJAS) period. During the Indian summer monsoon period, the variation of wave power in a day is up to 32 kW m-1. At 9 m water depth, the mean annual wave power is 6 kW m-1 and interannual variations up to 19.3 % are observed during 2009-2014. High wave energy ( > 20 kW m-1) at the study area is essentially from the directional sector 245-270° and also 75 % of the total annual wave energy is from this narrow directional sector, which is advantageous while aligning the wave energy converter.

  1. Cerebral oximetry as a biomarker of postoperative delirium in cardiac surgery patients.

    PubMed

    Mailhot, Tanya; Cossette, Sylvie; Lambert, Jean; Cournoyer, Alexis; Denault, André Y

    2016-08-01

    A promising monitoring strategy for delirium is the use of cerebral oximetry, but its validity during delirium is unknown. We assessed the relationship between oximetry and delirium. We hypothesized that as cerebral oximetry values increased, delirium would resorb. An observational study was conducted with 30 consecutive adults with delirium after cardiac surgery. Oximetry, delirium assessments, and clinical data were collected for 3 consecutive days after delirium onset. Oximetry was obtained using near-infrared spectroscopy. Delirium was assessed using diagnosis, occurrence (Confusion Assessment Method-ICU), and severity scales (Delirium Index). All patients presented delirium at entry. The mean oximetry value decreased from 66.4±6.7 (mean±SD) to 50.8±6.8 on the first day after delirium onset and increased in patients whose delirium resorbed over the 3 days. The relationship between oximetry, delirium diagnosis, and severity was analyzed with a marginal model and linear mixed models. Cerebral oximetry was related to delirium diagnosis (P≤.0001) and severity (P≤.0001). This study highlighted the links between increased cerebral oximetry values and delirium resorption. Oximetry values may be useful in monitoring delirium progression, thus assisting in the management of this complicated condition. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Variational principle for frozen-in vorticity interacting with sound waves.

    PubMed

    Ruban, V P

    2003-10-01

    General properties of conservative hydrodynamic-type models are treated from positions of the canonical formalism adopted for liquid continuous media. A variational formulation is found for motion and interaction of frozen-in localized vortex structures and acoustic waves in a special description where dynamical variables are, besides the Eulerian fields of the fluid density and the potential component of the canonical momentum, also the shapes of frozen-in lines of the generalized vorticity. This variational principle can serve as a basis for approximate dynamical models with reduced number of degrees of freedom.

  3. Quantum quench in two dimensions using the variational Baeriswyl wave function

    NASA Astrophysics Data System (ADS)

    Dóra, Balázs; Haque, Masudul; Pollmann, Frank; Hetényi, Balázs

    2016-03-01

    By combining the Baeriswyl wave function with equilibrium and time-dependent variational principles, we develop a nonequilibrium formalism to study quantum quenches for two-dimensional spinless fermions with nearest-neighbor hopping and repulsion. The variational ground-state energy, the charge-density wave (CDW) order parameter, and the short-time dynamics agree convincingly with the results of numerically exact simulations. We find that, depending on the initial and final interaction strength, the quenched system either exhibits oscillatory behavior or relaxes to a time-independent steady state. The time-averaged expectation value of the CDW order parameter rises sharply when crossing from the steady-state regime to the oscillating regime, indicating that the system, being nonintegrable, shows signs of thermalization with an effective temperature above or below the equilibrium critical temperature, respectively.

  4. Quantitative ultrasound mapping of regional variations in shear wave speeds of the aging Achilles tendon.

    PubMed

    Slane, Laura Chernak; Martin, Jack; DeWall, Ryan; Thelen, Darryl; Lee, Kenneth

    2017-02-01

    Evaluate the effects of aging on healthy Achilles tendon and aponeurosis shear wave speed (SWS), a quantitative metric which reflects tissue elasticity. Shear wave elastography was used to measure spatial variations in Achilles tendon SWS in healthy young (n = 15, 25 ± 4 years), middle-aged (n = 10, 49 ± 4 years) and older (n = 10, 68 ± 5 years) adults. SWS was separately measured in the free Achilles tendon, soleus aponeurosis and gastrocnemius aponeurosis in resting (R), stretched (dorsiflexed 15° from R) and slack (plantarflexed 15° from R) postures. SWS significantly increased with stretch and varied with age in all tendon regions. Slack free tendon SWS was significantly higher in older adults than young adults (p = 0.025). However, stretched soleus aponeurosis SWS was significantly lower in older adults than young adults (p = 0.01). Stretched gastrocnemius aponeurosis SWS was significantly lower in both middle-aged (p = 0.003) and older (p = 0.001) adults, relative to younger adults. These results suggest that aging alters spatial variations in Achilles tendon elasticity, which could alter deformations within the triceps surae muscle-tendon units, thus affecting injury potential. The observed location- and posture-dependent variations highlight the importance of controlling ankle posture and imaging location when using shear wave approaches clinically to evaluate tendon disorders. • Shear wave elastography shows promise as a clinical quantitative ultrasound-based technique. • Aging induces location-dependent changes in Achilles tendon shear wave speed. • Spatial and postural dependence necessitates careful integration of this approach clinically.

  5. Quantifying the effect of adipose tissue in muscle oximetry by near infrared spectroscopy

    PubMed Central

    Nasseri, Nassim; Kleiser, Stefan; Ostojic, Daniel; Karen, Tanja; Wolf, Martin

    2016-01-01

    Change of muscle tissue oxygen saturation (StO2), due to exercise, measured by near infrared spectroscopy (NIRS) is known to be lower for subjects with higher adipose tissue thickness. This is most likely not physiological but caused by the superficial fat and adipose tissue. In this paper we assessed, in vitro, the influence of adipose tissue thickness on muscle StO2, measured by NIRS oximeters. We measured StO2 of a liquid phantom by 3 continuous wave (CW) oximeters (Sensmart Model X-100 Universal Oximetry System, INVOS 5100C, and OxyPrem v1.3), as well as a frequency-domain oximeter, OxiplexTS, through superficial layers with 4 different thicknesses. Later, we employed the results to calibrate OxyPrem v1.3 for adipose tissue thickness in-vivo. PMID:27895999

  6. Velocity variations and uncertainty from transdimensional P-wave tomography of North America

    NASA Astrophysics Data System (ADS)

    Burdick, Scott; Lekić, Vedran

    2017-03-01

    High-resolution models of seismic velocity variations constructed using body-wave tomography inform the study of the origin, fate, and thermochemical state of mantle domains. In order to reliably relate these variations to material properties including temperature, composition, and volatile content, we must accurately retrieve both the patterns and amplitudes of variations and quantify the uncertainty associated with the estimates of each. For these reasons, we image the mantle beneath North America with P-wave traveltimes from USArray using a novel method for 3-D probabilistic body-wave tomography. The method uses a Transdimensional Hierarchical Bayesian (THB) framework with a reversible-jump Markov Chain Monte Carlo (rj-MCMC) algorithm in order to generate an ensemble of possible velocity models. We analyze this ensemble solution to obtain the posterior probability distribution of velocities, thereby yielding error bars and enabling rigorous hypothesis testing. Overall, we determine that the average uncertainty (1σ) of compressional wave velocity estimates beneath North America is ∼0.25% dVP/VP, increasing with proximity to complex structure and decreasing with depth. The addition of USArray data reduces the uncertainty beneath the Eastern US by over 50% in the upper mantle and 25-40% below the transition zone and ∼30% throughout the mantle beneath the Western US. In the absence of damping and smoothing, we recover amplitudes of variations 10-80% higher than a standard inversion approach. Accounting for differences in data coverage, we infer that the length-scale of heterogeneity is ∼50% longer at shallow depths beneath the continental platform than beneath tectonically active regions. We illustrate the model trade-off analysis for the Cascadia slab and the New Madrid Seismic Zone, where we find that smearing due to the limitations of the illumination is relatively minor.

  7. Data fusion for compensation of temperature variations in Lamb-wave based SHM systems

    NASA Astrophysics Data System (ADS)

    Dworakowski, Ziemowit; Ambrozinski, Lukasz; Stepinski, Tadeusz

    2015-03-01

    Temperature variations affect Lamb wave propagation and therefore in this way they can severely limit application of baseline signals in SHM systems. Various techniques are proposed in the paper to solve this problem. New method based on an interpretation of multiple signals acquired in distinct points of the structure is introduced and compared with other widely used approaches. Data fusion is used to merge a number of methods into one with a substantially increased efficiency.

  8. Velocity variations and uncertainty from transdimensional P-wave tomography of North America

    NASA Astrophysics Data System (ADS)

    Burdick, Scott; Lekić, Vedran

    2017-05-01

    High-resolution models of seismic velocity variations constructed using body-wave tomography inform the study of the origin, fate and thermochemical state of mantle domains. In order to reliably relate these variations to material properties including temperature, composition and volatile content, we must accurately retrieve both the patterns and amplitudes of variations and quantify the uncertainty associated with the estimates of each. For these reasons, we image the mantle beneath North America with P-wave traveltimes from USArray using a novel method for 3-D probabilistic body-wave tomography. The method uses a Transdimensional Hierarchical Bayesian framework with a reversible-jump Markov Chain Monte Carlo algorithm in order to generate an ensemble of possible velocity models. We analyse this ensemble solution to obtain the posterior probability distribution of velocities, thereby yielding error bars and enabling rigorous hypothesis testing. Overall, we determine that the average uncertainty (1σ) of compressional wave velocity estimates beneath North America is ˜0.25 per cent dVP/VP, increasing with proximity to complex structure and decreasing with depth. The addition of USArray data reduces the uncertainty beneath the Eastern US by over 50 per cent in the upper mantle and 25-40 per cent below the transition zone and ˜30 per cent throughout the mantle beneath the Western US. In the absence of damping and smoothing, we recover amplitudes of variations 10-80 per cent higher than a standard inversion approach. Accounting for differences in data coverage, we infer that the length scale of heterogeneity is ˜50 per cent longer at shallow depths beneath the continental platform than beneath tectonically active regions. We illustrate the model trade-off analysis for the Cascadia slab and the New Madrid Seismic Zone, where we find that smearing due to the limitations of the illumination is relatively minor.

  9. The detection of T-wave variation linked to arrhythmic risk: an industry perspective.

    PubMed

    Xue, Joel; Rowlandson, Ian

    2013-01-01

    Although the scientific literature contains ample descriptions of peculiar patterns of repolarization linked to arrhythmic risk, the objective quantification and classification of these patterns continues to be a challenge that impacts their widespread adoption in clinical practice. To advance the science, computerized algorithms spawned in the academic environment have been essential in order to find, extract and measure these patterns. However, outside the strict control of a core lab, these algorithms are exposed to poor quality signals and need to be effective in the presence of different forms of noise that can either obscure or mimic the T-wave variation (TWV) of interest. To provide a practical solution that can be verified and validated for the market, important tradeoffs need to be made that are based on an intimate understanding of the end-user as well as the key characteristics of either the signal or the noise that can be used by the signal processing engineer to best differentiate them. To illustrate this, two contemporary medical devices used for quantifying T-wave variation are presented, including the modified moving average (MMA) for the detection of T-wave Alternans (TWA) and the quantification of T-wave shape as inputs to the Morphology Combination Score (MCS) for the trending of drug-induced repolarization abnormalities. © 2013 Elsevier Inc. All rights reserved.

  10. Seasonal variation of mesospheric waves at northern middle and high latitudes

    NASA Astrophysics Data System (ADS)

    Hoffmann, Peter; Becker, Erich; Singer, Werner; Placke, Manja

    2010-09-01

    The seasonal variation of the wave activity in the mesosphere/lower thermosphere is investigated using wind measurements with meteor and MF radars at Juliusruh (55°N, 13°E) and Andenes (69°N, 16°E), as well as on the basis of the simulated annual cycle using a gravity-wave resolving mechanistic general circulation model. For the observations, proxies for the activity of gravity waves (GWs) and waves with longer periods are computed from wind variances for defined bandwidths. Our corresponding proxy for the simulated GWs is the non-rotational kinetic energy due to the resolved mesoscales. Both observational and computational results show the strongest GW energy during winter and a secondary maximum during summer. Additional observational analysis of short-period GWs yields a more pronounced summer maximum. The semi-annual variation is consistent with the selective filtering of westward and eastward GWs by the mean zonal wind. The latitudinal dependence during summer is characterized by stronger GW energy between 65 and 85 km at middle latitudes than at polar latitudes, and a corresponding upward shift of the wind reversal towards the pole which is also reflected by the simulated GW drag. Also the observed oscillations with periods from 2 to 4 days show a latitudinal dependence and a clear seasonal cycle which is related to the mean zonal wind shear.

  11. Matter-Wave Fields for Double-Slit Atom Interferometry: Variational Versus Exact Solitons

    NASA Astrophysics Data System (ADS)

    Ndifon Ngek, Isaiah; Moïse Dikandé, Alain; Moubissi, Alain Brice

    2016-12-01

    A major challenge in the theoretical modeling of double-slit interferometry involving matter-wave fields is the appropriate waveform to be assigned to this field. While all the studies carried out to date on this issue deal with variational fields, experiments suggest that the optical field is generated by splitting a single-hump Bose-Einstein condensate into two spatially and temporally entangled pulses indicating the possibility of fully controlling the subsequent motion of the two output pulses. To probe the consistency of variational and exact soliton solutions to the field equation, we solve the Gross-Pitaevskii equation with an optical potential barrier assumed to act as a beam splitter, while including gravity. The exact solution is compared with the two most common variational wavefunctions, namely, the Hermite-Gaussian and super-sech modes. From numerical simulations, evidence is given of the exact solution as being the most appropriate matter-wave structure that provides a coherent description of the generation and spatio-temporal evolution of matter-wave optical fields in a hypothetical implementation of double-slit atom interferometry.

  12. Coda wave interferometry for the measurement of thermally induced ultrasonic velocity variations in CFRP laminates

    NASA Astrophysics Data System (ADS)

    Livings, Richard; Dayal, Vinay; Barnard, Dan

    2016-02-01

    Ultrasonic velocity measurement is a well-established method to measure properties and estimate strength as well as detect and locate damage. Determination of accurate and repeatable ultrasonic wave velocities can be difficult due to the influence of environmental and experimental factors. Diffuse fields created by a multiple scattering environment have been shown to be sensitive to homogeneous strain fields such as those caused by temperature variations, and Coda Wave Interferometry has been used to measure the thermally induced ultrasonic velocity variation in concrete, aluminum, and the Earth's crust. In this work, we analyzed the influence of several parameters of the experimental configuration on the measurement of thermally induced ultrasonic velocity variations in a carbon-fiber reinforced polymer plate. Coda Wave Interferometry was used to determine the relative velocity change between a baseline signal taken at room temperature and the signal taken at various temperatures. The influence of several parameters of the experimental configuration, such as the material type, the receiver aperture size, and fiber orientation on the results of the processing algorithm was evaluated in order to determine the optimal experimental configuration.---This work is supported by the NSF Industry/University Cooperative Research Program of the Center for Nondestructive Evaluation at Iowa State University.

  13. Climate variability of heat waves and their associated diurnal temperature range variations in Taiwan

    NASA Astrophysics Data System (ADS)

    Kueh, M.-T.; Lin, C.-Y.; Chuang, Y.-J.; Sheng, Y.-F.; Chien, Y.-Y.

    2017-07-01

    This study investigates heat waves in Taiwan and their maintenance mechanism, based upon observations and dynamically downscaled simulations. A 95th percentile threshold is used for identifying hot extremes over a period of consecutive days. Heat waves are forecast to become more severe in the future projection. Daily minimum temperatures are generally high and diurnal temperature ranges (DTR) are relatively large. The daily minimum temperature serves as the primary control in the variation in DTR during heat waves. An apparent increase in the daily minimum temperature suggests elevated heat stress at nighttime during future heat waves. Heat waves in Taiwan are associated with abnormal warming and drying atmospheric conditions under the control of an enhanced western North Pacific subtropical high. The surrounding waters serve as a vast moisture source to suppress the drying magnitude in the surface layer as the temperature rises, thereby ensuring a high humidity level during the hot spell. The subsidence and adiabatic warming above can trap the warm and humid air in the surface layer, leading to positive feedback to the abnormally hot surface condition. The associated warming and drying atmospheric conditions cover certain spatial extents, suggesting that the extreme situation identified here is not confined to just an island-wide hot spell; the abnormal hot weather can take place across a broad geographical area.

  14. A 4D variational assimilation scheme with partition method for nearshore wave models

    NASA Astrophysics Data System (ADS)

    Song, Qingyang; Mayerle, Roberto

    2017-08-01

    This paper summarizes the development steps of a 4D variational assimilation scheme for nearshore wave models. A partition method is applied for adjusting both wave boundary conditions and wind fields. Nonstationary conditions are assimilated by providing defined correlations of model inputs in time. The scheme is implemented into the SWAN model. Twin experiments covering both stationary and nonstationary wave conditions are carried out to assess the adequacy of the proposed scheme. Stationary experiments are carried out considering separately windsea, swells, and mixed sea. Cost functions decline to less than 5% and RMS spectrum errors are reduced to less than 10%. The nonstationary experiment covers 1 day simulation under mixed wave conditions with assimilation windows of 3 h. RMS spectrum errors are reduced to less than 10% after 30 iterations in most assimilation windows. The results show that for spacially uniform model inputs, model accuracy is improved notably by the assimilation scheme throughout the computational domain. It is found that under wave conditions in which observed spectra can be well classified, the assimilation scheme is able to improve model results significantly.

  15. Spatial variations of ocean wave directional spectra from the Seasat synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Beal, R. C.; Gerling, T. W.; Irvine, D. E.; Monaldo, F. M.; Tilley, D. G.

    1986-01-01

    Seasat synthetic aperture radar ocean wave spectra for a 900-km pass are analyzed and interpreted in the context of both their probable generation sources and their surface current and bathymetric modifiers. Systematic vector wavenumber variations of several times the standard error of determination (about 1.5 percent in magnitude and 0.9 deg in direction) occur along the entire 900-km pass. The large-scale spatial variation of a 200-m swell system can be accurately accounted for as a result of dispersion from a distant storm. The more local variations are qualitatively well correlated in position with known currents and bathymetry but show systematic biases that appear partly due to an environmentally dependent instrument transfer function in the regions of high current and highest sea state. There is also substantial evidence that a large angular deviation in the center of the pass is the result of a mesoscale eddy just to the east.

  16. LED power reduction trade-offs for ambulatory pulse oximetry.

    PubMed

    Peláez, Eduardo Aguilar; Villegas, Esther Rodríguez

    2007-01-01

    The development of ambulatory arterial pulse oximetry is key to longer term monitoring and treatment of cardiovascular and respiratory conditions. The investigation presented in this paper will assist the designer of an ambulatory pulse oximetry monitor in minimizing the overall LED power consumption (P LED,TOT) levels by analyzing the lowest achievable limit as constrained by the optical components, circuitry implementation and final SpO2 reading accuracy required. LED duty cycle (D LED) reduction and light power (P LED,ON) minimization are proposed as methods to reduce P LED,TOT. Bandwidth and signal quality calculations are carried out in order to determine the required P LED,TOT as a function of the different noise sources.

  17. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marks, Frank D.

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights

  18. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marks, Frank D.

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights

  19. Hamiltonians and variational principles for Alfvén simple waves

    NASA Astrophysics Data System (ADS)

    Webb, G. M.; Hu, Q.; le Roux, J. A.; Dasgupta, B.; Zank, G. P.

    2012-01-01

    The evolution equations for the magnetic field induction B with the wave phase for Alfvén simple waves are expressed as variational principles and in the Hamiltonian form. The evolution of B with the phase (which is a function of the space and time variables) depends on the generalized Frenet-Serret equations, in which the wave normal n (which is a function of the phase) is taken to be tangent to a curve X, in a 3D Cartesian geometry vector space. The physical variables (the gas density, fluid velocity, gas pressure and magnetic field induction) in the wave depend only on the phase. Three approaches are developed. One approach exploits the fact that the Frenet equations may be written as a 3D Hamiltonian system, which can be described using the Nambu bracket. It is shown that B as a function of the phase satisfies a modified version of the Frenet equations, and hence the magnetic field evolution equations can be expressed in the Hamiltonian form. A second approach develops an Euler-Poincaré variational formulation. A third approach uses the Frenet frame formulation, in which the hodograph of B moves on a sphere of constant radius and uses a stereographic projection transformation due to Darboux. The equations for the projected field components reduce to a complex Riccati equation. By using a Cole-Hopf transformation, the Riccati equation reduces to a linear second order differential equation for the new variable. A Hamiltonian formulation of the second order differential equation then allows the system to be written in the Hamiltonian form. Alignment dynamics equations for Alfvén simple waves give rise to a complex Riccati equation or, equivalently, to a quaternionic Riccati equation, which can be mapped onto the Riccati equation obtained by stereographic projection.

  20. Can the Tibetan Plateau snow cover influence the interannual variations of Eurasian heat wave frequency?

    NASA Astrophysics Data System (ADS)

    Wu, Zhiwei; Zhang, Peng; Chen, Hua; Li, Yun

    2016-06-01

    The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30 % of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land-atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades.

  1. Can the Tibetan Plateau Snow Cover Influence the Interannual Variations of Eurasian Heat Wave Frequency?

    NASA Astrophysics Data System (ADS)

    Wu, Z.

    2016-12-01

    The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30% of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land-atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades.

  2. Studies on gravity waves momentum flux variations in different seasons using MST radar

    NASA Astrophysics Data System (ADS)

    I, V.; Y-H, C.; v, S.; D, N.; S, V.

    2006-12-01

    MST radars are the best tools to study the high frequency gravity waves and its associated momentum fluxes because of excellent temporal and spatial resolutions. The upward propagating gravity waves transport energy and momentum in different regions of the atmosphere along with their propagation to produce effects at upper heights. The estimation of the vertical flux of horizontal momentum in the troposphere and lower stratosphere involves two methods, using three beams V one vertical and two oblique, and using four beams V two pairs of oblique beams systematically offset from the vertical. The rapid steerability of the Indian MST radar allows to make three and four beam measurements simultaneously. The objective of this study is to examine the variations of zonal and meridional momentum fluxes with height, variation of momentum fluxes with wave periods and body forces. We choose frequency bands corresponding to periods of 30 min-2h, 2-8 h, and 2-16h. Vertical profiles of the zonal and meridional flux in each frequency band were found to be consistent, in general, with the total flux. The study also compares momentum fluxes computed with three and four beam methods. Zonal fluxes were small at lower levels and increasingly negative (westward) at higher heights. The dominant contributions to the meridional flux occur in the lower-frequency band. The large vertical momentum flux values observed around the 16 km altitude on most of the observations are due to the presence of large zonal wind shears at that altitude. Due to their persistent southward direction of propagation the meridional momentum flux during winter and summer shows southward direction of propagation and long period waves make contributions to the momentum flux in the lower stratosphere which is comparable to that of short period waves. The detailed discussion will be presented in the meeting.

  3. Finger blood content, light transmission, and pulse oximetry errors.

    PubMed

    Craft, T M; Lawson, R A; Young, J D

    1992-01-01

    The changes in light emitting diode current necessary to maintain a constant level of light incident upon a photodetector were measured in 20 volunteers at the two wavelengths employed by pulse oximeters. Three states of finger blood content were assessed; exsanguinated, hyperaemic, and normal. The changes in light emitting diode current with changes in finger blood content were small and are not thought to represent a significant source of error in saturation as measured by pulse oximetry.

  4. Optoelectronic blood oximetry as a tool of health safety monitoring

    NASA Astrophysics Data System (ADS)

    Cysewska-Sobusiak, Anna

    2001-08-01

    A metrological approach of some selected problems connected with the significant field of biomedical optics i.e., monitoring of arterial blood oxygenation by use of the tissues as optical media exposed to the controlled light action, has been presented. The subject of the measurements based on utilization of the selection absorption properties of blood is the hemoglobin oxygen saturation. Using optoelectronic sensing allows to convert sophisticated effects of noninvasive light-living tissue interaction to electrical signals which may be convenient to measure. Pulse oximetry which is based upon such a way of sensing and processing, is the recent advance in noninvasive oximetry. The unique advantages of that marvelous diagnostic technique have caused to recommend pulse oximeters as standard equipment in intensive care and other critical situations impending hypoxemia appearance. However, end-users of the pulse oximeters not always are aware of that these devices fall under specific limitations, of both physiological and technical nature. The author of this paper is a metrologist and deals mainly with various interdisciplinary problems of a measurement reliability including the aspects such as uncertainty of an outcome accessible to the user, causes affecting sensitivity, resolution and repeatability of processing function, and response time and stability of results. Referring to the subject discussed herein, and taking into account some open questions, the author's contribution is her own experience in modeling as well as in in vivo measuring of transilluminated living objects. A proposed novel use of the known pulse oximetry concept may be considered as complementary results against a general review background of the achievements obtained in oximetry as the state-of-the-art, and furthermore, the developing studies which are still in progress.

  5. Retinal oximeter for the blue-green oximetry technique

    NASA Astrophysics Data System (ADS)

    Denninghoff, Kurt R.; Sieluzycka, Katarzyna B.; Hendryx, Jennifer K.; Ririe, Tyson J.; Deluca, Lawrence; Chipman, Russell A.

    2011-10-01

    Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO2) via the retinal vessels but requires a calibrated accuracy of +/-3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the blue-green oximetry (BGO) technique can provide accuracy within +/-3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO2 measurements of ~1 and ~65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of +/-2% SO2. The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry.

  6. A hand-held EPR scanner for transcutaneous oximetry

    NASA Astrophysics Data System (ADS)

    Wolfson, Helen; Ahmad, Rizwan; Twig, Ygal; Blank, Aharon; Kuppusamy, Periannan

    2015-03-01

    Cutaneous (skin) oxygenation is an important prognostic factor for the treatment of chronic wounds, skin cancer, diabetes side effects, and limb amputation. Currently, there are no reliable methods for measuring this parameter. Oximetry, using electron paramagnetic resonance (EPR) spectroscopy, is emerging as a potential tool for clinical oximetry, including cutaneous applications. The problem with EPR oximetry, however, is that the conventional EPR design requires the use of a large magnet that can generate homogeneous field across the sample, making it unattractive for clinical practice. We present a novel approach that makes use of a miniature permanent magnet, combined with a small microwave resonator, to enable the acquisition of EPR signals from paramagnetic species placed on the skin. The instrumentation consists of a hand-held, modular, cylindrical probehead with overall dimensions of 36-mm diameter and 24-mm height, with 150-g weight. The probehead includes a Halbach array of 16 pieces (4×4×8 mm3) of Sm-Co permanent magnet and a loop-gap resonator (2.24 GHz). Preliminary measurements using a Hahn-echo pulse sequence (800 echos in 20 ms) showed a signalto- noise ratio of ~70 compared to ~435 in a homogenous magnet under identical settings. Further work is in progress to improve the performance of the probehead and to optimize the hand-held system for clinical use

  7. Retinal oximeter for the blue-green oximetry technique.

    PubMed

    Denninghoff, Kurt R; Sieluzycka, Katarzyna B; Hendryx, Jennifer K; Ririe, Tyson J; Deluca, Lawrence; Chipman, Russell A

    2011-10-01

    Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO(2)) via the retinal vessels but requires a calibrated accuracy of ±3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the blue-green oximetry (BGO) technique can provide accuracy within ±3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO(2) measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ±2% SO(2). The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry.

  8. Accuracy of retinal oximetry: a Monte Carlo investigation

    NASA Astrophysics Data System (ADS)

    Liu, Wenzhong; Jiao, Shuliang; Zhang, Hao F.

    2013-06-01

    Retinal hemoglobin oxygen saturation (sO2) level is believed to be associated with the pathophysiology of several leading blinding diseases. Methods to properly measure retinal sO have been investigated for decades; however, the accuracy of retinal oximetry is still considered to be limited. The Monte Carlo simulation of photon transport in retina to examine how the accuracy of retinal oximetry is affected by local parameters is discussed. Fundus photography was simulated in a multilayer retinal model, in which a single vessel segment with 0.7 sO2 was embedded, at six optical wavelengths. Then, 200 million photons were traced in each simulation to ensure statistically stable results. The optical reflectance and energy deposit were recorded to measure sO using both the reflection method (existing retinal oximetry) and a new absorption method, photoacoustic ophthalmoscopy (PAOM). By varying the vessel diameter and melanin concentration in the retinal pigment epithelium, the relative error of sO measurement in the reflection method increased with increasing vessel diameter and melanin concentration; in comparison, the sO measurement was insensitive to these two parameters in PAOM. The results suggest that PAOM potentially can be a more accurate tool in quantifying retinal sO.

  9. Accuracy of retinal oximetry: a Monte Carlo investigation.

    PubMed

    Liu, Wenzhong; Jiao, Shuliang; Zhang, Hao F

    2013-06-01

    Retinal hemoglobin oxygen saturation (sO2) level is believed to be associated with the pathophysiology of several leading blinding diseases. Methods to properly measure retinal sO2 have been investigated for decades; however, the accuracy of retinal oximetry is still considered to be limited. The Monte Carlo simulation of photon transport in retina to examine how the accuracy of retinal oximetry is affected by local parameters is discussed. Fundus photography was simulated in a multilayer retinal model, in which a single vessel segment with 0.7 sO2 was embedded, at six optical wavelengths. Then, 200 million photons were traced in each simulation to ensure statistically stable results. The optical reflectance and energy deposit were recorded to measure sO2 using both the reflection method (existing retinal oximetry) and a new absorption method, photoacoustic ophthalmoscopy (PAOM). By varying the vessel diameter and melanin concentration in the retinal pigment epithelium, the relative error of sO2 measurement in the reflection method increased with increasing vessel diameter and melanin concentration; in comparison, the sO2 measurement was insensitive to these two parameters in PAOM. The results suggest that PAOM potentially can be a more accurate tool in quantifying retinal sO2.

  10. ROx3: Retinal oximetry utilizing the blue-green oximetry method

    NASA Astrophysics Data System (ADS)

    Parsons, Jennifer Kathleen Hendryx

    The ROx is a retinal oximeter under development with the purpose of non-invasively and accurately measuring oxygen saturation (SO2) in vivo. It is novel in that it utilizes the blue-green oximetry technique with on-axis illumination. ROx calibration tests were performed by inducing hypoxia in live anesthetized swine and comparing ROx measurements to SO 2 values measured by a CO-Oximeter. Calibration was not achieved to the precision required for clinical use, but limiting factors were identified and improved. The ROx was used in a set of sepsis experiments on live pigs with the intention of tracking retinal SO2 during the development of sepsis. Though conclusions are qualitative due to insufficient calibration of the device, retinal venous SO2 is shown to trend generally with central venous SO2 as sepsis develops. The novel sepsis model developed in these experiments is also described. The method of cecal ligation and perforation with additional soiling of the abdomen consistently produced controllable severe sepsis/septic shock in a matter of hours. In addition, the ROx was used to collect retinal images from a healthy human volunteer. These experiments served as a bench test for several of the additions/modifications made to the ROx. This set of experiments specifically served to illuminate problems with various light paths and image acquisition. The analysis procedure for the ROx is under development, particularly automating the process for consistency, accuracy, and time efficiency. The current stage of automation is explained, including data acquisition processes and the automated vessel fit routine. Suggestions for the next generation of device minimization are also described.

  11. A Different Time-Dependent Variational Principle Approach: Going Beyond Wave Packet Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Grabowski, Paul; Markmann, Andreas; Surh, Mike; Murillo, Michael; Graziani, Frank

    2012-02-01

    During inertial confinement fusion, matter evolves from a solid condensed matter phase through the warm dense matter (WDM) regime to a hot dense matter. In WDM, quantum mechanical effects are important because of both Fermi-Dirac statistics and the rate of electrons transitioning in and out of bound states is large. The time-dependent temperature and quickly changing local environment require a time-dependent quantum method. A converged dynamical quantum simulation is intractable for more than a few particles. Instead, we take as a feasible goal to match the statistical properties of a warm dense plasma. The time-dependent variational principle gives a framework for producing equations of motion. A commonly used variational form is a Hartree product of isotropic Gaussian wave packets (wave packet molecular dynamics). The resulting dynamics do not produce the right statistics. We therefore introduce a plane wave basis and discuss its advantages and test its ability to reproduce radial distribution functions produced by hyper-netted chain calculations.

  12. Theory on excitations of drift Alfvén waves by energetic particles. I. Variational formulation

    SciTech Connect

    Zonca, Fulvio; Chen, Liu

    2014-07-15

    A unified theoretical framework is presented for analyzing various branches of drift Alfvén waves and describing their linear and nonlinear behaviors, covering a wide range of spatial and temporal scales. Nonlinear gyrokinetic quasineutrality condition and vorticity equation, derived for drift Alfvén waves excited by energetic particles in fusion plasmas, are cast in integral form, which is generally variational in the linear limit; and the corresponding gyrokinetic energy principle is obtained. Well known forms of the kinetic energy principle are readily recovered from this general formulation. Furthermore, it is possible to demonstrate that the general fishbone like dispersion relation, obtained within the present theoretical framework, provides a unified description of drift Alfvén waves excited by energetic particles as either Alfvén eigenmodes or energetic particle modes. The advantage of the present approach stands in its capability of extracting underlying linear and nonlinear physics as well as spatial and temporal scales of the considered fluctuation spectrum. For these reasons, this unified theoretical framework can help understanding experimental observations as well as numerical simulation and analytic results with different levels of approximation. Examples and applications are given in Paper II [F. Zonca and L. Chen, “Theory on excitations of drift Alfvén waves by energetic particles. II. The general fishbone-like dispersion relation,” Phys. Plasmas 21, 072121 (2014)].

  13. Theory on excitations of drift Alfvén waves by energetic particles. I. Variational formulation

    NASA Astrophysics Data System (ADS)

    Zonca, Fulvio; Chen, Liu

    2014-07-01

    A unified theoretical framework is presented for analyzing various branches of drift Alfvén waves and describing their linear and nonlinear behaviors, covering a wide range of spatial and temporal scales. Nonlinear gyrokinetic quasineutrality condition and vorticity equation, derived for drift Alfvén waves excited by energetic particles in fusion plasmas, are cast in integral form, which is generally variational in the linear limit; and the corresponding gyrokinetic energy principle is obtained. Well known forms of the kinetic energy principle are readily recovered from this general formulation. Furthermore, it is possible to demonstrate that the general fishbone like dispersion relation, obtained within the present theoretical framework, provides a unified description of drift Alfvén waves excited by energetic particles as either Alfvén eigenmodes or energetic particle modes. The advantage of the present approach stands in its capability of extracting underlying linear and nonlinear physics as well as spatial and temporal scales of the considered fluctuation spectrum. For these reasons, this unified theoretical framework can help understanding experimental observations as well as numerical simulation and analytic results with different levels of approximation. Examples and applications are given in Paper II [F. Zonca and L. Chen, "Theory on excitations of drift Alfvén waves by energetic particles. II. The general fishbone-like dispersion relation," Phys. Plasmas 21, 072121 (2014)].

  14. Effects of temperature variations on guided waves propagating in composite structures

    NASA Astrophysics Data System (ADS)

    Shoja, Siavash; Berbyuk, Viktor; Boström, Anders

    2016-04-01

    Effects of temperature on guided waves propagating in composite materials is a well-known problem which has been investigated in many studies. The majority of the studies is focused on effects of high temperature. Understanding the effects of low temperature has major importance in composite structures and components which are operating in cold climate conditions such as e.g. wind turbines operating in cold climate regions. In this study first the effects of temperature variations on guided waves propagating in a composite plate is investigated experimentally in a cold climate chamber. The material is a common material used to manufacture rotor blades of wind turbines. The temperature range is 25°C to -25°C and effects of temperature variations on amplitude and phase shift of the received signal are investigated. In order to apply the effects of lowering the temperature on the received signal, the Baseline Signal Stretch (BSS) method is modified and used. The modification is based on decomposing the signal into symmetric and asymmetric modes and applying two different stretch factors on each of them. Finally the results obtained based on the new method is compared with the results of application of BSS with one stretch factor and experimental measurements. Comparisons show that an improvement is obtained using the BSS with the mode decomposition method at temperature variations of more than 25°C.

  15. Differential shear wave attenuation and its lateral variation in the North Atlantic region

    NASA Technical Reports Server (NTRS)

    Sheehan, Anne F.; Solomon, Sean C.

    1992-01-01

    A digital data base of over 150 seismograms and a spectral radio technique are used to measure SS-S differential attenuation in the North Atlantic region. Differential attenuation is positively correlated with SS-S travel time residual, and both differential attentuation and travel time residual decrease with increasing seafloor age. Models are developed for seismic Q in which lateral variations include contributions from the asthenospheric low-Q zone as well as from lithospheric cooling. The Q models obtained under this assumption are in good agreement with those obtained from surface wave studies and are therefore preferred over those models with lateral variations confined to the upper 125 km. Systematic long-wavelength (1000-7000 km) variations in differential attenuation, corrected for seafloor age, are evident along the axis of the Mid-Atlantic Ridge. These variations can be qualitatively correlated with long-wavelength variations in SS-S differential travel time residuals and are attributed to along-axis differences in upper mantle temperature.

  16. Retinal Oximetry with Scanning Laser Ophthalmoscope in Infants

    PubMed Central

    Vehmeijer, Wouter B.; Magnusdottir, Vigdis; Eliasdottir, Thorunn S.; Hardarson, Sveinn Hakon; Schalij-Delfos, Nicoline E.; Stefánsson, Einar

    2016-01-01

    Purpose Dual wavelength retinal oximetry has been developed for adults, but is not available for infants. Retinal oximetry may provide insight into the pathophysiology of oxygen-mediated diseases like retinopathy of prematurity. More insight in the oxygen metabolism of the retina in infants may provide valuable clues for better understanding and subsequent prevention or treatment of the disease. The measurements of oxygen saturation are obtained with two fundus images simultaneously captured in two different wavelengths of light. The comparison in light absorption of oxygenated and deoxygenated hemoglobin can be used to estimate the oxygen saturation within the retinal vessels by means of a software algorithm. This study aims to make retinal oximetry available for neonates. The first step towards estimating retinal oxygen saturation is determining the optical density ratio. Therefore, the purpose of this study is to image healthy newborn infants with a scanning laser ophthalmoscope and determine the optical density ratio for retinal oximetry analysis. Methods Images of the retina of full-term healthy infants were obtained with an SLO, Optomap 200Tx (Optos), with two laser wavelengths (532nm and 633nm). The infant lay face down on the lower arm of the parent, while the parent supported the chest and chin with one hand, and stabilized the back with the other hand. No mydriatics or eyelid specula were used during this study. The images were analyzed with modified Oxymap Analyzer software for calculation of the Optical Density Ratio (ODR) and vessel width. The ODR is inversely and approximately linearly related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis. Results Fifty-nine infants, (58% female), were included with mean gestational age of 40 ± 1.3 weeks (mean ± SD) and mean post-natal age of 16 ± 4.8 days. A total of 28 images were selected for retinal oximetry analysis

  17. Overhauser Magnetometers Development and Some Magnetic Field Variation and Long-wave Seismic Synchronous Registration Results

    NASA Astrophysics Data System (ADS)

    Kusonsky, O.; Sapunov, V.; Denisova, O.

    Creation experience and advantages of the cyclic Overhauser magnetometers with double polarization by magnetostatic and high-frequency magnetic fields (DC-HF OVH magnetometers) are discussed for some geophysical tasks. In particular, DC- HF OVH method provides: · The high sensitivity (0.01-0.05nT) is achievable even for the bottom geomagnetic field range (10000-40000nT), is due to the simple ESR-structure of the radical in bias DC field, and that is especially useful for applications in equatorial conditions an d space. · The record gradient tolerance (up to 40000 nT/m) useful for borehole applications is reached, that is caused by an opportunity of adaptive reduction of the proton precession signal time registration. · The high-sensitivity registration of magnetic field variations up to 0.001 nT at rate about 10 seconds and high stability (0.05 nT/year), and absolute (up to 0.1 nT) measurements are possible that is useful at ground seismic researches. Addressing this last advantage of DC-HF OVH magnetometer, the magnetic field variation and long-wave seismic synchronous investigations at the Ural magnetic observatory ARTY has been made. Magnetometer POS-1 and digital seismic station IRIS/IDA recording elastic fluctuation from 0,1 up to 1000 sec and more duration were used. The observable correlation of elastic waves and geomagnetic variations, and also superlong-wave emission can testify that the Earth crust has high strain -sensing characteristics where supervision was carried out. The latter is peculiar to lithospher ic areas at astable condition near to a destruction barrier.

  18. Adjustable fetal phantom for pulse oximetry

    NASA Astrophysics Data System (ADS)

    Stubán, Norbert; Niwayama, Masatsugu

    2009-05-01

    As the measuring head of a fetal pulse oximeter must be attached to the head of the fetus inside the mother's uterus during labor, testing, and developing of fetal pulse oximeters in real environment have several difficulties. A fetal phantom could enable evaluation of pulse oximeters in a simulated environment without the restrictions and difficultness of medical experiments in the labor room. Based on anatomic data we developed an adjustable fetal head phantom with three different tissue layers and artificial arteries. The phantom consisted of two arteries with an inner diameter of 0.2 and 0.4 mm. An electronically controlled pump produced pulse waves in the arteries. With the phantom we investigated the sensitivity of a custom-designed wireless pulse oximeter at different pulsation intensity and artery diameters. The results showed that the oximeter was capable of identifying 4% and 2% changes in diameter between the diastolic and systolic point in arteries of over 0.2 and 0.4 mm inner diameter, respectively. As the structure of the phantom is based on reported anatomic values, the results predict that the investigated custom-designed wireless pulse oximeter has sufficient sensitivity to detect the pulse waves and to calculate the R rate on the fetal head.

  19. A Variational Formulation for the Finite Element Analysis of Sound Wave Propagation in a Spherical Shell

    NASA Technical Reports Server (NTRS)

    Lebiedzik, Catherine

    1995-01-01

    Development of design tools to furnish optimal acoustic environments for lightweight aircraft demands the ability to simulate the acoustic system on a workstation. In order to form an effective mathematical model of the phenomena at hand, we have begun by studying the propagation of acoustic waves inside closed spherical shells. Using a fully-coupled fluid-structure interaction model based upon variational principles, we have written a finite element analysis program and are in the process of examining several test cases. Future investigations are planned to increase model accuracy by incorporating non-linear and viscous effects.

  20. Inter-Annual Variation of Gravity Waves in the Arctic and Antarctic Winter Middle Atmosphere

    DTIC Science & Technology

    2006-01-01

    mls.jpl.nasa.gov (J.H. Jiang). www.elsevier.com/locate/asr Advances in Space Research 38 (2006) 2418–2423 Report Documentation Page Form ApprovedOMB...inter-annual variations, Fig. 4 plots hemispheric maps of stratospheric gravity wave J.H. Jiang et al. / Advances in Space Research 38 (2006) 2418–2423...MLS measurement days that went into this variance map. No UKMO wind data available at 80 km. 2420 J.H. Jiang et al. / Advances in Space Research 38

  1. Pulse Oximetry Overestimates Oxyhemoglobin in Neonates with Critical Congenital Heart Disease.

    PubMed

    Murphy, Daniel; Pak, Youngju; Cleary, John Patrick

    2016-01-01

    Pulse oximetry is a key part of the clinical evaluation and management of neonates with congenital heart defects. In 2011, the US Department of Health and Human Services recommended use of routine pulse oximetry to screen for critical congenital heart disease (CCHD). Current studies suggest pulse oximetry overestimates arterial oxygen saturation in moderately hypoxemic pediatric patients. Based on variable hypoxemia in neonates with CCHD, concern exists that present pulse oximeter technology may overestimate measured oxyhemoglobin. To compare pulse oximetry and oxyhemoglobin values in NICU patients with known CCHD to evaluate the ability of pulse oximetry to reliably predict oxyhemoglobin accounting for potential confounding variables such as heart lesion, saturation range, total hemoglobin concentration, peripheral perfusion, and timing of measurements. This is a single-center retrospective study. Inclusion criteria were AHA-defined CCHD and umbilical artery blood gas-derived oxyhemoglobin with concurrent pulse oximetry recording during hours of life 0-72. Bland-Altman analysis and the concordance correlation coefficient were used to measure the internal consistency (agreement) between the two measurements. 89 patients were evaluated with 599 paired arterial oxyhemoglobin and pulse oximetry recordings. 47% of all pulse oximetry values were ≥95% - the cutoff for CCHD screening. Pulse oximetry overestimated arterial oxyhemoglobin by a mean of 5.4% over all levels of oxygen saturation. Pulse oximetry overestimation was >3 in 65.4% of measurements, >6 in 41.2% of measurements, and >10 in 15.3% of measurements. Hour of life, total hemoglobin, and peripheral perfusion did not significantly affect the degree of overestimation. Our results reinforce the concern that present pulse oximeters overestimate oxyhemoglobin values, contributing to some false-negative CCHD screens and potentially leading to unnecessary escalations in care of those patients with diagnosed CCHD

  2. Projection of heat waves variation over a warming climate in China

    NASA Astrophysics Data System (ADS)

    Yue, X.; Wu, S.; Pan, T.

    2016-12-01

    Heat waves (HW) have adverse impacts on economies, human health, societies and environment, which have been observed around the world and are expected to increase in a warming climate. However, the variations of HW under climate change over China are not clear yet. Using the HadGEM2-ES RCP4.5 and RCP8.5 daily maximum temperature and humidity dataset, variation of heat waves in China for 2021-2050 comparing to 1991-2000 as baseline were analyzed. The CMA-HI (Heat Index standardized by China Meteorological Administration) index was used to calculate the frequency and intensity of head waves. This paper classified the HW into three intensity levels including mild HW, moderate HW and severe HW , and defined a heat wave event (HWE) as that CMA-HI are all above or equal to 2.8 and keep at a intensity level more than five consecutive days. Results show that during 2021to 2050, the distribution area, frequency and duration of each intensity level have an increasing trend over China, and those of severe HW will increase mostly. The distribution area of mild, moderate and severe HW will increase 18%, 22%, 35% respectively. Average HWE frequency of each level will concentrate on 0.5-1instead of 0-0.3 in baseline period. Maximum frequency of each intensity can reach to almost 3 times a year. During 1991-2000, the average frequency of mild HW, moderate HW and severe HW kept a downward sequence. But it will change to increase in the future, and the shift occurs during 2031-2040. In addition, only severe HW duration will increase in the future. Its average value will increase from 9days to 13days, and keep a maximum duration of 42days.While the average duration of mild HW and moderate HW just keep almost 6 days and 8 days as usual. Regionally, both the frequency and duration will keep high value in the region of eastern China, central China, southern China and central Xinjiang autonomous region in the future. And only severe HW has a great change in distribution. Under RCP 8

  3. A theoretical model for optical oximetry at the capillary-level by optical coherence tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

    2017-02-01

    Oxygen saturation (sO2) of RBCs in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e. measuring hemoglobin sO2) is feasible from dispersed red blood cells (RBCs) at the single-capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. Here we provide a theoretical model to calculate the backscattering spectra of single RBCs based on the first-order Born approximation, considering the orientation, size variation, and deformation of RBCs. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different deformations of RBCs, allowing the sO2 of individual RBCs in capillaries to be characterized. The theoretical model is verified by Mie theory and experiments using visible light optical coherence tomography (vis-OCT). Thus, this study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single-capillary level by backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single-capillary level. This is promising for in vivo backscattering-based optical oximetry at the single-capillary level, to measure local capillary sO2 for early diagnosis, progression monitoring, and treatment evaluation of diabetic retinopathy and cancer.

  4. Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

    NASA Technical Reports Server (NTRS)

    Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

    2013-01-01

    We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

  5. Relativistic blast-wave model for the rapid flux variations of AO 0235+164 and other compact radio sources

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.

    1978-01-01

    A relativistic blast-wave version of a signal-screen model is developed which can adequately explain the details of the flux-density and structural variations of compact extragalactic radio sources. The relativistic motion implied by flux variations is analyzed with respect to the synchrotron spectrum of the BL Lac object AO 0235+164 observed during outbursts, and a signal-screen model for rapidly expanding shells produced by ultrarelativistic blast waves is examined. The approximate observed structure of the blast wave at three stages in its evolution is illustrated, each stage is described, and the model is applied to the flux density outburst in AO 0235+164 observed in late 1975. The results show that a relativistic blast-wave model can in general reproduce the main features of the observed flux variations in compact sources. Some problems with the proposed model are briefly discussed.

  6. Measurement of velocity variations along a wave path in the through-thickness direction in a plate.

    PubMed

    Kawashima, Katsuhiro

    2005-01-01

    In this paper there is given a method to predict ultrasonic wave velocity variations along a wave path in the through-thickness direction in a plate from thickness resonance spectra. Thickness resonance spectra are numerically calculated and two simple rules used to predict the entire ultrasonic wave velocity variation are derived. In the calculation, the wave path is assumed to be straight along the thickness direction and the velocity variation is assumed to be either as a parabolic curve dependence or a linear dependence with respect to the distance from the surface and to be symmetric with respect to the plate center. To see if the numerical calculation method is reliable, thickness resonance frequencies of a sample with three-layers were measured by EMAT (electromagnetic acoustic transducer) with a good agreement between the measured and the calculated frequencies. This method can be applied to the ultrasonic measurement of material characteristics, internal stress or various other properties of plate materials.

  7. A physical model study of converted wave amplitude variation in a reservoir of systematically aligned vertical fractures

    NASA Astrophysics Data System (ADS)

    Chang, C.; Sun, L.; Lin, C.; Chang, Y.; Tseng, P.

    2013-12-01

    The existence of fractures not only provides spaces for the residence of oils and gases reside, but it also creates pathways for migration. Characterizing a fractured reservoir thus becomes an important subject and has been widely studied by exploration geophysicists and drilling engineers. In seismic anisotropy, a reservoir of systematically aligned vertical fractures (SAVF) is often treated as a transversely isotropic medium (TIM) with a horizontal axis of symmetry (HTI). Subjecting to HTI, physical properties vary in azimuth. P-wave reflection amplitude, which is susceptible to vary in azimuth, is one of the most popular seismic attributes which is widely used to delineate the fracture strike of an SAVF reservoir. Instead of going further on analyzing P-wave signatures, in this study, we focused on evaluating the feasibility of orienting the fracture strike of an SAVF reservoir using converted (C-) wave amplitude. For a C-wave is initiated by a downward traveling P-wave that is converted on reflection to an upcoming S-wave; the behaviors of both P- and S-waves should be theoretically woven in a C-wave. In our laboratory work, finite offset reflection experiments were carried out on the azimuthal plane of a HTI model at two different offset intervals. To demonstrate the azimuthal variation of C-wave amplitude in a HTI model, reflections were acquired along the principal symmetry directions and the diagonal direction of the HTI model. Inheriting from phenomenon of S-wave splitting in a transversely isotropic medium (TIM), P-waves get converted into both the fast (S1) and slow (S2) shear modes at all azimuths outside the vertical symmetry planes, thus producing split PS-waves (PS1 and PS2). In our laboratory data, the converted PS1- (C1-) wave were observed and identified. As the azimuth varies from the strike direction to the strike normal, C1-wave amplitude exhibits itself in a way of weakening and can be view from the common-reflection-point (CRP) gathers

  8. Global and seasonal variations in three-dimensional gravity wave momentum flux from satellite limb-sounding temperatures

    NASA Astrophysics Data System (ADS)

    Alexander, M. Joan

    2015-08-01

    Satellite limb-sounding methods provide the best global temperature data available for simultaneous measurement of gravity wave horizontal and vertical structures needed to estimate momentum flux and constrain wave effects on general circulation. Gravity waves vary in the three spatial dimensions and time, so the ideal measurement observes all three dimensions at high resolution nearly simultaneously. High Resolution Dynamics Limb Sounder (HIRDLS) measurements give near-simultaneous profiles in close proximity and at high vertical resolution, but these coincident profiles lie only along the plane of the measurement track. Here we combine HIRDLS and radio occultation data sets to obtain three-dimensional properties of gravity waves on a global scale as well as seasonal variations. The results show dramatic changes from previous estimates using either data set alone. Changes include much larger momentum fluxes and latitudinal variations in propagation direction that support an enhanced role for gravity wave forcing of middle atmosphere circulation.

  9. Test of a processing algorithm for NIR-laser-diode-based pulse oximetry

    NASA Astrophysics Data System (ADS)

    Lopez Silva, Sonnia M.; Silveira, Juan Pedro; Dotor, Maria Luisa

    2003-04-01

    Pulse oximeters are used for the non-invasive monitoring of arterial blood hemoglobin oxygen saturation. This technique is based on the time variable optical attenuation by a vascular bed due to the cardiac pumping action (photoplethysmography) and the differential optical absorption of the oxy- and deoxy-hemoglobin. The photoplethysmographic (PPG) signals measured at two specific wavelengths are decomposed into its variable or pulsating component (EAC) and the constant or non-pulsating component (EDC) for deriving a parameter related to the arterial blood oxygen saturation (So2). Previously it has been reported a signal processing algorithm for a near infrared (NIR) laser diodes based transmittance pulse oximetry system. The main difficulties in the extraction of the information from the PPG signals are the small value of the signals variation related to their constant values, and the presence of artefacts caused by macro- and micro- movements of the part under analysis. The proposed algorithm permits the numeric separation of the variable and constant parts of the signals for both wavelengths. The EDC is obtained by a low pass filtering, and EAC by a pass-band one, followed by a non-linear filtering based on histogram reduction. In the present work is exposed the analysis of the influence of processing parameters like filters cut-off frequencies and histogram reduction percentage, on the derived So2 values. The test has been conducted both on real and simulated PPG signals. The real PPG has been recorded through experimental studies with human subjects using the NIR laser diodes based transmittance pulse oximetry system. The sources of artefacts and noise in the laser diodes PPG signals are discussed.

  10. A Different Time-Dependent Variational Principle Approach: Going Beyond Wave Packet Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Grabowski, Paul; Markmann, Andreas; Murillo, Michael; Graziani, Frank; Cimarron Collaboration

    2011-10-01

    During inertial confinement fusion, matter evolves from a solid condensed matter phase through the warm dense matter (WDM) regime to a hot dense matter. In WDM, quantum mechanical effects are important because of both Fermi-Dirac statistics and the rate of electrons transitioning in and out of bound states is large. The time-dependent temperature and quickly changing local environment require a time-dependent quantum method. A converged dynamical quantum simulation is intractable for more than a few particles. Instead, we take as a feasible goal to match the statistical properties of a warm dense plasma. The time-dependent variational principle gives a framework for producing equations of motion. A commonly used ansatz is a Hartree product of isotropic Gaussian wave packets (wave packet molecular dynamics). The resulting dynamics do not produce the right statistics. We therefore introduce a plane wave basis and discuss its advantages and test its ability to reproduce radial distribution functions produced by hyper-netted chain calculations.

  11. Understanding the variation in the millimeter-wave emission of Venus

    NASA Technical Reports Server (NTRS)

    Fahd, Antoine K.; Steffes, Paul G.

