A framework based on 2-D Taylor expansion for quantifying the impacts of subpixel reflectance variance and covariance on cloud optical thickness and effective radius retrievals based on the bispectral method

NASA Astrophysics Data System (ADS)

Zhang, Z.; Werner, F.; Cho, H.-M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, K.

2016-06-01

The bispectral method retrieves cloud optical thickness (τ) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VIS/NIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring subpixel variations of cloud reflectances can lead to a significant bias in the retrieved τ and re. In the literature, the retrievals of τ and re are often assumed to be independent and considered separately when investigating the impact of subpixel cloud reflectance variations on the bispectral method. As a result, the impact on τ is contributed only by the subpixel variation of VIS/NIR band reflectance and the impact on re only by the subpixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of subpixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the τ and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how subpixel cloud reflectance variations impact the τ and re retrievals based on the bispectral method. In particular, our framework provides a mathematical explanation of how the subpixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used to estimate the retrieval uncertainty from subpixel reflectance variations in operational satellite cloud products and to help understand the differences in τ and re retrievals between two instruments.

A Framework Based on 2-D Taylor Expansion for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method

NASA Technical Reports Server (NTRS)

Zhang, Z.; Werner, F.; Cho, H. -M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

2016-01-01

The bi-spectral method retrieves cloud optical thickness and cloud droplet effective radius simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VISNIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved and re. In the literature, the retrievals of and re are often assumed to be independent and considered separately when investigating the impact of sub-pixel cloud reflectance variations on the bi-spectral method. As a result, the impact on is contributed only by the sub-pixel variation of VISNIR band reflectance and the impact on re only by the sub-pixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VISNIR and SWIR cloud reflectances and their covariance on the and re retrievals. This framework takes into account the fact that the retrievals are determined by both VISNIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VISNIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used to estimate the retrieval uncertainty from sub-pixel reflectance variations in operational satellite cloud products and to help understand the differences in and re retrievals between two instruments.

A Framework Based on 2-D Taylor Expansion for Quantifying the Impacts of Subpixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bispectral Method

NASA Technical Reports Server (NTRS)

Zhang, Z.; Werner, F.; Cho, H.-M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, K.

2016-01-01

The bispectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VIS/NIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring subpixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In the literature, the retrievals of t and re are often assumed to be independent and considered separately when investigating the impact of subpixel cloud reflectance variations on the bispectral method. As a result, the impact on t is contributed only by the subpixel variation of VIS/NIR band reflectance and the impact on re only by the subpixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of subpixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how subpixel cloud reflectance variations impact the t and re retrievals based on the bispectral method. In particular, our framework provides a mathematical explanation of how the subpixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used to estimate the retrieval uncertainty from subpixel reflectance variations in operational satellite cloud products and to help understand the differences in t and re retrievals between two instruments.

Characterization of Sleep Using Bispectral Analysis

DTIC Science & Technology

2001-10-25

approved the Bispectral Index (BIS) - developed by Aspect Medical Systems (Natick, MA) - as a tool for monitoring the depth of anesthesia based on...on the brain [2]. The A-1000 BIS monitor quantifies the level of hypnosis based on frequency, amplitude, and coherence of the EEG. The BIS index...on a scale of 0-100 (100 reflecting the fully conscious or awake state), is a single-number indicator of the level of induced hypnosis . Furthermore

Bispectral index monitoring during electroconvulsive therapy under propofol anaesthesia.

PubMed

Gunawardane, P O; Murphy, P A; Sleigh, J W

2002-02-01

The accuracy of the bispectral index (BIS) as a monitor of consciousness has not been well studied in patients who have abnormal electroencephalograms (EEG). We studied the changes in BIS, its subparameters, and spectral entropy of the EEG during 18 electroconvulsive treatments under propofol and succinylcholine anaesthesia. A single bifrontal EEG, and second subocular channel (for eye movement estimation) was recorded. The median (interquartile range) BIS value at re-awakening was only 57 (47-78)--thus more than a quarter of the patients woke at BIS values of less than 50. The changes in spectral entropy values were similar: 0.84 (0.68-0.99) at the start, 0.65 (0.42-0.88) at the point of loss-of-consciousness, 0.63 (0.47-0.79) during the seizures, and 0.58 (0.31-0.85) at awakening. Post-ictal slow-wave activity in the EEG (acting via the SynchFastSlow subparameter) may cause low BIS values that do not correspond to the patient's clinical level of consciousness. This may be important in the interpretation of the BIS in other groups of patients who have increased delta-band power in their EEG.

Bispectral analysis: comparison of two windowing functions

NASA Astrophysics Data System (ADS)

Silvagni, D.; Djerroud, C.; Réveillé, T.; Gravier, E.

2018-02-01

Amongst all the normalized forms of bispectrum, the bicoherence is shown to be a very useful diagnostic tool in experimental studies of nonlinear wave interactions in plasma, as it measures the fraction of wave power due to the quadratic wave coupling in a self-excited fluctuation spectrum [1, 2]. In order to avoid spectral leakage, the application of a windowing function is needed during the bicoherence computation. Spectral leakage from statistically dependent components are of crucial importance in the discrimination between coupled and uncoupled modes, as they will introduce in the bicoherence spectrum phase-coupled modes which in reality do not exist. Therefore, the windowing function plays a key role in the bicoherence estimation. In this paper, two windowing methods are compared: the multiplication of the initial signal by the Hanning function and the subtraction of the straight line which links the two extremities of the signal. The influence of these two windowing methods on both the power spectrum and the bicoherence spectrum is showed. Although both methods give precise results, the Hanning function appears to be the more suitable window.

Update on bispectral index monitoring.

PubMed

Johansen, Jay W

2006-03-01

Since 1997, bispectral index (BIS; Aspect Medical Systems Inc., Natick, MA) has been in clinical practice and a wealth of experimental research has accumulated on its use. Originally, the device was approved only for monitoring hypnosis and has now received an indication for reducing the incidence of intraoperative awareness during anesthesia. Numerous studies have documented the ability of BIS to reduce intermediate outcomes such as hypnotic drug administration, extubation time, postoperative nausea and shortened recovery room discharge. Two recent large-scale outcome studies using BIS (one randomized controlled trial and one prospective, nonrandomized historical cohort study) identified an approximately 80% reduction in the incidence of recall after anesthesia. BIS provides clinicians with unique information that can be used to tailor hypnotic drug doses to individual patient requirements. BIS does not predict movement or hemodynamic response to stimulation, nor will it predict the exact moment consciousness returns. This review will also discuss other BIS applications including use in pediatrics, intensive care and for procedural sedation. Some limitations exist to the use of BIS and it is not useful for some individual hypnotic agents (ketamine, dexmedetomidine, nitrous oxide, xenon, opioids). BIS technology is moving out of the operating room and into diverse environments where conscious and deep sedation are provided. Anesthesiologists need to be actively involved in promoting patient safety and helping transition this technology into broader use.

The effect of lavender oil on stress, bispectral index values, and needle insertion pain in volunteers.

PubMed

Kim, Sioh; Kim, Hyun-Jae; Yeo, Jin-Seok; Hong, Sung-Jung; Lee, Ji-Min; Jeon, Younghoon

2011-09-01

The purpose of this study was to investigate whether lavender oil aromatherapy can reduce the bispectral index (BIS) values and stress and decrease the pain of needle insertion in 30 volunteers. Thirty (30) healthy volunteers were randomly allocated to 2 groups: the experimental group received oxygen with a face mask coated with lavender oil for 5 minutes, and the control group received oxygen through a face mask with no lavender oil for 5 minutes. The stress level (0=no stress, 10=maximum stress), BIS value, and pain intensity of needle insertion (0=no pain, 10=worst pain imaginable) were measured. There were no significant differences in age, sex, height, and weight between the two groups. Stress level, BIS value, and pain intensity of needle insertion before aromatherapy were similar between the two groups. However, the stress values (p<0.001) and BIS value (p<0.001) after aromatherapy were significantly reduced compared with the control. In addition, the pain intensity of needle insertion was significantly decreased after aromatherapy compared with the control (p<0.001). Lavender aromatherapy in volunteers provided a significant decrease in the stress levels and in the BIS values. In addition, it significantly reduced the pain intensity of needle insertion.

Comparison of Bispectral Index™ values during the flotation restricted environmental stimulation technique and results for stage I sleep: a prospective pilot investigation.

PubMed

Dunham, C Michael; McClain, Jesse V; Burger, Amanda

2017-11-29

To determine whether Bispectral Index™ values obtained during flotation-restricted environment stimulation technique have a similar profile in a single observation compared to literature-derived results found during sleep and other relaxation-induction interventions. Bispectral Index™ values were as follows: awake-state, 96.6; float session-1, 84.3; float session-2, 82.3; relaxation-induction, 82.8; stage I sleep, 86.0; stage II sleep, 66.2; and stages III-IV sleep, 45.1. Awake-state values differed from float session-1 (%difference 12.7%; Cohen's d = 3.6) and float session-2 (%difference 14.8%; Cohen's d = 4.6). Relaxation-induction values were similar to float session-1 (%difference 1.8%; Cohen's d = 0.3) and float session-2 (%difference 0.5%; Cohen's d = 0.1). Stage I sleep values were similar to float session-1 (%difference 1.9%; Cohen's d = 0.4) and float session-2 (%difference 4.3%; Cohen's d = 1.0). Stage II sleep values differed from float session-1 (%difference 21.5%; Cohen's d = 4.3) and float session-2 (%difference 19.6%; Cohen's d = 4.0). Stages III-IV sleep values differed from float session-1 (%difference 46.5%; Cohen's d = 5.6) and float session-2 (%difference 45.2%; Cohen's d = 5.4). Bispectral Index™ values during flotation were comparable to those found in stage I sleep and nadir values described with other relaxation-induction techniques.

Dreaming during anesthesia and anesthetic depth in elective surgery patients: a prospective cohort study.

PubMed

Leslie, Kate; Skrzypek, Hannah; Paech, Michael J; Kurowski, Irina; Whybrow, Tracey

2007-01-01

Dreaming reported after anesthesia remains a poorly understood phenomenon. Dreaming may be related to light anesthesia and represent near-miss awareness. However, few studies have assessed the relation between dreaming and depth of anesthesia, and their results were inconclusive. Therefore, the authors tested the hypothesis that dreaming during anesthesia is associated with light anesthesia, as evidenced by higher Bispectral Index values during maintenance of anesthesia. With approval, 300 consenting healthy patients, aged 18-50 yr, presenting for elective surgery requiring relaxant general anesthesia with a broad range of agents were studied. Patients were interviewed on emergence and 2-4 h postoperatively. The Bispectral Index was recorded from induction until the first interview. Dream content and form were also assessed. Dreaming was reported by 22% of patients on emergence. There was no difference between dreamers and nondreamers in median Bispectral Index values during maintenance (37 [23-55] vs. 38 [20-59]; P=0.68) or the time at Bispectral Index values greater than 60 (0 [0-7] vs. 0 [0-31] min; P=0.38). Dreamers tended to be younger and male, to have high home dream recall, to receive propofol maintenance or regional anesthesia, and to open their eyes sooner after surgery. Most dreams were similar to dreams of sleep and were pleasant, and the content was unrelated to surgery. Dreaming during anesthesia is unrelated to the depth of anesthesia in almost all cases. Similarities with dreams of sleep suggest that anesthetic dreaming occurs during recovery, when patients are sedated or in a physiologic sleep state.

Rational Ruijsenaars Schneider hierarchy and bispectral difference operators

NASA Astrophysics Data System (ADS)

Iliev, Plamen

2007-05-01

We show that a monic polynomial in a discrete variable n, with coefficients depending on time variables t1,t2,…, is a τ-function for the discrete Kadomtsev-Petviashvili hierarchy if and only if the motion of its zeros is governed by a hierarchy of Ruijsenaars-Schneider systems. These τ-functions were considered in [L. Haine, P. Iliev, Commutative rings of difference operators and an adelic flag manifold, Int. Math. Res. Not. 2000 (6) (2000) 281-323], where it was proved that they parametrize rank one solutions to a difference-differential version of the bispectral problem.

Bi-spectral index, entropy and predicted plasma propofol concentrations with target controlled infusions in Indian patients.

PubMed

Puri, Goverdhan D; Mathew, Preethy J; Sethu Madhavan, J; Hegde, Harihar V; Fiehn, Andreas

2011-10-01

Many processed electroencephalographic signals are used now to help the anaesthesiologist titrate the depth of sedation. We investigated the relationship between target plasma propofol concentration and objective end-points of sedation- Bispectral Index (BIS), State Entropy (SE) and Response Entropy (RE)-at clinical end-points as assessed by Modified Observer Assessment of Alertness/sedation Scale (MOAAS) in Indian patients. Eighteen ASA 1 and 2 Indian adult patients scheduled to undergo elective surgery were included. The target control infusion (TCI) of propofol was administered using 'Diprifusor'. The level of sedation was assessed using MOAAS by the anaesthesiologist. BIS, SE, RE were recorded throughout. TCI was started at 0.5 μg/ml and increased by 0.5 μg/ml every 6 min till MOAAS scores reached 0 or there was sustained BIS value less than 30. The EC(50) and EC(95) of predicted plasma propofol concentration for loss of consciousness (assessed by loss of response to verbal command), were 2.3 and 2.8 μg/ml respectively and for loss of response to painful stimuli (trapezius squeeze) were 4.0 and 5.0 μg/ml respectively. The BIS and entropy values (EC(50) and EC(95)) for loss of consciousness and response to painful stimuli in Indian patients were estimated. The preliminary relation of target plasma propofol concentration with BIS was found to be BIS = 100.5-16.4 × (Target concentration). The target plasma propofol concentrations required to produce unconsciousness and loss of response to painful stimuli in Indian patients have been estimated. Also, the relations between target plasma concentration and objective measures of different levels of anaesthesia have been established.

Bispectral pairwise interacting source analysis for identifying systems of cross-frequency interacting brain sources from electroencephalographic or magnetoencephalographic signals

NASA Astrophysics Data System (ADS)

Chella, Federico; Pizzella, Vittorio; Zappasodi, Filippo; Nolte, Guido; Marzetti, Laura

2016-05-01

Brain cognitive functions arise through the coordinated activity of several brain regions, which actually form complex dynamical systems operating at multiple frequencies. These systems often consist of interacting subsystems, whose characterization is of importance for a complete understanding of the brain interaction processes. To address this issue, we present a technique, namely the bispectral pairwise interacting source analysis (biPISA), for analyzing systems of cross-frequency interacting brain sources when multichannel electroencephalographic (EEG) or magnetoencephalographic (MEG) data are available. Specifically, the biPISA makes it possible to identify one or many subsystems of cross-frequency interacting sources by decomposing the antisymmetric components of the cross-bispectra between EEG or MEG signals, based on the assumption that interactions are pairwise. Thanks to the properties of the antisymmetric components of the cross-bispectra, biPISA is also robust to spurious interactions arising from mixing artifacts, i.e., volume conduction or field spread, which always affect EEG or MEG functional connectivity estimates. This method is an extension of the pairwise interacting source analysis (PISA), which was originally introduced for investigating interactions at the same frequency, to the study of cross-frequency interactions. The effectiveness of this approach is demonstrated in simulations for up to three interacting source pairs and for real MEG recordings of spontaneous brain activity. Simulations show that the performances of biPISA in estimating the phase difference between the interacting sources are affected by the increasing level of noise rather than by the number of the interacting subsystems. The analysis of real MEG data reveals an interaction between two pairs of sources of central mu and beta rhythms, localizing in the proximity of the left and right central sulci.

A Unified Point Process Probabilistic Framework to Assess Heartbeat Dynamics and Autonomic Cardiovascular Control

PubMed Central

Chen, Zhe; Purdon, Patrick L.; Brown, Emery N.; Barbieri, Riccardo

2012-01-01

In recent years, time-varying inhomogeneous point process models have been introduced for assessment of instantaneous heartbeat dynamics as well as specific cardiovascular control mechanisms and hemodynamics. Assessment of the model’s statistics is established through the Wiener-Volterra theory and a multivariate autoregressive (AR) structure. A variety of instantaneous cardiovascular metrics, such as heart rate (HR), heart rate variability (HRV), respiratory sinus arrhythmia (RSA), and baroreceptor-cardiac reflex (baroreflex) sensitivity (BRS), are derived within a parametric framework and instantaneously updated with adaptive and local maximum likelihood estimation algorithms. Inclusion of second-order non-linearities, with subsequent bispectral quantification in the frequency domain, further allows for definition of instantaneous metrics of non-linearity. We here present a comprehensive review of the devised methods as applied to experimental recordings from healthy subjects during propofol anesthesia. Collective results reveal interesting dynamic trends across the different pharmacological interventions operated within each anesthesia session, confirming the ability of the algorithm to track important changes in cardiorespiratory elicited interactions, and pointing at our mathematical approach as a promising monitoring tool for an accurate, non-invasive assessment in clinical practice. We also discuss the limitations and other alternative modeling strategies of our point process approach. PMID:22375120

Correlation of bispectral index (BIS) monitoring and end-tidal sevoflurane concentration in a patient with lobar holoprosencephaly.

PubMed

Galante, Dario; Fortarezza, Donatella; Caggiano, Maria; de Francisci, Giovanni; Pedrotti, Dino; Caruselli, Marco

2015-01-01

The bispectral index (BIS) is a parameter derived by electroencephalography (EEG) which provides a direct measurement of the effects of sedatives and anesthetics on the brain and offers guidance on the adequacy of anesthesia. The literature lacks studies on BIS monitoring in pediatric patients with congenital brain disease undergoing general anesthesia. A 13-year-old child weighing 32kg, suffering from lobar holoprosencephaly, underwent surgery in which the bispectral index (BIS) monitoring the depth of anesthesia showed an abnormal response. Detailed analysis of the trends of BIS values in the different observation times demonstrated sudden falls and repetitive values of BIS likely related to repetitive epileptiform electrical activity caused by sevoflurane. The BIS is a very useful monitoring tool for assessing the degree of depth of anesthesia and to analyze the electroencephalographic variations of anesthetics. Particular attention should be given to patients with congenital disorders of the central nervous system in which the BIS may give abnormal responses that do not reflect an accurate assessment of the depth of anesthesia. Copyright © 2014 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

[Correlation of bispectral index (BIS) monitoring and end-tidal sevoflurane concentration in a patient with lobar holoprosencephaly].

PubMed

Galante, Dario; Fortarezza, Donatella; Caggiano, Maria; de Francisci, Giovanni; Pedrotti, Dino; Caruselli, Marco

2015-01-01

The bispectral index (BIS) is a parameter derived by electroencephalography (EEG) which provides a direct measurement of the effects of sedatives and anesthetics on the brain and offers guidance on the adequacy of anesthesia. The literature lacks studies on BIS monitoring in pediatric patients with congenital brain disease undergoing general anesthesia. A 13-year-old child weighing 32kg, suffering from lobar holoprosencephaly, underwent surgery in which the bispectral index (BIS) monitoring the depth of anesthesia showed an abnormal response. Detailed analysis of the trends of BIS values in the different observation times demonstrated sudden falls and repetitive values of BIS likely related to repetitive epileptiform electrical activity caused by sevoflurane. The BIS is a very useful monitoring tool for assessing the degree of depth of anesthesia and to analyze the electroencephalographic variations of anesthetics. Particular attention should be given to patients with congenital disorders of the central nervous system in which the BIS may give abnormal responses that do not reflect an accurate assessment of the depth of anesthesia. Copyright © 2014 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Comparative study of Poincaré plot analysis using short electroencephalogram signals during anaesthesia with spectral edge frequency 95 and bispectral index.

PubMed

Hayashi, K; Yamada, T; Sawa, T

2015-03-01

The return or Poincaré plot is a non-linear analytical approach in a two-dimensional plane, where a timed signal is plotted against itself after a time delay. Its scatter pattern reflects the randomness and variability in the signals. Quantification of a Poincaré plot of the electroencephalogram has potential to determine anaesthesia depth. We quantified the degree of dispersion (i.e. standard deviation, SD) along the diagonal line of the electroencephalogram-Poincaré plot (named as SD1/SD2), and compared SD1/SD2 values with spectral edge frequency 95 (SEF95) and bispectral index values. The regression analysis showed a tight linear regression equation with a coefficient of determination (R(2) ) value of 0.904 (p < 0.0001) between the Poincaré index (SD1/SD2) and SEF95, and a moderate linear regression equation between SD1/SD2 and bispectral index (R(2)  = 0.346, p < 0.0001). Quantification of the Poincaré plot tightly correlates with SEF95, reflecting anaesthesia-dependent changes in electroencephalogram oscillation. © 2014 The Association of Anaesthetists of Great Britain and Ireland.

[Pneumocephalus as a cause of a decrease in the bispectral index].

PubMed

Herreras Gutiérrez, J L; Gilsanz Rodríguez, F

2014-01-01

A sharp decrease in the values of the bispectral index (BIS), along with an increase in suppression rate, was observed in a patient after the removal of an epidermoid tumor in the cerebellopontine angle by right retrosigmoid access under general anesthesia. This was probably related to a frontal pneumocephalus. No accompanying neurological signs were observed. The patient was extubated in the Recovery Room with no further incidents, as the BIS increased again. The neurosurgeons chose conservative treatment, relying on the reabsorption and redistribution of the air. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

A bispectral q-hypergeometric basis for a class of quantum integrable models

NASA Astrophysics Data System (ADS)

Baseilhac, Pascal; Martin, Xavier

2018-01-01

For the class of quantum integrable models generated from the q-Onsager algebra, a basis of bispectral multivariable q-orthogonal polynomials is exhibited. In the first part, it is shown that the multivariable Askey-Wilson polynomials with N variables and N + 3 parameters introduced by Gasper and Rahman [Dev. Math. 13, 209 (2005)] generate a family of infinite dimensional modules for the q-Onsager algebra, whose fundamental generators are realized in terms of the multivariable q-difference and difference operators proposed by Iliev [Trans. Am. Math. Soc. 363, 1577 (2011)]. Raising and lowering operators extending those of Sahi [SIGMA 3, 002 (2007)] are also constructed. In the second part, finite dimensional modules are constructed and studied for a certain class of parameters and if the N variables belong to a discrete support. In this case, the bispectral property finds a natural interpretation within the framework of tridiagonal pairs. In the third part, eigenfunctions of the q-Dolan-Grady hierarchy are considered in the polynomial basis. In particular, invariant subspaces are identified for certain conditions generalizing Nepomechie's relations. In the fourth part, the analysis is extended to the special case q = 1. This framework provides a q-hypergeometric formulation of quantum integrable models such as the open XXZ spin chain with generic integrable boundary conditions (q ≠ 1).

Toward More Accurate Iris Recognition Using Cross-Spectral Matching.

PubMed

Nalla, Pattabhi Ramaiah; Kumar, Ajay

2017-01-01

Iris recognition systems are increasingly deployed for large-scale applications such as national ID programs, which continue to acquire millions of iris images to establish identity among billions. However, with the availability of variety of iris sensors that are deployed for the iris imaging under different illumination/environment, significant performance degradation is expected while matching such iris images acquired under two different domains (either sensor-specific or wavelength-specific). This paper develops a domain adaptation framework to address this problem and introduces a new algorithm using Markov random fields model to significantly improve cross-domain iris recognition. The proposed domain adaptation framework based on the naive Bayes nearest neighbor classification uses a real-valued feature representation, which is capable of learning domain knowledge. Our approach to estimate corresponding visible iris patterns from the synthesis of iris patches in the near infrared iris images achieves outperforming results for the cross-spectral iris recognition. In this paper, a new class of bi-spectral iris recognition system that can simultaneously acquire visible and near infra-red images with pixel-to-pixel correspondences is proposed and evaluated. This paper presents experimental results from three publicly available databases; PolyU cross-spectral iris image database, IIITD CLI and UND database, and achieve outperforming results for the cross-sensor and cross-spectral iris matching.

Hypnosis is More Effective than Clinical Interviews.

PubMed

Almeida-Marques, Francisco Xavier De; Sánchez-Blanco, José; Cano-García, Francisco Javier

2018-01-01

To determine whether hypnosis is more effective than conventional interviewing to find traumatic life events in patients with fibromyalgia, we carried out a within-subject experimental design with complete intragroup counterbalancing. Thirty-two women under care in a public primary care center gave 2 identical interviews, with an interval of 3 months, in which the occurrence of traumatic life events was explored, once in a state of wakefulness and once in a state of hypnosis. The state of consciousness was evaluated using 3 measures: bispectral index, skin conductance level, and pain intensity. In the hypnotic state, the patients expressed 9.8 times more traumatic life events than in the waking state, a statistically significant difference with a large effect size.

The impact of age on bispectral index values and EEG bispectrum during anaesthesia with desflurane and halothane in children.

PubMed

Tirel, O; Wodey, E; Harris, R; Bansard, J Y; Ecoffey, C; Senhadji, L

2006-04-01

The relationship between end-tidal sevoflurane concentration, bispectral index (BIS) and the EEG bispectrum in children appears to be age dependent. The aim of this study was to quantify the BIS values at 1 MAC (minimum alveolar concentration) for desflurane and halothane, and explore the relationship with age for these anaesthetic agents in children. ECG, EEG and BIS were recorded continuously in 90 children aged 6-170 months requiring anaesthesia for elective surgery. Fifty children were anaesthetized with desflurane, and 40 children with halothane. Recordings were performed through to a steady state of 2 MAC, and thereafter at 1 and 0.5 MAC, respectively. The bispectrum of the EEG was estimated using MATLAB(c) software. A multiple correspondence analysis (MCA) was used. At a steady state of 1 MAC, BIS values were significantly higher with halothane 62 (43-80) than desflurane 34 (18-64). BIS values were significantly correlated with age in both groups: DES (r(2)=0.57; P<0.01) and HALO (r(2)=0.48; P<0.01). Changes in position in the structured model of the MCA (dependent on the pattern of the EEG bispectrum) were different for the two volatile anaesthetic agents. In children, BIS values are linked to age irrespective of the volatile anaesthetic agent used. The difference in BIS values for different agents at the same MAC can be explained by the specific effect on the EEG bispectrum induced by each anaesthetic agent, bringing into question the ability of the EEG bispectrum to accurately determine the depth of anaesthesia.

A marked decrease in bispectral index with elevation of suppression ratio by cervical haematoma reducing cerebral perfusion pressure.

PubMed

Umegaki, N; Hirota, K; Kitayama, M; Yatsu, Y; Ishihara, H; Mtasuki, A

2003-11-01

A 77-year-old man with a ruptured abdominal aortic aneurysm undergoing aneurysmectomy were anaesthetised with ketamine under bispectral index (BIS) monitoring, which is a clinical EEG monitor for measurement of depth of anaesthesia/sedation. First marked BIS reduction with elevation of suppression ratio (SR) was observed following severe hypotension by deflation of the aortic occlusion balloon. The re-inflation and rapid blood transfusion improved haemodyanamics and BIS and SR. At second marked BIS reduction with SR elevation, a heavy cervical swelling due to a massive subcutaneous haematoma around the previously mis-punctured right carotid artery extending throughout the whole neck was observed without hypotension. Cervical relief incision improved the BIS and SR. The present case suggests that BIS monitor may be a simple and convenient monitor for cerebral ischaemia detection.

A framework for quantifying the impacts of sub-pixel reflectance variance and covariance on cloud optical thickness and effective radius retrievals based on the bi-spectral method

NASA Astrophysics Data System (ADS)

Zhang, Z.; Werner, F.; Cho, H.-M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

2017-02-01

The so-called bi-spectral method retrieves cloud optical thickness (τ) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved τ and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the τ and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the τ and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

A Framework for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method.

NASA Technical Reports Server (NTRS)

Zhang, Z; Werner, F.; Cho, H. -M.; Wind, Galina; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

2017-01-01

The so-called bi-spectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the t and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

Utility of nociceptive flexion reflex threshold and bispectral index to predict movement responses under propofol anaesthesia.

PubMed

Jakuscheit, Axel; Posch, Matthias J; Gkaitatzis, Stefanos; Neumark, Lisa; Hackbarth, Mark; Schneider, Martin; Lichtner, Gregor; Baars, Jan H; von Dincklage, Falk

2017-06-01

The nociceptive flexion reflex threshold (NFRT) is a promising tool to monitor analgesia during general anaesthesia. Clinical studies have shown that the NFRT allows to predict movement responses to painful stimuli under a combined anaesthetic regime of sedative and opioid agents. Experimental studies indicated that the NFRT is also able to predict such movement responses under an exclusively sedative regime like propofol mono-anaesthesia. Therefore, we performed this study to investigate the ability of the NFRT to predict movement responses to painful stimuli in patients during a clinical propofol mono-anaesthesia. We investigated 140 cardiac surgery patients during their postoperative phase under propofol mono-anaesthesia. NFRT and bispectral index (BIS) were determined in each patient right before endotracheal suctioning or painful electrical test stimulation. Prediction probabilities were calculated to quantify how accurate each measure is able to predict movement responses to the stimuli. The 124 patients included in the analysis received a median propofol dosage of 3.2 (2.5-3.9) [median (IQR)] mg/kg/h. The included patients showed 287 movement responses after a total of 725 investigated stimuli. The prediction probabilities for positive movement responses were 0.63 (95%CI: 0.59-0.67) for the NFRT and 0.69 (95%CI: 0.65-0.73) for the BIS. The NFRT allows the prediction of movement responses under propofol mono-anaesthesia, which confirms its utility as a monitor to predict movement responses under general anaesthesia. The BIS allows an even more accurate prediction, although it does not reflect the physiological structures of movement suppression, but correlates closely with the dose of propofol. German clinical trial register (DRKS00003062, Deutsches Register Klinischer Studien).

The utility of bispectral index monitoring for prevention of rocuronium-induced withdrawal movement in children

PubMed Central

Lim, Byung Gun; Lee, Il Ok; Kim, Young Sung; Won, Young Ju; Kim, Heezoo; Kong, Myoung Hoon

2017-01-01

Abstract Background: This study was designed to determine whether a deep hypnotic state with a bispectral index (BIS) value less than 40 could alleviate withdrawal movement (WM) upon rocuronium injection during anesthesia induction in children. Methods: Finally, 135 healthy children (3–12 years) scheduled for minor elective surgery were studied. Without premedication, anesthesia was induced with thiopental sodium 5 mg/kg. Patients were randomized into 2 groups (control vs experimental) and then by virtue of rocuronium injection time, patients in the experimental group were allocated into 2 groups, as follows: in the control group (group C; n = 45), rocuronium 0.6 mg/kg was administered at the loss of eyelash reflex; in the 1st experimental group, rocuronium 0.6 mg/kg was administered when BIS fell to less than 40 (group T; n = 45); however, if BIS did not fall below 40 after thiopental sodium administration, manual ventilation was provided with oxygen 6 L/minute using sevoflurane 8% and then rocuronium was administered when BIS fell below 40 (the 2nd experimental group, group S; n = 45). Rocuronium-induced WM was evaluated using a 4-point scale (no movement; movement/withdrawal involving the arm only; generalized response, with movement/withdrawal of more than 1 extremity, but no requirement for restraint of the body; and generalized response which required restraint of the body and caused coughing or breath-holding). Results: No significant differences were found among the groups for patient characteristics including age, sex, height, and location of venous cannula. However, body weight, height, and body mass index in group S were all smaller than those in group T. The incidence of WM caused by rocuronium was 100% in group C, 95.6% in group T, and 80% in group S, and was significantly lower in group S than in group C. The grade of WM was 3.7 ± 0.6 in group C, 3.2 ± 0.9 in group T, and 2.6 ± 1.0 in group S. It was significantly lower in group T than in group C and significantly lower in group S than in groups C and T. Conclusion: The confirmation of a deep hypnotic state with BIS values lower than 40 using BIS monitoring can reduce the grade of rocuronium-induced WMs during anesthesia induction using thiopental sodium or sevoflurane in children. PMID:28079825

The utility of bispectral index monitoring for prevention of rocuronium-induced withdrawal movement in children: A randomized controlled trial.

PubMed

Lim, Byung Gun; Lee, Il Ok; Kim, Young Sung; Won, Young Ju; Kim, Heezoo; Kong, Myoung Hoon

2017-01-01

This study was designed to determine whether a deep hypnotic state with a bispectral index (BIS) value less than 40 could alleviate withdrawal movement (WM) upon rocuronium injection during anesthesia induction in children. Finally, 135 healthy children (3-12 years) scheduled for minor elective surgery were studied. Without premedication, anesthesia was induced with thiopental sodium 5 mg/kg. Patients were randomized into 2 groups (control vs experimental) and then by virtue of rocuronium injection time, patients in the experimental group were allocated into 2 groups, as follows: in the control group (group C; n = 45), rocuronium 0.6 mg/kg was administered at the loss of eyelash reflex; in the 1st experimental group, rocuronium 0.6 mg/kg was administered when BIS fell to less than 40 (group T; n = 45); however, if BIS did not fall below 40 after thiopental sodium administration, manual ventilation was provided with oxygen 6 L/minute using sevoflurane 8% and then rocuronium was administered when BIS fell below 40 (the 2nd experimental group, group S; n = 45). Rocuronium-induced WM was evaluated using a 4-point scale (no movement; movement/withdrawal involving the arm only; generalized response, with movement/withdrawal of more than 1 extremity, but no requirement for restraint of the body; and generalized response which required restraint of the body and caused coughing or breath-holding). No significant differences were found among the groups for patient characteristics including age, sex, height, and location of venous cannula. However, body weight, height, and body mass index in group S were all smaller than those in group T. The incidence of WM caused by rocuronium was 100% in group C, 95.6% in group T, and 80% in group S, and was significantly lower in group S than in group C. The grade of WM was 3.7 ± 0.6 in group C, 3.2 ± 0.9 in group T, and 2.6 ± 1.0 in group S. It was significantly lower in group T than in group C and significantly lower in group S than in groups C and T. The confirmation of a deep hypnotic state with BIS values lower than 40 using BIS monitoring can reduce the grade of rocuronium-induced WMs during anesthesia induction using thiopental sodium or sevoflurane in children.

Postoperative surveillance in neurosurgical patients - usefulness of neurological assessment scores and bispectral index.

PubMed

Herrero, Silvia; Carrero, Enrique; Valero, Ricard; Rios, Jose; Fábregas, Neus

We examined the additive effect of the Ramsay scale, Canadian Neurological Scale (CNS), Nursing Delirium Screening Scale (Nu-DESC), and Bispectral Index (BIS) to see whether along with the assessment of pupils and Glasgow Coma Scale (GCS) it improved early detection of postoperative neurological complications. We designed a prospective observational study of two elective neurosurgery groups of patients: craniotomies (CG) and non-craniotomies (NCG). We analyze the concordance and the odds ratio (OR) of altered neurological scales and BIS in the Post-Anesthesia Care Unit (PACU) for postoperative neurological complications. We compared the isolated assessment of pupils and GCS (pupils-GCS) with all the neurologic assessment scales and BIS (scales-BIS). In the CG (n=70), 16 patients (22.9%) had neurological complications in PACU. The scales-BIS registered more alterations than the pupils-GCS (31.4% vs. 20%; p<0.001), were more sensitive (94% vs. 50%) and allowed a more precise estimate for neurological complications in PACU (p=0.002; OR=7.15, 95% CI=2.1-24.7 vs. p=0.002; OR=9.5, 95% CI=2.3-39.4). In the NCG (n=46), there were no neurological complications in PACU. The scales-BIS showed alterations in 18 cases (39.1%) versus 1 (2.2%) with the pupils-GCS (p<0.001). Altered CNS on PACU admission increased the risk of neurological complications in the ward (p=0.048; OR=7.28, 95% CI=1.021-52.006). Applied together, the assessment of pupils, GCS, Ramsay scale, CNS, Nu-DESC and BIS improved early detection of postoperative neurological complications in PACU after elective craniotomies. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

[Postoperative surveillance in neurosurgical patients - usefulness of neurological assessment scores and bispectral index].

PubMed

Herrero, Silvia; Carrero, Enrique; Valero, Ricard; Rios, Jose; Fábregas, Neus

We examined the additive effect of the Ramsay scale, Canadian Neurological Scale (CNS), Nursing Delirium Screening Scale (Nu-DESC), and Bispectral Index (BIS) to see whether along with the assessment of pupils and Glasgow Coma Scale (GCS) it improved early detection of postoperative neurological complications. We designed a prospective observational study of two elective neurosurgery groups of patients: craniotomies (CG) and non-craniotomies (NCG). We analyze the concordance and the odds ratio (OR) of altered neurological scales and BIS in the Post-Anesthesia Care Unit (PACU) for postoperative neurological complications. We compared the isolated assessment of pupils and GCS (pupils-GCS) with all the neurologic assessment scales and BIS (scales-BIS). In the CG (n=70), 16 patients (22.9%) had neurological complications in PACU. The scales-BIS registered more alterations than the pupils-GCS (31.4% vs. 20%; p<0.001), were more sensitive (94% vs. 50%) and allowed a more precise estimate for neurological complications in PACU (p=0.002; OR=7.15, 95% CI=2.1-24.7 vs. p=0.002; OR=9.5, 95% CI=2.3-39.4). In the NCG (n=46), there were no neurological complications in PACU. The scales-BIS showed alterations in 18 cases (39.1%) versus 1 (2.2%) with the pupils-GCS (p<0.001). Altered CNS on PACU admission increased the risk of neurological complications in the ward (p=0.048; OR=7.28, 95% CI=1.021-52.006). Applied together, the assessment of pupils, GCS, Ramsay scale, CNS, Nu-DESC and BIS improved early detection of postoperative neurological complications in PACU after elective craniotomies. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Bispectral Index Monitoring: validity and utility in pediatric dentistry.

PubMed

Goyal, Ashima; Mittal, Neeti; Mittal, Parteek; Gauba, K

2014-01-01

Reliable and safe provision of sedation and general anesthesia is dependent on continuous vigilance of patient's sedation depth. Failure to do so may result in unintended oversedation or undersedation. It is a common practice to observe sedation depth by applying subjective sedation scales and in case of general anesthesia, practitioner is dependent on vital sign assessment. The Bispectral Index System (BIS) is a recently introduced objective, quantitative, easy to use, and free from observer bias, and clinically useful tool to assess sedation depth and it precludes the need to stimulate the patient to assess his sedation level. The present article is an attempt to orient the readers towards utility and validity of BIS for sedation and general anesthesia in pediatric dentistry. In this article, we attempt to make the readers understand the principle of BIS, its variation across sedation continuum, its validity across different age groups and for a variety of sedative drugs.

Bispectral analysis of equatorial spread F density irregularities

NASA Technical Reports Server (NTRS)

Labelle, J.; Lund, E. J.

1992-01-01

Bispectral analysis has been applied to density irregularities at frequencies 5-30 Hz observed with a sounding rocket launched from Peru in March 1983. Unlike the power spectrum, the bispectrum contains statistical information about the phase relations between the Fourier components which make up the waveform. In the case of spread F data from 475 km the 5-30 Hz portion of the spectrum displays overall enhanced bicoherence relative to that of the background instrumental noise and to that expected due to statistical considerations, implying that the observed f exp -2.5 power law spectrum has a significant non-Gaussian component. This is consistent with previous qualitative analyses. The bicoherence has also been calculated for simulated equatorial spread F density irregularities in approximately the same wavelength regime, and the resulting bispectrum has some features in common with that of the rocket data. The implications of this analysis for equatorial spread F are discussed, and some future investigations are suggested.

Seasonal Bias of Retrieved Ice Cloud Optical Properties Based on MISR and MODIS Measurements

NASA Astrophysics Data System (ADS)

Wang, Y.; Hioki, S.; Yang, P.; Di Girolamo, L.; Fu, D.

2017-12-01

The precise estimation of two important cloud optical and microphysical properties, cloud particle optical thickness and cloud particle effective radius, is fundamental in the study of radiative energy budget and hydrological cycle. In retrieving these two properties, an appropriate selection of ice particle surface roughness is important because it substantially affects the single-scattering properties. At present, using a predetermined ice particle shape without spatial and temporal variations is a common practice in satellite-based retrieval. This approach leads to substantial uncertainties in retrievals. The cloud radiances measured by each of the cameras of the Multi-angle Imaging SpectroRadiometer (MISR) instrument are used to estimate spherical albedo values at different scattering angles. By analyzing the directional distribution of estimated spherical albedo values, the degree of ice particle surface roughness is estimated. With an optimal degree of ice particle roughness, cloud optical thickness and effective radius are retrieved based on a bi-spectral shortwave technique in conjunction with two Moderate Resolution Imaging Spectroradiometer (MODIS) bands centered at 0.86 and 2.13 μm. The seasonal biases of retrieved cloud optical and microphysical properties, caused by the uncertainties in ice particle roughness, are investigated by using one year of MISR-MODIS fused data.

Comparison of dexmedetomidine and propofol used for drug-induced sleep endoscopy in patients with obstructive sleep apnea syndrome.

PubMed

Kuyrukluyıldız, Ufuk; Binici, Orhan; Onk, Didem; Ayhan Celik, Serap; Torun, Mumtaz Taner; Unver, Edhem; Ozcicek, Adalet; Alagol, Aysin

2015-01-01

Backround: Surgical operations are alternative treatments in persons with Obstructive Sleep Apnea Syndrome who cannot tolerate continuous positive airway pressure therapy. Drug-Induced Sleep Endoscopy is a method with which somnolence is pharmacologically induced and collapse is evaluated through nasal endoscopy in patients with Obstructive Sleep Apnea Syndrome. We aimed to evaluate efficiency of dexmedetomidine or propofol used for sedation in patients undergoing drug-induced sleep endoscopy. A total of 40 patients aged between 18 and 65 years old in the ASA STATUS I-II group were included in the study. After premedicatıon wıth midazolam 0.05 mg/kg intravenously, patients were randomly divided into two groups and administered intravenous (iv) propofol with the loading dose of 0.7 mg/kg for 10 minutes, followed 0.5 mg/kg/h infusion (Group P); or dexmedetomidine with the loading dose of 1 mcg/kg for 10 minutes, followed by 0.3 mcg/kg/h infusion (Group D). Haemodynamic and respiratuary parameters, Bispectral index score, Ramsey sedation score, time to achieve sufficient sedation, surgeon's and patients' satisfaction, postoperative Aldrete score and side effects were recorded. Time to achieve sufficient sedation, Bispectral index scores at 5, 10 and 15th. minutes intraoperatively, first Aldrete score in the recovery room, SpO2 values and respiratory rates all over the surgical procedure and in the recovery room were found lower in Group P (P<0.05). Bispectral index scores, mean arterial pressure and heart rate in the recovery room were significantly lower in Group D (P<0.05). Dexmedetomidine may be preferred as a safer agent with respecting to respiratory function compared with propofol in obstructive sleep apnea patients who known to be susceptible to hypoxia and hypercarbia.

Bispectral index to predict neurological outcome early after cardiac arrest.

PubMed

Stammet, Pascal; Collignon, Olivier; Werer, Christophe; Sertznig, Claude; Devaux, Yvan

2014-12-01

To address the value of continuous monitoring of bispectral index (BIS) to predict neurological outcome after cardiac arrest. In this prospective observational study in adult comatose patients treated by therapeutic hypothermia after cardiac arrest we measured bispectral index (BIS) during the first 24 hours of intensive care unit stay. A blinded neurological outcome assessment by cerebral performance category (CPC) was done 6 months after cardiac arrest. Forty-six patients (48%) had a good neurological outcome at 6-month, as defined by a cerebral performance category (CPC) 1-2, and 50 patients (52%) had a poor neurological outcome (CPC 3-5). Over the 24h of monitoring, mean BIS values over time were higher in the good outcome group (38 ± 9) compared to the poor outcome group (17 ± 12) (p<0.001). Analysis of BIS recorded every 30 minutes provided an optimal prediction after 12.5h, with an area under the receiver operating characteristic curve (AUC) of 0.89, a specificity of 89% and a sensitivity of 86% using a cut-off value of 23. With a specificity fixed at 100% (sensitivity 26%) the cut-off BIS value was 2.4 over the first 271 minutes. In multivariable analyses including clinical characteristics, mean BIS value over the first 12.5h was a predictor of neurological outcome (p = 6E-6) and provided a continuous net reclassification index of 1.28% (p = 4E-10) and an integrated discrimination improvement of 0.31 (p=1E-10). Mean BIS value calculated over the first 12.5h after ICU admission potentially predicts 6-months neurological outcome after cardiac arrest. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Comparative evaluation of polarimetric and bi-spectral cloud microphysics retrievals: Retrieval closure experiments and comparisons based on idealized and LES case studies

NASA Astrophysics Data System (ADS)

Miller, D. J.; Zhang, Z.; Ackerman, A. S.; Platnick, S. E.; Cornet, C.

2016-12-01

A remote sensing cloud retrieval simulator, created by coupling an LES cloud model with vector radiative transfer (RT) models is the ideal framework for assessing cloud remote sensing techniques. This simulator serves as a tool for understanding bi-spectral and polarimetric retrievals by comparing them directly to LES cloud properties (retrieval closure comparison) and for comparing the retrieval techniques to one another. Our simulator utilizes the DHARMA LES [Ackerman et al., 2004] with cloud properties based on marine boundary layer (MBL) clouds observed during the DYCOMS-II and ATEX field campaigns. The cloud reflectances are produced by the vectorized RT models based on polarized doubling adding and monte carlo techniques (PDA, MCPOL). Retrievals are performed utilizing techniques as similar as possible to those implemented on their corresponding well known instruments; polarimetric retrievals are based on techniques implemented for polarimeters (POLDER, AirMSPI, and RSP) and bi-spectral retrievals are performed using the Nakajima-King LUT method utilized on a number of spectral instruments (MODIS and VIIRS). Retrieval comparisons focus on cloud droplet effective radius (re), effective variance (ve), and cloud optical thickness (τ). This work explores the sensitivities of these two retrieval techniques to various observation limitations, such as spatial resolution/cloud inhomogeneity, impact of 3D radiative effects, and angular resolution requirements. With future remote sensing missions like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important to understand how these retrieval techniques compare to one another. The cloud retrieval simulator we've developed allows us to probe these important questions in a realistically relevant test bed.

Quantitative EEG correlations with brain glucose metabolic rate during anesthesia in volunteers.

PubMed

Alkire, M T

1998-08-01

To help elucidate the relationship between anesthetic-induced changes in the electroencephalogram (EEG) and the concurrent cerebral metabolic changes caused by anesthesia, positron emission tomography data of cerebral metabolism obtained in volunteers during anesthesia were correlated retrospectively with various concurrently measured EEG descriptors. Volunteers underwent functional brain imaging using the 18fluorodeoxyglucose technique; one scan always assessed awake-baseline cerebral metabolism (n = 7), and the other scans assessed metabolism during propofol sedation (n = 4), propofol anesthesia (n = 4), or isoflurane anesthesia (n = 5). The EEG was recorded continuously during metabolism assessment using a frontal-mastoid montage. Power spectrum variables, median frequency, 95% spectral edge, and bispectral index (BIS) values subsequently were correlated with the percentage of absolute cerebral metabolic reduction (PACMR) of glucose utilization caused by anesthesia. The percentage of absolute cerebral metabolic reduction, evident during anesthesia, trended median frequency (r = -0.46, P = 0.11), and the spectral edge (r = -0.52, P = 0.07), and correlated with anesthetic type (r = -0.70, P < 0.05), relative beta power (r = -0.60, P < 0.05), total power (r = 0.71,P < 0.01), and bispectral index (r = -0.81,P < 0.001). After controlling for anesthetic type, only bispectral index (r = 0.40, P = 0.08) and alpha power (r = 0.37, P = 0.10) approached significance for explaining residual percentage of absolute cerebral metabolic reduction prediction error. Some EEG descriptors correlated linearly with the magnitude of the cerebral metabolic reduction caused by propofol and isoflurane anesthesia. These data suggest that a physiologic link exists between the EEG and cerebral metabolism during anesthesia that is mathematically quantifiable.

A study to assess the value of bispectral analysis in intravenous sedation with midazolam during third molar surgery under local anaesthesia.