    1992-01-01

    Recent observations of the millimeter-wave emission from Venus at 112 GHz (2.6 mm) have shown significant variations in the continuum flux emission that may be attributed to the variability in the abundances of absorbing constituents in the Venus atmosphere. Such constituents include gaseous H2SO4, SO2, and liquid sulfuric acid (cloud condensates). Recently, Fahd and Steffes have shown that the effects of liquid H, SO4, and gaseous SO2 cannot completely account for this measured variability in the millimeter-wave emission of Venus. Thus, it is necessary to study the effect of gaseous H2SO4 on the millimeter-wave emission of Venus. This requires knowledge of the millimeter-wavelength (MMW) opacity of gaseous H2SO4, which unfortunately has never been determined for Venus-like conditions. We have measured the opacity of gaseous H2SO4 in a CO2 atmosphere at 550, 570, and 590 K, at 1 and 2 atm total pressure, and at a frequency of 94.1 GHz. Our results, in addition to previous centimeter-wavelength results are used to verify a modeling formalism for calculating the expected opacity of this gaseous mixture at other frequencies. This formalism is incorporated into a radiative transfer model to study the effect of gaseous H2SO4 on the MMW emission of Venus.

  12. The Impact of Reduced Pulse Oximetry Use on Alarm Frequency.

    PubMed

    Schondelmeyer, Amanda C; Brady, Patrick W; Sucharew, Heidi; Huang, Guixia; Hofacer, Kelsey E; Simmons, Jeffrey M

    2016-04-01

    Concerns about alarm fatigue prompted The Joint Commission to issue a Sentinel Event Alert urging hospitals to minimize alarms. We previously conducted a quality improvement project on a single unit that reduced time on continuous pulse oximetry, a common source of physiologic monitor alarms, for patients with wheezing (ie, asthma and bronchiolitis, wheezing-associated respiratory infections). To study the impact of our improvement work on overall physiologic monitor alarm frequency for these patients. This was a retrospective cohort study at a freestanding children's hospital over an 8-week period. We compared alarm count, including respiratory, cardiac, and pulse oximetry alarms, for patients admitted to the intervention unit with the alarm count for similar patients on a control unit by using the Wilcoxon rank sum test. We used negative binomial regression to evaluate differences in alarm count between the units, adjusting for age, medical comorbidity, and length of stay. There were 101 patients on the intervention unit and 46 patients on the control unit. The percentage of patients with medical comorbidities was significantly higher on the intervention unit (P=.01). Median alarm count per day for patients on the intervention unit was lower; however, this difference was not statistically significant (71 vs 76 alarms per patient-day, P=.29). The multivariable model estimated a nonsignificant 6.4-count decrease in alarms for patients on the intervention unit. Reducing continuous pulse oximetry use alone may not make substantial reductions in overall alarm counts. Even on our intervention unit, alarm burden remained quite high. Copyright © 2016 by the American Academy of Pediatrics.

  13. Public Views on Pulse Oximetry Screening for Critical Congenital Heart Disease.

    PubMed

    Kumar, Praveen; Iyengar, Hari; Kumar, Prerna

    2017-03-01

    To understand public views on pulse oximetry screening for critical congenital heart disease. Two hundred thirteen adults read a brief vignette describing the importance of early detection of critical congenital heart disease and then answered five questions on a five-point scale of how likely or unlikely they were to support pulse oximetry screening. Responses were tabulated and analyzed using a Fisher exact test, and logistic regression was used to estimate odds ratios for adjusted associations using generalized estimating equations. Almost 90% of all participants expressed support for routine pulse oximetry screening. The possibility of false positives leading to a delay in discharge, and the potential need for transfer to another facility lowered support but did not reach a statistical significance. The overall support for pulse oximetry screening was strong and consistent between different participant demographics. A large majority of participants in this study support pulse oximetry screening for the early detection of critical congenital heart disease.

  14. Visible-light optical coherence tomography for retinal oximetry.

    PubMed

    Yi, Ji; Wei, Qing; Liu, Wenzhong; Backman, Vadim; Zhang, Hao F

    2013-06-01

    We applied a visible-light spectroscopic optical coherence tomography (vis-OCT) for in vivo retinal oximetry. To extract hemoglobin oxygen saturation (sO(2)) in individual retinal vessels, we established a comprehensive analytical model to describe optical absorption, optical scattering, and blood cell packing factor in the whole blood and fit the acquired vis-OCT signals from the bottom of each imaged vessel. We found that averaged sO(2) values in arterial and venous bloods were 95% and 72%, respectively.

  15. Seasonal and interannual variations of mesospheric gravity waves and background winds

    NASA Astrophysics Data System (ADS)

    Hoffmann, P.; Rapp, M.; Becker, E.; Placke, M.

    2011-12-01

    The seasonal variation of the activity of gravity waves (GW) in the mesosphere/lower thermosphere is investigated using wind measurements with meteor and MF radars at Juliusruh (55°N, 13°E) and Andenes (69°N, 16°E), as well as on the basis of the simulated annual cycle using a gravity-wave resolving mechanistic general circulation model. Observational and computational results show the strongest GW energy during winter and a secondary maximum during summer. Additional observational analysis of short-period GWs yields a more pronounced summer maximum. The semi-annual variation is consistent with the selective filtering of westward and eastward GWs by the mean zonal wind. The latitudinal dependence during summer is characterized by stronger GW energy between 65 and 85 km at middle latitudes than at polar latitudes, and a corresponding upward shift of the wind reversal towards the pole which is also reflected by the simulated GW drag. Based on long term measurements of mesospheric winds at mid and polar altitudes, the interannual variations of the activity of GW with different periods and their dependence from the background winds are investigated. First results indicate that the observed zonal wind trend at about 75 km during summer at mid latitudes goes along with an enhanced activity of GW with periods between 3 - 6 hours at altitudes between 80 and 88 km. We will continue our studies of GW trends for other seasons at both latitudes to illuminate the contribution of the selective GW filtering by the background winds.

  16. Variation of Fundamental Mode Surface Wave Group Velocity Dispersion in Iran and the Surrounding Region

    NASA Astrophysics Data System (ADS)

    Rham, D. J.; Preistley, K.; Tatar, M.; Paul, A.

    2006-12-01

    We present group velocity dispersion results from a study of regional fundamental mode Rayleigh and Love waves propagating across Iran and the surrounding region. Data for these measurements comes from field deployments within Iran by the University of Cambridge (GBR) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), in addition to data from IRIS and Geofone. 1D path- averaged dispersion measurements have been made for ~5500 source-receiver paths using multiple filter analysis. We combine these observations in a tomographic inversion to produce group velocity images between 10 and 60 s period. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. We observe variations in short-period wave group velocity which is consistent with the surface geology. Low group velocities (2.00-2.55 km/s) at short periods (10-20 s), for both Rayleigh and Love waves are observed beneath thick sedimentary deposits; The south Caspian Basin, Black Sea, the eastern Mediterranean, the Persian Gulf, the Makran, the southern Turan shield, and the Indus and Gangetic basins. Somewhat higher group velocity (2.80-3.15 km/s for Rayleigh, and 3.00-3.40 km/s for Love) at these periods occur in sediment poor regions, such as; the Turkish-Iranian plateau, the Arabian shield, and Kazakhstan. At intermediate periods (30-40 s) group velocities over most of the region are low (2.65-3.20 km/s for Rayleigh, and 2.80-3.45 km/s for love) compared to Arabia (3.40-3.70 km/s Rayleigh, 3.50-4.0 km/s Love). At longer periods (50-60 s) Love wave group velocities remain low (3.25-3.70 km/s) over most of Iran, but there are even lower velocities (2.80-3.00 km/s) still associated with the thick sediments of the south Caspian basin, the surrounding shield areas have much higher group velocities (3

  17. (19)F Oximetry with semifluorinated alkanes.

    PubMed

    Kegel, Stefan; Chacon-Caldera, Jorge; Tsagogiorgas, Charalambos; Theisinger, Bastian; Glatting, Gerhard; Schad, Lothar R

    2016-12-01

    This work examines the variation of longitudinal relaxation rate R1(= 1/T1) of the (19)F-CF3-resonance of semifluorinated alkanes (SFAs) with oxygen tension (pO2), temperature (T) and pH in vitro. Contrary to their related perfluorocarbons (PFCs), SFA are amphiphilic and facilitate stable emulsions, a prerequisite for clinical use. A linear relationship between R1 and pO2 was confirmed for the observed SFAs at different temperatures. Using a standard saturation recovery sequence, T1 has been successfully measured using fluorine (19)F-MRI with a self-constructed birdcage resonator at 9.4 T. A calibration curve to calculate pO2 depending on T and R1 was found for each SFA used. In contrast to the commonly used PFC, SFAs are less sensitive to changes in pO2, but more sensitive to changes in temperature. The influence of pH to R1 was found to be negligible.

  18. Theoretical model for optical oximetry at the capillary level: exploring hemoglobin oxygen saturation through backscattering of single red blood cells

    NASA Astrophysics Data System (ADS)

    Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

    2017-02-01

    Oxygen saturation (sO2) of red blood cells (RBCs) in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e., measuring hemoglobin sO2) is feasible from dispersed RBCs at the single capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. We present a numerical study of backscattering spectra from single RBCs based on the first-order Born approximation, considering practical factors: RBC orientations, size variation, and deformations. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different mean cellular hemoglobin content and different deformations of RBCs. This study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single capillary level using backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single capillary level.

  19. Sms1: Seismic Wave Velocities Variations With Tectonic Stress From Controlled Source Experiment.

    NASA Astrophysics Data System (ADS)

    Chastin, Sebastien; Crampin, Stuart; Shear-Wave Analysis Group

    We present clear observations of seismic velocity variations following comparatively distant seismic activity and a consequently change in tectonic stress. The Stress- Monitoring Site SMSITES at Húsavík in Northern Iceland, described in paper SMS2 at this meeting, was used to monitor short-term variations in absolute seismic velocity. The survey took place between the 10th and 23rd of August 2001. The signal from the controlled source, a DOV (Downhole Orbital Vibrator), was transmitted repeatedly between two boreholes at 315m-offset along a single sub- horizontal direct ray path ray path at ~500m depth. The azimuthal direction between the wells is almost parallel to the strike of the Húsavík-Flatey Transform Fault (HFF) of the Mid-Atlantic Ridge, and is about 200m from the surface break. Source and receivers are in a 200m-thick layer of sandstone sandwiched between fractured layers. The DOV source was swept every 12s and the three-component recordings summed every 100 sweeps. This routine was repeated 24hours a day for 13days. Statistical analysis of the source signal stability indicates the source is coherent at 20µs and that velocity variations can be resolved at close to 1 part in 10-5. Variations in relative velocities of 2% to 5%, are observed peak to peak for Vp, Vsh, and Vsv. The behaviour of P-wave and S-wave velocities is strikingly different and correlates with a swarm of ~110 waves velocities and a sudden 4% decrease of Vp. Following the swarm, Vp increases linearly, whereas Vs follows a typical "S"-shaped relaxation-curve increase to higher (presumably equilibrium) values. This is believed to be the first time that such well

  20. Electronic states in low-dimensional nano-structures: Comparison between the variational and plane wave basis method

    NASA Astrophysics Data System (ADS)

    Hu, Min; Wang, Hailong; Gong, Qian; Wang, Shumin

    2017-04-01

    A comparison is made between the plane wave basis and variational method. Within the framework of effective-mass approximation theory, the variational and plane wave basis method are used to calculate ground state energy and ground state binding energy in low-dimensional nano-structures under the external electric field. Comparing calculation results, the donor binding energies of ground state display the consistent trend, both of them are strongly dependent on the quantum size, impurity position and external electric field. However, the impurity ground state energy calculated using variational method may be larger than the real value and it results in the smaller binding energy for variational method. In addition, the binding energy is more sensitive to the external electric field for the variational method, which can be seen more clearly from Stark shift.

  1. Momentum flux of convective gravity waves derived from an off-line gravity wave parameterization: Spatiotemporal variations at source level

    NASA Astrophysics Data System (ADS)

    Kang, Min-Jee; Chun, Hye-Yeong; Kim, Young-Ha

    2017-04-01

    Spatiotemporal variations in momentum flux spectra of convective gravity waves (CGWs) at the source level (cloud top), including nonlinear forcing effects, are examined using an off-line version of CGW parameterization and global reanalysis data. We used 1-hourly NCEP Climate Forecast System Reanalysis (CFSR) forecast data for a period of 32 years (1979-2010), with a horizontal resolution of 1° x1°. The cloud-top momentum flux (CTMF) is not solely proportional to the convective heating rate but is affected by the wave-filtering and resonance factor (WFRF), background stability and temperature underlying the convection. Consequently, the primary peak of CTMF is in the winter hemisphere midlatitude in association with storm-track region where secondary peak of convective heating exists, whereas the secondary peak of CTMF appears in the summer hemisphere tropics and intertropical convergence zone (ITCZ), where primary peak of convective heating exists. The magnitude of CTMF fluctuates largely with 1 year and 1 day periods, commonly in major CTMF regions. At low latitudes and Pacific storm track region, a 6-month period is also significant, and the decadal cycle appears in the Asian summer monsoon region and the Andes Mountains. The equatorial eastern Pacific region exhibits substantial inter-annual to decadal scale of variability with decreasing trend that is described as statistically significant. Interestingly, the correlation between convective heating and the CTMF is relatively lower in the equatorial region than in other regions. The CTMF spectra in the large-CTMF regions reveal that the spectrum shape and width changes with season and location, along with anisotropic shape of the CTMF spectrum, caused by changes in wind speed at the cloud top and the moving speed of convection. The CTMF in the 10°N to 10°S during the period of February to May 2010, when the PreConcordiasi campaign held, approximately follows a lognormal distribution but with a slight

  2. Assessing diabetic foot ulcer development risk with hyperspectral tissue oximetry

    NASA Astrophysics Data System (ADS)

    Yudovsky, Dmitry; Nouvong, Aksone; Schomacker, Kevin; Pilon, Laurent

    2011-02-01

    Foot ulceration remains a serious health concern for diabetic patients and has a major impact on the cost of diabetes treatment. Early detection and preventive care, such as offloading or improved hygiene, can greatly reduce the risk of further complications. We aim to assess the use of hyperspectral tissue oximetry in predicting the risk of diabetic foot ulcer formation. Tissue oximetry measurements are performed during several visits with hyperspectral imaging of the feet in type 1 and 2 diabetes mellitus subjects that are at risk for foot ulceration. The data are retrospectively analyzed at 21 sites that ulcerated during the course of our study and an ulceration prediction index is developed. Then, an image processing algorithm based on this index is implemented. This algorithm is able to predict tissue at risk of ulceration with a sensitivity and specificity of 95 and 80%, respectively, for images taken, on average, 58 days before tissue damage is apparent to the naked eye. Receiver operating characteristic analysis is also performed to give a range of sensitivity/specificity values resulting in a Q-value of 89%.

  3. NIR transmittance puse oximetry system with laser diodes

    NASA Astrophysics Data System (ADS)

    Lopez Silva, Sonnia M.; Silveira, Juan P.; Sendra, Jose R.; Giannetti, Romano; Dotor, Maria L.; Golmayo, Dolores

    2001-05-01

    A transmittance pulse oximetry system based on near-infrared laser diodes (LD) for monitoring arterial blood hemoglobin oxygen saturation (So2) has been previously reported. In this work we present the results obtained after improvements in the sensor configuration, signal processing algorithm and calibration procedure. The pulse oximetry system also comprises the sensor electronics, and a data acquisition board installed on a handheld personal computer. The two LD chips are mounted on a single metal heat-sink and as photo- detectors are used silicon p-i-n photodiodes with the first amplifier stage situated in their back side. The real time calculation of the parameters related to So2 is carried out through a numeric separation of the pulsatile and non- pulsatile components of the photoplethysmographic signals for both wavelengths and a non-linear filtering. Patients with respiratory failure conditions were monitored as a part of the calibration procedure in order to cover a wide range of So2-values. A calibration curve have been derived through the determination of in vitro arterial So2 with a significant quantity of experimental points ranging from 60 to almost 100%. The obtained results demonstrate that it is possible to apply the proposed system to monitoring a wide range of oxygen saturation levels.

  4. Detection of the optimal region of interest for camera oximetry.

    PubMed

    Karlen, Walter; Ansermino, J Mark; Dumont, Guy A; Scheffer, Cornie

    2013-01-01

    The estimation of heart rate and blood oxygen saturation with an imaging array on a mobile phone (camera oximetry) has great potential for mobile health applications as no additional hardware other than a camera and LED flash enabled phone are required. However, this approach is challenging as the configuration of the camera can negatively influence the estimation quality. Further, the number of photons recorded with the photo detector is largely dependent on the optical path length, resulting in a non-homogeneous image. In this paper we describe a novel method to automatically detect the optimal region of interest (ROI) for the captured image to extract a pulse waveform. We also present a study to select the optimal camera settings, notably the white balance. The experiments show that the incandescent white balance mode is the preferable setting for camera oximetry applications on the tested mobile phone (Samsung Galaxy Ace). Also, the ROI algorithm successfully identifies the frame regions which provide waveforms with the largest amplitudes.

  5. Effect of compositional variation on the shock wave response of bulk amorphous alloys

    NASA Astrophysics Data System (ADS)

    Jaglinski, T.; Turneaure, Stefan J.; Gupta, Y. M.

    2012-09-01

    The objective of this work was to determine how variations in composition influence the shock wave response of bulk amorphous alloys (BAAs). Toward this end, (Hf,Zr)-based bulk amorphous alloy specimens (nominal composition of (Hf0.5Zr0.5)56.7Cu15.3Ni12.5Nb5.0Al10.0Y0.5) were subjected to peak stresses of 4-16 GPa in plate impact experiments and their response was compared to a previously studied Zr-based BAA (nominal composition of Zr56.7Cu15.3Ni12.5Nb5.0Al10.0Y0.5). The (Hf,Zr)-based BAA displayed a Hugoniot elastic limit (HEL) of ˜7.4 GPa corresponding to an elastic strain of 4.3%. (Hf,Zr)-based BAAs shock compressed above the HEL exhibited distinct two wave structures, small elastic precursor relaxation, non-steady plastic waves, and strength loss. All of these features are qualitatively similar to previous observations in various Zr-based BAAs. One dimensional wave propagation simulations incorporating a strain-softening strength model, developed previously for a Zr-based BAA, showed excellent agreement between measured and simulated particle velocity histories for the (Hf,Zr)-based BAA. The only significant differences in the shock wave responses of the (Hf,Zr)-based alloy and the Zr-based alloy are elastic shock velocity and plastic shock velocity differences which are due to the different ambient densities and different elastic moduli for the two alloy compositions. These findings demonstrate that, apart from differences related to ambient density and elastic stiffness, the substitution of Hf for 50% of the Zr did not significantly alter the shock compression response of the (Hf,Zr)-based BAA as compared to the previously examined Zr-based BAA. Based on the results of this study and other relevant data in the literature, it is expected that monolithic BAAs displaying brittle quasi-static compression behavior will likely display shock compression response that is comparable to Zr-based and (Hf,Zr)-based BAAs.

  6. Crustal thickness variation beneath the Romanian seismic network from Rayleigh wave dispersion and receiver function analysis

    NASA Astrophysics Data System (ADS)

    Tataru, Dragos; Grecu, Bogdan; Zaharia, Bogdan

    2014-05-01

    Variations in crustal thickness in Romania where determined by joint inversion of P wave receiver functions (RFs) and Rayleigh wave group velocity dispersion. We present new models of shear wave velocity structure of the crust beneath Romanian broad band stations. The data set consist in more than 500 teleseismic earthquake with epicentral distance between 30° and 95°, magnitude greater than 6 and a signal-to-noise ratio greater than 3 for the P-wave pulse. Most epicenters are situated along the northern Pacific Rim and arrive with backazimuths (BAZs) between 0° and 135° at the Romanian seismic network. We combine receiver functions with fundamental-mode of the Rayleigh wave group velocities to further constrain the shear-wave velocity structure.To extract the group velocities we applied the Multiple Filter Technique analysis to the vertical components of the earthquakes recordings. This technique allowed us to identify the Rayleigh wave fundamental mode and to compute the dispersion curves of the group velocities at periods between 10 and 150 s allowing us to resolve shear wave velocities to a depth of 100 km. The time-domain iterative deconvolution procedure of Ligorrıa and Ammon (1999) was employed to deconvolve the vertical component of the teleseismic P waveforms from the corresponding horizontal components and obtain radial and transverse receiver functions at each broadband station. The data are inverted using a joint, linearized inversion scheme (Hermann, 2002) which accounts for the relative influence of each set of observations, and allows a trade-off between fitting the observations, constructing a smooth model, and matching a priori constraints. The results show a thin crust for stations located inside the Pannonian basin (28-30 km) and a thicker crust for those in the East European Platform (36-40 km). The stations within the Southern and Central Carpathian Orogen are characterized by crustal depths of ~35 km. For stations located in the Northern

  7. Downward Link of Solar Activity Variations Through Wave Driven Equatorial Oscillations (QBO and SAO)

    NASA Technical Reports Server (NTRS)

    Mengel, J. G.; Mayr, H. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Signatures of the 11-year solar activity/irradiance cycle are observed in the Quasi Biennial Oscillation (QBO) of the lower stratosphere. At these altitudes, the QBO is understood to be the result of "downward control" exerted by the wave mean flow interactions that drive the phenomenon. It is reasonable then to speculate that the QBO is a natural conduit to lower altitudes of solar activity variations in radiance (SAV). To test this hypothesis, we conducted experiments with a 2D version of our Numerical Spectral Model that incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). To account for the SAV, we change the solar heating rate on a logarithmic scale from 0.1% at the surface to 1% at 50 kin to 10% at 100 km. With the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the solar activity irradiance effect (SAE) on the zonal circulation at low latitudes. The numerical results obtained show that, under certain conditions, the SAE is significant in the zonal circulation and does extend to lower altitudes where the SAV is small. The differences in the wind velocities can be as large as 5 m/s at 20 kin. We carried out two numerical experiments with integrations over more than 20 years: 1) With the QBO period "tuned" to be 30 months, of academic interest but instructive, the seasonal cycle in the solar forcing [through the Semi-annual Oscillation (SAO)] acts as a strong pacemaker to produce a firm lock on the period and phase of the QBO. The SAE then shows up primarily as a distinct but relatively weak amplitude modulation. 2) With the QBO period between 30 and 34 (or less than 30, presumably) months, the seasonal phase lock is weak compared with (1). The SAV in the seasonal cycle then causes variations in the QBO period and phase, and this amplifies the SAE to produce relatively large variations in the wind field. We conclude that, under realistic conditions as in (2), the solar seasonal forcing, with

  8. Downward Link of Solar Activity Variations Through Wave Driven Equatorial Oscillations (QBO and SAO)

    NASA Technical Reports Server (NTRS)

    Mengel, J. G.; Mayr, H. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Signatures of the 11-year solar activity/irradiance cycle are observed in the Quasi Biennial Oscillation (QBO) of the lower stratosphere. At these altitudes, the QBO is understood to be the result of "downward control" exerted by the wave mean flow interactions that drive the phenomenon. It is reasonable then to speculate that the QBO is a natural conduit to lower altitudes of solar activity variations in radiance (SAV). To test this hypothesis, we conducted experiments with a 2D version of our Numerical Spectral Model that incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GW). To account for the SAV, we change the solar heating rate on a logarithmic scale from 0.1% at the surface to 1% at 50 kin to 10% at 100 km. With the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the solar activity irradiance effect (SAE) on the zonal circulation at low latitudes. The numerical results obtained show that, under certain conditions, the SAE is significant in the zonal circulation and does extend to lower altitudes where the SAV is small. The differences in the wind velocities can be as large as 5 m/s at 20 kin. We carried out two numerical experiments with integrations over more than 20 years: 1) With the QBO period "tuned" to be 30 months, of academic interest but instructive, the seasonal cycle in the solar forcing [through the Semi-annual Oscillation (SAO)] acts as a strong pacemaker to produce a firm lock on the period and phase of the QBO. The SAE then shows up primarily as a distinct but relatively weak amplitude modulation. 2) With the QBO period between 30 and 34 (or less than 30, presumably) months, the seasonal phase lock is weak compared with (1). The SAV in the seasonal cycle then causes variations in the QBO period and phase, and this amplifies the SAE to produce relatively large variations in the wind field. We conclude that, under realistic conditions as in (2), the solar seasonal forcing, with

  9. Variations in Shear Wave Splitting Beneath Southern Arabia and the Gulf of Aden

    NASA Astrophysics Data System (ADS)

    Gallacher, R. J.; Eakin, C. M.; Keir, D.; Leroy, S. D.; Stuart, G. W.; Harmon, N.; Ahmed, A.

    2015-12-01

    Mantle flow beneath Southern Arabia and the Gulf of Aden remains enigmatic due to a paucity of seismic measurements in the region. Potential processes contributing to mantle flow include northward progression of the African Superplume, radial flow from the Afar plume and vertical flow from small-scale convection along the margins of the Gulf of Aden. These would result in characteristic mantle flow directions, creating mantle anisotropy that can be detected by shear wave splitting. We analyse SKS, SKKS & PKS phases for shear wave splitting at 141 stations deployed throughout Yemen, Oman and Socotra along the margins of the Gulf of Aden. Large numbers of null measurements from a range of back azimuths are found beneath the entire region. These may indicate that vertical anisotropy is present in the upper mantle beneath the region, consistent with models of small-scale convection. The null measurements may also be due to complicated layering of crustal anisotropy interfering destructively and precluding measurement of shear wave splitting. Splitting measurements bordering the Red Sea show North-South orientations that may result from shallow aligned melt along the Red Sea or from variations in lower mantle flow. Fast polarization directions of splitting measurements along the Northern margin of the Gulf of Aden are rift parallel suggesting a shallow source such as rift related faulting might be responsible. These results show that anisotropy beneath the region is not controlled by the northward progression of the African Superplume or radial flow from the Afar plume. Upper mantle flow is likely vertical with splitting occurring either in the crust or the lower mantle.

  10. Quantum variational measurement and the optical lever intracavity topology of gravitational-wave detectors

    SciTech Connect

    Khalili, F. Ya.

    2007-04-15

    The intracavity topologies of laser gravitational-wave detectors proposed several years ago are the promising way to obtain sensitivity of these devices significantly better than the Standard Quantum Limit (SQL). In essence, the intracavity detector is a two-stage device where the end mirrors displacement created by the gravitational wave is transferred to the displacement of an additional local mirror by means of the optical rigidity. The local mirror positions have to be monitored by an additional local meter. It is evident that the local meter precision defines the sensitivity of the detector. To overcome the SQL, the quantum variational measurement can be used in the local meter. In this method a frequency-dependent correlation between the meter backaction noise and measurement noise is introduced, which allows us to eliminate the backaction noise component from the meter output signal. This correlation is created by means of an additional filter cavity. In this article the sensitivity limitations of this scheme imposed by the optical losses both in the local meter itself and in the filter cavity are estimated. It is shown that the main sensitivity limitation stems from the filter cavity losses. In order to overcome it, it is necessary to increase the filter cavity length. In a preliminary prototype experiment, an approximate 10 m long filter cavity can be used to obtain sensitivity approximately 2-3 times better than the SQL. For future Quantum Non-Demolition (QND) gravitational-wave detectors with sensitivity about 10 times better than the SQL, the filter cavity length should be within kilometer range.

  11. Numerical Assessment of Four-Port Through-Flow Wave Rotor Cycles with Passage Height Variation

    NASA Technical Reports Server (NTRS)

    Paxson, D. E.; Lindau, Jules W.

    1997-01-01

    The potential for improved performance of wave rotor cycles through the use of passage height variation is examined. A Quasi-one-dimensional CFD code with experimentally validated loss models is used to determine the flowfield in the wave rotor passages. Results indicate that a carefully chosen passage height profile can produce substantial performance gains. Numerical performance data are presented for a specific profile, in a four-port, through-flow cycle design which yielded a computed 4.6% increase in design point pressure ratio over a comparably sized rotor with constant passage height. In a small gas turbine topping cycle application, this increased pressure ratio would reduce specific fuel consumption to 22% below the un-topped engine; a significant improvement over the already impressive 18% reductions predicted for the constant passage height rotor. The simulation code is briefly described. The method used to obtain rotor passage height profiles with enhanced performance is presented. Design and off-design results are shown using two different computational techniques. The paper concludes with some recommendations for further work.

  12. Depth variations of P-wave azimuthal anisotropy beneath Mainland China

    PubMed Central

    Wei, Wei; Zhao, Dapeng; Xu, Jiandong; Zhou, Bengang; Shi, Yaolin

    2016-01-01

    A high-resolution model of P-wave anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab. PMID:27432744

  13. Depth variations of P-wave azimuthal anisotropy beneath Mainland China

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Zhao, Dapeng; Xu, Jiandong; Zhou, Bengang; Shi, Yaolin

    2016-07-01

    A high-resolution model of P-wave anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab.

  14. Depth variations of P-wave azimuthal anisotropy beneath Mainland China.

    PubMed

    Wei, Wei; Zhao, Dapeng; Xu, Jiandong; Zhou, Bengang; Shi, Yaolin

    2016-07-19

    A high-resolution model of P-wave anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab.

  15. Wave Effects Related to Altitude Variations in the Ion Composition of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Vavilov, D. I.; Shklyar, D. R.

    2016-12-01

    Properties of the waves, which can propagate in a magnetized plasma in the frequency range below the proton gyrofrequency, depend strongly on the ion composition of the plasma. Addition of a new sort of ions leads to the appearance of a new resonance frequency, at which the refractive index becomes infinite, and a new cutoff frequency, at which the refractive index becomes zero. In this case, the topology of frequency dependence of the squared refractive index changes. Specifically, a new oscillation branch appears, which is located above the cutoff frequency. A question arises whether these oscillations are excited if radiation with the corresponding frequency, which propagates in a different mode, is present in the plasma. A linear transformation of the waves is another important effect, which is related to variations in the ion plasma composition. These two issues, which are directly related to the theory of formation of proton whistlers in the ionosphere, where the ion composition varies with altitude, are considered in this work.

  16. Variational Symplectic Algorithm for Whistler Wave Ray Tracing in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Crabtree, Chris; Rudakov, Leonid; Ganguli, Gurudas; Mithaiwala, Manish

    2012-10-01

    Whistler wave ray tracing in the inner magnetosphere using the full cold plasma dispersion relation is prone to producing drifts in frequencies that lead to inaccurate ray dynamics especially in the presence of both field aligned density structures (such as ducts and plasmapause boundaries) and sharp radial gradients in multi-species plasmas (such as ionospheric layers). The computation of accurate and quick ray trajectories are especially important for developing solutions to the wave kinetic equation including nonlinear (NL) effects such as induced scattering [1] where a large number of rays need to be time advanced and energy redistributed among rays. To facilitate such a calculation we have transformed the usual canonical ray tracing equations to an extended phase space Lagrangian framework and extended the variational symplectic integrator (VSI) [2] used for guiding-center dynamics to the ray tracing equations. The VSI conserves exactly a discrete Lagrangian structure and most importantly leads to bounds in the frequency drift that can develop.[4pt] [1] C. Crabtree, L. Rudakov, G. Ganguli, M. Mithaiwala, V. Galinsky, V. Shevchenko, Phys. Plasmas 19, 032903, (2012).[0pt] [2] H. Qin and X. Guan, Phys. Rev. Lett. 100, 035006 (2008).

  17. Variation in the dispersion of axisymmetric waves in infinite circular rods with crystallographic wire texture

    SciTech Connect

    Mason, T.A. )

    1999-09-01

    This paper presents the solution to the frequency equation for a number of polycrystalline, textured circular rods having transverse isotropy. The effective, second-order elastic stiffness tensors were estimated using the recursive general Hill arithmetic mean (GHAM). The velocity dispersion curves for a number of combinations of materials and crystallographic fiber or wire textures were calculated and the variation due to texture displayed. At large wavelengths, the velocity dispersion of fiber textured materials exhibits a lowest-order axisymmetric mode which varies only with the directional Poisson[close quote]s ratios in a manner similar to that of isotropic aggregates. In this wavelength regime, the waves propagate nondispersively at the wave speed, C[sub 0], as dictated by the directional Young[close quote]s modulus. At wavelengths smaller than the rod radius, the dispersion curves were more influenced by the full anisotropy of the wire textures. At these wavelengths, the dispersion curves for the anisotropic materials deviated significantly from those of the isotropic materials and one another with the higher axisymmetric vibration modes exhibiting extreme differences. This deviation is a function of the single crystal anisotropy and nature of the wire textures. < --[AN] -->

  18. Diagnosis of PLMD from increased pulse rate variability on overnight oximetry.

    PubMed

    Krishnaswamy, Uma M; Higgins, Sean E; Kosky, Christopher A; Delacy, Simone; Williams, Adrian J

    2010-01-01

    This study was undertaken in a group of patients with periodic limb movement disorder (PLMD) to assess whether the presence of increased pulse rate variability (PRV) without desaturation on overnight oximetry was suggestive of the occurrence of periodic limb movements (PLMs). Seventy sleepy patients with a polysomnographic diagnosis of PLMD and 25 controls with obstructive sleep apnea were included in this retrospective study. All patients had undergone initial domiciliary oximetry and subsequent polysomnography (PSG). The oximetry tracings were independently interpreted by five sleep unit personnel for the presence of increased PRV. Further, the association between increased PRV and PLMs was evaluated in the summary graph of the PSG. Fifty seven (81.4%) patients had definite evidence of increased PRV without episodes of desaturation on initial oximetry, which was later confirmed to be due to PLMs on PSG. 13 (18.6%) patients had no PRV on oximetry and PSG but had PLMD. The inter-interpreter concurrence in suspecting a diagnosis of PLMD based on oximetry alone was more than 80% in 64 (91%) patients. The presence of isolated increased PRV on overnight oximetry is a valuable tool in suspecting nonsleep apnea disorders like PLMD.

  19. Diagnosis of PLMD from increased pulse rate variability on overnight oximetry

    PubMed Central

    Krishnaswamy, Uma M; Higgins, Sean E; Kosky, Christopher A; deLacy, Simone; Williams, Adrian J

    2010-01-01

    Study objective This study was undertaken in a group of patients with periodic limb movement disorder (PLMD) to assess whether the presence of increased pulse rate variability (PRV) without desaturation on overnight oximetry was suggestive of the occurrence of periodic limb movements (PLMs). Methods Seventy sleepy patients with a polysomnographic diagnosis of PLMD and 25 controls with obstructive sleep apnea were included in this retrospective study. All patients had undergone initial domiciliary oximetry and subsequent polysomnography (PSG). The oximetry tracings were independently interpreted by five sleep unit personnel for the presence of increased PRV. Further, the association between increased PRV and PLMs was evaluated in the summary graph of the PSG. Results Fifty seven (81.4%) patients had definite evidence of increased PRV without episodes of desaturation on initial oximetry, which was later confirmed to be due to PLMs on PSG. 13 (18.6%) patients had no PRV on oximetry and PSG but had PLMD. The inter-interpreter concurrence in suspecting a diagnosis of PLMD based on oximetry alone was more than 80% in 64 (91%) patients. Conclusion The presence of isolated increased PRV on overnight oximetry is a valuable tool in suspecting nonsleep apnea disorders like PLMD. PMID:23616703

  20. Seasonal variations in the Rayleigh-to-Love wave ratio in the secondary microseism from colocated ring laser and seismograph

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Hadziioannou, Céline; Igel, Heiner; Wassermann, Joachim; Schreiber, Ulrich; Gebauer, André; Chow, Bryant

    2016-04-01

    Monthly variations in the ratio of Rayleigh-to-Love waves in the secondary microseism are obtained from a colocated ring laser and an STS-2 seismograph at Wettzell, Germany. Two main conclusions are derived for the Rayleigh-to-Love wave kinetic energy ratios in the secondary microseism; first, the energy ratio is in the range 0.8-0.9 (<1.0) throughout a year except for June and July. It means that Love wave energy is larger than Rayleigh wave energy most of the year by about 10-20%. Second, this ratio suddenly increases to 1.0-1.2 in June and July, indicating a larger fraction of Rayleigh wave energy. This change suggests that the locations and behaviors of excitation sources are different in these months.

  1. Variations in Magnetic Fields Arising from Electric Currents Induced by Teleseismic Waves: Comparison between Theories and Observations

    NASA Astrophysics Data System (ADS)

    Yamazaki, K.

    2011-12-01

    Variations in the electromagnetic field accompanying earthquakes are generated by various mechanisms, of which the present study focuses on variations in the magnetic field arising from electric currents induced by teleseismic waves. As a simple but informative case, a situation is considered in which seismic waves are approximated by plane waves and the conductivity of the Earth's crust has a stratified structure. Solutions of Maxwell's equations corresponding to this situation have analytical expressions. Using the solutions, variations in the magnetic field due to Rayleigh waves are quantitatively discussed in terms of a crust with a simple structure. Numerical examples demonstrate that the amplitudes of the generated variations in the magnetic field show a monotonic increase with increasing conductivity, although depression of the amplitudes due to the skin effect of electromagnetic waves cannot be ignored. In addition, the amplitudes of the generated magnetic field are sometimes sensitive to the conductivity of both the shallow and deep crust. Given the difficulty of precisely determining the conductivity of the deep crust, it is generally problematic to obtain precise estimates corresponding to the actual Earth. Nevertheless, calculations assuming a simplified conductivity structure provide an upper limit to the possible amplitudes of variations in the magnetic field due to seismic waves. For example, the amplitudes of variations in the magnetic field arising from a Rayleigh wave with a displacement amplitude of 10 cm and a period of 30 seconds are as large as 0.1 nT, which is close to the limit of detection by fluxgate magnetometers under typical observation conditions. If variations in the magnetic field with notable amplitudes (>0.1 nT) are observed in association with seismic wave propagations, they likely imply existence of unknown mechanisms that converts mechanical motions to electromagnetic fields. To see whether this is the case, variations in the

  2. Beat to Beat: A Measured Look at the History of Pulse Oximetry.

    PubMed

    Van Meter, Antoinette; Williams, Uduak; Zavala, Acsa; Kee, Joshua; Rebello, Elizabeth; Tsai, January; Ifeanyi, Ifeyinwa; Ruiz, Joseph; Lim, Jeffery; Owusu-Agyemang, Pascal

    2017-01-01

    It can be argued that pulse oximetry is the most important technological advancement ever made in monitoring the well-being and safety of patients undergoing anesthesia. Before its development, the physical appearance of the patient and blood gas analysis were the only methods of assessing hypoxemia in patients. The disadvantages of blood gas analysis are that it is not without pain, complications, and most importantly does not provide continuous, real-time data. Although it has become de rigueur to use pulse oximetry for every anesthetic, the road leading to pulse oximetry began long ago.

  3. Parameters from preoperative overnight oximetry predict postoperative adverse events.

    PubMed

    Chung, F; Zhou, L; Liao, P

    2014-10-01

    Continuous home monitoring of oxygen saturation has become a reliable and feasible practice. The objective of this study was to investigate the role of preoperative overnight oximetry in predicting postoperative adverse events. Following research ethics board approval, consented patients underwent a preoperative overnight monitoring of oxygen saturation with a portable oximeter. Parameters from the oximetry data were extracted and their predictive performance for postoperative adverse events was evaluated. A total of 573 patients were studied with age: 60±12 years and 45% male. Oxygen desaturation index (ODI), cumulative time percentage with SpO2 <90% (CT90) and mean SpO2 were identified as significant predictors for postoperative adverse events. The privilege sensitivity, optimal predictive and privilege specificity cut-offs were: ODI: >3.0 events/h, >9.2 events/h and > 28.5 events/h; CT90: >0.1%, >1.1% and >7.2%; mean SpO2: <96.2%, <94.6% and <92.7%. The odds ratio for corresponding optimal cut-offs was: ODI 1.9 (95% CI: 1.4,2.7); CT90: 1.7 (95% CI: 1.2,2.4) and mean SpO2: 2.7 (95% CI: 1.9,3.8). The patients classified as high risk by ODI or CT90 or mean SpO2 had a significantly higher rate of postoperative adverse events. For ODI >28.5 vs. ODI ⋝28.5 events/h, the odds ratio adjusted with age, gender, body mass index and American Society of Anesthesiologists physical status was 2.2 (95% CI: 1.3-3.9). Patients with mean preoperative overnight SpO2 <92.7% or ODI >28.5 events/h or CT90 >7.2% are at higher risk for postoperative adverse events. Overnight oximetry could be a useful tool to stratify patients for the risk of postoperative adverse events.

  4. A model for seasonal changes in GPS positions and seismic wave speeds due to thermoelastic and hydrologic variations

    USGS Publications Warehouse

    Tsai, V.C.

    2011-01-01

    It is known that GPS time series contain a seasonal variation that is not due to tectonic motions, and it has recently been shown that crustal seismic velocities may also vary seasonally. In order to explain these changes, a number of hypotheses have been given, among which thermoelastic and hydrology-induced stresses and strains are leading candidates. Unfortunately, though, since a general framework does not exist for understanding such seasonal variations, it is currently not possible to quickly evaluate the plausibility of these hypotheses. To fill this gap in the literature, I generalize a two-dimensional thermoelastic strain model to provide an analytic solution for the displacements and wave speed changes due to either thermoelastic stresses or hydrologic loading, which consists of poroelastic stresses and purely elastic stresses. The thermoelastic model assumes a periodic surface temperature, and the hydrologic models similarly assume a periodic near-surface water load. Since all three models are two-dimensional and periodic, they are expected to only approximate any realistic scenario; but the models nonetheless provide a quantitative framework for estimating the effects of thermoelastic and hydrologic variations. Quantitative comparison between the models and observations is further complicated by the large uncertainty in some of the relevant parameters. Despite this uncertainty, though, I find that maximum realistic thermoelastic effects are unlikely to explain a large fraction of the observed annual variation in a typical GPS displacement time series or of the observed annual variations in seismic wave speeds in southern California. Hydrologic loading, on the other hand, may be able to explain a larger fraction of both the annual variations in displacements and seismic wave speeds. Neither model is likely to explain all of the seismic wave speed variations inferred from observations. However, more definitive conclusions cannot be made until the model

  5. Near-infrared spectral imaging of the female breast for quantitative oximetry in optical mammography

    SciTech Connect

    Yu Yang; Liu Ning; Sassaroli, Angelo; Fantini, Sergio

    2009-04-01

    We present a hybrid continuous-wave, frequency-domain instrument for near-infrared spectral imaging of the female breast based on a tandem, planar scanning of one illumination optical fiber and one collection optical fiber configured in a transmission geometry. The spatial sampling rate of 25 points/cm{sup 2} is increased to 400 points/cm{sup 2} by postprocessing the data with a 2D cubic spline interpolation. We then apply a previously developed spatial second-derivative algorithm to an edge-corrected intensity image (N-image) to enhance the visibility and resolution of optical inhomogeneities in breast tissue such as blood vessels and tumors. The spectral data at each image pixel consist of 515-point spectra over the 650-900 nm wavelength range, thus featuring a spectral density of two data points per nanometer. We process the measured spectra with a paired-wavelength spectral analysis method to quantify the oxygen saturation of detected optical inhomogeneities, under the assumption that they feature a locally higher hemoglobin concentration. Our initial measurements on two healthy human subjects have generated high-resolution optical mammograms displaying a network of blood vessels with values of hemoglobin saturation typically falling within the 60%-95% range, which is physiologically reasonable. This approach to spectral imaging and oximetry of the breast has the potential to efficiently exploit the high intrinsic contrast provided by hemoglobin in breast tissue and to contribute a useful tool in the detection, diagnosis, and monitoring of breast pathologies.

  6. The Effect of Skin Pigmentation on the Accuracy of Pulse Oximetry in Infants with Hypoxemia.

    PubMed

    Foglia, Elizabeth E; Whyte, Robin K; Chaudhary, Aasma; Mott, Antonio; Chen, Jodi; Propert, Kathleen J; Schmidt, Barbara

    2017-03-01

    To compare pulse oximetry measurement bias between infants with hypoxemia with either dark skin or light skin with Masimo Radical 7 and Nellcor Oximax. There was no significant difference in systematic bias based on skin pigment for either oximeter.

  7. At-home pulse oximetry in children undergoing adenotonsillectomy for obstructive sleep apnea.

    PubMed

    Pavone, Martino; Ullmann, Nicola; Verrillo, Elisabetta; De Vincentiis, Giancarlo; Sitzia, Emanuela; Cutrera, Renato

    2017-04-01

    Nocturnal pulse oximetry has a high positive predictive value for polysomnographically diagnosed obstructive sleep apnoea (OSA) in children. When significant adenotonsillar hypertrophy is diagnosed, adenotonsillectomy (T&A) represents a common treatment for OSA in children. We investigated the role of pulse oximetry in predicting those patients, referred for suspected OSA, who subsequently needed T&A. At-home nocturnal pulse oximetry was performed on 380 children (65.7% males), median age 4.1(IRQ 3.0-5.6) years, referred for suspected OSA, and data were retrospectively analysed. For each recording McGill Oximetry Score (MOS) was categorized. Mean pulse rate (PR) z-score and pulse rate variability (PRV)-corrected (PRSD/meanPR) were significantly higher in children with abnormal MOS. Both parameters were significantly higher in subjects who underwent T&A compared with those not surgically treated. Both DI4 and PRV corrected showed a negative correlation with the elapsed time between pulse oximetry recordings and T&A. The logistic regression model showed a strong effect of an abnormal MOS as a predicting factor for T&A (adjusted odds ratio 19.7). In our study, children with OSA who subsequently needed T&A showed higher PRV compared to those without surgical indication. Children with abnormal MOS were nearly 20 times more likely to undergo T&A. What is Known: • Nocturnal pulse oximetry has a high positive predictive value for polysomnographically diagnosed obstructive sleep apnoea in children. • When significant adenotonsillar hypertrophy is diagnosed, adenotonsillectomy represents a common treatment for OSA in children. What is New: • An abnormal pulse oximetry highly predict the indication for adenotonsillectomy. • We suggest the use of at-home pulse oximetry as method to predict prescription of adenotonsillectomy, and this may be useful in contexts where polysomnography is not readily available.

  8. Graduate nurses' knowledge of the functions and limitations of pulse oximetry.

    PubMed

    Seeley, Marie-Claire; McKenna, Lisa; Hood, Kerry

    2015-12-01

    To examine nursing graduates' knowledge of functions and limitations of pulse oximetry. Pulse oximetry is a technology ubiquitous in its use in modern clinical settings. Although the technology's ability to accurately reflect hypoxaemia in patients has been established, its contribution to improving patient outcomes is less certain. In addition, experienced nurses have previously demonstrated poor understanding of the limitations of the technology. Pregraduate education has been identified as a potential source of knowledge deficit and has been recommended by authors as an important target of investigation. Cross-sectional, comparative, multicentre study. A previously published and validated tool was used with the addition of eight clinical scenario questions which were validated by an expert panel. Convenience sampling was used to select participants to form one cohort of newly graduated nurses (Cohort 1: n = 210) and a second cohort of nurses completing their intensive postgraduate clinical year (Cohort 2: n = 97). Significant deficits relating to the theoretical factors that affect pulse oximetry application and interpretation were identified. Results suggest some knowledge is negatively correlated with clinical experience and that pregraduate university education appears to influence the ability to effectively apply pulse oximetry knowledge to clinical scenarios. This study provides insight into pulse oximetry knowledge acquisition and deficits of graduate nurses which may inform pre- and postgraduate nurse education. In particular, it suggests that some pulse oximetry knowledge and clinical application of knowledge is not enhanced by clinical experience but rather is currently gained through pregraduate experiences. Inappropriate utilisation and interpretation of pulse oximetry places patients at risk of mismanagement and undetected deterioration. Improvement in pregraduate education around the appropriate use of pulse oximetry may reduce clinical costs

  9. Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

    DTIC Science & Technology

    2015-10-01

    eyes and image choroidal vessels/capillaries using CARS intravital microscopy Subtask 3: Measure oxy-hemoglobin levels in PBI test and control eyes...AWARD NUMBER: W81XWH-14-1-0537 TITLE: Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia...4. TITLE AND SUBTITLE Mobile, Multimodal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia 5a. CONTRACT NUMBER W81XWH

  10. Maternal perceptions of labor with fetal monitoring by pulse oximetry in a research setting.

    PubMed

    Arikan, G M; Haeusler, M C; Deutsch, M T; Greimel, E R; Dorfer, M

    1998-09-01

    Little research has evaluated maternal experience with fetal pulse oximetry for fetal surveillance. The purpose of this study was to compare maternal perceptions of labor with intrapartal cardiotocography with or without fetal pulse oximetry in a research setting. One hundred women with vaginal, vertex deliveries and uncomplicated fetal outcomes were enrolled. The study group was a subset of 50 mothers who had participated in a pulse oximetry trial. The control group of 50 mothers was monitored by cardiotocography only. Both groups were matched for age, parity, weeks of gestation, epidural anesthesia use, and duration of labor. A global measure of maternal perception of labor was established by experience with labor, general attitude toward monitoring devices, satisfaction with monitoring, nursing and medical care, and anxiety, each of which was evaluated separately. The mothers in the study group were also interviewed about aspects related to the fetal pulse oximetry research setting, such as information, movement restriction, discomfort, care, privacy, and safety. The questionnaires were based on a standardized rating scale model, and the interviews were conducted two to four days after delivery. The results were analyzed by chi-squared, paired t test, and ANOVA. No significant differences were observed between the study and control participants in any parameter concerning the maternal perception of labor. Mothers' experiences with pulse oximetry as assessed by interview was overwhelmingly positive. Fetal monitoring by pulse oximetry in a research setting did not affect maternal perceptions of labor. Mothers' experiences with pulse oximetry were highly positive, suggesting that research in fetal pulse oximetry need not compromise maternal perceptions of labor.

  11. Guided waves for autonomous online identification of structural defects under ambient temperature variations

    NASA Astrophysics Data System (ADS)

    Moll, J.; Fritzen, C.-P.

    2012-09-01

    Ultrasonic guided waves that are excited by piezoelectric transducers can be used for the autonomous online identification of structural defects in thin structures. The proposed technique in this paper continuously analyzes a damage metric which is defined as the maximum residual amplitude of the differential signal. A special focus is on the decision making to discriminate the undamaged from the damaged state of the structure where the appropriate detection thresholds are derived statistically from the inverse cumulative distribution function of the damage metric during an initial training phase. An integrated trend analysis by means of the moving average mitigates the impact of statistical outliers and reduces the probability of erroneous identifications. Long-term measurements under ambient temperature variations have been conducted on an aluminum and a composite plate to study the properties of the proposed novelty detection framework. In this process the temperature effect was compensated by the well-known combination of optimal baseline selection (OBS) and baseline signal stretch (BSS). In case of the aluminum structure two artificial cracks with different sizes have been identified reliably. Consistent results were found on the composite specimen where an impact damage was identified for different excitation frequencies.

  12. Pulse oximetry screening: a review of diagnosing critical congenital heart disease in newborns.

    PubMed

    Engel, Melissa S; Kochilas, Lazaros K

    2016-01-01

    Congenital heart disease (CHD) is one of the most common birth defects, with an incidence of nine out of every 1,000 live births. The mortality of infants with CHD has decreased over the past 3 decades, but significant morbidity and mortality continue to occur if not diagnosed shortly after birth. Pulse oximetry was recommended as a screening tool to detect critical CHD in 2011 by the American Academy of Pediatrics and the American Heart Association. Pulse oximetry is a tool to measure oxygen saturation, and based on the presence of hypoxemia, many cardiac lesions are detected. Due to its ease of application to the patient, providing results in a timely manner and without the need for calibrating the sensor probe, pulse oximetry offers many advantages as a screening tool. However, pulse oximetry has also important limitations of which physicians should be aware to be able to assess the significance of the pulse oximetry measurement for a given patient. This review aims to highlight the benefits and shortcomings of pulse oximetry within the context of screening for critical CHD and suggests future avenues to cover existing gaps in current practices.

  13. [Digital and forehead pulse oximetry in Intensive Care Unit. A comparison].

    PubMed

    Palmese, Salvatore; Natale, Alfonso; Scarano, Daniele; Scibilia, Andrea C; Manzi, Maurizio

    2013-12-01

    Pulse oximetry is now a widely available technology that provides easy and continuous reliable measurements of oxygen saturation, the percentage of O2 bound to Hb (SpO2). Pulse oximetry has become a standard monitoring not only in intensive care, but also in other clinical settings, although several factors can interfere with a correct reading, as low perfusion conditions, such as low cardiac output, vasoconstriction, hypothermia. We performed a prospective observational study in two groups of twenty-eight patients admitted to the ICU, in which we compared the values ​​obtained (SpO2) with digital and forehead pulse oximetry, with arterial oxygen saturation (SaO2) obtained from blood gas analysis (EGA). Comparison measurements into two distinct groups, though homogeneous might be a limitation of the study, but at the same time provide a representative picture of a polyvalent intensive care unit. The result was that both the values ​​obtained with digital and frontal pulse oximetry are accurate and reliable in comparison to EGA. In situations of hypoxia, the reliability of frontal pulse oximetry appears superior compared to digital oximetry.

  14. Within-site variation of growth rates and terminal sizes in Mytilus californianus along wave exposure and tidal gradients.

    PubMed

    Connor, Kwasi M; Robles, Carlos D

    2015-02-01

    Mytilus californianus is a foundation species of rocky shores of western North America. Its dominance depends on rapid growth to large sizes, which confers an advantage in size-dependent species interactions. Initial rates of growth and final (terminal) sizes of the mussels depend on environmental factors. Prior comparisons of growth made over large spatial scales (tens of meters to hundreds of kilometers) indicate that temperature, submergence time, and wave exposure affect growth. However, there are few studies quantifying variation in temperature, wave force, and mussel growth parameters at small scales within local populations-that is, meter-level increments. Such measures are necessary to better understand the consequences of the complex spatial mosaic of physical factors in the intertidal zone. We measured variation in temperature, wave force, size-specific shell growth, and terminal size at 3-4-m intervals along horizontal contours within two mussel beds separated by 15 ds of latitude. Both mussel beds showed the same general trends: growth rates attenuated along gradual clines from low and wave-exposed to high shore and sheltered. For example, young adults from low and wave-exposed microhabitats grew 9- and 6-fold higher than those from high-shore-wave-sheltered points. While higher flow may promote growth by enhancing feeding, it also appears to exert a positive effect by moderating energetically costly temperature stress. Consistent with the growth rate findings, cumulative degree-hours explained 83% and 69% of the variation of terminal sizes in regressions for the two locations. © 2015 Marine Biological Laboratory.

  15. Reproducibility of transcutaneous oximetry and laser Doppler flowmetry in facial skin and gingival tissue.

    PubMed

    Svalestad, J; Hellem, S; Vaagbø, G; Irgens, A; Thorsen, E

    2010-01-01

    Laser Doppler flowmetry (LDF) and transcutaneous oximetry (TcPO(2)) are non-invasive techniques, widely used in the clinical setting, for assessing microvascular blood flow and tissue oxygen tension, e.g. recording vascular changes after radiotherapy and hyperbaric oxygen therapy. With standardized procedures and improved reproducibility, these methods might also be applicable in longitudinal studies. The aim of this study was to evaluate the reproducibility of facial skin and gingival LDF and facial skin TcPO(2). The subjects comprised ten healthy volunteers, 5 men, aged 31-68 years. Gingival perfusion was recorded with the LDF probe fixed to a custom made, tooth-supported acrylic splint. Skin perfusion was recorded on the cheek. TcPO(2) was recorded on the forehead and cheek and in the second intercostal space. The reproducibility of LDF measurements taken after vasodilation by heat provocation was greater than for basal flow in both facial skin and mandibular gingiva. Pronounced intraday variations were observed. Interweek reproducibility assessed by intraclass correlation coefficient ranged from 0.74 to 0.96 for LDF and from 0.44 to 0.75 for TcPO(2). The results confirm acceptable reproducibility of LDF and TcPO(2) in longitudinal studies in a vascular laboratory where subjects serve as their own controls. The use of thermoprobes is recommended. Repeat measurements should be taken at the same time of day.

  16. Variational full wave calculation of fast wave current drive in DIII-D using the ALCYON code

    SciTech Connect

    Becoulet, A.; Moreau, D.

    1992-04-01

    Initial fast wave current drive simulations performed with the ALCYON code for the 60 MHz DIII-D experiment are presented. Two typical shots of the 1991 summer campaign were selected with magnetic field intensities of 1 and 2 teslas respectively. The results for the wave electromagnetic field in the plasma chamber are displayed. They exhibit a strong enrichment of the poloidal mode number m-spectrum which leads to the upshift of the parallel wavenumber, {kappa}{perpendicular}, and to the wave absorption. The m-spectrum is bounded when the local poloidal wavenumber reaches the Alfven wavenumber and the {kappa}{perpendicular} upshifts do not destroy the wave directionality. Linear estimations of the driven current are made. The current density profiles are found to be peaked and we find that about 88 kA can be driven in the 1 tesla/1.7 keV phase with 1.7 MW coupled to the electrons. In the 2 tesla/3.4 keV case, 47 kA are driven with a total power of 1.5 MW, 44% of which are absorbed on the hydrogen minority, through the second harmonic ion cyclotron resonance. The global efficiency is then 0.18 {times} 10{sup 19} A m{sup {minus}2}W{sup {minus}1} if one considers only the effective power going to the electrons.

  17. Spatiotemporal Variations in Cloud-Top Momentum Flux of Convective Gravity Waves Including Nonlinear Forcing Effects

    NASA Astrophysics Data System (ADS)

    Kang, Min-Jee; Chun, Hye-Yeong; Preusse, Peter; Ern, Manfred

    2015-04-01

    Cloud-top momentum flux (CTMF) of a convective gravity wave (CGW) parameterization by Choi and Chun is calculated using the NCEP Climate Forecast System Reanalysis (CFSR) data during 7 years (2003-2009) with a horizontal resolution of 1° latitude x 1° longitude and an hourly temporal resolution. CGWs are generated by both diabatic forcing and nonlinear forcing, and in this study, two sets of CTMF are calculated considering CGW generated exclusively by diabatic forcing (DF) and by both forcing mechanisms (CTL). In DF, CTMF shows strong peak near the equator and winter extratropics in association with storm-track region, while in CTL, the total amount of CTMF is reduced compared with DF due to the cancellation between the diabatic forcing and nonlinear forcing. Nonlinear forcing effect is included in the CTMF calculation based on the nonlinearity factor (NF) of thermally induced internal gravity waves, which is determined by diabatic heating rate, wind, and stability in the convective region. NF is relatively large near the equator where major convection exists, and this can be one of factors to lead unexpected small values of GWMF near the equator, which has been revealed in recent reports of the satellite observations. For comparison with satellite observation, GWMF estimated from the HIRDLS observation is used during 2005-2007. In Asian Monsoon region, HIRDLS GWMF at z = 25 km shows clearly small values in 2006, while convective sources and CTMF are generally similar to the three years. To understand this result, CGW momentum flux at 25 km (CGWMF25) is estimated from CTMF, considering exclusively the critical-level filtering by the background wind from the cloud top to z = 25 km. CGWMF25 in 2006 is smaller than other two years in JJA equatorward of 10°, associated with different QBO phase that can filter out a large portion of the positive momentum flux of CTMF in the stratosphere. The QBO filtering effect is not evident poleward of 10°, and thus interannual

  18. Hexamethyldisiloxane-based nanoprobes for (1) H MRI oximetry.

    PubMed

    Gulaka, Praveen K; Rastogi, Ujjawal; McKay, Madalyn A; Wang, Xianghui; Mason, Ralph P; Kodibagkar, Vikram D

    2011-12-01

    Quantitative in vivo oximetry has been reported using (19) F MRI in conjunction with reporter molecules, such as perfluorocarbons, for tissue oxygenation (pO(2) ). Recently, hexamethyldisiloxane (HMDSO) has been proposed as a promising alternative reporter molecule for (1) H MRI-based measurement of pO(2) . To aid biocompatibility for potential systemic administration, we prepared various nanoemulsion formulations using a wide range of HMDSO volume fractions and HMDSO to surfactant ratios. Calibration curves (R(1) versus pO(2) ) for all emulsion formulations were found to be linear and similar to neat HMDSO for low surfactant concentrations (<10% v/v). A small temperature dependence in the calibration curves was observed, similar to previous reports on neat HMDSO, and was characterized to be approximately 1 Torr/ °C under hypoxic conditions. To demonstrate application in vivo, 100 µL of this nanoemulsion was administered to healthy rat thigh muscle (Fisher 344, n=6). Dynamic changes in mean thigh tissue pO(2) were measured using the PISTOL (proton imaging of siloxanes to map tissue oxygenation levels) technique in response to oxygen challenge. Changing the inhaled gas to oxygen for 30 min increased the mean pO(2) significantly (p<0.001) from 39 ± 7 to 275 ± 27 Torr. When the breathing gas was switched back to air, the tissue pO(2) decreased to a mean value of 45 ± 6 Torr, not significantly different from baseline (p>0.05), in 25 min. A first-order exponential fit to this part of the pO(2) data (i.e. after oxygen challenge) yielded an oxygen consumption-related kinetic parameter k=0.21 ± 0.04 min(-1) . These results demonstrate the feasibility of using HMDSO nanoemulsions as nanoprobes of pO(2) and their utility to assess oxygen dynamics in vivo, further developing quantitative (1) H MRI oximetry.

  19. Geomagnetic field variations induced by internal and surface waves in the four-layer model of the marine environment

    NASA Astrophysics Data System (ADS)

    Smagin, V. P.; Semkin, S. V.; Savchenko, V. N.

    2014-09-01

    The layered model of the marine environment, including the atmosphere, two seawater layers with different conductivity and density, and the bottom rock layer, has been considered. The geomagnetic field variations, generated by internal and surface waves with different frequency and propagation direction, have been found in the scope of this model. The effect of magnetic permeability and electric conductivity of bottom rocks on induced magnetic field has been taken into account. The transfer functions and spectral densities of these variations have been analytically determined and numerically estimated.

  20. Study of dynamical variation of particles and waves in the inner magnetosphere using ground-based network observations - PWING Project

    NASA Astrophysics Data System (ADS)

    Shiokawa, K.; Otsuka, Y.; Oyama, S. I.; Miyoshi, Y.; Nishitani, N.; Ozaki, M.; Kataoka, R.; Nose, M.; Seki, K.; Nose, M.

    2016-12-01

    Dynamical variation of particles and waves in the inner magnetosphere is one of the most important research topics in recent space physics. The inner magnetosphere contains plasmas in wide energy ranges from below electron volts to Mega-electron volts. These plasmas (electrons and ions) interact with ULF/ELF/VLF waves at frequencies of 0.1 Hz to 10 kHz to cause their energization in the equatorial plane of the magnetosphere and loss into the ionosphere. In order to provide global distribution and quantitative evaluation of the dynamical variation of plasmas and waves in the inner magnetosphere, we have started PWING Project (study of dynamical variation of Particles and Waves in the INner magnetosphere using Ground-based network observations, http://www.isee.nagoya-u.ac.jp/dimr/PWING/PWING_web_e.htm), which will last for 5 years from April 2016, as a Grant-in-Aid for Specially Promoted Research of the Japan Society for the Promotion of Science (JSPS). In the PWING project, we plan to construct a longitudinal observation network at 8 ground-based stations at subauroral latitudes (magnetic latitudes: 60 degree) to monitor 2-dimentional images of particle precipitation and ULF/ELF/VLF waves at frequencies from 0.1Hz to 10 kHz. We combine these longitudinal network observations with the ERG satellite, which will be launched in fiscal year 2016, and global modeling. Using these comprehensive observations and modeling, we provide global distribution and quantitative evaluation of the dynamical variation of plasmas and waves in the inner magnetosphere at L 4 Re near the plasmapause. The MeV-energy electrons in the inner magnetosphere forms the radiation belts around the Earth, which are continuous thread for space vehicles and human bodies in space. The outcome from the PWING Project will increase the accuracy of forecasting the variations of radiation belt particles in the inner magnetosphere and contribute to the safe operation of human activities in space. The results

  1. Effects of water depth and spectral bandwidth on Stokes drift estimation based on short-term variation of wave conditions

    NASA Astrophysics Data System (ADS)

    Myrhaug, Dag; Wang, Hong; Holmedal, Lars Erik

    2016-04-01

    The Stokes drift represents an important transport component of ocean circulation models. Locally it is responsible for transport of e.g. contaminated ballast water from ships, oil spills, plankton and larvae. It also plays an important role in mixing processes across the interphase between the atmosphere and the ocean. The Stokes drift is the mean Lagrangian velocity obtained from the water particle trajectory in the wave propagation direction; it is maximum at the surface, decreasing rapidly with the depth below the surface. The total mean mass transport is obtained by integrating the Stokes drift over the water depth; this is also referred to as the volume Stokes transport. The paper provides a simple analytical method which can be used to give estimates of the Stokes drift in moderate intermediate water depth based on short-term variation of wave conditions. This is achieved by using a joint distribution of individual wave heights and wave periods together with an explicit solution of the wave dispersion equation. The mean values of the surface Stokes drift and the volume Stokes transport for individual random waves within a sea state are presented, and the effects of water depth and spectral bandwidth parameter are discussed. Furthermore, example of results corresponding to typical field conditions are presented to demonstrate the application of the method, including the Stokes drift profile in the water column beneath the surface. Thus, the present analytical method can be used to estimate the Stokes drift in moderate intermediate water depth for random waves within a sea state based on available wave statistics.

  2. Construction and application of variations on the cylindrical gravitational waves of Weber, Wheeler, and Bonnor

    NASA Astrophysics Data System (ADS)

    Mishima, Takashi; Tomizawa, Shinya

    2017-07-01

    To clarify certain nonlinear properties of strong gravitational field, we investigate cylindrically symmetric gravitational waves that are localized as regular wave packets in the space of radial and time coordinates. The waves are constructed by applying a certain kind of harmonic mapping method to the seed solutions with linear polarization, which are generalizations of the solution representing a cylindrical gravitational pulse wave discussed by Weber, Wheeler, and Bonnor. The solutions obtained here, though their form is rather simple, show occurrence of strong mutual conversion between a linear mode and a cross mode apparently. The single localized wave shows the conversion in the vicinity of the symmetric axis where the self-interaction is strengthened, and the collision between multiple waves also causes the conversion. These phenomena can be thought to be the emergence of genuine nonlinearity that the Einstein gravity holds. Finally we discuss a simple, but interesting application of the solutions to the case of the Einstein-Maxwell system.

  3. Wave run up statistics on a meso-tidal, steeply-sloping beach: effect of wave forcing and tidal variations

    NASA Astrophysics Data System (ADS)

    Vousdoukas, M. I.; Kirupakaramoorthy, T.; Ferreira, O.

    2012-12-01

    Understanding the probability distributions of shoreline elevation, swash height and swash maxima is important for several applications like numerical modeling of dune erosion and stochastic modeling of swash zone processes. In the present contribution we analyze wave run-up time series obtained from a total of 456 timestack images and acquired, during a 2 years period, from a coastal video monitoring station installed at Faro Beach, S. Portugal. All transformations from image to world coordinates took place considering the daily beach topography measured during 40 RTK-DGPS surveys and the timestack images were processed in an open-access, freely-available Graphical User Interface software (Vousdoukas et al. 2012, Oc. Dyn., 62), developed to extract and process time-series of the cross-shore position of the swash extrema. The shoreline elevation probability distribution was found to be in good agreement with Rayleigh distribution, while comparisons with a standard normal PDF showed no statistically significant match. The Kumaraswamy distribution was found to reproduce even better the measured probability distributions. Following, the 456 swash series were separated into classes according to the significant wave height and water level, among others, and ensemble average distributions were generated for each 'bin'. Low wave height distributions were shown to be better represented by power-law PDFs and only more energetic conditions resulted in good match with the Rayleigh distribution. High tide series were characterized by lower kurtosis compared to low tide ones. The Kumaraswamy distribution (f(x)=pqxp-1(1-xp)q-1) was found to reproduce better all the probability distributions of the different cases, as it is a very versatile due to the 2 shape coefficients p, q. Preliminary results showed that it is possible to parameterize the 2 Kumaraswamy distribution shape coefficients as a function of the wave and tidal parameters (p=0.28Hs+0.27ηs; q=0.85Hs+1.16ηs), in

  4. Slave-boson mean-field theory versus variational-wave-function approach for the periodic Anderson model

    NASA Astrophysics Data System (ADS)

    Yang, Min-Fong; Sun, Shih-Jye; Hong, Tzay-Ming

    1993-12-01

    We show that a special kind of slave-boson mean-field approximation, which allows for the symmetry-broken states appropriate for a bipartite lattice, can give essentially the same results as those by the variational-wave-function approach proposed by Gula´csi, Strack, and Vollhardt [Phys. Rev. B 47, 8594 (1993)]. The advantages of our approach are briefly discussed.

  5. Variational approach to studying solitary waves in the nonlinear Schrödinger equation with complex potentials.

    PubMed

    Mertens, Franz G; Cooper, Fred; Arévalo, Edward; Khare, Avinash; Saxena, Avadh; Bishop, A R

    2016-09-01

    We discuss the behavior of solitary wave solutions of the nonlinear Schrödinger equation (NLSE) as they interact with complex potentials, using a four-parameter variational approximation based on a dissipation functional formulation of the dynamics. We concentrate on spatially periodic potentials with the periods of the real and imaginary part being either the same or different. Our results for the time evolution of the collective coordinates of our variational ansatz are in good agreement with direct numerical simulation of the NLSE. We compare our method with a collective coordinate approach of Kominis and give examples where the two methods give qualitatively different answers. In our variational approach, we are able to give analytic results for the small oscillation frequency of the solitary wave oscillating parameters which agree with the numerical solution of the collective coordinate equations. We also verify that instabilities set in when the slope dp(t)/dv(t) becomes negative when plotted parametrically as a function of time, where p(t) is the momentum of the solitary wave and v(t) the velocity.

  6. Reference values for pulse oximetry at high altitude

    PubMed Central

    Gamponia, M; Babaali, H; Yugar, F; Gilman, R

    1998-01-01

    OBJECTIVE—To determine reference values for oxygen saturation (SaO2) in healthy children younger than 5 years living at high altitude.
DESIGN—One hundred and sixty eight children were examined for SaO2 at 4018 m during well child visits. Physiological state was also noted during the examination.
RESULTS—The mean SaO2 was 87.3% (95% confidence intervals (CI) 86.7%, 87.9%) with a median value of 87.7%. A significant difference was observed in SaO2 between children younger than 1 year compared with older children, although the difference was no longer demonstrable when sleeping children were excluded.
CONCLUSIONS—This study has provided a reference range of SaO2 values for healthy children under 5 years old so that pulse oximetry may be used as an adjunct in diagnosing acute respiratory infections. Younger children were also shown to have a lower mean SaO2 than older children living at high altitude, which suggests physiological adaptation to high altitude over time. In addition, sleep had a lowering effect on SaO2, although the clinical importance of this remains undetermined.

 PMID:9659095

  7. The effect of nail polish on pulse oximetry readings.

    PubMed

    Hakverdioğlu Yönt, Gülendam; Akin Korhan, Esra; Dizer, Berna

    2014-04-01

    Pulse oximeters utilise the pulsatile nature of arterial blood flow to distinguish it from venous flow and estimate oxygen saturation in arterial blood. Pulse oximetry is primarily used in hospital wards, emergency rooms, intensive care units, operating rooms and home care. The objective of this study is to determine whether the use of nail polish of various colours have an effect on oximeter readings of oxygen saturation value. The sample group of this study is comprised of 40 healthy women. In the first phase of the study, readings were taken on left and right hand fingers, with no nail polish, to determine any differences in oxygen saturation value. In the second phase of the study, 10 different colours of nail polish, namely dark red, yellow, dark blue, green, purple, brown, white, metallic, black and pink, of the same brand were applied. Readings were recorded once oxygen saturation values on the screen became stable. Number and percentage distributions along with Wilcoxon signed ranks and Friedman test were used in the analysis of data. Only red nail polish did not yield statistically significant reading results. We conclude that different nail polish colours cause a clinically significant change in pulse oximeter readings in healthy volunteers. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Oximetry: recent insights into retinal vasopathies and glaucoma.

    PubMed

    Boeckaert, J; Vandewalle, E; Stalmans, I

    2012-01-01

    This review will highlight a new technology and recent insights into measuring retinal oxygen saturation in several ophthalmic diseases. A growing body of evidence suggests that disturbances in retinal blood flow and oxygenation are related to several retinopathies and glaucoma, which can severely impair vision. The retinal oximeter may allow researchers and physicians to gain deeper insights into retinal physiology and clarify the impact of ischemia on retinal health and function. There are two commercially available systems to measure retinal oxygen saturation: the Oxymap retinal oximeter (Reykjavik, Iceland) and the Imedos Systems UG (Jena, Germany). In this review we will focus on the results obtained with Oxymap. Direct and non-invasive measurement of retinal oxygen saturation have potentially useful diagnostic and therapeutic indications in various eye diseases such as diabetic retinopathy, age-related macular degeneration, central retinal vein and artery occlusion, anterior ischemic optic neuropathy and retinopathy of prematurity. Despite several limitations, oxygen saturation assessment in the retinal vessels is a significant advancement in the understanding of ocular diseases. Nevertheless, further studies are needed to validate the use of oximetry in retinal vasopathies and glaucoma.

  9. Indexes of aortic pressure augmentation markedly underestimate the contribution of reflected waves toward variations in aortic pressure and left ventricular mass.

    PubMed

    Booysen, Hendrik L; Woodiwiss, Angela J; Sibiya, Moekanyi J; Hodson, Bryan; Raymond, Andrew; Libhaber, Elena; Sareli, Pinhas; Norton, Gavin R

    2015-03-01

    Although indexes of wave reflection enhance risk prediction, the extent to which measures of aortic systolic pressure augmentation (augmented pressures [Pa] or augmentation index) underestimate the effects of reflected waves on cardiovascular risk is uncertain. In participants from a community sample (age >16), we compared the relative contribution of reflected (backward wave pressures and the reflected wave index [RI]) versus augmented (Pa and augmentation index) pressure wave indexes to variations in central aortic pulse pressure (PPc; n=1185), and left ventricular mass index (LVMI; n=793). Aortic hemodynamics and LVMI were determined using radial applanation tonometry (SphygmoCor) and echocardiography. Independent of confounders, RI and backward wave pressures contributed more than forward wave pressures, whereas Pa and augmentation index contributed less than incident wave pressure to variations in PPc (P<0.0001 for comparison of partial r values). In those <50 years of age, while backward wave pressures (partial r=0.28, P<0.0001) contributed more than forward wave pressures (partial r=0.15, P<0.001; P<0.05 for comparison of r values), Pa (partial r=0.13, P<0.005) contributed to a similar extent as incident wave pressure (partial r=0.22, P<0.0001) to variations in LVMI. Furthermore, in those ≥50 years of age, backward wave pressures (partial r=0.21, P<0.0001), but not forward wave pressures (P=0.98), while incident wave pressure (partial r=0.23, P<0.0001), but not Pa (P=0.80) were associated with LVMI. Pa and augmentation index underestimated the effect of wave reflection on PPc and LVMI in both men and women. Thus, as compared with relations between indexes of aortic pressure augmentation and PPc or LVMI, strikingly better relations are noted between aortic wave reflection and PPc or LVMI. © 2014 American Heart Association, Inc.

  10. Effect of oximetry on hospitalization in bronchiolitis: a randomized clinical trial.

    PubMed

    Schuh, Suzanne; Freedman, Stephen; Coates, Allan; Allen, Upton; Parkin, Patricia C; Stephens, Derek; Ungar, Wendy; DaSilva, Zelia; Willan, Andrew R

    2014-08-20

    Routine use of pulse oximetry has been associated with changes in bronchiolitis management and may have lowered the hospitalization threshold for patients with bronchiolitis. To examine if infants with bronchiolitis whose displayed oximetry measurements have been artificially elevated 3 percentage points above true values experience hospitalization rates at least 15% lower compared with infants with true values displayed. Randomized, double-blind, parallel-group trial conducted from 2008 to 2013 in a tertiary-care pediatric emergency department in Toronto, Ontario, Canada. Participants were 213 otherwise healthy infants aged 4 weeks to 12 months with mild to moderate bronchiolitis and true oxygen saturations of 88% or higher. Pulse oximetry measurements with true saturation values displayed or with altered saturation values displayed that have been increased 3 percentage points above true values. The primary outcome was hospitalization within 72 hours, defined as inpatient admission within this interval or active hospital care for greater than 6 hours. Secondary outcomes included the use of supplemental oxygen in the emergency department, level of physician agreement with discharge from the emergency department, length of emergency department stay, and unscheduled visits for bronchiolitis within 72 hours. Forty-four of 108 patients (41%) in the true oximetry group and 26 of 105 (25%) in the altered oximetry group were hospitalized within 72 hours (difference, 16% [95% CI for the difference, 3.6% to 28.4%]; P = .005). Using the emergency department physician as a random effect, the primary treatment effect remained significant (adjusted odds ratio, 4.0 [95% CI, 1.6 to 10.5]; P = .009). None of the secondary outcomes were significantly different between the groups. There were 23 of 108 (21.3%) subsequent unscheduled medical visits for bronchiolitis in the true oximetry group and 15 of 105 (14.3%) in the altered oximetry group (difference, 7% [95% CI, -0.3% to 0

  11. Pulse oximetry as a screening tool for detecting major congenital heart defects in Indian newborns.

    PubMed

    Saxena, Anita; Mehta, Anurag; Ramakrishnan, Sivasubramanian; Sharma, Mamta; Salhan, Sudha; Kalaivani, M; Juneja, Rajnish

    2015-09-01

    To evaluate the use of pulse oximetry as a screening tool for detecting major congenital heart defects (CHDs) in Indian newborns. Cross-sectional observational study. In a community hospital of north India, babies born during a specific 8 h period of the day were recruited over a period of 3 years. Newborns with incomplete documentation were excluded. Routine clinical examination, pulse oximetry and bedside echocardiography. Any abnormalities in clinical examination and pulse oximetry were recorded. CHDs were diagnosed using bedside echocardiography. Accuracy of pulse oximetry, clinical examination and their combination for detecting major CHDs was calculated. Among the 19 009 newborns screened, 70 had major CHDs at birth (44 serious, 26 critical). Pulse oximetry detected 39 major (sensitivity 55.7%, 95% CI 44.1% to 66.8%; specificity 68.3%, 67.6% to 68.9%) and 22 critical CHDs (sensitivity 84.6%, 66.5% to 93.9%; specificity 68.3%, 67.6% to 68.9%). Addition of pulse oximetry to clinical examination significantly improved sensitivity for major CHDs (35.7% (25.5% to 47.4%) to 75.7% (64.5% to 85.3%), p<0.01) and critical CHDs (11.5% (4.0% to 29.0%) to 84.6% (66.5% to 93.9%), p<0.01). Pulse oximetry is a sensitive screening tool for detecting major CHDs in Indian newborns. It adds significant value to the current practice of using clinical examination as a sole screening tool for detecting major CHDs. However, specificity of pulse oximetry was much lower in our study. Possible reasons for low specificity could be non-repetition of pulse oximetry in newborns with initial lower saturations, high prevalence of infections and respiratory issues in our cohort and use of non-motion tolerant oximeter. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  12. Variation.

    ERIC Educational Resources Information Center

    Hamilton City Board of Education (Ontario).

    Suggestions for studying the topic of variation of individuals and objects (balls) to help develop elementary school students' measurement, comparison, classification, evaluation, and data collection and recording skills are made. General suggestions of variables that can be investigated are made for the study of human variation. Twelve specific…

  13. Enamel nail polish does not interfere with pulse oximetry among normoxic volunteers.

    PubMed

    Brand, Thomas M; Brand, Mary E; Jay, Gregory D

    2002-02-01

    To determine if enamel nail polish interferes with pulse oximetry. Laboratory investigation. 12 healthy nonsmoking volunteers. Spectrophotometry was performed on polystyrene cuvettes painted with 3 uniform layers of nail polish enamel in triplicate. Absorbances were compared at 660 and 940 nm for 10 colors across the visible spectrum and documented by the Institute of Electrical and Electronic Engineers color code against Pantone matches on a color scanner. Colors were then selected that had the greatest A660-A940 difference and pulse oximetry (Nellcor N-209A. Pleasanton , CA) was performed on nails painted with these colors on 12 subjects using an unpainted digit as a control. When tested by the oximeter, there were no SpO2 differences detected between nail polish colors, nor were there any differences between the painted and the unpainted control digits across subjects (F = 0.51, ANOVA; p = 0.67). Blue (B), green (G), and lime green (G') possessed the largest A660-A940 difference and potentially could interfere with pulse oximetry but did not do so in the clinical model. Enamel finger nail polish pigments do not interfere with pulse oximetry as previously reported, the A660-A940 difference must be greater than 1.88 +/- 0.23 SD AU in order to affect pulse oximetry.

  14. The seasonal variation of the D region as inferred from propagation characteristics of LF radio waves

    NASA Technical Reports Server (NTRS)

    Ishimine, T.; Ishii, T.; Echizenya, Y.

    1985-01-01

    The propagation data of JG2AS 40 kHz (Japanese Standard Frequency), Loran C 100 kHz radio waves, and meteorological data were analyzed to study the association of propagation characteristics of LF radio waves with the atmospheric circulation in the mesosphere. The monthly averaged electric fields were depicted on the complex plane for typical summer and winter months, June and November. The locus traced out by the electric field vector during daytime is nearly circular. This is because during daytime the amplitude of the sky wave remains nearly constant while its phase changes in accord with the height change of the reflection layer, and thus the electric field vector traces out a circular locus with its center at the tip of the supposed ground wave vector. The locus has a loop during the sunrise or sunset period, which seems to arise from interference of two waves reflected by two different layers. In June the amplitude of the sky wave decreases rapidly before the dawn or increases after the dusk. In November such rapid change is not observed. During nighttime, the sky wave phase changes in such a way as to suggest that the reflection height moves upwards with time before midnight or lowers after midnight in November. In June it changes similarly before midnight, but after midnight it varies erratically. These characteristics are closely related to the structure of the D region, which is clearly shown by simulating the loci traced out by electric fields.

  15. Pulse Wave Variation during the Menstrual Cycle in Women with Menstrual Pain

    PubMed Central

    Jeon, Soo Hyung; Kim, Kyu Kon; Lee, In Seon; Lee, Yong Tae; Kim, Gyeong Cheol; Chi, Gyoo Yong; Cho, Hye Sook; Kang, Hee Jung

    2016-01-01

    Objective. This study is performed to obtain objective diagnostic indicators associated with menstrual pain using pulse wave analysis. Methods. Using a pulse diagnostic device, we measured the pulse waves of 541 women aged between 19 and 30 years, placed in either an experimental group with menstrual pain (n = 329) or a control group with little or no menstrual pain (n = 212). Measurements were taken during both the menstrual and nonmenstrual periods, and comparative analysis was performed. Results. During the nonmenstrual period, the experimental group showed a significantly higher value in the left radial artery for the radial augmentation index (RAI) (p = 0.050) but significantly lower values for pulse wave energy (p = 0.021) and time to first peak from baseline (T1) (p = 0.035) in the right radial artery. During the menstrual period, the experimental group showed significantly lower values in the left radial artery for cardiac diastole and pulse wave area during diastole and significantly higher values for pulse wave area during systole, ratio of systolic phase to the full heartbeat, and systolic-diastolic ratio. Conclusion. We obtained indicators of menstrual pain in women during the menstrual period, including prolonged systolic and shortened diastolic phases, increases in pulse wave energy and area of representative pulse wave, and increased blood vessel resistance. PMID:27579304

  16. Pulse Wave Variation during the Menstrual Cycle in Women with Menstrual Pain.

    PubMed

    Jeon, Soo Hyung; Kim, Kyu Kon; Lee, In Seon; Lee, Yong Tae; Kim, Gyeong Cheol; Chi, Gyoo Yong; Cho, Hye Sook; Kang, Hee Jung; Kim, Jong Won

    2016-01-01

    Objective. This study is performed to obtain objective diagnostic indicators associated with menstrual pain using pulse wave analysis. Methods. Using a pulse diagnostic device, we measured the pulse waves of 541 women aged between 19 and 30 years, placed in either an experimental group with menstrual pain (n = 329) or a control group with little or no menstrual pain (n = 212). Measurements were taken during both the menstrual and nonmenstrual periods, and comparative analysis was performed. Results. During the nonmenstrual period, the experimental group showed a significantly higher value in the left radial artery for the radial augmentation index (RAI) (p = 0.050) but significantly lower values for pulse wave energy (p = 0.021) and time to first peak from baseline (T1) (p = 0.035) in the right radial artery. During the menstrual period, the experimental group showed significantly lower values in the left radial artery for cardiac diastole and pulse wave area during diastole and significantly higher values for pulse wave area during systole, ratio of systolic phase to the full heartbeat, and systolic-diastolic ratio. Conclusion. We obtained indicators of menstrual pain in women during the menstrual period, including prolonged systolic and shortened diastolic phases, increases in pulse wave energy and area of representative pulse wave, and increased blood vessel resistance.

  17. The seasonal variation of the D region as inferred from propagation characteristics of LF radio waves

    NASA Technical Reports Server (NTRS)

    Ishimine, T.; Ishii, T.; Echizenya, Y.

    1985-01-01

    The propagation data of JG2AS 40 kHz (Japanese Standard Frequency), Loran C 100 kHz radio waves, and meteorological data were analyzed to study the association of propagation characteristics of LF radio waves with the atmospheric circulation in the mesosphere. The monthly averaged electric fields were depicted on the complex plane for typical summer and winter months, June and November. The locus traced out by the electric field vector during daytime is nearly circular. This is because during daytime the amplitude of the sky wave remains nearly constant while its phase changes in accord with the height change of the reflection layer, and thus the electric field vector traces out a circular locus with its center at the tip of the supposed ground wave vector. The locus has a loop during the sunrise or sunset period, which seems to arise from interference of two waves reflected by two different layers. In June the amplitude of the sky wave decreases rapidly before the dawn or increases after the dusk. In November such rapid change is not observed. During nighttime, the sky wave phase changes in such a way as to suggest that the reflection height moves upwards with time before midnight or lowers after midnight in November. In June it changes similarly before midnight, but after midnight it varies erratically. These characteristics are closely related to the structure of the D region, which is clearly shown by simulating the loci traced out by electric fields.

  18. Low signal quality pulse oximetry measurements in newborn infants are reliable for oxygen saturation but underestimate heart rate.

    PubMed

    Narayen, Ilona C; Smit, Marrit; van Zwet, Erik W; Dawson, Jennifer A; Blom, Nico A; te Pas, Arjan B

    2015-04-01

    We assessed the influence of system messages (SyMs) on oxygen saturation (SpO2 ) and heart rate measurements after birth to see whether clinical decision-making changed if clinicians included SyM data. The heart rate and SpO2 of term infants were recorded using Masimo pulse oximeters. Differences in means and standard deviations (SD) were calculated. Permutation corrected the nonrandom distribution and intersubject variation. SpO2 and heart rate centile charts were computed with, and without, SyMs. Pulse oximetry measurements from 117 neonates provided 28 477 data points. SyMs occurred in 46% of measurements. Low signal quality accounted for 99.9% of SyMs. The mean SpO2 was lower with SyMs (p < 0.001), while the SpO2 SD was similar to data without SyMs. The SpO2 centile charts were approximately 2% lower with SyMs included, but they were not more dispersed. Mean heart rate was lower (p < 0.001) and more dispersed (p < 0.001) when a SyM occurred. The heart rate centile charts were lower, with increased variability, when SyMs were included. A SyM occurred frequently during pulse oximetry in term infants after birth. SpO2 measurements with low signal quality proved reliable for monitoring an infant's clinical condition. However, heart rate could be underestimated by low signal quality measurements. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  19. Variational Estimation of Wave-affected Parameters in a Two-equation Turbulence Model

    DTIC Science & Technology

    2014-01-01

    wave breaking on modeling the trajectories of drifters in the northern 20 Adriatic Sea during a wind event. Ocean Modelling, 30, 225-239. 21 33 Chu...enhanced greatly near the sea surface due to increasing shear by 4 surface gravity waves under non-breaking (including Langmuir circulation) and 5...from the sea surface), which is twice faster than the classical wall layer 20 dissipation. The second layer is the transition layer below the breaking

  20. Variation of Langmuir wave polarization with electron beam speed in type III radio bursts

    SciTech Connect

    Malaspina, David M.; Cairns, Iver H.; Ergun, Robert E.

    2013-06-13

    Observations by the twin STEREO spacecraft of in-situ electric field waveforms and radio signatures associated with type III radio bursts have demonstrated that the polarization of electron beam-driven waves near the local plasma frequency depends strongly on the speed of the driving electron beam. We expand upon a previous study by including all radio bursts with in-situ waveforms observed by STEREO in 2011. The expanded data set contains five times more radio bursts (35 up from 7) and three times as many Langmuir waves (663 up from 168). While this expanded study supports the results of the original study, that faster (slower) beam electrons drive waves with strong (weak) electric fields perpendicular to the local magnetic field, the larger data set emphasizes that the observation of strong perpendicular electric fields at high electron beam speeds is probabilistic rather than definite. This property supports the interpretation of wave polarization dependence on beam speed as Langmuir/z-mode waves shifted to small wave number through interaction with turbulent solar wind density fluctuations.

  1. Variational Optimization of the Second-Order Density Matrix Corresponding to a Seniority-Zero Configuration Interaction Wave Function.

    PubMed

    Poelmans, Ward; Van Raemdonck, Mario; Verstichel, Brecht; De Baerdemacker, Stijn; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Alcoba, Diego R; Bultinck, Patrick; Van Neck, Dimitri

    2015-09-08

    We perform a direct variational determination of the second-order (two-particle) density matrix corresponding to a many-electron system, under a restricted set of the two-index N-representability P-, Q-, and G-conditions. In addition, we impose a set of necessary constraints that the two-particle density matrix must be derivable from a doubly occupied many-electron wave function, i.e., a singlet wave function for which the Slater determinant decomposition only contains determinants in which spatial orbitals are doubly occupied. We rederive the two-index N-representability conditions first found by Weinhold and Wilson and apply them to various benchmark systems (linear hydrogen chains, He, N2, and CN(-)). This work is motivated by the fact that a doubly occupied many-electron wave function captures in many cases the bulk of the static correlation. Compared to the general case, the structure of doubly occupied two-particle density matrices causes the associate semidefinite program to have a very favorable scaling as L(3), where L is the number of spatial orbitals. Since the doubly occupied Hilbert space depends on the choice of the orbitals, variational calculation steps of the two-particle density matrix are interspersed with orbital-optimization steps (based on Jacobi rotations in the space of the spatial orbitals). We also point to the importance of symmetry breaking of the orbitals when performing calculations in a doubly occupied framework.

  2. Limitations of oximetry to measure heart rate variability measures.

    PubMed

    Lu, Guohua; Yang, Fang

    2009-09-01

    Measuring heart rate variability (HRV) is widely used to assess autonomic nervous system function. It requires accurate measurement of the interval between successive heartbeats. This can be achieved from recording the electrocardiogram (ECG), which is non-invasive and widely available. However, methodological problems inherent in recording and analyzing ECG traces have motivated a search for alternative means of measuring the interval between successive heartbeats. Recording blood oxygenation pulsations (photoplethysmography-PPG) is also convenient, non-invasive and widely available, and has been suggested as an effective alternative to ECG to derive HRV. Moreover, it has been claimed that the pulse waveforms produced by oximetry may be more practicable than R-R intervals measured from the by ECG, especially for ambulatory recordings. We have therefore compared PPG with ECG recordings to measure HRV applying the same signal analysis techniques to PPG and ECG recordings made simultaneously. Comparison of 5 min recording epochs demonstrated a very high degree of correlation, in temporal, frequency domains and non-linear analysis, between HRV measures derived from the PPG and ECG. However, we found that the PPG signal is especially vulnerable to motion artifacts when compared to the ECG, preventing any HRV analysis at all in a significant minority of PPG recordings. Our results demonstrate that even though PPG provides accurate interpulse intervals to measure heart rate variability under ideal conditions, it is less reliable due to its vulnerability to motion artifacts. Therefore it is unlikely to prove a practical alternative to the ECG in ambulatory recordings or recordings made during other activities.

  3. Retinal oximetry in patients with ischaemic retinal diseases.

    PubMed

    Rilvén, Sandra; Torp, Thomas Lee; Grauslund, Jakob

    2017-03-01

    The retinal oximeter is a new tool for non-invasive measurement of retinal oxygen saturation in humans. Several studies have investigated the associations between retinal oxygen saturation and retinal diseases. In the present systematic review, we examine whether there are associations between retinal oxygen saturation and retinal ischaemic diseases. We used PubMed and Embase to search for retinal oxygen saturation and retinal ischaemic diseases. Three separate searches identified a total of 79 publications. After two levels of manual screening, 10 studies were included: six about diabetic retinopathy (DR) and four about retinal vein occlusion. No studies about retinal artery occlusion were included. In diabetes, all studies found that increases in retinal venous oxygen saturation (rvSatO2 ) were associated with present as well as increasing levels of DR. Four of six studies also found increased retinal arterial oxygen saturation (raSatO2 ) in patients with DR. In patients with central retinal vein occlusion (CRVO), all studies found that rvSatO2 was reduced, but raSatO2 remained unchanged. Branch retinal vein occlusion was not associated with changes in retinal oxygen saturation, but this was based on a single study. In conclusion, DR is associated with increased rvSatO2 and might also be related to increased raSatO2 . Central retinal vein occlusion (CRVO) is correlated with increased rvSatO2 but unrelated to raSatO2 . Prospective studies are needed to expand these findings. These would tell whether retinal oximetry could be a potential tool for screening or a biomarker of treatment outcome in patients with ischaemic retinal diseases.

  4. Accuracy of noninvasive haemoglobin measurement by pulse oximetry depends on the type of infusion fluid.

    PubMed

    Bergek, Christian; Zdolsek, Joachim H; Hahn, Robert G

    2012-12-01

    Measurement of blood haemoglobin concentration by pulse oximetry could be of value in determining when erythrocytes should be transfused during surgery, but the effect of infusion fluids on the results is unclear. To study the effect of crystalloid and colloid fluid on the accuracy (bias) and precision of pulse oximetry haemoglobin estimation to indicate the venous haemoglobin concentration in volunteers. Open interventional crossover study. Single university hospital. Ten male volunteers aged 18-28 (mean 22) years. Each volunteer underwent three infusion experiments on separate days and in random order. The infusions were Ringer's acetate (20 ml kg), hydroxyethyl starch 130/0.4 (10 ml kg) and a combination of both. At the end of the infusions of Ringer's acetate, pulse oximetry haemoglobin concentration had decreased more than the true haemoglobin concentration (15 vs. 8%; P < 0.005; n = 10) whereas starch solution decreased pulse oximetry haemoglobin concentration less than true haemoglobin concentration (7 vs. 11%; P < 0.02; n = 20). The same differences were seen when the fluids were infused separately and when they were combined. The overall difference between all 956 pairs of pulse oximetry haemoglobin concentration and true haemoglobin concentrations (the bias) averaged only -0.7 g l whereas the 95% prediction interval was wide, ranging from -24.9 to 23.7 g l. In addition to the choice of infusion fluid, the bias was strongly dependent on the volunteer (each factor, P < 0.001). The bias of measuring haemoglobin concentration by pulse oximetry is dependent on whether a crystalloid or a colloid fluid is infused. Trial registration ClinicalTrials identifier: NCT01195025.

  5. During economic crisis can sleep questionnaires improve the value of oximetry for assessing sleep apnea?

    PubMed Central

    Pataka, Athanasia; Hohenforst-Schmidt, Wolfgang; Tsiouda, Theodora; Tsavlis, Drosos; Kioumis, Ioannis; Papakala, Elene; Karapantzos, Ilias; Karapantzou, Chrysa; Rapti, Aggeliki; Tsakiridis, Kosmas; Zarogoulidis, Konstantinos; Argyropoulou, Parakevi

    2016-01-01

    Background The diagnosis of obstructive sleep apnea/hypopnea syndrome (OSAHS) is essential but polysomnography (PSG) is expensive and time consuming. Oximetry has been used as a less expensive indicator of OSAHS. The aim of the study was to evaluate the clinical utility of the combination of oximetry with four different questionnaires: Stop, Stop Bang (S-B), Berlin questionnaire (BQ), Epworth Sleepiness Scale (ESS) in order to identify patients at risk for OSAHS compared with in-laboratory PSG. Methods Patients visiting a sleep clinic were prospectively studied. They completed Stop, S-B, BQ and ESS. Home oximetry and in laboratory PSG were performed within 3–20 days. Results A total of 204 patients were included in the study (77.5% males, mean age 51.8±13.8 years, BMI 32.8±6.2 kg/m2, SaO2% awake 95.7±2). S-B had the highest sensitivity (Se) (97.5%) and negative predictive value (NPV) (62.5%) but the lowest specificity (Sp) (9%), whereas ESS had the best Sp (75%) and positive predictive values (PPV) (81.4%). The predictive values of questionnaires improved as the severity of OSAHS worsened. The predictive values of oximetry were high for severe but low for mild and moderate OSAHS. For that oximetry was combined with different sleep questionnaires in different OSAHS severity groups, but with no improvement in the predictive values. Conclusions Oximetry may be used as a tool for identifying severe OSAHS. For mild and moderate disease the combination of questionnaires did not improve the diagnostic accuracy and especially for symptomatic patients with negative results, the need of PSG is essential. PMID:27999777

  6. Predicting blood transfusion using automated analysis of pulse oximetry signals and laboratory values.

    PubMed

    Shackelford, Stacy; Yang, Shiming; Hu, Peter; Miller, Catriona; Anazodo, Amechi; Galvagno, Samuel; Wang, Yulei; Hartsky, Lauren; Fang, Raymond; Mackenzie, Colin

    2015-10-01

    Identification of hemorrhaging trauma patients and prediction of blood transfusion needs in near real time will expedite care of the critically injured. We hypothesized that automated analysis of pulse oximetry signals in combination with laboratory values and vital signs obtained at the time of triage would predict the need for blood transfusion with accuracy greater than that of triage vital signs or pulse oximetry analysis alone. Continuous pulse oximetry signals were recorded for directly admitted trauma patients with abnormal prehospital shock index (heart rate [HR] / systolic blood pressure) of 0.62 or greater. Predictions of blood transfusion within 24 hours were compared using Delong's method for area under the receiver operating characteristic (AUROC) curves to determine the optimal combination of triage vital signs (prehospital HR + systolic blood pressure), pulse oximetry features (40 waveform features, O2 saturation, HR), and laboratory values (hematocrit, electrolytes, bicarbonate, prothrombin time, international normalization ratio, lactate) in multivariate logistic regression models. We enrolled 1,191 patients; 339 were excluded because of incomplete data; 40 received blood within 3 hours; and 14 received massive transfusion. Triage vital signs predicted need for transfusion within 3 hours (AUROC, 0.59) and massive transfusion (AUROC, 0.70). Pulse oximetry for 15 minutes predicted transfusion more accurately than triage vital signs for both time frames (3-hour AUROC, 0.74; p = 0.004) (massive transfusion AUROC, 0.88; p < 0.001). An algorithm including triage vital signs, pulse oximetry features, and laboratory values improved accuracy of transfusion prediction (3-hour AUROC, 0.84; p < 0.001) (massive transfusion AUROC, 0.91; p < 0.001). Automated analysis of triage vital signs, 15 minutes of pulse oximetry signals, and laboratory values predicted use of blood transfusion during trauma resuscitation more accurately than triage vital signs or pulse

  7. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    NASA Astrophysics Data System (ADS)

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-11-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common medical device. Pulse oximeters are ubiquitous in clinical environments; many people who have undergone surgery or visited a hospital environment have experienced the use of this device, making it a good candidate for an investigative lab. The experiment elicits the creative process of device development from students as they conduct measurements using a blood analog that reconstructs the principles of pulse oximetry.

  8. Estimation of temporal variations in the magnetic field arising from the motional induction that accompanies seismic waves at a large distance from the epicentre

    NASA Astrophysics Data System (ADS)

    Yamazaki, Ken'ichi

    2012-09-01

    Temporal variations in the electromagnetic field that accompany earthquakes are generated by various mechanisms, of which this study focuses on variations in the magnetic field arising from motionally induced electric currents that accompany seismic waves at large distances (several hundred kilometres) from the epicentre. A simple situation is considered in which seismic waves are approximated by plane waves and the electrical conductivity of the Earth's crust has a stratified structure. Solutions of Maxwell's equations corresponding to this situation have analytical expressions. Analysis of the solutions verifies that SH waves do not generate variations in the EM field above the ground surface, thereby implying that Rayleigh waves are dominant at a significant distance from earthquake epicentres. Numerical examples demonstrate that the amplitudes of the variations in the magnetic field monotonically increase with increasing conductivity, although attenuation because of the skin effect cannot be ignored. The amplitudes of the generated magnetic field can be sensitive to the conductivity of both the shallow and deep crust. Nevertheless, calculations assuming a simplified conductivity structure provide an upper limit to the possible amplitudes of variations in the magnetic field because of seismic waves. For example, the amplitudes of variations in the magnetic field arising from a Rayleigh wave with displacement amplitude of 10 cm and a period of 30 s are as large as 0.1 nT, close to the limit of detection under typical observation conditions. It is also suggested that phase differences between seismic ground motions and variations in the magnetic field are insignificantly influenced by details of conductivity structures, and they occur within a rather narrow range of values determined by the direction orientation of the ambient geomagnetic field. In the future, if a detection limit of 0.01 nT becomes available, phase difference may be used to distinguish variations

  9. Measurement and modeling of three-dimensional sound intensity variations due to shallow-water internal waves.

    PubMed

    Badiey, Mohsen; Katsnelson, Boris G; Lynch, James F; Pereselkov, Serguey; Siegmann, William L

    2005-02-01

    Broadband acoustic data (30-160 Hz) from the SWARM'95 experiment are analyzed to investigate acoustic signal variability in the presence of ocean internal waves. Temporal variations in the intensity of the received signals were observed over periods of 10 to 15 min. These fluctuations are synchronous in depth and are dependent upon the water column variability. They can be explained by significant horizontal refraction taking place when the orientation of the acoustic track is nearly parallel to the fronts of the internal waves. Analyses based on the equations of vertical modes and horizontal rays and on a parabolic equation in the horizontal plane are carried out and show interesting frequency-dependent behavior of the intensity. Good agreement is obtained between theoretical calculations and experimental data.

  10. Magnetosphere boundary observations along the Imp 7 orbit. I - Boundary locations and wave level variations

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Frank, L. A.; Lepping, R. P.

    1977-01-01

    The paper is concerned with magnetosphere boundary phenomena observed by the Imp 7 magnetic field, plasma, and plasma wave instruments in 1972 and 1973. Boundary locations for a 15-month period are surveyed, and the different types of crossings are described. The spacecraft crosses the dawn and dusk boundaries near 25 earth radii downstream, and the physical processes at the Imp 7 magnetopause appear to be intermediate between those observed over the poles and those observed at the lunar orbit. The Imp 7 orbit also traverses a downstream region near where 'fireball' phenomena occur. Electromagnetic wave modes detected in the broad low-frequency channel of the wave instrument are analyzed, and the interpretation of data of this type suggests that the broad low-frequency channel is sensitive to oscillations in the lower hybrid resonance region of the spectrum.

  11. Improved techniques for outgoing wave variational principle calculations of converged state-to-state transition probabilities for chemical reactions

    NASA Technical Reports Server (NTRS)

    Mielke, Steven L.; Truhlar, Donald G.; Schwenke, David W.

    1991-01-01

    Improved techniques and well-optimized basis sets are presented for application of the outgoing wave variational principle to calculate converged quantum mechanical reaction probabilities. They are illustrated with calculations for the reactions D + H2 yields HD + H with total angular momentum J = 3 and F + H2 yields HF + H with J = 0 and 3. The optimization involves the choice of distortion potential, the grid for calculating half-integrated Green's functions, the placement, width, and number of primitive distributed Gaussians, and the computationally most efficient partition between dynamically adapted and primitive basis functions. Benchmark calculations with 224-1064 channels are presented.

  12. A statistical study of variations of internal gravity wave energy characteristics in meteor zone

    NASA Technical Reports Server (NTRS)

    Gavrilov, N. M.; Kalov, E. D.

    1987-01-01

    Internal gravity wave (IGW) parameters obtained by the radiometer method have been considered by many other researchers. The results of the processing of regular radiometeor measurements taken during 1979 to 1980 in Obninsk (55.1 deg N, 36.6 deg E) are presented.

  13. Latitudinal variations in Kelvin wave activity in the MLT region over Indian subcontinent

    NASA Astrophysics Data System (ADS)

    Niranjan Kumar, Kondapalli

    2012-07-01

    A. Taori1, S. Sathishkumar3, V. Kamalakar2, R. Ghodpage4, S. Gurubaran3, P. T. Patil4 and S. V. B. Rao2 1. National Atmospheric Research Laboratory, Gadanki, India-517112. 2. Sri Venkateswara University, Tirupati, India-517502. 3. Equatorial Geophysical Research Laboratory, Tirunelveli, India-627001. 4. Indian Institute of Geomagnetism, Shivaji University, Kolhapur, India-416004. We investigate latitudinal behavior of planetary waves with the periods ranging from 3 to 5 days, which are generally known as ultra-fast Kelvin (UFK) wave. UFK waves are eastward propagating planetary waves, capable of penetrating into the thermosphere-ionosphere system and in-turn modulate phenomena occurring at those altitudes. Also UFK waves have been suggested to play an important role in driving the Intraseasonal Oscillations (ISOs) that are observed in the zonal mean temperatures and winds at low latitude Mesosphere and Lower Thermosphere (MLT) regions. In the absence of the mean wind shear, the Kelvin waves are expected to have a Gaussian structure with maximum amplitudes over equator in the observed zonal wind, temperature, vertical velocity and pressure, and decay with latitude exponentially. However, in a realistic atmosphere this may not happen and hence it is important to study the latitudinal structure of these waves. In present study, simultaneous observations of horizontal wind velocity, at 80-98 km altitudes, in the MLT region, measured with two medium frequency (MF) radars one at Tirunelveli (8.7N, 77.8E) and other at Kolhapur (16.8N, 74.2E), are utilized to delineate the latitudinal properties of Kelvin waves during the winter time of 2009, a year of solar minimum. We also analyze the temperature in stratosphere and mesosphere obtained from the Rayleigh lidar located at Gadanki (13.45N, 79.2E) and TIMED/SABER satellite measurements during the same period. In addition, the present study also makes use of simultaneous MST radar observations of horizontal winds located at

  14. Mountain wave-induced variations of ozone and total nitrogen dioxide contents over the Subpolar Urals

    NASA Astrophysics Data System (ADS)

    Kozhevnikov, V. N.; Elansky, N. F.; Moiseenko, K. B.

    2017-08-01

    Wavy spatial variations in the contents of trace gases are identified using plane measurements of O3 concentrations in the medium troposphere and the total content (TC) of NO2 in the atmospheric column from flights above the Subpolar Urals in April 1984. The results of model calculations allow us to relate these variations to mesoscale atmospheric disturbances above the mountains, which are caused by the influence of dynamic relief on the leaked-in flow.

  15. Spin-label oximetry at Q- and W-band

    NASA Astrophysics Data System (ADS)

    Subczynski, W. K.; Mainali, L.; Camenisch, T. G.; Froncisz, W.; Hyde, J. S.

    2011-04-01

    Spin-lattice relaxation times ( T1s) of small water-soluble spin-labels in the aqueous phase as well as lipid-type spin-labels in membranes increase when the microwave frequency increases from 2 to 35 GHz (Hyde, et al., J. Phys. Chem. B 108 (2004) 9524-9529). The T1s measured at W-band (94 GHz) for the water-soluble spin-labels CTPO and TEMPONE (Froncisz, et al., J. Magn. Reson. 193 (2008) 297-304) are, however, shorter than when measured at Q-band (35 GHz). In this paper, the decreasing trends at W-band have been confirmed for commonly used lipid-type spin-labels in model membranes. It is concluded that the longest values of T1 will generally be found at Q-band, noting that long values are advantageous for measurement of bimolecular collisions with oxygen. The contribution of dissolved molecular oxygen to the relaxation rate was found to be independent of microwave frequency up to 94 GHz for lipid-type spin-labels in membranes. This contribution is expressed in terms of the oxygen transport parameter W=T1-1 (Air)-T1-1 (N), which is a function of both concentration and translational diffusion of oxygen in the local environment of a spin-label. The new capabilities in measurement of the oxygen transport parameter using saturation-recovery (SR) EPR at Q- and W-band have been demonstrated in saturated (DMPC) and unsaturated (POPC) lipid bilayer membranes with the use of stearic acid ( n-SASL) and phosphatidylcholine ( n-PC) spin-labels, and compared with results obtained earlier at X-band. SR EPR spin-label oximetry at Q- and W-band has the potential to be a powerful tool for studying samples of small volume, ˜30 nL. These benefits, together with other factors such as a higher resonator efficiency parameter and a new technique for canceling free induction decay signals, are discussed.

  16. Pulse Oximetry Screening to Detect Cyanotic Congenital Heart Disease in Sick Neonates in a Neonatal Intensive Care Unit.

    PubMed

    Mathur, N B; Gupta, A; Kurien, S

    2015-09-01

    To evaluate pulse oximetry for detection of congenital cyanotic heart disease in sick neonates using echocardiography as gold standard. Pulse oximetry readings were taken at admission from 950 neonates from right upper limb and either foot with infant breathing room air. Pulse oximetry was considered abnormal if oxygen saturation at room air measured <90% or difference between right hand and foot was more than 3%. Persistent abnormality was considered positive result. Echocardiography was performed on all neonates with positive pulse oximetry (study group) and on one subsequent neonate with negative screen for each neonate with positive screen (controls). Pulse oximetry was positive in 210 neonates. It detected 20 out of 21 (95.2%) true positives. The sensitivity, specificity, positive predictive value, negative predictive value and odds ratio (95% CI) of pulse oximetry was 95.2%, 52.4%, 9.5, 99.5 and 22 (5.3, 91.4), respectively. Pulse oximetry screening is useful in detecting cyanotic heart diseases in sick newborns.