PubMed

Cheung, C W; Irwin, M G; Chiu, W K; Ying, C L A

2008-12-01

This study aimed to determine whether bispectral index (BIS) can be used as an indicator of sedation and recovery with intravenous midazolam. In Part A, 30 healthy patients undergoing third molar extraction under local anaesthesia were recruited. They were sedated with intravenous midazolam titrated to clinical endpoints. BIS values were recorded when adequately sedated (BIS(S)) and when clinical recovery criteria were met (BIS). In Part B, another 30 patients were sedated to the range of BIS(S) obtained in Part A. Recovery was assessed postoperatively when the range of BIS(R) from Part A was reached. BIS titrated patients required less midazolam (p < 0.001). Seventy percent of Part B patients required increments of midazolam during surgery, compared to 16.7% in Part A (p < 0.001). Total dose of midazolam given was lower in Part B (p = 0.025). BIS is not effective as a sole indicator of endpoint in sedation with intravenous midazolam.

Validation of the bispectral index as an indicator of anesthetic depth in Thoroughbred horses anesthetized with sevoflurane

PubMed Central

TOKUSHIGE, Hirotaka; KAKIZAKI, Masashi; ODE, Hirotaka; OKANO, Atsushi; OKADA, Jun; KURODA, Taisuke; WAKUNO, Ai; OHTA, Minoru

2016-01-01

ABSTRACT To evaluate the bispectral index (BIS) as an indicator of anesthetic depth in Thoroughbred horses, BIS values were measured at multiple stages of sevoflurane anesthesia in five horses anesthetized with guaifenesin and thiopental following premedication with xylazine. There was no significant difference between the BIS values recorded at end-tidal sevoflurane concentrations of 2.8% (median 60 ranging from 47 to 68) and 3.5% (median 71 ranging from 49 to 82) in anesthetized horses. These BIS values during anesthesia were significantly lower (P<0.01) than those in awake horses (median 98 ranging from 98 to 98) or sedated horses (median 92 ranging from 80 to 93). During the recovery phase, the BIS values gradually increased over time but did not significantly increase until the horses showed movement. In conclusion, the BIS value could be useful as an indicator of awakening during the recovery period in horses, as previous reported. PMID:27974877

Does patient position influence the reading of the bispectral index monitor?

PubMed

Kaki, Abdullah M; Almarakbi, Waleed A

2009-12-01

Bispectral index (BIS) was developed to monitor patients' level of consciousness under general anesthesia. Several factors have been found to alter BIS readings without affecting the depth of anesthesia. We conducted a study to assess the impact of changing patients' position on BIS readings. General anesthesia was administered to 40 patients undergoing minor surgeries. Patients were kept in neutral position (supine) for 15 min and BIS readings, mean arterial blood pressure, heart rate, end-tidal carbon dioxide, and end-tidal isoflurane were recorded. Patients were then shifted to head-down position (30 degrees), neutral position, and lastly head-up position (30 degrees) each of 15-min duration and the data were recorded. There was a significant increase in BIS values in head-down position (median 47 vs 40) compared with neutral position, whereas head-up position significantly decreased BIS (39 vs 41) compared with neutral position (P < 0.05). Changing a patient's position significantly affects the BIS values, which might affect the interpretation of anesthetic depth.

Cloud cover over the equatorial eastern Pacific derived from July 1983 International Satellite Cloud Climatology Project data using a hybrid bispectral threshold method

NASA Technical Reports Server (NTRS)

Minnis, Patrick; Harrison, Edwin F.; Gibson, Gary G.

1987-01-01

A set of visible and IR data obtained with GOES from July 17-31, 1983 is analyzed using a modified version of the hybrid bispectral threshold method developed by Minnis and Harrison (1984). This methodology can be divided into a set of procedures or optional techniques to determine the proper contaminate clear-sky temperature or IR threshold. The various optional techniques are described; the options are: standard, low-temperature limit, high-reflectance limit, low-reflectance limit, coldest pixel and thermal adjustment limit, IR-only low-cloud temperature limit, IR clear-sky limit, and IR overcast limit. Variations in the cloud parameters and the characteristics and diurnal cycles of trade cumulus and stratocumulus clouds over the eastern equatorial Pacific are examined. It is noted that the new method produces substantial changes in about one third of the cloud amount retrieval; and low cloud retrievals are affected most by the new constraints.

BIS-Guided Total Intravenous Anesthesia for Orchiopexy and Circumcision in a Child with Severe Autism: A Case Report

PubMed Central

Okur, Selçuk; Arıkan, Müge; Temel, Gülşen; Temel, Volkan

2012-01-01

Autistic children are very difficult to manage in the hospital setting because they react badly to any change in routine. We describe a case of 10-year-old male patient with severe autism undergoing orchidopexy and circumcision. Following premedication, anesthesia was induced with remifentanil, propofol, atracurium, and maintained with total intravenous anesthesia (propofol and remifentanil). The Bispectral Index System was monitored for determination of the depth of anesthesia. After surgery, all infusions were discontinued. The patient was then transferred to the postanesthetic care unit. There were no adverse events observed during the anesthetic management. The patient was discharged from the hospital on the second postoperative day. Bispectral Index System-guided Total Intravenous Anesthesia can provide some advantages for patient with autism, such as hemodynamic stability, early and easy recovery, to facilitate faster discharge, to optimize the delivery of anesthetic agents, to minimize its adverse effects, and to maximize its safety. PMID:23227368

Observation of beat oscillation generation by coupled waves associated with parametric decay during radio frequency wave heating of a spherical tokamak plasma.

PubMed

Nagashima, Yoshihiko; Oosako, Takuya; Takase, Yuichi; Ejiri, Akira; Watanabe, Osamu; Kobayashi, Hiroaki; Adachi, Yuuki; Tojo, Hiroshi; Yamaguchi, Takashi; Kurashina, Hiroki; Yamada, Kotaro; An, Byung Il; Kasahara, Hiroshi; Shimpo, Fujio; Kumazawa, Ryuhei; Hayashi, Hiroyuki; Matsuzawa, Haduki; Hiratsuka, Junichi; Hanashima, Kentaro; Kakuda, Hidetoshi; Sakamoto, Takuya; Wakatsuki, Takuma

2010-06-18

We present an observation of beat oscillation generation by coupled modes associated with parametric decay instability (PDI) during radio frequency (rf) wave heating experiments on the Tokyo Spherical Tokamak-2. Nearly identical PDI spectra, which are characterized by the coexistence of the rf pump wave, the lower-sideband wave, and the low-frequency oscillation in the ion-cyclotron range of frequency, are observed at various locations in the edge plasma. A bispectral power analysis was used to experimentally discriminate beat oscillation from the resonant mode for the first time. The pump and lower-sideband waves have resonant mode components, while the low-frequency oscillation is exclusively excited by nonlinear coupling of the pump and lower-sideband waves. Newly discovered nonlocal transport channels in spectral space and in real space via PDI are described.

Diurnal variability of regional cloud and clear-sky radiative parameters derived from GOES data. I - Analysis method. II - November 1978 cloud distributions. III - November 1978 radiative parameters

NASA Technical Reports Server (NTRS)

Minnis, P.; Harrison, E. F.

1984-01-01

Cloud cover is one of the most important variables affecting the earth radiation budget (ERB) and, ultimately, the global climate. The present investigation is concerned with several aspects of the effects of extended cloudiness, taking into account hourly visible and infrared data from the Geostationary Operational Environmental Satelite (GOES). A methodology called the hybrid bispectral threshold method is developed to extract regional cloud amounts at three levels in the atmosphere, effective cloud-top temperatures, clear-sky temperature and cloud and clear-sky visible reflectance characteristics from GOES data. The diurnal variations are examined in low, middle, high, and total cloudiness determined with this methodology for November 1978. The bulk, broadband radiative properties of the resultant cloud and clear-sky data are estimated to determine the possible effect of the diurnal variability of regional cloudiness on the interpretation of ERB measurements.

Hypnosis control based on the minimum concentration of anesthetic drug for maintaining appropriate hypnosis.

PubMed

Furutani, Eiko; Nishigaki, Yuki; Kanda, Chiaki; Takeda, Toshihiro; Shirakami, Gotaro

2013-01-01

This paper proposes a novel hypnosis control method using Auditory Evoked Potential Index (aepEX) as a hypnosis index. In order to avoid side effects of an anesthetic drug, it is desirable to reduce the amount of an anesthetic drug during surgery. For this purpose many studies of hypnosis control systems have been done. Most of them use Bispectral Index (BIS), another hypnosis index, but it has problems of dependence on anesthetic drugs and nonsmooth change near some particular values. On the other hand, aepEX has an ability of clear distinction between patient consciousness and unconsciousness and independence of anesthetic drugs. The control method proposed in this paper consists of two elements: estimating the minimum effect-site concentration for maintaining appropriate hypnosis and adjusting infusion rate of an anesthetic drug, propofol, using model predictive control. The minimum effect-site concentration is estimated utilizing the property of aepEX pharmacodynamics. The infusion rate of propofol is adjusted so that effect-site concentration of propofol may be kept near and always above the minimum effect-site concentration. Simulation results of hypnosis control using the proposed method show that the minimum concentration can be estimated appropriately and that the proposed control method can maintain hypnosis adequately and reduce the total infusion amount of propofol.

GOES Cloud Detection at the Global Hydrology and Climate Center

NASA Technical Reports Server (NTRS)

Laws, Kevin; Jedlovec, Gary J.; Arnold, James E. (Technical Monitor)

2002-01-01

The bi-spectral threshold (BTH) for cloud detection and height assignment is now operational at NASA's Global Hydrology and Climate Center (GHCC). This new approach is similar in principle to the bi-spectral spatial coherence (BSC) method with improvements made to produce a more robust cloud-filtering algorithm for nighttime cloud detection and subsequent 24-hour operational cloud top pressure assignment. The method capitalizes on cloud and surface emissivity differences from the GOES 3.9 and 10.7-micrometer channels to distinguish cloudy from clear pixels. Separate threshold values are determined for day and nighttime detection, and applied to a 20-day minimum composite difference image to better filter background effects and enhance differences in cloud properties. A cloud top pressure is assigned to each cloudy pixel by referencing the 10.7-micrometer channel temperature to a thermodynamic profile from a locally -run regional forecast model. This paper and supplemental poster will present an objective validation of nighttime cloud detection by the BTH approach in comparison with previous methods. The cloud top pressure will be evaluated by comparing to the NESDIS operational CO2 slicing approach.

Modeling and closed-loop control of hypnosis by means of bispectral index (BIS) with isoflurane.

PubMed

Gentilini, A; Rossoni-Gerosa, M; Frei, C W; Wymann, R; Morari, M; Zbinden, A M; Schnider, T W

2001-08-01

A model-based closed-loop control system is presented to regulate hypnosis with the volatile anesthetic isoflurane. Hypnosis is assessed by means of the bispectral index (BIS), a processed parameter derived from the electroencephalogram. Isoflurane is administered through a closed-circuit respiratory system. The model for control was identified on a population of 20 healthy volunteers. It consists of three parts: a model for the respiratory system, a pharmacokinetic model and a pharmacodynamic model to predict BIS at the effect compartment. A cascaded internal model controller is employed. The master controller compares the actual BIS and the reference value set by the anesthesiologist and provides expired isoflurane concentration references to the slave controller. The slave controller maneuvers the fresh gas anesthetic concentration entering the respiratory system. The controller is designed to adapt to different respiratory conditions. Anti-windup measures protect against performance degradation in the event of saturation of the input signal. Fault detection schemes in the controller cope with BIS and expired concentration measurement artifacts. The results of clinical studies on humans are presented.

Brain Monitoring with Electroencephalography and the Electroencephalogram-Derived Bispectral Index During Cardiac Surgery

PubMed Central

Kertai, Miklos D.; Whitlock, Elizabeth L.; Avidan, Michael S.

2011-01-01

Cardiac surgery presents particular challenges for the anesthesiologist. In addition to standard and advanced monitors typically used during cardiac surgery, anesthesiologists may consider monitoring the brain with raw or processed electroencephalography (EEG). There is strong evidence that a protocol incorporating the processed EEG Bispectral Index (BIS) decreases the incidence intraoperative awareness compared with standard practice. However there is conflicting evidence that incorporating the BIS into cardiac anesthesia practice improves “fast-tracking,” decreases anesthetic drug use, or detects cerebral ischemia. Recent research, including many cardiac surgical patients, shows that a protocol based on BIS monitoring is not superior to a protocol based on end tidal anesthetic concentration monitoring in preventing awareness. There has been a resurgence of interest in the anesthesia literature in limited montage EEG monitoring, including nonproprietary processed indices. This has been accompanied by research showing that with structured training, anesthesiologists can glean useful information from the raw EEG trace. In this review, we discuss both the hypothesized benefits and limitations of BIS and frontal channel EEG monitoring in the cardiac surgical population. PMID:22253267

Use of bispectral index system (BIS) to Monitor Enteral Conscious (moderate) sedation during general dental procedures.

PubMed

Donaldson, Mark; Goodchild, Jason H

2009-12-01

Although dental board regulations for the provision of in-office enteral conscious (oral) sedation vary widely with respect to training and pharmacologic strategies, they agree on the use of drugs that are inherently safe, the use of pulse oximetry and the availability of emergency equipment, including pharmacologic antagonists. Patient safety is of greatest concern and is best addressed by appropriate selection of patients, adequate training of personnel and appropriate monitoring of patients. Readings from bispectral index system (BIS) monitors, which use electroencephalographic signals, correlate accurately with depth of sedation during nondissociative general anesthesia of adults and children in the operating room setting. The usefulness of such monitoring as an adjunct to other forms of monitoring of in-office enteral sedation in the dental setting may represent the next important application of this tool, adding a further level of safety for the patient and another level of predictability for the practitioner. This paper reviews the current evidence supporting this new technique, presenting data from 20 procedures in which BIS monitoring during in-office enteral sedation was employed in a community dental practice.

Effect of relaxation on working memory and the Bispectral Index of the EEG.

PubMed

Hudetz, Judith A; Hudetz, Anthony G; Reddy, Diane M

2004-08-01

Beneficial effects of relaxation on cardiovascular and immune functions and on memory has been implied but an empirical relationship between task performance and anxiety reduction has not been reported. In this study, we investigated whether guided imagery of relatively short duration would decrease S-Anxiety and electroencephalogram Bispectral Index and improve working memory. 42 participants (age: M=39, SD=11, 14 men, 28 women, university students and VA Medical Center employees, recruited by their professor or by fellow employees) underwent relaxation by 16-min. guided imagery or no treatment (control). Spielberger's State-Trait Anxiety Inventory and the WAIS-III Letter-Number Sequencing Test were administered before and after relaxation. S-Anxiety and BIS Index decreased and the Letter-Number test score increased by 30% after relaxation but not in the control group. This score was higher for participants with low anxiety and BIS Index. There was no significant difference between the groups before treatment. The results suggest that guided imagery of short duration produces relaxation as measured by psychological and neurophysiological indices and improves working memory performance.

Comparison of dexmedetomidine and propofol used for drug-induced sleep endoscopy in patients with obstructive sleep apnea syndrome

PubMed Central

Kuyrukluyıldız, Ufuk; Binici, Orhan; Onk, Didem; Ayhan Celik, Serap; Torun, Mumtaz Taner; Unver, Edhem; Ozcicek, Adalet; Alagol, Aysin

2015-01-01

Backround: Surgical operations are alternative treatments in persons with Obstructive Sleep Apnea Syndrome who cannot tolerate continuous positive airway pressure therapy. Drug-Induced Sleep Endoscopy is a method with which somnolence is pharmacologically induced and collapse is evaluated through nasal endoscopy in patients with Obstructive Sleep Apnea Syndrome. Aims: We aimed to evaluate efficiency of dexmedetomidine or propofol used for sedation in patients undergoing drug-induced sleep endoscopy. Methods: A total of 40 patients aged between 18 and 65 years old in the ASA STATUS I-II group were included in the study. After premedicatıon wıth midazolam 0.05 mg/kg intravenously, patients were randomly divided into two groups and administered intravenous (iv) propofol with the loading dose of 0.7 mg/kg for 10 minutes, followed 0.5 mg/kg/h infusion (Group P); or dexmedetomidine with the loading dose of 1 mcg/kg for 10 minutes, followed by 0.3 mcg/kg/h infusion (Group D). Haemodynamic and respiratuary parameters, Bispectral index score, Ramsey sedation score, time to achieve sufficient sedation, surgeon’s and patients’ satisfaction, postoperative Aldrete score and side effects were recorded. Results: Time to achieve sufficient sedation, Bispectral index scores at 5, 10 and 15th. minutes intraoperatively, first Aldrete score in the recovery room, SpO2 values and respiratory rates all over the surgical procedure and in the recovery room were found lower in Group P (P<0.05). Bispectral index scores, mean arterial pressure and heart rate in the recovery room were significantly lower in Group D (P<0.05). Conclusion: Dexmedetomidine may be preferred as a safer agent with respecting to respiratory function compared with propofol in obstructive sleep apnea patients who known to be susceptible to hypoxia and hypercarbia. PMID:26131153

Effects of Hypothermic Cardiopulmonary Bypass on Internal Jugular Bulb Venous Oxygen Saturation, Cerebral Oxygen Saturation, and Bispectral Index in Pediatric Patients Undergoing Cardiac Surgery: A Prospective Study

PubMed Central

Hu, Zhiyong; Xu, Lili; Zhu, Zhirui; Seal, Robert; McQuillan, Patrick M.

2016-01-01

Abstract The objective of this study was to evaluate the effect of hypothermic cardiopulmonary bypass (CPB) on cerebral oxygen saturation (rSO2), internal jugular bulb venous oxygen saturation (SjvO2), mixed venous oxygen saturation (SvO2), and bispectral index (BIS) used to monitor cerebral oxygen balance in pediatric patients. Sixty American Society of Anesthesiologists Class II-III patients aged 1 to 4 years old with congenital heart disease scheduled for elective cardiac surgery were included in this study. Temperature, BIS, rSO2, mean arterial pressure, central venous pressure, cerebral perfusion pressure (CPP), and hematocrit were recorded. Internal jugular bulb venous oxygen saturation and SvO2 were obtained from blood gas analysis at the time points: after induction of anesthesia (T0), beginning of CPB (T1), ascending aortic occlusion (T2), 20 minutes after initiating CPB (T3), coronary reperfusion (T4), separation from CPB (T5), and at the end of operation (T6). The effect of hypothermia or changes in CPP on rSO2, SjvO2, SvO2, and BIS were analyzed. Compared with postinduction baseline values, rSO2 significantly decreased at all-time points: onset of extracorporeal circulation, ascending aortic occlusion, 20 minutes after CPB initiation, coronary reperfusion, and separation from CPB (P < 0.05). Compared with measurements made following induction of anesthesia, SjvO2 significantly increased with initiation of CPB, ascending aortic occlusion, 20 minutes after initiating CPB, coronary reperfusion, and separation from CPB (P < 0.05). Compared with induction of anesthesia, BIS significantly decreased with the onset of CPB, aortic cross clamping, 20 minutes after initiating CPB, and coronary reperfusion (P < 0.05). Bispectral index increased following separation from CPB. There was no significant change in SvO2 during cardiopulmonary bypass (P > 0.05). Correlation analysis demonstrated that rSO2 was positively related to CPP (r = 0.687, P = 0.000), with a low linear correlation to temperature (r = 0.453, P = 0.000). Internal jugular bulb venous oxygen saturation was negatively related to temperature (r = −0.689, P = 0.000). Bispectral index was positively related to both temperature (r = 0.824, P = 0.000) and CPP (r = 0.782, P = 0.000). Cerebral oxygen saturation had a positive linear correlation with CPP and a low linear correlation to temperature. Internal jugular bulb venous oxygen saturation had a negative linear correlation to temperature. Pre-and and early postbypass periods are vulnerable times for adequate cerebral oxygenation. Anesthetic management must aim to optimize the supply and demand relationship. PMID:26765454

Effects of Hypothermic Cardiopulmonary Bypass on Internal Jugular Bulb Venous Oxygen Saturation, Cerebral Oxygen Saturation, and Bispectral Index in Pediatric Patients Undergoing Cardiac Surgery: A Prospective Study.

PubMed

Hu, Zhiyong; Xu, Lili; Zhu, Zhirui; Seal, Robert; McQuillan, Patrick M

2016-01-01

The objective of this study was to evaluate the effect of hypothermic cardiopulmonary bypass (CPB) on cerebral oxygen saturation (rSO2), internal jugular bulb venous oxygen saturation (SjvO2), mixed venous oxygen saturation (SvO2), and bispectral index (BIS) used to monitor cerebral oxygen balance in pediatric patients.Sixty American Society of Anesthesiologists Class II-III patients aged 1 to 4 years old with congenital heart disease scheduled for elective cardiac surgery were included in this study. Temperature, BIS, rSO2, mean arterial pressure, central venous pressure, cerebral perfusion pressure (CPP), and hematocrit were recorded. Internal jugular bulb venous oxygen saturation and SvO2 were obtained from blood gas analysis at the time points: after induction of anesthesia (T0), beginning of CPB (T1), ascending aortic occlusion (T2), 20 minutes after initiating CPB (T3), coronary reperfusion (T4), separation from CPB (T5), and at the end of operation (T6). The effect of hypothermia or changes in CPP on rSO2, SjvO2, SvO2, and BIS were analyzed.Compared with postinduction baseline values, rSO2 significantly decreased at all-time points: onset of extracorporeal circulation, ascending aortic occlusion, 20 minutes after CPB initiation, coronary reperfusion, and separation from CPB (P < 0.05). Compared with measurements made following induction of anesthesia, SjvO2 significantly increased with initiation of CPB, ascending aortic occlusion, 20 minutes after initiating CPB, coronary reperfusion, and separation from CPB (P < 0.05). Compared with induction of anesthesia, BIS significantly decreased with the onset of CPB, aortic cross clamping, 20 minutes after initiating CPB, and coronary reperfusion (P < 0.05). Bispectral index increased following separation from CPB. There was no significant change in SvO2 during cardiopulmonary bypass (P > 0.05). Correlation analysis demonstrated that rSO2 was positively related to CPP (r = 0.687, P = 0.000), with a low linear correlation to temperature (r = 0.453, P = 0.000). Internal jugular bulb venous oxygen saturation was negatively related to temperature (r = -0.689, P = 0.000). Bispectral index was positively related to both temperature (r = 0.824, P = 0.000) and CPP (r = 0.782, P = 0.000). Cerebral oxygen saturation had a positive linear correlation with CPP and a low linear correlation to temperature. Internal jugular bulb venous oxygen saturation had a negative linear correlation to temperature.Pre-and and early postbypass periods are vulnerable times for adequate cerebral oxygenation. Anesthetic management must aim to optimize the supply and demand relationship.

Tonal noise of a controlled-diffusion airfoil at low angle of attack and Reynolds number.

PubMed

Padois, Thomas; Laffay, Paul; Idier, Alexandre; Moreau, Stéphane

2016-07-01

The acoustic signature of a controlled-diffusion airfoil immersed in a flow is experimentally characterized. Acoustic measurements have been carried out in an anechoic open-jet-wind-tunnel for low Reynolds numbers (from 5 × 10(4) to 4.3 × 10(5)) and several angles of attack. As with the NACA0012, the acoustic spectrum is dominated by discrete tones. These tonal behaviors are divided into three different regimes. The first one is characterized by a dominant primary tone which is steady over time, surrounded by secondary peaks. The second consists of two unsteady primary tones associated with secondary peaks and the third consists of a hump dominated by several small peaks. A wavelet study allows one to identify an amplitude modulation of the acoustic signal mainly for the unsteady tonal regime. This amplitude modulation is equal to the frequency interval between two successive tones. Finally, a bispectral analysis explains the presence of tones at higher frequencies.

Comparison of entropy and bispectral index during propofol and fentanyl sedation in monitored anaesthesia care.

PubMed

Balci, Canan; Karabekir, H S; Kahraman, F; Sivaci, R G

2009-01-01

Comparison of entropy (state entropy [SE] and response entropy [RE]) with the bispectral index (BIS) during propofol sedation in monitored anaesthesia care (MAC) was carried out in patients undergoing hand surgery. Thirty candidates for elective hand surgery were pre-medicated with midazolam 0.06 mg/kg and atropine 0.01 mg/kg. Sedation was induced with intravenous propofol and fentanyl was also administered. The Modified Observer's Assessment of Alertness/Sedation Scale (MOAA/S) was used to determine sedation level and pain was maintained at < 4 on a 0 - 10 verbal rating scale. The BIS, entropy, MOAA/S and pain values were recorded before initiation of sedation (control), during initiation of sedation, during surgery, and for 30 min after the end of surgery and anaesthesia. On initiation of sedation, entropy decreased more rapidly than BIS. At 10 min after initiation of sedation, the mean +/- SD values for MOAA/S, BIS, RE and SE were 3.00 +/- 0.36, 85.45 +/- 0.15, 74.00 +/- 0.60 and 72.02 +/- 0.12, respectively. During recovery, BIS and RE and SE increased in parallel with MOAA/S. It is concluded that entropy monitoring is as reliable as BIS monitoring in MAC.

Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths

NASA Astrophysics Data System (ADS)

Marcinkevics, Zbignevs; Rubins, Uldis; Zaharans, Janis; Miscuks, Aleksejs; Urtane, Evelina; Ozolina-Moll, Liga

2016-03-01

The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and the changes of perfusion index (PI) were obtained during the tests. The results showed convincing correlations for PI obtained by iPPG and LDI at (1) topical liniment (r=0.98) and (2) heating (r=0.98) tests. The topical liniment and local heating tests revealed good selectivity of the system for superficial microcirculation monitoring. It is confirmed that the iPPG system could be used for assessment of cutaneous perfusion at two different depths, morphologically and functionally different vascular networks, and thus utilized in clinics as a cost-effective alternative to the LDI.

Imaging photoplethysmography for clinical assessment of cutaneous microcirculation at two different depths.

PubMed

Marcinkevics, Zbignevs; Rubins, Uldis; Zaharans, Janis; Miscuks, Aleksejs; Urtane, Evelina; Ozolina-Moll, Liga

2016-03-01

The feasibility of bispectral imaging photoplethysmography (iPPG) system for clinical assessment of cutaneous microcirculation at two different depths is proposed. The iPPG system has been developed and evaluated for in vivo conditions during various tests: (1) topical application of vasodilatory liniment on the skin, (2) skin local heating, (3) arterial occlusion, and (4) regional anesthesia. The device has been validated by the measurements of a laser Doppler imager (LDI) as a reference. The hardware comprises four bispectral light sources (530 and 810 nm) for uniform illumination of skin, video camera, and the control unit for triggering of the system. The PPG signals were calculated and the changes of perfusion index (PI) were obtained during the tests. The results showed convincing correlations for PI obtained by iPPG530 nm and LDI at (1) topical liniment (r = 0.98) and (2) heating (r = 0.98) tests. The topical liniment and local heating tests revealed good selectivity of the system for superficial microcirculation monitoring. It is confirmed that the iPPG system could be used for assessment of cutaneous perfusion at two different depths, morphologically and functionally different vascular networks, and thus utilized in clinics as a cost-effective alternative to the LDI.

Anesthesia for arthroscopic shoulder surgery in the beach chair position: monitoring of cerebral oxygenation using combined bispectral index and near-infrared spectroscopy.

PubMed

Kawano, Hiroaki; Matsumoto, Tomomi

2014-10-01

Recent research has shown that cerebrovascular complications following shoulder surgery performed in the beach chair position under general anesthesia arise secondary to cerebral ischemia. Appropriate management of cerebral oxygenation is thus one of the primary goals of anesthetic management during such procedures. The present report describes the case of a 65-year-old male patient, in which both bispectral index (BIS) and near-infrared spectroscopy (NIRS) were used to monitor cerebral oxygenation. During the positioning, we observed an increased suppression ratio (SR) while BIS and regional cerebral oxygen saturation (rSO2) were at adequate level. In view of the difference in blood pressure between the heart and the base of the brain, blood pressure was maintained to ensure adequate cerebral perfusion. Although intraoperative rSO2 was at or around the cut-off point (a 12% relative decrease from baseline), no marked decrease in BIS or further increase in the SR was observed. Monitoring of cerebral perfusion using combined BIS and NIRS optimized anesthetic management during the performance of arthroscopic shoulder surgery in the beach chair position.

[Monitoring depth of anesthesia: a comparision between electroencephalographic nonlinear index and bispectral index].

PubMed

Yu, Hai; Yang, Xiao-Yun; Zhu, Da; Du, Run-Zi; Yin, Yan; Zhou, Rong-Hua; Liu, Bin

2010-01-01

To compare the efficiency and accuracy of electroencephalographic nonlinear index (ENI) and bispectral index (BIS) in monitoring depth of anesthesia during general anesthesia. Thirty patients undergoing elective abdominal surgery were recruited. The ability of ENI and BIS to distinguish between the anesthetic states (awake, loss of eyelash reflex, loss of response, steady anesthesia, first reaction and extubation) was analyzed with prediction probability (Pk). Correlation between ENI and BIS was tested by nonparametric Spearman rank correlation analysis, with data paired from awake through to extubation. The clinical performances of ENI and BIS were evaluated with success rate, responsiveness, and recovery time. ENI and BIS were better than mean arterial pressure (MAP) and heart rate (HR) for distinguishing between the states of anesthesia. ENI correlated strongly with BIS from the stage of awake through to extubation (r = 0.93). No differences were found between ENI and BIS in success rate and responsiveness; but the recovery time was shorter with ENI than with BIS. ENI and BIS provide similar information reflecting the states of anesthesia, which allows accurate distinguishment between different states of anesthesia. The clinical performance of ENI is better than that of BIS.

Effect of dexmedetomidine constant rate infusion on the bispectral index during alfaxalone anaesthesia in dogs.

PubMed

Navarrete, Rocio; Quirós-Carmona, Setefilla; Granados, María Del M; Gómez-Villamandos, Rafael J; Domínguez, Juan M; Férnandez-Sarmiento, José A; Muñoz-Rascón, Pilar; Funes, Francisco J; Morgaz, Juan

2016-07-01

To assess the effect of two rates of infusion of dexmedetomidine on the bispectral index (BIS) in dogs anaesthetized with alfaxalone constant rate infusion (CRI). Prospective, randomized, 'blinded' experimental study. Six healthy Beagles (three females and three males). Dogs received as premedication saline (group D0), 1 μg kg(-1) (group D1) or 2 μg kg(-1) (group D2) dexmedetomidine, intravenously (IV). Anaesthesia was induced with alfaxalone (6 mg kg(-1) to effect IV) and maintained with alfaxalone at 0.07 mg kg(-1)  minute(-1) and a CRI of saline (D0) or dexmedetomidine 0.5 μg kg(-1)  hour(-1) (D1) or 1 μg kg(-1)  hour(-1) (D2) for 90 minutes. BIS, electromyography (EMG), signal quality index (SQI) and suppression ratio (SR) were measured at 10 minute intervals and the median values were calculated. Nociceptive stimuli were applied every 30 minutes and BIS and cardiorespiratory values were compared before and after stimuli. Cardiorespiratory parameters were recorded throughout the study. BIS and EMG values differed significantly among groups, being lower in D2 (71 ± 8) than in D0 (85 ± 10) and D1 (84 ± 9). SQI was always over 90% and SR was zero throughout all the treatments. There were no significant differences between pre- and post-stimulus values of BIS, EMG and SQI for any treatment, although in D0 and D1, heart rate, respiratory rate and arterial pressures increased significantly after the nociceptive stimulus. Administration of dexmedetomidine (2 μg kg(-1)  + CRI 1 μg kg(-1)  hour(-1) ) decreases the BIS values and avoids the autonomic responses of a nociceptive stimulus during alfaxalone anaesthesia at 0.07 mg kg(-1)  minute(-1) in dogs. However, further studies are needed to verify whether this combination produces an adequate degree of hypnosis under surgical situations. © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Analysis Using Bi-Spectral Related Technique

DTIC Science & Technology

1993-11-17

filtering is employed as the data is processed (equation 1). Earlier results have shown that in contrast to the Wigner - Ville Distribution ( WVD ) no spectral...Technique by-o -~ Ralph Hippenstiel November 17, 1993 94 2 22 1 0 Approved for public reslease; distribution unlimited. Prepared for: Naval Command Control...Government. 12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION ’.ODE Approved for public relkase; distribution unlimited. 13. ABSTRACT (Maximum

Impact of a preoperative conversational hypnotic session on propofol consumption using closed-loop anesthetic induction guided by the bispectral index

PubMed Central

Bataille, Aurélien; Besset, Sébastien; Szekely, Barbara; Michel-Cherqui, Mireille; Dumans, Virginie; Liu, Ngai; Chazot, Thierry; Fischler, Marc; Le Guen, Morgan

2017-01-01

Abstract Objective: The automated administration of propofol in a closed loop could be used to objectively evaluate the nonpharmacological anesthetic action of hypnotherapy. The objective of this study was to evaluate the impact of a conversational hypnosis session on the consumption of propofol for anesthetic induction. Design: A randomized, usual care-controlled, single-center, patient-blind trial. Setting: Tertiary care center in France from November 2012 to December 2013. Participants: Adult patients scheduled for a surgical procedure under general anesthesia. Interventions: Before surgery, patients were randomized with a computer-generated random list for a preoperative conversational hypnosis session or for usual care. The conversational hypnosis session was conducted and individualized by the therapist with an academic degree in hypnosis in a quiet environment. Anesthetic induction was automatically performed by propofol without opioids and was assisted by the bispectral index in a closed loop. Outcome: Primary endpoint was the propofol dose required for anesthesia induction, defined as a Bispectral index less than 60 for at least 30 seconds. Results: The study included 48 patients in the hypnosis group and 49 patients in the control group. No difference in propofol consumption to obtain anesthesia induction was observed between the groups (total dose: 138.6 [67.5] and 130 [47.9] mg, P = .47; adjusted dose: 2.15 [1.09] and 1.95 [0.66] mg/kg, P = .28, for the hypnosis and control groups, respectively). Hetero-evaluation of arm movement during propofol injection (no reaction: 98% and 74%; P = .004, in the hypnosis and control groups, respectively) and face reaction at venous access placement (no reaction 59% and 30%; P = .017, in the hypnosis and control groups, respectively) were lower in the hypnosis group. No adverse event was reported. Conclusions: No difference in propofol consumption was observed in this study designed to evaluate the effect of a hypnotic conversational session on anesthesia induction using an automated tool for propofol administration. PMID:28489735

Relative Wave Energy based Adaptive Neuro-Fuzzy Inference System model for the Estimation of Depth of Anaesthesia.

PubMed

Benzy, V K; Jasmin, E A; Koshy, Rachel Cherian; Amal, Frank; Indiradevi, K P

2018-01-01

The advancement in medical research and intelligent modeling techniques has lead to the developments in anaesthesia management. The present study is targeted to estimate the depth of anaesthesia using cognitive signal processing and intelligent modeling techniques. The neurophysiological signal that reflects cognitive state of anaesthetic drugs is the electroencephalogram signal. The information available on electroencephalogram signals during anaesthesia are drawn by extracting relative wave energy features from the anaesthetic electroencephalogram signals. Discrete wavelet transform is used to decomposes the electroencephalogram signals into four levels and then relative wave energy is computed from approximate and detail coefficients of sub-band signals. Relative wave energy is extracted to find out the degree of importance of different electroencephalogram frequency bands associated with different anaesthetic phases awake, induction, maintenance and recovery. The Kruskal-Wallis statistical test is applied on the relative wave energy features to check the discriminating capability of relative wave energy features as awake, light anaesthesia, moderate anaesthesia and deep anaesthesia. A novel depth of anaesthesia index is generated by implementing a Adaptive neuro-fuzzy inference system based fuzzy c-means clustering algorithm which uses relative wave energy features as inputs. Finally, the generated depth of anaesthesia index is compared with a commercially available depth of anaesthesia monitor Bispectral index.

Use of BIS VISTA bilateral monitor for diagnosis of intraoperative seizures, a case report.

PubMed

Iturri Clavero, F; Tamayo Medel, G; de Orte Sancho, K; González Uriarte, A; Iglesias Martínez, A; Martínez Ruíz, A

2015-12-01

Changes in BIS (bispectral index) VISTA bilateral monitoring system associated with intraoperative episodes of generalized and focal seizures, during total intravenous anesthesia for resection of a left frontal parasagittal meningioma, are herein described. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Some characteristics of the three-dimensional structure of Santa Ana winds

Treesearch

Michael A. Fosberg; Clyde A. O' Dell; Mark J. Schroeder

1966-01-01

The three-dimensional structure of the Santa Ana was investigated in two case studies. Incorporated into a descriptive model of the Santa Ana were: (a) a bispectral gravity wave flow with a lee trough, produced by conservation of potential vorticity having a wave length of the order of 300 km. and short waves 6 to 10 km. long; (b) intensity of the foehn related to the...

Internal Tide Generation by Steep Topography

DTIC Science & Technology

2007-09-01

acting on the barotropic tide ( Foda and Hill 1998) was incomplete. Kunze will put this work in the context of recent internal tide research and...Topographically generated internal waves in the open ocean. J. Geophys. Res., 80, 320-327. Foda , M.A., and D.F. Hill, 1998: Nonlinear energy...Bispectral analysis of energy transfer within the two-dimensional ocean internal wave field. . Phys. Oceanogr., 35, 2104-2109. Garrett, C., and E

Ephedrine, but not phenylephrine, increases bispectral index values during combined general and epidural anesthesia.

PubMed

Ishiyama, Tadahiko; Oguchi, Takeshi; Iijima, Tetsuya; Matsukawa, Takashi; Kashimoto, Satoshi; Kumazawa, Teruo

2003-09-01

Ephedrine and phenylephrine are used to treat hypotension during combined general and epidural anesthesia, and they may change anesthetic depth. In the current study, we evaluated the effects of ephedrine versus phenylephrine on bispectral index (BIS) during combined general and epidural anesthesia. After injection of ropivacaine through the epidural catheter, general anesthesia was induced with propofol and vecuronium, and was maintained with 0.75% sevoflurane. Approximately 10 min after the intubation, BIS was recorded as a baseline value. Patients with decreases in arterial blood pressure <30% of the preanesthetic values were defined as control group (n = 9). Patients who had to be treated for larger decreases in arterial blood pressure were randomly assigned to receive ephedrine 0.1 mg/kg (n = 17) or phenylephrine 2 micro g/kg (n = 17). BIS values were recorded at 1-min intervals for 10 min. BIS in the ephedrine group was significantly larger from 7 to 10 min than that in the control and phenylephrine groups (P < 0.05). Seven patients in the ephedrine group had BIS >60, whereas no patient in the control and phenylephrine groups had BIS >60 (P < 0.005). Ephedrine, but not phenylephrine, increased BIS during general anesthesia combined with epidural anesthesia.

Comparison of equi-minimum alveolar concentration of sevoflurane and isoflurane on bispectral index values during both wash in and wash out phases: A prospective randomised study

PubMed Central

Gupta, Madhu; Shri, Iti; Sakia, Prashant; Govil, Deepika

2015-01-01

Background and Aims: At equal minimum alveolar concentration (MAC), volatile agents may produce different bispectral index (BIS) values especially at low BIS levels when the effect is volatile agent specific. The present study was performed to compare the BIS values produced by sevoflurane and isoflurane at equal MAC and thereby assessing which is a better hypnotic agent. Methods: Sixty American Society of Anaesthesiologists I and II patients undergoing elective mastoidectomy were divided into groups receiving either isoflurane or sevoflurane, and at equi-MAC. BIS value was measured during both wash in and wash out phase, keeping other parameters same. Statistical analysis was performed using the Friedman two-way analysis and Mann-Whitney U-test. A P < 0.05 was considered significant. Results: BIS value was significantly lower with sevoflurane at all MAC values as compared to isoflurane, except in the beginning and at MAC awake. However, both the drugs proved to be cardiostable. Conclusion: At equi-MAC sevoflurane produces lower BIS values during wash in as well as wash out phase as compared to isoflurane, reflecting probably an agent specific effect and a deficiency in BIS algorithm for certain agents and their interplay. PMID:25788739

A Study of Precipitation Occurrence Using Visual and Infrared Satellite Data.

DTIC Science & Technology

1983-12-01

THESIS A STUDY OF PRECIPITATION OCCURRENCE USING VISUAL AND INFRARED SATELLITE DATA by Linda Sue Paul December 1983 L1J Thesis Advisor: C . H. Wash Approved...PRECIPITATION SPECIFICATION ............ 18 A. INTRODUCTICI O N ...... • ........ 18 B. BI-SPECTRAL AND INFRARID THRBSH3LD ...... 18 C . LIFE HISTORY 3...4 III. DATA PROCESSING * .• ....... * ...... 󈧮 A. INTRODUCTION o . . . . . .o. . . o o . o 2 B. C ATA SORT o . o . . o o

Evaluation of Wireless Vital Signs Monitor in Trauma Patients

DTIC Science & Technology

2014-06-01

p=NS These data show that the R wave detection and pulse oximeter in the MWVSM finger probe are more accurate and follow changes better than those... oximeter signal failed to register with the thready pulse characteristic of hemorrhagic shock. This observation suggests that using a forehead and...would be more useful to measure from the forehead (e.g. near infrared spectroscopy (NIRS) or Bispectral EEG (BIS)) or extremity? 2) Does pulse

Bi-Spectral Method for Radar Target Recognition

DTIC Science & Technology

2006-12-01

θazimuth=60° and ϕelevation=30° with HV Polarization....................................53 Figure 50 Comparison of Radar Range Profile with Actual...radar systems. A comparison of the NCTR techniques and their relative advantages and disadvantages in target recognition performance is presented. 8...32 f fR i R R c c f fi R R i R R c c A e A e A e ψ ψ π ψ ψ π ψ ψ π ψ ψ

Bispectral Inversion: The Construction of a Time Series from Its Bispectrum

DTIC Science & Technology

1988-04-13

take the inverse transform . Since the goal is to compute a time series given its bispectrum, it would also be nice to stay entirely in the frequency...domain and be able to go directly from the bispectrum to the Fourier transform of the time series without the need to inverse transform continuous...the picture. The approximations arise from representing the bicovariance, which is the inverse transform of a continuous function, by the inverse disrte

Influence of hypobaric hypoxia on bispectral index and spectral entropy in volunteers.

PubMed

Ikeda, T; Yamada, S; Imada, T; Matsuda, H; Kazama, T

2009-08-01

Hypoxia has been shown to change electroencephalogram parameters including frequency and amplitude, and may thus change bispectral index (BIS) and spectral entropy values. If hypoxia per se changes BIS and spectral entropy values, BIS and spectral entropy values may not correctly reflect the depth of anaesthesia during hypoxia. The aim of this study was to examine the changes in BIS and spectral entropy values during hypobaric hypoxia in volunteers. The study was conducted in a high-altitude chamber with 11 volunteers. After the subjects breathed 100% oxygen for 15 min at the ground level, the simulated altitude increased gradually to the 7620 m (25,000 ft) level while the subjects continued to breathe oxygen. Then, the subjects discontinued to breath oxygen and breathed room air at the 7620 m level for up to 5 min until they requested to stop hypoxic exposure. Oxygen saturation (SpO2), heart rate, 95% spectral edge frequency (SEF), BIS, response entropy (RE), and state entropy (SE) of spectral entropy were recorded throughout the study period. Of the 11 subjects, seven subjects who underwent hypoxic exposure for 4 min were analysed. SpO2 decreased to 69% at the 7620 m level without oxygen. However, SEF, BIS, RE, and SE before and during hypoxic exposure were almost identical. These data suggest that hypoxia of oxygen saturation around 70% does not have a strong effect on BIS and spectral entropy.

Influence of dexmedetomidine on cognitive function in volunteers.

PubMed

Yatabe, Tomoaki; Tamura, Takahiko; Yamashita, Koichi; Yokoyama, Masataka

2016-09-01

Some outpatient procedures are performed under sedation with dexmedetomidine, although the effect of dexmedetomidine on cognitive function remains unclear. This study investigated the effect of dexmedetomidine on cognitive function in healthy volunteers. Observation study in volunteers. University-affiliated teaching hospital. Six healthy volunteers. After infusion of a 6-μg/kg per hour loading dose of dexmedetomidine for 10 minutes, a maintenance infusion of 0.4 μg/kg per hour was administered for 4 hours. Cognitive function was evaluated before infusion (baseline) and at 2, 4, 6, and 8 hours after infusion. Cognitive function, response speed, accuracy, and consistency were measured by CogHealth. Depth of sedation was evaluated at 1-hour intervals by evaluating the Bispectral Index. Data are presented as the change from baseline. The Bispectral Index value was significantly lower from 10 minutes to 6 hours after infusion versus the pre-infusion value. Response speed was also significantly lower at 2 hours and 4 hours after infusion (92 ± 8%, P< .0001; 93 ± 6%, P< .0001), as was consistency (96 ± 7%, P= .0009; 96 ± 5%, P= .0003). Response accuracy was unaltered by the infusion. Dexmedetomidine slightly reduced response speed and consistency, but did not affect response accuracy. Cognitive function was restored to pre-administration values 2 hours after the infusion of dexmedetomidine was discontinued. Copyright © 2016 Elsevier Inc. All rights reserved.

Individual reactions to viewing preferred video representations of the natural environment: A comparison of mental and physical reactions.

PubMed

Tsutsumi, Masae; Nogaki, Hiroshi; Shimizu, Yoshihisa; Stone, Teresa Elizabeth; Kobayashi, Toshio

2017-01-01

Globally, awareness of the vital link between health and the natural environment is growing. This pilot study, based on the idea of "forest bathing," or shinrin-yoku, the mindful use of all five senses to engage with nature in a natural environment, was initiated in order to determine whether stimulation by viewing an individual's preferred video of sea or forest had an effect on relaxation. The participants were 12 healthy men in their twenties and they were divided into two groups based on their preference for sea or forest scenery by using the Visual Analogue Scale. The participants watched 90 min DVDs of sea with natural sounds and forest with natural sounds while their heart rate variability and Bispectral Index System value were measured by using MemCalc/Tawara and a Bispectral Index System monitor. The participants were divided into two groups of six based on their preference for sea or forest scenery and each indicator was compared between them. Significant differences in a decrease in heart rate, increase in high frequency, and sustained arousal level were observed while viewing the preferred video. These results indicated that the viewing individual's preferred video of sea or forest had a relaxation effect. This study suggests that individual preferences should be taken into consideration for video relaxation therapy. © 2016 Japan Academy of Nursing Science.

Fuzzy control for closed-loop, patient-specific hypnosis in intraoperative patients: a simulation study.

PubMed

Moore, Brett L; Pyeatt, Larry D; Doufas, Anthony G

2009-01-01

Research has demonstrated the efficacy of closed-loop control of anesthesia using bispectral index (BIS) as the controlled variable, and the recent development of model-based, patient-adaptive systems has considerably improved anesthetic control. To further explore the use of model-based control in anesthesia, we investigated the application of fuzzy control in the delivery of patient-specific propofol-induced hypnosis. In simulated intraoperative patients, the fuzzy controller demonstrated clinically acceptable performance, suggesting that further study is warranted.

Pixelated coatings and advanced IR coatings

NASA Astrophysics Data System (ADS)

Pradal, Fabien; Portier, Benjamin; Oussalah, Meihdi; Leplan, Hervé

2017-09-01

Reosc developed pixelated infrared coatings on detector. Reosc manufactured thick pixelated multilayer stacks on IR-focal plane arrays for bi-spectral imaging systems, demonstrating high filter performance, low crosstalk, and no deterioration of the device sensitivities. More recently, a 5-pixel filter matrix was designed and fabricated. Recent developments in pixelated coatings, shows that high performance infrared filters can be coated directly on detector for multispectral imaging. Next generation space instrument can benefit from this technology to reduce their weight and consumptions.

Bispectral Index Monitoring during Anesthesiologist-Directed Propofol and Remifentanil Sedation for Endoscopic Submucosal Dissection: A Prospective Randomized Controlled Trial

PubMed Central

Park, Woo Young; Shin, Yang-Sik; Lee, Sang Kil; Kim, So Yeon; Lee, Tai Kyung

2014-01-01

Purpose Endoscopic submucosal dissection (ESD) is a technically difficult and lengthy procedure requiring optimal depth of sedation. The bispectral index (BIS) monitor is a non-invasive tool that objectively evaluates the depth of sedation. The purpose of this prospective randomized controlled trial was to evaluate whether BIS guided sedation with propofol and remifentanil could reduce the number of patients requiring rescue propofol, and thus reduce the incidence of sedation- and/or procedure-related complications. Materials and Methods A total of 180 patients who underwent the ESD procedure for gastric adenoma or early gastric cancer were randomized to two groups. The control group (n=90) was monitored by the Modified Observer's Assessment of Alertness and Sedation scale and the BIS group (n=90) was monitored using BIS. The total doses of propofol and remifentanil, the need for rescue propofol, and the rates of complications were recorded. Results The number of patients who needed rescue propofol during the procedure was significantly higher in the control group than the BIS group (47.8% vs. 30.0%, p=0.014). There were no significant differences in the incidence of sedation- and/or procedure-related complications. Conclusion BIS-guided propofol infusion combined with remifentanil reduced the number of patients requiring rescue propofol in ESD procedures. However, this finding did not lead to clinical benefits and thus BIS monitoring is of limited use during anesthesiologist-directed sedation. PMID:25048506

Performance of the bispectral index during electrocautery.