  17. Cost analysis of near-infrared spectroscopy tissue oximetry for monitoring autologous free tissue breast reconstruction.

    PubMed

    Pelletier, Aaron; Tseng, Charles; Agarwal, Shailesh; Park, Julie; Song, David

    2011-10-01

    Free flap monitoring typically requires specialized nursing that can increase medical costs. This study uses near-infrared spectroscopy (NIRS) tissue oximetry to monitor free tissue breast reconstruction. We hypothesize this practice will reduce medical costs by eliminating the need for specialized nursing. From August 2006 to January 2010, women undergoing unilateral free tissue breast reconstruction were enrolled and admitted postoperatively to either the surgical intensive care unit (ICU) or floor. Each underwent continuous monitoring using NIRS tissue oximetry and intermittent clinical examination with surface Doppler ultrasonography. Patient demographics, comorbidities, perioperative details, and financial data were recorded. There were 50 patients studied, all with abdominal-based flaps (25 per group). There were no statistically significant differences in patient demographics, comorbidities, mean flap weight, ischemia time, or length of stay between the ICU and floor groups. Four flaps had vascular complications, all detected by NIRS tissue oximetry. Comparison of hospital costs showed an average reduction of $1937 per patient when monitored on the surgical floor (P = 0.036). NIRS tissue oximetry is a sensitive and reliable monitoring tool, eliminating the need for specialized nursing care. The effect is decreased cost structure and increased hospital contribution margin for autologous free tissue breast reconstruction.

  18. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    ERIC Educational Resources Information Center

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-01-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

  19. Using of Local Information for Diagnosing Intranatal Adverse Conditions by Pulse Oximetry

    DTIC Science & Technology

    2007-11-02

    Fiedmann, J.W., Dudenhausen, �Continuous monitoring of fetal oxygen saturation by pulse oximetry�, Obstet Gynecol 1995;85:183-6. [6]. Dildy GA...Clark SL, Loucks CA. Intrapartum fetal pulse oximetry: Past, present, and future. Am J Obstet Gynecol 175:1-9, 1996. [7]. K. Fukunaga: Introduction

  20. Desaturation Patterns Detected by Oximetry in a Large Population of Athletes

    ERIC Educational Resources Information Center

    Garrido-Chamorro, Raul P.; Gonzalez-Lorenzo, Marta; Sirvent-Belando, Jose; Blasco-Lafarga, Cristina; Roche, Enrique

    2009-01-01

    Optimal exercise performance in well trained athletes can be affected by arterial oxygen saturation failure. Noninvasive detection of this phenomenon when performing a routine ergometric test can be a valuable tool for subsequent planning of the athlete's training, recovery, and nutrition. Oximetry has been used to this end. The authors studied…

  1. Desaturation Patterns Detected by Oximetry in a Large Population of Athletes

    ERIC Educational Resources Information Center

    Garrido-Chamorro, Raul P.; Gonzalez-Lorenzo, Marta; Sirvent-Belando, Jose; Blasco-Lafarga, Cristina; Roche, Enrique

    2009-01-01

    Optimal exercise performance in well trained athletes can be affected by arterial oxygen saturation failure. Noninvasive detection of this phenomenon when performing a routine ergometric test can be a valuable tool for subsequent planning of the athlete's training, recovery, and nutrition. Oximetry has been used to this end. The authors studied…

  2. Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

    ERIC Educational Resources Information Center

    Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

    2013-01-01

    We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

  3. The influence of red blood cell scattering in optical pathways of retinal vessel oximetry

    NASA Astrophysics Data System (ADS)

    LeBlanc, Serge Emile

    The ability to measure the oxygen saturation, oximetry, of retinal blood both non-invasively and in-vivo has been a goal of eye research for years. Retinal oximetry can in principle be achieved from the measurement of the reflectance spectrum of the ocular fundus. Oximetry calculations are however complicated by the scattering of red blood cells, the different pathways of light through blood and the ocular tissues that light interacts with before exiting the eye. The goal of this thesis was to investigate the influence of red blood cell scattering for different light paths relevant to retinal oximetry. Results of in-vitro whole blood experiments found calculated oxygen saturation differences between blood samples measured under different retinal light paths, and these differences did not depend on the absorbance path length. We also showed that the calculated oxygen saturation value determined by a multiple linear regression Beer-Lambert absorbance model depended on the wavelength range chosen for analysis. The wavelength dependency on the calculated oxygen saturation value is due in part to the correlation that exists between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficient spectra and to errors in the assumptions built into the Beer-Lambert absorbance model. A wavelength region with low correlation between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficients was found that is hypothesized to be a good range to calculate oxygen saturation using a multiple linear regression approach.

  4. Variation in high-frequency wave radiation from small repeating earthquakes as revealed by cross-spectral analysis

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Norishige; Uchida, Naoki; Matsuzawa, Toru; Okada, Tomomi; Nakajima, Junichi; Matsushima, Takeshi; Kono, Toshio; Hirahara, Satoshi; Nakayama, Takashi

    2016-11-01

    We examined the variation in the high-frequency wave radiation for three repeating earthquake sequences (M = 3.1-4.1) in the northeastern Japan subduction zone by waveform analyses. Earthquakes in each repeating sequence are located at almost the same place and show low-angle thrust type focal mechanisms, indicating that they represent repeated ruptures of a seismic patch on the plate boundary. We calculated cross-spectra of the waveforms and obtained the phases and coherences for pairs of events in the respective repeating sequences in order to investigate the waveform differences. We used waveform data sampled at 1 kHz that were obtained from temporary seismic observations we conducted immediately after the 2011 Tohoku earthquake near the source area. For two repeating sequences, we found that the interevent delay times for the two waveforms in a frequency band higher than the corner frequencies are different from those in a lower frequency band for particular event pairs. The phases and coherences show that there are coherent high-frequency waves for almost all the repeaters regardless of the high-frequency delays. These results indicate that high-frequency waves are always radiated from the same vicinity (subpatch) for these events but the time intervals between the ruptures of the subpatch and the centroid times can vary. We classified events in the sequence into two subgroups according to the high-frequency band interevent delays relative to the low-frequency band. For one sequence, we found that all the events that occurred just after (within 11 days) larger nearby earthquakes belong to one subgroup while other events belong to the other subgroup. This suggests that the high-frequency wave differences were caused by stress perturbations due to the nearby earthquakes. In summary, our observations suggest that high-frequency waves from the repeating sequence are radiated not from everywhere but from a long-duration subpatch within the seismic slip area. The

  5. Temporal variation characteristics of shear-wave splitting for the Rushan earthquake swarm of Shandong Province

    NASA Astrophysics Data System (ADS)

    Miao, Qingjie; Liu, Xiqiang

    2017-03-01

    The seismicity in Rushan region of Shandong Province is characterized by small swarms after the ML3.8 Rushan earthquake on October 1, 2013, and this situation continues up to now. Four earthquakes with ML4.7, ML4.5, ML4.1 and ML5.0 occurred from January of 2014 to May of 2015 cause great social effects. Based on the seismic records from the Rushan station, this paper calculated the shear-wave splitting parameters of 224 small earthquakes of Rushan earthquake swarm. The result shows that the polarization direction of the fast shear-wave is consistent with the principal compressive stress direction of the Shandong peninsula; on the other hand, the time delay has obvious change before and after the four earthquakes, that is, it raised about one month and declined about twelve days before earthquake. All the characteristics can be taken as the precursor indicator for earthquake prediction based on stress.

  6. Satellite altimetry reveals spatial patterns of variations in the Baltic Sea wave climate

    NASA Astrophysics Data System (ADS)

    Kudryavtseva, Nadezhda; Soomere, Tarmo

    2017-08-01

    The main properties of the climate of waves in the seasonally ice-covered Baltic Sea and its decadal changes since 1990 are estimated from satellite altimetry data. The data set of significant wave heights (SWHs) from all existing nine satellites, cleaned and cross-validated against in situ measurements, shows overall a very consistent picture. A comparison with visual observations shows a good correspondence with correlation coefficients of 0.6-0.8. The annual mean SWH reveals a tentative increase of 0.005 m yr-1, but higher quantiles behave in a cyclic manner with a timescale of 10-15 years. Changes in the basin-wide average SWH have a strong meridional pattern: an increase in the central and western parts of the sea and a decrease in the east. This pattern is likely caused by a rotation of wind directions rather than by an increase in the wind speed.

  7. Retinal oximetry measures systemic hypoxia in central nervous system vessels in chronic obstructive pulmonary disease

    PubMed Central

    Bragason, David; Hardarson, Sveinn Hakon; Vacchiano, Charles; Gislason, Thorarinn; Kristjansdottir, Jona Valgerdur; Kristjansdottir, Gudrun; Stefánsson, Einar

    2017-01-01

    Background Determination of the blood oxyhemoglobin saturation in the retinal vessels of the eye can be achieved through spectrophotometric retinal oximetry which provides access to the state of oxyhemoglobin saturation in the central nervous system circulation. The purpose of this study was to test the capability of the Oxymap T1 oximeter to detect systemic hypoxemia and the effect of supplemental oxygen on retinal vessel oxyhemoglobin saturation. Methods Oxygen saturation of hemoglobin in retinal arterioles and venules was measured in 11 subjects with severe chronic obstructive pulmonary disease (COPD) on long term oxygen therapy. Measurements were made with and without their daily supplemental oxygen. Eleven healthy age and gender matched subjects were measured during ambient air breathing for comparison of oxyhemoglobin saturation in retinal arterioles and venules. Retinal arteriolar oxyhemoglobin saturation in COPD subjects inspiring ambient air was compared with finger pulse oximetry and blood samples from radial artery. Results COPD subjects had significantly lower oxyhemoglobin saturation during ambient air breathing than healthy controls in both retinal arterioles (87.2%±4.9% vs. 93.4%±4.3%, p = 0.02; n = 11) and venules (45.0%±10.3% vs. 55.2%±5.5%, p = 0.01). Administration of their prescribed supplemental oxygen increased oxyhemoglobin saturation in retinal arterioles (87.2%±4.9% to 89.5%±6.0%, p = 0.02) but not in venules (45.0%±10.3% to 46.7%±12.8%, p = 0.3). Retinal oximetry values were slightly lower than radial artery blood values (mean percentage points difference = -5.0±5.4, 95% CI: -15.68 to 5.67) and finger pulse oximetry values (-3.1±5.5, 95% CI: -14.05 to 7.84). Conclusions The noninvasive Oxymap T1 retinal oximetry detects hypoxemia in central nervous system vessels in patients with severe COPD compared with healthy controls. The instrument is sensitive to changes in oxygen breathing but displays slightly lower measures than finger

  8. Retinal oximetry measures systemic hypoxia in central nervous system vessels in chronic obstructive pulmonary disease.

    PubMed

    Eliasdottir, Thorunn Scheving; Bragason, David; Hardarson, Sveinn Hakon; Vacchiano, Charles; Gislason, Thorarinn; Kristjansdottir, Jona Valgerdur; Kristjansdottir, Gudrun; Stefánsson, Einar

    2017-01-01

    Determination of the blood oxyhemoglobin saturation in the retinal vessels of the eye can be achieved through spectrophotometric retinal oximetry which provides access to the state of oxyhemoglobin saturation in the central nervous system circulation. The purpose of this study was to test the capability of the Oxymap T1 oximeter to detect systemic hypoxemia and the effect of supplemental oxygen on retinal vessel oxyhemoglobin saturation. Oxygen saturation of hemoglobin in retinal arterioles and venules was measured in 11 subjects with severe chronic obstructive pulmonary disease (COPD) on long term oxygen therapy. Measurements were made with and without their daily supplemental oxygen. Eleven healthy age and gender matched subjects were measured during ambient air breathing for comparison of oxyhemoglobin saturation in retinal arterioles and venules. Retinal arteriolar oxyhemoglobin saturation in COPD subjects inspiring ambient air was compared with finger pulse oximetry and blood samples from radial artery. COPD subjects had significantly lower oxyhemoglobin saturation during ambient air breathing than healthy controls in both retinal arterioles (87.2%±4.9% vs. 93.4%±4.3%, p = 0.02; n = 11) and venules (45.0%±10.3% vs. 55.2%±5.5%, p = 0.01). Administration of their prescribed supplemental oxygen increased oxyhemoglobin saturation in retinal arterioles (87.2%±4.9% to 89.5%±6.0%, p = 0.02) but not in venules (45.0%±10.3% to 46.7%±12.8%, p = 0.3). Retinal oximetry values were slightly lower than radial artery blood values (mean percentage points difference = -5.0±5.4, 95% CI: -15.68 to 5.67) and finger pulse oximetry values (-3.1±5.5, 95% CI: -14.05 to 7.84). The noninvasive Oxymap T1 retinal oximetry detects hypoxemia in central nervous system vessels in patients with severe COPD compared with healthy controls. The instrument is sensitive to changes in oxygen breathing but displays slightly lower measures than finger pulse oximetry or radial artery

  9. Temperature variation induced by the pulsed-periodic laser pumping under terahertz wave generation

    NASA Astrophysics Data System (ADS)

    Kitaeva, G. Kh; Moiseenko, E. V.; Shepelev, A. V.

    2017-09-01

    During nonlinear-optical parametric frequency conversion the heat-related effects occur, considerably influencing the conversion process. We develop versatile methods for analytic and numerical calculations of thermo-optical parameters and the temperature distribution inside a non-linear crystal pumped by periodic laser pulses. As an example, numerical results are presented for a number of laser-based schemes actual for the non-linear optical terahertz wave generation and parametric frequency conversion processes.

  10. Adjoint-Free Variational Data Assimilation into a Regional Wave Model

    DTIC Science & Technology

    2015-07-01

    sector, and SWH from satellite altimeter along a geographic track. Numerical experiments demonstrate computational feasibility and robustness of the...noticeable effect when assimilated in combination with other types of data. In particular, when spectral data from a single mooring are used, the satellite ...the advent of massive obser- vations of sea surface roughness from satellites , the forecast skill of the wave models (WMs) acquired new prospects for

  11. A methodology for structural health monitoring with diffuse ultrasonic waves in the presence of temperature variations.

    PubMed

    Lu, Yinghui; Michaels, Jennifer E

    2005-10-01

    Diffuse ultrasonic waves for structural health monitoring offer the advantages of simplicity of signal generation and reception, sensitivity to damage, and large area coverage; however, there are the serious disadvantages of no accepted methodology for analyzing the complex recorded signals and sensitivity to environmental changes such as temperature and surface conditions. Presented here is a methodology for applying diffuse ultrasonic waves to the problem of detecting structural damage in the presence of unmeasured temperature changes. This methodology is based upon the prediction and observation that the first order effect of a temperature change on a diffuse ultrasonic wave is a time dilation or compression. A multi-step procedure is implemented to (1) record a set of baseline waveforms from the undamaged specimen at temperatures spanning the expected operating range, (2) select a waveform from the baseline set whose temperature is the closest to that of a subsequently measured signal, (3) adjust this baseline waveform to best match the signal, and (4) calculate an error parameter between the signal and the adjusted waveform and compare this parameter to a threshold to determine the structural status. This procedure is applied to experimental data from aluminum plate specimens with artificial flaws. Probability of detection and the minimum flaw size detected are presented as a function of the size of the baseline waveform set. It is shown that a probability of detection of over 95% can be achieved with a small number of baseline waveforms.

  12. Modeling Mars Cyclogenesis and Frontal Waves: Seasonal Variations and Implications on Dust Activity

    NASA Technical Reports Server (NTRS)

    Hollingsworth, J. L.; Kahre, M. A.

    2014-01-01

    Between late autumn through early spring,middle and high latitudes onMars exhibit strong equator-to-polemean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic period waves) [1, 2]. For a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, these large-scale, extratropical weather disturbances are critical components of the global circulation. The wave-like disturbances serve as agents in the transport of heat and momentum between low and high latitudes of the planet. Through cyclonic/anticyclonic winds, intense shear deformations, contractions-dilatations in temperature and density, and sharp perturbations amongst atmospheric tracers (i.e., dust, volatiles (e.g., water vapor) and condensates (e.g., water-ice cloud particles)), Mars' extratropical weather systems have significant sub-synoptic scale ramifications by supporting atmospheric frontal waves (Fig. 1).

  13. Variation of shear and compressional wave modulus upon saturation for pure pre-compacted sands

    NASA Astrophysics Data System (ADS)

    Bhuiyan, M. H.; Holt, R. M.

    2016-07-01

    Gassmann's fluid substitution theory is commonly used to predict seismic velocity change upon change in saturation, and is hence essential for 4-D seismic and AVO studies. This paper addresses the basics assumptions of the Gassmann theory, in order to see how well they are fulfilled in controlled laboratory experiments. Our focus is to investigate the sensitivity of shear modulus to fluid saturation, and the predictability of Gassmann's fluid substitution theory for P-wave modulus. Ultrasonic P- and S-wave velocities in dry and saturated (3.5 wt per cent NaCl) unconsolidated clean sands (Ottawa and Columbia) were measured in an oedometer test system (uniaxial strain conditions) over a range of 0.5-10 MPa external vertical stress. This study shows shear modulus hardening upon brine saturation, which is consistent with previous data found in the literature. Analysis of the data shows that most of the hardening of the ultrasonic shear modulus may be explained by Biot dispersion. Isotropic Gassmann's fluid substitution is found to underestimate the P-wave modulus upon fluid saturation. However, adding the Biot dispersion effect improves the prediction. More work is required to obtain good measurements of parameters influencing dispersion, such as tortuosity, which is very ambiguous and challenging to measure accurately.

  14. Monitoring the bovine fetus during stage II of parturition using pulse oximetry.

    PubMed

    Bleul, U; Kähn, W

    2008-02-01

    Measurement of oxygen saturation using pulse oximetry is an established method of continuous monitoring of the well-being of the human fetus during parturition. In veterinary medicine, pulse oximetry has been used almost exclusively in intensive care and anesthesiology. The goal of the present study was to investigate the physiological changes in oxygen saturation of the bovine fetus during stage II of parturition and to determine whether the findings can be used to predict postnatal acidosis. The correlation between the oxygen saturation (SpO(2)) measured via pulse oximetry and the oxygen saturation (SaO(2)) of arterial blood measured via blood gas analysis was determined in 23 newborn calves. In addition, the oxygen saturation was monitored continuously via pulse oximetry (FSpO(2)) in 33 bovine fetuses during stage II of parturition. Correlations between the FSpO(2) values during the last 30 and 5min of stage II of parturition and the postpartum values for pH, partial pressures of oxygen and carbon dioxide, bicarbonate concentration, BE, SaO(2) and lactate concentration in arterial blood were determined. There was a high correlation between SpO(2) and SaO(2) postpartum (r=0.923). The FSpO(2) values correlated moderately with the pH and BE and weakly with the lactate concentration postpartum; calves with a pH<7.2, a BE<-3mM/L or a lactate concentration of >5.4mM/L had significantly lower FSpO(2) values than non-acidotic calves. FSpO(2) values <30% for a period of at least 2min had the highest predictive value for a calf born with a pH<7.2. Pulse oximetry is a novel method of monitoring the bovine fetus during parturition; however, technical modifications are required to improve its usefulness.

  15. Evaluation of Pulse Oximetry in the Early Detection of Cyanotic Congenital Heart Disease in Newborns

    PubMed Central

    Movahedian, Amir Hosein; Mosayebi, Ziba; Sagheb, Setareh

    2016-01-01

    Background: Delayed or missed diagnosis of critical and cyanotic congenital heart disease (CHD) in asymptomatic newborns may result in significant morbidity and mortality. The aim of this study was to determine the accuracy of pulse oximetry screening performed on the first day of life for the early detection of critical and cyanotic CHD in apparently normal newborns. Methods: This cross-sectional study used postductal pulse oximetry to evaluate term neonates born between 2008 and 2011 with normal physical examinations. Functional oxygen saturation < 95% was considered abnormal, and second measurement was done 2 hours later. If the second measurement remained < 95%, an echocardiogram was performed. On enrolment in the study, the following data for each neonate were recorded: gestational age, gender, birth weight, mode of delivery, and mother’s age. Results: During the study period, totally 3,846 newborns were evaluated. Of the whole study population, 304 (7.9%) babies had a postductal functional saturation < 95%. The second measurement was also < 95% in 104 (2.7%) neonates. The mean age of the neonates at the time of pulse oximetry was 18.91 ± 8.61 (min = 4.5 and max = 49) hours. Forty-nine percent of the subjects were female and 51% were male. Echocardiography was performed on 81 out of 104 newborns, and 14 (0.36%) of them had CHD. The types of CHD in our patients were tetralogy of Fallot (3 cases), transposition of the great vessels (2 cases), double-outlet right ventricle (2 cases), truncus arteriosus, total anomalous pulmonary venous return, atrioventricular septal defect, pulmonary atresia, persistent pulmonary hypertension, ventricular septal defect, and atrial septal defect (1 case for each type). The best time for pulse oximetry was within 8-24 hours of the newborns’ life. Conclusion: Pulse oximetry screening along with clinical examination may be able to assist in the early detection of critical and cyanotic CHD in asymptomatic newborns. PMID:27928258

  16. The Use of Pulse Oximetry to Determine Hypoxemia in Acute Exacerbations of COPD.

    PubMed

    Garcia-Gutierrez, Susana; Unzurrunzaga, Anette; Arostegui, Inmaculada; Quintana, Jose María; Pulido, Esther; Gallardo, Maria Soledad; Esteban, Cristóbal

    2015-01-01

    There is little evidence that the guideline-recommended oxygen saturation of 92% is the best cut-off point for detecting hypoxemia in COPD exacerbations. To detect and validate pulse oximetry oxygen saturation cut-off values likely to detect hypoxemia in patients with aeCOPD, to explore the correlation between oxygen saturation measured by pulse oximetry and hypoxemia or hypercapnic respiratory failure. Cross-sectional study nested in the IRYSS-COPD study with 2,181 episodes of aeCOPD recruited between 2008 and 2010 in 16 hospitals belonging to the Spanish Public Health System. Data collected include determination of oxygen saturation by pulse oximetry upon arrival in the emergency department (ED), first arterial blood gasometry values, sociodemographic information, background medical history and clinical variables upon ED arrival. Logistic regression models were performed using as the dependent variables hypoxemia (PaO2 < 60 mmHg) and hypercapnic respiratory failure (PaO2 < 60 mmHg and PaCO2 > 45). Optimal cut-off points were calculated. The correlation coefficient between oxygen saturation and pO2 measured by arterial blood gasometry was 0.89. The area under the curve (AUC) for the hypoxemia model was 0.97 (0.96-0.98) and the optimal cut-off point for hypoxemia was an oxygen saturation of 90%. The AUC for hypercapnic respiratory failure was 0.90 (0.87-0.92) and the optimal cut-off point was an oxygen saturation of 88%. Our results support current recommendations for ordering blood gasometry based on pulse oximetry oxygen saturation cut-offs for hypoxemia. We also provide easy to use formulae to calculate pO2 from oxygen saturation measured by pulse oximetry.

  17. Development and clinical evaluation of a new sensor design for buccal pulse oximetry in horses.

    PubMed

    Reiners, J K; Rossdeutscher, W; Hopster, K; Kästner, S B R

    2017-08-18

    The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes. The objectives of this study were 1) to develop an improved sensor design for horses to be used at an appropriate anatomical site and 2) to evaluate this design in an experimental study. In vivo experiment. A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed and used with the Nonin 2500A Vet pulse oximetry monitor. Thirteen anaesthetised warmblood horses were included into a desaturation protocol (100 - 70% SaO2 ). SpO2 and pulse frequency values were recorded, using SaO2 calculated from blood gas analysis and invasive pulse frequency measurements as reference methods. Bias and precision were evaluated by calculations of the root mean square deviation (Arms ). The agreement of the methods was tested with Bland-Altman analysis. The quality of the pulse frequency readings determined the quality of the SpO2 -readings. Good pulse signal strength resulted in a SpO2 -accuracy comparable to that of the original sensor (Nonin 2000SL: Arms = 3%; N1: Arms = 3.60%; N2b: Arms = 3.46%). Especially at heart rates ≤30 bpm, pulse rate readings that were about twice as high as the reference value occurred. Their exclusion from the dataset resulted in a pulse rate accuracy similar to that of the original sensor. Bland-Altman plots showed limits of agreement typical of pulse oximeters. The pulse frequency accuracy requires further improvement. The usability in clinical cases needs to be tested. The new sensor design has been shown to be suitable for buccal pulse oximetry in horses. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  18. Long Range Kelvin Wave Propagation of Transport Variations in the Pacific Ocean Equatorial Currents: Part II

    NASA Astrophysics Data System (ADS)

    Halpern, D.; Fukumori, I.; Menemenlis, D.; Wang, X.

    2013-12-01

    In Part I, Knox and Halpern (Journal of Marine Research, 40 Supplement, 329-339, 1982) vertically integrated zonal current observations recorded in March-May 1980 at seven depths from the thermocline to 15 m at the equator and 75 km north and south of the equator near 152°W and also simultaneously at three similar sites at 110°W. Their in-situ current measurements provided the first persuasive evidence of Kelvin wave motion propagating within the Equatorial Undercurrent (EUC). A 7-day decrease in transport at peak amplitude of the Kelvin wave pulse at 152°W and 110°W has remained a curiosity with regards to its repeatability at other times within the year and in other years. The advent of realistic currents generated with an ocean general circulation model constrained by observations (excluding current measurements) provided an opportunity to re-explore Kelvin wave motion in the Pacific EUC. We use the Estimating the Circulation and Climate of the Ocean (ECCO) - Ice interactions in Earth System (IcES) solutions or ocean state estimates, which represent complete, consistent, and optimal statistical estimates of the global ocean state. ECCO-IcES solutions exist for 2004 and four other years. Twelve 10-m thick layers cover the top 120 m with nine additional layers in the uppermost 400 m. The horizontal grid spacing is 19 km and 3-day averaged quantities are archived. Three longitudes (170°W, 140°W, 110°W) were initially chosen to examine Kelvin wave characteristics; additional longitudes will be described. The large burst in ECCO-IcES EUC transport (defined as eastward flow between the surface and 400 m and from 1.5°S to 1.5°N) in April-May 2004 replicated the well-known annual surfacing of the EUC. The large bursts of EUC transport at 140°W in late January, late April, middle July, and early September and a more modest burst in early November compared exceedingly well with similar bursts at 170°W and 110°W. The average magnitude at 140°W was 50 Sv. Each

  19. Imaging textural variation in the acoustoelastic coefficient of aluminum using surface acoustic waves.

    PubMed

    Ellwood, R; Stratoudaki, T; Sharples, S D; Clark, M; Somekh, M G

    2015-11-01

    Much interest has arisen in nonlinear acoustic techniques because of their reported sensitivity to variations in residual stress, fatigue life, and creep damage when compared to traditional linear ultrasonic techniques. However, there is also evidence that the nonlinear acoustic properties are also sensitive to material microstructure. As many industrially relevant materials have a polycrystalline structure, this could potentially complicate the monitoring of material processes when using nonlinear acoustics. Variations in the nonlinear acoustoelastic coefficient on the same length scale as the microstructure of a polycrystalline sample of aluminum are investigated in this paper. This is achieved by the development of a measurement protocol that allows imaging of the acoustoelastic response of a material across a samples surface at the same time as imaging the microstructure. The development, validation, and limitations of this technique are discussed. The nonlinear acoustic response is found to vary spatially by a large factor (>20) between different grains. A relationship is observed when the spatial variation of the acoustoelastic coefficient is compared to the variation in material microstructure.

  20. Small-scale longitudinal variations in the daytime equatorial thermospheric wave dynamics as inferred from oxygen dayglow emissions

    NASA Astrophysics Data System (ADS)

    Karan, Deepak K.; Pallamraju, Duggirala

    2017-06-01

    The equatorial upper atmospheric dynamic processes show both latitudinal and longitudinal variabilities. While the variability in latitudes can exist over small distances (approximately hundreds of kilometers), the longitudinal behavior has been shown to be existing mainly over large spatial separations (approximately thousands of kilometers). In the present work we have used variations in thermospheric optical dayglow emissions at OI 557.7, 630.0, and 777.4 nm, as tracers of neutral dynamics. These emissions are obtained simultaneously from a high-resolution slit spectrograph, Multi wavelength Imaging Spectrograph using Echelle grating, from a low-latitude location, Hyderabad (17.5°N, 78.4°E; 8.9°N magnetic latitude) in India, to investigate the longitudinal differences in the upper atmospheric processes over short separations. Spectral analyses of gravity waves carried out on the dayglow emission intensity variations for different independent viewing directions on some days show dissimilar periodicities suggesting the existence of longitudinal differences. Gravity wave scale sizes and the propagation characteristics on these days are different from those in which longitudinal differences are not seen. Further, the zenith diurnal emission intensity patterns are different on the days with and without the observed longitudinal variability. This work shows for the first time that longitudinal differences in upper atmospheric processes can exist at even as small as 3° longitude separations. Such longitudinal differences seen in the neutral dayglow emission intensities are attributed to the zonal variation in the daytime equatorial electrodynamics.Plain Language SummaryThe longitudinal variability in the upper atmospheric phenomena has been reported over large distances in the literature that span greater than several thousands of kilometer. However, nothing is known as to what happens on the smaller distances. Using</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004QJRMS.130.2991G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004QJRMS.130.2991G"><span>Boundary-layer <span class="hlt">variations</span> due to orographic-<span class="hlt">wave</span> breaking in the presence of rotation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grisogono, B.; Enger, L.</p> <p>2004-10-01</p> <p>A mesoscale numerical model is used to study the atmospheric boundary-layer (ABL) response to nonlinear orographic forcing with Coriolis effect, f, over a mountain with length (the cross-wind component) comparable to the Rossby radius of deformation, LR. The orographic-<span class="hlt">wave</span> breaking occurring for Froude number Fr < 1, affected by f > 0, intensifies on the northern flank for westerly flows, as also found in other recent studies. A cumulative effect occurs as the Coriolis force lifts the northern ABL top and generates a stronger low-level jet (LLJ) than on the southern side. A differential layering also appears, since the specific humidity is higher in the lower southern ABL than in the related northern ABL, and vice versa. By contrast, there are higher values of the turbulent kinetic energy and humidity in the upper northern ABL. The breaking of flow symmetry around the orography due to f changes both the vertical vorticity and horizontal divergence field, (, D), it modulates eddies and turbulence leading to the differential layering of the ABL. The stronger northern LLJ and its weaker southern counterpart, both meandering, together with the asymmetric <span class="hlt">wave</span> breaking, induce strong lee-side fluctuations of the (<IMG SRC="/iso-ents/isogrk32/zeta-s.gif" ALT="zeta">, D) field in the presence of f. The enhanced (<IMG SRC="/iso-ents/isogrk32/zeta-s.gif" ALT="zeta">, D) production due to <span class="hlt">wave</span> breaking over the distance <IMG SRC="/iso-ents/isotech/ap.gif" ALT="ap">LR, the primary atmosphere-orography resonance occurs mainly in the vertical, while the 'f-enhancement' occurs in the horizontal plane. In this way, the initial mesoscale forcing may extend its effects over the synoptic scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22518969','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22518969"><span>LONG-TERM <span class="hlt">VARIATION</span> IN THE SUN’S ACTIVITY CAUSED BY MAGNETIC ROSSBY <span class="hlt">WAVES</span> IN THE TACHOCLINE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zaqarashvili, Teimuraz V.; Oliver, Ramon; Ballester, Jose Luis; Hanslmeier, Arnold; Carbonell, Marc; Gachechiladze, Tamar; Usoskin, Ilya G.</p> <p>2015-06-01</p> <p>Long-term records of sunspot number and concentrations of cosmogenic radionuclides (10Be and 14C) on the Earth reveal the <span class="hlt">variation</span> of the Sun's magnetic activity over hundreds and thousands of years. We identify several clear periods in sunspot, 10Be, and 14C data as 1000, 500, 350, 200, and 100 years. We found that the periods of the first five spherical harmonics of the slow magnetic Rossby mode in the presence of a steady toroidal magnetic field of 1200–1300 G in the lower tachocline are in perfect agreement with the timescales of observed <span class="hlt">variations</span>. The steady toroidal magnetic field can be generated in the lower tachocline either due to the steady dynamo magnetic field for low magnetic diffusivity or due to the action of the latitudinal differential rotation on the weak poloidal primordial magnetic field, which penetrates from the radiative interior. The slow magnetic Rossby <span class="hlt">waves</span> lead to <span class="hlt">variations</span> of the steady toroidal magnetic field in the lower tachocline, which modulate the dynamo magnetic field and consequently the solar cycle strength. This result constitutes a key point for long-term prediction of the cycle strength. According to our model, the next deep minimum in solar activity is expected during the first half of this century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22483224','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22483224"><span>Mass <span class="hlt">variation</span> of a thin liquid film driven by an acoustic <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Batson, W.; Agnon, Y.; Oron, A.</p> <p>2015-06-15</p> <p>In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the “one-sided” model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable <span class="hlt">wave</span> numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling <span class="hlt">waves</span> encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhFl...27f2106B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhFl...27f2106B"><span>Mass <span class="hlt">variation</span> of a thin liquid film driven by an acoustic <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Batson, W.; Agnon, Y.; Oron, A.</p> <p>2015-06-01</p> <p>In this work, we investigate the dynamics of a thin liquid film subjected to an acoustic field in its bounding vapor space. For large acoustic wavelengths, the field imposes a spatially uniform, temporally periodic temperature and pressure at the vapor side of the film interface, which leads to a periodic driving force for mass exchange with the vapor. Neglecting the dynamics of the vapor space, we adopt the "one-sided" model for evaporation/condensation of thin liquid films. In the interest of determining the effect of oscillatory mass exchange on film stability, we consider films in thermodynamic equilibrium with the mean vapor conditions. The effects of oscillatory phase change on both linear stability and nonlinear dynamics are investigated for slightly inclined ceiling films that are destabilized by gravity and subject to thermocapillary effects. At linear order, this mass exchange is not found to alter the band of unstable <span class="hlt">wave</span> numbers and only marginally affects the growth rates. Additionally, the mass exchanged during evaporation is balanced by condensation so that the total mass of the liquid film is conserved. However, due to nonlinear effects, we find that traveling <span class="hlt">waves</span> encouraged by the inclination are subject to net mass loss. It is then found that normal thermocapillary effects enhance this loss, and that anomalous thermocapillarity mitigates or even reverses the loss to a mass gain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070005090','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070005090"><span>Modeling the Observed Solar Cycle <span class="hlt">Variations</span> of the Quasi-biennial Oscillation (QBO): Amplification by <span class="hlt">Wave</span> Forcing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, Hans G.; Mengel, John G.; Huang, Frank T.; Chan, Kwing L.</p> <p>2007-01-01</p> <p>In several papers, the solar cycle (SC) effect in the lower atmosphere has been linked observationally to the Quasi-biennial Oscillation (QBO) of the zonal circulation, which is generated primarily by small-scale gravity <span class="hlt">waves</span> (GW). Salby and Callaghan (2000) in particular analyzed the QBO, covering more than 40 years, and discovered that it contains a large SC signature at 20 km. With our Numerical Spectral Model (NSM), we conducted a 3D study to describe the QBO under the influence of the SC, and some results have been published (Mayr et al., GRL, 2005,2006). For a SC period of 10 years, the relative amplitude of radiative forcing is taken to vary exponentially with height, i.e., 0.2% at the surface, 2% at 50 km, 20% at 100 km and above. Applying spectral analysis to filter out and identify the SC signature, the model generates a relatively large modulation of the QBO, which reproduces the observations qualitatively. Our numerical results demonstrate that the modulation of the QBO, with constant phase relative to the SC, persist at least for 60 years. The same model run generates in the seasonal <span class="hlt">variations</span> a hemispherically symmetric Equatorial Annual Oscillation (EAO, with 12-month period), which is confined to low latitudes like the QBO and is also modulated by the SC. Although the amplitude of the EAO is relatively small, its SC modulation is large, and it is in phase with that of the QBO. The SC modulated EAO is evidently the pathway and pacemaker for the solar influence on the QBO. To shed light on the dynamical processes involved, we present model results that show how the seasonal cycle induces the SC modulations of the EAO and QBO. Our analysis further demonstrates that the SC modulations of the QBO and EAO are amplified by the GW interaction with the flow. The GW momentum source clearly shows a SC modulation that is in phase with the corresponding modulations of the QBO and EAO. By tapping the momentum from the upward propagating GWs, the QBO and EAO</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT........22Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT........22Y"><span>Diffuse Optical Imaging and Spectroscopy of the Human Breast for Quantitative <span class="hlt">Oximetry</span> with Depth Resolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Yang</p> <p></p> <p>Near-infrared spectral imaging for breast cancer diagnostics and monitoring has been a hot research topic for the past decade. Here we present instrumentation for diffuse optical imaging of breast tissue with tandem scan of a single source-detector pair with broadband light in transmission geometry for tissue <span class="hlt">oximetry</span>. The efforts to develop the continuous-<span class="hlt">wave</span> (CW) domain instrument have been described, and a frequency-domain (FD) system is also used to measure the bulk tissue optical properties and the breast thickness distribution. We also describe the efforts to improve the data processing codes in the 2D spatial domain for better noise suppression, contrast enhancement, and spectral analysis. We developed a paired-wavelength approach, which is based on finding pairs of wavelength that feature the same optical contrast, to quantify the tissue oxygenation for the absorption structures detected in the 2D structural image. A total of eighteen subjects, two of whom were bearing breast cancer on their right breasts, were measured with this hybrid CW/FD instrument and processed with the improved algorithms. We obtained an average tissue oxygenation value of 87% +/- 6% from the healthy breasts, significantly higher than that measured in the diseased breasts (69% +/- 14%) (p < 0.01). For the two diseased breasts, the tumor areas bear hypoxia signatures versus the remainder of the breast, with oxygenation values of 49 +/- 11% (diseased region) vs. 61 +/- 16% (healthy regions) for the breast with invasive ductal carcinoma, and 58 +/- 8% (diseased region) vs 77 +/- 11% (healthy regions) for ductal carcinoma in situ. Our subjects came from various ethnical/racial backgrounds, and two-thirds of our subjects were less than thirty years old, indicating a potential to apply the optical mammography to a broad population. The second part of this thesis covers the topic of depth discrimination, which is lacking with our single source-detector scan system. Based on an off</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMDI51B2136M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMDI51B2136M"><span>Earth's core: Temporal <span class="hlt">variations</span> using body <span class="hlt">waves</span>, and implications for fast differential rotation of the inner core</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mäkinen, A. M.; Deuss, A. F.</p> <p>2011-12-01</p> <p>Differential rotation of the Earth's inner core has proved to be a seismological enigma over the past fifteen years. Originally predicted in some geodynamo models, body-<span class="hlt">wave</span> studies have resolved rates of up to 1°/year for this differential rotation. Most previous body-<span class="hlt">wave</span> studies have focussed on events in the South Sandwich Islands, recorded at station COL in Alaska. Here we expand on previous geometries to achieve a more global coverage of the inner core, using PKPbc-PKPdf travel time residuals to shed light on temporal <span class="hlt">variations</span> in the core over some 25 years. We test for differential rotation of the inner core by seeking displacement of inner-core heterogeneities over time. In order to remove the effect of ray path dependent spatial <span class="hlt">variations</span> on time <span class="hlt">variations</span>, we introduce a new method of space-flattening, applied either in longitude or latitude. This allows for the use of polar, semi-equatorial and equatorial ray geometries. We start by re-analysing polar paths from South Sandwich Island to stations COL and INK in North America, finding that travel time residuals are varying on a 25-year time scale. These results could indicate a possible differential rotation of the inner core in an eastward sense, at a rate of 0.12-0.38°/year. This is in agreement with previous studies. However, station DAWY - to which inner-core ray paths resemble those to COL - yields, at best, a westward rotation of the inner core, incompatible with the COL/INK inferred rotation. We then employ earthquakes in the Aleutian Islands region, observed at BOSA and LBTB in southern Africa. These too exhibit temporal <span class="hlt">variations</span> in the core-sensitive residuals, but these <span class="hlt">variations</span> are not reconcilable with the South Sandwich Islands-COL/INK results regarding rotation. Our final piece of evidence for both the presence of temporal <span class="hlt">variations</span> in core-sensitive ray paths and the incompatibility of these <span class="hlt">variations</span> with a fast differential rigid-body rotation of the inner core comes from use</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSA21A0268Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSA21A0268Y"><span>Seasonal <span class="hlt">variations</span> of stratospheric gravity <span class="hlt">waves</span> in Antarctica and correlations to polar mesospheric cloud brightness in summer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamashita, C.; Chu, X.; Huang, W.; Nott, G. J.; Espy, P. J.</p> <p>2007-12-01</p> <p>Gravity <span class="hlt">waves</span> (GWs) play an important role in the dynamics of global middle and upper atmosphere. However, quantitative characterization of GWs in the upper stratosphere is still rare in Antarctica. Here we present a study of stratospheric GW parameters and seasonal <span class="hlt">variations</span> using the data obtained with the University of Illinois Fe Boltzmann/Rayleigh lidar at the South Pole (90°S) from December 1999 to January 2001 and at Rothera (67.5°S, 68.0°W) from December 2002 to March 2005. Through analyzing the Rayleigh lidar density data in 30-60 km, GW parameters are derived for the South Pole and Rothera, and the results are comparable. The annual mean GW vertical wavelength is 4.3 +/- 1.5 km, vertical phase speed is 0.33 +/- 0.15 m/s, and the period is 245 +/- 110 min. We characterize the stratospheric GW strength with the root- mean-square (RMS) relative density perturbation. The seasonal <span class="hlt">variation</span> of GW strength is clear at Rothera, with the maximum in winter and the minimum in summer. No significant seasonal <span class="hlt">variations</span> are observed at the South Pole. The data also show that the GW period is shorter in summer than in winter at Rothera. In addition, the stratospheric GW strength is negatively correlated with PMC brightness at Rothera but no significant correlation at the South Pole. Two important factors, i.e., the wind filtering effect and topographical GW source difference, are investigated in order to explain the GW seasonal <span class="hlt">variations</span>. We then apply a GW ray-tracing model to analyze the GW source and propagation. The correlation between GW strength and PMC brightness also provides a clue of GW propagation from the stratosphere to the mesosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15852924','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15852924"><span>[<span class="hlt">Wave</span>-type time series <span class="hlt">variation</span> of the correlation between NDVI and climatic factors].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bi, Xiaoli; Wang, Hui; Ge, Jianping</p> <p>2005-02-01</p> <p>Based on the 1992-1996 data of 1 km monthly NDVI and those of the monthly precipitation and mean temperature collected by 400 standard meteorological stations in China, this paper analyzed the temporal and spatial dynamic changes of the correlation between NDVI and climatic factors in different climate districts of this country. The results showed that there was a significant correlation between monthly precipitations and NDVI. The <span class="hlt">wave</span>-type time series model could simulate well the temporal dynamic changes of the correlation between NDVI and climatic factors, and the simulated results of the correlation between NDVI and precipitation was better than that between NDVI and temperature. The correlation coefficients (R2) were 0.91 and 0.86, respectively for the whole country.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJNAO...7..364K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJNAO...7..364K"><span>Study on <span class="hlt">variation</span> in ship's forward speed under regular <span class="hlt">waves</span> depending on rudder controller</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Sung-Soo; Kim, Soon-Dong; Kang, Donghoon; Lee, JongHyun; Lee, Seung Jae; Jung, Kwang Hyo</p> <p>2015-06-01</p> <p>The purpose of this research is to compare and analyze the advanced speed of ships with different rudder controller in wavy condition by using a simulation. The commercial simulation tool named AQWA is used to develop the simulation of ship which has 3 degree of freedom. The nonlinear hydrodynamic force acting on hull, the propeller thrust and the rudder force are calculated by the additional subroutine which interlock with the commercial simulation tool, and the regular <span class="hlt">wave</span> is used as the source of the external force for the simulation. Rudder rotational velocity and autopilot coefficients vary to make the different rudder controller. An advanced speed of ships depending on the rudder controller is analyzed after the autopilot simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/868595','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/868595"><span>Fiber-optic voltage sensor with cladded fiber and evanescent <span class="hlt">wave</span> <span class="hlt">variation</span> detection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wood, Charles B.</p> <p>1992-01-01</p> <p>A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent <span class="hlt">wave</span> in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7117654','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7117654"><span>Fiber-optic voltage sensor with cladded fiber and evanescent <span class="hlt">wave</span> <span class="hlt">variation</span> detection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wood, C.B.</p> <p>1992-12-15</p> <p>A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent <span class="hlt">wave</span> in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities. 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026667','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026667"><span>Shear <span class="hlt">wave</span> velocity <span class="hlt">variation</span> across the Taupo Volcanic Zone, New Zealand, from receiver function inversion</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bannister, S.; Bryan, C.J.; Bibby, H.M.</p> <p>2004-01-01</p> <p>The Taupo Volcanic Zone (TVZ), New Zealand is a region characterized by very high magma eruption rates and extremely high heat flow, which is manifest in high-temperature geothermal waters. The shear <span class="hlt">wave</span> velocity structure across the region is inferred using non-linear inversion of receiver functions, which were derived from teleseismic earthquake data. Results from the non-linear inversion, and from forward synthetic modelling, indicate low S velocities at ???6- 16 km depth near the Rotorua and Reporoa calderas. We infer these low-velocity layers to represent the presence of high-level bodies of partial melt associated with the volcanism. Receiver functions at other stations are complicated by reverberations associated with near-surface sedimentary layers. The receiver function data also indicate that the Moho lies between 25 and 30 km, deeper than the 15 ?? 2 km depth previously inferred for the crust-mantle boundary beneath the TVZ. ?? 2004 RAS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20866754','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20866754"><span>Generalized traveling-<span class="hlt">wave</span> method, <span class="hlt">variational</span> approach, and modified conserved quantities for the perturbed nonlinear Schrödinger equation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Quintero, Niurka R; Mertens, Franz G; Bishop, A R</p> <p>2010-07-01</p> <p>The generalized traveling <span class="hlt">wave</span> method (GTWM) is developed for the nonlinear Schrödinger equation (NLSE) with general perturbations in order to obtain the equations of motion for an arbitrary number of collective coordinates. Regardless of the particular ansatz that is used, it is shown that this alternative approach is equivalent to the Lagrangian formalism, but has the advantage that only the Hamiltonian of the unperturbed system is required, instead of the Lagrangian for the perturbed system. As an explicit example, we take 4 collective coordinates, namely the position, velocity, amplitude and phase of the soliton, and show that the GTWM yields the same equations of motion as the perturbation theory based on the Inverse Scattering Transform and as the time <span class="hlt">variation</span> of the norm, first moment of the norm, momentum, and energy for the perturbed NLSE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeoJI.181.1643R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeoJI.181.1643R"><span><span class="hlt">Variation</span> of coda <span class="hlt">wave</span> attenuation in the Alborz region and central Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rahimi, H.; Motaghi, K.; Mukhopadhyay, S.; Hamzehloo, H.</p> <p>2010-06-01</p> <p>More than 340 earthquakes recorded by the Institute of Geophysics, University of Tehran (IGUT) short period stations from 1996 to 2004 were analysed to estimate the S-coda attenuation in the Alborz region, the northern part of the Alpine-Himalayan orogen in western Asia, and in central Iran, which is the foreland of this orogen. The coda quality factor, Qc, was estimated using the single backscattering model in frequency bands of 1-25 Hz. In this research, lateral and depth <span class="hlt">variation</span> of Qc in the Alborz region and central Iran are studied. It is observed that in the Alborz region there is absence of significant lateral <span class="hlt">variation</span> in Qc. The average frequency relation for this region is Qc = 79 +/- 2f1.07+/-0.08. Two anomalous high-attenuation areas in central Iran are recognized around the stations LAS and RAZ. The average frequency relation for central Iran excluding the values of these two stations is Qc = 94 +/- 2f0.97+/-0.12. To investigate the attenuation <span class="hlt">variation</span> with depth, Qc value was calculated for 14 lapse times (25, 30, 35,... 90s) for two data sets having epicentral distance range R < 100 km (data set 1) and 100 < R < 200 km (data set 2) in each area. It is observed that Qc increases with depth. However, the rate of increase of Qc with depth is not uniform in our study area. Beneath central Iran the rate of increase of Qc is greater at depths less than 100 km compared to that at larger depths indicating the existence of a high attenuation anomalous structure under the lithosphere of central Iran. In addition, below ~180 km, the Qc value does not vary much with depth under both study areas, indicating the presence of a transparent mantle under them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25739713','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25739713"><span>Improving detection of obstructive sleep apnoea by overnight <span class="hlt">oximetry</span> in children using pulse rate parameters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sahadan, Dg Zuraini; Davey, Margot J; Horne, Rosemary S C; Nixon, Gillian M</p> <p>2015-12-01</p> <p>Overnight <span class="hlt">oximetry</span> is a simple tool for investigation of obstructive sleep apnoea (OSA) in children, but only severe cases will be detected, and children with obstructive events resulting in arousal, but not desaturation, will have a normal (inconclusive) result. We hypothesised that pulse rate rises using pulse rate indices per hour (PRI) and pulse rate standard deviation (PR-SD) automatically calculated from commercially available software would improve <span class="hlt">oximetry</span> as a diagnostic tool. Children having home overnight <span class="hlt">oximetry</span> for suspected OSA were identified over 12 months, and those with a normal result who went on to have polysomnography (PSG) were included. <span class="hlt">Oximetry</span>, including PR-SD and PRI (rises of 8, 10 and 15 beats/min per hour), was analyzed using commercially available software. PR parameters were compared between those with OSA (obstructive apnoea-hypopnoea index (OAHI) >1 event/h) and those without OSA. One hundred sixteen children had normal <span class="hlt">oximetry</span>, of whom 93 (median age 4.5 years; 55 % M) had PSG. Fifty-seven of 93 (61 %) children had OSA (median OAHI 4.5 events/h, range 1.1-24). PR-SD was not different between the OSA and non-OSA groups (p = 0.87). PRI tended to be higher in those with OSA, but there was considerable overlap between the groups: PRI-8 (mean ± SD 58.5 ± 29.0/h in OSA group vs 48.6 ± 20.2/h in non-OSA group, p = 0.07), PRI-10 (45.1 ± 25.0 vs 36.2 ± 16.7, p = 0.06) and PRI-15 (24.4 ± 14.5 vs 18.9 ± 9.0, p = 0.04). A PRI-15 threshold of >35/h had specificity of 97 % for OSA. The PRI-15 shows promise as an indicator of OSA in children with normal <span class="hlt">oximetry</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22128925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22128925"><span><span class="hlt">Variational</span> solution of the three-dimensional Schrödinger equation using plane <span class="hlt">waves</span> in adaptive coordinates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pérez-Jordá, José M</p> <p>2011-11-28</p> <p>A series of improvements for the solution of the three-dimensional Schrödinger equation over a method introduced by Gygi [F. Gygi, Europhys. Lett. 19, 617 (1992); F. Gygi, Phys. Rev. B 48, 11692 (1993)] are presented. As in the original Gygi's method, the solution (orbital) is expressed by means of plane <span class="hlt">waves</span> in adaptive coordinates u, where u is mapped from Cartesian coordinates, u=f(r). The improvements implemented are threefold. First, maps are introduced that allow the application of the method to atoms and molecules without the assistance of the supercell approximation. Second, the electron-nucleus singularities are exactly removed, so that pseudo-potentials are no longer required. Third, the sampling error during integral evaluation is made negligible, which results in a true <span class="hlt">variational</span>, second-order energy error procedure. The method is tested on the hydrogen atom (ground and excited states) and the H(2)(+) molecule, resulting in milli-Hartree accuracy with a moderate number of plane <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.6811M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.6811M"><span>Deriving daily and seasonal <span class="hlt">variations</span> in meteorological gravity <span class="hlt">wave</span> parameters from a tropical infrasound station and comparisons with lightning strike data form ATDnet and TRMM LIS.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marlton, Graeme; Charlton-Perez, Andrew; Harrison, Giles</p> <p>2017-04-01</p> <p>A wealth of work has shown that meteorological gravity <span class="hlt">wave</span> parameters can be derived from both satellite data and weather balloons. Satellite data has good temporal and spatial coverage but can only probe the lower stratosphere and mesosphere. Radiosonde wind and temperature profiles can also be used to infer gravity <span class="hlt">wave</span> information in the upper troposphere and lower stratosphere. Both methods have been used to investigate seasonal <span class="hlt">variations</span> in gravity <span class="hlt">wave</span> parameters at these heights. However, these methods cannot be used to infer gravity <span class="hlt">wave</span> parameters near the surface. One method to detect atmospheric gravity <span class="hlt">waves</span> at the surface is by using an infrasound array. Infrasound arrays consist of several microbarometers which are spaced kilometres apart. As the <span class="hlt">wave</span> passes over the array subtle pressure perturbations are subsequently detected at each microbarometer. The temporal differences in each microbarometer's time series allow a gravity <span class="hlt">wave</span>'s velocity, back azimuth, ground based frequency and amplitude to be calculated using the progressive multichannel correlation method. In order to calculate further meteorological values such as <span class="hlt">wave</span> number, velocity perturbations and hence find the momentum flux for each gravity <span class="hlt">wave</span>, data from meteorological station in close proximity to the array need to be combined with the infrasound data, which is explored here. Gravity <span class="hlt">wave</span> parameters calculated from infra sound data combined with meteorological data over several years will be shown for a station (IS17) in the Ivory Coast. Blanc et al 2010 showed an annual <span class="hlt">variation</span> in gravity <span class="hlt">wave</span> back azimuth due to the shifting of thunderstorms associated with the ITCZ. A spectral analysis of all gravity <span class="hlt">wave</span> parameters has revealed daily and seasonal <span class="hlt">variations</span>, which are further explored. To further understand the seasonal <span class="hlt">variations</span> observed data from the Tropical Rainfall Measurement Mission (TRMM) rainfall estimate and TRMM LIS lightning data are used to relate how the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23753242','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23753242"><span>Accuracy of noninvasive and continuous hemoglobin measurement by pulse co-<span class="hlt">oximetry</span> during preoperative phlebotomy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dewhirst, Elisabeth; Naguib, Aymen; Winch, Peter; Rice, Julie; Galantowicz, Mark; McConnell, Patrick; Tobias, Joseph D</p> <p>2014-01-01</p> <p>In recent years, the continuous noninvasive hemoglobin measurement has been offered by devices using advanced pulse <span class="hlt">oximetry</span> technology. Accuracy has been established in healthy adults as well as in surgical and intensive care unit patients but not in the setting of acute hemorrhage. In this study, we evaluated the accuracy of such a device in the clinical setting of preoperative phlebotomy thereby mimicking a scenario of acute blood loss. This prospective study included patients undergoing surgical repair of congenital heart disease (CHD) for whom preoperative phlebotomy was planned. Blood was removed after the induction of anesthesia and prior to the start of the surgical procedure. Replacement with crystalloid was guided by hemodynamic variables and cerebral oxygenation measured by near-infrared spectroscopy. Hemoglobin was measured by bedside whole blood analysis (total hemoglobin [tHb]) before and after phlebotomy, and concurrent measurements from the pulse co-oximeter (noninvasive, continuous, or spot-check testing of total hemoglobin [SpHb]) were recorded. The study cohort included 45 patients ranging in age from 3 months to 50 years. Preoperative phlebotomy removed an average of 9.2 mL/kg of blood that was replaced with an average of 7.2 mL/kg of crystalloid. The pre- and postphlebotomy tHb values were 13.0 ± 1.9 and 12.4 ± 1.8 g/dL, respectively. The absolute difference between the tHb and SpHb (▵Hb) was 1.2 ± 0.1 g/dL. Bland-Altman analysis revealed a bias of 0.1 g/dL, a precision of 1.5 g/dL, and 95% limits of agreement of -2.8 to 3.1 g/dL. In 52.2% of the sample sets, the SpHb was within 1 g/dL of the actual hemoglobin value (tHb), and in 80% of the sample sets, the SpHb was within 2 g/dL. No <span class="hlt">variation</span> in the accuracy of the deviation was noted based on the patient's age, weight, or type of CHD (cyanotic versus acyanotic). The current study demonstrates that the accuracy of continuous, noninvasive hemoglobin measurement was not affected by acute</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999EP%26S...51..675Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999EP%26S...51..675Y"><span>Seasonal <span class="hlt">variations</span> of 3.0˜3.8-day ultra-fast Kelvin <span class="hlt">waves</span> observed with a meteor wind radar and radiosonde in Indonesia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshida, S.; Tsuda, T.; Shimizu, A.; Nakamura, T.</p> <p>1999-07-01</p> <p>This paper is concerned with observations of the long-term behavior of Kelvin <span class="hlt">waves</span> with the <span class="hlt">wave</span> period ranging from 3 to 4 days, which are generally called an ultra-fast Kelvin (UFK) <span class="hlt">wave</span>. Horizontal wind velocity at 74-110 km altitudes observed with a meteor wind radar (MWR) near Jakarta (6.4°S, 106.7°E) for five years during November 1992 and December 1997 and daily radiosonde profiles in Bandung (6.9°S, 107.6°E) collected between October 1993 and March 1996 and have been analyzed. In the mesosphere and lower thermosphere (MLT) region, the UFK <span class="hlt">wave</span> activity, defined by the spectral density of zonal wind perturbations at the 3.0-3.8 day period, is strongly enhanced twice a year. An interaction between UFK <span class="hlt">waves</span> and a semiannual oscillation in the mesosphere (MSAO) can be suggested, although an exact mechanism is uncertain. We also have investigated seasonal <span class="hlt">variation</span> of 3.0-3.8 day oscillations of zonal winds in the stratosphere, excluding gravity <span class="hlt">wave</span> components, but, we have not detected an evidence of semiannual periodicity. The UFK <span class="hlt">wave</span> activity in the MLT region exhibited intraseasonal <span class="hlt">variations</span>, which showed some correlation with the amplitudes of zonal wind in the troposphere.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JaJAP..55fGP04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JaJAP..55fGP04L"><span>Toward efficient light diffraction and intensity <span class="hlt">variations</span> by using wide bandwidth surface acoustic <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Young Ok; Chen, Fu; Lee, Kee Keun</p> <p>2016-06-01</p> <p>We have developed acoustic-optic (AO) based display units for implementing a handheld hologram display by modulating light deflection through wide bandwidth surface acoustic <span class="hlt">wave</span> (SAW). The developed AO device consists of a metal layer, a ZnS waveguide layer, SAW inter digital transducers (IDTs), and a screen for display. When RF power with a particular resonant frequency was applied to IDTs, SAW was radiated and interfered with confined beam propagating along ZnS waveguide layer. The AO interacted beam was deflected laterally toward a certain direction depending on Bragg diffraction condition, exited out of the waveguide layer and then directed to the viewing screen placed at a certain distance from the device to form a single pixel. The deflected angles was adjusted by modulating the center frequency of the SAW IDT (SAW grating), the RF power of SAW, and the angles between propagating light beam path along waveguide and radiating SAW. The diffraction efficiency was also characterized in terms of waveguide thickness, SAW RF input power, and aperture length. Coupling of mode (COM) modeling was fulfilled to find optimal device parameters prior to fabrication. All the parameters affecting the deflection angle and efficiency to form a pixel for a three-dimensional (3D) hologram image were characterized and then discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ECSS...95..135N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ECSS...95..135N"><span>Secondary production in a Laminaria hyperborea kelp forest and <span class="hlt">variation</span> according to <span class="hlt">wave</span> exposure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norderhaug, Kjell M.; Christie, Hartvig</p> <p>2011-11-01</p> <p>The secondary production of mobile invertebrate fauna in the Laminaria hyperborea (Gunn.) Foslie kelp forest increases with <span class="hlt">wave</span> exposure level. This faunal group has a key function in transferring kelp carbon to higher levels in the food web. By using a size-frequency method the calculated production was 68 (±18) g D.W. m -2 yr -1 (±S.E.) at low, 250 (±57) at medium and 308 (±64) at high exposure levels. The calculations included 30 macrofauna species, which accounted for 96% of the specimens registered, with Gastropods, amphipods and bivalves being the most abundant taxa. The calculated secondary production is high, but comparable to that previously reported from other macrophyte systems and was 3%, 8% and 8% of the total primary production at low, medium and high exposure levels, respectively. Our results indicate that large quantities of Laminaria kelp are exported from the system, although the production of sessile animals was not taken into account. The most important factor in determining faunal densities and secondary production was probably habitat size but at low exposure levels the percentage of egg-carrying crustacean females and juveniles were lower than at medium and high exposure levels, thereby indicating lower fitness for animals at low exposure stations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1165L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1165L"><span>Interannual <span class="hlt">variation</span> of the quasi-two-day <span class="hlt">wave</span> at 22.7 S</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lima, Lourivaldo; Jacobi, Christoph; Batista, Paulo; Rodrigues de Araujo, Luciana; Rodrigues, Chayenny E. S.; Lilienthal, Friederike</p> <p>2016-07-01</p> <p>In the present investigation, the mesosphere/lower thermosphere winds at Cachoeira Paulista (22.7° S, 45.0° W) obtained by a VHF all sky interferometric meteor radar have been used to investigate the interannual variability of the quasi-two-day <span class="hlt">wave</span> (QTDW) amplitudes at a low latitude in the Southern Hemisphere. The wind data were obtained from December 1999 to July 2006, from September 2007 to October 2008 and from December 2013 to April 2015. The analysis shows that meridional amplitudes for QTDW are larger than zonal amplitudes and the strongest amplitudes occur after austral summer solstice in January-February. Besides semiannual and annual oscillations, the QTDW amplitudes in the meridional winds also show weak quasi-biennial oscillation (QBO). The summer QTDW in the meridional winds also shows a possible correlation with solar activity. The amplitudes are nearly in phase with the 11 year solar cycle, and the solar maxima leads the QTDW maxima by one year. Finally, larger QTDW amplifications have been observed during 2003, 2004, 2006 and 2015 summers. The unusual major sudden stratospheric warming (SSW) event suggests a coupling between QTDW amplification and SSW during Jan-Feb 2006. The mechanistic global circulation model MUAM of the middle and upper atmosphere has been used to simulate the dynamic configuration during January major and minor SSW events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21335807','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21335807"><span>Mixed augmented <span class="hlt">variational</span> formulation (MAVF) for lower hybrid full-<span class="hlt">wave</span> calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peysson, Y.; Roche, J. R.; Kirsch, C.; Mokrani, A.; Labrunie, S.; Bertrand, P.; Chatenet, J.-H.</p> <p>2009-11-26</p> <p>In the continuation of the works led in cylindrical geometry, a full toroidal description for an arbitrary poloidal cross-section of the plasma has been developed. For simulation purpose a mixed augmented <span class="hlt">variational</span> formulation (MAVF), which is particularly well suited for solving Maxwell equations, is considered. The discretization of the MAVF is carried out using Taylor-Hood P2-iso-P1 finite elements. This formulation provide a natural implementation for parallel processing, a particularly important aspect when simulations for plasmas of large size must be considered. Details on the specific application of the MAVF to the LH problem are presented, as well as the structure of the corresponding matrices. A first application to a realistic small tokamak configuration is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Tectp.708...70N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Tectp.708...70N"><span>Spatial <span class="hlt">variations</span> of seismic attenuation in the North West of Iranian plateau from analysis of coda <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naghavi, M.; Rahimi, H.; Moradi, A.; Mukhopadhyay, S.</p> <p>2017-06-01</p> <p>In this study, spatial <span class="hlt">variation</span> of coda <span class="hlt">wave</span> attenuation in the north western (NW) Iranian Plateau is explored using local earthquakes. Single backscattering method is used to map the spatial <span class="hlt">variations</span> of coda Q (Qc) using 14,969 earthquakes which are recorded digitally by sixteen permanent stations. Observed spatial attenuation maps are well correlated with geological setting of study area. North West of Iranian plateau is dominated with high attenuation which is well correlated with Quaternary deposits as well as the Sahnad, Sabalan volcanic zone and Tabriz fault. These observation is in accordance with numerous 2D velocity tomograms which have shown very low velocity in the NW Iran. The region characterized by volcanic structures exhibits mainly higher seismic attenuation than the surrounding regions whereas, Paleo Tethys basin in the eastern part of covered area are categorized by smaller attenuation than the other zone. Our observation shows good correlation with reported lower crustal low-velocity region beneath the Sahand and Sabalan volcanos. The Sahand and Sabalan volcanoes are very large structures and they dominate the Pliocene-Quaternary magmatic landscape of NW Iran. In addition, our observation has clearly shown existence of a probable fault zone trending in NE - SW direction between Tabriz city and Urmia Lake which is consistent with the trend of meizoseismal zone of the Deh-Khareqan (modern Azarshahr) earthquake (M 6.8) in 1641.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21548076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21548076"><span>Modular phenotypic plasticity: divergent responses of barnacle penis and feeding leg form to <span class="hlt">variation</span> in density and <span class="hlt">wave</span>-exposure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Neufeld, Christopher J</p> <p>2011-06-15</p> <p>Traits can evolve both in response to direct selection and in response to indirect selection on other linked traits. Although the evolutionary significance of coupled traits (e.g., through shared components of developmental pathways, or through competition for shared developmental resources) is now well accepted, we know comparatively little about how developmental coupling may restrict the independent responses of two or more phenotypically plastic traits in response to conflicting environmental cues. Such studies are important because coupled development, if present, could act as an important limit to the evolution of functionally independent plasticity in multiple traits. I tested whether developmental coupling can restrict the direction of plastic responses by studying how penis form and leg form--both highly plastic traits of barnacles--varied in response to differences in conspecific density and water velocity. Penis length and leg length in Balanus glandula varied in parallel with <span class="hlt">variation</span> in <span class="hlt">wave</span>-exposure but varied in opposite directions with <span class="hlt">variation</span> in conspecific density. This study represents one of the rare tests of developmental coupling between multiple (demonstrably adaptive) plastic traits: Barnacle legs and penises appear to exhibit modular development that can respond concurrently--yet in independent directions--to conflicting environmental cues. Copyright © 2011 Wiley-Liss, Inc., A Wiley Company.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4250...82Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4250...82Z"><span>Theoretical considerations to optimize transabdominal monitoring of fetal arterial blood oxygenation using pulse <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zourabian, Anna; Boas, David A.</p> <p>2001-06-01</p> <p>Pulse <span class="hlt">oximetry</span> (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse <span class="hlt">oximetry</span>. The wavelengths we chose as the most optimal are: the first in the range of 670-720nm and the second in the range of 825-925nm. Further we discuss the possible systematic errors during our measurements, and their contribution to the obtained saturation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10758188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10758188"><span>Comparison of dysphagics and nondysphagics on pulse <span class="hlt">oximetry</span> during oral feeding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Colodny, N</p> <p>2000-01-01</p> <p>This study was designed to determine whether significant differences in SpO(2) levels existed among elderly individuals with dysphagia, and, more specifically, whether pulse <span class="hlt">oximetry</span> can discriminate dysphagic from nondysphagic individuals. In addition, differences in SpO(2) between liquid aspirators, solid aspirators, laryngeal penetrators, and normals was investigated in a sample of 181 subjects, 104 of whom were dysphagic. Results indicated that aspirators had lower SpO(2) levels before, during, and after feeding compared with nonaspirators. Solid aspirators were the most compromised. No relation was found between SpO(2) levels and aspiration. Pulse levels rose for all subjects from before to during feeding, declining slightly thereafter. These data were consistent with previous findings that dysphagics have compromised pulmonary systems but at variance with studies that indicated changes in pulse <span class="hlt">oximetry</span> during aspiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19039914','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19039914"><span>[An updated review of methods for human retinal <span class="hlt">oximetry</span> measurements and current applications].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ben-Zion, Itay; Harris, Alon; Weizman, Yosi; Ehrlich, Rita; Rechtman, Ehud</p> <p>2008-10-01</p> <p>The concept of retinal <span class="hlt">oximetry</span> is based on physical properties that have been recognized since the 18th century. Attempts to non-invasively quantify the oxygen saturation of blood within the retinal vasculature date back to the 1950's. There are different techniques in existence for the measurement of retinal oxygenation, the leading ones are: photographic, digital, spectroscopy and the pulse methods. Each method has its advantages and disadvantages. Current data from studies on retinal <span class="hlt">oximetry</span> is presented, for both the healthy retina and in diseases such as glaucoma, diabetic retinopathy and age-related macular degeneration. It is clear that a thorough understanding of retinal oxygen tension is vital to our understanding of normal retinal physiology and the pathophysiology of degenerative eye diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CSR...115....1F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CSR...115....1F"><span>Spatiotemporal current <span class="hlt">variation</span> of coastal-trapped <span class="hlt">waves</span> west of the Noto Peninsula measured by using fishing boats</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukudome, Ken-ichi; Igeta, Yosuke; Senjyu, Tomoharu; Okei, Noriyuki; Watanabe, Tatsuro</p> <p>2016-03-01</p> <p>Spatiotemporal current <span class="hlt">variations</span> of coastal-trapped <span class="hlt">waves</span> (CTWs) were investigated by using a current dataset obtained from daily fishing operations west of the Noto Peninsula (NTP), Japan. Cross-shore lines located in southern, middle, and northern parts of the west coast of the NTP were designed to detect characteristics of CTWs with a time interval of a few days and about 5-km resolution in the cross-shore direction. Accuracy validation by using moored current meter data and sea level data demonstrated that the established dataset expresses accurate <span class="hlt">variations</span> with periods of several days. The generation and propagation of a CTW event associated with a low-pressure zone passing north of the study area in late May 2010 were analyzed. Along-shore currents with the coast on the right strengthened in every line simultaneously with the domination of the southerly wind, and then weakened in order from south to north simultaneously with weakening of the southerly wind. Although the along-shore currents of the CTWs linearly decreased heading offshore along the south and middle lines, these currents broadened within about 50 km from the coast along the north line, with small <span class="hlt">variations</span> in the cross-shelf direction, with an increase in shelf width. These generation, propagation and current structure characteristics are clarified and interpreted by the characteristics of the estimated possible CTWs west of the NTP and numerical experiments, which reproduce wind-induced freely propagating CTWs. A change in the propagation characteristics and the structure of the CTWs associated with bottom topography indicates the possibility that adjustments can occur on the order of a few dozen kilometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16238542','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16238542"><span>Indications and limitations for a neonatal pulse <span class="hlt">oximetry</span> screening of critical congenital heart disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rosati, Enrico; Chitano, Giovanna; Dipaola, Lucia; De Felice, Claudio; Latini, Giuseppe</p> <p>2005-01-01</p> <p>Critical congenital cardiovascular malformations (CCVMs) require surgical correction during the first month of life, physical examination is unable to detect >50% of affected infants. An <span class="hlt">oximetry</span> screening has been previously proposed. Our aim was to verify the usefulness and consistency of a pulse <span class="hlt">oximetry</span> screening for early detection of CCVMs in a small size nursery. A single determination of SpO2 was performed on 5292 consecutive apparently healthy newborns, discharged from nursery at a median age of 72 h during the period May 1, 2000 and November 30, 2004. Infants showing signs of congenital heart disease before the screening and those with a prenatal diagnosis were excluded. Cardiac ultrasound was performed on all infants with SpO2< or =95% at >24 h. The accuracy of the screening in identifying CCVMs was assessed by receiver-operating characteristic (ROC) curves analysis. We found 2 (0.038%) true positives, 1 (0.019%) false negative, 1 (0.019%) false positive, and 5288 (99.92%) true negatives. Prevalence of critical CCVMs was 1 in 1764. Clinical follow-up showed no evidence of CCVMs in the negative cases. A pulse-<span class="hlt">oximetry</span> cut-off value of < or =95% showed 66.7% sensitivity (95% CI: 11.6-94.5), 100% specificity (95% CI: 99.9-100.0), 50% positive predictive value, 100% negative predictive value and AUC of 0.833 (standard error: 0.145) (95% CI: 0.823 to 0.843) in identifying CCVMs. Our findings indicate that pulse <span class="hlt">oximetry</span> is a non-invasive and specific screening tool for an early detection of CCVMs, and is easily applicable to a small size nursery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9417E..0FV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9417E..0FV"><span>A rapid Look-Locker imaging sequence for quantitative tissue <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vidya Shankar, Rohini; Kodibagkar, Vikram D.</p> <p>2015-03-01</p> <p>Tissue <span class="hlt">oximetry</span> studies using magnetic resonance imaging are increasingly contributing to advances in the imaging and treatment of cancer. The non-invasive measurement of tissue oxygenation (pO2) may facilitate a better understanding of the pathophysiology and prognosis of diseases, particularly in the assessment of the extensive hypoxic regions associated with cancerous lesions. The availability of tumor hypoxia maps could help quantify and predict tumor response to intervention and therapy. The PISTOL (Proton Imaging of Siloxanes to map Tissue Oxygenation Levels) <span class="hlt">oximetry</span> technique maps the T1 of administered hexamethyldisiloxane (HMDSO), an 1H NMR pO2 reporter molecule in about 3 ½ min. This allows us to subsequently monitor static and dynamic changes in the tissue pO2 (in response to intervention) at various locations due to the linear relationship between 1/T1 and pO2. In this work, an HMDSO-selective Look-Locker imaging sequence with EPI readout has been developed to enable faster PISTOL acquisitions. The new sequence incorporates the fast Look-Locker measurement method to enable T1, and hence, pO2 mapping of HMDSO in under one minute. To demonstrate the application of this pulse sequence in vivo, 50 μL of neat HMDSO was administered to the thigh muscle of a healthy rat (Fischer F344, n=4). Dynamic changes in the mean pO2 of the thigh muscle were measured using both PISTOL and the developed LL <span class="hlt">oximetry</span> sequence in response to oxygen challenge and compared. Results demonstrate the efficacy of the new sequence in rapidly mapping the pO2 changes, leading to advances in fast quantitative 1H MR <span class="hlt">oximetry</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003SPIE.5138...29C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003SPIE.5138...29C"><span>Functional muscle studies by dual-wavelength eight-channel time-resolved <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cubeddu, Rinaldo; Biscotti, Giovanni; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Ferrari, Marco; Quaresima, Valentina</p> <p>2003-10-01</p> <p>A portable instrument for tissue <span class="hlt">oximetry</span> based on time-resolved reflectance spectroscopy was developed. The performances of the system were tested on phantoms in terms of stability, reproducibility among channels, and accuracy in the determination of the optical properties. Preliminary in vivo measurements were performed on healthy volunteers to monitor spatial changes in calf (medial and lateral gastrocnemius) oxygen hemoglobin saturation and blood volume during dynamic plantar flexion exercise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26129636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26129636"><span>Type III home sleep testing versus pulse <span class="hlt">oximetry</span>: is the respiratory disturbance index better than the oxygen desaturation index to predict the apnoea-hypopnoea index measured during laboratory polysomnography?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dawson, Arthur; Loving, Richard T; Gordon, Robert M; Abel, Susan L; Loewy, Derek; Kripke, Daniel F; Kline, Lawrence E</p> <p>2015-06-30</p> <p>In its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse <span class="hlt">oximetry</span>, but advises against simple pulse <span class="hlt">oximetry</span>. However, <span class="hlt">oximetry</span> is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on <span class="hlt">oximetry</span> alone with a stand-alone pulse oximeter (SPO) and from the <span class="hlt">oximetry</span> channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea-hypopnoea index (AHI) from laboratory polysomnography. Cross-sectional diagnostic accuracy study. Sleep medicine practice of a multispecialty clinic. Patients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP. Participants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODI(SOX)). For the ALP, RDI and ODI were calculated using both technician scoring (RDI(MAN) and ODI(MAN)) and the ALP computer scoring (RDI(RAW) and ODI(RAW)). The receiver-operator characteristic areas under the curve for AHI ≥ 5 were RDI(MAN) 0.88 (95% confidence limits 0.81-0.96), RDI(RAW) 0.86 (0.76-0.94), ODI(MAN) 0.86 (0.77-0.95), ODI(RAW) 0.84 (0.75-0.93) and ODI(SOX) 0.83 (0.73-0.93). We conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night <span class="hlt">variation</span> of the AHI. Published by the BMJ Publishing Group Limited. For permission to use (where not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4486950','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4486950"><span>Type III home sleep testing versus pulse <span class="hlt">oximetry</span>: is the respiratory disturbance index better than the oxygen desaturation index to predict the apnoea-hypopnoea index measured during laboratory polysomnography?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dawson, Arthur; Loving, Richard T; Gordon, Robert M; Abel, Susan L; Loewy, Derek; Kripke, Daniel F; Kline, Lawrence E</p> <p>2015-01-01</p> <p>Objectives In its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse <span class="hlt">oximetry</span>, but advises against simple pulse <span class="hlt">oximetry</span>. However, <span class="hlt">oximetry</span> is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on <span class="hlt">oximetry</span> alone with a stand-alone pulse oximeter (SPO) and from the <span class="hlt">oximetry</span> channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea–hypopnoea index (AHI) from laboratory polysomnography. Design Cross-sectional diagnostic accuracy study. Setting Sleep medicine practice of a multispecialty clinic. Participants Patients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP. Interventions Participants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODISOX). For the ALP, RDI and ODI were calculated using both technician scoring (RDIMAN and ODIMAN) and the ALP computer scoring (RDIRAW and ODIRAW). Results The receiver–operator characteristic areas under the curve for AHI ≥5 were RDIMAN 0.88 (95% confidence limits 0.81–0.96), RDIRAW 0.86 (0.76–0.94), ODIMAN 0.86 (0.77–0.95), ODIRAW 0.84 (0.75–0.93) and ODISOX 0.83 (0.73–0.93). Conclusions We conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night <span class="hlt">variation</span> of the AHI. PMID</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23852744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23852744"><span>An Electronic Patch for wearable health monitoring by reflectance pulse <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haahr, Rasmus G; Duun, Sune B; Toft, Mette H; Belhage, Bo; Larsen, Jan; Birkelund, Karen; Thomsen, Erik V</p> <p>2012-02-01</p> <p>We report the development of an Electronic Patch for wearable health monitoring. The Electronic Patch is a new health monitoring system incorporating biomedical sensors, microelectronics, radio frequency (RF) communication, and a battery embedded in a 3-dimensional hydrocolloid polymer. In this paper the Electronic Patch is demonstrated with a new optical biomedical sensor for reflectance pulse <span class="hlt">oximetry</span> so that the Electronic Patch in this case can measure the pulse and the oxygen saturation. The reflectance pulse <span class="hlt">oximetry</span> solution is based on a recently developed annular backside silicon photodiode to enable low power consumption by the light emitting components. The Electronic Patch has a disposable part of soft adhesive hydrocolloid polymer and a reusable part of hard polylaurinlactam. The disposable part contains the battery. The reusable part contains the reflectance pulse <span class="hlt">oximetry</span> sensor and microelectronics. The reusable part is 'clicked' into the disposable part when the patch is prepared for use. The patch has a size of 88 mm by 60 mm and a thickness of 5 mm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27140658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27140658"><span>Oxygen saturation and perfusion index from pulse <span class="hlt">oximetry</span> in adult volunteers with viable incisors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kong, Hyoun-Joong; Shin, Teo Jeon; Hyun, Hong-Keun; Kim, Young-Jae; Kim, Jung-Wook; Shon, Won-Jun</p> <p>2016-07-01</p> <p>Evaluation of pulp vitality is an important diagnostic procedure in dentistry. Conventional techniques for measurement of pulp vitality, including thermal stimulation, electrical stimulation, or direct dentin stimulation, are frequently associated with false positive or false negative results. Recently, oxygen saturation from pulse <span class="hlt">oximetry</span> has been utilized in the evaluation of pulp vitality. Perfusion index (PI) data calculated from photoplethysmography have been widely used to evaluate peripheral perfusion. The combination of oxygen saturation and PI may aid in the accurate measurement of pulp vitality. We aimed to investigate the baseline values of oxygen saturation and PI using pulse <span class="hlt">oximetry</span> in adult volunteers. Fifteen adult volunteers with viable incisors were tested. To measure PI, a fabricated oxygen sensor was applied to an incisor without a pulp lesion while oxygen saturation was simultaneously measured in the finger. Oxygen saturation and PI were continuously measured with customized software. The normal reference values of oxygen saturation and PI were obtained by analyzing the recorded data. Pulse <span class="hlt">oximetry</span> showed relatively stable, objective, and accurate oxygen saturation results. The tooth oxygen saturation ranged from 97% to 100%. The PI ranged from 0.3% to 0.5%, and PI and oxygen saturation showed relatively consistent values across subjects. Although there are some limitations to our study, these results may prove useful for detecting teeth with impaired vitality and non-invasively differentiating between necrotic and vital pulp.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27807379','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27807379"><span>Validation of noninvasive hemoglobin measurements using co-<span class="hlt">oximetry</span> in anesthetized dogs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Read, Matt R; Rondeau, Jenna; Kwong, Grace P S</p> <p>2016-11-01</p> <p>New technology allows noninvasive measurement of total hemoglobin (Hb) in humans through use of multiple wavelength co-<span class="hlt">oximetry</span>. This monitor is now available to the veterinary market but no studies have been performed to validate its use in animals. This study investigated the use of co-<span class="hlt">oximetry</span> to measure Hb in anesthetized dogs by comparing "gold standard" Hb measurements from a laboratory (LabHb) with those measured by the co-oximeter (SpHb). Bland-Altman analysis showed that the monitor had a bias of -3.01 (SpHb values were lower than LabHb values) and that 64.5% of measured SpHb values were greater than 20 g/L different from their associated LabHb values. Based on the results of this study, use of co-<span class="hlt">oximetry</span> to measure Hb in anesthetized dogs is not accurate enough to direct treatment. Further studies are warranted in other animal species and under other clinical conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8599297','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8599297"><span>Notes on the apparent discordance of pulse <span class="hlt">oximetry</span> and multi-wavelength haemoglobin photometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nijland, R; Jongsma, H W; Nijhuis, J G; Oeseburg, B; Zijlstra, W G</p> <p>1995-01-01</p> <p>Multi-wavelength photometers, blood gas analysers and pulse oximeters are widely used to measure various oxygen-related quantities. The definitions of these quantities are not always correct. This paper gives insight in the various definitions for oxygen quantities. Furthermore, the possible influences of dyshaemoglobins and fetal haemoglobin on the accuracy of pulse <span class="hlt">oximetry</span> are discussed. As pulse oximeters are constructed for the determination of arterial oxygen saturation, they should be validated with sample oxygen saturation values and not with the oxyhaemoglobin fraction. The influence of carboxyhaemoglobin is insubstantial over an oxygen saturation range of 0% to 100%. Through the presence of methaemoglobin, pulse <span class="hlt">oximetry</span> will give an underestimation above 70% and an overestimation below 70% oxygen saturation. The influence of fetal haemoglobin is insignificant in the neonatal use of pulse <span class="hlt">oximetry</span>, in the range of 75% to 100% arterial oxygen saturation. However, a pulse oximeter underestimates the arterial oxygen saturation at the 25% level with 5%, if the pulse oximeter has been calibrated in human adults. Such a low level of arterial oxygen saturation can be present in the fetus during labor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4029673','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4029673"><span>Calibration-Free Pulse <span class="hlt">Oximetry</span> Based on Two Wavelengths in the Infrared — A Preliminary Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nitzan, Meir; Noach, Salman; Tobal, Elias; Adar, Yair; Miller, Yaacov; Shalom, Eran; Engelberg, Shlomo</p> <p>2014-01-01</p> <p>The assessment of oxygen saturation in arterial blood by pulse <span class="hlt">oximetry</span> (SpO2) is based on the different light absorption spectra for oxygenated and deoxygenated hemoglobin and the analysis of photoplethysmographic (PPG) signals acquired at two wavelengths. Commercial pulse oximeters use two wavelengths in the red and infrared regions which have different pathlengths and the relationship between the PPG-derived parameters and oxygen saturation in arterial blood is determined by means of an empirical calibration. This calibration results in an inherent error, and pulse <span class="hlt">oximetry</span> thus has an error of about 4%, which is too high for some clinical problems. We present calibration-free pulse <span class="hlt">oximetry</span> for measurement of SpO2, based on PPG pulses of two nearby wavelengths in the infrared. By neglecting the difference between the path-lengths of the two nearby wavelengths, SpO2 can be derived from the PPG parameters with no need for calibration. In the current study we used three laser diodes of wavelengths 780, 785 and 808 nm, with narrow spectral line-width. SaO2 was calculated by using each pair of PPG signals selected from the three wavelengths. In measurements on healthy subjects, SpO2 values, obtained by the 780–808 nm wavelength pair were found to be in the normal range. The measurement of SpO2 by two nearby wavelengths in the infrared with narrow line-width enables the assessment of SpO2 without calibration. PMID:24763216</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JBO.....5..391Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JBO.....5..391Z"><span>Trans-abdominal monitoring of fetal arterial blood oxygenation using pulse <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zourabian, Anna; Siegel, Andrew M.; Chance, Britton; Ramanujam, Nirmala; Rode, Martha; Boas, David A.</p> <p>2000-10-01</p> <p>Pulse <span class="hlt">oximetry</span> (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both the fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse <span class="hlt">oximetry</span>. The wavelengths we chose as the most optimal are the first in the range of 670 - 720 nm and the second in the range of 825 - 925 nm. Further, we discuss the possible systematic errors during our measurements and their contribution to the obtained saturation results. We present feasibility studies for fetal pulse <span class="hlt">oximetry</span>, monitored noninvasively through the maternal abdomen. Our preliminary experiments show that the fetal pulse can be discriminated from the maternal pulse and thus, in principle, the fetal arterial oxygen saturation can be obtained. We present the methodology for obtaining these data, and discuss the dependence of our measurements on the fetal position with respect to the optode assembly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26002141','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26002141"><span>Intravenous injection of indocyanine green results in an artificial transient desaturation by pulse <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ediriwickrema, Lilangi S; Francis, Jasmine H; Arslan-Carlon, Vittoria; Dalecki, Paul H; Brodie, Scott E; Marr, Brian P; Abramson, David H</p> <p>2015-01-01</p> <p>To describe a case series of transient oxygen desaturation measured by pulse <span class="hlt">oximetry</span> during the intravenous infusion of indocyanine green to enhance transpupillary thermotherapy in treating retinoblastoma after ophthalmic artery chemosurgery. Retrospective descriptive case series. The intravenous administration of indocyanine green for ophthalmic angiography resulted in a transient drop in oxygen saturation as measured by Nellcor fingertip pulse <span class="hlt">oximetry</span> in three children with retinoblastoma receiving indocyanine green-guided transpupillary thermotherapy. The magnitude of reduction ranged from 92% to 94% from an initial reading of 99% to 100% in each case, with an average duration of 3 minutes. Concurrent measurement of blood pressure, pulse, and expired CO2 showed no changes during this process. Administration of intravenous indocyanine green resulted in a transient desaturation by <span class="hlt">oximetry</span> during transpupillary thermotherapy for children with retinoblastoma under anesthesia because of the fluorescent dye's absorption of red light in a manner similar to that of deoxygenated hemoglobin, thereby leading to transient instrument misinterpretation and miscalculation of arterial oxygenation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24588079','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24588079"><span>Clinical examination and pulse <span class="hlt">oximetry</span> as screening for congenital heart disease in low-risk newborn.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zuppa, Antonio Alberto; Riccardi, Riccardo; Catenazzi, Piero; D'Andrea, Vito; Cavani, Maria; D'Antuono, Annamaria; Iafisco, Alma; Romagnoli, Costantino</p> <p>2015-01-01</p> <p>To assess sensitivity, specificity, positive predictive value and negative predictive value of the cardiovascular physical examination (CPE) and of pulse <span class="hlt">oximetry</span> in screening for congenital heart diseases (CHD) in asymptomatic newborn when prenatal ultrasound evaluation is negative for structural cardiac abnormalities. In this observational cohort study, 5750 asymptomatic newborns, admitted to nursery in a period of 2 years, underwent to CPE and determination of arterial oxygen saturation by pulse oxymetry between 48th and 72nd h of life. Two hundred and ninty-eight newborns presented a suspected CPE; in 70% of cases, we found a transitional alteration and in only 17% of cases, the echocardiography examination performed for suspected CPE were completely negative. Three newborns were positive to pulse <span class="hlt">oximetry</span> screening test but negative at CPE. After discharge, one case of critical CHD was diagnosed. An accurate CPE performed by trained and experienced pediatricians is indicative of important cardiac structural alteration in more than 25%. The association of CPE and pulse <span class="hlt">oximetry</span> allows to further improve the diagnostic accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24056207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24056207"><span>The effect of simulated cataract light scatter on retinal vessel <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patel, Sunni R; Hudson, Chris; Flanagan, John G; Heitmar, Rebekka</p> <p>2013-11-01</p> <p>To assess the impact of light scatter, similar to that introduced by cataract on retinal vessel blood oxygen saturation measurements using poly-bead solutions of varying concentrations. Eight healthy, young, non-smoking individuals were enrolled for this study. All subjects underwent digital blood pressure measurements, assessment of non-contact intraocular pressure, pupil dilation and retinal vessel <span class="hlt">oximetry</span> using dual wavelength photography (<span class="hlt">Oximetry</span> Module, Imedos Systems, Germany). To simulate light scatter, cells comprising a plastic collar and two plano lenses were filled with solutions of differing concentrations (0.001, 0.002 and 0.004%) of polystyrene microspheres (Polysciences Inc., USA). The adopted light scatter model showed an artifactual increase in venous optical density ratio (p = 0.036), with the 0.004% condition producing significantly higher venous optical density ratio values when compared to images without a cell in place. Spectrophotometric analysis, and thus retinal vessel <span class="hlt">oximetry</span> of the retinal vessels, is altered by artificial light scatter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JMiMi..20g5020D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JMiMi..20g5020D"><span>High quantum efficiency annular backside silicon photodiodes for reflectance pulse <span class="hlt">oximetry</span> in wearable wireless body sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duun, Sune; Haahr, Rasmus G.; Hansen, Ole; Birkelund, Karen; Thomsen, Erik V.