PubMed

Chan, Matthew T V; Ho, Sin Shing; Gin, Tony

2012-01-01

The electroencephalogram contains small electrical signals that are vulnerable to contamination from high-frequency noise during electrocautery. The bispectral index (BIS) monitor incorporated hardware and software changes to eliminate artifacts, thus allowing BIS monitoring even in the presence of electrocautery. We evaluated the accuracy of BIS to measure anesthetic effect during electrocautery interference. Anesthesia was induced and maintained with target-controlled infusions of propofol (3 μg/mL) and remifentanil (4 ng/mL). After baseline BIS recordings, "simulated" electrocautery interference was induced continuously for 20 minutes. Five minutes after the start of electrocautery, propofol infusion was increased to achieve an effect site concentration of 6 μg/mL. Patients remained undisturbed during the study. BIS values and signal quality index were recorded continuously. During electrocautery, there was a significant decrease in signal quality index (mean difference: 16.9; 95% confidence intervals: 15.9-17.9; P<0.001). There was, however, no change in BIS value even after a step increase in propofol infusion from 3 to 6 μg/mL (P=0.93). In 22% of the patients there was a paradoxical increase in BIS values after doubling of propofol concentration. Following cessation of electrocautery, there was a prompt decrease in BIS (P<0.001), indicating a lack of response to the change in anesthetic depth during electrocautery. Rejecting and filtering artifacts from electrocautery interference reduced the ability of BIS to respond to a change in anesthetic depth. BIS values during electrocautery should be interpreted with caution.

Bispectral index monitoring during infant cardiac surgery: relationship of BIS to the stress response and plasma fentanyl levels.

PubMed

Kussman, B D; Gruber, E M; Zurakowski, D; Hansen, D D; Sullivan, L J; Laussen, P C

2001-11-01

We evaluated the relationship of the bispectral index (BIS) to commonly used indices of depth of anaesthesia in 19 infants enrolled in a prospective study of the stress response to hypothermic cardiopulmonary bypass. Group 1 (n=8) received high-dose fentanyl by bolus technique; group 2 (n=6) received high-dose fentanyl by continuous infusion; and group 3 (n=5) received a fentanyl-midazolam infusion. Blood pressure (BP), heart rate (HR) and plasma epinephrine, norepinephrine, cortisol, ACTH, glucose, lactate and fentanyl were analysed 15 min postinduction, 15 min poststernotomy, 15 min on CPB during cooling and during skin closure. Mean BIS (SD) values for all 19 patients were 45.3 (12.3), 40.4 (14.5), 24.4 (12.4) and 47.9 (13.9), at the successive time points. No significant differences were observed in changes in BIS over time between the groups. A significant correlation was found 15 min postinduction between BIS and BP (systolic r=0.51, mean r=0.56) in all groups, but not between BIS and HR. BIS did not correlate with BP or HR at any other time point. There was no significant correlation between BIS and hormonal, biochemical or plasma fentanyl levels for any group at any time point. We were unable to demonstrate a relationship between the BIS and haemodynamic, metabolic or hormonal indices of anaesthetic depth. Further evaluation of the BIS algorithm is required in neonates and infants.

Entropy is more resistant to artifacts than bispectral index in brain-dead organ donors.

PubMed

Wennervirta, Johanna; Salmi, Tapani; Hynynen, Markku; Yli-Hankala, Arvi; Koivusalo, Anna-Maria; Van Gils, Mark; Pöyhiä, Reino; Vakkuri, Anne

2007-01-01

To evaluate the usefulness of entropy and the bispectral index (BIS) in brain-dead subjects. A prospective, open, nonselective, observational study in the university hospital. 16 brain-dead organ donors. Time-domain electroencephalography (EEG), spectral entropy of the EEG, and BIS were recorded during solid organ harvest. State entropy differed significantly from 0 (isoelectric EEG) 28%, response entropy 29%, and BIS 68% of the total recorded time. The median values during the operation were state entropy 0.0, response entropy 0.0, and BIS 3.0. In four of 16 organ donors studied the EEG was not isoelectric, and nonreactive rhythmic activity was noted in time-domain EEG. After excluding the results from subjects with persistent residual EEG activity state entropy, response entropy, and BIS values differed from zero 17%, 18%, and 62% of the recorded time, respectively. Median values were 0.0, 0.0, and 2.0 for state entropy, response entropy, and BIS, respectively. The highest index values in entropy and BIS monitoring were recorded without neuromuscular blockade. The main sources of artifacts were electrocauterization, 50-Hz artifact, handling of the donor, ballistocardiography, electromyography, and electrocardiography. Both entropy and BIS showed nonzero values due to artifacts after brain death diagnosis. BIS was more liable to artifacts than entropy. Neither of these indices are diagnostic tools, and care should be taken when interpreting EEG and EEG-derived indices in the evaluation of brain death.

Cirrus Cloud Optical and Microphysical Property Retrievals from eMAS During SEAC4RS Using Bi-Spectral Reflectance Measurements Within the 1.88 micron Water Vapor Absorption Band

NASA Technical Reports Server (NTRS)

Meyer, K.; Platnick, S.; Arnold, G. T.; Holz, R. E.; Veglio, P.; Yorks, J.; Wang, C.

2016-01-01

Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or midwave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASAs SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 micron water vapor absorption band, namely the 1.83 and 1.93 micron channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below cloud water vapor absorption minimizes the surface contribution to measured cloudy TOA reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption, as well as reduces the frequency of retrieval failures for thin cirrus clouds.

Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88 µm water vapor absorption band

NASA Astrophysics Data System (ADS)

Meyer, Kerry; Platnick, Steven; Arnold, G. Thomas; Holz, Robert E.; Veglio, Paolo; Yorks, John; Wang, Chenxi

2016-04-01

Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

Utilizing bi-spectral index (BIS) for the monitoring of sedated adult ICU patients: a systematic review.

PubMed

Bilgili, Beliz; Montoya, Juan C; Layon, A J; Berger, Andrea L; Kirchner, H L; Gupta, Leena K; Gloss, David S

2017-03-01

The ideal level of sedation in the ICU is an ongoing source of scrutiny. At higher levels of sedation, the current scoring systems are not ideal. BIS may be able to improve both. We evaluated literature on effectiveness of BIS monitoring in sedated mechanically ventilated (MV) ICU patients compared to clinical sedation scores (CSS). For this systematic review, full text articles were searched in OVID, MEDLINE, EMBASE, and Cochrane databases from 1986 - 2014. Additional studies were identified searching bibliographies/abstracts from national/international Critical Care Medicine conferences and references from searched articles retrieved. Search terms were: 'Clinical sedation scale, Bi-spectral Index, Mechanical ventilation, Intensive care Unit'. Included were prospective, randomized and non-randomized studies comparing BIS monitoring with any CSS in MV adult (>18 yr old) ICU patients. Studies were graded for quality of evidence based on bias as established by the GRADE guidelines. Additional sources of bias were examined. There were five studies which met inclusion criteria. All five studies were either unclear or high risk for blinding of participants and blinding of outcome assessment. All papers had at least one source of additional high risk, or unclear/unstated. BIS monitoring in the mechanically ventilated ICU patient may decrease sedative drug dose, recall, and time to wake-up. The studies suggesting this are severely limited methodologically. BIS, when compared to subjective CSSs, is not, at this time, clearly indicated. An appropriately powered randomized, controlled study is needed to determine if this monitoring modality is of use on the ICU.

Bispectral index, entropy, and quantitative electroencephalogram during single-agent xenon anesthesia.

PubMed

Laitio, Ruut M; Kaskinoro, Kimmo; Särkelä, Mika O K; Kaisti, Kaike K; Salmi, Elina; Maksimow, Anu; Långsjö, Jaakko W; Aantaa, Riku; Kangas, Katja; Jääskeläinen, Satu; Scheinin, Harry

2008-01-01

The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects. After mask induction with xenon and intubation, anesthesia was continued with xenon only. BIS, State Entropy and Response Entropy, and electroencephalogram were monitored throughout induction, steady-state anesthesia, and emergence. The performance of BIS, State Entropy, and Response Entropy were evaluated with prediction probability, sensitivity, and specificity analyses. The power spectrum of the raw electroencephalogram signal was calculated. The mean (SD) xenon concentration during anesthesia was 66.4% (2.4%). BIS, State Entropy, and Response Entropy demonstrated low prediction probability values at loss of response (0.455, 0.656, and 0.619) but 1 min after that the values were high (0.804, 0.941, and 0.929). Thereafter, equally good performance was demonstrated for all indices. At emergence, the prediction probability values to distinguish between steady-state anesthesia and return of response for BIS, State Entropy, and Response Entropy were 0.988, 0.892, and 0.992. No statistical differences between the performances of the monitors were observed. Quantitative electroencephalogram analyses showed generalized increase in total power (P < 0.001), delta (P < 0.001) and theta activity (P < 0.001), and increased alpha activity (P = 0.003) in the frontal brain regions. Electroencephalogram-derived depth of sedation indices BIS and Entropy showed a delay to detect loss of response during induction of xenon anesthesia. Both monitors performed well in distinguishing between conscious and unconscious states during steady-state anesthesia. Xenon-induced changes in electroencephalogram closely resemble those induced by propofol.

Correlation and agreement between the bispectral index vs. state entropy during hypothermic cardio-pulmonary bypass.

PubMed

Meybohm, P; Gruenewald, M; Höcker, J; Renner, J; Graesner, J-T; Ilies, C; Scholz, J; Bein, B

2010-02-01

The bispectral index (BIS) and spectral entropy enable monitoring the depth of anaesthesia. Mild hypothermia has been shown to affect the ability of electroencephalography monitors to reflect the anaesthetic drug effect. The purpose of this study was to investigate the effect of hypothermia during a cardio-pulmonary bypass on the correlation and agreement between the BIS and entropy variables compared with normothermic conditions. This prospective clinical study included coronary artery bypass grafting patients (n=25) evaluating correlation and agreement (Bland-Altman analysis) between the BIS and both spectral and response entropy during a hypothermic cardio-pulmonary bypass (31-34 degrees C) compared with nomothermic conditions (34-37.5 degrees C). Anaesthesia was maintained with propofol and sufentanil and adjusted clinically, while the anaesthetist was blinded to the monitors. The BIS and entropy values decreased during cooling (P<0.05), but the decrease was more pronounced for entropy variables compared with BIS (P<0.05). The correlation coefficients (bias+/-SD; percentage error) between the BIS vs. spectral state entropy and response entropy were r(2)=0.56 (1+/-11; 42%) and r(2)=0.58 (-2+/-11; 43%) under normothermic conditions, and r(2)=0.17 (10+/-12; 77%) and r(2)=0.18 (9+/-11; 68%) under hypothermic conditions, respectively. Bias was significantly increased under hypothermic conditions (P<0.001 vs. normothermia). Acceptable agreement was observed between the BIS and entropy variables under normothermic but not under hypothermic conditions. The BIS and entropy variables may therefore not be interchangeable during a hypothermic cardio-pulmonary bypass.

Comparative evaluation of bispectral index system after sedation with midazolam and propofol combined with remifentanil versus ketamine in uncooperative during dental procedures

PubMed Central

Eshghi, Alireza; Mohammadpour, Mehrnaz; Kaviani, Nasser; Tahririan, Dana; Akhlaghi, Najmeh

2016-01-01

Background: Proper analgesic agents should be used in combination with sedative agents. Remifentanil is a synthetic narcotic/analgesic agent with a short duration effect and decreases the risk of apnea during recovery. Bispectral index system (BIS) is a new noninvasive technique for the evaluation of the depth of sedation. The aim of present clinical trial was to evaluate and compare the efficacy of intravenous sedation with propofol/midazolam/remifentanil (PMR) in comparison to propofol/midazolam/ketamine (PMK) for dental procedures in children 3-7 years of age. Materials and Methods: In this clinical trial, 32 healthy uncooperative children who were candidates for dental treatments under sedation were randomly divided into two groups. Intravenous sedation was induced with PMR in one group and with PMK in the other group. After injection and during procedure BIS index, heart rate and respiratory rate, blood pressure, and oxygen saturation was evaluated every 5 min. After the procedure, recovery time was measured. Data were analyzed with ANOVA, Friedman, Wilcoxon, and t-test. Results: The BIS value was significantly low in ketamin group (P = 0.003) but respiratory rates and heart rates were same in both groups with no statistical difference (P = 0.884, P = 0.775). The recovery time was significantly shorter in remifentanil group (P = 0.008 and P = 0.003). Conclusion: It can be concluded that intravenous sedation technique with PMR combination induces effective and safe sedation, with less pain and more forgetfulness and a shorter recovery time for children 3-7 years of age during dental procedures. PMID:26962308

Bispectral index-guided general anaesthesia in combination with interscalene block reduces desflurane consumption in arthroscopic shoulder surgery: a clinical comparison of bupivacaine versus levobupivacaine.

PubMed

Ozturk, Levent; Kesimci, Elvin; Albayrak, Tuna; Kanbak, Orhan

2015-07-21

The goal of this study was to compare the influence of an interscalene brachial plexus block (ISB) performed with either bupivacaine or levobupivacaine in conjunction with general anaesthesia (GA) on desflurane consumption, which was titrated to maintain the recovery profiles and postoperative analgesia while also keeping the bispectral index score (BIS) between 40 and 60 in patients undergoing arthroscopic shoulder surgery. Sixty patients undergoing arthroscopic shoulder surgery were prospectively randomized to receive GA with desflurane alone (group C) or in combination with a preoperative ISB by either bupivacaine 0.25 % (group B) 40 ml or levobupivacaine 0.25 % (group L) 40 ml. BIS scores or respiratory and hemodynamic parameters during the operation, recovery characteristics, consumed doses of desflurane and pain intensities were evaluated. The eye opening time was 4.0 ± 2.5 minutes for group B, 4.6 ± 2.4 minutes for group L, and 6.2 ± 2.1 minutes for group C (p < 0.05). Group B and group L saved 36 % and 25 % desflurane per unit time respectively when compared with group C (p < 0.001and p < 0.05) while the mean pain scores and analgesic requirements the first day after surgery were higher in group C (p < 0.05). Because of lower desflurane consumption, a superior recovery profile, and a high degree of patient acceptance, general anaesthesia in combination with interscalene block may be preferred in arthroscopic shoulder surgery. The trial registration number is ACTRN12613000381785.

Bispectral analysis during deep sedation of pediatric oral surgery patients.

PubMed

Overly, Frank L; Wright, Robert O; Connor, Francis A; Jay, Gregory D; Linakis, James G

2005-02-01

Bispectral (BIS) analysis uses electroencephalogram information from a forehead electrode to calculate an index score (0 to 100; 0 = coma; 90 to 100 = awake). This index score correlates with the level of alertness in anesthetized patients. Classically, sedation has been monitored with clinical sedation scales such as the Observers Assessment of Alertness Sedation Scale (OAA/S), Modified Ramsey Scale, or a Visual Analog Scale (VAS). Our objective was to determine the correlation between clinical sedation scales and BIS index in pediatric patients undergoing sedation in an outpatient oral surgery setting. Prospective cohort study of patients aged 2 to 17 years undergoing sedation in an outpatient oral surgery office. Sedation was performed in the customary manner with the addition of BIS monitoring. Three clinical sedation scores (OAA/S: 5 to 1; 5 = awake, 1 = unresponsive; Modified Ramsey: 1 to 6; 1-2 = awake, 6 = unresponsive; VAS: 0 to 10; 0 = awake, 10 = unresponsive) were assigned every 5 minutes by an investigator blinded to the BIS index. Data were analyzed using a repeated measures linear regression model. Sixteen subjects undergoing oral surgery, ages 4.5 years to 17 years, were enrolled, mean age 12.6 years +/- 4.3 years (standard deviation). Patients received methohexital in addition to 1 or more of the following: nitrous oxide, fentanyl, or midazolam. The results of the longitudinal regression analysis showed a highly significant association between the sedation scales and the BIS index. The BIS monitor may be a useful adjunct in monitoring pediatric patients receiving sedation in the outpatient setting.

A Bispectral Composite Threshold Approach for Automatic Cloud Detection in VIIRS Imagery

NASA Technical Reports Server (NTRS)

LaFontaine Frank J.; Jedlovec, Gary J.

2015-01-01

The detection of clouds in satellite imagery has a number of important applications in weather and climate studies. The presence of clouds can alter the energy budget of the Earth-atmosphere system through scattering and absorption of shortwave radiation and the absorption and re-emission of infrared radiation at longer wavelengths. The scattering and absorption characteristics of clouds vary with the microphysical properties of clouds, hence the cloud type. Thus, detecting the presence of clouds over a region in satellite imagery is important in order to derive atmospheric or surface parameters that give insight into weather and climate processes. For many applications however, clouds are a contaminant whose presence interferes with retrieving atmosphere or surface information. In these cases, is important to isolate cloud-free pixels, used to retrieve atmospheric thermodynamic information or surface geophysical parameters, from cloudy ones. This abstract describes an application of a two-channel bispectral composite threshold (BCT) approach applied to VIIRS imagery. The simplified BCT approach uses only the 10.76 and 3.75 micrometer spectral channels from VIIRS in two spectral tests; a straight-forward infrared threshold test with the longwave channel and a shortwave - longwave channel difference test. The key to the success of this approach as demonstrated in past applications to GOES and MODIS data is the generation of temporally and spatially dependent thresholds used in the tests from a previous number of days at similar observations to the current data. The paper and subsequent presentation will present an overview of the approach and intercomparison results with other satellites, methods, and against verification data.

Block-Dependent Sedation during Epidural Anaesthesia is Associated with Delayed Brainstem Conduction

PubMed Central

Wadhwa, Anupama; Shah, Yunus M.; Lin, Chum-Ming; Haugh, Gilbert S.; Sessler, Daniel I.

2005-01-01

Neuraxial anaesthesia produces a sedative and anesthetic-sparing effect. Recent evidence suggests that spinal cord anaesthesia modifies reticulo-thalamo-cortical arousal by decreasing afferent sensory transmission. We hypothesized that epidural anaesthesia produces sensory deafferentation-dependent sedation that is associated with impairment of brainstem transmission. We used brainstem auditory evoked potentials (BAEP) to evaluate reticular function in 11 volunteers. Epidural anaesthesia was induced with 2% 2-chloroprocaine. Hemodynamic and respiratory responses, sensory block level, sedation depth and BAEP were assessed throughout induction and resolution of epidural anaesthesia. Sedation was evaluated using verbal rating score (VRS), observer's assessment alertness/sedation (OAA/S) score, and bispectral index (BIS). Prediction probability (PK) was used to associate sensory block with sedation, as well as BIS with other sedation measures. Spearman rank order correlation was used to associate block level and sedation with the absolute and interpeak BAEP latencies. Sensory block level significantly predicted VRS (PK = 0.747), OAA/S score (PK = 0.748) and BIS. Bispectral index predicted VRS and OAA/S score (PK = 0.728). The latency of wave III of BAEP significantly correlated with sedation level (rho = 0.335, P < 0.01) and sensory block (rho = 0.394, P < 0.01). The other BAEP parameters did not change during epidural anaesthesia. Hemodynamic and respiratory responses remained stable throughout the study. Sedation during epidural anaesthesia depends on sensory block level and is associated with detectable block-dependent alterations in the brainstem auditory evoked responses. Sensory deafferentation may reduce CNS alertness through mechanisms related to brainstem neural activity. PMID:15220178

[Monitoring of brain function].

PubMed

Doi, Matsuyuki

2012-01-01

Despite being the most important of organs, the brain is disproportionately unmonitored compared to other systems such as cardiorespiratory in anesthesia settings. In order to optimize level of anesthesia, it is important to quantify the brain activity suppressed by anesthetic agents. Adverse cerebral outcomes remain a continued problem in patients undergoing various surgical procedures. By providing information on a range of physiologic parameters, brain monitoring may contribute to improve perioperative outcomes. This article addresses the various brain monitoring equipments including bispectral index (BIS), auditory evoked potentials (AEP), near-infrared spectroscopy (NIRS), transcranial Doppler ultrasonography (TCD) and oxygen saturation of the jugular vein (Sjv(O2)).

Frontal-temporal synchronization of EEG signals quantified by order patterns cross recurrence analysis during propofol anesthesia.

PubMed

Shalbaf, Reza; Behnam, Hamid; Sleigh, Jamie W; Steyn-Ross, D Alistair; Steyn-Ross, Moira L

2015-05-01

Characterizing brain dynamics during anesthesia is a main current challenge in anesthesia study. Several single channel electroencephalogram (EEG)-based commercial monitors like the Bispectral index (BIS) have suggested to examine EEG signal. But, the BIS index has obtained numerous critiques. In this study, we evaluate the concentration-dependent effect of the propofol on long-range frontal-temporal synchronization of EEG signals collected from eight subjects during a controlled induction and recovery design. We used order patterns cross recurrence plot and provide an index named order pattern laminarity (OPL) to assess changes in neuronal synchronization as the mechanism forming the foundation of conscious perception. The prediction probability of 0.9 and 0.84 for OPL and BIS specified that the OPL index correlated more strongly with effect-site propofol concentration. Also, our new index makes faster reaction to transients in EEG recordings based on pharmacokinetic and pharmacodynamic model parameters and demonstrates less variability at the point of loss of consciousness (standard deviation of 0.04 for OPL compared with 0.09 for BIS index). The result show that the OPL index can estimate anesthetic state of patient more efficiently than the BIS index in lightly sedated state with more tolerant of artifacts.

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds.

PubMed

Miller, Daniel J; Zhang, Zhibo; Ackerman, Andrew S; Platnick, Steven; Baum, Bryan A

2016-04-27

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness ( τ ) and effective radius ( r e ) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5-10 g/m 2 . In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic r e profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques.

The impact of cloud vertical profile on liquid water path retrieval based on the bispectral method: A theoretical study based on large-eddy simulations of shallow marine boundary layer clouds

PubMed Central

Miller, Daniel J.; Zhang, Zhibo; Ackerman, Andrew S.; Platnick, Steven; Baum, Bryan A.

2018-01-01

Passive optical retrievals of cloud liquid water path (LWP), like those implemented for Moderate Resolution Imaging Spectroradiometer (MODIS), rely on cloud vertical profile assumptions to relate optical thickness (τ) and effective radius (re) retrievals to LWP. These techniques typically assume that shallow clouds are vertically homogeneous; however, an adiabatic cloud model is plausibly more realistic for shallow marine boundary layer cloud regimes. In this study a satellite retrieval simulator is used to perform MODIS-like satellite retrievals, which in turn are compared directly to the large-eddy simulation (LES) output. This satellite simulator creates a framework for rigorous quantification of the impact that vertical profile features have on LWP retrievals, and it accomplishes this while also avoiding sources of bias present in previous observational studies. The cloud vertical profiles from the LES are often more complex than either of the two standard assumptions, and the favored assumption was found to be sensitive to cloud regime (cumuliform/stratiform). Confirming previous studies, drizzle and cloud top entrainment of dry air are identified as physical features that bias LWP retrievals away from adiabatic and toward homogeneous assumptions. The mean bias induced by drizzle-influenced profiles was shown to be on the order of 5–10 g/m2. In contrast, the influence of cloud top entrainment was found to be smaller by about a factor of 2. A theoretical framework is developed to explain variability in LWP retrievals by introducing modifications to the adiabatic re profile. In addition to analyzing bispectral retrievals, we also compare results with the vertical profile sensitivity of passive polarimetric retrieval techniques. PMID:29637042

Comparison of Bispectral Index and Entropy values with electroencephalogram during surgical anaesthesia with sevoflurane.

PubMed

Aho, A J; Kamata, K; Jäntti, V; Kulkas, A; Hagihira, S; Huhtala, H; Yli-Hankala, A

2015-08-01

Concomitantly recorded Bispectral Index® (BIS) and Entropy™ values sometimes show discordant trends during general anaesthesia. Previously, no attempt had been made to discover which EEG characteristics cause discrepancies between BIS and Entropy. We compared BIS and Entropy values, and analysed the changes in the raw EEG signal during surgical anaesthesia with sevoflurane. In this prospective, open-label study, 65 patients receiving general anaesthesia with sevoflurane were enrolled. BIS, Entropy and multichannel digital EEG were recorded. Concurrent BIS and State Entropy (SE) values were selected. Whenever BIS and SE values showed ≥10-unit disagreement for ≥60 s, the raw EEG signal was analysed both in time and frequency domain. A ≥10-unit disagreement ≥60 s was detected 428 times in 51 patients. These 428 episodes accounted for 5158 (11%) out of 45 918 analysed index pairs. During EEG burst suppression, SE was higher than BIS in 35 out of 49 episodes. During delta-theta dominance, BIS was higher than SE in 141 out of 157 episodes. During alpha or beta activity, SE was higher than BIS in all 49 episodes. During electrocautery, both BIS and SE changed, sometimes in the opposite direction, but returned to baseline values after electrocautery. Electromyography caused index disagreement four times (BIS > SE). Certain specific EEG patterns, and artifacts, are associated with discrepancies between BIS and SE. Time and frequency domain analyses of the original EEG improve the interpretation of studies involving BIS, Entropy and other EEG-based indices. NCT01077674. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effects of music on sedation depth and sedative use during pediatric dental procedures.

PubMed

Ozkalayci, Ozlem; Araz, Coskun; Cehreli, Sevi Burcak; Tirali, Resmiye Ebru; Kayhan, Zeynep

2016-11-01

The study aimed to investigate the effects of listening to music or providing sound isolation on the depth of sedation and need for sedatives in pediatric dental patients. Prospective, randomized, and controlled study. Tertiary, university hospital. In total, 180 pediatric patients, American Society of Anesthesiologists physical status I and II, who were scheduled for dental procedures of tooth extraction, filling, amputation, and root treatment. Patients were categorized into 3 groups: music, isolation, and control. During the procedures, the patients in the music group listened to Vivaldi's The Four Seasons violin concertos by sound-isolating headphones, whereas the patients in the isolation group wore the headphones but did not listen to music. All patients were sedated by 0.1 mg/kg midazolam and 1 mg/kg propofol. During the procedure, an additional 0.5 mg/kg propofol was administered as required. Bispectral index was used for quantifying the depth of sedation, and total dosage of the propofol was used for sedative requirements. The patients' heart rates, oxygen saturations, and Observer's Assessment of Alertness and Sedation Scale and bispectral index scores, which were monitored during the operation, were similar among the groups. In terms of the amount of propofol used, the groups were similar. Prolonged postoperative recovery cases were found to be significantly frequent in the control group, according to the recovery duration measurements (P = .004). Listening to music or providing sound isolation during pediatric dental interventions did not alter the sedation level, amount of medication, and hemodynamic variables significantly. This result might be due to the deep sedation levels reached during the procedures. However, listening to music and providing sound isolation might have contributed in shortening the postoperative recovery duration of the patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Bispectral Index monitoring in cancer patients undergoing palliative sedation: a preliminary report.

PubMed

Monreal-Carrillo, Edith; Allende-Pérez, Silvia; Hui, David; García-Salamanca, Maria-Fernanda; Bruera, Eduardo; Verástegui, Emma

2017-10-01

Continuous palliative sedation (PS) is currently titrated based on clinical observation; however, it is often unclear if patients are still aware of their suffering. The aim of this prospective study is to characterize the level of consciousness in patients undergoing PS using Bispectral Index (BIS) monitoring. We enrolled consecutive patients with refractory symptoms requiring PS. We documented the level of sedation using Ramsay Sedation Scale (RSS) and BIS at 0, 2, 4, 6, 12, and 24 h during the first day of PS and examined their degree of association. Intravenous midazolam or propofol was titrated according to the sedation level. Twenty patients on PS were recruited and had BIS continuous monitoring. Delirium was the most frequent reason for PS (n = 15, 75%). The median time of sedation was 24.5 h (interquartile range 6-46). The average time to achieve the desired sedation level was 6 h, and dose titration was required in 80% of the cases. At baseline, 14 (70%) patients were considered to be awake according to RSS (i.e., 1-3) and 19 (95%) were awake according to BIS (i.e., >60%). This proportion decreased to 31 and 56% at 4 h, 27% and 53 at 6 h, and 22 and 33% at 24 h. RS and BIS had moderate correlation (rho = -0.58 to -0.65); however, a small proportion of patients were found to be awake by BIS (i.e., ≥60%) despite clinical observation (i.e., RSS 4-6) indicating otherwise. The BIS is a noninvasive, bedside, real-time continuous monitoring method that may facilitate the objective assessment of level of consciousness and dose titration in patients undergoing PS.

A Phase 1, Single-center, Double-blind, Placebo-controlled Study in Healthy Subjects to Assess the Safety, Tolerability, Clinical Effects, and Pharmacokinetics-Pharmacodynamics of Intravenous Cyclopropyl-methoxycarbonylmetomidate (ABP-700) after a Single Ascending Bolus Dose.

PubMed

Struys, Michel M R F; Valk, Beatrijs I; Eleveld, Douglas J; Absalom, Anthony R; Meyer, Peter; Meier, Sascha; den Daas, Izaak; Chou, Thomas; van Amsterdam, Kai; Campagna, Jason A; Sweeney, Steven P

2017-07-01

Cyclopropyl-methoxycarbonylmetomidate (ABP-700) is a new "soft" etomidate analog. The primary objectives of this first-in-human study were to describe the safety and efficacy of ABP-700 and to determine its maximum tolerated dose. Secondary objectives were to characterize the pharmacokinetics of ABP-700 and its primary metabolite (cyclopropyl-methoxycarbonyl acid), to assess the clinical effects of ABP-700, and to investigate the dose-response and pharmacokinetic/pharmacodynamic relationships. Sixty subjects were divided into 10 cohorts and received an increasing, single bolus of either ABP-700 or placebo. Safety was assessed by clinical laboratory evaluations, infusion-site reactions, continuous monitoring of vital signs, physical examination, adverse event monitoring, and adrenocorticotropic hormone stimulation testing. Clinical effects were assessed with modified observer's assessment of alertness/sedation and Bispectral Index monitoring. Pharmacokinetic parameters were calculated. Stopping criteria were met at 1.00 mg/kg dose. No serious adverse events were reported. Adverse events were dose-dependent and comprised involuntary muscle movement, tachycardia, and ventilatory effects. Adrenocorticotropic hormone stimulation evoked a physiologic cortisol response in all subjects, no different from placebo. Pharmacokinetics were dose-proportional. A three-compartment pharmacokinetic model described the data well. A rapid onset of anesthesia/sedation after bolus administration and also a rapid recovery were observed. A quantitative concentration-effect relationship was described for the modified observer's assessment of alertness/sedation and Bispectral Index. This first-in-human study of ABP-700 shows that ABP-700 was safe and well tolerated after single-bolus injections up to 1.00 mg/kg. Bolus doses of 0.25 and 0.35 mg/kg were found to provide the most beneficial clinical effect versus side-effect profile.

Clinical evaluation of a simultaneous closed-loop anaesthesia control system for depth of anaesthesia and neuromuscular blockade*.

PubMed

Janda, M; Simanski, O; Bajorat, J; Pohl, B; Noeldge-Schomburg, G F E; Hofmockel, R

2011-12-01

We developed a closed-loop system to control the depth of anaesthesia and neuromuscular blockade using the bispectral index and the electromyogram simultaneously and evaluated the clinical performance of this combined system for general anaesthesia. Twenty-two adult patients were included in this study. Anaesthesia was induced by a continuous infusion of remifentanil at 0.4 μg.kg(-1) .min(-1) (induction dose) and then 0.25 μg.kg(-1) .min(-1) (maintenance dose) and propofol at 2 mg.kg(-1) 3 min later. The combined automatic control was started 2 min after tracheal intubation. The depth of anaesthesia was recorded using bispectral index monitoring using a target value of 40. The target value of neuromuscular blockade, using mivacurium, was a T1/T1(0) twitch height of 10%. The precision of the system was calculated using internationally defined performance parameters. Twenty patients were included in the data analysis. The mean (SD) duration of simultaneous control was 129 (69) min. No human intervention was necessary during the computer-controlled administration of propofol and mivacurium. All patients assessed the quality of anaesthesia as 'good' to 'very good'; there were no episodes of awareness. The mean (SD) median performance error, median absolute performance error and wobble for the control of depth of anaesthesia and for neuromuscular blockade were -0.31 (1.78), 6.76 (3.45), 6.32 (2.93) and -0.38 (1.68), 3.75 (4.83), 3.63 (4.69), respectively. The simultaneous closed-loop system using propofol and mivacurium was able to maintain the target values with a high level of precision in a clinical setting. © 2011 The Authors. Anaesthesia © 2011 The Association of Anaesthetists of Great Britain and Ireland.

Monitored anesthesia care (MAC) sedation: clinical utility of fospropofol

PubMed Central

Harris, Eric A; Lubarsky, David A; Candiotti, Keith A

2009-01-01

Fospropofol, a phosphorylated prodrug version of the popular induction agent propofol, is hydrolyzed in vivo to release active propofol, formaldehyde, and phosphate. Pharmacodynamic studies show fospropofol provides clinically useful sedation and EEG/bispectral index suppression while causing significantly less respiratory depression than propofol. Pain at the injection site, a common complaint with propofol, was not reported with fospropofol; the major patient complaint was transitory perianal itching during the drug’s administration. Although many clinicians believe fospropofol can safely be given by a registered nurse, the FDA mandated that fospropofol, like propofol, must be used only in the presence of a trained anesthesia provider. PMID:20057894

Electron-acoustic Instability Simulated By Modified Zakharov Equations

NASA Astrophysics Data System (ADS)

Jásenský, V.; Fiala, V.; Vána, O.; Trávnícek, P.; Hellinger, P.

We present non-linear equations describing processes in plasma when electron - acoustic waves are excited. These waves are present for instance in the vicinity of Earth's bow shock and in the polar ionosphere. Frequently they are excited by an elec- tron beam in a plasma with two electron populations, a cold and hot one. We derive modified Zakharov equations from kinetic theory for such a case together with numer- ical method for solving of this type of equations. Bispectral analysis is used to show which non-linear wave processes are of importance in course of the instability. Finally, we compare these results with similar simulations using Vlasov approach.

SASS: a bi-spectral panoramic IRST - results from measurement campaigns with the Italian Navy

NASA Astrophysics Data System (ADS)

de Ceglie, S. U.; Lo Moro, M.; Vita, R.; Neri, A.; Barani, G.; Cavallini, M.; Quaranta, C.; Colombi, G.

2010-04-01

Modern naval warfare asks for alerting system able to detect classical & asymmetric threats in support to radar in environment in which radar has reduced performance (on or near the sea surface). More, capability to offer high resolution images helps in ship identification, coastal & harbor surveillance as well as night navigation and rescue. All these tasks can be performed by an infrared search and track (IRST) system. This paper describes the IRST named Silent Acquisition and Surveillance System (SASS), developed for the Italian Navy and the tests jointly carried out by SELEX GALILEO and Italian Navy to characterize the system.

Coherent nonlinear coupling between a long-wavelength mode and small-scale turbulence in the TEXT tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsui, H.Y.W.; Rypdal, K.; Ritz, C.P.

1993-04-26

Bispectral analysis of Langmuir probe data indicates that coherent nonlinear coupling, in addition to the noncoherent turbulent interactions, exists in the edge plasma of the tokamak TEXT. Not all the modes involved reside within the spectral region of the usual broadband turbulence. At a major resonant surface the small-scale turbulent activity interacts [ital coherently] with a localized long-wavelength mode; a signature of regular or coherent structure. By the observed coupling to the transport related turbulence, the long-wavelength mode can influence plasma confinement indirectly. These observations signify the influence of low-order resonant surfaces on the edge turbulence in tokamaks.

Third-Order Spectral Techniques for the Diagnosis of Motor Bearing Condition Using Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Yang, D.-M.; Stronach, A. F.; MacConnell, P.; Penman, J.

2002-03-01

This paper addresses the development of a novel condition monitoring procedure for rolling element bearings which involves a combination of signal processing, signal analysis and artificial intelligence methods. Seven approaches based on power spectrum, bispectral and bicoherence vibration analyses are investigated as signal pre-processing techniques for application in the diagnosis of a number of induction motor rolling element bearing conditions. The bearing conditions considered are a normal bearing and bearings with cage and inner and outer race faults. The vibration analysis methods investigated are based on the power spectrum, the bispectrum, the bicoherence, the bispectrum diagonal slice, the bicoherence diagonal slice, the summed bispectrum and the summed bicoherence. Selected features are extracted from the vibration signatures so obtained and these are used as inputs to an artificial neural network trained to identify the bearing conditions. Quadratic phase coupling (QPC), examined using the magnitude of bispectrum and bicoherence and biphase, is shown to be absent from the bearing system and it is therefore concluded that the structure of the bearing vibration signatures results from inter-modulation effects. In order to test the proposed procedure, experimental data from a bearing test rig are used to develop an example diagnostic system. Results show that the bearing conditions examined can be diagnosed with a high success rate, particularly when using the summed bispectrum signatures.

Time-varying spectral analysis revealing differential effects of sevoflurane anaesthesia: non-rhythmic-to-rhythmic ratio.

PubMed

Lin, Y-T; Wu, H-T; Tsao, J; Yien, H-W; Hseu, S-S

2014-02-01

Heart rate variability (HRV) may reflect various physiological dynamics. In particular, variation of R-R peak interval (RRI) of electrocardiography appears regularly oscillatory in deeper levels of anaesthesia and less regular in lighter levels of anaesthesia. We proposed a new index, non-rhythmic-to-rhythmic ratio (NRR), to quantify this feature and investigated its potential to estimate depth of anaesthesia. Thirty-one female patients were enrolled in this prospective study. The oscillatory pattern transition of RRI was visualised by the time-varying power spectrum and quantified by NRR. The prediction of anaesthetic events, including skin incision, first reaction of motor movement during emergence period, loss of consciousness (LOC) and return of consciousness (ROC) by NRR were evaluated by serial prediction probability (PK ) analysis; the ability to predict the decrease of effect-site sevoflurane concentration was also evaluated. The results were compared with Bispectral Index (BIS). NRR well-predicted first reaction (PK  > 0.90) 30 s ahead, earlier than BIS and significantly better than HRV indices. NRR well-correlated with sevoflurane concentration, although its correlation was inferior to BIS, while HRV indices had no such correlation. BIS indicated LOC and ROC best. Our findings suggest that NRR provides complementary information to BIS regarding the differential effects of anaesthetics on the brain, especially the subcortical motor activity. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Detection and analysis of high-temperature events in the BIRD mission

NASA Astrophysics Data System (ADS)

Zhukov, Boris; Briess, Klaus; Lorenz, Eckehard; Oertel, Dieter; Skrbek, Wolfgang

2005-01-01

The primary mission objective of a new small Bi-spectral InfraRed Detection (BIRD) satellite is detection and quantitative analysis of high-temperature events like fires and volcanoes. An absence of saturation in the BIRD infrared channels makes it possible to improve false alarm rejection as well as to retrieve quantitative characteristics of hot targets, including their effective fire temperature, area and the radiative energy release. Examples are given of detection and analysis of wild and coal seam fires, of volcanic activity as well as of oil fires in Iraq. The smallest fires detected by BIRD, which were verified on ground, had an area of 12m2 at daytime and 4m2 at night.

Frailty Related to Anesthesia guided by the Index "bispectraL" (FRAIL) study: study protocol for a randomized controlled trial.

PubMed

Le Guen, Morgan; Herr, Marie; Bizard, Antoine; Bichon, Caroline; Boichut, Nathalie; Chazot, Thierry; Liu, Ngai; Ankri, Joel; Fischler, Marc

2017-03-16

Currently, patients older than 60 years of age represent 25% of the population and are at an increased risk during surgery. Therefore, reducing postoperative morbidity and mortality is a major concern in medical research and practice. Dependence on caregivers and cognitive impairment represent two major risk factors in the elderly, especially in frail patients after surgery under general anesthesia. In this context, continuous monitoring of the depth of anesthesia using a bispectral index (BIS) sensor may reduce the occurrence of impairments by gaining better control of the anesthetic depth. The first aim of this study is to compare manual versus automated administration of intravenous anesthetics with regard to 6-month functional decline in persons aged 70 years and older. The secondary objective includes an evaluation of the influence of the frail phenotype on self-sufficiency in elderly patients after general anesthesia. After receiving ethical committee approval and written consent, a complete preoperative assessment of physiological reserve and self-sufficiency will be performed on patients more than 70 years old who are scheduled for surgery under general anesthesia. This evaluation will determine the patient's frailty status in three categories: robust, pre-frail, and frail. Then, patients will be randomized into two groups: manual administration of anesthetics guided by BIS sensor (manual group) or automated administration (automated group) with recording of the anesthesia. A second examination will be scheduled after 6 months to assess changes in functional abilities, cognitive functions, and frailty status. A priori calculation of sample size gives a population of 430 patients to be included in this multicenter trial. This clinical study is designed to detect any postoperative complications and deaths related to the performance of the general anesthesia guided by the BIS sensor and the preoperative functional status of the elderly: robust, pre-frail, or frail. ClinicalTrials.gov, NCT02524327 . Registered on 10 August 2015.

Effects of dexmedetomidine infusion during spinal anesthesia on hemodynamics and sedation

PubMed Central

Tarıkçı Kılıç, Ebru; Aydın, Gaye

2018-01-01

ABSTRACT Background: We evaluated the effects of intravenous dexmedetomidine during spinal anesthesia on hemodynamics, respiratory rate, oxygen saturation, sedpain, and compared them with those of saline infusion. Sixty American Society of Anesthesiologists physical status I and II cases were randomly divided into two groups. Patients were connected to the monitor after premedication, and spinal anesthesia was administered. Sensory and motor blockades were assessed using pinprick test and Bromage scale, respectively. Group I received dexmedetomidine infusion and Group II received saline infusion. Throughout the infusion process, hemodynamic data, respiratory rate, oxygen saturation, sedation, pain, Bromage score, amnesia, bispectral index, and side effects were recorded. Postoperative hemodynamic measurements, oxygen saturation, sedation, pain scores were obtained. Sedation and pain were evaluated using the Ramsay and visual analog scales, respectively. Analgesics were administered in cases with high scores on the visual analog scale. Postoperative analgesic consumption, side effects, treatments were recorded. No significant differences were found between the groups with respect to oxygen saturation, respiratory rate, pain, and side effects in the intraoperative period. Time to onset of sensorial block, maximum sensorial block, onset of motor block, and maximum motor block; bispectral index values; and apex heartbeat until 80 min of infusion, systolic arterial blood pressure until 90 min, and diastolic arterial blood pressure until 50 min were lower, whereas amnesia and sedation levels were higher in dexmedetomidine group. Postoperative pain and analgesic requirement were not different. Apex heartbeat at 15 min and systolic arterial blood pressure at 30 min were lower and sedation scores were higher in the dexmedetomidine infusion group. We demonstrated dexmedetomidine infusion had a hemodynamic depressant effect intraoperatively whereas it had no significant effect on peripheral oxygen saturation, respiratory rate, visual analog scale scores, and side effects. Dexmedetomidine infusion enhanced motor and sensory blockade quality and induced amnesia and sedation. PMID:29457538

Sugammadex at both high and low doses does not affect the depth of anesthesia or hemodynamics: a randomized double blind trial.

PubMed

Fassoulaki, Argyro; Chondrogiannis, Konstantinos; Staikou, Chryssoula

2017-04-01

Previous studies have shown that sugammadex decreases the anesthetic depth when administered to reverse the neuromuscular blockade produced by rocuronium/vecuronium. The aim of the present study was to investigate the effect of sugammadex alone on anesthetic depth and hemodynamics. Sixty patients scheduled for abdominal surgery participated in the study. Anesthesia was induced with thiopental/fentanyl and maintained with N 2 O/oxygen and sevoflurane concentrations adjusted to maintain Entropy and Bispectral Index (BIS) values between 40 and 50. Cis-atracurium 0.2 mg/kg was administered for neuromuscular blockade which was monitored with a TOF-Watch ® SX acceleromyograph. State entropy (SE), response entropy (RE), Bispectral Index (BIS), systolic (SAP) and diastolic blood pressure (DAP), heart rate (HR), SpO 2 , end-tidal CO 2 and sevoflurane concentrations were recorded every 3 min intraoperatively. Sugammadex 2 mg/kg (Group-2), 4 mg/kg (Group-4) or 16 mg/kg (Group-16) was given intravenously when a count of two responses of the train-of-four (TOF) or a post-tetanic count (PTC) 1-3 appeared or when no response at all (PTC = 0) was observed, respectively. The overall SE values, thus the primary outcome of the study, were 44 ± 11, 43 ± 10 and 43 ± 11 for Group-2, Group-4 and Group-16, respectively (p = 0.812). Also, the secondary endpoints, namely RE, BIS, SAP and DAP, HR and SpO 2 did not differ between the three groups. Comparisons between Group-2 versus Group-4, Group-2 versus Group-16 and Group-4 versus Group-16 showed no differences (p > 0.05) for all the studied variables. Sugammadex alone at low, medium or high clinical doses has no effect on anesthetic depth as assessed by Entropy and BIS or on hemodynamics.

Effects of stellate ganglion block on sedation as assessed by bispectral index in normal healthy volunteers.

PubMed

Yeo, Jinseok; Jeon, Younghoon

2015-01-01

The sympathetic nervous system plays an important role in the arousal response. Recently, the stellate ganglion block (SGB) was found to effectively treat anxiety and night awakening in humans and decrease electroencephalogram (EEG) indices of arousal responses in rat. But, the role of the sympathetic block in human arousal responses has not yet been studied. We performed this prospective, double-blinded, controlled volunteer study to investigate the sedative effects and bispectral index (BIS) changes of SGB. A randomized, double-blind trial. Single academic medical center. This study was approved by the Ethics Committee of Kyungpook National University Hospital (ref: KNUH-10-1081) and registered with CRiS (Clinical Research Information Service, http://cris.cdc.go.kr, ref: KCT0000036, 2010. 9.24). Twenty healthy volunteers were enrolled in this study. The volunteers were randomly assigned to one of 2 groups: the SGB group (n = 10) and the sham group (n =10). Volunteers in SGB group received SGB and volunteers in the sham group received a sham procedure. BIS value, heart rate, and blood pressure were measured before and 5, 10, 20, and 30 minutes after the procedure. Observer's Assessment of Alertness/Sedation (OAA/S) scores were assessed before and 10 and 30 minutes after the intervention. In the SGB group, BIS values and OAA/S scores significantly decreased after the intervention as compared to baseline (P < 0.05). The values were also significantly decreased in the SGB group when compared to the values in sham group after the intervention (P < 0.05). There was a significant change of mean blood pressure 10 to 30 minutes after SGB (P < 0.05). There were no differences in heart rate during study period between groups. This study is limited by a relatively small sample size. This study showed that SGB has a sedative effect in normal healthy volunteers, as evidenced by decreased OAA/S scores and BIS values.

An Adaptive Monitoring Scheme for Automatic Control of Anaesthesia in dynamic surgical environments based on Bispectral Index and Blood Pressure.

PubMed

Yu, Yu-Ning; Doctor, Faiyaz; Fan, Shou-Zen; Shieh, Jiann-Shing

2018-04-13

During surgical procedures, bispectral index (BIS) is a well-known measure used to determine the patient's depth of anesthesia (DOA). However, BIS readings can be subject to interference from many factors during surgery, and other parameters such as blood pressure (BP) and heart rate (HR) can provide more stable indicators. However, anesthesiologist still consider BIS as a primary measure to determine if the patient is correctly anaesthetized while relaying on the other physiological parameters to monitor and ensure the patient's status is maintained. The automatic control of administering anesthesia using intelligent control systems has been the subject of recent research in order to alleviate the burden on the anesthetist to manually adjust drug dosage in response physiological changes for sustaining DOA. A system proposed for the automatic control of anesthesia based on type-2 Self Organizing Fuzzy Logic Controllers (T2-SOFLCs) has been shown to be effective in the control of DOA under simulated scenarios while contending with uncertainties due to signal noise and dynamic changes in pharmacodynamics (PD) and pharmacokinetic (PK) effects of the drug on the body. This study considers both BIS and BP as part of an adaptive automatic control scheme, which can adjust to the monitoring of either parameter in response to changes in the availability and reliability of BIS signals during surgery. The simulation of different control schemes using BIS data obtained during real surgical procedures to emulate noise and interference factors have been conducted. The use of either or both combined parameters for controlling the delivery Propofol to maintain safe target set points for DOA are evaluated. The results show that combing BIS and BP based on the proposed adaptive control scheme can ensure the target set points and the correct amount of drug in the body is maintained even with the intermittent loss of BIS signal that could otherwise disrupt an automated control system.

Effect of age on the performance of bispectral and entropy indices during sevoflurane pediatric anesthesia: a pharmacometric study.

PubMed

Sciusco, Alberto; Standing, Joseph F; Sheng, Yucheng; Raimondo, Pasquale; Cinnella, Gilda; Dambrosio, Michele

2017-04-01

Bispectral index (BIS) and entropy monitors have been proposed for use in children, but research has not supported their validity for infants. However, effective monitoring of young children may be even more important than for adults, to aid appropriate anesthetic dosing and reduce the chance of adverse consequences. This prospective study aimed to investigate the relationships between age and the predictive performance of BIS and entropy monitors in measuring the anesthetic drug effects within a pediatric surgery setting. We concurrently recorded BIS and entropy (SE/RE) in 48 children aged 1 month-12 years, undergoing general anesthesia with sevoflurane and fentanyl. Nonlinear mixed effects modeling was used to characterize the concentration-response relationship independently between the three monitor indicators with sevoflurane. The model's goodness-of-fit was assessed by prediction-corrected visual predictive checks. Model fit with age was evaluated using absolute conditional individual weighted residuals (|CIWRES|). The ability of BIS and entropy monitors to describe the effect of anesthesia was compared with prediction probabilities (P K ) in different age groups. Intraoperative and awakening values were compared in the age groups. The correlation between BIS and entropy was also calculated. |CIWRES| vs age showed an increasing trend in the model's accuracy for all three indicators. P K probabilities were similar for all three indicators within each age group, though lower in infants. The linear correlations between BIS and entropy in different age groups were lower for infants. Infants also tended to have lower values during surgery and at awakening than older children, while toddlers had higher values. Performance of both monitors improves as age increases. Our results suggest a need for the development of new monitor algorithms or calibration to better account for the age-specific EEG dynamics of younger patients. © 2017 John Wiley & Sons Ltd.

Bispectral index values during sevoflurane-nitrous oxide general anesthesia in women undergoing cesarean delivery: a comparison between women with and without prior labor.

PubMed

Yoo, Kyung Y; Jeong, Cheol W; Kang, Myung W; Kim, Seok J; Chung, Sung T; Shin, Min H; Lee, JongUn

2008-06-01

An end-tidal concentration of 1% sevoflurane (1% ET(SEVO)) in 50% nitrous oxide (N(2)O) during elective cesarean delivery has been associated with bispectral index (BIS) values >60, which are associated with an increased risk of awareness. We hypothesized that BIS values during sevoflurane-N(2)O general anesthesia for cesarean delivery would be lower in women with prior labor compared with women without prior labor. Forty patients undergoing cesarean delivery were enrolled in this observational study. One group had urgent surgery after labor (labor group, n = 20) and the other had elective surgery without labor (control group, n = 20). General anesthesia was induced with thiopental 4 mg/kg, followed by succinylcholine 1.5 mg/kg, and maintained with 1% ET(SEVO) and 50% N(2)O in oxygen. BIS values, systolic arterial blood pressure, heart rate, plasma stress hormone concentrations, Apgar scores, and postoperative analgesia variables were assessed and compared between groups. BIS values during the period between intubation and delivery were lower in the labor group than in the control group (P < 0.001). Plasma norepinephrine concentrations increased at delivery compared with baseline in both groups. They were higher in the labor group than in the control group both at baseline and at delivery. Systolic arterial blood pressure, heart rate, Apgar scores, surgical characteristics, and plasma concentrations of vasopressin and cortisol were not different between groups. Postoperative visual analog scale pain scores were similar between groups, while the labor group consumed less analgesics (P < 0.01) during the first 24 h after the operation. Prior labor was associated with lower intraoperative BIS values during sevoflurane/N(2)O general anesthesia and reduced postoperative analgesic consumption in women undergoing cesarean delivery compared with women without prior labor.

The relationship between serum progesterone concentration and anesthetic and analgesic requirements: a prospective observational study of parturients undergoing cesarean delivery.

PubMed

Lee, Jeongwoo; Lee, Junho; Ko, Seonghoon

2014-10-01

In clinical practice, pregnant women have lower anesthetic requirements for general anesthesia than nonpregnant women. Although the hormonal changes such as progesterone associated with pregnancy may affect the minimum alveolar concentration of volatile anesthetics, the relationship between the anesthetic or analgesic requirements and progesterone level in full-term women has not been studied. In this study, we attempted to identify relationships between anesthetic or analgesic requirements and maternal serum concentrations of progesterone. We studied 100 parturients >36 weeks' gestation who were scheduled for planned cesarean delivery under general anesthesia. Venous blood was collected to measure the maternal progesterone concentration. Anesthesia was induced with 4 to 5 mg/kg thiopental and 0.8 mg/kg rocuronium. During anesthetic maintenance, sevoflurane 0.5% to 2.0% and nitrous oxide 50% in oxygen were titrated based on arterial blood pressure, heart rate, and bispectral index value. Vital signs, bispectral index, end-tidal sevoflurane concentration, and sevoflurane consumption per hour were recorded. Visual analog scale pain scores and cumulative analgesic consumption were recorded at 2, 24, and 48 hours postoperatively. The mean serum progesterone concentration was 128.2 ± 83.0 ng/mL. There was a significant negative correlation between sevoflurane consumption per hour and serum progesterone concentration (Pearson correlation r = -0.26; 95% confidence interval, -0.44 to -0.05, P = 0.01). Cumulative analgesic consumption at postoperative hours 2 (r = -0.20, P = 0.05), 24 (r = -0.25, P = 0.02), and 48 (r = -0.28, P = 0.01) were correlated inversely with serum progesterone concentration. Women with high progesterone levels (higher than the median value) had lower sevoflurane consumption per hour (P = 0.02) and 48-hour postoperative cumulative analgesic consumption (P = 0.02) than women with low (below the median value) levels. The decreased anesthetic and analgesic requirements of near full-term parturients might partially depend on serum progesterone concentration.

Spatial and Temporal Varying Thresholds for Cloud Detection in Satellite Imagery

NASA Technical Reports Server (NTRS)

Jedlovec, Gary; Haines, Stephanie

2007-01-01

A new cloud detection technique has been developed and applied to both geostationary and polar orbiting satellite imagery having channels in the thermal infrared and short wave infrared spectral regions. The bispectral composite threshold (BCT) technique uses only the 11 micron and 3.9 micron channels, and composite imagery generated from these channels, in a four-step cloud detection procedure to produce a binary cloud mask at single pixel resolution. A unique aspect of this algorithm is the use of 20-day composites of the 11 micron and the 11 - 3.9 micron channel difference imagery to represent spatially and temporally varying clear-sky thresholds for the bispectral cloud tests. The BCT cloud detection algorithm has been applied to GOES and MODIS data over the continental United States over the last three years with good success. The resulting products have been validated against "truth" datasets (generated by the manual determination of the sky conditions from available satellite imagery) for various seasons from the 2003-2005 periods. The day and night algorithm has been shown to determine the correct sky conditions 80-90% of the time (on average) over land and ocean areas. Only a small variation in algorithm performance occurs between day-night, land-ocean, and between seasons. The algorithm performs least well. during he winter season with only 80% of the sky conditions determined correctly. The algorithm was found to under-determine clouds at night and during times of low sun angle (in geostationary satellite data) and tends to over-determine the presence of clouds during the day, particularly in the summertime. Since the spectral tests use only the short- and long-wave channels common to most multispectral scanners; the application of the BCT technique to a variety of satellite sensors including SEVERI should be straightforward and produce similar performance results.

Pharmacokinetic and pharmacodynamic study of dexmedetomidine in elderly patients during spinal anesthesia.

PubMed

Kuang, Yun; Zhang, Ran-Ran; Pei, Qi; Tan, Hong-Yi; Guo, Cheng-Xian; Huang, Jie; Xiang, Yu-Xia; Ouyang, Wen; Duan, Kai-Ming; Wang, Sai-Ying; Yang, Guo-Ping

2015-12-01

The application of dexmedetomidine in patient sedation is generally accepted, though its clinical application is limited because of the lack of information detailing the specific properties among diverse populations of patients. The aim of this study was to compare the pharmacokinetic and pharmacodynamic characteristics of dexmedetomidine between elderly and young patients during spinal anesthesia. 34 subjects (elderly group: n = 15; young group: n = 19) with spinal anesthesia were enrolled in the present study following the inclusion/exclusion criteria detailed below. All subjects received intravenous infusion of dexmedetomidine with a loading dose of 0.5 µg x kg⁻¹ for 10 minutes and a maintenance dose of 0.5 µg x kg⁻¹ x h⁻¹ for 50 minutes. Plasma concentrations of dexmedetomidine were detected by the HPLC-MS/MS method and pharmacokinetic parameters were calculated using WinNolin software. There was no significant difference between the elderly and young subjects in major pharmacokinetic parameters. There was a marked gender difference in the Cmax (peak plasma concentration) and tmax (time to reach Cmax) between genders in elderly subjects, though in this cohort the other pharmacokinetic parameters were not significantly different. In the young subjects there were no noteworthy variations between genders in pharmacokinetic parameters. There was no significant difference between the two groups in BISAUC(0-t) (the area under the bispectral index-time curve from time 0 to t hours), BISmin (the minimum value of the bispectral index after drug delivery), and or tmin-BIS (bispectral index for the minimum value of time). SBP (systolic blood pressure), DBP (diastolic blood pressure), HR (heart rate), and SpO₂(pulse oxygen saturation) developed substantive differences in a time-dependent manner, but there were no statistically significant differences in these four indicators in the time*group at three time points (1 hour, 2 hours, and 3 hours after drug administration); while SBP was significantly different between the groups, this differential declined in a time-dependent manner, and there were no significant attendant differences in the D-value. The observed values and D-values of DBP and HR were similar in the groups, but the observed value and D-value of SpO₂did differ. There were 14 drug-related adverse events in the young group, and 26 drug-related adverse events in the elderly group, a 46% differential. The percentage of patients who requiring intervention during surgery was 68.75% (11/16) in the elderly group and 36.84% (7/19) in the young group, with no significant difference between the two groups once age was factored in (p = 0.06). None of the pharmacodynamic indices, however, correlated with the key pharmacokinetic parameters (Cmax, AUC(0→t), AUC(0→∞)) of dexmedetomidine. The clearance of dexmedetomidine in elderly patients showed a declining trend compared to young patients. Interventions in the elderly group were more frequent than in the young group, and the elderly group showed significant adverse effects. It is suggested that elderly patients who use dexmedetomidine may benefit from a different dose. However, further research with a larger population size is required to confirm these findings.

The Core Avionics System for the DLR Compact-Satellite Series

NASA Astrophysics Data System (ADS)

Montenegro, S.; Dittrich, L.

2008-08-01

The Standard Satellite Bus's core avionics system is a further step in the development line of the software and hardware architecture which was first used in the bispectral infrared detector mission (BIRD). The next step improves dependability, flexibility and simplicity of the whole core avionics system. Important aspects of this concept were already implemented, simulated and tested in other ESA and industrial projects. Therefore we can say the basic concept is proven. This paper deals with different aspects of core avionics development and proposes an extension to the existing core avionics system of BIRD to meet current and future requirements regarding flexibility, availability, reliability of small satellite and the continuous increasing demand of mass memory and computational power.

Comparison of simultaneous and sequential administration of fentanyl-propofol for surgical abortion: a randomized single-blinded controlled trial.

PubMed

Gao, Wei; Sha, Baoyong; Zhao, Yuan; Fan, Zhe; Liu, Lin; Shen, Xin

2017-08-01

Propofol lipid emulsion (PLE) is a nanosized sedative, and it is used with a combination of salted antalgic prodrug, fentanyl citrate (FC). To illustrate the synergistic effect of mixing, we compared the sedation/analgesia resulting from simultaneous and sequential administration in surgically induced abortion (No. ChiCTR-IPC-15006153). Simultaneous group showed lower bispectral index, blood pressure, and heart rate, when cannula was inserted into the uterus. It also showed less frequency of hypertension, sinus tachycardia, movement, pain at the injection site, and additional FC. Therefore, premixing of PLE and FC enhanced the sedation and analgesia; stabilized the hemodynamics; lessened the incidence of movement and injection pain; and reduced the requirement of drugs.

A global map of rainfed cropland areas (GMRCA) at the end of last millennium using remote sensing

USGS Publications Warehouse

Biradar, C.M.; Thenkabail, P.S.; Noojipady, P.; Li, Y.; Dheeravath, V.; Turral, H.; Velpuri, M.; Gumma, M.K.; Gangalakunta, O.R.P.; Cai, X.L.; Xiao, X.; Schull, M.A.; Alankara, R.D.; Gunasinghe, S.; Mohideen, S.

2009-01-01

The overarching goal of this study was to produce a global map of rainfed cropland areas (GMRCA) and calculate country-by-country rainfed area statistics using remote sensing data. A suite of spatial datasets, methods and protocols for mapping GMRCA were described. These consist of: (a) data fusion and composition of multi-resolution time-series mega-file data-cube (MFDC), (b) image segmentation based on precipitation, temperature, and elevation zones, (c) spectral correlation similarity (SCS), (d) protocols for class identification and labeling through uses of SCS R2-values, bi-spectral plots, space-time spiral curves (ST-SCs), rich source of field-plot data, and zoom-in-views of Google Earth (GE), and (e) techniques for resolving mixed classes by decision tree algorithms, and spatial modeling. The outcome was a 9-class GMRCA from which country-by-country rainfed area statistics were computed for the end of the last millennium. The global rainfed cropland area estimate from the GMRCA 9-class map was 1.13 billion hectares (Bha). The total global cropland areas (rainfed plus irrigated) was 1.53 Bha which was close to national statistics compiled by FAOSTAT (1.51 Bha). The accuracies and errors of GMRCA were assessed using field-plot and Google Earth data points. The accuracy varied between 92 and 98% with kappa value of about 0.76, errors of omission of 2-8%, and the errors of commission of 19-36%. ?? 2008 Elsevier B.V.

Sensitivity of spectral reflectance values to different burn and vegetation ratios: A multi-scale approach applied in a fire affected area

NASA Astrophysics Data System (ADS)

Pleniou, Magdalini; Koutsias, Nikos

2013-05-01

The aim of our study was to explore the spectral properties of fire-scorched (burned) and non fire-scorched (vegetation) areas, as well as areas with different burn/vegetation ratios, using a multisource multiresolution satellite data set. A case study was undertaken following a very destructive wildfire that occurred in Parnitha, Greece, July 2007, for which we acquired satellite images from LANDSAT, ASTER, and IKONOS. Additionally, we created spatially degraded satellite data over a range of coarser resolutions using resampling techniques. The panchromatic (1 m) and multispectral component (4 m) of IKONOS were merged using the Gram-Schmidt spectral sharpening method. This very high-resolution imagery served as the basis to estimate the cover percentage of burned areas, bare land and vegetation at pixel level, by applying the maximum likelihood classification algorithm. Finally, multiple linear regression models were fit to estimate each land-cover fraction as a function of surface reflectance values of the original and the spatially degraded satellite images. The main findings of our research were: (a) the Near Infrared (NIR) and Short-wave Infrared (SWIR) are the most important channels to estimate the percentage of burned area, whereas the NIR and red channels are the most important to estimate the percentage of vegetation in fire-affected areas; (b) when the bi-spectral space consists only of NIR and SWIR, then the NIR ground reflectance value plays a more significant role in estimating the percent of burned areas, and the SWIR appears to be more important in estimating the percent of vegetation; and (c) semi-burned areas comprising 45-55% burned area and 45-55% vegetation are spectrally closer to burned areas in the NIR channel, whereas those areas are spectrally closer to vegetation in the SWIR channel. These findings, at least partially, are attributed to the fact that: (i) completely burned pixels present low variance in the NIR and high variance in the SWIR, whereas the opposite is observed in completely vegetated areas where higher variance is observed in the NIR and lower variance in the SWIR, and (ii) bare land modifies the spectral signal of burned areas more than the spectral signal of vegetated areas in the NIR, while the opposite is observed in SWIR region of the spectrum where the bare land modifies the spectral signal of vegetation more than the burned areas because the bare land and the vegetation are spectrally more similar in the NIR, and the bare land and burned areas are spectrally more similar in the SWIR.

Sample entropy analysis for the estimating depth of anaesthesia through human EEG signal at different levels of unconsciousness during surgeries.

PubMed

Liu, Quan; Ma, Li; Fan, Shou-Zen; Abbod, Maysam F; Shieh, Jiann-Shing

2018-01-01

Estimating the depth of anaesthesia (DoA) in operations has always been a challenging issue due to the underlying complexity of the brain mechanisms. Electroencephalogram (EEG) signals are undoubtedly the most widely used signals for measuring DoA. In this paper, a novel EEG-based index is proposed to evaluate DoA for 24 patients receiving general anaesthesia with different levels of unconsciousness. Sample Entropy (SampEn) algorithm was utilised in order to acquire the chaotic features of the signals. After calculating the SampEn from the EEG signals, Random Forest was utilised for developing learning regression models with Bispectral index (BIS) as the target. Correlation coefficient, mean absolute error, and area under the curve (AUC) were used to verify the perioperative performance of the proposed method. Validation comparisons with typical nonstationary signal analysis methods (i.e., recurrence analysis and permutation entropy) and regression methods (i.e., neural network and support vector machine) were conducted. To further verify the accuracy and validity of the proposed methodology, the data is divided into four unconsciousness-level groups on the basis of BIS levels. Subsequently, analysis of variance (ANOVA) was applied to the corresponding index (i.e., regression output). Results indicate that the correlation coefficient improved to 0.72 ± 0.09 after filtering and to 0.90 ± 0.05 after regression from the initial values of 0.51 ± 0.17. Similarly, the final mean absolute error dramatically declined to 5.22 ± 2.12. In addition, the ultimate AUC increased to 0.98 ± 0.02, and the ANOVA analysis indicates that each of the four groups of different anaesthetic levels demonstrated significant difference from the nearest levels. Furthermore, the Random Forest output was extensively linear in relation to BIS, thus with better DoA prediction accuracy. In conclusion, the proposed method provides a concrete basis for monitoring patients' anaesthetic level during surgeries.

Effect-site half-time for burst suppression is longer than for hypnosis during anaesthesia with sevoflurane.

PubMed

Kennedy, R R; Minto, C; Seethepalli, A

2008-01-01

The relationship between measures of drug effect such as bispectral index (BIS) and end-tidal (ET) levels of anaesthetic agents is described by the 'effect site equilibrium half-time', t(1/2)(ke0). There are limited data available on sevoflurane t(1/2)(ke0) during routine anaesthesia and surgery. Preliminary observations suggested t(1/2)(ke0) for the degree of hypnosis as estimated by BIS is different from that for burst suppression of the electroencephalograph, occurring at 'deep' levels of anaesthesia. This study aimed to determine and compare t(1/2)(ke0) for these two 'effects'. Large changes in ET sevoflurane were produced in 13 subjects during surgery. ET sevoflurane, BIS, and burst suppression ratio (BSR) were recorded every 10 s. Data were divided into epochs with BIS>30 (BIS) or with BSR>10% (burst suppression). Using a non-parametric modelling technique, t(1/2)(ke0) was determined for each epoch. There were 36 'BIS' and 20 burst suppression zones. Mean (sd) t(1/2)(ke0) for BIS was 3.48 (1.12) min and for BSR 9.9 (6.4) min. In all subjects, t(1/2)(ke0) BIS

Entropy as an indicator of cerebral perfusion in patients with increased intracranial pressure.

PubMed

Khan, James; Mariappan, Ramamani; Venkatraghavan, Lashmi

2014-07-01

Changes in electroencephalogram (EEG) patterns correlate well with changes in cerebral perfusion pressure (CPP) and hence entropy and bispectral index values may also correlate with CPP. To highlight the potential application of entropy, an EEG-based anesthetic depth monitor, on indicating cerebral perfusion in patients with increased intracranial pressure (ICP), we report two cases of emergency neurosurgical procedure in patients with raised ICP where anesthesia was titrated to entropy values and the entropy values suddenly increased after cranial decompression, reflecting the increase in CPP. Maintaining systemic blood pressure in order to maintain the CPP is the anesthetic goal while managing patients with raised ICP. EEG-based anesthetic depth monitors may hold valuable information on guiding anesthetic management in patients with decreased CPP for better neurological outcome.

Effect of rocuronium on the bispectral index under anesthesia and tracheal intubation.

PubMed

Yue, Hui; Han, Jinyu; Liu, Ling; Wang, Kaiyuan; Li, Jincheng

2016-12-01

The aim of the present study was to investigate the effect of various doses of rocuronium on bispectral index (BIS) responses to propofol induction and tracheal intubation, as well as the role of the non-depolarization muscle relaxant rocuronium on the depth of sedation. A total of 72 patients (American Society of Anesthesiologists physical status I-II) were anaesthetized with propofol using a target-controlled infusion, and randomly divided into two sedation level groups (n=36). The patients were divided into 2 groups according to the BIS value: A normal sedation group (group 1), with a stable BIS value at 40-60, and a deep sedation group (group 2), with a BIS value <20 or with burst suppression. Each group was randomly divided into 4 subgroups A-D (n=9) according to the various doses of rocuronium (0.3, 0.6, 0.9 and 1.2 mg/kg). Tracheal intubation was performed after 2 min of rocuronium administration. BIS, electromyography (EMG), heart rate (HR) and mean arterial pressure (MAP) were recorded continuously and averaged over 1 min during baseline (T1), steady state (T2), 2 min after rocuronium infusion (T3), and 0, 2 and 5 min after tracheal intubation. The results demonstrated that HR and MAP decreased significantly at T2 and T3 compared with T1. Following tracheal intubation (L0), HR and MAP significantly increased compared with T2 and T3, and returned to levels similar to those prior to intubation after 5 min. In group 1C and 1D, BIS was significantly decreased at T3 compared with T2; BIS was significantly increased at L0 compared with T3 in group 1A and 1B. EMG at earlier stages of anesthesia was significantly higher compared with other points, and was significantly increased at L0 compared with T3 in group 1A and 1B. These results demonstrated that BIS response may be associated with the dosage of rocuronium in the normal sedation group, although no association was observed with the deep sedation group. Tracheal intubation resulted in marked hemodynamic changes under both normal and deep sedation.

Evaluation of entropy for monitoring the depth of anesthesia compared with bispectral index: a multicenter clinical trial.

PubMed

Gao, Jian-dong; Zhao, Yu-jie; Xu, Chen-shi; Zhao, Jing; Huang, Yu-guang; Wang, Tian-long; Pei, Ling; Wang, Jian; Yao, Li-nong; Ding, Qian; Tan, Zhi-ming; Zhu, Zhi-rong; Yue, Yun

2012-04-01

As a new electroencephalogram (EEG) signal processing technique for monitoring the depth of anesthesia, entropy consists of two indices: reaction entropy (RE) and state entropy (SE). Our study compared entropy with classical bispectral index (BIS) in reduction of myoelectrical interference and noxious stimuli with EEG signals. Two hundred and eighty patients (ASA I-II, 18-60 years old) undergoing scheduled surgeries from seven medical centers were enrolled. Anesthesia induction was managed with propofol via the target-controlled infusion (TCI) system. The results of BIS, RE, SE, mean arterial pressure (MAP) and heart rate (HR) were recorded before anesthesia induction, at the moment of unconsciousness, before and 2 minutes after administration of muscle relaxant, and before and one and three minutes after the tracheal intubation. The values of half maximum effective concentrations (EC50), 5% effective concentrations (EC05) and 95% effective concentrations (EC95) of propofol effect-site concentration at the onset of unconsciousness were 1.2 (1.1-1.3 µg/ml), 2.5 (2.4-2.5 µg/ml) and 3.7 (3.7-3.8 µg/ml), while those of the predicted plasma propofol concentration were 2.8 (2.7-2.9 µg/ml), 3.9 (3.8-3.9 µg/ml) and 4.9 (4.8-5.0 µg/ml), respectively. The values of BIS, SE and RE were 62, 59 and 63 when 50% of patients lost consciousness, and 79, 80, 85 and 42, 37, 44, respectively, when 5% and 95% of patients were unconscious. The values of BIS, RE and SE dropped two minutes after the injection of muscle relaxant, but there were no significant differences between RE and SE. MAP and HR increased visibly, which indicated a reaction to tracheal intubation; the values of BIS, RE and SE, however, did not display any significant changes. This large-sample multicentric study confirmed the values of RE and SE as approximating BIS value, at the onset of unconsciousness during propofol TCI anesthesia. After elimination of myoelectrical activation, all values of RE, SE and BIS decreased significantly and the three indices were less sensitive to noxious stimuli than cardiovascular responses.

Response surface modeling of alfentanil-sevoflurane interaction on cardiorespiratory control and bispectral index.

PubMed

Dahan, A; Nieuwenhuijs, D; Olofsen, E; Sarton, E; Romberg, R; Teppema, L

2001-06-01

Respiratory depression is a serious side effect of anesthetics and opioids. The authors examined the influence of the combined administration of sevoflurane and alfentanil on ventilatory control, heart rate (HR), and Bispectral Index (BIS) in healthy volunteers. Step decreases in end-tidal partial pressure of oxygen from normoxia into hypoxia (approximately 50 mmHg) at constant end-tidal partial pressure of carbon dioxide (approximately 48 mmHg) were performed in nine male volunteers at various concentrations of alfentanil and sevoflurane, ranging from 0 to 50 ng/ml for alfentanil and from 0 to 0.4 end-tidal concentration (ET%) for sevoflurane, and with various combinations of alfentanil and sevoflurane. The alfentanil-sevoflurane interactions on normoxic resting (hypercapnic) ventilation (Vi), HR, hypoxic Vi, and HR responses and BIS were assessed by construction of response surfaces that related alfentanil and sevoflurane to effect using a population analysis. Concentration-effect relations were linear for alfentanil and sevoflurane. Synergistic interactions were observed for resting Vi and resting HR. Depression of Vi by 25% occurred at 38 +/- 11 ng/ml alfentanil (population mean +/- SE) and at 0.7 +/- 0.4 ET% sevoflurane. One possibility for 25% reduction when alfentanil and sevoflurane are combined is 13.4 ng/ml alfentanil plus 0.12 ET% sevoflurane. Additive interactions were observed for hypoxic Vi and HR responses and BIS. Depression of the hypoxic Vi response by 25% occurred at 16 +/- 1 ng/ml alfentanil and 0.14 +/- 0.05 ET% sevoflurane. The effect of sevoflurane on the BIS (25% reduction of BIS occurred at 0.45 +/- 0.08 ET%) was independent of the alfentanil concentration. Response surface modeling was used successfully to analyze the effect of interactions between two drugs on respiration. The combination of alfentanil and sevoflurane causes more depression of Vi and HR than does the summed effect of each drug administered separately. The effects of combining alfentanil and sevoflurane on hypoxic Vi and HR responses and BIS could be predicted from the separate dose-response curves. Over the dose range tested, the hypoxic response is more sensitive to the effects of anesthetics and opioids relative to resting ventilation.

Monitoring sleep depth: analysis of bispectral index (BIS) based on polysomnographic recordings and sleep deprivation.

PubMed

Giménez, Sandra; Romero, Sergio; Alonso, Joan Francesc; Mañanas, Miguel Ángel; Pujol, Anna; Baxarias, Pilar; Antonijoan, Rosa Maria

2017-02-01

The assessment and management of sleep are increasingly recommended in the clinical practice. Polysomnography (PSG) is considered the gold standard test to monitor sleep objectively, but some practical and technical constraints exist due to environmental and patient considerations. Bispectral index (BIS) monitoring is commonly used in clinical practice for guiding anesthetic administration and provides an index based on relationships between EEG components. Due to similarities in EEG synchronization between anesthesia and sleep, several studies have assessed BIS as a sleep monitor with contradictory results. The aim of this study was to evaluate objectively both the feasibility and reliability of BIS for sleep monitoring through a robust methodology, which included full PSG recordings at a baseline situation and after 40 h of sleep deprivation. Results confirmed that the BIS index was highly correlated with the hypnogram (0.89 ± 0.02), showing a progressive decrease as sleep deepened, and an increase during REM sleep (awake: 91.77 ± 8.42; stage N1: 83.95 ± 11.05; stage N2: 71.71 ± 11.99; stage N3: 42.41 ± 9.14; REM: 80.11 ± 8.73). Mean and median BIS values were lower in the post-deprivation night than in the baseline night, showing statistical differences for the slow wave sleep (baseline: 42.41 ± 9.14 vs. post-deprivation: 39.49 ± 10.27; p = 0.02). BIS scores were able to discriminate properly between deep (N3) and light (N1, N2) sleep. BIS values during REM overlapped those of other sleep stages, although EMG activity provided by the BIS monitor could help to identify REM sleep if needed. In conclusion, BIS monitors could provide a useful measure of sleep depth in especially particular situations such as intensive care units, and they could be used as an alternative for sleep monitoring in order to reduce PSG-derived costs and to increase capacity in ambulatory care.

Detection, monitoring, and quantitative analysis of wildfires with the BIRD satellite

NASA Astrophysics Data System (ADS)

Oertel, Dieter A.; Briess, Klaus; Lorenz, Eckehard; Skrbek, Wolfgang; Zhukov, Boris

2004-02-01

Increasing concern about environment and interest to avoid losses led to growing demands on space borne fire detection, monitoring and quantitative parameter estimation of wildfires. The global change research community intends to quantify the amount of gaseous and particulate matter emitted from vegetation fires, peat fires and coal seam fires. The DLR Institute of Space Sensor Technology and Planetary Exploration (Berlin-Adlershof) developed a small satellite called BIRD (Bi-spectral Infrared Detection) which carries a sensor package specially designed for fire detection. BIRD was launched as a piggy-back satellite on October 22, 2001 with ISRO"s Polar Satellite Launch Vehicle (PSLV). It is circling the Earth on a polar and sun-synchronous orbit at an altitude of 572 km and it is providing unique data for detailed analysis of high temperature events on Earth surface. The BIRD sensor package is dedicated for high resolution and reliable fire recognition. Active fire analysis is possible in the sub-pixel domain. The leading channel for fire detection and monitoring is the MIR channel at 3.8 μm. The rejection of false alarms is based on procedures using MIR/NIR (Middle Infra Red/Near Infra Red) and MIR/TIR (Middle Infra Red/Thermal Infra Red) radiance ratio thresholds. Unique results of BIRD wildfire detection and analysis over fire prone regions in Australia and Asia will be presented. BIRD successfully demonstrates innovative fire recognition technology for small satellites which permit to retrieve quantitative characteristics of active burning wildfires, such as the equivalent fire temperature, fire area, radiative energy release, fire front length and fire front strength.

Comparing multiple turbulence restoration algorithms performance on noisy anisoplanatic imagery

NASA Astrophysics Data System (ADS)

Rucci, Michael A.; Hardie, Russell C.; Dapore, Alexander J.

2017-05-01

In this paper, we compare the performance of multiple turbulence mitigation algorithms to restore imagery degraded by atmospheric turbulence and camera noise. In order to quantify and compare algorithm performance, imaging scenes were simulated by applying noise and varying levels of turbulence. For the simulation, a Monte-Carlo wave optics approach is used to simulate the spatially and temporally varying turbulence in an image sequence. A Poisson-Gaussian noise mixture model is then used to add noise to the observed turbulence image set. These degraded image sets are processed with three separate restoration algorithms: Lucky Look imaging, bispectral speckle imaging, and a block matching method with restoration filter. These algorithms were chosen because they incorporate different approaches and processing techniques. The results quantitatively show how well the algorithms are able to restore the simulated degraded imagery.

The AAI index, the BIS index and end-tidal concentration during wash in and wash out of sevoflurane.

PubMed

Anderson, R E; Barr, G; Assareh, H; Jakobsson, J

2003-06-01

The bispectral index (BIS), auditory evoked potential index (AAI) and the end-tidal sevoflurane concentration were studied during induction and emergence in 10 ASA I-II patients. Both during 'wash-in' and 'wash-out' of sevoflurane, the AAI and BIS indices show huge variability and an overlap of indices between awake and not responding to command. This was the most pronounced during induction and the range of values was larger for the AAI index as compared with the BIS index. Mean (range) BIS was 85 (73-98) and 48 (10-83) awake and unconscious, respectively, and mean AAI index was 71 (43-99) and 21 (4-85), respectively. This study demonstrates the difficulties of using processed EEG variables in real time in a clinical situation of non-steady state pharmacodynamics.

Resumes of the Bird mission

NASA Astrophysics Data System (ADS)

Lorenz, E.; Borwald, W.; Briess, K.; Kayal, H.; Schneller, M.; Wuensten, Herbert

2004-11-01

The DLR micro satellite BIRD (Bi-spectral Infra Red Detection) was piggy- back launched with the Indian Polar Satellite Launch Vehicle PSLV-C3 into a 570 km circular sun-synchronous orbit on 22 October 2001. The BIRD mission, fully funded by the DLR, answers topical technological and scientific questions related to the operation of a compact infra- red push-broom sensor system on board of a micro satellite and demonstrates new spacecraft bus technologies. BIRD mission control is conducted by DLR / GSOC in Oberpfaffenhofen. Commanding, data reception and data processing is performed via ground stations in Weilheim and Neustrelitz (Germany). The BIRD mission is a demonstrator for small satellite projects dedicated to the hazard detection and monitoring. In the year 2003 BIRD has been used in the ESA project FUEGOSAT to demonstrate the utilisation of innovative space technologies for fire risk management.

Comparison of modeled estimates of inhalation exposure to aerosols during use of consumer spray products.

PubMed

Park, Jihoon; Yoon, Chungsik; Lee, Kiyoung

2018-05-30

In the field of exposure science, various exposure assessment models have been developed to complement experimental measurements; however, few studies have been published on their validity. This study compares the estimated inhaled aerosol doses of several inhalation exposure models to experimental measurements of aerosols released from consumer spray products, and then compares deposited doses within different parts of the human respiratory tract according to deposition models. Exposure models, including the European Center for Ecotoxicology of Chemicals Targeted Risk Assessment (ECETOC TRA), the Consumer Exposure Model (CEM), SprayExpo, ConsExpo Web and ConsExpo Nano, were used to estimate the inhaled dose under various exposure scenarios, and modeled and experimental estimates were compared. The deposited dose in different respiratory regions was estimated using the International Commission on Radiological Protection model and multiple-path particle dosimetry models under the assumption of polydispersed particles. The modeled estimates of the inhaled doses were accurate in the short term, i.e., within 10 min of the initial spraying, with a differences from experimental estimates ranging from 0 to 73% among the models. However, the estimates for long-term exposure, i.e., exposure times of several hours, deviated significantly from the experimental estimates in the absence of ventilation. The differences between the experimental and modeled estimates of particle number and surface area were constant over time under ventilated conditions. ConsExpo Nano, as a nano-scale model, showed stable estimates of short-term exposure, with a difference from the experimental estimates of less than 60% for all metrics. The deposited particle estimates were similar among the deposition models, particularly in the nanoparticle range for the head airway and alveolar regions. In conclusion, the results showed that the inhalation exposure models tested in this study are suitable for estimating short-term aerosol exposure (within half an hour), but not for estimating long-term exposure. Copyright © 2018 Elsevier GmbH. All rights reserved.

Electroencephalographic response following midazolam-induced general anesthesia: relationship to plasma and effect-site midazolam concentrations.

PubMed

Miyake, Wakako; Oda, Yutaka; Ikeda, Yuko; Hagihira, Satoshi; Iwaki, Hiroyoshi; Asada, Akira

2010-06-01

To examine the relationships between effect-site concentrations and electroencephalographic parameters after the induction of general anesthesia with midazolam. Twenty-four patients with American Society of Anesthesiologists status I or II were randomly allocated to receive either an intravenous (i.v.) bolus of midazolam 0.2 mg kg(-1) (small-dose group, n = 12) or 0.3 mg kg(-1) (large-dose group, n = 12) for induction of general anesthesia in a double-blind experimental design. The bispectral index (BIS), 95% spectral edge frequency (SEF95), spectral power density, and plasma concentrations of midazolam were measured for 60 min following the induction of general anesthesia. Plasma and simulated effect-site concentrations of midazolam were significantly higher in the large-dose group than in the small-dose group (P = 0.005 and <0.001, respectively). There was a correlation between the relative beta ratio and BIS (r (2) = 0.30, P < 0.001; n = 168); however, effect-site concentrations of midazolam showed no association with BIS, relative beta ratio, or SEF95 (r (2) = 0.07, 0.11 and 0.01, respectively; n = 168). The electroencephalographic spectral power density in the beta-band (>/=13 and <30 Hz) was significantly increased after induction and was significantly larger in the large-dose group than in the small-dose group (P = 0.009). Following the induction of general anesthesia with i.v. midazolam 0.2 or 0.3 mg kg(-1), the BIS was positively correlated with the relative beta ratio. Despite a rapid decrease in the plasma and effect-site concentrations of midazolam, the average BIS remained >60 for 60 min after induction, reflecting an increased power of the electroencephalographic high-frequency band.

Computer-assisted propofol administration.

PubMed

O'Connor, J P A; O'Moráin, C A; Vargo, J J

2010-01-01

The use of propofol for sedation in endoscopy may allow for better quality of sedation, quicker recovery and facilitate greater throughput in endoscopy units. The cost-effectiveness and utility of propofol sedation for endoscopic procedures is contingent on the personnel and resources required to carry out the procedure. Computer-based platforms are based on the patients response to stimulation and physiologic parameters. They offer an appealing means of delivering safe and effective doses of propofol. One such means is the bispectral index where continuous EEG recordings are used to assess the degree of sedation. Another is the closed-loop target-controlled system where a set of physical parameters, such as muscle relaxation and auditory-evoked potential, determine a level of medication appropriate to achieve sedation. Patient-controlled platforms may also be used. These electronic adjuncts may help endoscopists who wish to adopt propofol sedation to change current practices with greater confidence. Copyright 2010 S. Karger AG, Basel.

Nonlinear dynamics of the patient’s response to drug effect during general anesthesia

NASA Astrophysics Data System (ADS)

Ionescu, Clara; Tenreiro Machado, Jose; De Keyser, Robin; Decruyenaere, Johan; Struys, Michel M. R. F.

2015-03-01

In today's healthcare paradigm, optimal sedation during anesthesia plays an important role both in patient welfare and in the socio-economic context. For the closed-loop control of general anesthesia, two drugs have proven to have stable, rapid onset times: propofol and remifentanil. These drugs are related to their effect in the bispectral index, a measure of EEG signal. In this paper wavelet time-frequency analysis is used to extract useful information from the clinical signals, since they are time-varying and mark important changes in patient's response to drug dose. Model based predictive control algorithms are employed to regulate the depth of sedation by manipulating these two drugs. The results of identification from real data and the simulation of the closed loop control performance suggest that the proposed approach can bring an improvement of 9% in overall robustness and may be suitable for clinical practice.

[Helicopter transportation of a sedated, mechanically ventilated patient with cervical cord injury].

PubMed

Kato, Hideya; Nishiwaki, Yuko; Hosoi, Kunihiko; Shiomi, Naoto; Hirata, Masashi

2013-09-01

We report helicopter transportation of a sedated, mechanically ventilated patient with cervical cord injury. A 20-year-old male sustained traumatic injury to the cervical spinal cord during extracurricular activities in a college. On arrival at the hospital, a halo vest was placed on the patient and tracheostomy was performed. On the 38th hospital day, he was transported a distance of 520km by helicopter to a specialized hospital in Fukuoka for medical repatriation. Cabin space was narrow. Since power supply and carrying capacity were limited, battery-driven and portable medical devices were used. In consideration for patient's psychological stress, he was sedated with propofol. RSS (Ramsay sedation scale) scores were recorded to evaluate whether the patient was adequately sedated during helicopter transportation. Prior to transport, we rehearsed the sedation using bispectral index monitoring (BIS) in the hospital to further ensure the patient's safety during the transport.

Uncertainties in Cloud Phase and Optical Thickness Retrievals from the Earth Polychromatic Imaging Camera (EPIC)

NASA Technical Reports Server (NTRS)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud-temperature-threshold-based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (less than 2 percent) due to the particle- size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10 percent, although for thin clouds (COT less than 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

PubMed Central

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2018-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study. PMID:29619116

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC).

PubMed

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-01-01

This paper presents an investigation of the expected uncertainties of a single channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud temperature threshold based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODIS daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single channel COT retrieval is feasible for EPIC. For ice clouds, single channel retrieval errors are minimal (< 2%) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10%, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Time-varying bispectral analysis of visually evoked multi-channel EEG

NASA Astrophysics Data System (ADS)

Chandran, Vinod

2012-12-01

Theoretical foundations of higher order spectral analysis are revisited to examine the use of time-varying bicoherence on non-stationary signals using a classical short-time Fourier approach. A methodology is developed to apply this to evoked EEG responses where a stimulus-locked time reference is available. Short-time windowed ensembles of the response at the same offset from the reference are considered as ergodic cyclostationary processes within a non-stationary random process. Bicoherence can be estimated reliably with known levels at which it is significantly different from zero and can be tracked as a function of offset from the stimulus. When this methodology is applied to multi-channel EEG, it is possible to obtain information about phase synchronization at different regions of the brain as the neural response develops. The methodology is applied to analyze evoked EEG response to flash visual stimulii to the left and right eye separately. The EEG electrode array is segmented based on bicoherence evolution with time using the mean absolute difference as a measure of dissimilarity. Segment maps confirm the importance of the occipital region in visual processing and demonstrate a link between the frontal and occipital regions during the response. Maps are constructed using bicoherence at bifrequencies that include the alpha band frequency of 8Hz as well as 4 and 20Hz. Differences are observed between responses from the left eye and the right eye, and also between subjects. The methodology shows potential as a neurological functional imaging technique that can be further developed for diagnosis and monitoring using scalp EEG which is less invasive and less expensive than magnetic resonance imaging.

Effects of Single Low Dose of Dexamethasone before Noncardiac and Nonneurologic Surgery and General Anesthesia on Postoperative Cognitive Dysfunction—A Phase III Double Blind, Randomized Clinical Trial

PubMed Central

Pereira, Valeria Fontenelle Angelim; Pietrobon, Ricardo S.; Schmidt, Andre P.; Oses, Jean P.; Portela, Luis V.; Souza, Diogo O.; Vissoci, João Ricardo Nickenig; da Luz, Vinicius Fernando; Trintoni, Leticia Maria de Araujo de Souza; Nielsen, Karen C.; Carmona, Maria José Carvalho

2016-01-01

Postoperative cognitive dysfunction (POCD) is a multifactorial adverse event most frequently in elderly patients. This study evaluated the effect of dexamethasone on POCD incidence after noncardiac and nonneurologic surgery. METHODS: One hundred and forty patients (ASA I-II; age 60–87 years) took part in a prospective phase III, double blind, randomized study involving the administration or not of 8 mg of IV dexamethasone before general anesthesia under bispectral index (BIS) between 35–45 or 46–55. Neuropsychological tests were applied preoperatively and on the 3rd, 7th, 21st, 90th and 180th days after surgery and compared with normative data. S100β was evaluated before and 12 hours after induction of anesthesia. The generalized estimating equations (GEE) method was applied, followed by the posthoc Bonferroni test considering P<0.05 as significant. RESULTS: On the 3rd postoperative day, POCD was diagnosed in 25.2% and 15.3% of patients receiving dexamethasone, BIS 35–45, and BIS 46–55 groups, respectively. Meanwhile, POCD was present in 68.2% and 27.2% of patients without dexamethasone, BIS 35–45 and BIS 46–55 groups (p<0.0001). Neuropsychological tests showed that dexamethasone associated to BIS 46–55 decreased the incidence of POCD, especially memory and executive function. The administration of dexamethasone might have prevented the postoperative increase in S100β serum levels. CONCLUSION: Dexamethasone can reduce the incidence of POCD in elderly patients undergoing surgery, especially when associated with BIS 46–55. The effect of dexamethasone on S100β might be related with some degree of neuroprotection. Trial Registration: www.clinicaltrials.gov NCT01332812 PMID:27152422

Influence of Depth of Hypnosis on Pupillary Reactivity to a Standardized Tetanic Stimulus in Patients Under Propofol-Remifentanil Target-Controlled Infusion: A Crossover Randomized Pilot Study.

PubMed

Sabourdin, Nada; Peretout, Jean-Baptiste; Khalil, Eliane; Guye, Marie-Laurence; Louvet, Nicolas; Constant, Isabelle

2018-01-01

Pupillometry allows the measurement of pupillary diameter variations in response to nociceptive stimuli. This technique has been used to monitor the balance between analgesia and nociception. Under general anesthesia, the amplitude of pupillary dilation is related to the amount of administered opioids. The objective of this study was to determine whether at a constant infusion rate of opioids, the pupillary response was influenced by depth of hypnosis assessed by the bispectral index (BIS). Twelve patients (14-20 years) anesthetized for orthopedic surgery were included. Under propofol-remifentanil target-controlled infusion, remifentanil effect site target concentration was fixed at 1 ng/mL. Two measures of pupillary reflex dilation were performed on each patient in a randomized order: one at BIS 55 and one at BIS 25. These levels of BIS were obtained by adjusting propofol target concentration and maintained for 10 minutes before each measure. For each measure, we applied a standardized tetanic stimulation on the patient's forearm (60 mA, 100 Hz, 5 seconds). All measures were performed before the beginning of surgery. Pupillary dilation was significantly greater at BIS 55 than at BIS 25: 32.1% ± 5.3% vs 10.4% ± 2.5% (mean difference estimate [95% confidence interval]: 21.8% [12.9-30.6], P < .001), without carryover effect (P = .30) nor period effect (P = .52). Hemodynamic parameters and BIS were not modified by the stimulation. In patients receiving a constant infusion of remifentanil at a target concentration of 1 ng/mL, pupillary dilation after a standardized tetanic stimulation was influenced by depth of hypnosis assessed by the BIS.

A 3-Year Climatology of Cloud and Radiative Properties Derived from GOES-8 Data Over the Southern Great Plains

NASA Technical Reports Server (NTRS)

Khaiyer, M. M.; Rapp, A. D.; Doelling, D. R.; Nordeen, M. L.; Minnis, P.; Smith, W. L., Jr.; Nguyen, L.

2001-01-01

While the various instruments maintained at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility (CF) provide detailed cloud and radiation measurements for a small area, satellite cloud property retrievals provide a means of examining the large-scale properties of the surrounding region over an extended period of time. Seasonal and inter-annual climatological trends can be analyzed with such a dataset. For this purpose, monthly datasets of cloud and radiative properties from December 1996 through November 1999 over the SGP region have been derived using the layered bispectral threshold method (LBTM). The properties derived include cloud optical depths (ODs), temperatures and albedos, and are produced on two grids of lower (0.5 deg) and higher resolution (0.3 deg) centered on the ARM SGP CF. The extensive time period and high-resolution of the inner grid of this dataset allows for comparison with the suite of instruments located at the ARM CF. In particular, Whole-Sky Imager (WSI) and the Active Remote Sensing of Clouds (ARSCL) cloud products can be compared to the cloud amounts and heights of the LBTM 0.3 deg grid box encompassing the CF site. The WSI provides cloud fraction and the ARSCL computes cloud fraction, base, and top heights using the algorithms by Clothiaux et al. (2001) with a combination of Belfort Laser Ceilometer (BLC), Millimeter Wave Cloud Radar (MMCR), and Micropulse Lidar (MPL) data. This paper summarizes the results of the LBTM analysis for 3 years of GOES-8 data over the SGP and examines the differences between surface and satellite-based estimates of cloud fraction.

Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)

NASA Astrophysics Data System (ADS)

Meyer, Kerry; Yang, Yuekui; Platnick, Steven

2016-04-01

This paper presents an investigation of the expected uncertainties of a single-channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud-temperature-threshold-based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC Sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single-channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single-channel COT retrieval is feasible for EPIC. For ice clouds, single-channel retrieval errors are minimal (< 2 %) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10 %, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study.

Experimental Demonstration of a Cheap and Accurate Phase Estimation

DOE PAGES

Rudinger, Kenneth; Kimmel, Shelby; Lobser, Daniel; ...

2017-05-11

We demonstrate an experimental implementation of robust phase estimation (RPE) to learn the phase of a single-qubit rotation on a trapped Yb + ion qubit. Here, we show this phase can be estimated with an uncertainty below 4 × 10 -4 rad using as few as 176 total experimental samples, and our estimates exhibit Heisenberg scaling. Unlike standard phase estimation protocols, RPE neither assumes perfect state preparation and measurement, nor requires access to ancillae. We crossvalidate the results of RPE with the more resource-intensive protocol of gate set tomography.

Feasibility of closed-loop co-administration of propofol and remifentanil guided by the bispectral index in obese patients: a prospective cohort comparison.

PubMed

Liu, N; Lory, C; Assenzo, V; Cocard, V; Chazot, T; Le Guen, M; Sessler, D I; Journois, D; Fischler, M

2015-04-01

We used an automated bispectral index (BIS)-guided dual-loop controller to determine propofol and remifentanil requirements during general anaesthesia in obese and lean surgical patients. Obese patients, BMI>35 kg m(-2), and lean patients (<25 kg m(-2)) having laparoscopic procedures were prospectively evaluated in this multicentre single-blind study. The automated controller targeted BIS between 40 and 60 by adjusting propofol and remifentanil administration. Propofol and remifentanil consumptions were calculated using both total body weight (TBW) and ideal body weight (IBW). Results are expressed as medians (inter-quartile range). Thirty obese [BMI=43 (40-49) kg m(-2)] and 29 lean [BMI=23 (21-25) kg m(-2)] patients completed the study. BIS was between 40 and 60 during 84 (69-91)% vs 85 (78-92)% of the anaesthetic time, P=0.46. The amount of propofol given during induction [1.2 (1.1-1.6) vs 1.3 (1.0-1.7) mg kg(-1), P=0.47] and maintenance [5.2 (4.1-6) vs 5.3 (4.7-6.4) mg kg(-1) h(-1), P=0.39] calculated using TBW was similar between the two groups. The dual-loop controller delivered half as much remifentanil to the obese patients during induction [1.0 (0.8-1.6) vs 2.2 (1.5-2.7) µg kg(-1), P<0.001] and maintenance [0.12 (0.07-0.16) vs 0.25 (0.17-0.29) µg kg(-1) min(-1), P<0.001] calculated using TBW. But when remifentanil consumption was calculated using IBW, the amounts were similar during induction at 2.2 (1.6-3.5) vs 2.0 (1.6-3.0) µg kg(-1) IBW, P=0.48, and during maintenance at 0.26 (0.16-0.34) vs 0.27 (0.18-0.33 ) µg kg(-1) min(-1), P=0.50. The amount of propofol-remifentanil administered by the controller is consistent with current knowledge, propofol is best dosed using TBW whereas remifentanil is best dosed using IBW. NCT00779844. © 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.

[Effects of electroacupuncture on bispectral index and plasma beta-endorphin in patients undergoing colonoscopy].

PubMed

Ni, Yu-Fei; Li, Jun; Wang, Ben-Fu; Jiang, Song-He; Chen, Yi; Zhang, Wei-Feng; Lian, Qing-Quan

2009-10-01

To observe the effect of electroacupuncture (EA) on bispectral index (BIS) and plasma beta-endorphin (beta-EP) level in patients undergoing colonoscopy. Sixty patients were equally randomized into EA group and control group with 30 cases in each. EA (2 Hz/100 Hz, 4-6 V) was applied to the right Zusanli (ST 36) and Shangjuxu (ST 37), and the left Yinlingquan (SP 9), Sanyinjiao (SP 6) and bilateral Hegu (LI 4) respectively 30 min before colonoscopy. The mean arterial pressure (MAP), heart rate (HR) and BIS in two groups were continuously monitored during the study. Plasma beta-EP concentration was detected by radioimmunoassay. The patient's adverse reactions (including pain, satisfaction degree, etc.) were evaluated by visual analog scale (VAS) and verbal stress scale (VSS). Self-comparison showed that MAP and HR in control group increased significantly during colonoscope's splenic flexure passing (P<0.05). Whereas the 2 indexes in EA group had no significant changes during colonoscope insertion, and its splenic flexure passing, hepatic flexure passing and post-enteroscopy (P>0.05). Comparison between two groups showed that MAP at the time-point of colonoscope insertion, and HR at the time-point of colonoscope's splenic flexure passing in EA group were significantly lower than those in control group (P<0.05). BIS values of EA group were significantly lower than those of control group at different time-points after colonoscope insertion (P<0.01). Plasma beta-EP concentrations at the time-points of colonoscope's hepatic flexure passing and post-enteroscopy were evidently increased in both groups in comparison with pre-enteroscopy (P<0.01), and beta-EP was significantly lower in EA group than that in control group at the time-point of colonoscope's hepatic flexure passing (P<0.05). The dosage of Midazolam used for conscious-sedation and the scores of VAS and VSS were also considerably lower in EA group than those in control group (P<0.05, P<0.01). No significant differences were found between two groups in the adverse reactions as dizziness, nausea, vomiting and abdominal pain, but the patients' satisfaction degree in EA group was evidently higher than that in control group (P<0.05). Acupuncture analgesia can effectively lower the colonoscopy patients' BIS value and plasma beta-EP level, meaning attenuation of the patients' stress responses during colonoscopy after EA.

Sample entropy analysis for the estimating depth of anaesthesia through human EEG signal at different levels of unconsciousness during surgeries

PubMed Central

Fan, Shou-Zen; Abbod, Maysam F.

2018-01-01

Estimating the depth of anaesthesia (DoA) in operations has always been a challenging issue due to the underlying complexity of the brain mechanisms. Electroencephalogram (EEG) signals are undoubtedly the most widely used signals for measuring DoA. In this paper, a novel EEG-based index is proposed to evaluate DoA for 24 patients receiving general anaesthesia with different levels of unconsciousness. Sample Entropy (SampEn) algorithm was utilised in order to acquire the chaotic features of the signals. After calculating the SampEn from the EEG signals, Random Forest was utilised for developing learning regression models with Bispectral index (BIS) as the target. Correlation coefficient, mean absolute error, and area under the curve (AUC) were used to verify the perioperative performance of the proposed method. Validation comparisons with typical nonstationary signal analysis methods (i.e., recurrence analysis and permutation entropy) and regression methods (i.e., neural network and support vector machine) were conducted. To further verify the accuracy and validity of the proposed methodology, the data is divided into four unconsciousness-level groups on the basis of BIS levels. Subsequently, analysis of variance (ANOVA) was applied to the corresponding index (i.e., regression output). Results indicate that the correlation coefficient improved to 0.72 ± 0.09 after filtering and to 0.90 ± 0.05 after regression from the initial values of 0.51 ± 0.17. Similarly, the final mean absolute error dramatically declined to 5.22 ± 2.12. In addition, the ultimate AUC increased to 0.98 ± 0.02, and the ANOVA analysis indicates that each of the four groups of different anaesthetic levels demonstrated significant difference from the nearest levels. Furthermore, the Random Forest output was extensively linear in relation to BIS, thus with better DoA prediction accuracy. In conclusion, the proposed method provides a concrete basis for monitoring patients’ anaesthetic level during surgeries. PMID:29844970

Direction of Arrival Estimation Using a Reconfigurable Array

DTIC Science & Technology

2005-05-06

civilian world. Keywords: Direction-of-arrival Estimation MUSIC algorithm Reconfigurable Array Experimental Created by Neevia Personal...14. SUBJECT TERMS: Direction-of-arrival ; Estimation ; MUSIC algorithm ; Reconfigurable ; Array ; Experimental 16. PRICE CODE 17...9 1.5 MuSiC Algorithm

Plant Disease Severity Assessment-How Rater Bias, Assessment Method, and Experimental Design Affect Hypothesis Testing and Resource Use Efficiency.

PubMed

Chiang, Kuo-Szu; Bock, Clive H; Lee, I-Hsuan; El Jarroudi, Moussa; Delfosse, Philippe

2016-12-01

The effect of rater bias and assessment method on hypothesis testing was studied for representative experimental designs for plant disease assessment using balanced and unbalanced data sets. Data sets with the same number of replicate estimates for each of two treatments are termed "balanced" and those with unequal numbers of replicate estimates are termed "unbalanced". The three assessment methods considered were nearest percent estimates (NPEs), an amended 10% incremental scale, and the Horsfall-Barratt (H-B) scale. Estimates of severity of Septoria leaf blotch on leaves of winter wheat were used to develop distributions for a simulation model. The experimental designs are presented here in the context of simulation experiments which consider the optimal design for the number of specimens (individual units sampled) and the number of replicate estimates per specimen for a fixed total number of observations (total sample size for the treatments being compared). The criterion used to gauge each method was the power of the hypothesis test. As expected, at a given fixed number of observations, the balanced experimental designs invariably resulted in a higher power compared with the unbalanced designs at different disease severity means, mean differences, and variances. Based on these results, with unbiased estimates using NPE, the recommended number of replicate estimates taken per specimen is 2 (from a sample of specimens of at least 30), because this conserves resources. Furthermore, for biased estimates, an apparent difference in the power of the hypothesis test was observed between assessment methods and between experimental designs. Results indicated that, regardless of experimental design or rater bias, an amended 10% incremental scale has slightly less power compared with NPEs, and that the H-B scale is more likely than the others to cause a type II error. These results suggest that choice of assessment method, optimizing sample number and number of replicate estimates, and using a balanced experimental design are important criteria to consider to maximize the power of hypothesis tests for comparing treatments using disease severity estimates.

Speckle imaging with the MAMA detector: Preliminary results

NASA Technical Reports Server (NTRS)

Horch, E.; Heanue, J. F.; Morgan, J. S.; Timothy, J. G.

1994-01-01

We report on the first successful speckle imaging studies using the Stanford University speckle interferometry system, an instrument that uses a multianode microchannel array (MAMA) detector as the imaging device. The method of producing high-resolution images is based on the analysis of so-called 'near-axis' bispectral subplanes and follows the work of Lohmann et al. (1983). In order to improve the signal-to-noise ratio in the bispectrum, the frame-oversampling technique of Nakajima et al. (1989) is also employed. We present speckle imaging results of binary stars and other objects from V magnitude 5.5 to 11, and the quality of these images is studied. While the Stanford system is capable of good speckle imaging results, it is limited by the overall quantum efficiency of the current MAMA detector (which is due to the response of the photocathode at visible wavelengths and other detector properties) and by channel saturation of the microchannel plate. Both affect the signal-to-noise ratio of the power spectrum and bispectrum.

Positive state observer for the automatic control of the depth of anesthesia-Clinical results.

PubMed

Nogueira, Filipa N; Mendonça, T; Rocha, P

2016-09-13

The depth of anesthesia (DoA) is a crucial feature in general anesthesia. Nowadays the DoA is usually evaluated by the bispectral index (BIS). According to the surgical procedure, different reference levels for the BIS may be clinically required. This can be achieved by the simultaneous administration of an analgesic (e.g. remifentanil) and an hypnotic (eg propofol). As a contribution to the effort of automating the processes of drug delivery in general anesthesia, in this paper, a positive state observer is designed for the implementation of a control scheme proposed for the automatic administration of propofol and of remifentanil, in order to track a desired level for the BIS. It is proved and illustrated by simulations that the controller-observer scheme has a very good performance. This scheme was implemented, tested and evaluated both by means of simulations and for a set of patients during surgical procedures. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Processed electroencephalogram during donation after cardiac death.

PubMed

Auyong, David B; Klein, Stephen M; Gan, Tong J; Roche, Anthony M; Olson, Daiwai; Habib, Ashraf S

2010-05-01

We present a case series of increased bispectral index values during donation after cardiac death (DCD). During the DCD process, a patient was monitored with processed electroencephalogram (EEG), which showed considerable changes traditionally associated with lighter planes of anesthesia immediately after withdrawal of care. Subsequently, to validate the findings of this case, processed EEG was recorded during 2 other cases in which care was withdrawn without the use of hypnotic or anesthetic drugs. We found that changes in processed EEG immediately after withdrawal of care were not only reproducible, but can happen in the absence of changes in major electromyographic or electrocardiographic artifact. It is well documented that processed EEG is prone to artifacts. However, in the setting of DCD, these changes in processed EEG deserve some consideration. If these changes are not due to artifact, dosing of hypnotic or anesthetic drugs might be warranted. Use of these drugs during DCD based primarily on processed EEG values has never been addressed.

A cascade feedback control approach for hypnosis.

PubMed

Puebla, Hector; Alvarez-Ramírez, José

2005-10-01

This article studies the problem of controlling the drug administration during an anesthesia process, where muscle relaxation, analgesia, and hypnosis are regulated by means of monitored administration of specific drugs. On the basis of a seventh-order nonlinear pharmacokinetic-pharmacodynamic representation of the hypnosis process dynamics, a cascade (master/slave) feedback control structure for controlling the bispectral index (BIS) is proposed. The master controller compares the measured BIS with its reference value to provide the expired isoflurane concentration reference to the slave controller. In turn, the slave controller manipulates the anesthetic isoflurane concentration entering the anesthetic system to achieve the reference from the master controller. The advantage of the proposed cascade control structure with respect to its noncascade counterpart is that the former provides operation protection against BIS measurement failures. In fact, under a BIS measurement fault, the master control feedback is broken and the slave controller operates under a safe reference value. Extensive numerical simulations are used to illustrate the functioning of the proposed cascade control structure.

Intravenous Sedation with Low-Dose Dexmedetomidine: Its Potential for Use in Dentistry

PubMed Central

Ogawa, Sachie; Seino, Hiroaki; Ito, Hiroshi; Yamazaki, Shinya; Ganzberg, Steven; Kawaai, Hiroyoshi

2008-01-01

This study investigated the physiologic and sedative parameters associated with a low-dose infusion of dexmedetomidine (Dex). Thirteen healthy volunteers were sedated with Dex at a loading dose of 6 mcg/kg/h for 5 minutes and a continuous infusion dose of 0.2 mcg/kg/h for 25 minutes. The recovery process was observed for 60 minutes post infusion. The tidal volume decreased significantly despite nonsignificant changes in respiratory rate, minute ventilation, oxygen saturation, and end-tidal carbon dioxide. The mean arterial pressure and heart rate also decreased significantly but within clinically acceptable levels. Amnesia to pin prick was present in 69% of subjects. A Trieger dot test plot error ratio did not show a significant change at 30 minutes post infusion despite a continued significant decrease in bispectral index. We conclude that sedation with a low dose of Dex appears to be safe and potentially efficacious for young healthy patients undergoing dental procedures. PMID:18788843

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genest, Vincent X.; Vinet, Luc; Zhedanov, Alexei

The algebra H of the dual -1 Hahn polynomials is derived and shown to arise in the Clebsch-Gordan problem of sl{sub -1}(2). The dual -1 Hahn polynomials are the bispectral polynomials of a discrete argument obtained from the q{yields}-1 limit of the dual q-Hahn polynomials. The Hopf algebra sl{sub -1}(2) has four generators including an involution, it is also a q{yields}-1 limit of the quantum algebra sl{sub q}(2) and furthermore, the dynamical algebra of the parabose oscillator. The algebra H, a two-parameter generalization of u(2) with an involution as additional generator, is first derived from the recurrence relation of themore » -1 Hahn polynomials. It is then shown that H can be realized in terms of the generators of two added sl{sub -1}(2) algebras, so that the Clebsch-Gordan coefficients of sl{sub -1}(2) are dual -1 Hahn polynomials. An irreducible representation of H involving five-diagonal matrices and connected to the difference equation of the dual -1 Hahn polynomials is constructed.« less

Global Single and Multiple Cloud Classification with a Fuzzy Logic Expert System

NASA Technical Reports Server (NTRS)

Welch, Ronald M.; Tovinkere, Vasanth; Titlow, James; Baum, Bryan A.

1996-01-01

An unresolved problem in remote sensing concerns the analysis of satellite imagery containing both single and multiple cloud layers. While cloud parameterizations are very important both in global climate models and in studies of the Earth's radiation budget, most cloud retrieval schemes, such as the bispectral method used by the International Satellite Cloud Climatology Project (ISCCP), have no way of determining whether overlapping cloud layers exist in any group of satellite pixels. Coakley (1983) used a spatial coherence method to determine whether a region contained more than one cloud layer. Baum et al. (1995) developed a scheme for detection and analysis of daytime multiple cloud layers using merged AVHRR (Advanced Very High Resolution Radiometer) and HIRS (High-resolution Infrared Radiometer Sounder) data collected during the First ISCCP Regional Experiment (FIRE) Cirrus 2 field campaign. Baum et al. (1995) explored the use of a cloud classification technique based on AVHRR data. This study examines the feasibility of applying the cloud classifier to global satellite imagery.

Cardiorespiratory and antinociceptive effects of two different doses of lidocaine administered to horses during a constant intravenous infusion of xylazine and ketamine

PubMed Central

2013-01-01

Background This study investigated the antinociceptive effects of a constant rate infusion (CRI) of lidocaine during xylazine and ketamine anesthesia in horses and aimed to correlate these effects with cardiorespiratory variables, bispectral index (BIS) and plasma lidocaine concentrations. Six adult crossbred mares weighing 320–400 kg were anesthetized on three different occasions. Sedation was performed with xylazine (0.75 mg/kg IV) and anesthetic induction with guaifenesin (75 mg/kg IV) and ketamine (2 mg/kg IV). Anesthesia was maintained with 37.5 μg/kg/min of xylazine and 87.5 μg/kg/min of ketamine both administered intravenously for 75 min. The three treatments consisted of: lidocaine (loading dose: 5 mg/kg, CRI: 100 μg/kg/min; THL); lidocaine (loading dose: 2.5 mg/kg; CRI: 50 μg/kg/min: TLL); and saline (TS); all given 15 min after induction and maintained for 1 h. Antinociception was measured by response to electrical stimulation and bispectral index (BIS) was recorded during anesthesia. Parametric and non-parametric data were compared using ANOVA followed by Student-Newman-Keuls and Friedman tests, respectively. Results Plasma lidocaine concentrations peaked at the end of lidocaine loading dose and was greater in THL (9.61 ± 2.75 μg/mL) vs TLL (4.50 ± 3.34 μg/mL). Electrical noxious stimulation caused purposeful movement in all horses from TS, but no response in THL. The BIS was decreased in THL only and was less when compared to the other treatments throughout anesthesia. Blood pressure, PaO2 and PaCO2 increased and heart rate (HR), respiratory rate (RR), pH, total plasma protein and temperature decreased during anesthesia in all treatments. PaCO2 and HR were greater and RR and pH less in THL compared to TLL and TS at 30 min during anesthesia. All recoveries were considered excellent. Time to standing was longer after THL (60 ± 20 min) than following TLL and TS (32 ± 17 and 30 ± 15 min, respectively). Conclusions At the highest dose administered (THL) lidocaine CRI during xylazine/ketamine anesthesia decreased BIS and motor response to noxious stimulation, and prolonged recovery time without significant added cardiorespiratory depression. PMID:24103634

Differences between state entropy and bispectral index during analysis of identical electroencephalogram signals: a comparison with two randomised anaesthetic techniques.

PubMed

Pilge, Stefanie; Kreuzer, Matthias; Karatchiviev, Veliko; Kochs, Eberhard F; Malcharek, Michael; Schneider, Gerhard

2015-05-01

It is claimed that bispectral index (BIS) and state entropy reflect an identical clinical spectrum, the hypnotic component of anaesthesia. So far, it is not known to what extent different devices display similar index values while processing identical electroencephalogram (EEG) signals. To compare BIS and state entropy during analysis of identical EEG data. Inspection of raw EEG input to detect potential causes of erroneous index calculation. Offline re-analysis of EEG data from a randomised, single-centre controlled trial using the Entropy Module and an Aspect A-2000 monitor. Klinikum rechts der Isar, Technische Universität München, Munich. Forty adult patients undergoing elective surgery under general anaesthesia. Blocked randomisation of 20 patients per anaesthetic group (sevoflurane/remifentanil or propofol/remifentanil). Isolated forearm technique for differentiation between consciousness and unconsciousness. Prediction probability (PK) of state entropy to discriminate consciousness from unconsciousness. Correlation and agreement between state entropy and BIS from deep to light hypnosis. Analysis of raw EEG compared with index values that are in conflict with clinical examination, with frequency measures (frequency bands/Spectral Edge Frequency 95) and visual inspection for physiological EEG patterns (e.g. beta or delta arousal), pathophysiological features such as high-frequency signals (electromyogram/high-frequency EEG or eye fluttering/saccades), different types of electro-oculogram or epileptiform EEG and technical artefacts. PK of state entropy was 0.80 and of BIS 0.84; correlation coefficient of state entropy with BIS 0.78. Nine percent BIS and 14% state entropy values disagreed with clinical examination. Highest incidence of disagreement occurred after state transitions, in particular for state entropy after loss of consciousness during sevoflurane anaesthesia. EEG sequences which led to false 'conscious' index values often showed high-frequency signals and eye blinks. High-frequency EEG/electromyogram signals were pooled because a separation into EEG and fast electro-oculogram, for example eye fluttering or saccades, on the basis of a single EEG channel may not be very reliable. These signals led to higher Spectral Edge Frequency 95 and ratio of relative beta and gamma band power than EEG signals, indicating adequate unconscious classification. The frequency of other artefacts that were assignable, for example technical artefacts, movement artefacts, was negligible and they were excluded from analysis. High-frequency signals and eye blinks may account for index values that falsely indicate consciousness. Compared with BIS, state entropy showed more false classifications of the clinical state at transition between consciousness and unconsciousness.

Monitoring sedation status over time in ICU patients: reliability and validity of the Richmond Agitation-Sedation Scale (RASS).

PubMed

Ely, E Wesley; Truman, Brenda; Shintani, Ayumi; Thomason, Jason W W; Wheeler, Arthur P; Gordon, Sharon; Francis, Joseph; Speroff, Theodore; Gautam, Shiva; Margolin, Richard; Sessler, Curtis N; Dittus, Robert S; Bernard, Gordon R

2003-06-11

Goal-directed delivery of sedative and analgesic medications is recommended as standard care in intensive care units (ICUs) because of the impact these medications have on ventilator weaning and ICU length of stay, but few of the available sedation scales have been appropriately tested for reliability and validity. To test the reliability and validity of the Richmond Agitation-Sedation Scale (RASS). Prospective cohort study. Adult medical and coronary ICUs of a university-based medical center. Thirty-eight medical ICU patients enrolled for reliability testing (46% receiving mechanical ventilation) from July 21, 1999, to September 7, 1999, and an independent cohort of 275 patients receiving mechanical ventilation were enrolled for validity testing from February 1, 2000, to May 3, 2001. Interrater reliability of the RASS, Glasgow Coma Scale (GCS), and Ramsay Scale (RS); validity of the RASS correlated with reference standard ratings, assessments of content of consciousness, GCS scores, doses of sedatives and analgesics, and bispectral electroencephalography. In 290-paired observations by nurses, results of both the RASS and RS demonstrated excellent interrater reliability (weighted kappa, 0.91 and 0.94, respectively), which were both superior to the GCS (weighted kappa, 0.64; P<.001 for both comparisons). Criterion validity was tested in 411-paired observations in the first 96 patients of the validation cohort, in whom the RASS showed significant differences between levels of consciousness (P<.001 for all) and correctly identified fluctuations within patients over time (P<.001). In addition, 5 methods were used to test the construct validity of the RASS, including correlation with an attention screening examination (r = 0.78, P<.001), GCS scores (r = 0.91, P<.001), quantity of different psychoactive medication dosages 8 hours prior to assessment (eg, lorazepam: r = - 0.31, P<.001), successful extubation (P =.07), and bispectral electroencephalography (r = 0.63, P<.001). Face validity was demonstrated via a survey of 26 critical care nurses, which the results showed that 92% agreed or strongly agreed with the RASS scoring scheme, and 81% agreed or strongly agreed that the instrument provided a consensus for goal-directed delivery of medications. The RASS demonstrated excellent interrater reliability and criterion, construct, and face validity. This is the first sedation scale to be validated for its ability to detect changes in sedation status over consecutive days of ICU care, against constructs of level of consciousness and delirium, and correlated with the administered dose of sedative and analgesic medications.

Experimental demonstration of cheap and accurate phase estimation

NASA Astrophysics Data System (ADS)

Rudinger, Kenneth; Kimmel, Shelby; Lobser, Daniel; Maunz, Peter

We demonstrate experimental implementation of robust phase estimation (RPE) to learn the phases of X and Y rotations on a trapped Yb+ ion qubit.. Unlike many other phase estimation protocols, RPE does not require ancillae nor near-perfect state preparation and measurement operations. Additionally, its computational requirements are minimal. Via RPE, using only 352 experimental samples per phase, we estimate phases of implemented gates with errors as small as 10-4 radians, as validated using gate set tomography. We also demonstrate that these estimates exhibit Heisenberg scaling in accuracy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

SBML-PET: a Systems Biology Markup Language-based parameter estimation tool.

PubMed

Zi, Zhike; Klipp, Edda

2006-11-01

The estimation of model parameters from experimental data remains a bottleneck for a major breakthrough in systems biology. We present a Systems Biology Markup Language (SBML) based Parameter Estimation Tool (SBML-PET). The tool is designed to enable parameter estimation for biological models including signaling pathways, gene regulation networks and metabolic pathways. SBML-PET supports import and export of the models in the SBML format. It can estimate the parameters by fitting a variety of experimental data from different experimental conditions. SBML-PET has a unique feature of supporting event definition in the SMBL model. SBML models can also be simulated in SBML-PET. Stochastic Ranking Evolution Strategy (SRES) is incorporated in SBML-PET for parameter estimation jobs. A classic ODE Solver called ODEPACK is used to solve the Ordinary Differential Equation (ODE) system. http://sysbio.molgen.mpg.de/SBML-PET/. The website also contains detailed documentation for SBML-PET.

Acute and chronic environmental effects of clandestine methamphetamine waste.

PubMed

Kates, Lisa N; Knapp, Charles W; Keenan, Helen E

2014-09-15

The illicit manufacture of methamphetamine (MAP) produces substantial amounts of hazardous waste that is dumped illegally. This study presents the first environmental evaluation of waste produced from illicit MAP manufacture. Chemical oxygen demand (COD) was measured to assess immediate oxygen depletion effects. A mixture of five waste components (10mg/L/chemical) was found to have a COD (130 mg/L) higher than the European Union wastewater discharge regulations (125 mg/L). Two environmental partition coefficients, K(OW) and K(OC), were measured for several chemicals identified in MAP waste. Experimental values were input into a computer fugacity model (EPI Suite™) to estimate environmental fate. Experimental log K(OW) values ranged from -0.98 to 4.91, which were in accordance with computer estimated values. Experimental K(OC) values ranged from 11 to 72, which were much lower than the default computer values. The experimental fugacity model for discharge to water estimates that waste components will remain in the water compartment for 15 to 37 days. Using a combination of laboratory experimentation and computer modelling, the environmental fate of MAP waste products was estimated. While fugacity models using experimental and computational values were very similar, default computer models should not take the place of laboratory experimentation. Copyright © 2014 Elsevier B.V. All rights reserved.

An Investigation Into the Effects of Frequency Response Function Estimators on Model Updating

NASA Astrophysics Data System (ADS)

Ratcliffe, M. J.; Lieven, N. A. J.

1999-03-01

Model updating is a very active research field, in which significant effort has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are—unavoidably—corrupted with uncorrelated noise content. In the development and validation of model-updating strategies, a random zero-mean Gaussian variable is added to simulated test data to tax the updating routines more fully. This paper proposes a more sophisticated model for experimental measurement noise, and this is used in conjunction with several different frequency response function estimators, from the classical H1and H2to more refined estimators that purport to be unbiased. Finite-element model case studies, in conjunction with a genuine experimental test, suggest that the proposed noise model is a more realistic representation of experimental noise phenomena. The choice of estimator is shown to have a significant influence on the viability of the FRF sensitivity method. These test cases find that the use of the H2estimator for model updating purposes is contraindicated, and that there is no advantage to be gained by using the sophisticated estimators over the classical H1estimator.

Objective estimates based on experimental data and initial and final knowledge

NASA Technical Reports Server (NTRS)

Rosenbaum, B. M.

1972-01-01

An extension of the method of Jaynes, whereby least biased probability estimates are obtained, permits such estimates to be made which account for experimental data on hand as well as prior and posterior knowledge. These estimates can be made for both discrete and continuous sample spaces. The method allows a simple interpretation of Laplace's two rules: the principle of insufficient reason and the rule of succession. Several examples are analyzed by way of illustration.

Experimental Design for Parameter Estimation of Gene Regulatory Networks

PubMed Central

Timmer, Jens

2012-01-01

Systems biology aims for building quantitative models to address unresolved issues in molecular biology. In order to describe the behavior of biological cells adequately, gene regulatory networks (GRNs) are intensively investigated. As the validity of models built for GRNs depends crucially on the kinetic rates, various methods have been developed to estimate these parameters from experimental data. For this purpose, it is favorable to choose the experimental conditions yielding maximal information. However, existing experimental design principles often rely on unfulfilled mathematical assumptions or become computationally demanding with growing model complexity. To solve this problem, we combined advanced methods for parameter and uncertainty estimation with experimental design considerations. As a showcase, we optimized three simulated GRNs in one of the challenges from the Dialogue for Reverse Engineering Assessment and Methods (DREAM). This article presents our approach, which was awarded the best performing procedure at the DREAM6 Estimation of Model Parameters challenge. For fast and reliable parameter estimation, local deterministic optimization of the likelihood was applied. We analyzed identifiability and precision of the estimates by calculating the profile likelihood. Furthermore, the profiles provided a way to uncover a selection of most informative experiments, from which the optimal one was chosen using additional criteria at every step of the design process. In conclusion, we provide a strategy for optimal experimental design and show its successful application on three highly nonlinear dynamic models. Although presented in the context of the GRNs to be inferred for the DREAM6 challenge, the approach is generic and applicable to most types of quantitative models in systems biology and other disciplines. PMID:22815723

Optimal experimental designs for the estimation of thermal properties of composite materials

NASA Technical Reports Server (NTRS)

Scott, Elaine P.; Moncman, Deborah A.

1994-01-01

Reliable estimation of thermal properties is extremely important in the utilization of new advanced materials, such as composite materials. The accuracy of these estimates can be increased if the experiments are designed carefully. The objectives of this study are to design optimal experiments to be used in the prediction of these thermal properties and to then utilize these designs in the development of an estimation procedure to determine the effective thermal properties (thermal conductivity and volumetric heat capacity). The experiments were optimized by choosing experimental parameters that maximize the temperature derivatives with respect to all of the unknown thermal properties. This procedure has the effect of minimizing the confidence intervals of the resulting thermal property estimates. Both one-dimensional and two-dimensional experimental designs were optimized. A heat flux boundary condition is required in both analyses for the simultaneous estimation of the thermal properties. For the one-dimensional experiment, the parameters optimized were the heating time of the applied heat flux, the temperature sensor location, and the experimental time. In addition to these parameters, the optimal location of the heat flux was also determined for the two-dimensional experiments. Utilizing the optimal one-dimensional experiment, the effective thermal conductivity perpendicular to the fibers and the effective volumetric heat capacity were then estimated for an IM7-Bismaleimide composite material. The estimation procedure used is based on the minimization of a least squares function which incorporates both calculated and measured temperatures and allows for the parameters to be estimated simultaneously.

Investigations of the role of nonlinear couplings in structure formation and transport regulation in plasma turbulence

NASA Astrophysics Data System (ADS)

Holland, Christopher George

Studies of nonlinear couplings and dynamics in plasma turbulence are presented. Particular areas of focus are analytic studies of coherent structure formation in electron temperature gradient turbulence, measurement of nonlinear energy transfer in simulations of plasma turbulence, and bispectral analysis of experimental and computational data. The motivation for these works has been to develop and expand the existing theories of plasma transport, and verify the nonlinear predictions of those theories in simulation and experiment. In Chapter II, we study electromagnetic secondary instabilities of electron temperature gradient turbulence. The growth rate for zonal flow generation via modulational instability of electromagnetic ETG turbulence is calculated, as well as that for zonal (magnetic) field generation. In Chapter III, the stability and saturation of streamers in ETG turbulence is considered, and shown to depend sensitively upon geometry and the damping rates of the Kelvin-Helmholtz mode. Requirements for a credible theory of streamer transport are presented. In addition, a self-consistent model for interactions between ETG and ITG (ion temperature gradient) turbulence is presented. In Chapter IV, the nonlinear transfer of kinetic and internal energy is measured in simulations of plasma turbulence. The regulation of turbulence by radial decorrelation due to zonal flows and generation of zonal flows via the Reynolds stress are explicitly demonstrated, and shown to be symmetric facets of a single nonlinear process. Novel nonlinear saturation mechanisms for zonal flows are discussed. In Chapter V, measurements of fluctuation bicoherence in the edge of the DIII-D tokamak are presented. It is shown that the bicoherence increases transiently before a L-H transition, and decays to its initial value after the barrier has formed. The increase in bicoherence is localized to the region where the transport barrier forms, and shows strong coupling between well-separated frequencies. These results are qualitatively reproduced in a simple numerical "thought experiment," described in Chapter VI, which suggests that zonal flows may trigger the L-H transition.

Trade-offs in experimental designs for estimating post-release mortality in containment studies

USGS Publications Warehouse

Rogers, Mark W.; Barbour, Andrew B; Wilson, Kyle L

2014-01-01

Estimates of post-release mortality (PRM) facilitate accounting for unintended deaths from fishery activities and contribute to development of fishery regulations and harvest quotas. The most popular method for estimating PRM employs containers for comparing control and treatment fish, yet guidance for experimental design of PRM studies with containers is lacking. We used simulations to evaluate trade-offs in the number of containers (replicates) employed versus the number of fish-per container when estimating tagging mortality. We also investigated effects of control fish survival and how among container variation in survival affects the ability to detect additive mortality. Simulations revealed that high experimental effort was required when: (1) additive treatment mortality was small, (2) control fish mortality was non-negligible, and (3) among container variability in control fish mortality exceeded 10% of the mean. We provided programming code to allow investigators to compare alternative designs for their individual scenarios and expose trade-offs among experimental design options. Results from our simulations and simulation code will help investigators develop efficient PRM experimental designs for precise mortality assessment.

Survey of engineering computational methods and experimental programs for estimating supersonic missile aerodynamic characteristics

NASA Technical Reports Server (NTRS)

Sawyer, W. C.; Allen, J. M.; Hernandez, G.; Dillenius, M. F. E.; Hemsch, M. J.

1982-01-01

This paper presents a survey of engineering computational methods and experimental programs used for estimating the aerodynamic characteristics of missile configurations. Emphasis is placed on those methods which are suitable for preliminary design of conventional and advanced concepts. An analysis of the technical approaches of the various methods is made in order to assess their suitability to estimate longitudinal and/or lateral-directional characteristics for different classes of missile configurations. Some comparisons between the predicted characteristics and experimental data are presented. These comparisons are made for a large variation in flow conditions and model attitude parameters. The paper also presents known experimental research programs developed for the specific purpose of validating analytical methods and extending the capability of data-base programs.

Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

NASA Astrophysics Data System (ADS)

Ehrlich, André; Bierwirth, Eike; Istomina, Larysa; Wendisch, Manfred

2017-09-01

The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff, C, and reff, S show a continuous transition of cloud properties across snow-covered sea ice and open water and are consistent with estimates based on satellite data. It is shown that the uncertainties of the trispectral retrieval increase for high values of τ, and low reff, S but nevertheless allow the effective snow grain size in cloud-covered areas to be estimated.

Estimation of interfacial area in a packed cross-flow cascade with distillation of ethanol-water, methanol-water, and hexane-heptane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velaga, A.

1986-01-01

Packed cross-flow internals consisting of four and ten stages including the samplers for liquid and vapor were fabricated to fit into the existing distillation column. Experiments were conducted using methanol-water, ethanol-water and hexane-heptane binary mixtures. The experimental data were collected for compositions of inlet and exist streams of cross-flow stages. The overall gas phase height transfer units (H/sub og/) were estimated using the experimental data. H/sub og/ values were compared to those of counter current conditions. The individual mass transfer coefficients in the liquid and vapor phases were estimated using the collected experimental data for degree of separation, flow ratesmore » and physical properties of the binary system used. The physical properties were estimated at an average temperature of the specific cross-flow stage. The mass transfer coefficients were evaluated using three different correlations proposed by Shulman. Onda and Hayashi respectively. The interfacial areas were estimated using the evaluated mass transfer coefficients and the experimental data at each stage of the column for different runs and compared.« less

Accurate position estimation methods based on electrical impedance tomography measurements

NASA Astrophysics Data System (ADS)

Vergara, Samuel; Sbarbaro, Daniel; Johansen, T. A.

2017-08-01

Electrical impedance tomography (EIT) is a technology that estimates the electrical properties of a body or a cross section. Its main advantages are its non-invasiveness, low cost and operation free of radiation. The estimation of the conductivity field leads to low resolution images compared with other technologies, and high computational cost. However, in many applications the target information lies in a low intrinsic dimensionality of the conductivity field. The estimation of this low-dimensional information is addressed in this work. It proposes optimization-based and data-driven approaches for estimating this low-dimensional information. The accuracy of the results obtained with these approaches depends on modelling and experimental conditions. Optimization approaches are sensitive to model discretization, type of cost function and searching algorithms. Data-driven methods are sensitive to the assumed model structure and the data set used for parameter estimation. The system configuration and experimental conditions, such as number of electrodes and signal-to-noise ratio (SNR), also have an impact on the results. In order to illustrate the effects of all these factors, the position estimation of a circular anomaly is addressed. Optimization methods based on weighted error cost functions and derivate-free optimization algorithms provided the best results. Data-driven approaches based on linear models provided, in this case, good estimates, but the use of nonlinear models enhanced the estimation accuracy. The results obtained by optimization-based algorithms were less sensitive to experimental conditions, such as number of electrodes and SNR, than data-driven approaches. Position estimation mean squared errors for simulation and experimental conditions were more than twice for the optimization-based approaches compared with the data-driven ones. The experimental position estimation mean squared error of the data-driven models using a 16-electrode setup was less than 0.05% of the tomograph radius value. These results demonstrate that the proposed approaches can estimate an object’s position accurately based on EIT measurements if enough process information is available for training or modelling. Since they do not require complex calculations it is possible to use them in real-time applications without requiring high-performance computers.

Use of Internal Consistency Coefficients for Estimating Reliability of Experimental Tasks Scores

PubMed Central

Green, Samuel B.; Yang, Yanyun; Alt, Mary; Brinkley, Shara; Gray, Shelley; Hogan, Tiffany; Cowan, Nelson

2017-01-01

Reliabilities of scores for experimental tasks are likely to differ from one study to another to the extent that the task stimuli change, the number of trials varies, the type of individuals taking the task changes, the administration conditions are altered, or the focal task variable differs. Given reliabilities vary as a function of the design of these tasks and the characteristics of the individuals taking them, making inferences about the reliability of scores in an ongoing study based on reliability estimates from prior studies is precarious. Thus, it would be advantageous to estimate reliability based on data from the ongoing study. We argue that internal consistency estimates of reliability are underutilized for experimental task data and in many applications could provide this information using a single administration of a task. We discuss different methods for computing internal consistency estimates with a generalized coefficient alpha and the conditions under which these estimates are accurate. We illustrate use of these coefficients using data for three different tasks. PMID:26546100

Classes of Split-Plot Response Surface Designs for Equivalent Estimation

NASA Technical Reports Server (NTRS)

Parker, Peter A.; Kowalski, Scott M.; Vining, G. Geoffrey

2006-01-01

When planning an experimental investigation, we are frequently faced with factors that are difficult or time consuming to manipulate, thereby making complete randomization impractical. A split-plot structure differentiates between the experimental units associated with these hard-to-change factors and others that are relatively easy-to-change and provides an efficient strategy that integrates the restrictions imposed by the experimental apparatus. Several industrial and scientific examples are presented to illustrate design considerations encountered in the restricted randomization context. In this paper, we propose classes of split-plot response designs that provide an intuitive and natural extension from the completely randomized context. For these designs, the ordinary least squares estimates of the model are equivalent to the generalized least squares estimates. This property provides best linear unbiased estimators and simplifies model estimation. The design conditions that allow for equivalent estimation are presented enabling design construction strategies to transform completely randomized Box-Behnken, equiradial, and small composite designs into a split-plot structure.

Effects of Dexmedetomidine on motor- and somatosensory-evoked potentials in patients with thoracic spinal cord tumor: a randomized controlled trial.

PubMed

Li, Yan; Meng, Lingzhong; Peng, Yuming; Qiao, Hui; Guo, Lanjun; Han, Ruquan; Gelb, Adrian W

2016-08-02

We hypothesized that the addition of dexmedetomidine in a clinically relevant dose to propofol-remifentanil anesthesia regimen does not exert an adverse effect on motor-evoked potentials (MEP) and somatosensory-evoked potentials (SSEP) in adult patients undergoing thoracic spinal cord tumor resection. Seventy-one adult patients were randomized into three groups. Propofol group (n = 25): propofol-remifentanil regimenand the dosage was adjusted to maintain the bispectral index (BIS) between 40 and 50. DP adjusted group (n = 23): Dexmedetomidine (0.5 μg/kg loading dose infused over 10 min followed by a constant infusion of 0.5 μg/kg/h) was added to the propofol-remifentanil regimen and propofol was adjusted to maintain BIS between 40 and 50. DP unadjusted group (n = 23): Dexmedetomidine (administer as DP adjusted group) was added to the propofol-remifentanil regimen and propofol was not adjusted. All patients received MEP, SSEP and BIS monitoring. There were no significant changes in the amplitude and latency of MEP and SSEP among different groups (P > 0.05). The estimated propofol plasma concentration in DP adjusted group (2.7 ± 0.3 μg/ml) was significantly lower than in propofol group (3.1 ± 0.2 μg/ml) and DP unadjusted group (3.1 ± 0.2 μg/ml) (P = 0.000). BIS in DP unadjusted group (35 ± 5) was significantly lower than in propofol group (44 ± 3) (P = 0.000). The addition of dexmedetomidine to propofol-remifentanil regimen does not exert an adverse effect on MEP and SSEP monitoring in adult patients undergoing thoracic spinal cord tumor resection. The study was registered with the Chinese Clinical Trial Registry on January 31st, 2014. The reference number was ChiCTR-TRC-14004229.

Assessing the depth of isoflurane anaesthesia during cardiopulmonary bypass.

PubMed

Ng, Ka Ting; Alston, R Peter; Just, George; McKenzie, Chris

2018-03-01

Bispectral index (BIS) and monitoring of end-tidal concentration may be associated with a reduction in the incidence of awareness during volatile-based general anaesthesia. An analogue of end-tidal concentration during cardiopulmonary bypass (CPB) is measuring exhausted isoflurane concentration from the oxygenator as an estimate to blood and, so, brain concentration. The aim of this study was to determine the relationships between oxygenator exhaust and blood concentrations of isoflurane and the BIS score during CPB when administering isoflurane into the sweep gas supply to the oxygenator. Seventeen patients undergoing elective cardiac surgery using CPB and isoflurane with BIS monitoring were recruited in a single-centre university hospital. Isoflurane gas was delivered via a calibrated vaporiser at the beginning of anaesthetic induction. Radial arterial blood samples were collected after the initiation of CPB and before aortic cross-clamping, which were analysed for isoflurane by gas chromatography and mass spectrometry. The BIS score and the concentration of exhausted isoflurane from the oxygenator membrane, as measured by an anaesthetic gas analyser, were recorded at the time of blood sampling. The mean duration of anaesthetic induction to arterial blood sampling was 90 min (95%CI: 80,100). On CPB, the median BIS was 39 (range, 7-43) and the mean oxygenator exhaust isoflurane concentration was 1.24 ± 0.21%. No significant correlation was demonstrated between BIS with arterial isoflurane concentration (r=-0.19, p=0.47) or oxygenator exhaust isoflurane concentration (r=0.07, p=0.80). Mixed-venous blood temperature was moderately correlated to BIS (r=0.50, p=0.04). Oxygenator exhaust isoflurane concentration was moderately, positively correlated with its arterial concentration (r=0.64, p<0.01). In conclusion, in patients undergoing heart surgery with CPB, the findings of this study indicate that, whilst oxygenator exhaust concentrations were significantly associated with arterial concentrations of isoflurane, neither had any association with the BIS scores, whereas body temperature has moderate positive correlation.

A Pharmacokinetics-Neural Mass Model (PK-NMM) for the Simulation of EEG Activity during Propofol Anesthesia

PubMed Central

Liang, Zhenhu; Duan, Xuejing; Su, Cui; Voss, Logan; Sleigh, Jamie; Li, Xiaoli

2015-01-01

Modeling the effects of anesthetic drugs on brain activity is very helpful in understanding anesthesia mechanisms. The aim of this study was to set up a combined model to relate actual drug levels to EEG dynamics and behavioral states during propofol-induced anesthesia. We proposed a new combined theoretical model based on a pharmacokinetics (PK) model and a neural mass model (NMM), which we termed PK-NMM—with the aim of simulating electroencephalogram (EEG) activity during propofol-induced general anesthesia. The PK model was used to derive propofol effect-site drug concentrations (C eff) based on the actual drug infusion regimen. The NMM model took C eff as the control parameter to produce simulated EEG-like (sEEG) data. For comparison, we used real prefrontal EEG (rEEG) data of nine volunteers undergoing propofol anesthesia from a previous experiment. To see how well the sEEG could describe the dynamic changes of neural activity during anesthesia, the rEEG data and the sEEG data were compared with respect to: power-frequency plots; nonlinear exponent (permutation entropy (PE)); and bispectral SynchFastSlow (SFS) parameters. We found that the PK-NMM model was able to reproduce anesthesia EEG-like signals based on the estimated drug concentration and patients’ condition. The frequency spectrum indicated that the frequency power peak of the sEEG moved towards the low frequency band as anesthesia deepened. Different anesthetic states could be differentiated by the PE index. The correlation coefficient of PE was 0.80±0.13 (mean±standard deviation) between rEEG and sEEG for all subjects. Additionally, SFS could track the depth of anesthesia and the SFS of rEEG and sEEG were highly correlated with a correlation coefficient of 0.77±0.13. The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity. PMID:26720495

Theoretical and experimental investigations of sensor location for optimal aeroelastic system state estimation

NASA Technical Reports Server (NTRS)

Liu, G.

1985-01-01

One of the major concerns in the design of an active control system is obtaining the information needed for effective feedback. This involves the combination of sensing and estimation. A sensor location index is defined as the weighted sum of the mean square estimation errors in which the sensor locations can be regarded as estimator design parameters. The design goal is to choose these locations to minimize the sensor location index. The choice of the number of sensors is a tradeoff between the estimation quality based upon the same performance index and the total costs of installing and maintaining extra sensors. An experimental study for choosing the sensor location was conducted on an aeroelastic system. The system modeling which includes the unsteady aerodynamics model developed by Stephen Rock was improved. Experimental results verify the trend of the theoretical predictions of the sensor location index for different sensor locations at various wind speeds.

Optimal experimental design for improving the estimation of growth parameters of Lactobacillus viridescens from data under non-isothermal conditions.