</p> <p>2010-07-01</p> <p>The development of annular photodiodes for use in a reflectance pulse <span class="hlt">oximetry</span> sensor is presented. Wearable and wireless body sensor systems for long-term monitoring require sensors that minimize power consumption. We have fabricated large area 2D ring-shaped silicon photodiodes optimized for minimizing the optical power needed in reflectance pulse <span class="hlt">oximetry</span>. To simplify packaging, backside photodiodes are made which are compatible with assembly using surface mounting technology without pre-packaging. Quantum efficiencies up to 95% and area-specific noise equivalent powers down to 30 fW Hz-1/2 cm-1 are achieved. The photodiodes are incorporated into a wireless pulse <span class="hlt">oximetry</span> sensor system embedded in an adhesive patch presented elsewhere as 'The Electronic Patch'. The annular photodiodes are fabricated using two masked diffusions of first boron and subsequently phosphor. The surface is passivated with a layer of silicon nitride also serving as an optical filter. As the final process, after metallization, a hole in the center of the photodiode is etched using deep reactive ion etch.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.4442T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.4442T"><span>Features of amplitude and Doppler frequency <span class="hlt">variation</span> of ELF/VLF <span class="hlt">waves</span> generated by "beat-<span class="hlt">wave</span>" HF heating at high latitudes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tereshchenko, E. D.; Shumilov, O. I.; Kasatkina, E. A.; Gomonov, A. D.</p> <p>2014-07-01</p> <p>Observations of extremely low frequency (ELF, 3-3000 Hz) radio <span class="hlt">waves</span> generated by a "beat-<span class="hlt">wave</span>" (BW) high frequency (~ 4.04-4.9 MHz) ionospheric heating are presented. ELF <span class="hlt">waves</span> were registered with the ELF receiver located at Lovozero (68°N, 35°E), 660 km east from the European Incoherent Scatter Tromso heating facility (69.6°N, 19.2°E). Frequency shifts between the generated beat-<span class="hlt">wave</span> and received ELF <span class="hlt">waves</span> were detected in all sessions. It is shown that the amplitudes of ELF <span class="hlt">waves</span> depend on the auroral electrojet current strength. Our results showing a strong dependence of ELF signal intensities on the substorm development seem to support the conclusion that electrojet currents may affect the BW generation of ELF/VLF <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeoJI.187..355M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeoJI.187..355M"><span>Global seismic body-<span class="hlt">wave</span> observations of temporal <span class="hlt">variations</span> in the Earth's inner core, and implications for its differential rotation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mäkinen, Anna M.; Deuss, Arwen</p> <p>2011-10-01</p> <p>Differential rotation of the Earth's inner core has been predicted in some geodynamo models, and seismic studies over the past 15 yr have resolved rotation rates up to 1° yr-1. Most previous seismic body-<span class="hlt">wave</span> studies have focussed on South Sandwich Islands events recorded at station COL in Alaska. Here, we present a globally extended study into temporal <span class="hlt">variations</span> in the inner core over some 25 yr, using PKPbc-PKPdf traveltime residuals. To test for differential rotation of the inner core, displacement of inner-core heterogeneities over time is sought. We introduce a new method of space-flattening to remove the effect of spatial <span class="hlt">variations</span> on the time <span class="hlt">variations</span>; this allows for the use of both polar, semi-equatorial and equatorial geometries. First, we reanalyse polar paths from South Sandwich Islands events to stations COL and INK in North America. These stations yield a differential rotation of the inner core at a rate of 0.12-0.38° yr-1 in an eastward direction, in agreement with previous studies. However, station DAWY, which has a very similar path through the inner core as COL, yields at best a westward differential rotation of the inner core. Thus DAWY results are incompatible with the COL/INK inferred rotation. Secondly, earthquakes in the Aleutian Islands region, observed at BOSA and LBTB in southern Africa, exhibit temporal <span class="hlt">variations</span> that are incompatible with the South Sandwich Islands-COL/INK inferred rotation rate. Thirdly, Kuril Islands events, recorded in South America at station BDF, yield inconclusive results. Finally, our final piece of evidence for the irreconcilability of differential inner-core rotation with global data comes from using earthquakes in the Vanuatu region, recorded at BCAO/BGCA in Central Africa, an equatorial geometry. These residuals resolve a westward inner-core rotation at a rate of 0.14° yr-1, over the same time period that South Sandwich Islands events indicate an eastward rotation. As any rigid-body rotation should</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1211M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1211M"><span>Effects of the gravitational <span class="hlt">waves</span> emission on the orbit of the binary neutron stars considering the mass <span class="hlt">variation</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mabrouk, Zeinab; Rahoma, W. A.</p> <p>2016-07-01</p> <p>Gravitational <span class="hlt">waves</span> which have been announced finally to be detected in February 11, 2016 are believed to be emitted from many sources and phenomena in the universe, the binary neutron stars systems specially the inspirals are one kind of them. In this paper we are going to calculate the effects of this emission on the elements of the elliptical orbits of such binary neutron stars before the onset of the mass exchange. We based our work on the Imshennik and Popov (1994) paper then we do some modifications. The main and important results that Imshennik and Popov get were the rate of change of the eccentricity e, the rate of change of the semi major axis a, and the monotonic dependence between them a=a(e). Finally they concluded the smallness of the final eccentricity which make the orbits to be near-circular due to the emission of the gravitational <span class="hlt">waves</span>. Our modification is to consider the masses of the two binary stars to be varied using the famous Eddington-Jeams law, then we expand them around the time t using Taylor expansion. we do this <span class="hlt">variation</span> first for one mass with the constancy of the second one, then we let both mosses to vary together. We start the algorithm from the beginning substituting with our new series of masses in the two main equations, the average rate of change of the total energy of the system (dE/dt) , and the average rate of change of the angular momentum (dJ/dt). This modification leads to new expressions of the previous mentioned rate of changes of the orbital elements obtained by Imshennik and Popov, some of them we obtained and still working in the rest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11094776','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11094776"><span>Next-generation pulse <span class="hlt">oximetry</span>. Focusing on Masimo's signal extraction technology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>2000-10-01</p> <p>Pulse oximeters are used to determine trends in patients' blood oxygen saturation and to warn of dangerous saturation levels. But conventional pulse <span class="hlt">oximetry</span> has some inherent limitations. For example, it has difficulty monitoring patients who are moving or who have poor perfusion; it is also subject to interference from certain visible and infrared light sources. Over the past several years, a number of companies have developed advanced signal-processing techniques that allow pulse oximeters to overcome many of these limitations. We refer to such new technologies as next-generation pulse <span class="hlt">oximetry</span>. In this Evaluation, we focus on the first next-generation technology to have reached the market: Masimo Corporation's Signal Extraction Technology (SET). We designed our study of Masimo SET to address the main question that needs to be asked of any next-generation technology: How well does it compare to conventional pulse <span class="hlt">oximetry</span>? Specifically, how well does it perform when a patient is moving or being moved, when a patient is poorly perfused, or when certain types of light strike the sensor while it is attached to or detached from the patient? We also examined one type of sensor used with this product, comparing it to conventional tape-on sensors for comfort and durability. Several other next-generation pulse-oximeter products have become available since we began this study. We are currently evaluating these products and will publish our findings in the near future. A list of the products, including a brief description of each, is included in this article. Pulse oximeters are used to determine trends in patients' blood oxygen saturation and to warn against dangerous saturation levels. These monitors are often vital in helping to ensure patient safety, especially for critically ill patients, pediatric patients, and neonates. But conventional pulse <span class="hlt">oximetry</span> has some inherent limitations--most significantly, it has difficulty monitoring patients who are moving or who have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20815194','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20815194"><span>Comparison between a single-channel nasal airflow device and <span class="hlt">oximetry</span> for the diagnosis of obstructive sleep apnea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rofail, Lydia Makarie; Wong, Keith K H; Unger, Gunnar; Marks, Guy B; Grunstein, Ronald R</p> <p>2010-08-01</p> <p>The most common single channel devices used for obstructive sleep apnea (OSA) screening are nasal airflow and <span class="hlt">oximetry</span>. No studies have directly compared their role in diagnosing OSA at home. To prospectively compare the diagnostic utility of home-based nasal airflow and <span class="hlt">oximetry</span> to attended polysomnography (PSG) and to assess the diagnostic value of adding <span class="hlt">oximetry</span> to nasal airflow for OSA. Cross-sectional study. Laboratory and home. Sleep clinic patients with suspected OSA. All patients had laboratory PSG and 2 sets of 3 consecutive nights on each device; nasal airflow (Flow Wizard, DiagnoselT, Australia) and <span class="hlt">oximetry</span> (Radical Set, Masimo, USA) at home in random order. Ninety-eight of the 105 patients enrolled completed home monitoring. The accuracy of nasal airflow respiratory disturbance index (NF RDI) was not different from <span class="hlt">oximetry</span> (ODI 3%) for diagnosing OSA (area under the ROC curve (AUC) difference, 0.04; 95% CI of difference -0.05 to 0.12; P = 0.43) over 3 nights of at-home recording. The accuracy of NF RDI was higher after 3 nights compared to one night (AUC difference, 0.05; 95% CI of difference, 0.01 to 0.08; P = 0.04). Addition of <span class="hlt">oximetry</span> to nasal airflow did not increase the accuracy for predicting OSA compared to nasal airflow alone (P > 0.1). Nasal flow and <span class="hlt">oximetry</span> have equivalent accuracy for diagnosing OSA in the home setting. Choice of device for home screening of sleep apnea may depend on logistical and service delivery issues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeoRL..38.4308K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeoRL..38.4308K"><span>Short-scale <span class="hlt">variations</span> of shear-<span class="hlt">wave</span> splitting across the Dead Sea basin: Evidence for the effects of sedimentary fill</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaviani, Ayoub; Rümpker, Georg; Weber, Michael; Asch, Günter</p> <p>2011-02-01</p> <p>We examine shear-<span class="hlt">wave</span> splitting of SKS waveforms collected by a temporary array of 68 stations in the region of the Dead Sea basin. The observed splitting parameters exhibit systematic <span class="hlt">variations</span> along a dense, EW-trending 60 km profile across the basin. The delay times vary significantly between 1.0 and 2.8 seconds with smaller values in the very center of the profile. The fast polarizations are oriented more-or-less parallel to the strike of the Dead Sea transform fault and vary between -10 and 20 degrees with respect to North. Finite-frequency waveform modeling reveals that the source-region of the small-scale lateral <span class="hlt">variations</span> is likely located within the crust. The modeling further shows that purely isotropic velocity <span class="hlt">variations</span> affect shear-<span class="hlt">wave</span> splitting: To a large degree, the observed <span class="hlt">variations</span> of splitting parameters can be explained by the sedimentary fill of the basin and its low isotropic seismic velocities, whereas the mantle is uniformly anisotropic. Our study indicates that precaution must be taken when interpreting short-scale lateral <span class="hlt">variations</span> of shear <span class="hlt">wave</span> splitting in terms of anisotropic structures in the crust or upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27317046','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27317046"><span>In vivo <span class="hlt">oximetry</span> of human bulbar conjunctival and episcleral microvasculature using snapshot multispectral imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacKenzie, L E; Choudhary, T R; McNaught, A I; Harvey, A R</p> <p>2016-08-01</p> <p>Multispectral imaging (MSI) is a well-established technique for non-invasive <span class="hlt">oximetry</span> of retinal blood vessels, which has contributed to the understanding of a variety of retinal conditions, including glaucoma, diabetes, vessel occlusion, and retinal auto-regulation. We report the first study to use snapshot multi-spectral imaging (SMSI) for <span class="hlt">oximetry</span> of the bulbar conjunctival and episcleral microvasculature in the anterior segment of the eye. We report the oxygen dynamics of the bulbar conjunctival and episcleral microvasculature at normoxia and at acute mild hypoxia conditions. A retinal-fundus camera fitted with a custom Image-Replicating Imaging Spectrometer was used to image the bulbar conjunctival and episcleral microvasculature in ten healthy human subjects at normoxia (21% Fraction of Inspired Oxygen [FiO2]) and acute mild hypoxia (15% FiO2) conditions. Eyelid closure was used to control oxygen diffusion between ambient air and the sclera surface. Four subjects were imaged for 30 seconds immediately following eyelid opening. Vessel diameter and Optical Density Ratio (ODR: a direct proxy for oxygen saturation) of vessels was computed automatically. <span class="hlt">Oximetry</span> capability was validated using a simple phantom that mimicked the scleral vasculature. Acute mild hypoxia resulted in a decrease in blood oxygen saturation (SO2) (i.e. an increase in ODR) when compared with normoxia in both bulbar conjunctival (p < 0.001) and episcleral vessels (p = 0.03). Average episcleral diameter increased from 78.9 ± 8.7 μm (mean ± standard deviation) at normoxia to 97.6 ± 14.3 μm at hypoxia (p = 0.02). Diameters of bulbar conjunctival vessels showed no significant change from 80.1 ± 7.6 μm at normoxia to 80.6 ± 7.0 μm at hypoxia (p = 0.89). When exposed to ambient air, hypoxic bulbar conjunctival vessels rapidly reoxygenated due to oxygen diffusion from ambient air. Reoxygenation occured in an exponential manner, and SO2 reached normoxia baseline levels. The average </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSA41B..09N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSA41B..09N"><span>Longitudinal <span class="hlt">Variation</span> in GPS -TEC and Topside Electron Density Associated with the <span class="hlt">Wave</span> Number Four Structures over South American Sector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nogueira, P. A.; Abdu, M. A.; Souza, J. R.; Bailey, G. J.; Shume, E. B.; Denardini, C. M.</p> <p>2012-12-01</p> <p>Recent observations of the low-latitude ionospheric electron density have revealed a longitudinal structure in the Equatorial Ionization Anomaly (EIA) intensity, which is characterized by a <span class="hlt">wave</span> number-four pattern when plotted at a constant-local-time frame. It has been proposed that neutral wind driven dynamo electric fields from the E-region due to non migrating tidal modes are responsible for this pattern. In the present work we have used measurements from the Defense Meteorological Satellite Program (DMSP) to investigate the four peaks structure in the topside electron density of the low latitude ionosphere. We also compare the climatology of the Total Electron Content (TEC) as observed by GPS receivers in two equatorial stations over South America, São Luís (2.33 S, 315.8E, declination = -19 degree) in Brazil and Arequipa (16.5S, 288.5E, declination = 0.5 degree) in Peru. TEC <span class="hlt">variations</span> for three solar activity levels (high, moderate and low) have been analyzed. TEC values over São Luís are found to be larger than that ones over Arequipa independent of the season, local time and solar cycle conditions. We estimated the vertical plasma drifts over these stations using magnetometer data during daytime and using ionosonde data for evening hours. We fed the Sheffield University Plasmasphere Ionosphere Model (SUPIM) with this drifts in an attempt to partially explain the differences in the TEC over these stations. The SUPIM was also used to evaluate the effect of thermospheric wind to cause the four peaks structure in the plasma density. Therefore, we analyze the equatorial ionospheric response to combined effects of thermospheric neutral winds and zonal electric field causing the longitudinal <span class="hlt">variation</span> in TEC observed in the South American longitude sector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21612483','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21612483"><span>Lower Hybrid <span class="hlt">Wave</span> Induced SOL Emissivity <span class="hlt">Variation</span> at High Density on the Alcator C-Mod Tokamak</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Faust, I.; Terry, J. L.; Reinke, M. L.; Meneghini, O.; Shiraiwa, S.; Wallace, G. M.; Parker, R. R.; Schmidt, A. E.; Wilson, J. R.</p> <p>2011-12-23</p> <p>Lower Hybrid Current Drive (LHCD) in the Alcator C-Mod tokamak provides current profile control for the generation of Advanced Tokamak (AT) plasmas. Non-thermal electron bremsstrahlung emission decreases dramatically at n-bar{sub e}>1{center_dot}10{sup 20}[m{sup -3}] for diverted discharges, indicating low current drive efficiency. It is suggested that Scrape-Off-Layer (SOL) collisional absorption of LH <span class="hlt">waves</span> is the cause for the absence of non-thermal electrons at high density. VUV and visible spectroscopy in the SOL provide direct information on collision excitation processes. Deuterium Balmer-, Lyman- and He-I transition emission measurements were used for initial characterization of SOL electron-neutral collisional absorption. Data from Helium and Deuterium LHCD discharges were characterized by an overall increase in the emissivity as well as an outward radial shift in the emissivity profile with increasing plasma density and applied LHCD power. High-temperature, high-field (T{sub e} = 5keV,B{sub t} = 8T) helium discharges at high density display increased non-thermal signatures as well as reduced SOL emissivity. <span class="hlt">Variations</span> in emissivity due to LHCD were seen in SOL regions not magnetically connected to the LH Launcher, indicating global SOL effects due to LHCD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20095666','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20095666"><span><span class="hlt">Variational</span> solution of the Schrödinger equation using plane <span class="hlt">waves</span> in adaptive coordinates: The radial case.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pérez-Jordá, José M</p> <p>2010-01-14</p> <p>A new method for solving the Schrödinger equation is proposed, based on the following details. First, a map u=u(r) from Cartesian coordinates r to a new coordinate system u is chosen. Second, the solution (orbital) psi(r) is written in terms of a function U depending on u so that psi(r)=/J(u)/(-1/2)U(u), where /J(u)/ is the Jacobian determinant of the map. Third, U is expressed as a linear combination of plane <span class="hlt">waves</span> in the u coordinate, U(u)= sum (k)c(k)e(ik x u). Finally, the coefficients c(k) are <span class="hlt">variationally</span> optimized to obtain the best energy, using a generalization of an algorithm originally developed for the Coulomb potential [J. M. Perez-Jorda, Phys. Rev. B 58, 1230 (1998)]. The method is tested for the radial Schrödinger equation in the hydrogen atom, resulting in micro-Hartree accuracy or better for the energy of ns and np orbitals (with n up to 5) using expansions of moderate length.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25405691','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25405691"><span>A review of signal processing used in the implementation of the pulse <span class="hlt">oximetry</span> photoplethysmographic fluid responsiveness parameter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Addison, Paul S</p> <p>2014-12-01</p> <p>ΔPOP is a physiological parameter derived from the respiration-induced change in the pulse <span class="hlt">oximetry</span> plethysmographic (POP) waveform or "pleth." It has been proposed as a proxy for pulse pressure <span class="hlt">variation</span> used in the determination of the response to intravascular volume expansion in hypovolemic patients. Many studies have now reported on the parameter, and many research groups have constructed algorithms for its computation from the first principles where the implementation details have been described. This review focuses on the signal processing aspects of ΔPOP, as reported in the literature, and aims to provide a comprehensive summary of the wide-ranging algorithmic strategies that have been attempted in its computation. A search was conducted for articles concerning the use of ΔPOP as a fluid responsiveness parameter. In particular, articles concerning the correlation between ΔPOP and pulse pressure <span class="hlt">variation</span> were targeted. Comments and replies to comments by the authors in which signal processing aspects were discussed were also included in the review. The parameter is first defined, and a history of the early work surrounding pleth-based fluid responsiveness parameters is presented. This is followed by an overview of the signal processing methods used in the reported studies, including details of exclusion criteria, manual filtering (preprocessing), gain change issues, acquisition details, selection of registration periods, averaging methods, physiological influences on the pleth, and comments by the investigators themselves. It is concluded that to develop a robust, fully automated ΔPOP algorithm for use in the clinical environment, more rigorous signal processing is required. Specifically, signals should be evaluated over significant periods of time, with emphasis on the quality and temporal relevance of the information.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26498244','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26498244"><span>The role of nocturnal pulse <span class="hlt">oximetry</span> in the screening for obstructive sleep apnea in obese children and adolescents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Eyck, Annelies; Lambrechts, Chinouk; Vanheeswijck, Liesbeth; Van Hoorenbeeck, Kim; Haentjens, Dominique; Boudewyns, An; De Winter, Benedicte Y; Van Gaal, Luc; De Backer, Wilfried; Verhulst, Stijn L</p> <p>2015-11-01</p> <p>Obesity is a known risk factor for the development of obstructive sleep apnea (OSA) in children. Early screening is essential because of the possible complications associated with OSA. At present, the gold standard for diagnosing OSA is polysomnography, which however has multiple limitations. The aim of this study is to examine the role of nocturnal <span class="hlt">oximetry</span> as a screening tool for OSA in obese children and adolescents. This retrospective study included obese children who underwent a polysomnography at the Antwerp University Hospital between November 2010 and May 2014. Their <span class="hlt">oximetries</span> were scored manually, blinded for the polysomnography results, according to Brouilette et al. OSA was defined as an obstructive apnea-hypopnea index (oAHI) ≥ 2 on polysomnography. This study included 130 obese patients (38% boys, mean age 12 years). Polysomnography results determined 44 patients (34%) with a diagnosis of OSA. <span class="hlt">Oximetry</span> results classified 16 patients as positive, 43 as negative, and 71 as inconclusive. Further analysis of the positive and negative <span class="hlt">oximetry</span> results showed a sensitivity and specificity of 58% and 88%, respectively, with a negative and positive predictive value of 81% and 69%, respectively. A second analysis, using the oxygen desaturation index, showed inferior results in comparison to the score attained by Brouillette (sensitivity 57%, specificity 73%). These results suggest that <span class="hlt">oximetry</span> alone is insufficient as a screening tool for OSA in obese children. Other screening methods need to be explored in the future. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25241768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25241768"><span>Effectiveness of pulse-<span class="hlt">oximetry</span> in addition to routine neonatal examination in detection of congenital heart disease in asymptomatic newborns.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oakley, Juliette L; Soni, Naharmal B; Wilson, Dirk; Sen, Siddhartha</p> <p>2015-01-01</p> <p>To assess the feasibility and effectiveness of pulse-<span class="hlt">oximetry</span> as a screening tool in the detection of critical congenital heart disease (CCHD) in newborns. Post-natal babies born between 01/01/2007-31/12/2009 were eligible. Post-ductal pulse-<span class="hlt">oximetry</span> was performed using Nellcor® NPB 40 pulse oximeter with reusable OXI-A/N saturation probe. Saturations ≥95% were deemed normal. If saturations were <95%, an echocardiogram was done. The regional paediatric cardiology database and death records identified babies later diagnosed with CCHD. 6329/9613 eligible babies were studied and pulse-<span class="hlt">oximetry</span> was performed at a mean age of 28 hours (range 6-72 hours). Fourteen babies had saturations <95%. CCHD was diagnosed in 7/14 babies; 4/7 had no clinical signs. Of the remaining 7 babies, 3 had non-critical but significant CHD and 4 had an undiagnosed respiratory illness or sepsis. All babies with low saturations had identifiable pathologies. One baby with normal saturations was later diagnosed with transposition of the great arteries. The sensitivity and specificity of identifying an unwell baby was 93.3% and 100% respectively; the sensitivity and specificity of identifying CCHD was 87.5% and 99.8% respectively. Clinical examination alone would have missed 4/7 (57%) of these. Pulse-<span class="hlt">oximetry</span> is safe, acceptable, non-invasive and effective. Our study supports the routine use of pulse <span class="hlt">oximetry</span> as part of the newborn check.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22170511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22170511"><span>Oxygen and pulse <span class="hlt">oximetry</span> in childhood pneumonia: a survey of healthcare providers in resource-limited settings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ginsburg, Amy Sarah; Van Cleve, William C; Thompson, Mary I W; English, Mike</p> <p>2012-10-01</p> <p>Globally, pneumonia is the leading cause of death in children <5 years of age. Hypoxemia, a frequent complication of pneumonia, is a risk factor for death. To better understand the availability of oxygen and pulse <span class="hlt">oximetry</span>, barriers to use and provider perceptions and practices regarding their role in childhood pneumonia, we conducted a survey using a convenience sampling strategy targeting clinicians working in resource-limited countries. Most respondents were physicians from public district and provincial hospitals with access to oxygen and pulse <span class="hlt">oximetry</span>; however, reported therapeutic use for childhood pneumonia was low. Common barriers included insufficient supply, competition for use, lack of policies, guidelines and training and perceived high cost. Despite the frequency of hypoxemia, the inaccuracy of clinical predictors, the poor outcome hypoxemia portends and the effectiveness of pulse <span class="hlt">oximetry</span> and oxygen in childhood pneumonia, our data indicate that these tools may be underused in resource-limited settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28685459','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28685459"><span>Using India Ink as a Sensor for <span class="hlt">Oximetry</span>: Evidence of its Safety as a Medical Device.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flood, Ann Barry; Wood, Victoria A; Swartz, Harold M</p> <p>2017-01-01</p> <p>Clinical EPR spectroscopy is emerging as an important modality, with the potential to be used in standard clinical practice to determine the extent of hypoxia in tissues and whether hypoxic tissues respond to breathing enriched oxygen during therapy. <span class="hlt">Oximetry</span> can provide important information useful for prognosis and to improve patient outcomes. EPR <span class="hlt">oximetry</span> has many potential advantages over other ways to measure oxygen in tissues, including directly measuring oxygen in tissues and being particularly sensitive to low oxygen, repeatable, and non-invasive after an initial injection of the EPR-sensing material is placed in the tumor. The most immediately available oxygen sensor is India ink, where two classes of carbon (carbon black and charcoal) have been identified as having acceptable paramagnetic properties for <span class="hlt">oximetry</span>. While India ink has a long history of safe use in tattoos, a systematic research search regarding its safety for marking tissues for medical uses and an examination of the evidence that differentiates between ink based on charcoal or carbon black has not been conducted. Using systematic literature search techniques, we searched the PubMed and Food and Drug Administration databases, finding ~1000 publications reporting on adverse events associated with India/carbon based inks. The detailed review of outcomes was based on studies involving >16 patients, where the ink was identifiable as carbon black or charcoal. Fifty-six studies met these criteria. There were few reports of complications other than transient and usually mild discomfort and bleeding at injection, and there was no difference in charcoal vs. carbon black India ink. India ink was generally well tolerated by patients and physicians reported that it was easy to use in practice and used few resources. The risk is low enough to justify its use as an oxygen sensor in clinical practice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18500050','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18500050"><span>Pulse <span class="hlt">oximetry</span> in the preflight evaluation of patients with chronic obstructive pulmonary disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Akerø, Aina; Christensen, Carl C; Edvardsen, Anne; Ryg, Morten; Skjønsberg, Ole H</p> <p>2008-05-01</p> <p>In a British Thoracic Society (BTS) statement on preflight evaluation of patients with respiratory disease, sea level pulse <span class="hlt">oximetry</span> (Spo2sl) is recommended as an initial assessment. The present study aimed to evaluate if the BTS algorithm can be used to identify chronic obstructive pulmonary disease (COPD) patients in need of supplemental oxygen during air travel, i.e. patients with an in-flight PaO2 < 6.6 kPa (50 mmHg). There were 100 COPD patients allocated to groups according to the BTS algorithm: Spo2sl > 95%, Spo2sl 92-95% without additional risk factors; Spo2sl 92-95% with additional risk factors; Spo2sl < 92%; and patients using domiciliary oxygen. Pulse <span class="hlt">oximetry</span>, arterial blood gases, and an hypoxia-altitude simulation test (HAST) to simulate a cabin altitude of 2438 m (8000 ft), were performed. The percentage of patients in the various groups dropping below 6.6 kPa during HAST were: Spo2sl > 95%: 30%; Spo2sl 92-95% without additional risk factors: 67%; Spo2sl 92-95% with additional risk factors: 70%; Spo2sl < 92%: 83%; and patients using domiciliary oxygen: 81%. In patients dropping below P(a)o(2) 6.6 kPa, supplemental oxygen of median 1 L x min(-1) was needed to exceed this limit. If in-flight P(a)o(2) > or = 6.6 kPa is regarded as a strict requirement, the use of pulse <span class="hlt">oximetry</span> as an initial assessment in the preflight evaluation of COPD patients, as suggested by the BTS, might not discriminate adequately between patients who fulfill the indications for supplemental oxygen during air travel, and patients who can travel without such treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23594686','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23594686"><span>Rapid implementation of pulse <span class="hlt">oximetry</span> newborn screening to detect critical congenital heart defects - New Jersey, 2011.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p></p> <p>2013-04-19</p> <p>In August 2011, New Jersey implemented a statewide newborn screening protocol for critical congenital heart defects (CCHD) using pulse <span class="hlt">oximetry</span>. In January 2012, CDC responded to a request from the New Jersey Department of Health (NJDOH) to assist with an assessment of the implementation. Out of the 52 birthing facilities in New Jersey, a sample of 11 was selected. Staff interviews were conducted to assess screening and data collection processes, data flow and tracking procedures, electronic medical record (EMR) capabilities, and capacity to report data to NJDOH. Feedback also was obtained about the questionnaire being used to follow-up on positive screening results. All 11 facilities were screening for CCHD. Among the 11 facilities, three were electronically entering and maintaining data into an EMR, five were manually entering and maintaining data into paper charts and logs, and three were both electronically and manually entering and maintaining data. Facilities reported that implementation of newly mandated CCHD screening posed a low burden to hospital staff members. NJDOH receives aggregate pulse <span class="hlt">oximetry</span> screening data from all New Jersey birthing facilities. During the first 3 months of screening, preliminary data indicated that 98.2% of 25,214 newborns were screened. Hospitals reported data on 12 newborns with positive screening results; two newborns were newly diagnosed with CCHD as a result of pulse <span class="hlt">oximetry</span> screening. Because of state-specific factors, such as out-of-state referral patterns, these findings might underestimate the anticipated number of positive screens in states with varying referral patterns and use of prenatal diagnosis. Rapid implementation of universal CCHD screening posed a relatively low burden to hospitals in New Jersey.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23493292','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23493292"><span>The impact of flash intensity on retinal vessel oxygen saturation measurements using dual wavelength <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heitmar, Rebekka; Cubbidge, Robert Peter</p> <p>2013-04-17</p> <p>To establish the optimal flash settings for retinal vessel oxygen saturation parameters using dual-wavelength imaging in a multiethnic group. Twelve healthy young subjects (mean age 32 years [SD 7]; three Mediterranean, two South Asian, and seven Caucasian individuals) underwent retinal vessel oxygen saturation measurements using dual-wavelength <span class="hlt">oximetry</span>, noncontact tonometry, and manual sphygmomanometry. In order to evaluate the impact of flash intensity, we obtained three images (fundus camera angle 30°, ONH centered) per flash setting. Flash settings of the fundus camera were increased in steps of 2 (initial setting of 6 and the final of 22), which reflect logarithmic increasing intensities from 13.5 to 214 Watt seconds (Ws). Flash settings below 27 Ws were too low to obtain saturation measurements, whereas flash settings of more than 214 Ws resulted in overexposed images. Retinal arteriolar and venular oxygen saturation was comparable at flash settings of 27 to 76 Ws (arterioles' range: 85%-92%; venules' range: 45%-53%). Higher flash settings lead to increased saturation measurements in both retinal arterioles (up to 110%) and venules (up to 92%), with a more pronounced increase in venules. Flash intensity has a significant impact on retinal vessel oxygen saturation measurements using dual-wavelength retinal <span class="hlt">oximetry</span>. High flash intensities lead to supranormal oxygen saturation measurements with a magnified effect in retinal venules compared with arteries. In addition to even retinal illumination, the correct flash setting is of paramount importance for clinical acquisition of images in retinal <span class="hlt">oximetry</span>. We recommend flash settings between 27 to 76 Ws.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28672762','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28672762"><span>Critical congenital heart disease screening with a pulse <span class="hlt">oximetry</span> in neonates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hamilçıkan, Şahin; Can, Emrah</p> <p>2017-06-27</p> <p>To compare the results of pulse <span class="hlt">oximetry</span> screening for critical congenital heart disease (CCHD) in newborn infants performed at <24 h and >24 h following. Measurements were taken for each group at <24 h and >24 h following birth. Echocardiography was performed if the SpO2 readings remained abnormal results. A total of 4518 newborns were included in this prospective descriptive study. Of these, 2484 (60.3%) were delivered vaginally and 1685 (39.7%) by cesarean section. Median time points of the screening were 25.4 (25.3-25.5) vs. 17.3 (12.2-22.4) hours after birth. In 4109 infants screened 24 h after birth, the mean pre- and postductal oxygen saturations (SpO2) were 96.5±1.99 and 97.7±1.98, while 127 infants screened within 24 h of mean preductal and postductal SpO2 were 91.33±2.64 and 94.0±4.44. No CCHD was detected during the study period. Pulse <span class="hlt">oximetry</span> screening was false positive for CCHD in 9 of 4109 infants (0.02%); of these, six infants were referred to pediatric cardiology and three cases were diagnosed as other significant, non-cardiac pathology. There were two cases with AVSD (atrioventricular septal defect, three cases with ventricular septal defect (VSD), and one case with patent ductus arteriosus (PDA). Saturation values are different between <24-h and >24-h neonates in pulse <span class="hlt">oximetry</span> screening. The screening in this study identified infants with other important pathologies, this forms an added value as an assessment tool for newborn infants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.T33B1361H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.T33B1361H"><span>Segment-Scale <span class="hlt">Variations</span> in Crustal Thickness Along the Southeast Indian Ridge From 2-D Body <span class="hlt">Wave</span> Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holmes, R.; Tolstoy, M.; Cochran, J. R.</p> <p>2004-12-01</p> <p>The Southeast Indian Ridge (SEIR) west of the Australian Antarctic Discordance (AAD) exhibits a nearly constant intermediate spreading rate (72-76 mm/yr) and dredge sample basalt geochemistry despite systematic changes observed in the depth and morphology of the ridge axis. These unique conditions make it possible to investigate how <span class="hlt">variations</span> in melt production (or equivalently, crustal thickness) correlate with axial morphology along the SEIR. A total of six seismic refraction experiments were conducted along SEIR segments P1, P2, S1, and T as part of R/V Maurice Ewing cruise EW0114 (Dec 2001-Jan 2002). The 100-125 km lines were positioned above zero- age crust for all four segments as well as 20 km south of the axis (~525 ka) for segments P1 and P2. In each survey, four ocean bottom hydrophones deployed 15-20 km apart recorded shots fired by the 8480 in3 20-gun airgun array. P <span class="hlt">wave</span> travel times for crustal refractions (Pg) and Moho reflections (PmP) were hand-picked and assigned error values ranging from 15-150 ms based on the trace signal-to-noise ratio. Starting with 1-D crustal velocity-depth profiles, we constructed an overparameterized 2-D inverse problem and derived minimum structure solutions by regularizing the inversion with predefined damping and smoothness constraints. The forward step calculated ray travel times by combining shortest path (graph) method results with a beta-spline ray- bending refinement scheme. We applied a top-down methodology to the inversion, including picks from progressively larger instrument offsets with each iteration to account for the dominant influence of upper crustal heterogeneity on travel time <span class="hlt">variations</span>. Our preferred models show a consistent thinning of the crust toward the AAD coincident with the transition from a robust axial high (P1) to a well-developed axial valley (T). We performed a direct assessment of model resolution using checkerboard tests, nonlinear Monte Carlo analysis, and a variable depth kernel</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.T33B1361H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.T33B1361H"><span>Segment-Scale <span class="hlt">Variations</span> in Crustal Thickness Along the Southeast Indian Ridge From 2-D Body <span class="hlt">Wave</span> Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holmes, R.; Tolstoy, M.; Cochran, J. R.</p> <p>2007-12-01</p> <p>The Southeast Indian Ridge (SEIR) west of the Australian Antarctic Discordance (AAD) exhibits a nearly constant intermediate spreading rate (72-76 mm/yr) and dredge sample basalt geochemistry despite systematic changes observed in the depth and morphology of the ridge axis. These unique conditions make it possible to investigate how <span class="hlt">variations</span> in melt production (or equivalently, crustal thickness) correlate with axial morphology along the SEIR. A total of six seismic refraction experiments were conducted along SEIR segments P1, P2, S1, and T as part of R/V Maurice Ewing cruise EW0114 (Dec 2001-Jan 2002). The 100-125 km lines were positioned above zero- age crust for all four segments as well as 20 km south of the axis (~525 ka) for segments P1 and P2. In each survey, four ocean bottom hydrophones deployed 15-20 km apart recorded shots fired by the 8480 in3 20-gun airgun array. P <span class="hlt">wave</span> travel times for crustal refractions (Pg) and Moho reflections (PmP) were hand-picked and assigned error values ranging from 15-150 ms based on the trace signal-to-noise ratio. Starting with 1-D crustal velocity-depth profiles, we constructed an overparameterized 2-D inverse problem and derived minimum structure solutions by regularizing the inversion with predefined damping and smoothness constraints. The forward step calculated ray travel times by combining shortest path (graph) method results with a beta-spline ray- bending refinement scheme. We applied a top-down methodology to the inversion, including picks from progressively larger instrument offsets with each iteration to account for the dominant influence of upper crustal heterogeneity on travel time <span class="hlt">variations</span>. Our preferred models show a consistent thinning of the crust toward the AAD coincident with the transition from a robust axial high (P1) to a well-developed axial valley (T). We performed a direct assessment of model resolution using checkerboard tests, nonlinear Monte Carlo analysis, and a variable depth kernel</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyB..497...51N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyB..497...51N"><span>Energies and <span class="hlt">wave</span> functions of an off-centre donor in hemispherical quantum dot: Two-dimensional finite difference approach and ritz <span class="hlt">variational</span> principle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakra Mohajer, Soukaina; El Harouny, El Hassan; Ibral, Asmaa; El Khamkhami, Jamal; Assaid, El Mahdi</p> <p>2016-09-01</p> <p>Eigenvalues equation solutions of a hydrogen-like donor impurity, confined in a hemispherical quantum dot deposited on a wetting layer and capped by an insulating matrix, are determined in the framework of the effective mass approximation. Conduction band alignments at interfaces between quantum dot and surrounding materials are described by infinite height barriers. Ground and excited states energies and <span class="hlt">wave</span> functions are determined analytically and via one-dimensional finite difference approach in case of an on-center donor. Donor impurity is then moved from center to pole of hemispherical quantum dot and eigenvalues equation is solved via Ritz <span class="hlt">variational</span> principle, using a trial <span class="hlt">wave</span> function where Coulomb attraction between electron and ionized donor is taken into account, and by two-dimensional finite difference approach. Numerical codes developed enable access to <span class="hlt">variations</span> of donor total energy, binding energy, Coulomb correlation parameter, spatial extension and radial probability density with respect to hemisphere radius and impurity position inside the quantum dot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3502464','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3502464"><span>Acute <span class="hlt">Variations</span> in Retinal Vascular Oxygen Content in a Rabbit Model of Retinal Venous Occlusion</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Saati, Saloomeh; Martin, Gabriel; Chader, Gerald; Humayun, Mark S.</p> <p>2012-01-01</p> <p>Purpose To study the <span class="hlt">variation</span> in intravascular oxygen saturation (<span class="hlt">oximetry</span>) during an acute retinal vein occlusion (RVO) using hyperspectral computed tomographic spectroscopy based <span class="hlt">oximetry</span> measurements. Methods Thirty rabbits were dilated and anesthetized for experiments. Baseline <span class="hlt">oximetry</span> measurements were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a fundus camera. RVO were induced using argon green laser following an intravenous injection of Rose Bengal. RVO induction was confirmed by fluorescein angiography. Retinal <span class="hlt">oximetry</span> measurements were repeated in arterial and venous branches one hour after RVO induction and up to 4 weeks afterwards. Comparison of retinal <span class="hlt">oximetry</span> before and after vein occlusion was made using the Student T-test. Results One hour after RVO induction, we observed statistically significant reductions in the intravascular oxygen saturation in temporal retinal arteries (85.1±6.1% vs. 80.6±6.6%; p<0.0001) and veins (71.4±5.5% vs. 64.0±4.7%; p<0.0001). This decrease was reversible in animals that spontaneously recannulated the vein occlusion. There were no statistically significant differences in oxygen saturation in the nasal control arteries and veins before and after temporal vein RVO induction. Conclusions We demonstrate, for the first time, acute changes in the intravascular oxygen content of retinal vessels 1 hour after RVO. These changes are reversible upon spontaneous recannulation of retinal vessels. This study demonstrates that hyperspectral computer tomographic spectroscopy based <span class="hlt">oximetry</span> can detect physiological <span class="hlt">variations</span> in intravascular retinal oxygen saturation. The study also provides the first qualitative and quantitative evidence of the <span class="hlt">variation</span> in retinal vascular oxygen content directly attributable to an acute retinal vein occlusion. PMID:23185567</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDM20004D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDM20004D"><span>Transition of torque pattern in undulatory locomotion due to <span class="hlt">wave</span> number <span class="hlt">variation</span> in resistive force dominated media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, Yang; Ming, Tingyu</p> <p>2016-11-01</p> <p>In undulatory locomotion, torque (bending moment) is required along the body to overcome the external forces from environments and bend the body. Previous observations on animals using less than two wavelengths on the body showed such torque has a single traveling <span class="hlt">wave</span> pattern. Using resistive force theory model and considering the torque generated by external force in a resistive force dominated media, we found that as the <span class="hlt">wave</span> number (number of wavelengths on the locomotor's body) increases from 0.5 to 1.8, the speed of the traveling <span class="hlt">wave</span> of torque decreases. When the <span class="hlt">wave</span> number increases to 2 and greater, the torque pattern transits from a single traveling <span class="hlt">wave</span> to a two traveling <span class="hlt">waves</span> and then a complex pattern that consists two <span class="hlt">wave</span>-like patterns. By analyzing the force distribution and its contribution to the torque, we explain the speed decrease of the torque <span class="hlt">wave</span> and the pattern transition. This research is partially supported by the Recruitment Program of Global Young Experts (China).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780051431&hterms=very+short+time+series&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dvery%2Bshort%2Btime%2Bseries','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780051431&hterms=very+short+time+series&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dvery%2Bshort%2Btime%2Bseries"><span>Modulation of short <span class="hlt">waves</span> by long <span class="hlt">waves</span>. [ocean <span class="hlt">wave</span> interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reece, A. M., Jr.</p> <p>1978-01-01</p> <p><span class="hlt">Wave</span>-tank experiments were performed to investigate the cyclic short-<span class="hlt">wave</span> energy changes, related in phase to an underlying long <span class="hlt">wave</span>, which occur during active generation of the short-<span class="hlt">wave</span> field by wind. Measurements of time series of the short-<span class="hlt">wave</span> slope were made by a laser-optical system, where the basic long-<span class="hlt">wave</span> parameters were controlled and wind speeds were accurately reproducible. The short-<span class="hlt">wave</span> slope variances were found to exhibit cyclic <span class="hlt">variations</span> that are related to the phase of the long <span class="hlt">wave</span>. The <span class="hlt">variations</span> result from two combined effects: (1) the short <span class="hlt">wave</span> frequency is varied by the long-<span class="hlt">wave</span> orbital velocity; (2) the energy of the short <span class="hlt">waves</span> is modulated by the actions of aerodynamic and hydrodynamic couplings that operate on the short <span class="hlt">waves</span> in a manner related to the long-<span class="hlt">wave</span> phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8656L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8656L"><span>Evaluating future flooding risks by using a probabilistic approach to include <span class="hlt">wave</span> height distributions in sea level <span class="hlt">variations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leijala, Ulpu; Björkqvist, Jan-Victor; Kahma, Kimmo K.; Johansson, Milla M.; Pellikka, Hilkka; Särkkä, Jani</p> <p>2016-04-01</p> <p>Assessing sea flood risks has an essential role in future coastal planning as climate change drives forward the global sea level rise. Safe planning of land utilization and building in coastal areas requires capability to estimate sea level behaviour all the way to 100-200 years ahead. The coastal effect of the sea level is always affected also by the <span class="hlt">wave</span> conditions, which may vary greatly depending on location. An archipelago acts as an efficient shield against the largest <span class="hlt">waves</span> penetrating to the shoreline. However, part of the energy of the <span class="hlt">waves</span> passes through the archipelago and coastal <span class="hlt">wave</span> height conditions, depending for example on the shape of the shoreline and topography of the seabed, must be evaluated close to the shore separately. The probability of high sea level and wind generated high <span class="hlt">waves</span> occurring simultaneously is lower than the probability of one of the components occurring alone. Summing the maximum sea level and maximum <span class="hlt">wave</span> height components together can thus lead to an overestimation of the joint effect. For this reason a method based on probability distributions is reasonable and preferable. In this study, a method of combining sea level and <span class="hlt">wave</span> height distributions using a location specific probability approach is introduced. First estimates of the joint effect of high sea level and high <span class="hlt">waves</span> at several locations at the archipelago area on the southern coast of Finland are presented. Constructing sea level scenarios including the effect of wind <span class="hlt">waves</span> until the end of the century demands knowledge of both sea level and <span class="hlt">wave</span> height variability in the past, and global mean sea level predictions for the future. In our study, an estimate of short-term sea level variability is based on 30 years (1982-2011) of hourly data from the Helsinki tide gauge located on the coast of the Gulf of Finland. Future predictions for the long-term mean sea level changes at Helsinki are based on scenarios taking into account the global mean sea level rise</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24796364','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24796364"><span>TELEMOLD project: <span class="hlt">oximetry</span> and exercise telemonitoring to improve long-term oxygen therapy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Faria, Inês; Gaspar, Carina; Zamith, Manuela; Matias, Isabel; das Neves, Rui César; Rodrigues, Fátima; Bárbara, Cristina</p> <p>2014-07-01</p> <p>Standard assessment of long-term oxygen therapy (LTOT) prescription involves hospital-based clinical tests. However, there is some evidence suggesting that oxygen demand during daily activities may not be correctly estimated by such tests, when compared with continuous ambulatory <span class="hlt">oximetry</span>. The authors describe the results of a study aiming to evaluate the clinical relevance of a home telemonitoring system in LTOT optimization. Thirty-five chronic respiratory failure patients were monitored in real time with an oximeter sensor and an accelerometer. Signals were sent via Bluetooth(®) (Bluetooth SIG, Kirkland, WA) to a mobile phone and then via 3G or general packet radio service to a server. Continuous and secure access to data was established through an Internet site. Each patient was monitored an average of 7.6 ± 4.5 days (total, 83 ± 67 h). Valid records were on average 65 ± 24%. Records of rest, activity, and sleep time per patient were, on average, 28 ± 21%, 7 ± 6%, and 59 ± 25%, respectively. Significant desaturation during rest, activity, and sleep was found in 2, 26, and 9 patients, respectively. Patients' ratings of the user-friendliness of the equipments, assessed by questionnaire, were fairly good (76% reported it as easy/very easy). Our study suggests that a telemonitoring system combining <span class="hlt">oximetry</span> and physical activity evaluation might contribute to a more adequate oxygen prescription, mainly during daily activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25269325','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25269325"><span>[Wavelength selection of the <span class="hlt">oximetry</span> based on test analysis of variance].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Ling; Li, Wei; Zeng, Rui-Li; Liu, Rui-An; Li, Gang; Wu, Xiao-Rong</p> <p>2014-07-01</p> <p>In order to improve the precision and reliability of the spectral measurement of blood oxygen saturation, and enhance the validity of the measurement, the method of test analysis of variance was employed. Preferred wavelength combination was selected by the analysis of the distribution of the coefficient of <span class="hlt">oximetry</span> at different wavelength combinations and rational use of statistical theory. Calculated by different combinations of wavelengths (660 and 940 nm, 660 and 805 nm and 805 and 940 nm) through the clinical data under different oxygen saturation, the single factor test analysis of variance model of the oxygen saturation coefficient was established, the relative preferabe wavelength combination can be selected by comparative analysis of different combinations of wavelengths from the photoelectric volume pulse to provide a reliable intermediate data for further modeling. The experiment results showed that the wavelength combination of 660 and 805 nm responded more significantly to the changes in blood oxygen saturation and the introduced noise and method error were relatively smaller of this combination than other wavelength combination, which could improve the measurement accuracy of <span class="hlt">oximetry</span>. The study applied the test variance analysis to the selection of wavelength combination in the blood oxygen result measurement, and the result was significant. The study provided a new idea for the blood oxygen measurements and other related spectroscopy quantitative analysis. The method of test analysis of variance can help extract the valid information which represents the measured values from the spectrum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19041637','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19041637"><span>Hydroxocobalamin and cyanocobalamin interference on co-<span class="hlt">oximetry</span> based hemoglobin measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pamidi, Prasad V A; DeAbreu, Marlene; Kim, Donghak; Mansouri, Sohrab</p> <p>2009-03-01</p> <p>Hydroxocobalamin (OHCbl) and cyanocobalamin (CNCbl) are dark-red colored analogs of vitamin B-12. OHCbl is used as an alternate antidote for cyanide poisoning. Due to the strong red color, if uncorrected, these cobalamins interfere with hemoglobin measurements and can introduce errors in spectrophotometric assay on co-oximeters. The impact of cobalamins on commonly used co-<span class="hlt">oximetry</span> systems was compared to evaluate the accuracy of hemoglobin measurements and to further assess the ability of the instruments to detect and flag cobalamin interference. Blood samples spiked with varying concentrations of hydroxocobalamin or cyanocobalamin (0-2 g/l), were measured on 3 GEM Premier 4000 s, 3 IL 682 CO-Oximeter, 1 Radiometer ABL 735 and 1 Siemens Rapidpoint 405 analyzer. The effect of OHCbl or CNCbl interference on total hemoglobin and hemoglobin derivatives is evaluated using the measured difference between the control sample and the spiked sample. Spectral measurements, blood measurements and delta spectral data confirmed that hemoglobin measurement accuracy is affected by the presence of OHCbl or CNCbl and that the source of interference is from errors in measurement algorithms, and not due to cobalamin induced hemoglobin changes. Among the 4 co-oximeters tested in this evaluation, GEM Premier 4000 and Rapidpoint 405 analyzer showed minimal impact for hydroxocobalamin concentrations around 0.5 g/l. Cyanocobalamin displayed similar interference effect on co-<span class="hlt">oximetry</span> measurements as OHCbl. The error detection system in the GEM Premier 4000 appropriately detected and flagged interferences on sample measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JBO....21c5006E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JBO....21c5006E"><span>Diagnostic accuracy of a mathematical model to predict apnea-hypopnea index using nighttime pulse <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ebben, Matthew R.; Krieger, Ana C.</p> <p>2016-03-01</p> <p>The intent of this study is to develop a predictive model to convert an oxygen desaturation index (ODI) to an apnea-hypopnea index (AHI). This model will then be compared to actual AHI to determine its precision. One thousand four hundred and sixty-seven subjects given polysomnograms with concurrent pulse <span class="hlt">oximetry</span> between April 14, 2010, and February 7, 2012, were divided into model development (n=733) and verification groups (n=734) in order to develop a predictive model of AHI using ODI. Quadratic regression was used for model development. The coefficient of determination (r2) between the actual AHI and the predicted AHI (PredAHI) was 0.80 (r=0.90), which was significant at a p<0.001. The areas under the receiver operating characteristic curve ranged from 0.96 for AHI thresholds of ≥10 and ≥15/h to 0.97 for thresholds of ≥5 and ≥30/h. The algorithm described in this paper provides a convenient and accurate way to convert ODI to a predicted AHI. This tool makes it easier for clinicians to understand <span class="hlt">oximetry</span> data in the context of traditional measures of sleep apnea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16257157','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16257157"><span>In vivo study of liposomes as drug carriers to oral mucosa using EPR <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Erjavec, V; Pavlica, Z; Sentjurc, M; Petelin, M</p> <p>2006-01-03</p> <p>The purpose of this study was to select the best types of liposomes for use as drug carriers for topical treatment of oral mucosal lesions. Electron paramagnetic resonance (EPR) <span class="hlt">oximetry</span>, using the paramagnetic probe lithium phthalocyanine, was used in vivo to measure the effects of a hyperemic drug, benzyl nicotinate (BN) which was incorporated into liposomes of varying size and composition. The liposomes were made from either hydrogenated or non-hydrogenated soy lecithin and mixed with polymethyl methacrylate ointment for application. EPR <span class="hlt">oximetry</span> was used to measure the partial pressure of oxygen (pO2) in the oral mucosa before and after application of liposomes. It was found that the most pronounced changes of pO2 in oral mucosa and also the longest action of the drug occurred after the topical application of BN in multi-lamellar liposomes made from hydrogenated soy lecithin (p<0.0001). When these liposomes were applied to oral mucosa over 3 successive days it was found that pO2 increased the most on the first day, the effect gradually decreased following application on the second and third days. The duration of the resulting hyperemia was the longest on the second day (p<0.01). Among the examined carriers, multi-lamellar liposomes made from hydrogenated soy lecithin appear to be the most appropriate for local drug delivery to oral mucosa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21478073','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21478073"><span>Retinal <span class="hlt">oximetry</span> based on nonsimultaneous image acquisition using a conventional fundus camera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Sun Kwon; Kim, Dong Myung; Suh, Min Hee; Kim, Martha; Kim, Hee Chan</p> <p>2011-08-01</p> <p>To measure the retinal arteriole and venule oxygen saturation (SO(2)) using a conventional fundus camera, retinal <span class="hlt">oximetry</span> based on nonsimultaneous image acquisition was developed and evaluated. Two retinal images were sequentially acquired using a conventional fundus camera with two bandpass filters (568 nm: isobestic, 600 nm: nonisobestic wavelength), one after another, instead of a built-in green filter. The images were registered to compensate for the differences caused by eye movements during the image acquisition. Retinal SO(2) was measured using two wavelength <span class="hlt">oximetry</span>. To evaluate sensitivity of the proposed method, SO(2) in the arterioles and venules before and after inhalation of 100% O(2) were compared, respectively, in 11 healthy subjects. After inhalation of 100% O(2), SO(2) increased from 96.0 ±6.0% to 98.8% ±7.1% in the arterioles (p=0.002) and from 54.0 ±8.0% to 66.7% ±7.2% in the venules (p=0.005) (paired t-test, n=11). Reproducibility of the method was 2.6% and 5.2% in the arterioles and venules, respectively (average standard deviation of five measurements, n=11).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.616a2001C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.616a2001C"><span>Development and initial testing of a pulse <span class="hlt">oximetry</span> prototype for measuring dental pulp vitality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cerqueira, M.; Ferreira, M.; Caramelo, F.</p> <p>2015-05-01</p> <p>The guiding principle of endodontic treatment is to preserve teeth while maintaining its aesthetic and functional roles. To accomplish this goal the assessment of teeth pulp vitality is very important since it will determine the procedures that should be adopted and define the therapy strategy. Currently, the most commonly tests for determining dental pulp state are the thermal and the electrical tests, which are based on nerve response and, because of that, have a relatively high rate of false positives and false negatives cases. In this work we present a simple test to be used in the clinical setting for evaluating noninvasively the existence of blood perfusion in dental pulp. This test is based on pulse <span class="hlt">oximetry</span> principle that was devised to indirectly measure the amount of oxygen in blood. Although pulse <span class="hlt">oximetry</span> has already demonstrated its usefulness in clinical environment its usage for the determination of dental pulp vitality has been frustrated by several factors, notably the absence of a suitable sensor to the complex shape of the various coronary teeth. We developed a suitable sensor and present the first trials with promising results, regarding the ability for distinguish teeth with and without blood perfusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20006529','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20006529"><span>A paramagnetic implant containing lithium naphthalocyanine microcrystals for high-resolution biological <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meenakshisundaram, Guruguhan; Pandian, Ramasamy P; Eteshola, Edward; Lee, Stephen C; Kuppusamy, Periannan</p> <p>2010-03-01</p> <p>Lithium naphthalocyanine (LiNc) is a microcrystalline EPR <span class="hlt">oximetry</span> probe with high sensitivity to oxygen [R.P. Pandian, M. Dolgos, C. Marginean, P.M. Woodward, P.C. Hammel, P.T. Manoharan, P. Kuppusamy, Molecular packing and magnetic properties of lithium naphthalocyanine crystal: hollow channels enabling permeability and paramagnetic sensitivity to molecular oxygen J. Mater. Chem. 19 (2009) 4138-4147]. However, direct implantation of the crystals in the tissue for in vivo oxygen measurements may be hindered by concerns associated with their direct contact with the tissue/cells and loss of EPR signal due to particle migration in the tissue. In order to address these concerns, we have developed encapsulations (chips) of LiNc microcrystals in polydimethyl siloxane (PDMS), an oxygen-permeable, bioinert polymer. <span class="hlt">Oximetry</span> evaluation of the fabricated chips revealed that the oxygen sensitivity of the crystals was unaffected by encapsulation in PDMS. Chips were stable against sterilization procedures or treatment with common biological oxidoreductants. In vivo oxygen measurements established the ability of the chips to provide reliable and repeated measurements of tissue oxygenation. This study establishes PDMS-encapsulated LiNc as a potential probe for long-term and repeated measurements of tissue oxygenation. Copyright (c) 2009 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27000014','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27000014"><span>Inaccurate pulse CO-<span class="hlt">oximetry</span> of carboxyhemoglobin due to digital clubbing: case report.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Harlan, Nicole; Weaver, Lindell K; Deru, Kayla</p> <p>2016-01-01</p> <p>Newer pulse CO-oximeters provide a non-invasive and quick means of measuring oxyhemoglobin, carboxyhemoglobin and methemoglobin. Clubbing has been reported to cause inaccuracy in pulse oximeters. We present a case of inaccurate carboxy-hemoglobin measurement by pulse CO-<span class="hlt">oximetry</span> due to digital clubbing. An 18-year-old man with a history of cystic fibrosis presented after a suicide attempt by inhalation of exhaust. At the initial emergency department evaluation, his blood carboxyhemoglobin was 33%. He was intubated, placed on 100% oxygen and transferred to our facility. Upon arrival, we placed three different pulse CO-oximeters on different fingers and toes. Carboxyhemoglobin levels measured by these meters ranged from 9%-11%. A venous blood gas drawn on arrival showed a carboxyhemoglobin level of 2.3% after four hours on 100% oxygen by endotracheal tube. Thirty minutes later, we checked arterial blood gas, which revealed a COHb level of 0.9%. Again, non-invasive carboxyhemoglobin measurements read 10%. The patient was treated with hyperbaric oxygen for carbon monoxide poisoning. This case suggests that non-invasive measurements of carboxyhemoglobin should be correlated with the clinic history and with an arterial or venous blood gas <span class="hlt">oximetry</span> analysis.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997OptEn..36.1225C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997OptEn..36.1225C"><span>One-dimensional representation of light-tissue interaction for application in noninvasive <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cysewska-Sobusiak, Anna</p> <p>1997-04-01</p> <p>The transillumination window in the tissue spectrum, which extends from about 600 to about 1200 nm, is very attractive in diagnosis and therapy because the penetration of light into tissues ranges from several micrometers to several millimeters. Problems with the evaluation of red and near-IR light-tissue interaction are of great importance in the development of noninvasive blood <span class="hlt">oximetry</span>. It is shown that it is possible to use a significant 1D representation of such an interaction with a reliability acceptance in practice. The state of the art, taken into account here as the background, refers to the reported optical parameters of tissues when exposed to light of wavelengths included in the optical window considered. Against that background, using the arterial blood oxygen saturation as a measurement quantity, a reasonably complicated model of noninvasive processes occurring in a living object as a pulsatile inhomogeneous optical medium is presented. During the calculations and experiments, a novel use of the known transmission variant of the pulse <span class="hlt">oximetry</span> concept is considered. At two measuring wavelengths (i.e., 660 and 940 nm), the biophysical and optical properties of living tissues are involved in relationships that include the quantities to be directly measured with known accuracy. Finally, the results of calculations referring to the transilluminated representative object (i.e., a theoretical fingertip) are compared to the appropriate results obtained during a series of measurements performed on real human subjects using the designed measuring system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26719242','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26719242"><span>Regularity analysis of nocturnal <span class="hlt">oximetry</span> recordings to assist in the diagnosis of sleep apnoea syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marcos, J Víctor; Hornero, Roberto; Nabney, Ian T; Álvarez, Daniel; Gutiérrez-Tobal, Gonzalo C; del Campo, Félix</p> <p>2016-03-01</p> <p>The relationship between sleep apnoea-hypopnoea syndrome (SAHS) severity and the regularity of nocturnal oxygen saturation (SaO2) recordings was analysed. Three different methods were proposed to quantify regularity: approximate entropy (AEn), sample entropy (SEn) and kernel entropy (KEn). A total of 240 subjects suspected of suffering from SAHS took part in the study. They were randomly divided into a training set (96 subjects) and a test set (144 subjects) for the adjustment and assessment of the proposed methods, respectively. According to the measurements provided by AEn, SEn and KEn, higher irregularity of <span class="hlt">oximetry</span> signals is associated with SAHS-positive patients. Receiver operating characteristic (ROC) and Pearson correlation analyses showed that KEn was the most reliable predictor of SAHS. It provided an area under the ROC curve of 0.91 in two-class classification of subjects as SAHS-negative or SAHS-positive. Moreover, KEn measurements from <span class="hlt">oximetry</span> data exhibited a linear dependence on the apnoea-hypopnoea index, as shown by a correlation coefficient of 0.87. Therefore, these measurements could be used for the development of simplified diagnostic techniques in order to reduce the demand for polysomnographies. Furthermore, KEn represents a convincing alternative to AEn and SEn for the diagnostic analysis of noisy biomedical signals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21137662','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21137662"><span>Evaluation of oxygen saturation by pulse-<span class="hlt">oximetry</span> in mouth breathing patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niaki, Esfandiar Akhavan; Chalipa, Javad; Taghipoor, Elahe</p> <p>2010-01-01</p> <p>Mouth breathing might not always result in hypoxia, but can contribute to it. The aim of the present study was to determine the effect of mouth breathing on hypoxia. Based on a pilot study, 323 patients with mouth breathing were selected. Assessment of mouth breathing was based on clinical examination and questionnaires filled out by patients and their companions. The patients were also examined for further oral findings that could be attributable to mouth breathing. Oxygen saturation of each case was measured by means of a pulse <span class="hlt">oximetry</span> device. The level of 95% saturation was set as the limit, under which the patient was considered hypoxemic. Acquired data was analyzed for descriptive data and frequency and also by means of the Chi-square and Spearman's correlation coefficient tests. 