PubMed

Longhi, Daniel Angelo; Martins, Wiaslan Figueiredo; da Silva, Nathália Buss; Carciofi, Bruno Augusto Mattar; de Aragão, Gláucia Maria Falcão; Laurindo, João Borges

2017-01-02

In predictive microbiology, the model parameters have been estimated using the sequential two-step modeling (TSM) approach, in which primary models are fitted to the microbial growth data, and then secondary models are fitted to the primary model parameters to represent their dependence with the environmental variables (e.g., temperature). The Optimal Experimental Design (OED) approach allows reducing the experimental workload and costs, and the improvement of model identifiability because primary and secondary models are fitted simultaneously from non-isothermal data. Lactobacillus viridescens was selected to this study because it is a lactic acid bacterium of great interest to meat products preservation. The objectives of this study were to estimate the growth parameters of L. viridescens in culture medium from TSM and OED approaches and to evaluate both the number of experimental data and the time needed in each approach and the confidence intervals of the model parameters. Experimental data for estimating the model parameters with TSM approach were obtained at six temperatures (total experimental time of 3540h and 196 experimental data of microbial growth). Data for OED approach were obtained from four optimal non-isothermal profiles (total experimental time of 588h and 60 experimental data of microbial growth), two profiles with increasing temperatures (IT) and two with decreasing temperatures (DT). The Baranyi and Roberts primary model and the square root secondary model were used to describe the microbial growth, in which the parameters b and T min (±95% confidence interval) were estimated from the experimental data. The parameters obtained from TSM approach were b=0.0290 (±0.0020) [1/(h 0.5 °C)] and T min =-1.33 (±1.26) [°C], with R 2 =0.986 and RMSE=0.581, and the parameters obtained with the OED approach were b=0.0316 (±0.0013) [1/(h 0.5 °C)] and T min =-0.24 (±0.55) [°C], with R 2 =0.990 and RMSE=0.436. The parameters obtained from OED approach presented smaller confidence intervals and best statistical indexes than those from TSM approach. Besides, less experimental data and time were needed to estimate the model parameters with OED than TSM. Furthermore, the OED model parameters were validated with non-isothermal experimental data with great accuracy. In this way, OED approach is feasible and is a very useful tool to improve the prediction of microbial growth under non-isothermal condition. Copyright © 2016 Elsevier B.V. All rights reserved.

An improved swarm optimization for parameter estimation and biological model selection.

PubMed

Abdullah, Afnizanfaizal; Deris, Safaai; Mohamad, Mohd Saberi; Anwar, Sohail

2013-01-01

One of the key aspects of computational systems biology is the investigation on the dynamic biological processes within cells. Computational models are often required to elucidate the mechanisms and principles driving the processes because of the nonlinearity and complexity. The models usually incorporate a set of parameters that signify the physical properties of the actual biological systems. In most cases, these parameters are estimated by fitting the model outputs with the corresponding experimental data. However, this is a challenging task because the available experimental data are frequently noisy and incomplete. In this paper, a new hybrid optimization method is proposed to estimate these parameters from the noisy and incomplete experimental data. The proposed method, called Swarm-based Chemical Reaction Optimization, integrates the evolutionary searching strategy employed by the Chemical Reaction Optimization, into the neighbouring searching strategy of the Firefly Algorithm method. The effectiveness of the method was evaluated using a simulated nonlinear model and two biological models: synthetic transcriptional oscillators, and extracellular protease production models. The results showed that the accuracy and computational speed of the proposed method were better than the existing Differential Evolution, Firefly Algorithm and Chemical Reaction Optimization methods. The reliability of the estimated parameters was statistically validated, which suggests that the model outputs produced by these parameters were valid even when noisy and incomplete experimental data were used. Additionally, Akaike Information Criterion was employed to evaluate the model selection, which highlighted the capability of the proposed method in choosing a plausible model based on the experimental data. In conclusion, this paper presents the effectiveness of the proposed method for parameter estimation and model selection problems using noisy and incomplete experimental data. This study is hoped to provide a new insight in developing more accurate and reliable biological models based on limited and low quality experimental data.

Graphical Models for Quasi-Experimental Designs

ERIC Educational Resources Information Center

Kim, Yongnam; Steiner, Peter M.; Hall, Courtney E.; Su, Dan

2016-01-01

Experimental and quasi-experimental designs play a central role in estimating cause-effect relationships in education, psychology, and many other fields of the social and behavioral sciences. This paper presents and discusses the causal graphs of experimental and quasi-experimental designs. For quasi-experimental designs the authors demonstrate…

An estimating formula for ion-atom association rates in gases

NASA Technical Reports Server (NTRS)

Chatterjee, B. K.; Johnsen, R.

1990-01-01

A simple estimating formula is derived for rate coefficients of three-body ion atom association in gases and compare its predictions to experimental data on ion association and three-body radiative charge transfer reactions of singly- and doubly-charged rare-gas ions. The formula appears to reproduce most experimental data quite well. It may be useful for estimating the rates of reactions that have not been studied in the laboratory.

Neutron optics concept for the materials engineering diffractometer at the ESS

NASA Astrophysics Data System (ADS)

Šaroun, J.; Fenske, J.; Rouijaa, M.; Beran, P.; Navrátil, J.; Lukáš, P.; Schreyer, A.; Strobl, M.

2016-09-01

The Beamline for European Materials Engineering Research (BEER) has been recently proposed to be built at the European Spallation Source (ESS). The presented concept of neutron delivery optics for this instrument addresses the problems of bi-spectral beam extraction from a small moderator, optimization of neutron guides profile for long-range neutron transport and focusing at the sample under various constraints. They include free space before and after the guides, a narrow guide section with gaps for choppers, closing of direct line of sight and cost reduction by optimization of the guides cross-section and coating. A system of slits and exchangeable focusing optics is proposed in order to match various wavelength resolution options provided by the pulse shaping and modulation choppers, which permits to efficiently trade resolution for intensity in a wide range. Simulated performance characteristics such as brilliance transfer ratio are complemented by the analysis of the histories of “useful” neutrons obtained by back tracing neutrons hitting the sample, which helps to optimize some of the neutron guide parameters such as supermirror coating.

Glimpses of Kolmogorov's spectral energy dynamics in nonlinear acoustic waves

NASA Astrophysics Data System (ADS)

Gupta, Prateek; Scalo, Carlo

2017-11-01

Gupta, Lodato, and Scalo (AIAA 2017) have demonstrated the existence of an equilibrium spectral energy cascade in shock waves formed as a result of continued modal thermoacoustic amplification consistent with Kolmogorov's theory for high-Reynolds-number hydrodynamic turbulence. In this talk we discuss the derivation of a perturbation energy density norm that guarantees energy conservation during the nonlinear wave steepening process, analogous to inertial subrange turbulent energy cascade dynamics. The energy cascade is investigated via a bi-spectral analysis limited to wave-numbers and frequencies lower than the ones associated with the shock, analogous to the viscous dissipation length scale in turbulence. The proposed norm is derived by recombining second-order nonlinear acoustic equations and is positive definite; moreover, it decays to zero in the presence of viscous dissipation and is hence classifiable as a Lyapunov function of acoustic perturbation variables. The cumulative energy spectrum wavenumber distribution demonstrates a -3/2 decay law in the inertial range. The governing equation for the thus-derived energy norm highlights terms responsible for energy cascade towards higher harmonics, analogous to vortex stretching terms in hydrodynamic turbulence.

The role of magnesium as an adjuvant during general anaesthesia.

PubMed

Gupta, K; Vohra, V; Sood, J

2006-11-01

Magnesium sulphate is used extensively in the treatment of eclampsia, and is also used to treat refractory arrhythmias, asthma, myocardial ischaemia and acute respiratory failure. We studied the interaction between magnesium sulphate and the anaesthetic agents propofol, rocuronium bromide and fentanyl citrate. This randomised, double blind study was conducted in 50 patients. The magnesium group A (n = 25) received 30 mg x kg(-1) magnesium sulphate before induction of anaesthesia and 10 mg x kg(-1) continuously intra-operatively until the end of surgery. Group B (n = 25) received the same volume of isotonic saline. Propofol, rocuronium and fentanyl infusions were started and the patients lungs' were ventilated with 33% oxygen in nitrous oxide. Anaesthetic depth was maintained at a bispectral index value of between 40 and 60. Muscle relaxation was maintained at a train-of-four count of 1 throughout surgery using neuromuscular monitoring. The fentanyl infusion was titrated to haemodynamic variables: heart rate and blood pressure. We concluded that magnesium sulphate has anaesthetic, analgesic and muscle relaxation effects and significantly reduces the drug requirements of propofol, rocuronium and fentanyl during anaesthesia.

A technical description of a novel pharmacological anesthesia robot.

PubMed

Wehbe, Mohamad; Arbeid, Erik; Cyr, Shantale; Mathieu, Pierre A; Taddei, Riccardo; Morse, Joshua; Hemmerling, Thomas M

2014-02-01

To control the three components of general anesthesia (hypnosis, analgesia, and neuromuscular blockade), an automated closed-loop, anesthesia-drug delivery system (McSleepy) was developed. Bispectral index was used as the control variable for hypnosis, the analgoscore for analgesia, and phonomyography for neuromuscular blockade. McSleepy can be used to control the induction, maintenance and emergence from general anesthesia. To do so, a large touch screen is used to provide a user friendly interface, permitting bidirectional communication: the user giving information about the different stages of anesthesia, and the system prompting the anesthesiologist to perform certain actions such as mask ventilation, intubation or waking-up the patient using audio clips with voice commands. Several safety features were implemented to provide a secure and reliable anesthesia. Preliminary results of 15 patients are presented in this paper. Evaluation of McSleepy was done through an assessment of its clinical performance and using Varvel's performance indices. The system was found to be clinically useful by providing good precision in drug administration and reliable results for the duration of a general anesthesia.

Cloud cover analysis associated to cut-off low-pressure systems over Europe using Meteosat Imagery

NASA Astrophysics Data System (ADS)

Delgado, G.; Redaño, A.; Lorente, J.; Nieto, R.; Gimeno, L.; Ribera, P.; Barriopedro, D.; García-Herrera, R.; Serrano, A.

2007-04-01

This paper reports a cloud cover analysis of cut-off low pressure systems (COL) using a pattern recognition method applied to IR and VIS bispectral histograms. 35 COL occurrences were studied over five years (1994-1998). Five cloud types were identified in COLs, of which high clouds (HCC) and deep convective clouds (DCC) were found to be the most relevant to characterize COL systems, though not the most numerous. Cloud cover in a COL is highly dependent on its stage of development, but a higher percentage of cloud cover is always present in the frontal zone, attributable due to higher amounts of high and deep convective clouds. These general characteristics are most marked during the first stage (when the amplitude of the geopotencial wave increases) and second stage (characterized by the development of a cold upper level low), closed cyclonic circulation minimizing differences between rearward and frontal zones during the third stage. The probability of heavy rains during this stage decreases considerably. The centres of mass of high and deep convective clouds move towards the COL-axis centre during COL evolution.

Investigation of the effects of the macrophysical and microphysical properties of cirrus clouds on the retrieval of optical properties: Results for FIRE 2

NASA Technical Reports Server (NTRS)

Stackhouse, Paul W., Jr.; Stephens, Graeme L.

1993-01-01

Due to the prevalence and persistence of cirrus cloudiness across the globe, cirrus clouds are believed to have an important effect on the climate. Stephens et al., (1990) among others have shown that the important factor determining how cirrus clouds modulate the climate is the balance between the albedo and emittance effect of the cloud systems. This factor was shown to depend in part upon the effective sizes of the cirrus cloud particles. Since effective sizes of cirrus cloud microphysical distributions are used as a basis of parameterizations in climate models, it is crucial that the relationships between effective sizes and radiative properties be clearly established. In this preliminary study, the retrieval of cirrus cloud effective sizes are examined using a two dimensional radiative transfer model for a cirrus cloud case sampled during FIRE Cirrus 11. The purpose of this paper is to present preliminary results from the SHSG model demonstrating the sensitivity of the bispectral relationships of reflected radiances and thus the retrieval of effective sizes to phase function and dimensionality.

Propofol dose and incidence of dreaming during sedation.

PubMed

Eer, Audrey Singyi; Padmanabhan, Usha; Leslie, Kate

2009-10-01

Dreaming is commonly reported after propofol-based sedation. We measured the incidence of dreaming and bispectral index (BIS) values in colonoscopy patients sedated with combinations of propofol, midazolam and fentanyl. Two hundred patients presenting for elective outpatient colonoscopy were sedated with combinations of propofol, midazolam and fentanyl. BIS was monitored throughout the procedure. Patients were interviewed immediately after they emerged from sedation. The primary end point was a report of dreaming during sedation. Ninety-seven patients were administered propofol alone, 44 were administered propofol and fentanyl, 16 were administered propofol and midazolam and 43 were administered propofol, midazolam and fentanyl. Dreaming was reported by 19% of patients. Dreamers received higher doses of propofol and had lower BIS values during sedation. Age of 50 years or less, preoperative quality of recovery score of less than 14, higher home dream recall, propofol dose of more than 300 mg and time to Observers' Assessment of Alertness/Sedation score equalling 5 of 8 min or less were independent predictors of dreaming. Dreaming during sedation is associated with higher propofol dose and lower BIS values.

Assessing Methods for Generalizing Experimental Impact Estimates to Target Populations

ERIC Educational Resources Information Center

Kern, Holger L.; Stuart, Elizabeth A.; Hill, Jennifer; Green, Donald P.

2016-01-01

Randomized experiments are considered the gold standard for causal inference because they can provide unbiased estimates of treatment effects for the experimental participants. However, researchers and policymakers are often interested in using a specific experiment to inform decisions about other target populations. In education research,…

Model-Based Estimation of Ankle Joint Stiffness

PubMed Central

Misgeld, Berno J. E.; Zhang, Tony; Lüken, Markus J.; Leonhardt, Steffen

2017-01-01

We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The model incorporates a two-dimensional kinematic description in the sagittal plane for the calculation of muscle lever arms and torques. To reduce estimation errors due to model uncertainties, a filtering algorithm is necessary that employs segmental orientation sensor measurements. Because of the model’s inherent nonlinearities and nonsmooth dynamics, a square-root cubature Kalman filter was developed. The performance of the novel estimation approach was evaluated in silico and in an experimental procedure. The experimental study was conducted with body-worn sensors and a test-bench that was specifically designed to obtain reference angle and torque measurements for a single joint. Results show that the filter is able to reconstruct joint angle positions, velocities and torque, as well as, joint stiffness during experimental test bench movements. PMID:28353683

75 FR 2197 - Western Pacific Fisheries; Regulatory Restructuring

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-14

....16 Vessel identification. Sec. 665.17 Experimental fishing..... Sec. 665.17 Experimental fishing. Sec.... 0586, and -0589. Sec. 665.17 Experimental Sec. 665.17 0648-0214 and -0490. fishing. Experimental...) experimental fishing reports estimated at 4 hours (hr) per reporting action; (d) sales and transshipment...

A practical model for pressure probe system response estimation (with review of existing models)

NASA Astrophysics Data System (ADS)

Hall, B. F.; Povey, T.

2018-04-01

The accurate estimation of the unsteady response (bandwidth) of pneumatic pressure probe systems (probe, line and transducer volume) is a common practical problem encountered in the design of aerodynamic experiments. Understanding the bandwidth of the probe system is necessary to capture unsteady flow features accurately. Where traversing probes are used, the desired traverse speed and spatial gradients in the flow dictate the minimum probe system bandwidth required to resolve the flow. Existing approaches for bandwidth estimation are either complex or inaccurate in implementation, so probes are often designed based on experience. Where probe system bandwidth is characterized, it is often done experimentally, requiring careful experimental set-up and analysis. There is a need for a relatively simple but accurate model for estimation of probe system bandwidth. A new model is presented for the accurate estimation of pressure probe bandwidth for simple probes commonly used in wind tunnel environments; experimental validation is provided. An additional, simple graphical method for air is included for convenience.

Real-Time Parameter Estimation Method Applied to a MIMO Process and its Comparison with an Offline Identification Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplanoglu, Erkan; Safak, Koray K.; Varol, H. Selcuk

2009-01-12

An experiment based method is proposed for parameter estimation of a class of linear multivariable systems. The method was applied to a pressure-level control process. Experimental time domain input/output data was utilized in a gray-box modeling approach. Prior knowledge of the form of the system transfer function matrix elements is assumed to be known. Continuous-time system transfer function matrix parameters were estimated in real-time by the least-squares method. Simulation results of experimentally determined system transfer function matrix compare very well with the experimental results. For comparison and as an alternative to the proposed real-time estimation method, we also implemented anmore » offline identification method using artificial neural networks and obtained fairly good results. The proposed methods can be implemented conveniently on a desktop PC equipped with a data acquisition board for parameter estimation of moderately complex linear multivariable systems.« less

Quantum state estimation when qubits are lost: a no-data-left-behind approach

DOE PAGES

Williams, Brian P.; Lougovski, Pavel

2017-04-06

We present an approach to Bayesian mean estimation of quantum states using hyperspherical parametrization and an experiment-specific likelihood which allows utilization of all available data, even when qubits are lost. With this method, we report the first closed-form Bayesian mean and maximum likelihood estimates for the ideal single qubit. Due to computational constraints, we utilize numerical sampling to determine the Bayesian mean estimate for a photonic two-qubit experiment in which our novel analysis reduces burdens associated with experimental asymmetries and inefficiencies. This method can be applied to quantum states of any dimension and experimental complexity.

Replicating Experimental Impact Estimates Using a Regression Discontinuity Approach. NCEE 2012-4025

ERIC Educational Resources Information Center

Gleason, Philip M.; Resch, Alexandra M.; Berk, Jillian A.

2012-01-01

This NCEE Technical Methods Paper compares the estimated impacts of an educational intervention using experimental and regression discontinuity (RD) study designs. The analysis used data from two large-scale randomized controlled trials--the Education Technology Evaluation and the Teach for America Study--to provide evidence on the performance of…

Canopy Level Emissions of 2-methyl-3-buten-2-ol, monoterpenes, and sesquiterpenes from a Pinus taeda Experimental Plantation

EPA Science Inventory

Emissions of biogenic volatile organic compounds (BVOC) observed during 2007 from a Pinus taeda experimental plantation in Central North Carolina are compared with model estimates from MEGAN 2.1. Relaxed Eddy Accumulation (REA) estimates of 2-methyl-3-buten-2-ol (MBO) fluxes are ...

It Pays to Compare: An Experimental Study on Computational Estimation

ERIC Educational Resources Information Center

Star, Jon R.; Rittle-Johnson, Bethany

2009-01-01

Comparing and contrasting examples is a core cognitive process that supports learning in children and adults across a variety of topics. In this experimental study, we evaluated the benefits of supporting comparison in a classroom context for children learning about computational estimation. Fifth- and sixth-grade students (N = 157) learned about…

A fast and accurate frequency estimation algorithm for sinusoidal signal with harmonic components

NASA Astrophysics Data System (ADS)

Hu, Jinghua; Pan, Mengchun; Zeng, Zhidun; Hu, Jiafei; Chen, Dixiang; Tian, Wugang; Zhao, Jianqiang; Du, Qingfa

2016-10-01

Frequency estimation is a fundamental problem in many applications, such as traditional vibration measurement, power system supervision, and microelectromechanical system sensors control. In this paper, a fast and accurate frequency estimation algorithm is proposed to deal with low efficiency problem in traditional methods. The proposed algorithm consists of coarse and fine frequency estimation steps, and we demonstrate that it is more efficient than conventional searching methods to achieve coarse frequency estimation (location peak of FFT amplitude) by applying modified zero-crossing technique. Thus, the proposed estimation algorithm requires less hardware and software sources and can achieve even higher efficiency when the experimental data increase. Experimental results with modulated magnetic signal show that the root mean square error of frequency estimation is below 0.032 Hz with the proposed algorithm, which has lower computational complexity and better global performance than conventional frequency estimation methods.

Experimental Estimation of Entanglement at the Quantum Limit

NASA Astrophysics Data System (ADS)

Brida, Giorgio; Degiovanni, Ivo Pietro; Florio, Angela; Genovese, Marco; Giorda, Paolo; Meda, Alice; Paris, Matteo G. A.; Shurupov, Alexander

2010-03-01

Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise, experimental feasible measure of entanglement. Nevertheless, such measurements are limited both from experimental uncertainties and intrinsic quantum bounds. Here we present an experiment where the amount of entanglement of a family of two-qubit mixed photon states is estimated with the ultimate precision allowed by quantum mechanics.

The price elasticity of demand for heroin: matched longitudinal and experimental evidence#

PubMed Central

Olmstead, Todd A.; Alessi, Sheila M.; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M.

2015-01-01

This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally-induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately −0.80. PMID:25702687

Estimation of dose rates at the entrance surface for exposure scenarios of total body irradiation using MCNPX code

NASA Astrophysics Data System (ADS)

Cunha, J. S.; Cavalcante, F. R.; Souza, S. O.; Souza, D. N.; Santos, W. S.; Carvalho Júnior, A. B.

2017-11-01

One of the main criteria that must be held in Total Body Irradiation (TBI) is the uniformity of dose in the body. In TBI procedures the certification that the prescribed doses are absorbed in organs is made with dosimeters positioned on the patient skin. In this work, we modelled TBI scenarios in the MCNPX code to estimate the entrance dose rate in the skin for comparison and validation of simulations with experimental measurements from literature. Dose rates were estimated simulating an ionization chamber laterally positioned on thorax, abdomen, leg and thigh. Four exposure scenarios were simulated: ionization chamber (S1), TBI room (S2), and patient represented by hybrid phantom (S3) and water stylized phantom (S4) in sitting posture. The posture of the patient in experimental work was better represented by S4 compared with hybrid phantom, and this led to minimum and maximum percentage differences of 1.31% and 6.25% to experimental measurements for thorax and thigh regions, respectively. As for all simulations reported here the percentage differences in the estimated dose rates were less than 10%, we considered that the obtained results are consistent with experimental measurements and the modelled scenarios are suitable to estimate the absorbed dose in organs during TBI procedure.

Novel methods to estimate the enantiomeric ratio and the kinetic parameters of enantiospecific enzymatic reactions.

PubMed

Machado, G D.C.; Paiva, L M.C.; Pinto, G F.; Oestreicher, E G.

2001-03-08

1The Enantiomeric Ratio (E) of the enzyme, acting as specific catalysts in resolution of enantiomers, is an important parameter in the quantitative description of these chiral resolution processes. In the present work, two novel methods hereby called Method I and II, for estimating E and the kinetic parameters Km and Vm of enantiomers were developed. These methods are based upon initial rate (v) measurements using different concentrations of enantiomeric mixtures (C) with several molar fractions of the substrate (x). Both methods were tested using simulated "experimental data" and actual experimental data. Method I is easier to use than Method II but requires that one of the enantiomers is available in pure form. Method II, besides not requiring the enantiomers in pure form shown better results, as indicated by the magnitude of the standard errors of estimates. The theoretical predictions were experimentally confirmed by using the oxidation of 2-butanol and 2-pentanol catalyzed by Thermoanaerobium brockii alcohol dehydrogenase as reaction models. The parameters E, Km and Vm were estimated by Methods I and II with precision and were not significantly different from those obtained experimentally by direct estimation of E from the kinetic parameters of each enantiomer available in pure form.

Dynamic modulus estimation and structural vibration analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.

1998-11-18

Often the dynamic elastic modulus of a material with frequency dependent properties is difficult to estimate. These uncertainties are compounded in any structural vibration analysis using the material properties. Here, different experimental techniques are used to estimate the properties of a particular elastomeric material over a broad frequency range. Once the properties are determined, various structures incorporating the elastomer are analyzed by an interactive finite element method to determine natural frequencies and mode shapes. Then, the finite element results are correlated with results obtained by experimental modal analysis.

DETECTORS AND EXPERIMENTAL METHODS: Heuristic approach for peak regions estimation in gamma-ray spectra measured by a NaI detector

NASA Astrophysics Data System (ADS)

Zhu, Meng-Hua; Liu, Liang-Gang; You, Zhong; Xu, Ao-Ao

2009-03-01

In this paper, a heuristic approach based on Slavic's peak searching method has been employed to estimate the width of peak regions for background removing. Synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectrum, we find it is simple and effective enough to be used together with the Statistics-sensitive Nonlinear Iterative Peak-Clipping method.

Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue

NASA Astrophysics Data System (ADS)

González, C. A.; Lozano, L. M.; Uscanga, M. C.; Silva, J. G.; Polo, S. M.

2013-04-01

Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.

Estimations of global warming potentials from computational chemistry calculations for CH(2)F(2) and other fluorinated methyl species verified by comparison to experiment.

PubMed

Blowers, Paul; Hollingshead, Kyle

2009-05-21

In this work, the global warming potential (GWP) of methylene fluoride (CH(2)F(2)), or HFC-32, is estimated through computational chemistry methods. We find our computational chemistry approach reproduces well all phenomena important for predicting global warming potentials. Geometries predicted using the B3LYP/6-311g** method were in good agreement with experiment, although some other computational methods performed slightly better. Frequencies needed for both partition function calculations in transition-state theory and infrared intensities needed for radiative forcing estimates agreed well with experiment compared to other computational methods. A modified CBS-RAD method used to obtain energies led to superior results to all other previous heat of reaction estimates and most barrier height calculations when the B3LYP/6-311g** optimized geometry was used as the base structure. Use of the small-curvature tunneling correction and a hindered rotor treatment where appropriate led to accurate reaction rate constants and radiative forcing estimates without requiring any experimental data. Atmospheric lifetimes from theory at 277 K were indistinguishable from experimental results, as were the final global warming potentials compared to experiment. This is the first time entirely computational methods have been applied to estimate a global warming potential for a chemical, and we have found the approach to be robust, inexpensive, and accurate compared to prior experimental results. This methodology was subsequently used to estimate GWPs for three additional species [methane (CH(4)); fluoromethane (CH(3)F), or HFC-41; and fluoroform (CHF(3)), or HFC-23], where estimations also compare favorably to experimental values.

An Improved Swarm Optimization for Parameter Estimation and Biological Model Selection

PubMed Central

Abdullah, Afnizanfaizal; Deris, Safaai; Mohamad, Mohd Saberi; Anwar, Sohail

2013-01-01

One of the key aspects of computational systems biology is the investigation on the dynamic biological processes within cells. Computational models are often required to elucidate the mechanisms and principles driving the processes because of the nonlinearity and complexity. The models usually incorporate a set of parameters that signify the physical properties of the actual biological systems. In most cases, these parameters are estimated by fitting the model outputs with the corresponding experimental data. However, this is a challenging task because the available experimental data are frequently noisy and incomplete. In this paper, a new hybrid optimization method is proposed to estimate these parameters from the noisy and incomplete experimental data. The proposed method, called Swarm-based Chemical Reaction Optimization, integrates the evolutionary searching strategy employed by the Chemical Reaction Optimization, into the neighbouring searching strategy of the Firefly Algorithm method. The effectiveness of the method was evaluated using a simulated nonlinear model and two biological models: synthetic transcriptional oscillators, and extracellular protease production models. The results showed that the accuracy and computational speed of the proposed method were better than the existing Differential Evolution, Firefly Algorithm and Chemical Reaction Optimization methods. The reliability of the estimated parameters was statistically validated, which suggests that the model outputs produced by these parameters were valid even when noisy and incomplete experimental data were used. Additionally, Akaike Information Criterion was employed to evaluate the model selection, which highlighted the capability of the proposed method in choosing a plausible model based on the experimental data. In conclusion, this paper presents the effectiveness of the proposed method for parameter estimation and model selection problems using noisy and incomplete experimental data. This study is hoped to provide a new insight in developing more accurate and reliable biological models based on limited and low quality experimental data. PMID:23593445

Wildland fire probabilities estimated from weather model-deduced monthly mean fire danger indices

Treesearch

Haiganoush K. Preisler; Shyh-Chin Chen; Francis Fujioka; John W. Benoit; Anthony L. Westerling

2008-01-01

The National Fire Danger Rating System indices deduced from a regional simulation weather model were used to estimate probabilities and numbers of large fire events on monthly and 1-degree grid scales. The weather model simulations and forecasts are ongoing experimental products from the Experimental Climate Prediction Center at the Scripps Institution of Oceanography...

Sources of uncertainty in estimating stream solute export from headwater catchments at three sites

Treesearch

Ruth D. Yanai; Naoko Tokuchi; John L. Campbell; Mark B. Green; Eiji Matsuzaki; Stephanie N. Laseter; Cindi L. Brown; Amey S. Bailey; Pilar Lyons; Carrie R. Levine; Donald C. Buso; Gene E. Likens; Jennifer D. Knoepp; Keitaro Fukushima

2015-01-01

Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at the scale of a small-watershed ecosystem. We used data from the Gomadansan Experimental Forest, Japan, Hubbard Brook Experimental Forest, USA, and Coweeta Hydrologic Laboratory, USA, to evaluate many sources of uncertainty, including the precision and accuracy of...

Bias Corrections for Standardized Effect Size Estimates Used with Single-Subject Experimental Designs

ERIC Educational Resources Information Center

Ugille, Maaike; Moeyaert, Mariola; Beretvas, S. Natasha; Ferron, John M.; Van den Noortgate, Wim

2014-01-01

A multilevel meta-analysis can combine the results of several single-subject experimental design studies. However, the estimated effects are biased if the effect sizes are standardized and the number of measurement occasions is small. In this study, the authors investigated 4 approaches to correct for this bias. First, the standardized effect…

A data driven method for estimation of B(avail) and appK(D) using a single injection protocol with [¹¹C]raclopride in the mouse.

PubMed

Wimberley, Catriona J; Fischer, Kristina; Reilhac, Anthonin; Pichler, Bernd J; Gregoire, Marie Claude

2014-10-01

The partial saturation approach (PSA) is a simple, single injection experimental protocol that will estimate both B(avail) and appK(D) without the use of blood sampling. This makes it ideal for use in longitudinal studies of neurodegenerative diseases in the rodent. The aim of this study was to increase the range and applicability of the PSA by developing a data driven strategy for determining reliable regional estimates of receptor density (B(avail)) and in vivo affinity (1/appK(D)), and validate the strategy using a simulation model. The data driven method uses a time window guided by the dynamic equilibrium state of the system as opposed to using a static time window. To test the method, simulations of partial saturation experiments were generated and validated against experimental data. The experimental conditions simulated included a range of receptor occupancy levels and three different B(avail) and appK(D) values to mimic diseases states. Also the effect of using a reference region and typical PET noise on the stability and accuracy of the estimates was investigated. The investigations showed that the parameter estimates in a simulated healthy mouse, using the data driven method were within 10±30% of the simulated input for the range of occupancy levels simulated. Throughout all experimental conditions simulated, the accuracy and robustness of the estimates using the data driven method were much improved upon the typical method of using a static time window, especially at low receptor occupancy levels. Introducing a reference region caused a bias of approximately 10% over the range of occupancy levels. Based on extensive simulated experimental conditions, it was shown the data driven method provides accurate and precise estimates of B(avail) and appK(D) for a broader range of conditions compared to the original method. Copyright © 2014 Elsevier Inc. All rights reserved.

Experimental Bayesian Quantum Phase Estimation on a Silicon Photonic Chip.

PubMed

Paesani, S; Gentile, A A; Santagati, R; Wang, J; Wiebe, N; Tew, D P; O'Brien, J L; Thompson, M G

2017-03-10

Quantum phase estimation is a fundamental subroutine in many quantum algorithms, including Shor's factorization algorithm and quantum simulation. However, so far results have cast doubt on its practicability for near-term, nonfault tolerant, quantum devices. Here we report experimental results demonstrating that this intuition need not be true. We implement a recently proposed adaptive Bayesian approach to quantum phase estimation and use it to simulate molecular energies on a silicon quantum photonic device. The approach is verified to be well suited for prethreshold quantum processors by investigating its superior robustness to noise and decoherence compared to the iterative phase estimation algorithm. This shows a promising route to unlock the power of quantum phase estimation much sooner than previously believed.

Estimation of unsteady lift on a pitching airfoil from wake velocity surveys

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Panda, J.; Rumsey, C. L.

1993-01-01

The results of a joint experimental and computational study on the flowfield over a periodically pitched NACA0012 airfoil, and the resultant lift variation, are reported in this paper. The lift variation over a cycle of oscillation, and hence the lift hysteresis loop, is estimated from the velocity distribution in the wake measured or computed for successive phases of the cycle. Experimentally, the estimated lift hysteresis loops are compared with available data from the literature as well as with limited force balance measurements. Computationally, the estimated lift variations are compared with the corresponding variation obtained from the surface pressure distribution. Four analytical formulations for the lift estimation from wake surveys are considered and relative successes of the four are discussed.

Evaluation of General Classes of Reliability Estimators Often Used in Statistical Analyses of Quasi-Experimental Designs

NASA Astrophysics Data System (ADS)

Saini, K. K.; Sehgal, R. K.; Sethi, B. L.

2008-10-01

In this paper major reliability estimators are analyzed and there comparatively result are discussed. There strengths and weaknesses are evaluated in this case study. Each of the reliability estimators has certain advantages and disadvantages. Inter-rater reliability is one of the best ways to estimate reliability when your measure is an observation. However, it requires multiple raters or observers. As an alternative, you could look at the correlation of ratings of the same single observer repeated on two different occasions. Each of the reliability estimators will give a different value for reliability. In general, the test-retest and inter-rater reliability estimates will be lower in value than the parallel forms and internal consistency ones because they involve measuring at different times or with different raters. Since reliability estimates are often used in statistical analyses of quasi-experimental designs.

The effects of survey question wording on rape estimates: evidence from a quasi-experimental design.

PubMed

Fisher, Bonnie S

2009-02-01

The measurement of rape is among the leading methodological issues in the violence against women field. Methodological discussion continues to focus on decreasing measurement errors and improving the accuracy of rape estimates. The current study used a quasi-experimental design to examine the effect of survey question wording on estimates of completed and attempted rape and verbal threats of rape. Specifically, the study statistically compares self-reported rape estimates from two nationally representative studies of college women's sexual victimization experiences, the National College Women Sexual Victimization study and the National Violence Against College Women study. Results show significant differences between the two sets of rape estimates, with National Violence Against College Women study rape estimates ranging from 4.4% to 10.4% lower than the National College Women Sexual Victimization study rape estimates. Implications for future methodological research are discussed.

On the appropriateness of applying chi-square distribution based confidence intervals to spectral estimates of helicopter flyover data

NASA Technical Reports Server (NTRS)

Rutledge, Charles K.

1988-01-01

The validity of applying chi-square based confidence intervals to far-field acoustic flyover spectral estimates was investigated. Simulated data, using a Kendall series and experimental acoustic data from the NASA/McDonnell Douglas 500E acoustics test, were analyzed. Statistical significance tests to determine the equality of distributions of the simulated and experimental data relative to theoretical chi-square distributions were performed. Bias and uncertainty errors associated with the spectral estimates were easily identified from the data sets. A model relating the uncertainty and bias errors to the estimates resulted, which aided in determining the appropriateness of the chi-square distribution based confidence intervals. Such confidence intervals were appropriate for nontonally associated frequencies of the experimental data but were inappropriate for tonally associated estimate distributions. The appropriateness at the tonally associated frequencies was indicated by the presence of bias error and noncomformity of the distributions to the theoretical chi-square distribution. A technique for determining appropriate confidence intervals at the tonally associated frequencies was suggested.

Model-Based Estimation of Knee Stiffness

PubMed Central

Pfeifer, Serge; Vallery, Heike; Hardegger, Michael; Riener, Robert; Perreault, Eric J.

2013-01-01

During natural locomotion, the stiffness of the human knee is modulated continuously and subconsciously according to the demands of activity and terrain. Given modern actuator technology, powered transfemoral prostheses could theoretically provide a similar degree of sophistication and function. However, experimentally quantifying knee stiffness modulation during natural gait is challenging. Alternatively, joint stiffness could be estimated in a less disruptive manner using electromyography (EMG) combined with kinetic and kinematic measurements to estimate muscle force, together with models that relate muscle force to stiffness. Here we present the first step in that process, where we develop such an approach and evaluate it in isometric conditions, where experimental measurements are more feasible. Our EMG-guided modeling approach allows us to consider conditions with antagonistic muscle activation, a phenomenon commonly observed in physiological gait. Our validation shows that model-based estimates of knee joint stiffness coincide well with experimental data obtained using conventional perturbation techniques. We conclude that knee stiffness can be accurately estimated in isometric conditions without applying perturbations, which presents an important step towards our ultimate goal of quantifying knee stiffness during gait. PMID:22801482

Experimental Estimation of Mutation Rates in a Wheat Population With a Gene Genealogy Approach

PubMed Central

Raquin, Anne-Laure; Depaulis, Frantz; Lambert, Amaury; Galic, Nathalie; Brabant, Philippe; Goldringer, Isabelle

2008-01-01

Microsatellite markers are extensively used to evaluate genetic diversity in natural or experimental evolving populations. Their high degree of polymorphism reflects their high mutation rates. Estimates of the mutation rates are therefore necessary when characterizing diversity in populations. As a complement to the classical experimental designs, we propose to use experimental populations, where the initial state is entirely known and some intermediate states have been thoroughly surveyed, thus providing a short timescale estimation together with a large number of cumulated meioses. In this article, we derived four original gene genealogy-based methods to assess mutation rates with limited bias due to relevant model assumptions incorporating the initial state, the number of new alleles, and the genetic effective population size. We studied the evolution of genetic diversity at 21 microsatellite markers, after 15 generations in an experimental wheat population. Compared to the parents, 23 new alleles were found in generation 15 at 9 of the 21 loci studied. We provide evidence that they arose by mutation. Corresponding estimates of the mutation rates ranged from 0 to 4.97 × 10−3 per generation (i.e., year). Sequences of several alleles revealed that length polymorphism was only due to variation in the core of the microsatellite. Among different microsatellite characteristics, both the motif repeat number and an independent estimation of the Nei diversity were correlated with the novel diversity. Despite a reduced genetic effective size, global diversity at microsatellite markers increased in this population, suggesting that microsatellite diversity should be used with caution as an indicator in biodiversity conservation issues. PMID:18689900

Experimental estimation of mutation rates in a wheat population with a gene genealogy approach.

PubMed

Raquin, Anne-Laure; Depaulis, Frantz; Lambert, Amaury; Galic, Nathalie; Brabant, Philippe; Goldringer, Isabelle

2008-08-01

Microsatellite markers are extensively used to evaluate genetic diversity in natural or experimental evolving populations. Their high degree of polymorphism reflects their high mutation rates. Estimates of the mutation rates are therefore necessary when characterizing diversity in populations. As a complement to the classical experimental designs, we propose to use experimental populations, where the initial state is entirely known and some intermediate states have been thoroughly surveyed, thus providing a short timescale estimation together with a large number of cumulated meioses. In this article, we derived four original gene genealogy-based methods to assess mutation rates with limited bias due to relevant model assumptions incorporating the initial state, the number of new alleles, and the genetic effective population size. We studied the evolution of genetic diversity at 21 microsatellite markers, after 15 generations in an experimental wheat population. Compared to the parents, 23 new alleles were found in generation 15 at 9 of the 21 loci studied. We provide evidence that they arose by mutation. Corresponding estimates of the mutation rates ranged from 0 to 4.97 x 10(-3) per generation (i.e., year). Sequences of several alleles revealed that length polymorphism was only due to variation in the core of the microsatellite. Among different microsatellite characteristics, both the motif repeat number and an independent estimation of the Nei diversity were correlated with the novel diversity. Despite a reduced genetic effective size, global diversity at microsatellite markers increased in this population, suggesting that microsatellite diversity should be used with caution as an indicator in biodiversity conservation issues.

A new heat transfer analysis in machining based on two steps of 3D finite element modelling and experimental validation

NASA Astrophysics Data System (ADS)

Haddag, B.; Kagnaya, T.; Nouari, M.; Cutard, T.

2013-01-01

Modelling machining operations allows estimating cutting parameters which are difficult to obtain experimentally and in particular, include quantities characterizing the tool-workpiece interface. Temperature is one of these quantities which has an impact on the tool wear, thus its estimation is important. This study deals with a new modelling strategy, based on two steps of calculation, for analysis of the heat transfer into the cutting tool. Unlike the classical methods, considering only the cutting tool with application of an approximate heat flux at the cutting face, estimated from experimental data (e.g. measured cutting force, cutting power), the proposed approach consists of two successive 3D Finite Element calculations and fully independent on the experimental measurements; only the definition of the behaviour of the tool-workpiece couple is necessary. The first one is a 3D thermomechanical modelling of the chip formation process, which allows estimating cutting forces, chip morphology and its flow direction. The second calculation is a 3D thermal modelling of the heat diffusion into the cutting tool, by using an adequate thermal loading (applied uniform or non-uniform heat flux). This loading is estimated using some quantities obtained from the first step calculation, such as contact pressure, sliding velocity distributions and contact area. Comparisons in one hand between experimental data and the first calculation and at the other hand between measured temperatures with embedded thermocouples and the second calculation show a good agreement in terms of cutting forces, chip morphology and cutting temperature.

Solubility advantage of amorphous pharmaceuticals: II. Application of quantitative thermodynamic relationships for prediction of solubility enhancement in structurally diverse insoluble pharmaceuticals.

PubMed

Murdande, Sharad B; Pikal, Michael J; Shanker, Ravi M; Bogner, Robin H

2010-12-01

To quantitatively assess the solubility advantage of amorphous forms of nine insoluble drugs with a wide range of physico-chemical properties utilizing a previously reported thermodynamic approach. Thermal properties of amorphous and crystalline forms of drugs were measured using modulated differential calorimetry. Equilibrium moisture sorption uptake by amorphous drugs was measured by a gravimetric moisture sorption analyzer, and ionization constants were determined from the pH-solubility profiles. Solubilities of crystalline and amorphous forms of drugs were measured in de-ionized water at 25°C. Polarized microscopy was used to provide qualitative information about the crystallization of amorphous drug in solution during solubility measurement. For three out the nine compounds, the estimated solubility based on thermodynamic considerations was within two-fold of the experimental measurement. For one compound, estimated solubility enhancement was lower than experimental value, likely due to extensive ionization in solution and hence its sensitivity to error in pKa measurement. For the remaining five compounds, estimated solubility was about 4- to 53-fold higher than experimental results. In all cases where the theoretical solubility estimates were significantly higher, it was observed that the amorphous drug crystallized rapidly during the experimental determination of solubility, thus preventing an accurate experimental assessment of solubility advantage. It has been demonstrated that the theoretical approach does provide an accurate estimate of the maximum solubility enhancement by an amorphous drug relative to its crystalline form for structurally diverse insoluble drugs when recrystallization during dissolution is minimal.

A MATLAB toolbox for the efficient estimation of the psychometric function using the updated maximum-likelihood adaptive procedure.

PubMed

Shen, Yi; Dai, Wei; Richards, Virginia M

2015-03-01

A MATLAB toolbox for the efficient estimation of the threshold, slope, and lapse rate of the psychometric function is described. The toolbox enables the efficient implementation of the updated maximum-likelihood (UML) procedure. The toolbox uses an object-oriented architecture for organizing the experimental variables and computational algorithms, which provides experimenters with flexibility in experimental design and data management. Descriptions of the UML procedure and the UML Toolbox are provided, followed by toolbox use examples. Finally, guidelines and recommendations of parameter configurations are given.

Equation of State for RX-08-EL and RX-08-EP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, E.L.; Walton, J.

1985-05-07

JWL Equations of State (EOS's) have been estimated for RX-08-EL and RX-08-EP. The estimated JWL EOS parameters are listed. Previously, we derived a JWL EOS for RX-08-EN based on DYNA2D hydrodynamic code cylinder computations and comparisons with experimental cylinder test results are shown. The experimental cylinder shot results for RX-08-EL, shot K-473, were compared to the experimental cylinder shot results for RX-08-EN, shot K-463, as a reference. 10 figs., 6 tabs.

A Nonlinear Dynamics-Based Estimator for Functional Electrical Stimulation: Preliminary Results From Lower-Leg Extension Experiments.

PubMed

Allen, Marcus; Zhong, Qiang; Kirsch, Nicholas; Dani, Ashwin; Clark, William W; Sharma, Nitin

2017-12-01

Miniature inertial measurement units (IMUs) are wearable sensors that measure limb segment or joint angles during dynamic movements. However, IMUs are generally prone to drift, external magnetic interference, and measurement noise. This paper presents a new class of nonlinear state estimation technique called state-dependent coefficient (SDC) estimation to accurately predict joint angles from IMU measurements. The SDC estimation method uses limb dynamics, instead of limb kinematics, to estimate the limb state. Importantly, the nonlinear limb dynamic model is formulated into state-dependent matrices that facilitate the estimator design without performing a Jacobian linearization. The estimation method is experimentally demonstrated to predict knee joint angle measurements during functional electrical stimulation of the quadriceps muscle. The nonlinear knee musculoskeletal model was identified through a series of experiments. The SDC estimator was then compared with an extended kalman filter (EKF), which uses a Jacobian linearization and a rotation matrix method, which uses a kinematic model instead of the dynamic model. Each estimator's performance was evaluated against the true value of the joint angle, which was measured through a rotary encoder. The experimental results showed that the SDC estimator, the rotation matrix method, and EKF had root mean square errors of 2.70°, 2.86°, and 4.42°, respectively. Our preliminary experimental results show the new estimator's advantage over the EKF method but a slight advantage over the rotation matrix method. However, the information from the dynamic model allows the SDC method to use only one IMU to measure the knee angle compared with the rotation matrix method that uses two IMUs to estimate the angle.

Optimal Doppler centroid estimation for SAR data from a quasi-homogeneous source

NASA Technical Reports Server (NTRS)

Jin, M. Y.

1986-01-01

This correspondence briefly describes two Doppler centroid estimation (DCE) algorithms, provides a performance summary for these algorithms, and presents the experimental results. These algorithms include that of Li et al. (1985) and a newly developed one that is optimized for quasi-homogeneous sources. The performance enhancement achieved by the optimal DCE algorithm is clearly demonstrated by the experimental results.

Flumes, historic water yield and climatological data for Tenderfoot Creek Experimental Forest, Montana

Treesearch

Phillip E. Farnes; Ward W. McCaughey; Katherine J. Hansen

1999-01-01

The objectives of this Research Joint Venture Agreement (RJVA) were to install and calibrate three flumes on Tenderfoot Creek Experimental Forest (TCEF) in central Montana; check calibration of the existing seven flumes on TCEF; estimate the influence of fire on water yields over the 400-year fire history period; and estimate back records of monthly temperature,...

Estimating selection through male fitness: three complementary methods illuminate the nature and causes of selection on flowering time

PubMed Central

Austen, Emily J.; Weis, Arthur E.

2016-01-01

Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution. Selection differentials estimated by the first method disagreed with those estimated by the other two, indicating that mating opportunity was not the principal driver of selection on flowering time. The genetic and experimental evolution methods exhibited striking agreement overall, but a slight discrepancy between the two suggested that negative environmental covariance between age at flowering and male fitness may have contributed to phenotypic selection. Together, the three methods enriched our understanding of selection on flowering time, from mating opportunity to phenotypic selection to evolutionary response. The novel experimental evolution method may provide a means of examining selection through male fitness when genetic paternity analysis is not possible. PMID:26911957

Proposed method to estimate the liquid-vapor accommodation coefficient based on experimental sonoluminescence data.

PubMed

Puente, Gabriela F; Bonetto, Fabián J

2005-05-01

We used the temporal evolution of the bubble radius in single-bubble sonoluminescence to estimate the water liquid-vapor accommodation coefficient. The rapid changes in the bubble radius that occur during the bubble collapse and rebounds are a function of the actual value of the accommodation coefficient. We selected bubble radius measurements obtained from two different experimental techniques in conjunction with a robust parameter estimation strategy and we obtained that for water at room temperature the mass accommodation coefficient is in the confidence interval [0.217,0.329].

Development of advanced methods for analysis of experimental data in diffusion

NASA Astrophysics Data System (ADS)

Jaques, Alonso V.