34.6% of the cases had normal O2 saturation. 65.4% of cases were hypoxemic (saturation level was below 95% in 42.8% and 95% in 22.6%). Most of the mouth breathing patients were male who were also more hypoxemic. A weak inverse relationship existed between the age of the patients and Oxygen saturation. Deep palatal vaults (29.4%) and gingival hyperplasia (29.2%) were the most frequent intraoral findings. Concerning the effects of hypoxia on body systems, the use of pulse <span class="hlt">oximetry</span> in suspected mouth breathing patients could be recommended in routine oral and dental examinations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26732768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26732768"><span>Assessment of Noninvasive Regional Brain <span class="hlt">Oximetry</span> in Posterior Reversible Encephalopathy Syndrome and Reversible Cerebral Vasoconstriction Syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chung, David Y; Claassen, Jan; Agarwal, Sachin; Schmidt, J Michael; Mayer, Stephan A</p> <p>2016-07-01</p> <p>Posterior reversible encephalopathy syndrome (PRES) leads to small- and large-vessel circulatory dysfunction. While aggressive lowering of elevated blood pressure is the usual treatment for PRES, excessive blood pressure reduction may lead to ischemia or infarction, particularly when PRES is accompanied by reversible cerebral vasoconstriction syndrome (RCVS). Regional cerebral <span class="hlt">oximetry</span> using near-infrared spectroscopy is a noninvasive modality that is commonly used intraoperatively and in intensive care settings to monitor regional cerebral oxygenation (rSO2) and may be useful in guiding treatment in select cases of PRES and RCVS. We report a case of a patient with PRES complicated by infarction and RCVS where the optimal blood pressure management was unclear. A decision was made to decrease blood pressure which resulted in an improved neurological examination and increase in rSO2 from 40% to 55% in at-risk brain. Infarcted brain as determined by diffusion-weighted magnetic resonance imaging and computed tomography perfusion imaging showed no change in rSO2 during the same time period. Furthermore, there was a qualitative change in the rSO2-mean arterial pressure (MAP) relationship, suggesting an alteration in cerebrovascular autoregulation as a result of lowering blood pressure. Regional cerebral <span class="hlt">oximetry</span> can provide valuable diagnostic feedback in complicated cases of PRES and RCVS. © The Author(s) 2016.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM14A..08D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM14A..08D"><span>Effect of Spatial Density <span class="hlt">Variation</span> and O+ Concentration on the Growth and Evolution of Electromagnetic Ion Cyclotron <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, R. E.; Jordanova, V.; Fraser, B. J.</p> <p>2014-12-01</p> <p>We simulate electromagnetic ion cyclotron (EMIC) <span class="hlt">waves</span>, which were observed during June 9, 2001 by Geostationary Operational Environmental Satellite (GOES) spacecraft. First we use a ring current simulation with a plasmasphere model to model the particle populations that give rise to the instability. Then, using two different models for the cold ion composition, we do a full scale hybrid code simulation in dipole coordinates of the EMIC <span class="hlt">waves</span> on a meridional plane at MLT = 18 and at 1900 UT within a range of L shell from L = 4.9 to 6.7. While an exact comparison between observed and simulated spectra is not possible here, we do find significant similarities between the two, at least in certain regions. We simulate the EMIC <span class="hlt">wave</span> growth and evolution within three regions, the plasmasphere (or plasmaspheric plume), the plasmapause, and the low density plasmatrough outside the plasmapause. We find that the plasmapause is not a preferred region for EMIC <span class="hlt">wave</span> growth, though <span class="hlt">waves</span> can grow in that region. There is a preference for EMIC <span class="hlt">waves</span> to be driven in the He+ band (frequencies between the O+ and He+ gyrofrequencies) within the plasmasphere, although they can also grow in the plasmatrough. If present, H+ band <span class="hlt">waves</span> are more likely to grow in the plasmatrough. This fact, plus L dependence of the frequency and possible time evolution toward lower frequency <span class="hlt">waves</span> can be explained by a simple model. Large O+ concentration limits the frequency range of or even totally quenches EMIC <span class="hlt">waves</span>. This is more likely to occur in the plasmatrough at solar maximum. Such large O+ concentration significantly affects the H+ cutoff frequency, and hence the width in frequency of the stop band above the He+ gyrofrequency. EMIC <span class="hlt">wave</span> surfaces predicted by cold plasma theory may not be valid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1193682-effect-spatial-density-variation-concentration-growth-evolution-electromagnetic-ion-cyclotron-waves','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1193682-effect-spatial-density-variation-concentration-growth-evolution-electromagnetic-ion-cyclotron-waves"><span>Effect of spatial density <span class="hlt">variation</span> and O+ concentration on the growth and evolution of electromagnetic ion cyclotron <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Denton, R. E.; Jordanova, V. K.; Fraser, B. J.</p> <p>2014-10-01</p> <p>We simulate electromagnetic ion cyclotron (EMIC) <span class="hlt">wave</span> growth and evolution within three regions, the plasmasphere (or plasmaspheric plume), the plasmapause, and the low-density plasmatrough outside the plasmapause. First, we use a ring current simulation with a plasmasphere model to model the particle populations that give rise to the instability for conditions observed on 9 June 2001. Then, using two different models for the cold ion composition, we do a full scale hybrid code simulation in dipole coordinates of the EMIC <span class="hlt">waves</span> on a meridional plane at MLT = 18 and at 1900 UT within a range of L shell frommore » L = 4.9 to 6.7. EMIC <span class="hlt">waves</span> were observed during June 9, 2001 by Geostationary Operational Environmental Satellite (GOES) spacecraft. While an exact comparison between observed and simulated spectra is not possible here, we do find significant similarities between the two, at least at one location within the region of largest <span class="hlt">wave</span> growth. We find that the plasmapause is not a preferred region for EMIC <span class="hlt">wave</span> growth, though <span class="hlt">waves</span> can grow in that region. The density gradient within the plasmapause does, however, affect the orientation of <span class="hlt">wave</span> fronts and <span class="hlt">wave</span> vector both within the plasmapause and in adjacent regions. There is a preference for EMIC <span class="hlt">waves</span> to be driven in the He+ band (frequencies between the O+ and He+ gyrofrequencies) within the plasmasphere, although they can also grow in the plasmatrough. If present, H+ band <span class="hlt">waves</span> are more likely to grow in the plasmatrough. This fact, plus L dependence of the frequency and possible time evolution toward lower frequency <span class="hlt">waves</span>, can be explained by a simple model. Large O+ concentration limits the frequency range of or even totally quenches EMIC <span class="hlt">waves</span>. This is more likely to occur in the plasmatrough at solar maximum. Such large O+ concentration significantly affects the H+ cutoff frequency and hence the width in frequency of the stop band above the He+ gyrofrequency. EMIC <span class="hlt">wave</span> surfaces predicted by cold</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1193682','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1193682"><span>Effect of spatial density <span class="hlt">variation</span> and O+ concentration on the growth and evolution of electromagnetic ion cyclotron <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Denton, R. E.; Jordanova, V. K.; Fraser, B. J.</p> <p>2014-10-01</p> <p>We simulate electromagnetic ion cyclotron (EMIC) <span class="hlt">wave</span> growth and evolution within three regions, the plasmasphere (or plasmaspheric plume), the plasmapause, and the low-density plasmatrough outside the plasmapause. First, we use a ring current simulation with a plasmasphere model to model the particle populations that give rise to the instability for conditions observed on 9 June 2001. Then, using two different models for the cold ion composition, we do a full scale hybrid code simulation in dipole coordinates of the EMIC <span class="hlt">waves</span> on a meridional plane at MLT = 18 and at 1900 UT within a range of L shell from L = 4.9 to 6.7. EMIC <span class="hlt">waves</span> were observed during June 9, 2001 by Geostationary Operational Environmental Satellite (GOES) spacecraft. While an exact comparison between observed and simulated spectra is not possible here, we do find significant similarities between the two, at least at one location within the region of largest <span class="hlt">wave</span> growth. We find that the plasmapause is not a preferred region for EMIC <span class="hlt">wave</span> growth, though <span class="hlt">waves</span> can grow in that region. The density gradient within the plasmapause does, however, affect the orientation of <span class="hlt">wave</span> fronts and <span class="hlt">wave</span> vector both within the plasmapause and in adjacent regions. There is a preference for EMIC <span class="hlt">waves</span> to be driven in the He+ band (frequencies between the O+ and He+ gyrofrequencies) within the plasmasphere, although they can also grow in the plasmatrough. If present, H+ band <span class="hlt">waves</span> are more likely to grow in the plasmatrough. This fact, plus L dependence of the frequency and possible time evolution toward lower frequency <span class="hlt">waves</span>, can be explained by a simple model. Large O+ concentration limits the frequency range of or even totally quenches EMIC <span class="hlt">waves</span>. This is more likely to occur in the plasmatrough at solar maximum. Such large O+ concentration significantly affects the H+ cutoff frequency and hence the width in frequency of the stop band above the He+ gyrofrequency. EMIC <span class="hlt">wave</span> surfaces predicted by cold plasma theory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900018887','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018887"><span>The 27-day versus 13.5-day <span class="hlt">variations</span> in the solar Lyman-alpha radiation and the radio <span class="hlt">wave</span> absorption in the lower ionosphere over Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delamorena, B. A.; Lastovicka, Jan; Rapoport, Z. TS.; Alberca, L.</p> <p>1989-01-01</p> <p>In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio <span class="hlt">wave</span> absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha <span class="hlt">variation</span> on time scale day-month is the solar rotation <span class="hlt">variation</span> (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by <span class="hlt">variations</span> of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PMB....62.1149W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PMB....62.1149W"><span>An analysis of intrinsic <span class="hlt">variations</span> of low-frequency shear <span class="hlt">wave</span> speed in a stochastic tissue model: the first application for staging liver fibrosis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yu; Wang, Min; Jiang, Jingfeng</p> <p>2017-02-01</p> <p>Shear <span class="hlt">wave</span> elastography is increasingly being used to non-invasively stage liver fibrosis by measuring shear <span class="hlt">wave</span> speed (SWS). This study quantitatively investigates intrinsic <span class="hlt">variations</span> among SWS measurements obtained from heterogeneous media such as fibrotic livers. More specifically, it aims to demonstrate that intrinsic <span class="hlt">variations</span> in SWS measurements, in general, follow a non-Gaussian distribution and are related to the heterogeneous nature of the medium being measured. Using the principle of maximum entropy (ME), our primary objective is to derive a probability density function (PDF) of the SWS distribution in conjunction with a lossless stochastic tissue model. Our secondary objective is to evaluate the performance of the proposed PDF using Monte Carlo (MC)-simulated shear <span class="hlt">wave</span> (SW) data against three other commonly used PDFs. Based on statistical evaluation criteria, initial results showed that the derived PDF fits better to MC-simulated SWS data than the other three PDFs. It was also found that SW fronts stabilized after a short (compared with the SW wavelength) travel distance in lossless media. Furthermore, in lossless media, the distance required to stabilize the SW propagation was not correlated to the SW wavelength at the low frequencies investigated (i.e. 50, 100 and 150 Hz). Examination of the MC simulation data suggests that elastic (shear) <span class="hlt">wave</span> scattering became more pronounced when the volume fraction of hard inclusions increased from 10 to 30%. In conclusion, using the principle of ME, we theoretically demonstrated for the first time that SWS measurements in this model follow a non-Gaussian distribution. Preliminary data indicated that the proposed PDF can quantitatively represent intrinsic <span class="hlt">variations</span> in SWS measurements simulated using a two-phase random medium model. The advantages of the proposed PDF are its physically meaningful parameters and solid theoretical basis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.204.1789B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.204.1789B"><span>Evidence for MAC <span class="hlt">waves</span> at the top of Earth's core and implications for <span class="hlt">variations</span> in length of day</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buffett, Bruce; Knezek, Nicholas; Holme, Richard</p> <p>2016-03-01</p> <p>Earth's liquid core hosts a diverse set of <span class="hlt">waves</span> with periods ranging from days to thousands of years. One class of <span class="hlt">waves</span> with periods of several decades is known to arise from an interplay between magnetic, Archimedes and Coriolis forces. These so-called MAC <span class="hlt">waves</span> are thought to be relevant for interpreting historical fluctuations in the geomagnetic field. In this study, we show that MAC <span class="hlt">waves</span> provide a good description of time-dependent zonal flow at the top of the core. The same collection of <span class="hlt">waves</span> also offers a simple explanation for observed fluctuations in the dipole field. Both of these predictions require a stratified layer at the top of the core with a thickness of 130-140 km and a buoyancy frequency comparable to Earth's rotation rate. We extend these predictions to include changes in the length of day (LOD) and find that MAC <span class="hlt">waves</span> can account for about half of the observed fluctuation at decadal periods. Larger fluctuations are possible when electromagnetic stresses couple MAC <span class="hlt">waves</span> to flow in the interior of the core. In fact, an idealized model for the coupled motion overestimates the LOD fluctuations, probably reflecting limitations in this idealized model. Our results offer support for stable stratification at the top of the core and suggest a common origin for decadal fluctuations in the geomagnetic field and the LOD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.waveworkshop.org/10thWaves/ProgramFrameset.htm','USGSPUBS'); return false;" href="http://www.waveworkshop.org/10thWaves/ProgramFrameset.htm"><span>Coupling alongshore <span class="hlt">variations</span> in <span class="hlt">wave</span> energy to beach morphologic change using the SWAN <span class="hlt">wave</span> model at Ocean Beach, San Francisco, CA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Eshleman, Jodi L.; Barnard, Patrick L.; Erikson, Li H.; Hanes, Daniel M.</p> <p>2007-01-01</p> <p>Coastal managers have faced increasing pressure to manage their resources wisely over the last century as a result of heightened development and changing environmental forcing. It is crucial to understand seasonal changes in beach volume and shape in order to identify areas vulnerable to accelerated erosion. Shepard (1950) was among the first to quantify seasonal beach cycles. Sonu and Van Beek (1971) and Wright et al. (1985) described commonly occurring beach states. Most studies utilize widest spaced 2-D cross shore profiles or shorelines extracted from aerial photographs (e.g. Winant et al. 1975; Aubrey, 1979, Aubrey and Ross, 1985; Larson and Kraus, 1994; Jimenez et al., 1977; Lacey and Peck, 1998; Guillen et al., 1999; Norcorss et al., 2002) to analyzed systematic changes in beach evolution. But with the exception of established field stations, such as Duck, NC (Birkemeier and Mason, 1984), ans Hazaki Oceanographical Research Station (HORS) in Japan (Katoh, 1997), there are very few beach change data sets with high temporal and spatial resolutions (e.g. Dail et al., 2000; Ruggiero et al., 2005; Yates et al., in press). Comprehensive sets of nearshore morphological data and local in situ measurements outside of these field stations are very rare and virtually non-existent high-energy coasts. Studied that have attempted to relate <span class="hlt">wave</span> statistics to beach morphology change require some knowledge of the nearshore <span class="hlt">wave</span> climate, and have had limited success using offshore measurement (Sonu and Van Beek, 1971; Dail et al., 2000). The primary objective of this study is to qualitatively compare spatially variable nearshore <span class="hlt">wave</span> predictions to beach change measurements in order to understand the processes responsible for a persistent erosion 'hotspot' at Ocean Beach, San Francisco, CA. Local <span class="hlt">wave</span> measurements are used to calibrate and validate a <span class="hlt">wave</span> model that provides nearshore <span class="hlt">wave</span> prediction along the beach. The model is run for thousands of binned offshore <span class="hlt">wave</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25641083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25641083"><span>Pulse <span class="hlt">oximetry</span> screening and prenatal diagnosis play complementary roles in reducing risks in simple transposition of the great arteries.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bartos, Marie; Lannering, Katarina; Mellander, Mats</p> <p>2015-06-01</p> <p>This study quantified the contribution of pulse <span class="hlt">oximetry</span> screening to an early diagnosis of simple transposition. We also estimated the proportion of neonates with this life-threatening cardiac defect who could benefit from prenatal diagnosis, even when pulse <span class="hlt">oximetry</span> screening had been implemented. This population-based, retrospective, cohort study of cases born from 2003 to 2013 used data from surgical files, the Swedish Causes of Death Registry and the National Forensic Medicine database. The main outcome measures were early postnatal circulatory instability, pre-operative death, neurological morbidity and risk of discharge before diagnosis. We identified 89 cases, including three diagnosed prenatally. Hospitals using pulse <span class="hlt">oximetry</span> screening diagnosed all 31 neonates before discharge, including seven as a result of screening, but 10 of 55 infants in the nonscreening hospitals were discharged undiagnosed (p = 0.017). Prenatal diagnosis could have decreased the risk of early circulatory instability, pre-operative death or neurological morbidity in 12 of the 72 infants born in referring hospitals (17%). There was one pre-operative death and no postoperative deaths at a mean follow-up of 4.7 years. Pulse <span class="hlt">oximetry</span> screening minimised the risk of discharging infants with transposition, but prenatal diagnosis would have been necessary to avoid early circulatory instability in 17% of cases. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26322819','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26322819"><span>Use of Intermittent vs Continuous Pulse <span class="hlt">Oximetry</span> for Nonhypoxemic Infants and Young Children Hospitalized for Bronchiolitis: A Randomized Clinical Trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCulloh, Russell; Koster, Michael; Ralston, Shawn; Johnson, Matthew; Hill, Vanessa; Koehn, Kristin; Weddle, Gina; Alverson, Brian</p> <p>2015-10-01</p> <p>Clinical practice guidelines for managing infants and children hospitalized for bronchiolitis recommend only obtaining intermittent or "spot check" pulse <span class="hlt">oximetry</span> readings for those who show clinical improvement. The effect of such monitoring is currently unknown. To determine the effect of intermittent vs continuous pulse <span class="hlt">oximetry</span> monitoring on hospital length of stay among nonhypoxemic infants and young children hospitalized for bronchiolitis. Randomized, parallel-group, superiority clinical trial of otherwise healthy infants and children 2 years of age or younger hospitalized for bronchiolitis during the period from 2009 to 2014 at 1 of 4 children's hospitals in the United States. Parents or guardians were blinded to allocation assignment until informed consent was obtained; study personnel and outcome assessors were not. Patients were randomly assigned to undergo continuous or intermittent pulse <span class="hlt">oximetry</span> monitoring (ie, pulse <span class="hlt">oximetry</span> measurements were obtained along with a scheduled check of vital signs or for clinical suspicion of deterioration) during hospitalization when oxygen saturation levels were 90% or higher. Length of hospital stay was the primary outcome. Secondary outcome measures included duration of supplemental oxygen use and rate of escalation of care (defined as transfer to an intensive care unit). A total of 449 infants and young children were screened for inclusion; 288 infants and young children were excluded, resulting in 161 patients who were enrolled in the study (80 patients underwent continuous monitoring, and 81 patients intermittent). The mean length of stay did not differ based on pulse <span class="hlt">oximetry</span> monitoring strategy (48.9 hours [95% CI, 41.3-56.5 hours] for continuous monitoring vs 46.2 hours [95% CI, 39.1-53.3 hours] for intermittent monitoring; P = .77). The rates of escalation of care and duration of supplemental oxygen use did not differ between groups. Intermittent pulse <span class="hlt">oximetry</span> monitoring of nonhypoxemic patients with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24768155','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24768155"><span>Pulse <span class="hlt">oximetry</span> with clinical assessment to screen for congenital heart disease in neonates in China: a prospective study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Qu-ming; Ma, Xiao-jing; Ge, Xiao-ling; Liu, Fang; Yan, Wei-li; Wu, Lin; Ye, Ming; Liang, Xue-cun; Zhang, Jing; Gao, Yan; Jia, Bing; Huang, Guo-ying</p> <p>2014-08-30</p> <p>Several pioneering studies have provided evidence for the introduction of universal pulse <span class="hlt">oximetry</span> screening for critical congenital heart disease. However, whether the benefits of screening reported in studies from high-income countries would translate with similar success to low-income countries is unknown. We assessed the feasibility and reliability of pulse <span class="hlt">oximetry</span> plus clinical assessment for detection of major congenital heart disease, especially critical congenital heart disease, in China. We did a pilot study at three hospitals in Shanghai to assess the accuracy of pulse <span class="hlt">oximetry</span> plus clinical assessment for detection of congenital heart disease. We made a data collection plan before recruitment. We then undertook a large, prospective, and multicentre screening study in which we screened all consecutive newborn babies (aged 6-72 h) born at 18 hospitals in China between Aug 1, 2011, and Nov 30, 2012. Newborn babies with positive screen results (either an abnormal pulse <span class="hlt">oximetry</span> or abnormal clinical assessment) were referred for echocardiography within 24 h of screening. We identified false-negative results by clinical follow-up and parents' feedback. We calculated sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios for pulse <span class="hlt">oximetry</span> alone, and in combination with clinical assessment, for detection of major and critical congenital heart disease. In the pilot study, 6785 consecutive newborn babies were screened; 46 of 49 (94%) cases of asymptomatic major congenital heart disease and eight of eight (100%) cases of asymptomatic critical disease were detected by pulse <span class="hlt">oximetry</span> and clinical assessment. In the prospective multicentre study, we screened 122,738 consecutive newborn babies (120,707 asymptomatic and 2031 symptomatic), and detected congenital heart disease in 1071 (157 critical and 330 major). In asymptomatic newborn babies, the sensitivity of pulse <span class="hlt">oximetry</span> plus clinical assessment was 93·2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20974876','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20974876"><span>Nonlinear dust acoustic <span class="hlt">waves</span> in a nonuniform magnetized complex plasma with nonthermal ions and dust charge <span class="hlt">variation</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>El-Taibany, W. F.; Wadati, Miki; Sabry, R.</p> <p>2007-03-15</p> <p>Propagations of nonlinear dust acoustic (DA) solitary <span class="hlt">waves</span> and shock <span class="hlt">waves</span> in a nonuniform magnetized dusty plasma are investigated. The incorporation of the combined effects of nonthermally distributed ions, nonadiabatic dust charge fluctuation, and the inhomogeneity caused by nonuniform equilibrium values of particle density, charging variable, and particle potential on the <span class="hlt">waves</span> leads to a significant modification to the nature of nonlinear DA solitary <span class="hlt">waves</span>. The nonlinear <span class="hlt">wave</span> evolution is governed by a modified Zakhavov-Kusnetsov-Burgers (MZKB) equation, whose coefficients are space dependent. Using a generalized expansion method, new solutions for the MZKB equation are obtained. The form of solutions consists of two parts; one of them is the amplitude factor and the other is a superposition of bell-shaped and kink-type shock <span class="hlt">waves</span>. New solutions are classified into three categories. A type of the solution is determined depending on the nonthermal parameter. Findings in this investigation should be useful for understanding the ion acceleration mechanisms close to the Moon and also enhancing our knowledge on pickup ions around unmagnetized bodies, such as comets, Mars, and Venus, including medium inhomogeneities with nonadiabatic dust charging processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Geomo.280...76H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.280...76H"><span>The effect of wind <span class="hlt">waves</span> on spring-neap <span class="hlt">variations</span> in sediment transport in two meso-tidal estuarine basins with contrasting fetch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hunt, Stephen; Bryan, Karin R.; Mullarney, Julia C.</p> <p>2017-03-01</p> <p>Higher-energy episodic wind-<span class="hlt">waves</span> can substantially modify estuarine morphology over short timescales which are superimposed on lower-energy but long-term tidal asymmetry effects. Theoretically, wind <span class="hlt">waves</span> and tidal currents change the morphology through their combined influence on the asymmetry between bed shear stress, τmax, on the flood and ebb tide, although the relative contribution of such wind-<span class="hlt">wave</span> events in shaping the long-term morphological evolution in real estuaries is not well known. If the rising tide reaches sufficiently high water depths, τmax decreases as water depth increases because of the depth attenuation of <span class="hlt">wave</span> orbital velocities. However, this effect is opposed by the increase in τmax associated with the longer fetch occurring at high tide, which allows the generation of larger <span class="hlt">waves</span>. Additionally, these effects are superimposed on the spring-neap <span class="hlt">variations</span> in current associated with changes to tidal range. By comparing two mesotidal basins in the same dendritic estuary, one with a large fetch aligned with the prevailing wind direction and one with only a small fetch, we show that for a sufficiently large fetch even the small and frequently occurring wind events are able to create <span class="hlt">waves</span> that are capable of changing the morphology ('morphologically significant'). Conversely, in the basin with reduced fetch, these <span class="hlt">waves</span> are generated less frequently and therefore are of reduced morphological significance. Here, we find that although tidal current should be stronger during spring tides and alter morphology more, on average the reduced fetch and increased water depth during spring tides mean that the basin-averaged intertidal τmax is similar during both spring and neap tides. Moreover, in the presence of wind <span class="hlt">waves</span>, the duration of slack water is reduced during neap tides relative to spring tides, resulting in a reduced chance for accretion during neap tides. Finally, τmax is lower in the subtidal channels during neaps than springs but of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12735411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12735411"><span>Evaluation of non-reassuring fetal heart rate patterns with fetal pulse <span class="hlt">oximetry</span> combined with vibratory acoustic stimulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Salamalekis, E; Vitoratos, N; Loghis, C; Kassanos, D; Salloum, I; Batalias, L; Creatsas, G</p> <p>2003-02-01</p> <p>To determine the value of fetal pulse <span class="hlt">oximetry</span> and vibratory acoustic stimulation in the presence of non-reassuring fetal heart rate patterns during labor. Prospective study in women monitored by cardiotocography and fetal pulse <span class="hlt">oximetry</span> during labor. During a period of 18 months, 907 consecutive parturients in labor were monitored by cardiotocography. Out of these women, 63 were selected on the basis of a non-reassuring fetal heart rate tracing during the first stage of labor. In these cases, fetal pulse <span class="hlt">oximetry</span> was applied. Vibratory acoustic stimulation was applied in fetuses without spontaneous reactivity in order to evaluate the fetal status. Our cases were classified into three groups, according to the lower fetal oxygen saturation levels, from the time of <span class="hlt">oximetry</span> application until delivery. Group A consisted of 29 cases where fetal oxygen saturation levels were > or = 41%, group B (20 cases) with fetal oxygen saturation of 31-40% and group C (14 cases) with levels of < 30%. Spontaneous reactivity was observed in 15 fetuses of group A and seven of group B, while no case of reactivity was noted in group C. Vibratory acoustic-induced reactivity was associated with low fetal oxygen saturation levels. The mean umbilical artery pH levels were 7.29 +/- 0.051 in group A, 7.21 +/- 0.057 in group B and 7.04 +/- 0.05 in group C. Fetal pulse <span class="hlt">oximetry</span> should be indicated not only in fetuses without any reactivity but also in those with induced reactivity, after the application of vibratory acoustic stimulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24472198','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24472198"><span>Using bispectral index and cerebral <span class="hlt">oximetry</span> to guide hemodynamic therapy in high-risk surgical patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bidd, Heena; Tan, Audrey; Green, David</p> <p>2013-05-19</p> <p>High-risk surgery represents 12.5% of cases but contributes 80% of deaths in the elderly population. Reduction in morbidity and mortality by the use of intervention strategies could result in thousands of lives being saved and savings of up to £400m per annum in the UK. This has resulted in the drive towards goal-directed therapy and intraoperative flow optimization of high-risk surgical patients being advocated by authorities such as the National Institute of Health and Care Excellence and the Association of Anaesthetists of Great Britain and Ireland.Conventional intraoperative monitoring gives little insight into the profound physiological changes occurring as a result of anesthesia and surgery. The build-up of an oxygen debt is associated with a poor outcome and strategies have been developed in the postoperative period to improve outcomes by repayment of this debt. New monitoring technologies such as minimally invasive cardiac output, depth of anesthesia and cerebral <span class="hlt">oximetry</span> can minimize oxygen debt build-up. This has the potential to reduce complications and lessen the need for postoperative optimization in high-dependency areas.Flow monitoring has thus emerged as essential during intraoperative monitoring in high-risk surgery. However, evidence suggests that current optimization strategies of deliberately increasing flow to meet predefined targets may not reduce mortality.Could the addition of depth of anesthesia and cerebral and tissue <span class="hlt">oximetry</span> monitoring produce a further improvement in outcomes?Retrospective studies indicate a combination of excessive depth of anesthesia hypotension and low anesthesia requirement results in increased mortality and length of hospital stay.Near infrared technology allows assessment and maintenance of cerebral and tissue oxygenation, a strategy, which has been associated with improved outcomes. The suggestion that the brain is an index organ for tissue oxygenation, especially in the elderly, indicates a role for this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Ge%26Ae..57..451K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Ge%26Ae..57..451K"><span>Quasi-<span class="hlt">wave</span> <span class="hlt">variations</span> in foEs during stratospheric warmings of 2008-2010 according to data from Kaliningrad ionospheric station</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koren'kov, Yu. N.; Koren'kova, N. A.; Bessarab, F. S.; Lechshenko, V. S.</p> <p>2017-07-01</p> <p>The results of analysis of <span class="hlt">variations</span> in the sporadic layer critical frequency ( foEs) for winter periods of 2008-2010 in which sudden stratospheric warmings were observed are presented in the paper. The data were obtained at Kaliningrad ionospheric station (54.6° N, 20° E) by a Parus digital ionosonde under the usual sounding regime with an interval of 15 min. Daily mean values of foEs were used for the analysis. Solar and geomagnetic activity remained low during the periods under study, making it possible to relate the quasiwave time <span class="hlt">variations</span> in foEs to the parameters of stratospheric warmings. The results of spectral analysis performed on the basis of continuous wavelet transform showed that, during all warmings occurring in 2008-2010, time <span class="hlt">variations</span> in foEs show the presence of <span class="hlt">wave</span> processes with a period of an order of 5 days and longer ones with a period of 10—11 days. These periods coincide with characteristic periods of planetary <span class="hlt">waves</span> observed in the atmosphere during sudden stratospheric warnings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.thoracic.org/patients/patient-resources/resources/pulse-oximetry.pdf','NIH-MEDLINEPLUS'); return false;" href="http://www.thoracic.org/patients/patient-resources/resources/pulse-oximetry.pdf"><span>Pulse <span class="hlt">Oximetry</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... www.thoracic.org amount of gases (oxygen and carbon dioxide) that are in your blood. To get an ... Also, a pulse oximeter does not measure your carbon dioxide level. How accurate is the pulse oximeter? The ...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SedG..279...23V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SedG..279...23V"><span>Recognition of <span class="hlt">wave</span>-dominated, tide-influenced shoreline systems in the rock record: <span class="hlt">Variations</span> from a microtidal shoreline model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vakarelov, Boyan K.; Ainsworth, R. Bruce; MacEachern, James A.</p> <p>2012-11-01</p> <p>Existing <span class="hlt">wave</span>-dominated facies models are based on microtidal coastlines and do not adequately address <span class="hlt">wave</span>-dominated environments influenced by significant tidal ranges. Observations from modern environments show that such systems are abundant along tide-influenced shorelines facing wide shelves and large embayments, such as much of the northern Australia coast; yet equivalent deposits have been rarely recognized from the ancient record. Geomorphological literature shows that tidal influence on <span class="hlt">wave</span>-dominated shorelines has the effect of shifting the shoaling, breaking, and swash <span class="hlt">wave</span> zones up and down the beach profile; when the tidal range is appreciable, sedimentation is affected significantly. Many macrotidal, <span class="hlt">wave</span>-dominated systems (tidal range > 4 m), for example, are non-barred and are characterized by poor development of dune-scale bedforms in the subtidal zone and along the beach profile. Other systems do develop cross stratification, but this occurs in the intertidal zone rather than the subtidal zone as is implied in existing <span class="hlt">wave</span>-dominated facies models. The association of many <span class="hlt">wave</span>-dominated, tide-influenced environments with shallow shelves also suggests that major storms may be capable of reworking sediment significant distances from the shoreline. We present an ancient example of a <span class="hlt">wave</span>-dominated, tide-influenced, fluvial-affected system (Wtf) from the Campanian Bearpaw to Horseshoe Canyon Formation transition near Drumheller, Alberta, Canada, which has been described in closely spaced outcrop exposures and core. <span class="hlt">Wave</span> domination in the coarsening-upward interval is unambiguous and is represented by abundance of micro-hummocky cross stratification and other storm beds in the mudstone-dominated portions, a well-defined swaley cross stratified sandstone interval, and an up to four meter thick, horizontal planar stratified interval interpreted to have been formed by swash <span class="hlt">waves</span>. Tide influence is suggested by common double carbonaceous and mud drapes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25014964','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25014964"><span>Adaptive pulse width control and sampling for low power pulse <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gubbi, Sagar Venkatesh; Amrutur, Bharadwaj</p> <p>2015-04-01</p> <p>Remote sensing of physiological parameters could be a cost effective approach to improving health care, and low-power sensors are essential for remote sensing because these sensors are often energy constrained. This paper presents a power optimized photoplethysmographic sensor interface to sense arterial oxygen saturation, a technique to dynamically trade off SNR for power during sensor operation, and a simple algorithm to choose when to acquire samples in photoplethysmography. A prototype of the proposed pulse oximeter built using commercial-off-the-shelf (COTS) components is tested on 10 adults. The dynamic adaptation techniques described reduce power consumption considerably compared to our reference implementation, and our approach is competitive to state-of-the-art implementations. The techniques presented in this paper may be applied to low-power sensor interface designs where acquiring samples is expensive in terms of power as epitomized by pulse <span class="hlt">oximetry</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9009058','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9009058"><span>Catalase against met-Hb excess during <span class="hlt">oximetries</span> of dilute Hb-A samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ricco, G; David, O; Lanza, C; Perfetto, F; Rabino-Massa, E</p> <p>1996-01-01</p> <p>Functional parameters of diluted Hb-A have been determined before and after addition of catalase and disodium-EDTA to the samples. There are no important differences between the results drawn from catalase added samples and catalase free ones, except for the fact the met-Hb level at pH 7.8 is significantly lower in the samples containing catalase. On the contrary, catalase is almost ineffective against met-Hb at pH 6.8, whereas its activity at pH 7.3 is rather modest. Another limitation is that catalase remains active against met-Hb for not more than 15-20 minutes after addition to the sample, which is just the time necessary for one complete (manual) <span class="hlt">oximetry</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9309658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9309658"><span>Diagnosis of defects in oxidative muscle metabolism by non-invasive tissue <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bank, W; Chance, B</p> <p>1997-09-01</p> <p>The dynamics of oxygen delivery and utilization are examined in a variety of mitochondrial disorders during rest, exercise and post exercise. We used a non-invasive optical technique to measure the oxygen consumption in the exercising limb in normal subjects and 5 patients with cytochrome c oxidase deficiency. We also examined 6 patients with MELAS and MERRF syndrome. We measured near-infrared spectra of hemoglobin in the gastrocnemius muscle during treadmill exercise. Normal subjects demonstrated a sustained deoxygenation during exercise, indicating an efficient utilization of delivered oxygen. Patients with cytochrome c oxidase deficiency demonstrated consistent oxygenation during exercise indicating an under utilization of delivered oxygen. Patients with MELAS and MERRF syndrome showed similar under utilization of oxygen during exercise. Non-invasive tissue <span class="hlt">oximetry</span> during exercise demonstrates specific abnormalities in a variety of mitochondrial disorders, indicating abnormal oxygen utilization, and will be a useful addition to the clinical investigation of such disorders.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JMMM..233..131M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JMMM..233..131M"><span>Lithium naphthalocyanine as a new molecular radical probe for electron paramagnetic resonance <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manivannan, Ayyakkannu; Yanagi, Hisao; Ilangovan, Govindasamy; Kuppusamy, Periannan</p> <p>2001-08-01</p> <p>A new lithium naphthalocyanine dye aggregate [Li 2Nc][LiNc] is reported as a potential electron paramagnetic resonance (EPR) <span class="hlt">oximetry</span> probe for accurate measurement of oxygen concentration in biological systems. The Li 2Nc is diamagnetic; however, the LiNc molecule has an unpaired electron and hence is paramagnetic. The aggregate shows a strong and single line EPR signal that is non-saturating at normal EPR power levels. An oxygen-dependent peak-to-peak EPR spectral width ranging from 0.51 G (at pO 2: 0 mmHg) to 26.2 G (at pO 2: 760 mmHg) has been observed. The application of this probe has been demonstrated in the measurement of arterial and venous oxygen tensions in a rat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27090652','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27090652"><span>Is Pulse <span class="hlt">Oximetry</span> Useful for Screening Neonates for Critical Congenital Heart Disease at High Altitudes?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoffman, Julien I E</p> <p>2016-06-01</p> <p>Now that pulse <span class="hlt">oximetry</span> is used widely to screen for critical congenital heart disease, it is time to consider whether this screening method is applicable to those who live at high altitudes. Consideration of basic physical principles and reports from the literature indicate that not only is the 95 % cutoff point for arterial oxygen saturation incorrect at high altitudes, but the lower saturations are accompanied by greater variability and therefore there is the possibility of a greater percentage of false-positive screening tests at high altitudes. Because of ethnic differences in response to high altitudes, normative data will have to be collected separately in different countries and perhaps for different ethnic groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18002362','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18002362"><span>Obstructive sleep apnea detection using clustering classification of nonlinear features from nocturnal <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alvarez, Daniel; Hornero, Roberto; Marcos, J Víctor; del Campo, Félix; López, Miguel</p> <p>2007-01-01</p> <p>This study is focused on the classification of patients suspected of suffering from obstructive sleep apnea (OSA) by means of cluster analysis. We assessed the diagnostic ability of three clustering algorithms: k-means, hierarchical and fuzzy c-means (FCM). Nonlinear features of blood oxygen saturation (SaO2) from nocturnal <span class="hlt">oximetry</span> were used as inputs to the clustering methods. Three nonlinear methods were used: approximate entropy (ApEn), central tendency measure (CTM) and Lempel-Ziv (LZ) complexity. A population of 74 subjects (44 OSA positive and 30 OSA negative) was studied. 90.5%, 87.8% and 86.5% accuracies were reached with k-means, hierarchical and FCM algorithms, respectively. The diagnostic accuracy values improved those obtained with each nonlinear method individually. Our results suggest that nonlinear analysis and clustering classification could provide useful information to help in the diagnosis of OSA syndrome.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OAP....28..235L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OAP....28..235L"><span>Seasonal <span class="hlt">Variations</span> of the Ionosphere Scintillations Parameters Obtained from the Long Observations of the Power Cosmic Radio Sources at the Decameter <span class="hlt">Wave</span> Range</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lytvynenko, O. A.; Panishko, S. K.</p> <p></p> <p>Observations of the four power cosmic radio sources were carried out on the radio telescope (RT) URAN-4 during 1987-1990 and 1998-2007 at the frequencies 20 and 25 MHz. Effects of ionosphere and in particular existence of intensity fluctuations on the cosmic radio sources records, or scintillations, are essential at the decameter <span class="hlt">wave</span> range. Long series of the ionosphere scintillations parameters such as indices, periods and spectrum slopes were obtained after observation data proceeding. Behavior of the seasonal <span class="hlt">variations</span> was investigated on this data. Obtained dependencies were compared with the indices of the solar and geomagnetic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989JGR....9415415F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989JGR....9415415F"><span>The <span class="hlt">variation</span> with T(e) and T(i) of the velocity of unstable ionospheric two-stream <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farley, Donald; Providakes, Jason</p> <p>1989-11-01</p> <p>In order to test the validity of the existing expressions for the ion-acoustic velocity, simultaneous measurements were made of the electron and ion temperatures together with full spectral measurements of the phase velocity of type 4 <span class="hlt">waves</span> in the auroral zone. Details of the European Incoherent Scatter experiment using the Cornell University Portable Radar Interferometer are described, and a linear theory is developed for two-stream <span class="hlt">waves</span>, with a fluid model used for the electrons and a kinetic model for the ions. The linear theory is found to be in satisfactory agreeement with the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4679295','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4679295"><span>Application of Electron Paramagnetic Resonance (EPR) <span class="hlt">Oximetry</span> to Monitor Oxygen in Wounds in Diabetic Models</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Desmet, Céline M.; Lafosse, Aurore; Vériter, Sophie; Porporato, Paolo E.; Sonveaux, Pierre; Dufrane, Denis; Levêque, Philippe; Gallez, Bernard</p> <p>2015-01-01</p> <p>A lack of oxygen is classically described as a major cause of impaired wound healing in diabetic patients. Even if the role of oxygen in the wound healing process is well recognized, measurement of oxygen levels in a wound remains challenging. The purpose of the present study was to assess the value of electron paramagnetic resonance (EPR) <span class="hlt">oximetry</span> to monitor pO2 in wounds during the healing process in diabetic mouse models. Kinetics of wound closure were carried out in streptozotocin (STZ)-treated and db/db mice. The pO2 was followed repeatedly during the healing process by 1 GHz EPR spectroscopy with lithium phthalocyanine (LiPc) crystals used as oxygen sensor in two different wound models: a full-thickness excisional skin wound and a pedicled skin flap. Wound closure kinetics were dramatically slower in 12-week-old db/db compared to control (db/+) mice, whereas kinetics were not statistically different in STZ-treated compared to control mice. At the center of excisional wounds, measurements were highly influenced by atmospheric oxygen early in the healing process. In pedicled flaps, hypoxia was observed early after wounding. While reoxygenation occurred over time in db/+ mice, hypoxia was prolonged in the diabetic db/db model. This observation was consistent with impaired healing and microangiopathies observed using intravital microscopy. In conclusion, EPR <span class="hlt">oximetry</span> using LiPc crystals as the oxygen sensor is an appropriate technique to follow wound oxygenation in acute and chronic wounds, in normal and diabetic animals. Nevertheless, the technique is limited for measurements in pedicled skin flaps and cannot be applied to excisional wounds in which diffusion of atmospheric oxygen significantly affects the measurements. PMID:26659378</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3407336','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3407336"><span>Screening by Pulse CO-<span class="hlt">Oximetry</span> for Environmental Tobacco Smoke Exposure in Preanesthetic Children</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cardwell, Kathryn; Pan, Zhaoxing; Boucher, Rebecca; Zuk, Jeannie; Friesen, Robert H.</p> <p>2012-01-01</p> <p>Objective The purpose of this study was to evaluate the ability of multiple wavelength pulse CO-<span class="hlt">oximetry</span> (SpCO) to screen for environmental tobacco smoke (ETS) exposure in children. Background Exposure to ETS is associated with an increased risk of perioperative respiratory complications in children. It is often difficult to obtain an accurate history for ETS exposure, so a preoperative screening tool is desirable. Carbon monoxide is a measurable product of tobacco combustion. Multiple wavelength pulse CO-<span class="hlt">oximetry</span> is a recently developed point-of-care monitor. Methods Following IRB approval and parental consent, 220 children aged 1–16 years having outpatient surgical procedures were enrolled. SpCO was measured preoperatively 3 times with the Radical-7 Rainbow SET CO-oximeter (Masimo, Irvine, CA). Immediately following induction of anesthesia, a blood sample for laboratory measurement of carboxyhemoglobin (COHb) and serum cotinine was obtained. Regression analysis determined the correlation of SpCO with serum cotinine values. Receiver operator characteristic (ROC) curves analyzed the discriminating ability of SpCO or COHb to predict ETS exposure based on cotinine cutoff values known to be present in children exposed to ETS. Agreement of SpCO and COHb values was assessed using Bland-Altman plots. Results SpCO did not correlate with cotinine (R2=0.005). Both SpCO and COHb had poor discriminating ability for ETS exposure (area under the ROC curve = 0.606 and 0.562, respectively). SpCO values had poor agreement with COHb values. Conclusions The point-of-care multiple wavelength pulse CO-oximeter does not appear to be a useful preoperative screening tool for ETS exposure in children. PMID:22587734</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24725582','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24725582"><span>Respiratory outcomes of the surfactant positive pressure and <span class="hlt">oximetry</span> randomized trial (SUPPORT).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stevens, Timothy P; Finer, Neil N; Carlo, Waldemar A; Szilagyi, Peter G; Phelps, Dale L; Walsh, Michele C; Gantz, Marie G; Laptook, Abbot R; Yoder, Bradley A; Faix, Roger G; Newman, Jamie E; Das, Abhik; Do, Barbara T; Schibler, Kurt; Rich, Wade; Newman, Nancy S; Ehrenkranz, Richard A; Peralta-Carcelen, Myriam; Vohr, Betty R; Wilson-Costello, Deanne E; Yolton, Kimberly; Heyne, Roy J; Evans, Patricia W; Vaucher, Yvonne E; Adams-Chapman, Ira; McGowan, Elisabeth C; Bodnar, Anna; Pappas, Athina; Hintz, Susan R; Acarregui, Michael J; Fuller, Janell; Goldstein, Ricki F; Bauer, Charles R; O'Shea, T Michael; Myers, Gary J; Higgins, Rosemary D</p> <p>2014-08-01</p> <p>To explore the early childhood pulmonary outcomes of infants who participated in the National Institute of Child Health and Human Development's Surfactant Positive Airway Pressure and Pulse <span class="hlt">Oximetry</span> Randomized Trial (SUPPORT), using a factorial design that randomized extremely preterm infants to lower vs higher oxygen saturation targets and delivery room continuous positive airway pressure (CPAP) vs intubation/surfactant. The Breathing Outcomes Study, a prospective secondary study to the Surfactant Positive Airway Pressure and Pulse <span class="hlt">Oximetry</span> Randomized Trial, assessed respiratory morbidity at 6-month intervals from hospital discharge to 18-22 months corrected age (CA). Two prespecified primary outcomes-wheezing more than twice per week during the worst 2-week period and cough longer than 3 days without a cold-were compared for each randomized intervention. One or more interviews were completed for 918 of the 922 eligible infants. The incidences of wheezing and cough were 47.9% and 31.0%, respectively, and did not differ between the study arms of either randomized intervention. Infants randomized to lower vs higher oxygen saturation targets had a similar risk of death or respiratory morbidity (except for croup and treatment with oxygen or diuretics at home). Infants randomized to CPAP vs intubation/surfactant had fewer episodes of wheezing without a cold (28.9% vs 36.5%; P<.05), respiratory illnesses diagnosed by a doctor (47.7% vs 55.2%; P<.05), and physician or emergency room visits for breathing problems (68.0% vs 72.9%; P<.05) by 18-22 months CA. Treatment with early CPAP rather than intubation/surfactant is associated with less respiratory morbidity by 18-22 months CA. Longitudinal assessment of pulmonary morbidity is necessary to fully evaluate the potential benefits of respiratory interventions for neonates. Copyright © 2014 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26918319','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26918319"><span>Susceptibility-based time-resolved whole-organ and regional tissue <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wehrli, Felix W; Fan, Audrey P; Rodgers, Zachary B; Englund, Erin K; Langham, Michael C</p> <p>2017-04-01</p> <p>The magnetism of hemoglobin - being paramagnetic in its deoxy and diamagnetic in its oxy state - offers unique opportunities to probe oxygen metabolism in blood and tissues. The magnetic susceptibility χ of blood scales linearly with blood oxygen saturation, which can be obtained by measuring the magnetic field ΔB of the intravascular MR signal relative to tissue. In contrast to χ, the induced field ΔB is non-local. Therefore, to obtain the intravascular susceptibility Δχ relative to adjoining tissue from the measured ΔB demands solution of an inverse problem. Fortunately, for ellipsoidal structures, to which a straight, cylindrically shaped blood vessel segment conforms, the solution is trivial. The article reviews the principle of MR susceptometry-based blood <span class="hlt">oximetry</span>. It then discusses applications for quantification of whole-brain oxygen extraction - typically on the basis of a measurement in the superior sagittal sinus - and, in conjunction with total cerebral blood flow, the cerebral metabolic rate of oxygen (CMRO2 ). By simultaneously measuring flow and venous oxygen saturation (SvO2 ) a temporal resolution of a few seconds can be achieved, allowing the study of the response to non-steady-state challenges such as volitional apnea. Extensions to regional measurements in smaller cerebral veins are also possible, as well as voxelwise quantification of venous blood saturation in cerebral veins accomplished by quantitative susceptibility mapping (QSM) techniques. Applications of susceptometry-based <span class="hlt">oximetry</span> to studies of metabolic and degenerative disorders of the brain are reviewed. Lastly, the technique is shown to be applicable to other organ systems such as the extremities using SvO2 as a dynamic tracer to monitor the kinetics of the microvascular response to induced ischemia. Copyright © 2016 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28839307','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28839307"><span>Pulse <span class="hlt">oximetry</span> as a screening tool for critical congenital heart defects in newborns.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shahzad, Muhammad; Waqar, Talal; Irfan Waheed, Khawaja Ahmad; Gul, Rafia; Fatima, Syeda Tahseen</p> <p>2017-08-01</p> <p>To evaluate the effectiveness of pulse <span class="hlt">oximetry</span> as a screening tool for critical congenital heart defects in newborns. This cross-sectional study was conducted at the neonatology department of the Children's Hospital and the Institute of Child Health, Lahore, Pakistan, from January to June 2016, and comprised neonates aged up to 07 days. Babies with a prenatal diagnosis of heart defects and those whose parents refused to give consent were excluded. Oxygen saturation of enrolled patients was measured in right index finger (pre-ductal) and in the left big toe (post-ductal) subsequently. Echocardiography was done on all the enrolled babies to confirm the diagnosis. SPSS 19 was used for data analysis. Of the 145 babies initially enrolled, 138(95.2%) were included. The overall mean age of the babies was 2.17±1.62 days (range: <24 hours-07 days) whereas the mean birth weight was 2.95±0.47kg (range: <2.5->4kg). Babies with pre- and post-ductal oxygen saturation measurement difference of >3% showed a detection rate of 16(45.7%) for critical congenital heart defects. Sensitivity and specificity of this screening test was calculated to be 76.19% and 83.76%, respectively, while positive and negative predictive values were 45.71% and 95.15%, respectively. The measurement of pre- and post-ductal oxygen saturation by pulse <span class="hlt">oximetry</span> was an effective screening tool for the detection of critical congenital heart defects in newborns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11827182','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11827182"><span>Utilization of the walking <span class="hlt">oximetry</span> test to allow safe ambulation after pulmonary resection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kageyama, Y; Urabe, N; Chiba, A</p> <p>2001-01-01</p> <p>Supplemental oxygen therapy after pulmonary resection can generally be tapered according to arterial blood gases at rest or pulse <span class="hlt">oximetry</span> (SpO2). However, detecting exercise-induced oxygen desaturation can be difficult. We developed the walking <span class="hlt">oximetry</span> test (WOT) so that thoracotomy patients could be rehabilitated without the risk of undetected ambulatory hypoxemia. The subjects were 58 patients who had undergone pulmonary resection and could walk at the bedside, with oxygen at 3 l/min via a nasal cannula. Patients with a value of more than 100 torr were allowed to walk with assistance for 6 min in the corridor. The oxygen flow rate was kept at 3 l/min and the walking pace was less than 50 m/min. SpO2 was determined using a wristwatch pulse oximeter. The test was stopped if the SpO2 fell below 90% or there was a score of 5 or more on the Borg scale (range 1-10). Oxygen desaturation occurred in six patients (10%) during the WOT. These patients underwent ambulatory training with sufficient oxygen supplementation and were then tested again. Patients whose SpO2 values remained higher than 90% and who showed no more than 5% desaturation were permitted to walk in the corridor with oxygen at 3 l/min via a nasal cannula. All these patients had a Borg score of 4 or lower. The WOT is a reliable, nonvasive method for detecting exercise-induced oxygen desaturation during ambulation after pulmonary resection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T51F2674G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T51F2674G"><span>Joint Inversion of Receiver Functions and Surface <span class="hlt">Wave</span> Group Velocities from the MANAS data set to Determine Custal Thickness <span class="hlt">Variations</span> in theTien Shan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilligan, A.; Priestley, K. F.; Roecker, S. W.</p> <p>2012-12-01</p> <p>The Tien Shan is the largest active intracontinental orgogenic belt on the Earth. To better understand the processes causing mountains to form in this location distant from a plate boundary, we analyze passive source seismic data collected on 40 broad band stations of the MANAS project (2005-2007) to determine <span class="hlt">variations</span> in crustal thickness and wavespeed across the range. The linear MANAS array transects the Tien Shan just to the east of the Talas Fergana fault and extends from the Tarim Basin north over the Kokshal Range and across the Naryn Valley to the Kyrgyz Range and the Kazakh Shield. This data set has a denser station spacing (~10 km) than that available in previous studies. We combine P- and S-<span class="hlt">wave</span> receiver functions with surface <span class="hlt">wave</span> observations from both earthquakes and ambient noise analysis to reduce the ambiguity inherent in the images obtained from the techniques applied individually. In particular, fundamental-mode surface-<span class="hlt">wave</span> dispersion observations are sensitive to absolute wavespeed averages rather than contrasts, while receiver functions are primarily sensitive to wavespeed contrasts and vertically integrated travel times rather than absolute wavespeeds. Moreover, analysis of the ambient noise allows dispersion measurements at shorter periods which improves constraints for the upper crust. We jointly invert P- and S-<span class="hlt">wave</span> receiver functions, fundamental mode Rayleigh <span class="hlt">wave</span> group velocity determined from 1.75 years of continuous seismic ambient noise for periods 4-28s, and group velocity data for periods 10-70s from the surface <span class="hlt">wave</span> study of Acton et al. (2010). The resulting crustal model show a strong <span class="hlt">variation</span> in the Moho depth across the range. We find the thickest crust (~60 km) beneath the Kokshal range, while that beneath the Naryn Valley, in the middle of the Tien Shan is thin (~45 km) and is of similar thickness to that beneath the Tarim Basin and Kazakh shield. This suggests a lack of crustal shortening, or shortening of a previously</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSAH13A..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSAH13A..06F"><span>Climate-driven <span class="hlt">variations</span> in thermal forcing across a nearshore reef system during a marine heat <span class="hlt">wave</span> and its potential impact on coral calcification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Falter, J.; Zhang, Z.; Lowe, R.; Foster, T.; McCulloch, M. T.</p> <p>2016-02-01</p> <p>We examined the oceanic and atmospheric forces driving seasonal and spatial variability in water temperature across backreef and lagoonal habitats at Coral Bay at Ningaloo Reef, Western Australia before, during, and after a historically unprecedented marine heat <span class="hlt">wave</span> and resulting mass bleaching event in 2010-2011. Local deviations in the mean daily temperature of nearshore reef waters from offshore values were a linear function of the combined effect of net atmospheric heating and offshore <span class="hlt">wave</span> height and period . While intra-annual <span class="hlt">variation</span> in local heat exchange was driven mainly by seasonal changes in short-<span class="hlt">wave</span> radiation; intra-annual <span class="hlt">variation</span> in local cooling was driven mostly by changes in relative humidity (r2 = 0.60) and wind speed (r2 = 0.31) which exhibited no apparent seasonality. We demonstrate good agreement between nearshore reef temperatures modeled from offshore sea surface temperatures (SST), offshore <span class="hlt">wave</span> forcing, and local atmospheric heat fluxes with observed temperatures using a simple linear model (r2 = 0.31 to 0.69, root-mean-square error = 0.4°C to 0.9°C). Using these modeled nearshore reef temperature records, we show that during the heat <span class="hlt">wave</span> local thermal stresses across the reef reached as high as 18-34 °C-weeks and were being both intensified and accelerated by regional climate forcing when compared with offshore waters (12.6 °C-weeks max). Measurements of coral calcification made in Coral Bay following the bleaching event appear to lack any distinct seasonality; possibly due to the long-term effects of acute thermal stress. However, similarly minimal seasonality in calcification rates had also been observed in an Acropora-dominated community at Ningaloo years before the heat <span class="hlt">wave</span> as well as more recently in coral from regions in WA that had avoided mass bleaching. These observations, in conjunction with observations that most of the bleached communities within Coral Bay had recovered their color within 3-6 months of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ems..confE.235R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ems..confE.235R"><span>Effect of latitudinal <span class="hlt">variations</span> in low-level baroclinicity on eddy life cycles and upper-tropospheric <span class="hlt">wave</span>-breaking processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rivière, G.</p> <p>2009-09-01</p> <p>Storm tracks play a crucial role in the dynamics of the general circulation of the atmosphere and particularly of the teleconnections such as the North Atlantic Oscillation (NAO). Baroclinic <span class="hlt">waves</span> may displace the large-scale jets during their breaking with anticyclonic and cyclonic <span class="hlt">wave</span> breaking leading generally to a northward and southward displacement of the jets respectively. For example, it has been recently shown by different authors that the positive and the negative phases of the NAO are closely related to anticyclonic and cyclonic <span class="hlt">wave</span> breaking respectively. The purpose of our study is to look at the reverse side: the impact of the jet latitude onto <span class="hlt">wave</span>-breaking processes by performing idealized numerical simulations using a primitive-equation model on the sphere (the PUMA model). We first focus on normal mode analysis. By prescribing different types of jets, we study the effects of their latitude on normal mode structures and their breaking using nonlinear simulations. A second stage consists in forcing the model by relaxing the temperature field toward a given restoration temperature. Sensitivity runs are performed by using different restoration temperature fields to look at the effect of the latitude of the low-level baroclinicity on eddy life cycles. Implication for the eddy feedback onto the large-scale circulation is more precisely investigated. Our results reveal that eddies exert a positive feedback onto the latitudinal <span class="hlt">variations</span> of the large-scale jets. Finally, these results are used to interpret some <span class="hlt">wave</span>-breaking processes found in the observations of the Northern Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5096H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5096H"><span>Annual and inter-annual <span class="hlt">variations</span> of 6.5-day-planetary-<span class="hlt">waves</span> in MLT observed by TIMED/SABER</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Yingying; Li, Huijun; Li, Chongyin; Zhang, Shaodong</p> <p>2017-04-01</p> <p>Annual and inter-annual <span class="hlt">variations</span> of 6.5DWs in 20-110 km, 52°S-52°N, 2002-2016 are studied by using v2.0 TIMED/SABER kinetic temperature data. Firstly, global annual <span class="hlt">variations</span> of 6.5DW's spectral power and amplitudes are obtained. Strong <span class="hlt">wave</span> amplitudes emerge in 30°S/N-50°S/N, and peaks in altitude separate in stratosphere (40-50 km), mesosphere (80-90 km) and the lower thermosphere (100-110 km), respectively. Their annual <span class="hlt">variations</span> are similar in both hemispheres, but different in altitude. In 40-50 km, the annual maximums emerge mostly in winters: Dec.-Jan. in the NH and Jul.-Aug. in the SH. In MLT, annual peaks arise twice in each half of year. In 80-90 km, they're mainly in equinoctial seasons and winters: May, Aug.-Sep. and Jan. in the NH and Feb., Nov. and May in the SH. In 100-110 km, they emerge mainly in equinoctial seasons: Apr.-May and Aug.-Sep. in the NH and Feb.-Mar. and Oct.-Nov. in the SH. Then, inter-annual <span class="hlt">variations</span> of 6.5DW amplitudes during the 14-year period are studied. Frequency spectra of monthly-mean amplitudes show that, main dynamics in long-term <span class="hlt">variations</span> of 6.5DWs are AO and SAO in both hemispheres. Besides, QBO are visible in both hemispheres and 4-month period signals are noticed in the NH in MLT. Amplitudes of SAO, AO and QBO are obtained by bandpass filter. Their amplitudes are comparable in stratosphere and mesosphere, and QBO signals are weaker than the others in the LT. Vertical <span class="hlt">variations</span> both of SAO and AO amplitudes are very stable. AO structures have little inter-annual changes, while inter-annual <span class="hlt">variations</span> of SAO are significant and are related with 6.5DW. It means that annual and inter-annual <span class="hlt">variations</span> of 6.5DW are mainly controlled by AO and SAO, respectively. Although QBO signals are weaker and their <span class="hlt">variations</span> are less regular than AO and SAO, their phases seems to relate with inter-annual <span class="hlt">variations</span> of 6.5DW as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23089530','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23089530"><span>How to develop a business case to establish a neonatal pulse <span class="hlt">oximetry</span> programme for screening of congenital heart defects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ewer, Andrew K</p> <p>2012-12-01</p> <p>Pulse <span class="hlt">oximetry</span> screening for critical congenital heart defects (CCHDs) is a highly specific, moderately sensitive test which is cost effective, acceptable to both clinical staff and parents and meets the criteria for universal screening. Pulse <span class="hlt">oximetry</span> screening is gaining considerable worldwide support and last year was added to the recommended uniform screening panel in the USA following endorsement by the Health and Human Services Secretary. There is significant heterogeneity in published screening protocols and it is important to consider all available evidence and also take local factors into account when developing a screening programme, whether it is within an individual hospital, neonatal network or even at a national level. This paper presents available options based both on the published evidence and personal practice experience which will aid those considering the introduction of screening to make the right decisions both from a clinical and financial perspective.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28965726','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28965726"><span>[Pulse <span class="hlt">oximetry</span> screening of critical congenital heart defects in the neonatal period. The Spanish National Neonatal Society recommendation].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sánchez Luna, Manuel; Pérez Muñuzuri, Alejandro; Sanz López, Ester; Leante Castellanos, José Luis; Benavente Fernández, Isabel; Ruiz Campillo, César W; Sánchez Redondo, M Dolores; Vento Torres, Máximo; Rite Gracia, Segundo</p> <p>2017-09-28</p> <p>Due to its severity, as well as the consequences of a late diagnosis, critical congenital heart defects (CCHD) represent a challenging situation, making an early diagnosis necessary and ideally before symptoms appear when circulatory collapse or death of the newborn can occur. Due to this, a prenatal and very early postnatal diagnosis is very important. Prenatal ultrasound screening and physical examination of the newborn can miss a considerable number of CCHD cases. Pulse <span class="hlt">oximetry</span> screening has been demonstrated to be an effective, non-invasive, inexpensive, and well accepted tool in the early diagnosis of CCHD. The Spanish National Society of Neonatology, through its Standards Committee, and based on the current evidence, recommend the implementation of pulse <span class="hlt">oximetry</span> screening of CCHD in Spain, and then to offer the best therapy possible to these newborn infants. Copyright © 2017. Publicado por Elsevier España, S.L.U.