There are numerous experimental configurations and data analysis techniques for the characterization of diffusion phenomena. However, the mathematical methods for estimating diffusivities traditionally do not take into account the effects of experimental errors in the data, and often require smooth, noiseless data sets to perform the necessary analysis steps. The current methods used for data smoothing require strong assumptions which can introduce numerical "artifacts" into the data, affecting confidence in the estimated parameters. The Boltzmann-Matano method is used extensively in the determination of concentration - dependent diffusivities, D(C), in alloys. In the course of analyzing experimental data, numerical integrations and differentiations of the concentration profile are performed. These methods require smoothing of the data prior to analysis. We present here an approach to the Boltzmann-Matano method that is based on a regularization method to estimate a differentiation operation on the data, i.e., estimate the concentration gradient term, which is important in the analysis process for determining the diffusivity. This approach, therefore, has the potential to be less subjective, and in numerical simulations shows an increased accuracy in the estimated diffusion coefficients. We present a regression approach to estimate linear multicomponent diffusion coefficients that eliminates the need pre-treat or pre-condition the concentration profile. This approach fits the data to a functional form of the mathematical expression for the concentration profile, and allows us to determine the diffusivity matrix directly from the fitted parameters. Reformulation of the equation for the analytical solution is done in order to reduce the size of the problem and accelerate the convergence. The objective function for the regression can incorporate point estimations for error in the concentration, improving the statistical confidence in the estimated diffusivity matrix. Case studies are presented to demonstrate the reliability and the stability of the method. To the best of our knowledge there is no published analysis of the effects of experimental errors on the reliability of the estimates for the diffusivities. For the case of linear multicomponent diffusion, we analyze the effects of the instrument analytical spot size, positioning uncertainty, and concentration uncertainty on the resulting values of the diffusivities. These effects are studied using Monte Carlo method on simulated experimental data. Several useful scaling relationships were identified which allow more rigorous and quantitative estimates of the errors in the measured data, and are valuable for experimental design. To further analyze anomalous diffusion processes, where traditional diffusional transport equations do not hold, we explore the use of fractional calculus in analytically representing these processes is proposed. We use the fractional calculus approach for anomalous diffusion processes occurring through a finite plane sheet with one face held at a fixed concentration, the other held at zero, and the initial concentration within the sheet equal to zero. This problem is related to cases in nature where diffusion is enhanced relative to the classical process, and the order of differentiation is not necessarily a second--order differential equation. That is, differentiation is of fractional order alpha, where 1 ≤ alpha < 2. For alpha = 2, the presented solutions reduce to the classical second-order diffusion solution for the conditions studied. The solution obtained allows the analysis of permeation experiments. Frequently, hydrogen diffusion is analyzed using electrochemical permeation methods using the traditional, Fickian-based theory. Experimental evidence shows the latter analytical approach is not always appropiate, because reported data shows qualitative (and quantitative) deviation from its theoretical scaling predictions. Preliminary analysis of data shows better agreement with fractional diffusion analysis when compared to traditional square-root scaling. Although there is a large amount of work in the estimation of the diffusivity from experimental data, reported studies typically present only the analytical description for the diffusivity, without scattering. However, because these studies do not consider effects produced by instrument analysis, their direct applicability is limited. We propose alternatives to address these, and to evaluate their influence on the final resulting diffusivity values.

The price elasticity of demand for heroin: Matched longitudinal and experimental evidence.

PubMed

Olmstead, Todd A; Alessi, Sheila M; Kline, Brendan; Pacula, Rosalie Liccardo; Petry, Nancy M

2015-05-01

This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately -0.80. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamic Testing of a Pre-stretched Flexible Tube for Identifying the Factors Affecting Modal Parameter Estimation

NASA Astrophysics Data System (ADS)

Unnikrishnan, Madhusudanan; Rajan, Akash; Basanthvihar Raghunathan, Binulal; Kochupillai, Jayaraj

2017-08-01

Experimental modal analysis is the primary tool for obtaining the fundamental dynamic characteristics like natural frequency, mode shape and modal damping ratio that determine the behaviour of any structure under dynamic loading conditions. This paper discusses about a carefully designed experimental method for calculating the dynamic characteristics of a pre-stretched horizontal flexible tube made of polyurethane material. The factors that affect the modal parameter estimation like the application time of shaker excitation, pause time between successive excitation cycles, averaging and windowing of measured signal, as well as the precautions to be taken during the experiment are explained in detail. The modal parameter estimation is done using MEscopeVESTM software. A finite element based pre-stressed modal analysis of the flexible tube is also done using ANSYS ver.14.0 software. The experimental and analytical results agreed well. The proposed experimental methodology may be extended for carrying out the modal analysis of many flexible structures like inflatables, tires and membranes.

Nickel-63 production in copper samples exposed to the Hiroshima atomic bomb: estimation based on an excitation function obtained by neutron irradiation experiments.

PubMed

Takamiya, K; Imanaka, T; Ota, Y; Akamine, M; Shibata, S; Shibata, T; Ito, Y; Imamura, M; Uwamino, Y; Nogawa, N; Baba, M; Iwasaki, S; Matsuyama, S

2008-07-01

The upper and lower limits of the excitation function of the (63)Cu(n,p)(63)Ni reaction were experimentally determined, and the number of (63)Ni nuclei produced in copper samples exposed to atomic bomb neutrons in Hiroshima was estimated by using the experimental excitation functions and the neutron fluences given in the DS02 dosimetry system. The estimated number of (63)Ni nuclei was compared with that measured and with that calculated using the DS02 dosimetry system and the corresponding ENDF/B-VI cross section. In comparison with DS02, there is about a 60% maximum difference in (63)Ni production at the hypocenter when the experimental upper cross section values are used. The difference becomes smaller at greater distances from the hypocenter and decreases, for example, to less than 30 and 5% when using the upper and lower experimental cross sections at 1,000 m, respectively.

Uncertainty Quantification and Statistical Convergence Guidelines for PIV Data

NASA Astrophysics Data System (ADS)

Stegmeir, Matthew; Kassen, Dan

2016-11-01

As Particle Image Velocimetry has continued to mature, it has developed into a robust and flexible technique for velocimetry used by expert and non-expert users. While historical estimates of PIV accuracy have typically relied heavily on "rules of thumb" and analysis of idealized synthetic images, recently increased emphasis has been placed on better quantifying real-world PIV measurement uncertainty. Multiple techniques have been developed to provide per-vector instantaneous uncertainty estimates for PIV measurements. Often real-world experimental conditions introduce complications in collecting "optimal" data, and the effect of these conditions is important to consider when planning an experimental campaign. The current work utilizes the results of PIV Uncertainty Quantification techniques to develop a framework for PIV users to utilize estimated PIV confidence intervals to compute reliable data convergence criteria for optimal sampling of flow statistics. Results are compared using experimental and synthetic data, and recommended guidelines and procedures leveraging estimated PIV confidence intervals for efficient sampling for converged statistics are provided.

Estimation of Supercapacitor Energy Storage Based on Fractional Differential Equations.

PubMed

Kopka, Ryszard

2017-12-22

In this paper, new results on using only voltage measurements on supercapacitor terminals for estimation of accumulated energy are presented. For this purpose, a study based on application of fractional-order models of supercapacitor charging/discharging circuits is undertaken. Parameter estimates of the models are then used to assess the amount of the energy accumulated in supercapacitor. The obtained results are compared with energy determined experimentally by measuring voltage and current on supercapacitor terminals. All the tests are repeated for various input signal shapes and parameters. Very high consistency between estimated and experimental results fully confirm suitability of the proposed approach and thus applicability of the fractional calculus to modelling of supercapacitor energy storage.

Environmental risk assessment of selected organic chemicals based on TOC test and QSAR estimation models.

PubMed

Chi, Yulang; Zhang, Huanteng; Huang, Qiansheng; Lin, Yi; Ye, Guozhu; Zhu, Huimin; Dong, Sijun

2018-02-01

Environmental risks of organic chemicals have been greatly determined by their persistence, bioaccumulation, and toxicity (PBT) and physicochemical properties. Major regulations in different countries and regions identify chemicals according to their bioconcentration factor (BCF) and octanol-water partition coefficient (Kow), which frequently displays a substantial correlation with the sediment sorption coefficient (Koc). Half-life or degradability is crucial for the persistence evaluation of chemicals. Quantitative structure activity relationship (QSAR) estimation models are indispensable for predicting environmental fate and health effects in the absence of field- or laboratory-based data. In this study, 39 chemicals of high concern were chosen for half-life testing based on total organic carbon (TOC) degradation, and two widely accepted and highly used QSAR estimation models (i.e., EPI Suite and PBT Profiler) were adopted for environmental risk evaluation. The experimental results and estimated data, as well as the two model-based results were compared, based on the water solubility, Kow, Koc, BCF and half-life. Environmental risk assessment of the selected compounds was achieved by combining experimental data and estimation models. It was concluded that both EPI Suite and PBT Profiler were fairly accurate in measuring the physicochemical properties and degradation half-lives for water, soil, and sediment. However, the half-lives between the experimental and the estimated results were still not absolutely consistent. This suggests deficiencies of the prediction models in some ways, and the necessity to combine the experimental data and predicted results for the evaluation of environmental fate and risks of pollutants. Copyright © 2016. Published by Elsevier B.V.

An estimate of the amount of road in the staggered-setting system of clearcutting.

Treesearch

Roy R. Silen; H.J. Gratkowski

1953-01-01

One question frequently asked by foresters in the Douglas-fir region is: "How much land is taken out of forest production by logging roads and landings?" The final answer is not known, but a rough estimate recently prepared for a sizable portion of the H. J. Andrews Experimental Forest may be useful as a tentative figure. The experimental area is located...

Using an Experimental Evaluation of Charter Schools to Test Whether Nonexperimental Comparison Group Methods Can Replicate Experimental Impact Estimates. NCEE 2012-4019

ERIC Educational Resources Information Center

Fortson, Kenneth; Verbitsky-Savitz, Natalya; Kopa, Emma; Gleason, Philip

2012-01-01

Randomized controlled trials (RCTs) are widely considered to be the gold standard in evaluating the impacts of a social program. When an RCT is infeasible, researchers often estimate program impacts by comparing outcomes of program participants with those of a nonexperimental comparison group, adjusting for observable differences between the two…

Dual Extended Kalman Filter for the Identification of Time-Varying Human Manual Control Behavior

NASA Technical Reports Server (NTRS)

Popovici, Alexandru; Zaal, Peter M. T.; Pool, Daan M.

2017-01-01

A Dual Extended Kalman Filter was implemented for the identification of time-varying human manual control behavior. Two filters that run concurrently were used, a state filter that estimates the equalization dynamics, and a parameter filter that estimates the neuromuscular parameters and time delay. Time-varying parameters were modeled as a random walk. The filter successfully estimated time-varying human control behavior in both simulated and experimental data. Simple guidelines are proposed for the tuning of the process and measurement covariance matrices and the initial parameter estimates. The tuning was performed on simulation data, and when applied on experimental data, only an increase in measurement process noise power was required in order for the filter to converge and estimate all parameters. A sensitivity analysis to initial parameter estimates showed that the filter is more sensitive to poor initial choices of neuromuscular parameters than equalization parameters, and bad choices for initial parameters can result in divergence, slow convergence, or parameter estimates that do not have a real physical interpretation. The promising results when applied to experimental data, together with its simple tuning and low dimension of the state-space, make the use of the Dual Extended Kalman Filter a viable option for identifying time-varying human control parameters in manual tracking tasks, which could be used in real-time human state monitoring and adaptive human-vehicle haptic interfaces.

Do bacterial cell numbers follow a theoretical Poisson distribution? Comparison of experimentally obtained numbers of single cells with random number generation via computer simulation.

PubMed

Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso; Koseki, Shigenobu

2016-12-01

We investigated a bacterial sample preparation procedure for single-cell studies. In the present study, we examined whether single bacterial cells obtained via 10-fold dilution followed a theoretical Poisson distribution. Four serotypes of Salmonella enterica, three serotypes of enterohaemorrhagic Escherichia coli and one serotype of Listeria monocytogenes were used as sample bacteria. An inoculum of each serotype was prepared via a 10-fold dilution series to obtain bacterial cell counts with mean values of one or two. To determine whether the experimentally obtained bacterial cell counts follow a theoretical Poisson distribution, a likelihood ratio test between the experimentally obtained cell counts and Poisson distribution which parameter estimated by maximum likelihood estimation (MLE) was conducted. The bacterial cell counts of each serotype sufficiently followed a Poisson distribution. Furthermore, to examine the validity of the parameters of Poisson distribution from experimentally obtained bacterial cell counts, we compared these with the parameters of a Poisson distribution that were estimated using random number generation via computer simulation. The Poisson distribution parameters experimentally obtained from bacterial cell counts were within the range of the parameters estimated using a computer simulation. These results demonstrate that the bacterial cell counts of each serotype obtained via 10-fold dilution followed a Poisson distribution. The fact that the frequency of bacterial cell counts follows a Poisson distribution at low number would be applied to some single-cell studies with a few bacterial cells. In particular, the procedure presented in this study enables us to develop an inactivation model at the single-cell level that can estimate the variability of survival bacterial numbers during the bacterial death process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atomistic determination of flexoelectric properties of crystalline dielectrics

NASA Astrophysics Data System (ADS)

Maranganti, R.; Sharma, P.

2009-08-01

Upon application of a uniform strain, internal sublattice shifts within the unit cell of a noncentrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk contribution can be characterized by means of a material property tensor called the bulk flexoelectric tensor. Several recent studies suggest that strain-gradient induced polarization may be responsible for a variety of interesting and anomalous electromechanical phenomena in materials including electromechanical coupling effects in nonuniformly strained nanostructures, “dead layer” effects in nanocapacitor systems, and “giant” piezoelectricity in perovskite nanostructures among others. In this work, adopting a lattice dynamics based microscopic approach we provide estimates of the flexoelectric tensor for certain cubic crystalline ionic salts, perovskite dielectrics, III-V and II-VI semiconductors. We compare our estimates with experimental/theoretical values wherever available and also revisit the validity of an existing empirical scaling relationship for the magnitude of flexoelectric coefficients in terms of material parameters. It is interesting to note that two independent groups report values of flexoelectric properties for perovskite dielectrics that are orders of magnitude apart: Cross and co-workers from Penn State have carried out experimental studies on a variety of materials including barium titanate while Catalan and co-workers from Cambridge used theoretical ab initio techniques as well as experimental techniques to study paraelectric strontium titanate as well as ferroelectric barium titanate and lead titanate. We find that, in the case of perovskite dielectrics, our estimates agree to an order of magnitude with the experimental and theoretical estimates for strontium titanate. For barium titanate however, while our estimates agree to an order of magnitude with existing ab initio calculations, there exists a large discrepancy with experimental estimates. The possible reasons for the observed deviations are discussed.

A MATLAB toolbox for the efficient estimation of the psychometric function using the updated maximum-likelihood adaptive procedure

PubMed Central

Richards, V. M.; Dai, W.

2014-01-01

A MATLAB toolbox for the efficient estimation of the threshold, slope, and lapse rate of the psychometric function is described. The toolbox enables the efficient implementation of the updated maximum-likelihood (UML) procedure. The toolbox uses an object-oriented architecture for organizing the experimental variables and computational algorithms, which provides experimenters with flexibility in experimental design and data management. Descriptions of the UML procedure and the UML Toolbox are provided, followed by toolbox use examples. Finally, guidelines and recommendations of parameter configurations are given. PMID:24671826

76 FR 25676 - Applications for New Awards; Technology and Media Services for Individuals With Disabilities...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-05

... research; quasi-experimental research; and other appropriate methods. The program of research and... designs such as quasi-experimental, single- subject, qualitative, and experimental research. This research.... Figlio, D.N., Rush, M. & Yin, L. (2010). Is it live or is it Internet? Experimental estimates of the...

Modelling of the UV Index on vertical and 40° tilted planes for different orientations.

PubMed

Serrano, D; Marín, M J; Utrillas, M P; Tena, F; Martínez-Lozano, J A

2012-02-01

In this study, estimated data of the UV Index on vertical planes are presented for the latitude of Valencia, Spain. For that purpose, the UVER values have been generated on vertical planes by means of four different geometrical models a) isotropic, b) Perez, c) Gueymard, d) Muneer, based on values of the global horizontal UVER and the diffuse horizontal UVER, measured experimentally. The UVER values, obtained by any model, overestimate the experimental values for all orientations, with the exception of the Perez model for the East plane. The results show statistical values of the MAD parameter (Mean Absolute Deviation) between 10% and 25%, the Perez model being the one that obtained a lower MAD for all levels. As for the statistic RMSD parameter (Root Mean Square Deviation), the results show values between 17% and 32%, and again the Perez model provides the best results in all vertical planes. The difference between the estimated UV Index and the experimental UV Index, for vertical and 40° tilted planes, was also calculated. 40° is an angle close to the latitude of Burjassot, Valencia, (39.5°), which, according to various studies, is the optimum angle to capture maximum radiation on tilted planes. We conclude that the models provide a good estimate of the UV Index, as they coincide or differ in one unit compared to the experimental values in 99% of cases, and this is valid for all orientations. Finally, we examined the relation between the UV Index on vertical and 40° tilted planes, both the experimental and estimated by the Perez model, and the experimental UV Index on a horizontal plane at 12 GMT. Based on the results, we can conclude that it is possible to estimate with a good approximation the UV Index on vertical and 40° tilted planes in different directions on the basis of the experimental horizontal UVI value, thus justifying the interest of this study. This journal is © The Royal Society of Chemistry and Owner Societies 2012

On experimental damage localization by SP2E: Application of H∞ estimation and oblique projections

NASA Astrophysics Data System (ADS)

Lenzen, Armin; Vollmering, Max

2018-05-01

In this article experimental damage localization based on H∞ estimation and state projection estimation error (SP2E) is studied. Based on an introduced difference process, a state space representation is derived for advantageous numerical solvability. Because real structural excitations are presumed to be unknown, a general input is applied therein, which allows synchronization and normalization. Furthermore, state projections are introduced to enhance damage identification. While first experiments to verify method SP2E have already been conducted and published, further laboratory results are analyzed here. Therefore, SP2E is used to experimentally localize stiffness degradations and mass alterations. Furthermore, the influence of projection techniques is analyzed. In summary, method SP2E is able to localize structural alterations, which has been observed by results of laboratory experiments.

Damage classification and estimation in experimental structures using time series analysis and pattern recognition

NASA Astrophysics Data System (ADS)

de Lautour, Oliver R.; Omenzetter, Piotr

2010-07-01

Developed for studying long sequences of regularly sampled data, time series analysis methods are being increasingly investigated for the use of Structural Health Monitoring (SHM). In this research, Autoregressive (AR) models were used to fit the acceleration time histories obtained from two experimental structures: a 3-storey bookshelf structure and the ASCE Phase II Experimental SHM Benchmark Structure, in undamaged and limited number of damaged states. The coefficients of the AR models were considered to be damage-sensitive features and used as input into an Artificial Neural Network (ANN). The ANN was trained to classify damage cases or estimate remaining structural stiffness. The results showed that the combination of AR models and ANNs are efficient tools for damage classification and estimation, and perform well using small number of damage-sensitive features and limited sensors.

Event-Based control of depth of hypnosis in anesthesia.

PubMed

Merigo, Luca; Beschi, Manuel; Padula, Fabrizio; Latronico, Nicola; Paltenghi, Massimiliano; Visioli, Antonio

2017-08-01

In this paper, we propose the use of an event-based control strategy for the closed-loop control of the depth of hypnosis in anesthesia by using propofol administration and the bispectral index as a controlled variable. A new event generator with high noise-filtering properties is employed in addition to a PIDPlus controller. The tuning of the parameters is performed off-line by using genetic algorithms by considering a given data set of patients. The effectiveness and robustness of the method is verified in simulation by implementing a Monte Carlo method to address the intra-patient and inter-patient variability. A comparison with a standard PID control structure shows that the event-based control system achieves a reduction of the total variation of the manipulated variable of 93% in the induction phase and of 95% in the maintenance phase. The use of event based automatic control in anesthesia yields a fast induction phase with bounded overshoot and an acceptable disturbance rejection. A comparison with a standard PID control structure shows that the technique effectively mimics the behavior of the anesthesiologist by providing a significant decrement of the total variation of the manipulated variable. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of burst suppression patterns in EEG using recurrence rate.

PubMed

Liang, Zhenhu; Wang, Yinghua; Ren, Yongshao; Li, Duan; Voss, Logan; Sleigh, Jamie; Li, Xiaoli

2014-01-01

Burst suppression is a unique electroencephalogram (EEG) pattern commonly seen in cases of severely reduced brain activity such as overdose of general anesthesia. It is important to detect burst suppression reliably during the administration of anesthetic or sedative agents, especially for cerebral-protective treatments in various neurosurgical diseases. This study investigates recurrent plot (RP) analysis for the detection of the burst suppression pattern (BSP) in EEG. The RP analysis is applied to EEG data containing BSPs collected from 14 patients. Firstly we obtain the best selection of parameters for RP analysis. Then, the recurrence rate (RR), determinism (DET), and entropy (ENTR) are calculated. Then RR was selected as the best BSP index one-way analysis of variance (ANOVA) and multiple comparison tests. Finally, the performance of RR analysis is compared with spectral analysis, bispectral analysis, approximate entropy, and the nonlinear energy operator (NLEO). ANOVA and multiple comparison tests showed that the RR could detect BSP and that it was superior to other measures with the highest sensitivity of suppression detection (96.49%, P = 0.03). Tracking BSP patterns is essential for clinical monitoring in critically ill and anesthetized patients. The purposed RR may provide an effective burst suppression detector for developing new patient monitoring systems.

[Assessing the depth-of-hypnosis].

PubMed

Høymork, Siv Cathrine

2010-03-25

There has been a breakthrough in the understanding of anaesthetic drug effects during the last two decades, and new monitors aimed at quantifying such effects have been developed. This review is based on publications from the last 15 years, oral presentations, and rewritten parts of the author's PhD thesis. General anaesthesia can be regarded as a combination of hypnosis (sleep), analgesia and muscle relaxation. Modern anaesthetic drugs aim at each of these effects separately. Pharmacological variation makes it impossible to find one dose suitable for all, so tools for measuring drug effects in the individual patient are warranted. Monitors for measuring depth-of-hypnosis and partly analgesic effect are commercially available. Among these, BIS (bispectral index), based on EEG, is by far the best documented. BIS is proven useful for preventing undesired awareness and overdosing, but there are major limitations. Use of such technology in clinical practice is under constant debate. Even though the BIS technology is promising and used widely, no health authorities have so far recommended that such monitors should be compulsory during general anaesthesia, but rather that it should be considered on an individual basis. So far, it seems like this is a sensible approach in Norway as well.

Photodetector development at Fraunhofer IAF: From LWIR to SWIR operating from cryogenic close to room temperature

NASA Astrophysics Data System (ADS)

Daumer, V.; Gramich, V.; Müller, R.; Schmidt, J.; Rutz, F.; Stadelmann, T.; Wörl, A.; Rehm, R.

2017-02-01

Photodetectors in the non-visible region of the electromagnetic spectrum are essential for security, defense and space science as well as industrial and scientific applications. The research activities at Fraunhofer IAF cover a broad range in the infrared (IR) regime. Whereas short-wavelength IR (SWIR, <1.7 μm) detectors are realized by InGaAs/InP structures, InAs/GaSb type-II superlattice (T2SL) infrared detectors are developed for the spectral bands from mid- (MWIR, 3-5 μm) to long-wavelength IR (LWIR, 8-12 μm). We report on the extension of the superlattice empirical pseudopotential method (SEPM) to 300 K for the design of LWIR heterostructures for operation near room temperature. Recently, we have also adapted heterostructure concepts to our well established bi-spectral T2SL MWIR detector resulting in a dark current density below 2 × 10-9 A/cm2 for a cut-off wavelength close to 5 μm. Finally, we present first results obtained with a gated viewing system based on our InGaAs/InAlAs/InP avalanche photodiode arrays.

Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission

NASA Astrophysics Data System (ADS)

Sáez-Cano, G.; Morales de los Ríos, J. A.; del Peral, L.; Neronov, A.; Wada, S.; Rodríguez Frías, M. D.

2015-03-01

The origin of cosmic rays have remained a mistery for more than a century. JEM-EUSO is a pioneer space-based telescope that will be located at the International Space Station (ISS) and its aim is to detect Ultra High Energy Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from upwards, and therefore, for a properly UHECR reconstruction under cloudy conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System (AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that will provide the cloud coverage and cloud top height in the JEM-EUSO Field of View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the direction it has been shot. In this paper we will explain the effects of clouds for the determination of the UHECR arrival direction. Moreover, since the cloud top height retrieval is crucial to analyze the UHECR and EHECR events under cloudy conditions, the retrieval algorithm that fulfills the technical requierements of the Infrared Camera of JEM-EUSO to reconstruct the cloud top height is presently reported.

General Anesthesia for a Patient With Pelizaeus-Merzbacher Disease.

PubMed

Kamekura, Nobuhito; Nitta, Yukie; Takuma, Shigeru; Fujisawa, Toshiaki

2016-01-01

We report the successful management of general anesthesia for a patient with Pelizaeus-Merzbacher disease (PMD). PMD is one of a group of progressive, degenerative disorders of the cerebral white matter. The typical clinical manifestations of PMD include psychomotor retardation, nystagmus, abnormal muscle tone, seizures, and cognitive impairment. General anesthesia for a patient with PMD may be difficult mainly because of seizures and airway complications related to poor pharyngeal muscle control. In addition, the possibility of exacerbation of spasticity should be considered. A 20-year-old man with PMD required removal of impacted wisdom teeth under general anesthesia. General anesthesia was induced with thiamylal, fentanyl, and desflurane. Anesthesia was maintained with desflurane and continuous intravenous remifentanil under bispectral index and train-of-4 monitoring. Anesthesia lasted 1 hour 20 minutes and was completed uneventfully. Airway complications, seizures, and exacerbation of spasticity did not occur postoperatively. Preoperatively, our patient had no history of epilepsy attacks or aspiration pneumonia, and no clinical symptoms of gastroesophageal reflux disease. Therefore, exacerbation of spasticity was one of the most likely potential complications. Identification of these associated conditions and evaluation of risk factors during preoperative examination is important for performing safe anesthesia in these patients.

Anesthetic depth and long-term survival: an update.

PubMed

Leslie, Kate; Short, Timothy G

2016-02-01

The purpose of this paper is to review the current evidence relating anesthetic depth to long-term survival after surgery. Using PubMed as the principal source, this review included published studies in all languages comparing mortality in patients with low- and high-processed electro-encephalo-graphic index values. All published studies used the bispectral index (BIS) monitor to measure anesthetic depth. The majority of the published observational studies were post hoc analyses of studies undertaken for other purposes. Most of these studies report a statistically significant association between deep general anesthesia (i.e., BIS values < 45) and death. Some studies also suggest an association between deep general anesthesia and myocardial infarction or postoperative cognitive decline. The combination of low BIS values and low delivered anesthetic concentrations (thus defining increased anesthetic sensitivity) may identify patients at particularly high risk. One of the three available randomized controlled trials reports worse outcomes in the BIS = 50 group compared with the BIS > 80 group, and two report no difference in mortality between the BIS = 35 and BIS = 50-55 groups. The available evidence on anesthetic depth and long-term survival is inconclusive. Randomized controlled trials with carefully controlled arterial blood pressure are required.

Field Validation of the Stability Limit of a Multi MW Turbine

NASA Astrophysics Data System (ADS)

Kallesøe, Bjarne S.; Kragh, Knud A.

2016-09-01

Long slender blades of modern multi-megawatt turbines exhibit a flutter like instability at rotor speeds above a critical rotor speed. Knowing the critical rotor speed is crucial to a safe turbine design. The flutter like instability can only be estimated using geometrically non-linear aeroelastic codes. In this study, the estimated rotor speed stability limit of a 7 MW state of the art wind turbine is validated experimentally. The stability limit is estimated using Siemens Wind Powers in-house aeroelastic code, and the results show that the predicted stability limit is within 5% of the experimentally observed limit.

Using Non-experimental Data to Estimate Treatment Effects

PubMed Central

Stuart, Elizabeth A.; Marcus, Sue M.; Horvitz-Lennon, Marcela V.; Gibbons, Robert D.; Normand, Sharon-Lise T.

2009-01-01

While much psychiatric research is based on randomized controlled trials (RCTs), where patients are randomly assigned to treatments, sometimes RCTs are not feasible. This paper describes propensity score approaches, which are increasingly used for estimating treatment effects in non-experimental settings. The primary goal of propensity score methods is to create sets of treated and comparison subjects who look as similar as possible, in essence replicating a randomized experiment, at least with respect to observed patient characteristics. A study to estimate the metabolic effects of antipsychotic medication in a sample of Florida Medicaid beneficiaries with schizophrenia illustrates methods. PMID:20563313

Damping in aerospace composite materials

NASA Astrophysics Data System (ADS)

Agneni, A.; Balis Crema, L.; Castellani, A.

Experimental results are presented on specimens of carbon and Kevlar fibers in epoxy resin, materials used in many aerospace structures (control surfaces and wings in aircraft, large antennas in spacecraft, etc.). Some experimental methods of estimating damping ratios are first reviewed, either in the time domain or in the frequency domain. Some damping factor estimates from experimental tests are then shown; in order to evaluate the effects of the aerospace environment, damping factors have been obtained in a typical range of temperature, namely between +120 C and -120 C, and in the pressure range from room pressure to 10 exp -6 torr. Finally, a theoretical approach for predicting the bounds of the damping coefficients is shown, and prediction data are compared with experimental results.

Test Equality between Three Treatments under an Incomplete Block Crossover Design.

PubMed

Lui, Kung-Jong

2015-01-01

Under a random effects linear additive risk model, we compare two experimental treatments with a placebo in continuous data under an incomplete block crossover trial. We develop three test procedures for simultaneously testing equality between two experimental treatments and a placebo, as well as interval estimators for the mean difference between treatments. We apply Monte Carlo simulations to evaluate the performance of these test procedures and interval estimators in a variety of situations. We note that the bivariate test procedure accounting for the dependence structure based on the F-test is preferable to the other two procedures when there is only one of the two experimental treatments has a non-zero effect vs. the placebo. We note further that when the effects of the two experimental treatments vs. a placebo are in the same relative directions and are approximately of equal magnitude, the summary test procedure based on a simple average of two weighted-least-squares (WLS) estimators can outperform the other two procedures with respect to power. When one of the two experimental treatments has a relatively large effect vs. the placebo, the univariate test procedure with using Bonferroni's equality can be still of use. Finally, we use the data about the forced expiratory volume in 1 s (FEV1) readings taken from a double-blind crossover trial comparing two different doses of formoterol with a placebo to illustrate the use of test procedures and interval estimators proposed here.

A Markerless 3D Computerized Motion Capture System Incorporating a Skeleton Model for Monkeys.

PubMed

Nakamura, Tomoya; Matsumoto, Jumpei; Nishimaru, Hiroshi; Bretas, Rafael Vieira; Takamura, Yusaku; Hori, Etsuro; Ono, Taketoshi; Nishijo, Hisao

2016-01-01

In this study, we propose a novel markerless motion capture system (MCS) for monkeys, in which 3D surface images of monkeys were reconstructed by integrating data from four depth cameras, and a skeleton model of the monkey was fitted onto 3D images of monkeys in each frame of the video. To validate the MCS, first, estimated 3D positions of body parts were compared between the 3D MCS-assisted estimation and manual estimation based on visual inspection when a monkey performed a shuttling behavior in which it had to avoid obstacles in various positions. The mean estimation error of the positions of body parts (3-14 cm) and of head rotation (35-43°) between the 3D MCS-assisted and manual estimation were comparable to the errors between two different experimenters performing manual estimation. Furthermore, the MCS could identify specific monkey actions, and there was no false positive nor false negative detection of actions compared with those in manual estimation. Second, to check the reproducibility of MCS-assisted estimation, the same analyses of the above experiments were repeated by a different user. The estimation errors of positions of most body parts between the two experimenters were significantly smaller in the MCS-assisted estimation than in the manual estimation. Third, effects of methamphetamine (MAP) administration on the spontaneous behaviors of four monkeys were analyzed using the MCS. MAP significantly increased head movements, tended to decrease locomotion speed, and had no significant effect on total path length. The results were comparable to previous human clinical data. Furthermore, estimated data following MAP injection (total path length, walking speed, and speed of head rotation) correlated significantly between the two experimenters in the MCS-assisted estimation (r = 0.863 to 0.999). The results suggest that the presented MCS in monkeys is useful in investigating neural mechanisms underlying various psychiatric disorders and developing pharmacological interventions.

Experimentally Estimated Impacts of School Vouchers on College Enrollment and Degree Attainment. Program on Education Policy and Governance Working Papers Series. PEPG 15-01

ERIC Educational Resources Information Center

Chingos, Matthew M.; Peterson, Paul E.

2015-01-01

We provide the first experimental estimates of the long-term impacts of a voucher to attend private school by linking data from a privately sponsored voucher initiative in New York City, which awarded the scholarships by lottery to low-income families, to administrative records on college enrollment and degree attainment. We find no significant…

Simulated maximum likelihood method for estimating kinetic rates in gene expression.

PubMed

Tian, Tianhai; Xu, Songlin; Gao, Junbin; Burrage, Kevin

2007-01-01

Kinetic rate in gene expression is a key measurement of the stability of gene products and gives important information for the reconstruction of genetic regulatory networks. Recent developments in experimental technologies have made it possible to measure the numbers of transcripts and protein molecules in single cells. Although estimation methods based on deterministic models have been proposed aimed at evaluating kinetic rates from experimental observations, these methods cannot tackle noise in gene expression that may arise from discrete processes of gene expression, small numbers of mRNA transcript, fluctuations in the activity of transcriptional factors and variability in the experimental environment. In this paper, we develop effective methods for estimating kinetic rates in genetic regulatory networks. The simulated maximum likelihood method is used to evaluate parameters in stochastic models described by either stochastic differential equations or discrete biochemical reactions. Different types of non-parametric density functions are used to measure the transitional probability of experimental observations. For stochastic models described by biochemical reactions, we propose to use the simulated frequency distribution to evaluate the transitional density based on the discrete nature of stochastic simulations. The genetic optimization algorithm is used as an efficient tool to search for optimal reaction rates. Numerical results indicate that the proposed methods can give robust estimations of kinetic rates with good accuracy.

The Limitations of Model-Based Experimental Design and Parameter Estimation in Sloppy Systems.

PubMed

White, Andrew; Tolman, Malachi; Thames, Howard D; Withers, Hubert Rodney; Mason, Kathy A; Transtrum, Mark K

2016-12-01

We explore the relationship among experimental design, parameter estimation, and systematic error in sloppy models. We show that the approximate nature of mathematical models poses challenges for experimental design in sloppy models. In many models of complex biological processes it is unknown what are the relevant physical mechanisms that must be included to explain system behaviors. As a consequence, models are often overly complex, with many practically unidentifiable parameters. Furthermore, which mechanisms are relevant/irrelevant vary among experiments. By selecting complementary experiments, experimental design may inadvertently make details that were ommitted from the model become relevant. When this occurs, the model will have a large systematic error and fail to give a good fit to the data. We use a simple hyper-model of model error to quantify a model's discrepancy and apply it to two models of complex biological processes (EGFR signaling and DNA repair) with optimally selected experiments. We find that although parameters may be accurately estimated, the discrepancy in the model renders it less predictive than it was in the sloppy regime where systematic error is small. We introduce the concept of a sloppy system-a sequence of models of increasing complexity that become sloppy in the limit of microscopic accuracy. We explore the limits of accurate parameter estimation in sloppy systems and argue that identifying underlying mechanisms controlling system behavior is better approached by considering a hierarchy of models of varying detail rather than focusing on parameter estimation in a single model.

Quantifying the effect of experimental design choices for in vitro scratch assays.

PubMed

Johnston, Stuart T; Ross, Joshua V; Binder, Benjamin J; Sean McElwain, D L; Haridas, Parvathi; Simpson, Matthew J

2016-07-07

Scratch assays are often used to investigate potential drug treatments for chronic wounds and cancer. Interpreting these experiments with a mathematical model allows us to estimate the cell diffusivity, D, and the cell proliferation rate, λ. However, the influence of the experimental design on the estimates of D and λ is unclear. Here we apply an approximate Bayesian computation (ABC) parameter inference method, which produces a posterior distribution of D and λ, to new sets of synthetic data, generated from an idealised mathematical model, and experimental data for a non-adhesive mesenchymal population of fibroblast cells. The posterior distribution allows us to quantify the amount of information obtained about D and λ. We investigate two types of scratch assay, as well as varying the number and timing of the experimental observations captured. Our results show that a scrape assay, involving one cell front, provides more precise estimates of D and λ, and is more computationally efficient to interpret than a wound assay, with two opposingly directed cell fronts. We find that recording two observations, after making the initial observation, is sufficient to estimate D and λ, and that the final observation time should correspond to the time taken for the cell front to move across the field of view. These results provide guidance for estimating D and λ, while simultaneously minimising the time and cost associated with performing and interpreting the experiment. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Limitations of Model-Based Experimental Design and Parameter Estimation in Sloppy Systems

PubMed Central

Tolman, Malachi; Thames, Howard D.; Mason, Kathy A.

2016-01-01

We explore the relationship among experimental design, parameter estimation, and systematic error in sloppy models. We show that the approximate nature of mathematical models poses challenges for experimental design in sloppy models. In many models of complex biological processes it is unknown what are the relevant physical mechanisms that must be included to explain system behaviors. As a consequence, models are often overly complex, with many practically unidentifiable parameters. Furthermore, which mechanisms are relevant/irrelevant vary among experiments. By selecting complementary experiments, experimental design may inadvertently make details that were ommitted from the model become relevant. When this occurs, the model will have a large systematic error and fail to give a good fit to the data. We use a simple hyper-model of model error to quantify a model’s discrepancy and apply it to two models of complex biological processes (EGFR signaling and DNA repair) with optimally selected experiments. We find that although parameters may be accurately estimated, the discrepancy in the model renders it less predictive than it was in the sloppy regime where systematic error is small. We introduce the concept of a sloppy system–a sequence of models of increasing complexity that become sloppy in the limit of microscopic accuracy. We explore the limits of accurate parameter estimation in sloppy systems and argue that identifying underlying mechanisms controlling system behavior is better approached by considering a hierarchy of models of varying detail rather than focusing on parameter estimation in a single model. PMID:27923060

It pays to compare: an experimental study on computational estimation.

PubMed

Star, Jon R; Rittle-Johnson, Bethany

2009-04-01

Comparing and contrasting examples is a core cognitive process that supports learning in children and adults across a variety of topics. In this experimental study, we evaluated the benefits of supporting comparison in a classroom context for children learning about computational estimation. Fifth- and sixth-grade students (N=157) learned about estimation either by comparing alternative solution strategies or by reflecting on the strategies one at a time. At posttest and retention test, students who compared were more flexible problem solvers on a variety of measures. Comparison also supported greater conceptual knowledge, but only for students who already knew some estimation strategies. These findings indicate that comparison is an effective learning and instructional practice in a domain with multiple acceptable answers.

Estimation of toxicity using the Toxicity Estimation Software Tool (TEST)

EPA Science Inventory

Tens of thousands of chemicals are currently in commerce, and hundreds more are introduced every year. Since experimental measurements of toxicity are extremely time consuming and expensive, it is imperative that alternative methods to estimate toxicity are developed.

Development of an extended Kalman filter for the self-sensing application of a spring-biased shape memory alloy wire actuator

NASA Astrophysics Data System (ADS)

Gurung, H.; Banerjee, A.

2016-02-01

This report presents the development of an extended Kalman filter (EKF) to harness the self-sensing capability of a shape memory alloy (SMA) wire, actuating a linear spring. The stress and temperature of the SMA wire, constituting the state of the system, are estimated using the EKF, from the measured change in electrical resistance (ER) of the SMA. The estimated stress is used to compute the change in length of the spring, eliminating the need for a displacement sensor. The system model used in the EKF comprises the heat balance equation and the constitutive relation of the SMA wire coupled with the force-displacement behavior of a spring. Both explicit and implicit approaches are adopted to evaluate the system model at each time-update step of the EKF. Next, in the measurement-update step, estimated states are updated based on the measured electrical resistance. It has been observed that for the same time step, the implicit approach consumes less computational time than the explicit method. To verify the implementation, EKF estimated states of the system are compared with those of an established model for different inputs to the SMA wire. An experimental setup is developed to measure the actual spring displacement and ER of the SMA, for any time-varying voltage applied to it. The process noise covariance is decided using a heuristic approach, whereas the measurement noise covariance is obtained experimentally. Finally, the EKF is used to estimate the spring displacement for a given input and the corresponding experimentally obtained ER of the SMA. The qualitative agreement between the EKF estimated displacement with that obtained experimentally reveals the true potential of this approach to harness the self-sensing capability of the SMA.

Estimates of Stellar Weak Interaction Rates for Nuclei in the Mass Range A=65-80

NASA Astrophysics Data System (ADS)

Pruet, Jason; Fuller, George M.

2003-11-01

We estimate lepton capture and emission rates, as well as neutrino energy loss rates, for nuclei in the mass range A=65-80. These rates are calculated on a temperature/density grid appropriate for a wide range of astrophysical applications including simulations of late time stellar evolution and X-ray bursts. The basic inputs in our single-particle and empirically inspired model are (i) experimentally measured level information, weak transition matrix elements, and lifetimes, (ii) estimates of matrix elements for allowed experimentally unmeasured transitions based on the systematics of experimentally observed allowed transitions, and (iii) estimates of the centroids of the GT resonances motivated by shell model calculations in the fp shell as well as by (n, p) and (p, n) experiments. Fermi resonances (isobaric analog states) are also included, and it is shown that Fermi transitions dominate the rates for most interesting proton-rich nuclei for which an experimentally determined ground state lifetime is unavailable. For the purposes of comparing our results with more detailed shell model based calculations we also calculate weak rates for nuclei in the mass range A=60-65 for which Langanke & Martinez-Pinedo have provided rates. The typical deviation in the electron capture and β-decay rates for these ~30 nuclei is less than a factor of 2 or 3 for a wide range of temperature and density appropriate for presupernova stellar evolution. We also discuss some subtleties associated with the partition functions used in calculations of stellar weak rates and show that the proper treatment of the partition functions is essential for estimating high-temperature β-decay rates. In particular, we show that partition functions based on unconverged Lanczos calculations can result in errors in estimates of high-temperature β-decay rates.

Equilibrium expert: an add-in to Microsoft Excel for multiple binding equilibrium simulations and parameter estimations.

PubMed

Raguin, Olivier; Gruaz-Guyon, Anne; Barbet, Jacques

2002-11-01

An add-in to Microsoft Excel was developed to simulate multiple binding equilibriums. A partition function, readily written even when the equilibrium is complex, describes the experimental system. It involves the concentrations of the different free molecular species and of the different complexes present in the experiment. As a result, the software is not restricted to a series of predefined experimental setups but can handle a large variety of problems involving up to nine independent molecular species. Binding parameters are estimated by nonlinear least-square fitting of experimental measurements as supplied by the user. The fitting process allows user-defined weighting of the experimental data. The flexibility of the software and the way it may be used to describe common experimental situations and to deal with usual problems such as tracer reactivity or nonspecific binding is demonstrated by a few examples. The software is available free of charge upon request.

A comparison of different synchronization measures in electroencephalogram during propofol anesthesia.

PubMed

Liang, Zhenhu; Ren, Ye; Yan, Jiaqing; Li, Duan; Voss, Logan J; Sleigh, Jamie W; Li, Xiaoli

2016-08-01

Electroencephalogram (EEG) synchronization is becoming an essential tool to describe neurophysiological mechanisms of communication between brain regions under general anesthesia. Different synchronization measures have their own properties to reflect the changes of EEG activities during different anesthetic states. However, the performance characteristics and the relations of different synchronization measures in evaluating synchronization changes during propofol-induced anesthesia are not fully elucidated. Two-channel EEG data from seven volunteers who had undergone a brief standardized propofol anesthesia were then adopted to calculate eight synchronization indexes. We computed the prediction probability (P K ) of synchronization indexes with Bispectral Index (BIS) and propofol effect-site concentration (C eff ) to quantify the ability of the indexes to predict BIS and C eff . Also, box plots and coefficient of variation were used to reflect the different synchronization changes and their robustness to noise in awake, unconscious and recovery states, and the Pearson correlation coefficient (R) was used for assessing the relationship among synchronization measures, BIS and C eff . Permutation cross mutual information (PCMI) and determinism (DET) could predict BIS and follow C eff better than nonlinear interdependence (NI), mutual information based on kernel estimation (KerMI) and cross correlation. Wavelet transform coherence (WTC) in α and β frequency bands followed BIS and C eff better than that in other frequency bands. There was a significant decrease in unconscious state and a significant increase in recovery state for PCMI and NI, while the trends were opposite for KerMI, DET and WTC. Phase synchronization based on phase locking value (PSPLV) in δ, θ, α and γ1 frequency bands dropped significantly in unconscious state, whereas it had no significant synchronization in recovery state. Moreover, PCMI, NI, DET correlated closely with each other and they had a better robustness to noise and higher correlation with BIS and C eff than other synchronization indexes. Propofol caused EEG synchronization changes during the anesthetic period. Different synchronization measures had individual properties in evaluating synchronization changes in different anesthetic states, which might be related to various forms of neural activities and neurophysiological mechanisms under general anesthesia.

"Zero ischemia" partial nephrectomy: novel laparoscopic and robotic technique.

PubMed

Gill, Inderbir S; Eisenberg, Manuel S; Aron, Monish; Berger, Andre; Ukimura, Osamu; Patil, Mukul B; Campese, Vito; Thangathurai, Duraiyah; Desai, Mihir M

2011-01-01

Ischemic injury impacts renal function outcomes following partial nephrectomy. Efforts to minimize, better yet, eliminate renal ischemia are imperative. Describe a novel technique of "zero ischemia" laparoscopic (LPN) and robotic-assisted (RAPN) partial nephrectomy. Data were prospectively collected into an institutional review board-approved database. Fifteen consecutive patients underwent zero ischemia procedures: LPN (n=12), RAPN (n=3). Included were all candidates for LPN or RAPN, irrespective of tumor complexity, including tumors that were central (n=9; 60%), hilar (n=1), in solitary kidney (n=1), in patients with chronic kidney disease grade 3 or greater (n=3). Anesthesia-related monitoring included pulmonary artery catheter (ie, Swan-Ganz), transesophageal echocardiography, cerebral oximetry, electroencephalographic bispectral index, mixed venous oxygen measurements, and vigorous hydration/diuresis. Pharmacologically induced hypotension was carefully timed to correspond with excision of the deepest aspect of the tumor. Renal parenchymal reconstruction was completed under normotension, ensuring complete hemostasis. Intraoperative and early postoperative data were collected prospectively. All cases were successfully completed without hilar clamping. Ischemia time was zero in all cases. Median tumor size was 2.5 cm (range: 1-4); operative time was 3 h (range: 1.3-6); blood loss was 150 ml (range: 20-400); and hospital stay was 3 d (range: 2-19). Nadir mean arterial pressure ranged from 52-65 mm Hg (median: 60), typically for 1-5 min. No patient had intraoperative transfusion or complication, acute or delayed renal hemorrhage, or hypotension-related sequelae. Postoperative complications (n=5) included urine retention (n=1), septicemia from presumed prostatitis (n=1), atrial fibrillation (n=1), urine leak (n=2). Pathology confirmed renal cell carcinoma in 13 patients (87%), all with negative margins. Median pre- and postoperative serum creatinine (0.9 mg/dl and 0.95 mg/dl, respectively) and estimated glomerular filtration rate (eGFR) (75.3 and 72.9, respectively) were comparable. Median absolute and percent change in discharge serum creatinine and eGFR were 0 and 0%, respectively. A novel zero ischemia technique for RAPN and LPN for substantial renal tumors is presented. The initial experience is encouraging. Copyright © 2010 European Association of Urology. Published by Elsevier B.V. All rights reserved.

[A first step towards safer sedation and analgesia: A systematic evaluation of outcomes and level of sedation and analgesia in the mechanically ventilated critically ill patient].