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AAS...22911403P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AAS...22911403P"><span>Strong Evidence for the Density-<span class="hlt">Wave</span> Theory of Spiral Structure Based on <span class="hlt">Variations</span> in Pitch Angle When Viewed Across Optical and non-Optical Wavelengths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pour-Imani, Hamed; Kennefick, Daniel; Kennefick, Julia D.; Davis, Benjamin L.; Shields, Douglas W.; Shameer Abdeen, Mohamed</p> <p>2017-01-01</p> <p>The density-<span class="hlt">wave</span> theory of spiral structure, though first proposed as long ago as the mid-1960s by C.C. Lin and F. Shu, continues to be challenged by rival theories, such as the manifold theory. One test between these theories which has been proposed is that the pitch angle of spiral arms for galaxies should vary with the wavelength of the image in the density <span class="hlt">wave</span> theory, but not in the manifold theory. Density <span class="hlt">waves</span> are believed to create a spiral-shaped region of star formation in the gas of galactic disks. Stars born in the spiral arms of the galaxies move ahead of the density <span class="hlt">wave</span> inside the co-rotation radius, and fall behind outside of it. This implies that stars should exhibit tighter arms than the density <span class="hlt">wave</span> itself does. Thus wavelengths which image starlight should have measurably tighter pitch angles than wavelengths which image the star forming region itself (inside of which most starlight is obscured by gas and dust). Previous work, restricted to optical or near-optical wavelengths, either failed to find any significant <span class="hlt">variation</span> in pitch angle or only limited evidence for it in two or three cases.In this research, we took advantage of Spitzer and GALEX data to measure pitch angles of infrared and ultraviolet, in addition to optical, images of galaxies. We also used a larger sample size than any previously used to study this issue. For each galaxy we used four images with different pass bands (B-Band at around 445 nm, infrared at 3.6 and 8.0μm and ultraviolet at 151nm) and we measured the pitch angle in each of the four wavelengths with two independent algorithms (the 2DFFT code and Spirality). Each wavelength that we used images a different component or population of the disk. We find that for both sets of measurements (2DFFT and Spirality) the 8.0 micron and ultraviolet images agree in their pitch angle measurements, suggesting that they are, in fact, sensitive to the same region. By contrast the 3.6 micron and B-band images are uniformly tighter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27142098','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27142098"><span>Assessment of continuous acoustic respiratory rate monitoring as an addition to a pulse <span class="hlt">oximetry</span>-based patient surveillance system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McGrath, Susan P; Pyke, Joshua; Taenzer, Andreas H</p> <p>2016-05-03</p> <p>Technology advances make it possible to consider continuous acoustic respiratory rate monitoring as an integral component of physiologic surveillance systems. This study explores technical and logistical aspects of augmenting pulse <span class="hlt">oximetry</span>-based patient surveillance systems with continuous respiratory rate monitoring and offers some insight into the impact on patient deterioration detection that may result. Acoustic respiratory rate sensors were introduced to a general care pulse <span class="hlt">oximetry</span>-based surveillance system with respiratory rate alarms deactivated. Simulation was used after 4324 patient days to determine appropriate alarm thresholds for respiratory rate, which were then activated. Data were collected for an additional 4382 patient days. Physiologic parameters, alarm data, sensor utilization and patient/staff feedback were collected throughout the study and analyzed. No notable technical or workflow issues were observed. Sensor utilization was 57 %, with patient refusal leading reasons for nonuse (22.7 %). With respiratory rate alarm thresholds set to 6 and 40 breaths/min., the majority of nurse pager clinical notifications were triggered by low oxygen saturation values (43 %), followed by low respiratory rate values (21 %) and low pulse rate values (13 %). Mean respiratory rate collected was 16.6 ± 3.8 breaths/min. The vast majority (82 %) of low oxygen saturation states coincided with normal respiration rates of 12-20 breaths/min. Continuous respiratory rate monitoring can be successfully added to a pulse <span class="hlt">oximetry</span>-based surveillance system without significant technical, logistical or workflow issues and is moderately well-tolerated by patients. Respiratory rate sensor alarms did not significantly impact overall system alarm burden. Respiratory rate and oxygen saturation distributions suggest adding continuous respiratory rate monitoring to a pulse <span class="hlt">oximetry</span>-based surveillance system may not significantly improve patient deterioration detection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3910436','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3910436"><span>Accuracy of Conventional <span class="hlt">Oximetry</span> for Flow Estimation in Patients with Superior Cavopulmonary Connection: A Comparison with Phase-Contrast CMR</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Downing, Tacy E.; Whitehead, Kevin K.; Dori, Yoav; Gillespie, Matthew J.; Harris, Matthew A.; Fogel, Mark A.; Rome, Jonathan J.; Glatz, Andrew C.</p> <p>2014-01-01</p> <p>Background Cardiac catheterization is routinely used as a diagnostic tool in single ventricle patients with superior cavopulmonary connection (SCPC). This physiology presents inherent challenges in applying the Fick principle to estimate flow. We sought to quantitatively define the error in <span class="hlt">oximetry</span>-derived flow parameters, using phase-contrast cardiac MRI (CMR) as a reference. Methods and Results Thirty patients with SCPC who underwent combined cardiac MRI and catheterization between July 2008 and June 2012 were retrospectively analyzed. Estimates of flow and resistance calculated using the Fick equation were compared to CMR measurements. <span class="hlt">Oximetry</span> underestimated CMR-measured pulmonary blood flow (Qp) by an average of 1.1 L/min/m2, or 32% of the CMR value (p < .0001). <span class="hlt">Oximetry</span> overestimated systemic blood flow (Qs) by an average of 0.5 L/min/m2, or 15% of the CMR value (p = .009). There was no correlation between the Qp:Qs ratio derived by Fick and that measured by CMR (ρc = 0.01). The error in Fick Qp correlated moderately with the measured systemic to pulmonary arterial collateral flow (r =0.39). The median total oxygen consumption calculated using combined CMR and <span class="hlt">oximetry</span> data was 173 mL/min/m2, higher than the assumed values used to calculate flows by the Fick equation. The upper body circulation received on average 51% of systemic blood flow while conducting only 39% of total body metabolism. Conclusions Fick-derived estimates of flow are inherently unreliable in patients with superior cavopulmonary connections. Integrating flows measured by CMR and pressures measured by catheter will provide the best characterization of SCPC physiology. PMID:24097418</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23679994','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23679994"><span>Pulse <span class="hlt">oximetry</span> in the pulmonary tissue for the non-invasive measurement of mixed venous oxygen saturation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nitzan, Meir; Nitzan, Itamar</p> <p>2013-08-01</p> <p>The oxygen saturation of the systemic arterial blood is associated with the adequacy of respiration, and can be measured non-invasively by pulse <span class="hlt">oximetry</span> in the systemic tissue. The oxygen saturation of the blood in the pulmonary artery, the mixed venous blood, reflects the balance between oxygen supply to the systemic tissues and their oxygen demand. The mixed venous oxygen saturation has also clinical significance because it is used in Fick equation for the quantitative measurement of cardiac output. At present the measurement of the mixed venous oxygen saturation is invasive and requires insertion of a Swan-Ganz catheter into the pulmonary artery. We suggest a noninvasive method for the measurement of the mixed venous oxygen saturation in infants, pulmonary pulse <span class="hlt">oximetry</span>. The method is similar to the systemic pulse <span class="hlt">oximetry</span>, which is based on the different light absorption curves of oxygenated and deoxygenated hemoglobin and on the analysis of photoplethysmographic curves in two wavelengths. The proposed pulmonary pulse oximeter includes light-sources of two wavelengths in the infrared, which illuminate the pulmonary tissue through the thoracic wall. Part of the light which is scattered back from the pulmonary tissue and passes through the thoracic wall is detected, and for each wavelength a pulmonary photoplethysmographic curve is obtained. The pulmonary photoplethysmographic curves reflect blood volume increase during systole in the pulmonary arteries in the lung tissue, which contain mixed venous blood. The ratio R of the amplitude-to-baseline ratio for the two wavelengths is related to the mixed venous oxygen saturation through equations derived for the systemic pulse <span class="hlt">oximetry</span>. The method requires the use of extinction coefficients values for oxygenated and deoxygenated hemoglobin, which can be found in the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.779G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.779G"><span>On the altitude-<span class="hlt">variation</span> of electron acceleration by HF radio-<span class="hlt">waves</span> in the F-region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gustavsson, Bjorn</p> <p>2016-07-01</p> <p>I will talk about artificial aurora, the descending layers we have observed at HAARP and the altitude-<span class="hlt">variations</span> we have observed in enhanced ion and plasma-lines with the EISCAT UHF-radar, and present an empirical model describing these phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2921178','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2921178"><span>Repetitive Tissue PO2 Measurements by Electron Paramagnetic Resonance <span class="hlt">Oximetry</span>: Current Status and Future Potential for Experimental and Clinical Studies</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>KHAN, NADEEM; WILLIAMS, BENJAMIN B.; HOU, HUAGANG; LI, HONGBIN; SWARTZ, HAROLD M.</p> <p>2010-01-01</p> <p>Tissue oxygen plays a crucial role in maintaining tissue viability and in various diseases, including responses to therapy. Useful knowledge has been gained by methods that can give limited snapshots of tissue oxygen (e.g., oxygen electrodes) or evidence of a history of tissue hypoxia (e.g., EF5) or even indirect evidence by monitoring oxygen availability in the circulatory system (e.g., NMR methods). Each of these methods has advantages and significant limitations. EPR <span class="hlt">oximetry</span> is a technique for direct measurement of tissue pO2, which has several advantages over the other existing methods for applications in which the parameter of interest is the pO2 of tissues, and information is needed over a time course of minutes to hours, and/or for repetitive measurements over days or weeks or years. The aim of this article is to provide an overview of EPR <span class="hlt">oximetry</span> using particulates to readers who are not familiar with this technique and its potential in vivo and clinical applications. The data presented here are from the experiments currently being carried out in our laboratory. We are confident that in vivo EPR <span class="hlt">oximetry</span> will play a crucial role in the understanding and clinical management of various pathologies in the years to come. PMID:17536960</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21344072','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21344072"><span>Quantitative impact of small angle forward scatter on whole blood <span class="hlt">oximetry</span> using a Beer-Lambert absorbance model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>LeBlanc, Serge Emile; Atanya, Monica; Burns, Kevin; Munger, Rejean</p> <p>2011-04-21</p> <p>It is well known that red blood cell scattering has an impact on whole blood <span class="hlt">oximetry</span> as well as in vivo retinal oxygen saturation measurements. The goal of this study was to quantify the impact of small angle forward scatter on whole blood <span class="hlt">oximetry</span> for scattering angles found in retinal <span class="hlt">oximetry</span> light paths. Transmittance spectra of whole blood were measured in two different experimental setups: one that included small angle scatter in the transmitted signal and one that measured the transmitted signal only, at absorbance path lengths of 25, 50, 100, 250 and 500 µm. Oxygen saturation was determined by multiple linear regression in the 520-600 nm wavelength range and compared between path lengths and experimental setups. Mean calculated oxygen saturation differences between setups were greater than 10% at every absorbance path length. The deviations to the Beer-Lambert absorbance model had different spectral dependences between experimental setups, with the highest deviations found in the 520-540 nm range when scatter was added to the transmitted signal. These results are consistent with other models of forward scatter that predict different spectral dependences of the red blood cell scattering cross-section and haemoglobin extinction coefficients in this wavelength range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EP%26S...69..112F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EP%26S...69..112F"><span>Geomagnetically conjugate observations of ionospheric and thermospheric <span class="hlt">variations</span> accompanied by a midnight brightness <span class="hlt">wave</span> at low latitudes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.</p> <p>2017-08-01</p> <p>We conducted geomagnetically conjugate observations of 630-nm airglow for a midnight brightness <span class="hlt">wave</span> (MBW) at Kototabang, Indonesia [geomagnetic latitude (MLAT): 10.0°S], and Chiang Mai, Thailand (MLAT: 8.9°N), which are geomagnetically conjugate points at low latitudes. An airglow enhancement that was considered to be an MBW was observed in OI (630-nm) airglow images at Kototabang around local midnight from 2240 to 2430 LT on February 7, 2011. This MBW propagated south-southwestward, which is geomagnetically poleward, at a velocity of 290 m/s. However, a similar <span class="hlt">wave</span> was not observed in the 630-nm airglow images at Chiang Mai. This is the first evidence of an MBW that does not have geomagnetic conjugacy, which also implies generation of MBW only in one side of the hemisphere from the equator. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the <span class="hlt">wave</span> was observed. This indicates that the observed MBW was generated by the poleward winds which push ionospheric plasma down along geomagnetic field lines, thereby increasing the 630-nm airglow intensity. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai. We suggest that the polarization electric field inside the observed MBW is projected to the northern hemisphere, causing the small height increase observed at Chiang Mai. This implies that electromagnetic coupling between hemispheres can occur even though the original disturbance is caused purely by the neutral wind.[Figure not available: see fulltext.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvE..90d2718M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvE..90d2718M"><span>Noise, transient dynamics, and the generation of realistic interspike interval <span class="hlt">variation</span> in square-<span class="hlt">wave</span> burster neurons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marin, Bóris; Pinto, Reynaldo Daniel; Elson, Robert C.; Colli, Eduardo</p> <p>2014-10-01</p> <p>First return maps of interspike intervals for biological neurons that generate repetitive bursts of impulses can display stereotyped structures (neuronal signatures). Such structures have been linked to the possibility of multicoding and multifunctionality in neural networks that produce and control rhythmical motor patterns. In some cases, isolating the neurons from their synaptic network reveals irregular, complex signatures that have been regarded as evidence of intrinsic, chaotic behavior. We show that incorporation of dynamical noise into minimal neuron models of square-<span class="hlt">wave</span> bursting (either conductance-based or abstract) produces signatures akin to those observed in biological examples, without the need for fine tuning of parameters or ad hoc constructions for inducing chaotic activity. The form of the stochastic term is not strongly constrained and can approximate several possible sources of noise, e.g., random channel gating or synaptic bombardment. The cornerstone of this signature generation mechanism is the rich, transient, but deterministic dynamics inherent in the square-<span class="hlt">wave</span> (saddle-node and homoclinic) mode of neuronal bursting. We show that noise causes the dynamics to populate a complex transient scaffolding or skeleton in state space, even for models that (without added noise) generate only periodic activity (whether in bursting or tonic spiking mode).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22423788','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22423788"><span>In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR <span class="hlt">oximetry</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Weaver, John; Yang, Yirong; Purvis, Rebecca; Weatherwax, Theodore; Rosen, Gerald M.; Liu, Ke Jian</p> <p>2014-03-01</p> <p>Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O{sub 2} may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O{sub 2} is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO{sub 2}in vivo remains largely uncharacterized. This study investigated striatal tissue pO{sub 2} changes in male C57BL/6 mice (16–20 g) following METH administration using EPR <span class="hlt">oximetry</span>, a highly sensitive modality to measure pO{sub 2}in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO{sub 2} was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO{sub 2} to 64%. More importantly, pO{sub 2} did not recover fully to control levels even 24 h after administration of a single dose of METH and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO{sub 2} indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO{sub 2}, which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. - Highlights: • Explored striatal tissue pO{sub 2}in vivo after METH administration by EPR <span class="hlt">oximetry</span>. • pO{sub 2} was reduced by 81% after a single dose and 64% after 3 consecutive daily doses. • pO{sub 2} did not recover fully to control levels even 24 h after a single dose. • Decrease in brain tissue pO{sub 2} may be associated with a decrease in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9358923','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9358923"><span>Nocturnal oxygen desaturation, as assessed by home <span class="hlt">oximetry</span>, in long-term solvent-exposed workers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laire, G; Viaene, M K; Veulemans, H; Masschelein, R; Nemery, B</p> <p>1997-12-01</p> <p>Recent studies have suggested that occupational exposure to solvents may be a cause of sleep apnea. Digital <span class="hlt">oximetry</span> during one night was performed in solvent-exposed offset printers (n = 21) and in a control group (n = 21), using a Palco 400 Pulse Oximeter. The threshold for recording was set at an arterial oxygen saturation (SaO2) of 90%. Furthermore, computerized neurobehavioral tests (NES) and a solvent-related complaints questionnaire (NSC-60) were administered. The mean exposure time was 15 years (SD = 10). Hygiene measurements revealed a large number of different solvents and a cumulative exposure between 15% and 97% of the "cumulative TLV." The exposed workers had more solvent-related complaints, especially regarding mood (analysis of covariance, P = 0.02), than the nonexposed workers. The neurobehavioral tests indicated that hand-eye coordination was significantly worse in the exposed group (analysis of covariance, P = 0.03). The frequency of nocturnal desaturation was significantly higher in the printers (1.7 events/hr +/- SD = 1.5) than in the controls (0.6 events/hr +/- SD = 1.3) (Mann-Whitney test, P < 0.01). Also, the duration of desaturation was longer in the exposed workers: 3.2 min/hr (SD = 3.2) vs 1.2 min/hr (SD = 2.3) (Mann-Whitney test, P < 0.01). In the analysis of covariance, exposure (P = 0.04) and the interaction between smoking and exposure (P = 0.02) were shown to contribute significantly to the excess of nocturnal desaturation in the exposed. The same was true for the mean duration of desaturation (exposure: P = 0.02 and interaction exposure smoking: P = 0.02). The significant interaction was due to a more pronounced effect of solvent exposure among the nonsmoker group. No relation was found between the excess of complaints or the neuroperformance effects and the <span class="hlt">oximetry</span> data. These data reinforce the presumption that occupational solvent exposure might contribute to sleep-disordered breathing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2410T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2410T"><span>Temporal <span class="hlt">variation</span> of the Rayleigh admittance: Implication for S-<span class="hlt">wave</span> velocity changes in the toe of the Nankai accretionary prism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tonegawa, Takashi; Araki, Eiichiro; Kimura, Toshinori; Nakamura, Takeshi</p> <p>2016-04-01</p> <p>A cabled seafloor network with 20 stations (DONET: Dense Oceanfloor Network System for Earthquake and Tsunamis) has been constructed on the accretionary prism at the Nankai subduction zone of Japan between March 2010 and August 2011, which means that the observation period became more than 4 years. Each station contains broadband seismometers and absolute and differential pressure gauges. In this study, we estimated the Rayleigh admittance at the seafloor for each station, i.e., an amplitude transfer function from pressure to displacement in the frequency band of microseisms, particularly for the fundamental Rayleigh mode of 0.1-0.2 Hz. The pattern of the transfer function depends on the S-<span class="hlt">wave</span> velocity structure at shallow depths beneath stations (Ruan et al., 2014, JGR). Therefore, plotting the Rayleigh admittance as functions of time and frequency, we investigated temporal <span class="hlt">variations</span> of S-<span class="hlt">wave</span> velocity within the accretionary prism. We calculated the displacement seismogram by removing the instrument response from the velocity seismogram for each station. The pressure record observed at the differential pressure gauge was used in this study because of a high resolution of the pressure observation. In the frequency domain, we smoothed the two kinds of spectra (displacement and pressure) with ±2 neighboring samples, and estimated the amplitude transfer function of displacement/pressure. Here, we used the ambient noise of the two records. To display their temporal <span class="hlt">variations</span>, we plot the averaged transfer function with intervals of 7 days. As a result, we found a long-term temporal <span class="hlt">variation</span> of the Rayleigh admittance at two stations. These stations are located at the southern part of the array and near the trench, where the activities of very-low frequency earthquakes (VLFEs) within the accretionary prism on 2004, 2009, and 2011 have been previously reported. The admittance at a frequency of 0.1 Hz has gradually decreased during the observation period, which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JCoPh.182..118M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JCoPh.182..118M"><span>Implementation of the <span class="hlt">Variational</span> Riemann Problem Solution for Calculating Propagation of Sound <span class="hlt">Waves</span> in Nonuniform Flow Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Men'shov, Igor; Nakamura, Yoshiaki</p> <p>2002-10-01</p> <p>The <span class="hlt">variational</span> Riemann problem (VRP) is defined as the first <span class="hlt">variation</span> of the solution to Riemann's initial-value problem, also known as the problem of breakup of an arbitrary discontinuity in a gas, when the initial data undergo small <span class="hlt">variations</span>. We show that the solution to the VRP can be analytically obtained, provided that the solution to the baseline Riemann problem is known. This solution describes the interaction of two abutting parcels of small disturbances against the background of a given base flow and therefore can be efficiently implemented in numerical methods for aeroacoustics. When the spatial distribution of disturbances and base flow parameters are given at a time moment at mesh points of a computational grid, one can exactly determine the disturbance evolution for a short lapse of time by solving the VRP at mesh interfaces. This can then be applied to update disturbance values to a new time moment by using the standard finite-volume scheme. In other words, the VRP can be used in computational aeroacoustics in the similar way to the Riemann problem used in Godunov-type methods for computational fluid dynamics. The present paper elaborates on this idea and adopts the solution to the VRP as a building block for a finite-volume Godunov-type method for aeroacoustics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.207.1080C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.207.1080C"><span>Three-dimensional elastic <span class="hlt">wave</span> speeds in the northern Chile subduction zone: <span class="hlt">variations</span> in hydration in the supraslab mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Comte, Diana; Carrizo, Daniel; Roecker, Steven; Ortega-Culaciati, Francisco; Peyrat, Sophie</p> <p>2016-11-01</p> <p>We use seismic tomography to investigate the state of the supraslab mantle beneath northern Chile, a part of the Nazca-South America Plate boundary known for frequent megathrust earthquakes and active volcanism. We performed a joint inversion of arrival times from earthquake generated body <span class="hlt">waves</span> and phase delay times from ambient noise generated surface <span class="hlt">waves</span> recorded by a combined 360 seismic stations deployed in northern Chile at various times over several decades. Our preferred model shows an increase in Vp/Vs by as much as 3 per cent from the subducting slab into the supraslab mantle throughout northern Chile. Combined with low values of both Vp and Vs at depths between 40 and 80 km, we attribute this increase in Vp/Vs to the serpentinization of the supraslab mantle in this depth range. The region of high Vp/Vs extends to 80-120 km depth within the supraslab mantle, but Vp and Vs both increase to normal to high values. This combination, along with the greater abundance of ambient seismicity and higher temperatures at these depths, suggest that conversion from basalt to eclogite in the slab accelerates and that the fluids expelled into the supraslab mantle contribute to partial melt. The corresponding maximum melt fraction is estimated to be about 1 per cent. Both the volume of the region affected by hydration and size of the <span class="hlt">wave</span> speed contrasts are significantly larger north of ˜21°S. This latitude also delimits large coastal scarps and the eruption of ignimbrites in the north. Ambient seismicity is more abundant north of 21°S, and the seismic zone south of this latitude is offset to the east. The high Vp/Vs region in the north may extend along the slab interface to depths as shallow as 20 km, where it corresponds to a region of reduced seismic coupling and overlaps the rupture zone of the recent 2014 M8.2 Pisagua earthquake. A potential cause of these contrasts is enhanced hydration of the subducting oceanic lithosphere related to a string of seamounts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNS41B1935O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNS41B1935O"><span>Determination of Bedrock <span class="hlt">Variations</span> and S-<span class="hlt">wave</span> Velocity Structure in the NW part of Turkey for Earthquake Hazard Mitigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ozel, A. O.; Arslan, M. S.; Aksahin, B. B.; Genc, T.; Isseven, T.; Tuncer, M. K.</p> <p>2015-12-01</p> <p>Tekirdag region (NW Turkey) is quite close to the North Anatolian Fault which is capable of producing a large earthquake. Therefore, earthquake hazard mitigation studies are important for the urban areas close to the major faults. From this point of view, integration of different geophysical methods has important role for the study of seismic hazard problems including seismotectonic zoning. On the other hand, geological mapping and determining the subsurface structure, which is a key to assist management of new developed areas, conversion of current urban areas or assessment of urban geological hazards can be performed by integrated geophysical methods. This study has been performed in the frame of a national project, which is a complimentary project of the cooperative project between Turkey and Japan (JICA&JST), named as "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education". With this principal aim, this study is focused on Tekirdag and its surrounding region (NW of Turkey) where some uncertainties in subsurface knowledge (maps of bedrock depth, thickness of quaternary sediments, basin geometry and seismic velocity structure,) need to be resolved. Several geophysical methods (microgravity, magnetic and single station and array microtremor measurements) are applied and the results are evaluated to characterize lithological changes in the region. Array microtremor measurements with several radiuses are taken in 30 locations and 1D-velocity structures of S-<span class="hlt">waves</span> are determined by the inversion of phase velocities of surface <span class="hlt">waves</span>, and the results of 1D structures are verified by theoretical Rayleigh <span class="hlt">wave</span> modelling. Following the array measurements, single-station microtremor measurements are implemented at 75 locations to determine the predominant frequency distribution. The predominant frequencies in the region range from 0.5 Hz to 8 Hz in study area. On the other hand, microgravity and magnetic measurements are performed on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914172L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914172L"><span>Predicting location-specific extreme coastal floods in the future climate by introducing a probabilistic method to calculate maximum elevation of the continuous water mass caused by a combination of water level <span class="hlt">variations</span> and wind <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leijala, Ulpu; Björkqvist, Jan-Victor; Johansson, Milla M.; Pellikka, Havu</p> <p>2017-04-01</p> <p>Future coastal management continuously strives for more location-exact and precise methods to investigate possible extreme sea level events and to face flooding hazards in the most appropriate way. Evaluating future flooding risks by understanding the behaviour of the joint effect of sea level <span class="hlt">variations</span> and wind <span class="hlt">waves</span> is one of the means to make more comprehensive flooding hazard analysis, and may at first seem like a straightforward task to solve. Nevertheless, challenges and limitations such as availability of time series of the sea level and <span class="hlt">wave</span> height components, the quality of data, significant locational variability of coastal <span class="hlt">wave</span> height, as well as assumptions to be made depending on the study location, make the task more complicated. In this study, we present a statistical method for combining location-specific probability distributions of water level <span class="hlt">variations</span> (including local sea level observations and global mean sea level rise) and <span class="hlt">wave</span> run-up (based on <span class="hlt">wave</span> buoy measurements). The goal of our method is to obtain a more accurate way to account for the <span class="hlt">waves</span> when making flooding hazard analysis on the coast compared to the approach of adding a separate fixed <span class="hlt">wave</span> action height on top of sea level -based flood risk estimates. As a result of our new method, we gain maximum elevation heights with different return periods of the continuous water mass caused by a combination of both phenomena, "the green water". We also introduce a sensitivity analysis to evaluate the properties and functioning of our method. The sensitivity test is based on using theoretical <span class="hlt">wave</span> distributions representing different alternatives of <span class="hlt">wave</span> behaviour in relation to sea level <span class="hlt">variations</span>. As these <span class="hlt">wave</span> distributions are merged with the sea level distribution, we get information on how the different <span class="hlt">wave</span> height conditions and shape of the <span class="hlt">wave</span> height distribution influence the joint results. Our method presented here can be used as an advanced tool to minimize over- and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QS%26T....2c4015O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QS%26T....2c4015O"><span>Spectral tunability of two-photon states generated by spontaneous four-<span class="hlt">wave</span> mixing: fibre tapering, temperature <span class="hlt">variation</span> and longitudinal stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortiz-Ricardo, E.; Bertoni-Ocampo, C.; Ibarra-Borja, Z.; Ramirez-Alarcon, R.; Cruz-Delgado, D.; Cruz-Ramirez, H.; Garay-Palmett, K.; U'Ren, A. B.</p> <p>2017-09-01</p> <p>We explore three different mechanisms designed to controllably tune the joint spectrum of photon pairs produced by the spontaneous four-<span class="hlt">wave</span> mixing (SFWM) process in optical fibres. The first of these is fibre tapering, which exploits the modified optical dispersion resulting from reducing the core radius. We have presented a theory of SFWM for tapered fibres, as well as experimental results for the SFWM coincidence spectra as a function of the reduction in core radius due to tapering. The other two techniques that we have explored are temperature <span class="hlt">variation</span> and application of longitudinal stress. While the maximum spectral shift observed with these two techniques is smaller than for fibre tapering, they are considerably simpler to implement and have the important advantage that they are based on the use of a single, suitably controlled, fibre specimen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24c2308E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24c2308E"><span>New: <span class="hlt">Variational</span> principle-exact solutions and conservation laws for modified ion-acoustic shock <span class="hlt">waves</span> and double layers with electron degenerate in plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>EL-Kalaawy, O. H.</p> <p>2017-03-01</p> <p>The nonlinear propagation of modified ion acoustic shock <span class="hlt">waves</span> and double layers in a relativistic degenerate plasma is considered. This plasma system is proposed for containing inertial viscous positive and negative ion fluids, relativistic electron fluids, and negatively charged immobile heavy ions. The basic set of fluid equations is reduced to modified Burgers (MB) and further modified Burgers (FMB) or (Gardner) or Mamun and Zobaer (M-Z) equations by using the reductive perturbation method. The basic features of these shocks obtained from this analysis are observed to be significantly different from those obtained from the standard Burgers equation. By introducing two special functions and He's semi-inverse method, a <span class="hlt">variational</span> principle and conservation laws for the Gardner (FmB) equation are obtained. A set of new exact solutions for the Gardner (FmB) equation are obtained by the auto-Bäcklund transformations. Finally, we will study the physical meanings of solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5307C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5307C"><span>Annual, semi-annual and ter-annual <span class="hlt">variations</span> of gravity <span class="hlt">wave</span> momentum flux in 13 years of SABER data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Dan; Preusse, Peter; Ern, Manfred; Strube, Cornelia</p> <p>2017-04-01</p> <p>In this study, the <span class="hlt">variations</span> at different time scales such as the annual cycle, the semiannual oscillation (SAO), the ter-annual cycle (about four monthly) and the quasi-biennial oscillation (QBO) in zonal mean GW amplitudes and GW momentum flux (GWMF) have been investigated using satellite observations from 2002-2014 and combining ECMWF high resolution data with the GORGRAT model. The global distribution (patterns) of spectral amplitudes of GW momentum flux in stratosphere and mesosphere (from 30 km to 90 km) show that the annual cycle is the most predominant <span class="hlt">variation</span>, and then are SAO, ter-annual cycle and QBO. For annual components, two relatively isolated amplitude maxima appear in each hemisphere: a subtropical maximum is associated with convective sources in summer, a mid and high latitude maximum is associated with the polar vortex in winter. In the subtropics, GWs propagate upward obliquely to the higher latitudes. The winter maximum in the southern hemisphere has larger momentum flux than that one in the northern hemisphere. While on the SH the phase (i.e. time corresponding to the maximum GWMF) continuously descends with the maximum in July in the upper mesosphere and in September in the lower stratosphere, on the northern hemisphere, the phase has no visible altitude dependence with a maximum in December. For semiannual <span class="hlt">variations</span>, in the MLT (70-80 km) region, there is an obvious enhancement of spectral amplitude at equatorial latitudes which relate to the dissipation of convectively forced GWs. The SAO in absolute momentum flux and the annual cycle in zonal momentum flux indicated that the <span class="hlt">variations</span> at mid-latitudes (about from 30°-40°) are not a SAO signals but rather an annual cycle when the direction of GWMF is considered. The ter-annual cycle may be related to the duration of active convection in subtropical latitudes (from June to Sep. in north hemisphere) Indications for QBO are found latitude extension to mid-latitudes in stratosphere of</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27603538','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27603538"><span>Newborn Critical Congenital Heart Disease Screening Using Pulse <span class="hlt">Oximetry</span>: Nursing Aspects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hom, Lisa A; Martin, Gerard R</p> <p>2016-09-01</p> <p>Congenital heart disease (CCHD) is the most common birth defect. Screening for the most critical forms (CCHD) using pulse <span class="hlt">oximetry</span> was added to the Recommended Uniform Screening Panel in the United States in 2011. Since then, CCHD screening has become nearly universal in the United States. Nurses are ideally situated to contribute to the development of best practices for implementation and provide education to families on CCHD screening. Much of the standardization, advocacy, and development of national recommendations occurred with key input from nurses. Nurses often have responsibility for educating parents, performing the screening, interpreting the screening algorithm, and the documentation of results. The nurse role often includes implementing follow-up quality improvement initiatives to ensure that systematic and accurate screening occurs. Smooth implementation can be achieved by identifying champions early, obtaining input from a multidisciplinary team including both physician and nursing leaders, and identifying ways to integrate screening into already existing workflow. By knowing the basics of why screening is important, how to screen, current recommendations on the follow-up for positive screens and the limitations of CCHD screening, nurses can advocate for their patients and positively impact outcomes for infants born with CCHD through early identification before discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21224001','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21224001"><span>Using pulse <span class="hlt">oximetry</span> to account for high and low frequency physiological artifacts in the BOLD signal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Verstynen, Timothy D; Deshpande, Vibhas</p> <p>2011-04-15</p> <p>The BOLD signal not only reflects changes in local neural activity, but also exhibits variability from physiological processes like cardiac rhythms and breathing. We investigated how both of these physiological sources are reflected in the pulse <span class="hlt">oximetry</span> (PO) signal, a direct measure of blood oxygenation, and how this information can be used to account for different types of noise in the BOLD response. Measures of heart rate, respiration and PO were simultaneously recorded while neurologically healthy participants performed an eye-movement task in a 3T MRI. PO exhibited power in frequencies that matched those found in the independently recorded cardiac and respiration signals. Using the phasic and aphasic properties of these signals as nuisance regressors, we found that the different frequency components of the PO signal could be used to identify different types of physiological artifacts in the BOLD response. A comparison of different physiological noise models found that a simple, down-sampled version of the PO signal improves the estimation of task-relevant statistics nearly as well as more established noise models that may run the risk of over-parameterization. These findings suggest that the PO signal captures multiple sources of physiological noise in the BOLD response and provides a simple and efficient way of modeling these noise sources in subsequent analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OptRv..23..955K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OptRv..23..955K"><span>Correction method for influence of tissue scattering for sidestream dark-field <span class="hlt">oximetry</span> using multicolor LEDs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kurata, Tomohiro; Oda, Shigeto; Kawahira, Hiroshi; Haneishi, Hideaki</p> <p>2016-12-01</p> <p>We have previously proposed an estimation method of intravascular oxygen saturation (SO_2) from the images obtained by sidestream dark-field (SDF) imaging (we call it SDF <span class="hlt">oximetry</span>) and we investigated its fundamental characteristics by Monte Carlo simulation. In this paper, we propose a correction method for scattering by the tissue and performed experiments with turbid phantoms as well as Monte Carlo simulation experiments to investigate the influence of the tissue scattering in the SDF imaging. In the estimation method, we used modified extinction coefficients of hemoglobin called average extinction coefficients (AECs) to correct the influence from the bandwidth of the illumination sources, the imaging camera characteristics, and the tissue scattering. We estimate the scattering coefficient of the tissue from the maximum slope of pixel value profile along a line perpendicular to the blood vessel running direction in an SDF image and correct AECs using the scattering coefficient. To evaluate the proposed method, we developed a trial SDF probe to obtain three-band images by switching multicolor light-emitting diodes and obtained the image of turbid phantoms comprised of agar powder, fat emulsion, and bovine blood-filled glass tubes. As a result, we found that the increase of scattering by the phantom body brought about the decrease of the AECs. The experimental results showed that the use of suitable values for AECs led to more accurate SO_2 estimation. We also confirmed the validity of the proposed correction method to improve the accuracy of the SO_2 estimation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14726125','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14726125"><span>In vivo study of different ointments for drug delivery into oral mucosa by EPR <span class="hlt">oximetry</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Petelin, Milan; Pavlica, Zlatko; Bizimoska, Saska; Sentjurc, Marjeta</p> <p>2004-02-11</p> <p>The aim of the present study was to determine the rate of transport and long-term effect of a drug applied to the oral mucosa in different ointments. Three ointments with bioadhesive properties: Orabase, Carbopol 935P, and polymethyl methacrylate (PMM) and the ointment Miglyol without such properties were used. Benzyl nicotinate (BN) was used as an active ingredient that causes hyperemia. The kinetics of drug action was measured by electron paramagnetic resonance (EPR) <span class="hlt">oximetry</span> in vivo using the paramagnetic probe (Lithium phthalocyanine) implanted beneath the epithelium of the buccal mucosa in rats. EPR spectra line-width was proportional to local changes of partial pressure of oxygen (pO(2)) in tissue and was monitored for 90 min after the application of ointments mixed with BN. The greatest increase in pO(2) and the highest efficiency of drug action was observed after the application of 2% BN in PMM (P<0.01). Additionally in PMM the drug effect increased linearly with BN concentration up to 3%, at higher concentrations (3.5 and 4% BN) no further effect was observed. The results demonstrated that the greatest and the longest effect caused by a hyperemic drug in PMM. By increasing the concentration of the drug in PMM higher pO(2) in the oral mucosa can be established but only until the saturation is reached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23543306','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23543306"><span>Monitoring respiration in wheezy preschool children by pulse <span class="hlt">oximetry</span> plethysmogram analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wertheim, David; Olden, Cathy; Symes, Liz; Rabe, Heike; Seddon, Paul</p> <p>2013-09-01</p> <p>The aim of this study was to investigate whether respiratory information can be derived from pulse <span class="hlt">oximetry</span> plethysmogram (pleth) recordings in acutely wheezy preschool children. A digital pulse oximeter was connected via 'Bluetooth' to a notebook computer in order to acquire pleth data. Low pass filtering and frequency analysis were used to derive respiratory rate from the pleth trace; the ratio of heart rate to respiratory rate (HR/RR) was also calculated. Recordings were obtained during acute wheezy episodes in 18 children of median age 31 months and follow-up recordings from 16 of the children were obtained when they were wheeze-free. For the acutely wheezy children, frequency analysis of the pleth waveform was within 10 breaths/min of clinical assessment in 25 of 29 recordings in 15 children. For the follow-up measurements, frequency analysis of the pleth waveform showed similarly good agreement in recordings on 15 of the 16 children. Respiratory rate was higher (p < 0.001), and HR/RR ratio was lower (p = 0.03) during acute wheeze than at follow-up. This study suggests that respiratory rate can be derived from pleth traces in wheezy preschool children.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9315E..03J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9315E..03J"><span><span class="hlt">Oximetry</span> system performance assessment with POM (acetal) phantoms incorporating hemoglobin calibration standards and customized saturation levels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jang, Hyounguk; Singh, Karam; Wang, Hsing-Wen; Pfefer, T. J.; Chen, Yu</p> <p>2015-03-01</p> <p>Standardized approaches for performance assessment of biophotonic devices have the potential to facilitate system development and intercomparison, clinical trial standardization, recalibration, manufacturing quality control and quality assurance during clinical use. Evaluation of devices based on near-infrared spectroscopy (NIRS) for detection of hemoglobin (Hb) content and oxygenation have often involved tissue-simulating phantoms incorporating artificial dyes or flow systems. Towards the development of simple, effective techniques for objective, quantitative evaluation of basic NIRS system performance, we have developed and evaluated two test methods. These methods are based on cuvette inserts in solid turbid phantoms for measuring commercially-available Hb <span class="hlt">oximetry</span> standards and custom-formulated oxy/deoxy-Hb solutions. Both approaches incorporate solid acetal, or polyoxymethylene (POM), as a tissue-simulating matrix material. First, inverse-adding-doubling (IAD) based on measurements with a spectrophotometer and an integrating sphere was used to measure POM optical properties and their stability over time. Second, two fiberopticprobe- based NIRS systems were used to measure concentration change of oxy- and deoxy-Hb in standard Hb solutions and customized Hb solutions by adding yeast. Differences in system performance were likely due to differences in light source outputs and fiberoptic probe design. Our preliminary results indicate that simple phantom-based approaches based on commercially available polymers and inclusions containing Hb standards, or controlled oxygenation levels may be useful for benchtop assessment of NIRS device quality for a variety of biophotonic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23866687','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23866687"><span>Feasibility of pulse <span class="hlt">oximetry</span> for assessment of infants born in community based midwifery care.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smit, Marrit; Ganzeboom, Angelina; Dawson, Jennifer A; Walther, Frans J; Bustraan, Jacqueline; van Roosmalen, Jos J M; te Pas, Arjan B</p> <p>2014-05-01</p> <p>to evaluate the feasibility of using pulse <span class="hlt">oximetry</span> (PO) for evaluating infants born in community-based midwifery care. a prospective, observational study of infants born after midwifery supervised (home) births. 27 midwives from seven practices providing primary care in (home) births used PO at birth or the early puerperal period over a ten-month period. Data were obtained on the effect of PO on outcome, interventions and decision-making. Midwives were surveyed about applicability and usefulness of PO. 153 infants born in primary midwifery care. all births were uncomplicated except for one infant receiving supplemental oxygen and another was mask ventilated. In 138/153 (90%) infants PO was successfully used and 88% of midwives found PO easy to use. In 148/153 (97%) infants PO did not influence midwives' clinical judgment and referral policy. In 5/153 (3%) infants, midwives were uncertain of the infant's condition, but PO measurements were reassuring. In case of suboptimal neonatal condition or resuscitation, 100% of midwives declared they would use PO again. it is feasible to use PO in community based midwifery care, but not considered an important contribution to routine evaluation of infants. Midwives would like to have PO available during suboptimal neonatal condition or when resuscitation is required. PO can be applied in community based midwifery care; it does not lead to insecurity or extra referral. Further research on a larger group of infants must show the effect of PO on neonatal outcomes. Copyright © 2013 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3832976','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3832976"><span><span class="hlt">Oximetry</span> Signal Processing Identifies REM Sleep-Related Vulnerability Trait in Asthmatic Children</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Perez, Geovanny F.; Gutierrez, Maria J.; Huseni, Shehlanoor; Pancham, Khrisna; Rodriguez-Martinez, Carlos E.; Nino, Cesar L.; Nino, Gustavo</p> <p>2013-01-01</p> <p>Rationale. The sleep-related factors that modulate the nocturnal worsening of asthma in children are poorly understood. This study addressed the hypothesis that asthmatic children have a REM sleep-related vulnerability trait that is independent of OSA. Methods. We conducted a retrospective cross-sectional analysis of pulse-<span class="hlt">oximetry</span> signals obtained during REM and NREM sleep in control and asthmatic children (n = 134). Asthma classification was based on preestablished clinical criteria. Multivariate linear regression model was built to control for potential confounders (significance level P ≤ 0.05). Results. Our data demonstrated that (1) baseline nocturnal respiratory parameters were not significantly different in asthmatic versus control children, (2) the maximal % of SaO2 desaturation during REM, but not during NREM, was significantly higher in asthmatic children, and (3) multivariate analysis revealed that the association between asthma and REM-related maximal % SaO2 desaturation was independent of demographic variables. Conclusion. These results demonstrate that children with asthma have a REM-related vulnerability trait that impacts oxygenation independently of OSA. Further research is needed to delineate the REM sleep neurobiological mechanisms that modulate the phenotypical expression of nocturnal asthma in children. PMID:24288619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24089256','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24089256"><span>Spectral dependence of absorption sensitivity on concentration of oxygenated hemoglobin: pulse <span class="hlt">oximetry</span> implications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strojnik, Marija; Paez, Gonzalo</p> <p>2013-10-01</p> <p>The sensitivity analysis indicates that the effective absorption coefficient is most sensitive to the concentration of oxygenated hemoglobin in spectral bands centered at 700 and 960 nm. We find that the highest temporal modulation due to heart function for a thick sample, like an arm, is at 940 nm, a significant shift from 710 nm measured for a finger. The most favorable spectral region for a thick transmission sample, such as a forearm, is the domain defined by intervals [900  nm ≤ λ₁ ≤ 1000  nm] and [650 nm ≤ λ₂ ≤ 720  nm]. We evaluated five near-infrared light-emitting diodes (LEDs) for their potential applications in <span class="hlt">oximetry</span>. The LED with peak emission at 930 nm emits well in this spectral region. Here the temporal noise is low, and the effective absorption coefficient is strongly dependent on the concentration of the oxygenated hemoglobin. High-quality saturation results are obtained through the forearm during a short measurement (30 s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=157270','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=157270"><span>Nitrate Effects on Nodule Oxygen Permeability and Leghemoglobin (Nodule <span class="hlt">Oximetry</span> and Computer Modeling).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Denison, R. F.; Harter, B. L.</p> <p>1995-01-01</p> <p>Two current hypotheses to explain nitrate inhibition of nodule function both involve decreased O2 supply for respiration in support of N2 fixation. This decrease could result from either (a) decreased O2 permeability (PO) of the nodule cortex, or (b) conversion of leghemoglobin (Lb) to an inactive, nitrosyl form. These hypotheses were tested using alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus) plants grown in growth pouches under controlled conditions. Nodulated roots were exposed to 10 mM KNO3 or KCI. Fractional oxygenation of Lb under air (FOLair), relative concentration of functional Lb, apparent PO, and O2-saturated central zone respiration rate were all monitored by nodule <span class="hlt">oximetry</span>. Apparent PO and FOLair in nitrate-treated nodules decreased to <50% of values for KCI controls within 24 h, but there was no decrease in functional Lb concentration during the first 72 h. In nitrate-treated alfalfa, but not in birdsfoot trefoil, FOLair, apparent PO, and O2-saturated central zone respiration rate decreased during each light period and recovered somewhat during the subsequent dark period. This species difference could be explained by greater reliance on photoreduction of nitrate in alfalfa than in birdsfoot trefoil. Computer simulations extended the experimental results, showing that previously reported decreases in apparent PO of Glycine max nodules with nitrate exposure cannot be explained by hypothetical decreases in the concentration or O2 affinity of Lb. PMID:12228439</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4819232','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4819232"><span>Evaluating Innovative In-Ear Pulse <span class="hlt">Oximetry</span> for Unobtrusive Cardiovascular and Pulmonary Monitoring During Sleep</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schiefer, Johannes; Blazek, Vladimir; Blanik, Nikolai; Leonhardt, Steffen</p> <p>2013-01-01</p> <p>Homecare is healthcare based on the principle “outpatient before inpatient,” with the aim of moving at least some care-delivery to the home. But reliable determination of vital signs at home requires new, smart sensors, which can be used by the patients themselves. We present a novel pulse <span class="hlt">oximetry</span> sensor worn in the ear channel. It was previously shown that measurement of heart rate, arterial oxygen saturation and related respiratory information can be performed with reliable accuracy under laboratory conditions. The present study explores the clinical feasibility of the sensor system for cardiovascular monitoring during sleep, with the aim to diagnose sleep apnea. For this, human trials were performed in a sleep laboratory including patients with a clinical suspicion of sleep apnea. Besides a general analysis of the sensor's signal quality during sleep, the evaluation focuses on heart rate dynamics and time-variant oxygen saturation. In addition, several methods to derive respiration rate from photoplethysmographic signals are examined and discussed. Results from the in-ear sensor are compared with standard polysomnography monitoring and demonstrate that this novel system allows long-term nocturnal measurement of heart rate, oxygen saturation and respiratory rate with sufficient accuracy. PMID:27170855</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19021395','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19021395"><span>Retinal vessel <span class="hlt">oximetry</span>-calibration, compensation for vessel diameter and fundus pigmentation, and reproducibility.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hammer, Martin; Vilser, Walthard; Riemer, Thomas; Schweitzer, Dietrich</p> <p>2008-01-01</p> <p>The purpose of this study was to measure the hemoglobin oxygenation in retinal vessels and to evaluate the sensitivity and reproducibility of the measurement. Using a fundus camera equipped with a special dual wavelength transmission filter and a color charge-coupled device camera, two monochromatic fundus images at 548 and 610 nm were recorded simultaneously. The optical densities of retinal vessels for both wavelengths and their ratio, which is known to be proportional to the oxygen saturation, were calculated. From 50-deg images, the used semiautomatic vessel recognition and tracking algorithm recognized and measured vessels of 100 microm or more in diameter. On average, arterial and venous oxygen saturations were measured at 98+/-10.1% and 65+/-11.7%, respectively. For measurements in the same vessel segments from the five images per subject, standard deviations of 2.52% and 3.25% oxygen saturation were found in arteries and veins, respectively. Respiration of 100% oxygen increased the mean arterial and venous oxygen saturation by 2% and 7% respectively. A simple system for noninvasive optical <span class="hlt">oximetry</span>, consisting of a special filter in a fundus camera and software, was introduced. It is able to measure the oxygen saturation in retinal branch vessels with reproducibility and sensitivity suitable for clinical investigations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4245..135S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4245..135S"><span>Minimizing the influence of fundus pigmentation on retinal vessel <span class="hlt">oximetry</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Matthew H.; Denninghoff, Kurt R.; Lompado, Arthur; Woodruff, Jacob B.; Hillman, Lloyd W.</p> <p>2001-06-01</p> <p>The goal of making calibrated oxygen saturation measurements of blood in retinal arteries and veins via a noninvasive spectroscopic technique has nearly been realized. Semi-continuous advancement in the field of retinal vessel <span class="hlt">oximetry</span> over the last three decades has resulted in several technologies that seem poised for commercialization. In this paper, we present our instrumentation and technique for making well-calibrated saturation measurements of the blood in retinal vessels. The Eye Oximeter (EOX) is a confocal scanning laser ophthalmoscope capable of acquiring multi-spectral images. Analysis of these spectral vessel images allows spectroscopic determination of the oxygen saturation of blood within each vessel. The primary emphasis of this paper is to illustrate the effect of fundus pigmentation on these oximetric measurements. We show that decreasing fundus reflectivity is mathematically similar to decreasing the vessel thickness. The apparent decreased vessel thickness is a direct consequence of scattering by red blood cells. We present in vitro and in vivo measurements that demonstrate an instrument calibration that is nearly independent of vessel diameter and fundus reflectivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27060375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27060375"><span>Preliminary investigation of multispectral retinal tissue <span class="hlt">oximetry</span> mapping using a hyperspectral retinal camera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Desjardins, Michèle; Sylvestre, Jean-Philippe; Jafari, Reza; Kulasekara, Susith; Rose, Kalpana; Trussart, Rachel; Arbour, Jean Daniel; Hudson, Chris; Lesage, Frédéric</p> <p>2016-05-01</p> <p><span class="hlt">Oximetry</span> measurement of principal retinal vessels represents a first step towards understanding retinal metabolism, but the technique could be significantly enhanced by spectral imaging of the fundus outside of main vessels. In this study, a recently developed Hyperspectral Retinal Camera was used to measure relative oximetric (SatO2) and total hemoglobin (HbT) maps of the retina, outside of large vessels, in healthy volunteers at baseline (N = 7) and during systemic hypoxia (N = 11), as well as in patients with glaucoma (N = 2). Images of the retina, on a field of view of ∼30°, were acquired between 500 and 600 nm with 2 and 5 nm steps, in under 3 s. The reflectance spectrum from each pixel was fitted to a model having oxy- and deoxyhemoglobin as the main absorbers and scattering modeled by a power law, yielding estimates of relative SatO2 and HbT over the fundus. Average optic nerve head (ONH) saturation over 8 eyes was 68 ± 5%. During systemic hypoxia, mean ONH saturation decreased by 12.5% on average. Upon further development and validation, the relative SatO2 and HbT maps of microvasculature obtained with this imaging system could ultimately contribute to the diagnostic and management of diseases affecting the ONH and retina.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037510','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037510"><span>Short baseline <span class="hlt">variations</span> in site response and <span class="hlt">wave</span>-propagation effects and their structural causes: Four examples in and around the santa clara valley, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hartzell, S.; Ramirez-Guzman, L.; Carver, D.; Liu, P.</p> <p>2010-01-01</p> <p>Ground motion records of local and regional events from a portable array are used to investigate the structural causes of <span class="hlt">variations</span> in ground motion over distances of a few hundred meters to a few kilometers in the sedimentary basin environment of the Santa Clara Valley, California, and its margins. Arrays of portable seismic stations are used to target four study areas with different ground motion patterns: (1) an edge of the alluvial basin extending up onto a marginal ridge (Blossom Hill), (2) a Cenozoic basin with a nearly flat bottom (Cupertino Basin), (3) a long, narrow Cenozoic basin with a steep V profile (Evergreen Basin), and (4) a line perpendicular to the trace of the Hayward fault. Average peak velocities on Blossom Hill from local earthquakes are a factor of 2.5 times higher than nearby valley sites. Three-dimensional (3D) modeling is used to conclude that the majority of the amplification is due to lower shear-<span class="hlt">wave</span> velocities along a local fault zone (Shannon–Berrocal). Site amplification over the Cupertino Basin in the frequency band 0.5–4 Hz is generally low (less than 2.0 relative to a Mesozoic rock site) and spatially uniform. This response is attributed to the shallow, flat-bottomed shape of the basin and the uniform, flat-laying sedimentary fill. In contrast, site amplification in the Evergreen Basin generally exceeds 3.0 and is attributed to the deep, V-shaped geometry of the basin and younger sedimentary fill. 3D waveform modeling shows the elongated shape of the Evergreen Basin causes more efficient trapping of long-period <span class="hlt">waves</span> for sources along the long axis of the basin. A low-velocity zone is postulated along the Hayward fault with a width between 100 and 200 m, based on elevated site response along the fault trace and 4.5-Hz fault zone guided <span class="hlt">waves</span> on the horizontal components of stations near the fault.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4331221','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4331221"><span>SWDreader: A Wavelet-Based Algorithm Using Spectral Phase to Characterize Spike-<span class="hlt">Wave</span> Morphological <span class="hlt">Variation</span> in Genetic Models of Absence Epilepsy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Richard, CD; Tanenbaum, A; Audit, B; Arneodo, A; Khalil, A; Frankel, WN</p> <p>2014-01-01</p> <p>Background Spike-<span class="hlt">wave</span> discharges (SWD) found in neuroelectrical recordings are pathognomonic to absence epilepsy. The characteristic spike-<span class="hlt">wave</span> morphology of the spike-<span class="hlt">wave</span> complex (SWC) constituents of SWDs can be mathematically described by a subset of possible spectral power and phase values. Morlet wavelet transform (MWT) generates time-frequency representations well-suited to identifying this SWC-associated subset. New method MWT decompositions of SWDs reveal spectral power concentrated at harmonic frequencies. The phase relationships underlying SWC morphology were identified by calculating the differences between phase values at SWD fundamental frequency and the 2nd, 3rd and 4th harmonics. The three phase differences were then used as coordinates to generate a density distribution in a {360° × 360° × 360°} phase difference space. Strain-specific density distributions were generated from SWDs of mice carrying the Gria4, Gabrg2 or Scn8a mutations to determine whether SWC morphological variants reliably mapped to the same regions of the distribution, and if distribution values could be used to detect SWD. Comparison with existing methods To the best of our knowledge, this algorithm is the first to employ spectral phase to quantify SWC morphology, making it possible to computationally distinguish SWC subtypes and detect SWDs. Results/conclusions Proof-of-concept testing of the SWDreader algorithm shows: (1) a major pattern of <span class="hlt">variation</span> in SWC morphology maps to one axis of the phase difference distribution, (2) variability between the strain-specific distributions reflects differences in the proportion of SWC subtypes generated during SWD, and (3) regularities in the spectral power and phase profiles of SWCs can be used to detect waveforms possessing SWC-like morphology. PMID:25549550</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdSpR..58..326G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdSpR..58..326G"><span>Modeling the <span class="hlt">variations</span> of reflection coefficient of Earth's lower ionosphere using very low frequency radio <span class="hlt">wave</span> data by artificial neural network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbari, Keyvan; Khakian Ghomi, Mehdi; Mohammadi, Mohammad; Marbouti, Marjan; Tan, Le Minh</p> <p>2016-08-01</p> <p>The ionized atmosphere lying from 50 to 600 km above surface, known as ionosphere, contains high amount of electrons and ions. Very Low Frequency (VLF) radio <span class="hlt">waves</span> with frequencies between 3 and 30 kHz are reflected from the lower ionosphere specifically D-region. A lot of applications in long range communications and navigation systems have been inspired by this characteristic of ionosphere. There are several factors which affect the ionization rate in this region, such as: time of day (presence of sun in the sky), solar zenith angle (seasons) and solar activities. Due to nonlinear response of ionospheric reflection coefficient to these factors, finding an accurate relation between these parameters and reflection coefficient is an arduous task. In order to model these kinds of nonlinear functionalities, some numerical methods are employed. One of these methods is artificial neural network (ANN). In this paper, the VLF radio <span class="hlt">wave</span> data of 4 sudden ionospheric disturbance (SID) stations are given to a multi-layer perceptron ANN in order to simulate the <span class="hlt">variations</span> of reflection coefficient of D region ionosphere. After training, validation and testing the ANN, outputs of ANN and observed values are plotted together for 2 random cases of each station. By evaluating the results using 2 parameters of pearson correlation coefficient and root mean square error, a satisfying agreement was found between ANN outputs and real observed data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4811501B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4811501B"><span>Observed longitude <span class="hlt">variations</span> of zonal wind, UV albedo and H2O at Venus cloud top level: the role of stationary gravity <span class="hlt">waves</span> generated by Venus topography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bertaux, Jean-Loup; Hauchecorne, Alain; khatuntsev, Igor; Markiewicz, Wojciech; Marcq, emmanuel; Lebonnois, Sebastien; Patsaeva, Marina; Turin, Alexander; Fedorova, Anna</p> <p>2016-10-01</p> <p>Based on the analysis of UV images (at 365 nm) of Venus cloud top (altitude 67±2 km) collected with VMC (Venus Monitoring Camera) on board Venus Express (VEX), it is found that the zonal wind speed south of the equator (from 5°S to 15°S) shows a conspicuous <span class="hlt">variation</span> (from -101 to -83 m/s) with geographic longitude of Venus, correlated with the underlying relief of Aphrodite Terra. We interpret this pattern as the result of stationary gravity <span class="hlt">waves</span> produced at ground level by the up lift of air when the horizontal wind encounters a mountain slope. These <span class="hlt">waves</span> can propagate up to the cloud top level, break there and transfer their momentum to the zonal flow. Such upward propagation of gravity <span class="hlt">waves</span> and influence on the wind speed vertical profile was shown to play an important role in the middle atmosphere of the Earth but is not reproduced in the current GCM of Venus atmosphere from LMD.In the equatorial regions, the UV albedo of clouds at 365 nm and the H2O mixing ratio at cloud top varies also with longitude, with an anti-correlation: the more H2O, the darker are the clouds. We argue that these <span class="hlt">variations</span> may be simply explained by the divergence of the horizontal wind field. In the longitude region (from 60° to -10°) where the horizontal wind speed is increasing in magnitude (stretch), it triggers air upwelling which brings both the UV absorber and H2O at cloud top level and decreases the albedo, and vice-versa when the wind is decreasing in magnitude (compression). This picture is fully consistent with the classical view of Venus meridional circulation, with upwelling at equator revealed by horizontal air motions away from equator: the longitude effect is only an additional but important modulation of this effect. We argue that H2O enhancement is the sign of upwelling because the H2O mixing ratio decreases with altitude, comforting the view that the UV absorber is also brought to cloud top by upwelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850066080&hterms=gas+laws&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgas%2Blaws','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850066080&hterms=gas+laws&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgas%2Blaws"><span>Application of TVD schemes for the Euler equations of gas dynamics. [method of Total <span class="hlt">Variation</span> Diminishing for shock <span class="hlt">wave</span> computation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yee, H. C.; Warming, R. F.; Harten, A.</p> <p>1985-01-01</p> <p>Highly accurate and yet stable shock-capturing finite difference schemes have been designed for the computation of the Euler equations of gas dynamics. Four different principles for the construction of high resolution total <span class="hlt">variation</span> diminishing (TVD) schemes are available, including hybrid schemes, a second-order extension of Godunov's scheme by van Leer (1979), the modified flux approach of Harten (1983, 1984), and the numerical fluctuation approach of Roe (1985). The present paper has the objective to review the class of second-order TVD schemes via the modified flux approach. Attention is given to first-order TVD schemes, a second-order accurate explicit TVD scheme, the global order of accuracy of the second-order TVD scheme, extensions to systems and two-dimensional conservation laws, numerical experiments with a second-order explicit TVD scheme, implicit TVD schemes, and second-order implicit TVD schemes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28043739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28043739"><span>Canadian Cardiovascular Society/Canadian Pediatric Cardiology Association Position Statement on Pulse <span class="hlt">Oximetry</span> Screening in Newborns to Enhance Detection of Critical Congenital Heart Disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wong, Kenny K; Fournier, Anne; Fruitman, Deborah S; Graves, Lisa; Human, Derek G; Narvey, Michael; Russell, Jennifer L</p> <p>2017-02-01</p> <p>Congenital heart disease is the most common congenital malformation and approximately 3 in 1000 newborns have critical congenital heart disease (CCHD). Timely diagnosis affects morbidity, mortality, and disability, and newborn pulse <span class="hlt">oximetry</span> screening has been studied to enhance detection of CCHD. In this position statement we present an evaluation of the literature for pulse <span class="hlt">oximetry</span> screening. Current detection strategies including prenatal ultrasound examination and newborn physical examination are limited by low diagnostic sensitivity. Pulse <span class="hlt">oximetry</span> screening is safe, noninvasive, easy to perform, and widely available with a high specificity (99.9%) and moderately high sensitivity (76.5%). When an abnormal saturation is obtained, the likelihood of having CCHD is 5.5 times greater than when a normal result is obtained. The use of pulse <span class="hlt">oximetry</span> combined with current strategies has shown sensitivities of up to 92% for detecting CCHD. False positive results can be minimized by screening after 24 hours, and testing the right hand and either foot might further increase sensitivity. Newborns with abnormal screening results should undergo a comprehensive assessment and echocardiography performed if a cardiac cause