PubMed

Frade-Mera, M J; Regueiro-Díaz, N; Díaz-Castellano, L; Torres-Valverde, L; Alonso-Pérez, L; Landívar-Redondo, M M; Muñoz-Pasín, R; Terceros-Almanza, L J; Temprano-Vázquez, S; Sánchez-Izquierdo-Riera, J Á

Safe analgesia and sedation strategies are necessary in order to avoid under or over sedation, as well as improving the comfort and safety of critical care patients. To compare and contrast a multidisciplinary protocol of systematic evaluation and management of analgesia and sedation in a group of critical care patients on mechanical ventilation with the usual procedures. A cohort study with contemporary series was conducted in a tertiary care medical-surgical ICU February to November during 2013 and 2014. The inclusion criteria were mechanical ventilation ≥ 24h and use of sedation by continuous infusion. Sedation was monitored using the Richmond agitation-sedation scale or bispectral index, and analgesia were measured using the numeric rating scale, or behavioural indicators of pain scale. The study variables included; mechanical ventilation time, weaning time, ventilation support time, artificial airway time, continuous sedative infusion time, daily dose and frequency of analgesic and sedative drug use, hospital stay, and ICU and hospital mortality, Richmond agitation-sedation scale, bispectral index, numeric rating scale, and behavioural indicators of pain scale measurements. Kruskal Wallis and Chi 2 , and a significance of p<.05 were used. The study included 153 admissions, 75 pre-intervention and 78 post-intervention, with a mean age of 55.7±13 years old, and 67% men. Both groups showed similarities in age, reason for admission, and APACHE. There were non-significant decreases in mechanical ventilation time 4 (1.4-9.2) and 3.2 (1.4-8.1) days, respectively; p= 0.7, continuous sedative infusion time 6 (3-11) and 5 (3-11) days; p= 0.9, length of hospital stay 29 (18-52); 25 (14-41) days; p= 0.1, ICU mortality (8 vs. 5%; p= 0.4), and hospital mortality (10.6 vs. 9.4%: p= 0.8). Daily doses of midazolam and remifentanil decreased 347 (227-479) mg/day; 261 (159-358) mg/day; p= 0.02 and 2175 (1427-3285) mcg/day; 1500 (715-2740) mcg/day; p= 0.02, respectively. There were increases in the use of remifentanil (32% vs. 51%; p= 0.01), dexmedetomidine (0 vs.6%; p= 0.02), dexketoprofen (60 vs. 76%; p= 0.03), and haloperidol (15 vs.28%; p= 0.04). The use of morphine decreased (71 vs. 54%; p= 0.03). There was an increase in the number of measurements and Richmond agitation-sedation scale scores 6 (3-17); 21 (9-39); p< 0.0001, behavioural indicators of pain scale 6 (3-18); 19(8-33); p< 0.001 and numeric rating scale 4 (2-6); 8 (6-17); p< 0.0001. The implementation of a multidisciplinary protocol of systematic evaluation of analgesia and sedation management achieved an improvement in monitoring and adequacy of dose to patient needs, leading to improved outcomes. Copyright © 2015 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Intravenous Anesthesia With Bispectral Index Monitoring vs Inhalational Anesthesia for Rhytidoplasty: A Randomized Clinical Trial.

PubMed

Jones, Kristin A; LaFerriere, Keith A

2015-01-01

Minor adverse effects related to anesthesia are common and worrisome to patients, including perioperative vomiting, gagging on the endotracheal tube, incisional pain, and nausea. A previously published intravenous anesthesia protocol reports extremely low rates of postoperative nausea and vomiting (<1%) and decreases in postoperative pain perception compared with rates reported following administration of inhalational anesthetics. To evaluate and compare postoperative outcomes in patients after administration of combined propofol and ketamine hydrochloride anesthesia with bispectral index monitoring (PKA-BIS protocol) vs inhalational anesthesia (IA) during lower rhytidoplasty. We performed a prospective, double-blind, randomized comparison trial of the PKA-BIS protocol and IA in 30 consecutive female patients undergoing rhytidoplasty by a single surgeon at a single outpatient surgery center from October 2013 to June 2014. Outcome measures included nausea, vomiting, pain, overall feeling of well-being, time to awaken, time to discharge, and cost. Patient measures were recorded using a combination of a 40-item validated postoperative quality of recovery questionnaire (QOR-40) and visual analog scales (VASs). Results were recorded immediately after surgery and on postoperative days 1 and 7. A statistically significant reduction in emergence time (mean [SD], 29.8 [10.6] vs 46.0 [10.2] minutes; P < .001) and time to meet discharge criteria (51.4 [19.3] vs 66.1 [12.9] minutes; P = .02) was seen in patients in the PKA-BIS group. Patient-reported (subjective) postoperative nausea (3 of 15 [20%] vs 7 of 15 patients [47%]; P = .12; χ2 = 2.40), vomiting (0 vs 2 of 15 patients [13%]; P = .14; χ2 = 2.14), and confusion on the day of surgery (3 of 15 [20%] vs 6 of 14 patients [43%]; P = .18; χ2 = 1.77) were also decreased in the PKA-BIS group, but these differences did not reach significance. Differences in global recovery scores (QOR-40 scores in the postanesthesia care unit, 158.13 [22.68] vs 155.33 [18.09]; P = .71; at day 1, 166.47 [26.39] vs 166.00 [16.00]; P = .96), postoperative overall feeling of well-being (VAS scores at day 1, 6.10 vs 6.26; at day 7, 7.49 vs 8.00), and postoperative pain perception (VAS scores at day 1, 3.40 vs 3.65; at day 7, 2.26 vs 1.81) between the PKA-BIS and IA groups, respectively, did not reach significance. The costs of anesthesia administration were similar between the PKA-BIS ($10.37/h) and IA ($8.47/h to $9.87/h) groups. The PKA-BIS protocol for anesthesia appears to be a comparable alternative to traditional IA in patients undergoing elective rhytidoplasty. A larger patient sample size is needed to determine whether trends toward decreased nausea, vomiting, and postoperative confusion and differences in postoperative pain perception are significant. clinicaltrials.gov Identifier: NCT02410460. 1.

Link-state-estimation-based transmission power control in wireless body area networks.

PubMed

Kim, Seungku; Eom, Doo-Seop

2014-07-01

This paper presents a novel transmission power control protocol to extend the lifetime of sensor nodes and to increase the link reliability in wireless body area networks (WBANs). We first experimentally investigate the properties of the link states using the received signal strength indicator (RSSI). We then propose a practical transmission power control protocol based on both short- and long-term link-state estimations. Both the short- and long-term link-state estimations enable the transceiver to adapt the transmission power level and target the RSSI threshold range, respectively, to simultaneously satisfy the requirements of energy efficiency and link reliability. Finally, the performance of the proposed protocol is experimentally evaluated in two experimental scenarios-body posture change and dynamic body motion-and compared with the typical WBAN transmission power control protocols, a real-time reactive scheme, and a dynamic postural position inference mechanism. From the experimental results, it is found that the proposed protocol increases the lifetime of the sensor nodes by a maximum of 9.86% and enhances the link reliability by reducing the packet loss by a maximum of 3.02%.

Estimation of sample size and testing power (part 6).

PubMed

Hu, Liang-ping; Bao, Xiao-lei; Guan, Xue; Zhou, Shi-guo

2012-03-01

The design of one factor with k levels (k ≥ 3) refers to the research that only involves one experimental factor with k levels (k ≥ 3), and there is no arrangement for other important non-experimental factors. This paper introduces the estimation of sample size and testing power for quantitative data and qualitative data having a binary response variable with the design of one factor with k levels (k ≥ 3).

The search for causal inferences: using propensity scores post hoc to reduce estimation error with nonexperimental research.

PubMed

Tumlinson, Samuel E; Sass, Daniel A; Cano, Stephanie M

2014-03-01

While experimental designs are regarded as the gold standard for establishing causal relationships, such designs are usually impractical owing to common methodological limitations. The objective of this article is to illustrate how propensity score matching (PSM) and using propensity scores (PS) as a covariate are viable alternatives to reduce estimation error when experimental designs cannot be implemented. To mimic common pediatric research practices, data from 140 simulated participants were used to resemble an experimental and nonexperimental design that assessed the effect of treatment status on participant weight loss for diabetes. Pretreatment participant characteristics (age, gender, physical activity, etc.) were then used to generate PS for use in the various statistical approaches. Results demonstrate how PSM and using the PS as a covariate can be used to reduce estimation error and improve statistical inferences. References for issues related to the implementation of these procedures are provided to assist researchers.

Estimation of sample size and testing power (Part 3).

PubMed

Hu, Liang-ping; Bao, Xiao-lei; Guan, Xue; Zhou, Shi-guo

2011-12-01

This article introduces the definition and sample size estimation of three special tests (namely, non-inferiority test, equivalence test and superiority test) for qualitative data with the design of one factor with two levels having a binary response variable. Non-inferiority test refers to the research design of which the objective is to verify that the efficacy of the experimental drug is not clinically inferior to that of the positive control drug. Equivalence test refers to the research design of which the objective is to verify that the experimental drug and the control drug have clinically equivalent efficacy. Superiority test refers to the research design of which the objective is to verify that the efficacy of the experimental drug is clinically superior to that of the control drug. By specific examples, this article introduces formulas of sample size estimation for the three special tests, and their SAS realization in detail.

A new mathematical approach for the estimation of the AUC and its variability under different experimental designs in preclinical studies.

PubMed

Navarro-Fontestad, Carmen; González-Álvarez, Isabel; Fernández-Teruel, Carlos; Bermejo, Marival; Casabó, Vicente Germán

2012-01-01

The aim of the present work was to develop a new mathematical method for estimating the area under the curve (AUC) and its variability that could be applied in different preclinical experimental designs and amenable to be implemented in standard calculation worksheets. In order to assess the usefulness of the new approach, different experimental scenarios were studied and the results were compared with those obtained with commonly used software: WinNonlin® and Phoenix WinNonlin®. The results do not show statistical differences among the AUC values obtained by both procedures, but the new method appears to be a better estimator of the AUC standard error, measured as the coverage of 95% confidence interval. In this way, the new proposed method demonstrates to be as useful as WinNonlin® software when it was applicable. Copyright © 2011 John Wiley & Sons, Ltd.

Estimating peer effects in networks with peer encouragement designs.

PubMed

Eckles, Dean; Kizilcec, René F; Bakshy, Eytan

2016-07-05

Peer effects, in which the behavior of an individual is affected by the behavior of their peers, are central to social science. Because peer effects are often confounded with homophily and common external causes, recent work has used randomized experiments to estimate effects of specific peer behaviors. These experiments have often relied on the experimenter being able to randomly modulate mechanisms by which peer behavior is transmitted to a focal individual. We describe experimental designs that instead randomly assign individuals' peers to encouragements to behaviors that directly affect those individuals. We illustrate this method with a large peer encouragement design on Facebook for estimating the effects of receiving feedback from peers on posts shared by focal individuals. We find evidence for substantial effects of receiving marginal feedback on multiple behaviors, including giving feedback to others and continued posting. These findings provide experimental evidence for the role of behaviors directed at specific individuals in the adoption and continued use of communication technologies. In comparison, observational estimates differ substantially, both underestimating and overestimating effects, suggesting that researchers and policy makers should be cautious in relying on them.

Estimating peer effects in networks with peer encouragement designs

PubMed Central

Eckles, Dean; Kizilcec, René F.; Bakshy, Eytan

2016-01-01

Peer effects, in which the behavior of an individual is affected by the behavior of their peers, are central to social science. Because peer effects are often confounded with homophily and common external causes, recent work has used randomized experiments to estimate effects of specific peer behaviors. These experiments have often relied on the experimenter being able to randomly modulate mechanisms by which peer behavior is transmitted to a focal individual. We describe experimental designs that instead randomly assign individuals’ peers to encouragements to behaviors that directly affect those individuals. We illustrate this method with a large peer encouragement design on Facebook for estimating the effects of receiving feedback from peers on posts shared by focal individuals. We find evidence for substantial effects of receiving marginal feedback on multiple behaviors, including giving feedback to others and continued posting. These findings provide experimental evidence for the role of behaviors directed at specific individuals in the adoption and continued use of communication technologies. In comparison, observational estimates differ substantially, both underestimating and overestimating effects, suggesting that researchers and policy makers should be cautious in relying on them. PMID:27382145

Set-base dynamical parameter estimation and model invalidation for biochemical reaction networks.

PubMed

Rumschinski, Philipp; Borchers, Steffen; Bosio, Sandro; Weismantel, Robert; Findeisen, Rolf

2010-05-25

Mathematical modeling and analysis have become, for the study of biological and cellular processes, an important complement to experimental research. However, the structural and quantitative knowledge available for such processes is frequently limited, and measurements are often subject to inherent and possibly large uncertainties. This results in competing model hypotheses, whose kinetic parameters may not be experimentally determinable. Discriminating among these alternatives and estimating their kinetic parameters is crucial to improve the understanding of the considered process, and to benefit from the analytical tools at hand. In this work we present a set-based framework that allows to discriminate between competing model hypotheses and to provide guaranteed outer estimates on the model parameters that are consistent with the (possibly sparse and uncertain) experimental measurements. This is obtained by means of exact proofs of model invalidity that exploit the polynomial/rational structure of biochemical reaction networks, and by making use of an efficient strategy to balance solution accuracy and computational effort. The practicability of our approach is illustrated with two case studies. The first study shows that our approach allows to conclusively rule out wrong model hypotheses. The second study focuses on parameter estimation, and shows that the proposed method allows to evaluate the global influence of measurement sparsity, uncertainty, and prior knowledge on the parameter estimates. This can help in designing further experiments leading to improved parameter estimates.

Set-base dynamical parameter estimation and model invalidation for biochemical reaction networks

PubMed Central

2010-01-01

Background Mathematical modeling and analysis have become, for the study of biological and cellular processes, an important complement to experimental research. However, the structural and quantitative knowledge available for such processes is frequently limited, and measurements are often subject to inherent and possibly large uncertainties. This results in competing model hypotheses, whose kinetic parameters may not be experimentally determinable. Discriminating among these alternatives and estimating their kinetic parameters is crucial to improve the understanding of the considered process, and to benefit from the analytical tools at hand. Results In this work we present a set-based framework that allows to discriminate between competing model hypotheses and to provide guaranteed outer estimates on the model parameters that are consistent with the (possibly sparse and uncertain) experimental measurements. This is obtained by means of exact proofs of model invalidity that exploit the polynomial/rational structure of biochemical reaction networks, and by making use of an efficient strategy to balance solution accuracy and computational effort. Conclusions The practicability of our approach is illustrated with two case studies. The first study shows that our approach allows to conclusively rule out wrong model hypotheses. The second study focuses on parameter estimation, and shows that the proposed method allows to evaluate the global influence of measurement sparsity, uncertainty, and prior knowledge on the parameter estimates. This can help in designing further experiments leading to improved parameter estimates. PMID:20500862

Exact dimension estimation of interacting qubit systems assisted by a single quantum probe

NASA Astrophysics Data System (ADS)

Sone, Akira; Cappellaro, Paola

2017-12-01

Estimating the dimension of an Hilbert space is an important component of quantum system identification. In quantum technologies, the dimension of a quantum system (or its corresponding accessible Hilbert space) is an important resource, as larger dimensions determine, e.g., the performance of quantum computation protocols or the sensitivity of quantum sensors. Despite being a critical task in quantum system identification, estimating the Hilbert space dimension is experimentally challenging. While there have been proposals for various dimension witnesses capable of putting a lower bound on the dimension from measuring collective observables that encode correlations, in many practical scenarios, especially for multiqubit systems, the experimental control might not be able to engineer the required initialization, dynamics, and observables. Here we propose a more practical strategy that relies not on directly measuring an unknown multiqubit target system, but on the indirect interaction with a local quantum probe under the experimenter's control. Assuming only that the interaction model is given and the evolution correlates all the qubits with the probe, we combine a graph-theoretical approach and realization theory to demonstrate that the system dimension can be exactly estimated from the model order of the system. We further analyze the robustness in the presence of background noise of the proposed estimation method based on realization theory, finding that despite stringent constrains on the allowed noise level, exact dimension estimation can still be achieved.

Nematode Damage Functions: The Problems of Experimental and Sampling Error

PubMed Central

Ferris, H.

1984-01-01

The development and use of pest damage functions involves measurement and experimental errors associated with cultural, environmental, and distributional factors. Damage predictions are more valuable if considered with associated probability. Collapsing population densities into a geometric series of population classes allows a pseudo-replication removal of experimental and sampling error in damage function development. Recognition of the nature of sampling error for aggregated populations allows assessment of probability associated with the population estimate. The product of the probabilities incorporated in the damage function and in the population estimate provides a basis for risk analysis of the yield loss prediction and the ensuing management decision. PMID:19295865

Estimation of the outer-sphere contribution to the activation volume for electron exchange reactions using the mean spherical approximation

NASA Astrophysics Data System (ADS)

Takagi, Hideo D.; Swaddle, Thomas W.

1996-01-01

The outer-sphere contribution to the volume of activation of homogeneous electron exchange reactions is estimated for selected solvents on the basis of the mean spherical approximation (MSA), and the calculated values are compared with those estimated by the Strank-Hush-Marcus (SHM) theory and with activation volumes obtained experimentally for the electron exchange reaction between tris(hexafluoroacetylacetonato)ruthenium(III) and -(II) in acetone, acetonitrile, methanol and chloroform. The MSA treatment, which recognizes the molecular nature of the solvent, does not improve significantly upon the continuous-dielectric SHM theory, which represents the experimental data adequately for the more polar solvents.

Estimating Coherence Measures from Limited Experimental Data Available

NASA Astrophysics Data System (ADS)

Zhang, Da-Jian; Liu, C. L.; Yu, Xiao-Dong; Tong, D. M.

2018-04-01

Quantifying coherence has received increasing attention, and considerable work has been directed towards finding coherence measures. While various coherence measures have been proposed in theory, an important issue following is how to estimate these coherence measures in experiments. This is a challenging task, since the state of a system is often unknown in practical applications and the accessible measurements in a real experiment are typically limited. In this Letter, we put forward an approach to estimate coherence measures of an unknown state from any limited experimental data available. Our approach is not only applicable to coherence measures but can be extended to other resource measures.

Estimation of channel parameters and background irradiance for free-space optical link.

PubMed

Khatoon, Afsana; Cowley, William G; Letzepis, Nick; Giggenbach, Dirk

2013-05-10

Free-space optical communication can experience severe fading due to optical scintillation in long-range links. Channel estimation is also corrupted by background and electrical noise. Accurate estimation of channel parameters and scintillation index (SI) depends on perfect removal of background irradiance. In this paper, we propose three different methods, the minimum-value (MV), mean-power (MP), and maximum-likelihood (ML) based methods, to remove the background irradiance from channel samples. The MV and MP methods do not require knowledge of the scintillation distribution. While the ML-based method assumes gamma-gamma scintillation, it can be easily modified to accommodate other distributions. Each estimator's performance is compared using simulation data as well as experimental measurements. The estimators' performance are evaluated from low- to high-SI areas using simulation data as well as experimental trials. The MV and MP methods have much lower complexity than the ML-based method. However, the ML-based method shows better SI and background-irradiance estimation performance.

Kalman filter approach for uncertainty quantification in time-resolved laser-induced incandescence.

PubMed

Hadwin, Paul J; Sipkens, Timothy A; Thomson, Kevin A; Liu, Fengshan; Daun, Kyle J

2018-03-01

Time-resolved laser-induced incandescence (TiRe-LII) data can be used to infer spatially and temporally resolved volume fractions and primary particle size distributions of soot-laden aerosols, but these estimates are corrupted by measurement noise as well as uncertainties in the spectroscopic and heat transfer submodels used to interpret the data. Estimates of the temperature, concentration, and size distribution of soot primary particles within a sample aerosol are typically made by nonlinear regression of modeled spectral incandescence decay, or effective temperature decay, to experimental data. In this work, we employ nonstationary Bayesian estimation techniques to infer aerosol properties from simulated and experimental LII signals, specifically the extended Kalman filter and Schmidt-Kalman filter. These techniques exploit the time-varying nature of both the measurements and the models, and they reveal how uncertainty in the estimates computed from TiRe-LII data evolves over time. Both techniques perform better when compared with standard deterministic estimates; however, we demonstrate that the Schmidt-Kalman filter produces more realistic uncertainty estimates.

Mixing soil samples across experimental units ignores uncertainty and generates falsely precise estimates of soil biota effects on plants

USDA-ARS?s Scientific Manuscript database

A number of recent soil biota studies have deviated from the standard experimental approach of generating a distinct data value for each experimental unit (e.g. Yang et al., 2013; Gundale et al., 2014). Instead, these studies have mixed together soils from multiple experimental units (i.e. sites wi...

Simultaneous versus sequential optimal experiment design for the identification of multi-parameter microbial growth kinetics as a function of temperature.

PubMed

Van Derlinden, E; Bernaerts, K; Van Impe, J F

2010-05-21

Optimal experiment design for parameter estimation (OED/PE) has become a popular tool for efficient and accurate estimation of kinetic model parameters. When the kinetic model under study encloses multiple parameters, different optimization strategies can be constructed. The most straightforward approach is to estimate all parameters simultaneously from one optimal experiment (single OED/PE strategy). However, due to the complexity of the optimization problem or the stringent limitations on the system's dynamics, the experimental information can be limited and parameter estimation convergence problems can arise. As an alternative, we propose to reduce the optimization problem to a series of two-parameter estimation problems, i.e., an optimal experiment is designed for a combination of two parameters while presuming the other parameters known. Two different approaches can be followed: (i) all two-parameter optimal experiments are designed based on identical initial parameter estimates and parameters are estimated simultaneously from all resulting experimental data (global OED/PE strategy), and (ii) optimal experiments are calculated and implemented sequentially whereby the parameter values are updated intermediately (sequential OED/PE strategy). This work exploits OED/PE for the identification of the Cardinal Temperature Model with Inflection (CTMI) (Rosso et al., 1993). This kinetic model describes the effect of temperature on the microbial growth rate and encloses four parameters. The three OED/PE strategies are considered and the impact of the OED/PE design strategy on the accuracy of the CTMI parameter estimation is evaluated. Based on a simulation study, it is observed that the parameter values derived from the sequential approach deviate more from the true parameters than the single and global strategy estimates. The single and global OED/PE strategies are further compared based on experimental data obtained from design implementation in a bioreactor. Comparable estimates are obtained, but global OED/PE estimates are, in general, more accurate and reliable. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Experimental Design for Stochastic Models of Nonlinear Signaling Pathways Using an Interval-Wise Linear Noise Approximation and State Estimation.

PubMed

Zimmer, Christoph

2016-01-01

Computational modeling is a key technique for analyzing models in systems biology. There are well established methods for the estimation of the kinetic parameters in models of ordinary differential equations (ODE). Experimental design techniques aim at devising experiments that maximize the information encoded in the data. For ODE models there are well established approaches for experimental design and even software tools. However, data from single cell experiments on signaling pathways in systems biology often shows intrinsic stochastic effects prompting the development of specialized methods. While simulation methods have been developed for decades and parameter estimation has been targeted for the last years, only very few articles focus on experimental design for stochastic models. The Fisher information matrix is the central measure for experimental design as it evaluates the information an experiment provides for parameter estimation. This article suggest an approach to calculate a Fisher information matrix for models containing intrinsic stochasticity and high nonlinearity. The approach makes use of a recently suggested multiple shooting for stochastic systems (MSS) objective function. The Fisher information matrix is calculated by evaluating pseudo data with the MSS technique. The performance of the approach is evaluated with simulation studies on an Immigration-Death, a Lotka-Volterra, and a Calcium oscillation model. The Calcium oscillation model is a particularly appropriate case study as it contains the challenges inherent to signaling pathways: high nonlinearity, intrinsic stochasticity, a qualitatively different behavior from an ODE solution, and partial observability. The computational speed of the MSS approach for the Fisher information matrix allows for an application in realistic size models.

The performance of sample selection estimators to control for attrition bias.

PubMed

Grasdal, A

2001-07-01

Sample attrition is a potential source of selection bias in experimental, as well as non-experimental programme evaluation. For labour market outcomes, such as employment status and earnings, missing data problems caused by attrition can be circumvented by the collection of follow-up data from administrative registers. For most non-labour market outcomes, however, investigators must rely on participants' willingness to co-operate in keeping detailed follow-up records and statistical correction procedures to identify and adjust for attrition bias. This paper combines survey and register data from a Norwegian randomized field trial to evaluate the performance of parametric and semi-parametric sample selection estimators commonly used to correct for attrition bias. The considered estimators work well in terms of producing point estimates of treatment effects close to the experimental benchmark estimates. Results are sensitive to exclusion restrictions. The analysis also demonstrates an inherent paradox in the 'common support' approach, which prescribes exclusion from the analysis of observations outside of common support for the selection probability. The more important treatment status is as a determinant of attrition, the larger is the proportion of treated with support for the selection probability outside the range, for which comparison with untreated counterparts is possible. Copyright 2001 John Wiley & Sons, Ltd.

Online gas composition estimation in solid oxide fuel cell systems with anode off-gas recycle configuration

NASA Astrophysics Data System (ADS)

Dolenc, B.; Vrečko, D.; Juričić, Ð.; Pohjoranta, A.; Pianese, C.

2017-03-01

Degradation and poisoning of solid oxide fuel cell (SOFC) stacks are continuously shortening the lifespan of SOFC systems. Poisoning mechanisms, such as carbon deposition, form a coating layer, hence rapidly decreasing the efficiency of the fuel cells. Gas composition of inlet gases is known to have great impact on the rate of coke formation. Therefore, monitoring of these variables can be of great benefit for overall management of SOFCs. Although measuring the gas composition of the gas stream is feasible, it is too costly for commercial applications. This paper proposes three distinct approaches for the design of gas composition estimators of an SOFC system in anode off-gas recycle configuration which are (i.) accurate, and (ii.) easy to implement on a programmable logic controller. Firstly, a classical approach is briefly revisited and problems related to implementation complexity are discussed. Secondly, the model is simplified and adapted for easy implementation. Further, an alternative data-driven approach for gas composition estimation is developed. Finally, a hybrid estimator employing experimental data and 1st-principles is proposed. Despite the structural simplicity of the estimators, the experimental validation shows a high precision for all of the approaches. Experimental validation is performed on a 10 kW SOFC system.

Partitioning Tracer Test for Detection, Estimation, and Remediation Performance Assessment of Subsurface Nonaqueous Phase Liquids

NASA Astrophysics Data System (ADS)

Jin, Minquan; Delshad, Mojdeh; Dwarakanath, Varadarajan; McKinney, Daene C.; Pope, Gary A.; Sepehrnoori, Kamy; Tilburg, Charles E.; Jackson, Richard E.

1995-05-01

In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by nonaqueous phase liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypothetical two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations.

Partitioning tracer test for detection, estimation, and remediation performance assessment of subsurface nonaqueous phase liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, M.; Delshad, M.; Dwarakanath, V.

1995-05-01

In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by nonaqueous phase liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypotheticalmore » two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer test results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations. 43 refs., 10 figs., 1 tab.« less

The Implications of "Contamination" for Experimental Design in Education

ERIC Educational Resources Information Center

Rhoads, Christopher H.

2011-01-01

Experimental designs that randomly assign entire clusters of individuals (e.g., schools and classrooms) to treatments are frequently advocated as a way of guarding against contamination of the estimated average causal effect of treatment. However, in the absence of contamination, experimental designs that randomly assign intact clusters to…

Theoretical and experimental researches of the liquid evaporation during thermal vacuum influences

NASA Astrophysics Data System (ADS)

Trushlyakov, V.; Panichkin, A.; Prusova, O.; Zharikov, K.; Dron, M.

2018-01-01

The mathematical model of the evaporation process of model liquid with the free surface boundary conditions of the "mirror" type under thermal vacuum influence and the numerical estimates of the evaporation process parameters are developed. An experimental stand, comprising a vacuum chamber, an experimental model tank with a heating element is designed; the experimental data are obtained. A comparative analysis of numerical and experimental results showed their close match.

A continuous optimization approach for inferring parameters in mathematical models of regulatory networks.

PubMed

Deng, Zhimin; Tian, Tianhai

2014-07-29

The advances of systems biology have raised a large number of sophisticated mathematical models for describing the dynamic property of complex biological systems. One of the major steps in developing mathematical models is to estimate unknown parameters of the model based on experimentally measured quantities. However, experimental conditions limit the amount of data that is available for mathematical modelling. The number of unknown parameters in mathematical models may be larger than the number of observation data. The imbalance between the number of experimental data and number of unknown parameters makes reverse-engineering problems particularly challenging. To address the issue of inadequate experimental data, we propose a continuous optimization approach for making reliable inference of model parameters. This approach first uses a spline interpolation to generate continuous functions of system dynamics as well as the first and second order derivatives of continuous functions. The expanded dataset is the basis to infer unknown model parameters using various continuous optimization criteria, including the error of simulation only, error of both simulation and the first derivative, or error of simulation as well as the first and second derivatives. We use three case studies to demonstrate the accuracy and reliability of the proposed new approach. Compared with the corresponding discrete criteria using experimental data at the measurement time points only, numerical results of the ERK kinase activation module show that the continuous absolute-error criteria using both function and high order derivatives generate estimates with better accuracy. This result is also supported by the second and third case studies for the G1/S transition network and the MAP kinase pathway, respectively. This suggests that the continuous absolute-error criteria lead to more accurate estimates than the corresponding discrete criteria. We also study the robustness property of these three models to examine the reliability of estimates. Simulation results show that the models with estimated parameters using continuous fitness functions have better robustness properties than those using the corresponding discrete fitness functions. The inference studies and robustness analysis suggest that the proposed continuous optimization criteria are effective and robust for estimating unknown parameters in mathematical models.

Theoretical methods for estimating moments of inertia of trees and boles.

Treesearch

John A. Sturos

1973-01-01

Presents a theoretical method for estimating the mass moments of inertia of full trees and boles about a transverse axis. Estimates from the theoretical model compared closely with experimental data on aspen and red pine trees obtained in the field by the pendulum method. The theoretical method presented may be used to estimate the mass moments of inertia and other...

Residual Wage Differences by Gender: Bounding the Estimates.

ERIC Educational Resources Information Center

Sakellariou, Chris N.; Patrinos, Harry A.

1996-01-01

Uses data from the 1986 Canadian labor market activity survey file to derive estimates of residual gender wage gap differences. Investigates these estimates' dependence on experimental design and on assumptions about discrimination-free wage structures. Residual differences persist, even after restricting the sample to a group of highly motivated,…

Iowa flood studies (IFloodS) in the South Fork experimental watershed: soil moisture and precipitation monitoring

USDA-ARS?s Scientific Manuscript database

Soil moisture estimates are valuable for hydrologic modeling and agricultural decision support. These estimates are typically produced via a combination of sparse ¬in situ networks and remotely-sensed products or where sensory grids and quality satellite estimates are unavailable, through derived h...

Design of Low-Cost Vehicle Roll Angle Estimator Based on Kalman Filters and an Iot Architecture.

PubMed

Garcia Guzman, Javier; Prieto Gonzalez, Lisardo; Pajares Redondo, Jonatan; Sanz Sanchez, Susana; Boada, Beatriz L

2018-06-03

In recent years, there have been many advances in vehicle technologies based on the efficient use of real-time data provided by embedded sensors. Some of these technologies can help you avoid or reduce the severity of a crash such as the Roll Stability Control (RSC) systems for commercial vehicles. In RSC, several critical variables to consider such as sideslip or roll angle can only be directly measured using expensive equipment. These kind of devices would increase the price of commercial vehicles. Nevertheless, sideslip or roll angle or values can be estimated using MEMS sensors in combination with data fusion algorithms. The objectives stated for this research work consist of integrating roll angle estimators based on Linear and Unscented Kalman filters to evaluate the precision of the results obtained and determining the fulfillment of the hard real-time processing constraints to embed this kind of estimators in IoT architectures based on low-cost equipment able to be deployed in commercial vehicles. An experimental testbed composed of a van with two sets of low-cost kits was set up, the first one including a Raspberry Pi 3 Model B, and the other having an Intel Edison System on Chip. This experimental environment was tested under different conditions for comparison. The results obtained from low-cost experimental kits, based on IoT architectures and including estimators based on Kalman filters, provide accurate roll angle estimation. Also, these results show that the processing time to get the data and execute the estimations based on Kalman Filters fulfill hard real time constraints.

Sensitivity and systematics of calorimetric neutrino mass experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nucciotti, A.; Cremonesi, O.; Ferri, E.

2009-12-16

A large calorimetric neutrino mass experiment using thermal detectors is expected to play a crucial role in the challenge for directly assessing the neutrino mass. We discuss and compare here two approaches for the estimation of the experimental sensitivity of such an experiment. The first method uses an analytic formulation and allows to obtain readily a close estimate over a wide range of experimental configurations. The second method is based on a Montecarlo technique and is more precise and reliable. The Montecarlo approach is then exploited to study some sources of systematic uncertainties peculiar to calorimetric experiments. Finally, the toolsmore » are applied to investigate the optimal experimental configuration of the MARE project.« less

Estimation of squeeze-film damping and inertial coefficients from experimental free-decay data

NASA Technical Reports Server (NTRS)

Roberts, J. B.; of Mechanical Engineers, London.

1987-01-01

The results are given for an experimental program concerned with a parametric identification of the damping and inertial coefficients of a cylindrical squeeze-film bearing, through an analysis of transient response data. The results enable the operating range for which a linear model of the squeeze-film is appropriate to be determined. Comparisons are made between the estimated coefficients and theoretical predictions. Presentation is by courtesy of the Council of the Institution of Mechanical Engineers, London.

Experimental validation of pulsed column inventory estimators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beyerlein, A.L.; Geldard, J.F.; Weh, R.

Near-real-time accounting (NRTA) for reprocessing plants relies on the timely measurement of all transfers through the process area and all inventory in the process. It is difficult to measure the inventory of the solvent contractors; therefore, estimation techniques are considered. We have used experimental data obtained at the TEKO facility in Karlsruhe and have applied computer codes developed at Clemson University to analyze this data. For uranium extraction, the computer predictions agree to within 15% of the measured inventories. We believe this study is significant in demonstrating that using theoretical models with a minimum amount of process data may bemore » an acceptable approach to column inventory estimation for NRTA. 15 refs., 7 figs.« less

Stochastic estimation of human shoulder impedance with robots: an experimental design.

PubMed

Park, Kyungbin; Chang, Pyung Hun

2011-01-01

Previous studies assumed the shoulder as a hinge joint during human arm impedance measurement. This is obviously a vast simplification since the shoulder is a complex of several joints with multiple degrees of freedom. In the present work, a practical methodology for more general and realistic estimation of human shoulder impedance is proposed and validated with a spring array. It includes a gravity compensation scheme, which is developed and used for the experiments with a spatial three degrees of freedom PUMA-type robot. The experimental results were accurate and reliable, and thus it has shown a strong potential of the proposed methodology in the estimation of human shoulder impedance. © 2011 IEEE

Angular velocity estimation from measurement vectors of star tracker.

PubMed

Liu, Hai-bo; Yang, Jun-cai; Yi, Wen-jun; Wang, Jiong-qi; Yang, Jian-kun; Li, Xiu-jian; Tan, Ji-chun

2012-06-01

In most spacecraft, there is a need to know the craft's angular rate. Approaches with least squares and an adaptive Kalman filter are proposed for estimating the angular rate directly from the star tracker measurements. In these approaches, only knowledge of the vector measurements and sampling interval is required. The designed adaptive Kalman filter can filter out noise without information of the dynamic model and inertia dyadic. To verify the proposed estimation approaches, simulations based on the orbit data of the challenging minisatellite payload (CHAMP) satellite and experimental tests with night-sky observation are performed. Both the simulations and experimental testing results have demonstrated that the proposed approach performs well in terms of accuracy, robustness, and performance.

Frequency domain surface EMG sensor fusion for estimating finger forces.

PubMed

Potluri, Chandrasekhar; Kumar, Parmod; Anugolu, Madhavi; Urfer, Alex; Chiu, Steve; Naidu, D; Schoen, Marco P

2010-01-01

Extracting or estimating skeletal hand/finger forces using surface electro myographic (sEMG) signals poses many challenges due to cross-talk, noise, and a temporal and spatially modulated signal characteristics. Normal sEMG measurements are based on single sensor data. In this paper, array sensors are used along with a proposed sensor fusion scheme that result in a simple Multi-Input-Single-Output (MISO) transfer function. Experimental data is used along with system identification to find this MISO system. A Genetic Algorithm (GA) approach is employed to optimize the characteristics of the MISO system. The proposed fusion-based approach is tested experimentally and indicates improvement in finger/hand force estimation.

Drinking behaviour and water turnover rates of Antarctic fur seal pups: implications for the estimation of milk intake by isotopic dilution.

PubMed

Lea, Mary-Anne; Bonadonna, Francesco; Hindell, Mark A; Guinet, Christophe; Goldsworthy, Simon D

2002-06-01

The estimation of milk consumption in free-ranging seals using tritium dilution techniques makes the key assumption that the animals drink no pre-formed water during the experimental period. However, frequent observations of unweaned Antarctic fur seal pups drinking water at Iles Kerguelen necessitated the testing of this assumption. We estimated water flux rates of 30 pups (10.7+/-0.3 kg) in four experimental groups by isotopic dilution over 4 days. The groups were: (1) pups held in an open air enclosure without access to water to estimate fasting metabolic water production (MWP); (2) free-ranging pups not administered additional water; (3) pups held in an open air enclosure and given a total of 300 ml of fresh water to verify technique accuracy; and (4) free-ranging pups given 200 ml of fresh water. Pups without access to water exhibited water flux rates (20.5+/-0.8 ml kg(-1)d(-1)), which were significantly lower than those observed for the free-ranging group (33.0+/-1.7 ml kg(-1) d(-1)). Mean estimated pre-formed water intake for the free-ranging experimental groups was 12.6 ml kg(-1) d(-1). Thus, MWP, measured as total water intake during fasting, may be significantly over-estimated in free-ranging Antarctic fur seal pups at Iles Kerguelen and at other sites and subsequently milk intake rates may be underestimated.

Estimation of the water retention curve from the soil hydraulic conductivity and sorptivity in an upward infiltration process

NASA Astrophysics Data System (ADS)

Moret-Fernández, David; Angulo, Marta; Latorre, Borja; González-Cebollada, César; López, María Victoria

2017-04-01

Determination of the saturated hydraulic conductivity, Ks, and the α and n parameters of the van Genuchten (1980) water retention curve, θ(h), are fundamental to fully understand and predict soil water distribution. This work presents a new procedure to estimate the soil hydraulic properties from the inverse analysis of a single cumulative upward infiltration curve followed by an overpressure step at the end of the wetting process. Firstly, Ks is calculated by the Darcy's law from the overpressure step. The soil sorptivity (S) is then estimated using the Haverkamp et al., (1994) equation. Next, a relationship between α and n, f(α,n), is calculated from the estimated Sand Ks. The α and n values are finally obtained by the inverse analysis of the experimental data after applying the f(α,n) relationship to the HYDRUS-1D model. The method was validated on theoretical synthetic curves for three different soils (sand, loam and clay), and subsequently tested on experimental sieved soils (sand, loam, clay loam and clay) of known hydraulic properties. A robust relationship was observed between the theoretical α and nvalues (R2 > 0.99) of the different synthetic soils and those estimated from inverse analysis of the upward infiltration curve. Consistent results were also obtained for the experimental soils (R2 > 0.85). These results demonstrated that this technique allowed accurate estimates of the soil hydraulic properties for a wide range of textures, including clay soils.

Estimating Intervention Effects across Different Types of Single-Subject Experimental Designs: Empirical Illustration

ERIC Educational Resources Information Center

Moeyaert, Mariola; Ugille, Maaike; Ferron, John M.; Onghena, Patrick; Heyvaert, Mieke; Beretvas, S. Natasha; Van den Noortgate, Wim

2015-01-01

The purpose of this study is to illustrate the multilevel meta-analysis of results from single-subject experimental designs of different types, including AB phase designs, multiple-baseline designs, ABAB reversal designs, and alternating treatment designs. Current methodological work on the meta-analysis of single-subject experimental designs…

Simplified Estimation and Testing in Unbalanced Repeated Measures Designs.

PubMed

Spiess, Martin; Jordan, Pascal; Wendt, Mike

2018-05-07

In this paper we propose a simple estimator for unbalanced repeated measures design models where each unit is observed at least once in each cell of the experimental design. The estimator does not require a model of the error covariance structure. Thus, circularity of the error covariance matrix and estimation of correlation parameters and variances are not necessary. Together with a weak assumption about the reason for the varying number of observations, the proposed estimator and its variance estimator are unbiased. As an alternative to confidence intervals based on the normality assumption, a bias-corrected and accelerated bootstrap technique is considered. We also propose the naive percentile bootstrap for Wald-type tests where the standard Wald test may break down when the number of observations is small relative to the number of parameters to be estimated. In a simulation study we illustrate the properties of the estimator and the bootstrap techniques to calculate confidence intervals and conduct hypothesis tests in small and large samples under normality and non-normality of the errors. The results imply that the simple estimator is only slightly less efficient than an estimator that correctly assumes a block structure of the error correlation matrix, a special case of which is an equi-correlation matrix. Application of the estimator and the bootstrap technique is illustrated using data from a task switch experiment based on an experimental within design with 32 cells and 33 participants.

Device-independent point estimation from finite data and its application to device-independent property estimation

NASA Astrophysics Data System (ADS)

Lin, Pei-Sheng; Rosset, Denis; Zhang, Yanbao; Bancal, Jean-Daniel; Liang, Yeong-Cherng

2018-03-01

The device-independent approach to physics is one where conclusions are drawn directly from the observed correlations between measurement outcomes. In quantum information, this approach allows one to make strong statements about the properties of the underlying systems or devices solely via the observation of Bell-inequality-violating correlations. However, since one can only perform a finite number of experimental trials, statistical fluctuations necessarily accompany any estimation of these correlations. Consequently, an important gap remains between the many theoretical tools developed for the asymptotic scenario and the experimentally obtained raw data. In particular, a physical and concurrently practical way to estimate the underlying quantum distribution has so far remained elusive. Here, we show that the natural analogs of the maximum-likelihood estimation technique and the least-square-error estimation technique in the device-independent context result in point estimates of the true distribution that are physical, unique, computationally tractable, and consistent. They thus serve as sound algorithmic tools allowing one to bridge the aforementioned gap. As an application, we demonstrate how such estimates of the underlying quantum distribution can be used to provide, in certain cases, trustworthy estimates of the amount of entanglement present in the measured system. In stark contrast to existing approaches to device-independent parameter estimations, our estimation does not require the prior knowledge of any Bell inequality tailored for the specific property and the specific distribution of interest.

Measurements of experimental precision for trials with cowpea (Vigna unguiculata L. Walp.) genotypes.

PubMed

Teodoro, P E; Torres, F E; Santos, A D; Corrêa, A M; Nascimento, M; Barroso, L M A; Ceccon, G

2016-05-09

The aim of this study was to evaluate the suitability of statistics as experimental precision degree measures for trials with cowpea (Vigna unguiculata L. Walp.) genotypes. Cowpea genotype yields were evaluated in 29 trials conducted in Brazil between 2005 and 2012. The genotypes were evaluated with a randomized block design with four replications. Ten statistics that were estimated for each trial were compared using descriptive statistics, Pearson correlations, and path analysis. According to the class limits established, selective accuracy and F-test values for genotype, heritability, and the coefficient of determination adequately estimated the degree of experimental precision. Using these statistics, 86.21% of the trials had adequate experimental precision. Selective accuracy and the F-test values for genotype, heritability, and the coefficient of determination were directly related to each other, and were more suitable than the coefficient of variation and the least significant difference (by the Tukey test) to evaluate experimental precision in trials with cowpea genotypes.

Computational Fluid Dynamics Uncertainty Analysis Applied to Heat Transfer over a Flat Plate

NASA Technical Reports Server (NTRS)

Groves, Curtis Edward; Ilie, Marcel; Schallhorn, Paul A.

2013-01-01

There have been few discussions on using Computational Fluid Dynamics (CFD) without experimental validation. Pairing experimental data, uncertainty analysis, and analytical predictions provides a comprehensive approach to verification and is the current state of the art. With pressed budgets, collecting experimental data is rare or non-existent. This paper investigates and proposes a method to perform CFD uncertainty analysis only from computational data. The method uses current CFD uncertainty techniques coupled with the Student-T distribution to predict the heat transfer coefficient over a at plate. The inputs to the CFD model are varied from a specified tolerance or bias error and the difference in the results are used to estimate the uncertainty. The variation in each input is ranked from least to greatest to determine the order of importance. The results are compared to heat transfer correlations and conclusions drawn about the feasibility of using CFD without experimental data. The results provide a tactic to analytically estimate the uncertainty in a CFD model when experimental data is unavailable

The influence of the design matrix on treatment effect estimates in the quantitative analyses of single-subject experimental design research.

PubMed

Moeyaert, Mariola; Ugille, Maaike; Ferron, John M; Beretvas, S Natasha; Van den Noortgate, Wim

2014-09-01

The quantitative methods for analyzing single-subject experimental data have expanded during the last decade, including the use of regression models to statistically analyze the data, but still a lot of questions remain. One question is how to specify predictors in a regression model to account for the specifics of the design and estimate the effect size of interest. These quantitative effect sizes are used in retrospective analyses and allow synthesis of single-subject experimental study results which is informative for evidence-based decision making, research and theory building, and policy discussions. We discuss different design matrices that can be used for the most common single-subject experimental designs (SSEDs), namely, the multiple-baseline designs, reversal designs, and alternating treatment designs, and provide empirical illustrations. The purpose of this article is to guide single-subject experimental data analysts interested in analyzing and meta-analyzing SSED data. © The Author(s) 2014.

A Robust Adaptive Autonomous Approach to Optimal Experimental Design

NASA Astrophysics Data System (ADS)

Gu, Hairong

Experimentation is the fundamental tool of scientific inquiries to understand the laws governing the nature and human behaviors. Many complex real-world experimental scenarios, particularly in quest of prediction accuracy, often encounter difficulties to conduct experiments using an existing experimental procedure for the following two reasons. First, the existing experimental procedures require a parametric model to serve as the proxy of the latent data structure or data-generating mechanism at the beginning of an experiment. However, for those experimental scenarios of concern, a sound model is often unavailable before an experiment. Second, those experimental scenarios usually contain a large number of design variables, which potentially leads to a lengthy and costly data collection cycle. Incompetently, the existing experimental procedures are unable to optimize large-scale experiments so as to minimize the experimental length and cost. Facing the two challenges in those experimental scenarios, the aim of the present study is to develop a new experimental procedure that allows an experiment to be conducted without the assumption of a parametric model while still achieving satisfactory prediction, and performs optimization of experimental designs to improve the efficiency of an experiment. The new experimental procedure developed in the present study is named robust adaptive autonomous system (RAAS). RAAS is a procedure for sequential experiments composed of multiple experimental trials, which performs function estimation, variable selection, reverse prediction and design optimization on each trial. Directly addressing the challenges in those experimental scenarios of concern, function estimation and variable selection are performed by data-driven modeling methods to generate a predictive model from data collected during the course of an experiment, thus exempting the requirement of a parametric model at the beginning of an experiment; design optimization is performed to select experimental designs on the fly of an experiment based on their usefulness so that fewest designs are needed to reach useful inferential conclusions. Technically, function estimation is realized by Bayesian P-splines, variable selection is realized by Bayesian spike-and-slab prior, reverse prediction is realized by grid-search and design optimization is realized by the concepts of active learning. The present study demonstrated that RAAS achieves statistical robustness by making accurate predictions without the assumption of a parametric model serving as the proxy of latent data structure while the existing procedures can draw poor statistical inferences if a misspecified model is assumed; RAAS also achieves inferential efficiency by taking fewer designs to acquire useful statistical inferences than non-optimal procedures. Thus, RAAS is expected to be a principled solution to real-world experimental scenarios pursuing robust prediction and efficient experimentation.

Volumetric blood flow via time-domain correlation: experimental verification.

PubMed

Embree, P M; O'Brien, W R

1990-01-01

A novel ultrasonic volumetric flow measurement method using time-domain correlation of consecutive pairs of echoes has been developed. An ultrasonic data acquisition system determined the time shift between a pair of range gated echoes by searching for the time shift with the maximum correlation between the RF sampled waveforms. Experiments with a 5-MHz transducer indicate that the standard deviation of the estimate of steady fluid velocity through 6-mm-diameter tubes is less than 10% of the mean. Experimentally, Sephadex (G-50; 20-80 mum dia.) particles in water and fresh porcine blood have been used as ultrasound scattering fluids. Two-dimensional (2-D) flow velocity can be estimated by slowly sweeping the ultrasonic beam across the blood vessel phantom. Volumetric flow through the vessel is estimated by integrating the 2-D flow velocity field and then is compared to hydrodynamic flow measurements to assess the overall experimental accuracy of the time-domain method. Flow rates from 50-500 ml/min have been estimated with an accuracy better than 10% under the idealized characteristics used in this study, which include straight circular thin-walled tubes, laminar axially-symmetric steady flow, and no intervening tissues.

Plant Uptake of Organic Pollutants from Soil: A Critical Review ofBioconcentration Estimates Based on Modelsand Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKone, Thomas E.; Maddalena, Randy L.

2007-01-01

The role of terrestrial vegetation in transferring chemicals from soil and air into specific plant tissues (stems, leaves, roots, etc.) is still not well characterized. We provide here a critical review of plant-to-soil bioconcentration ratio (BCR) estimates based on models and experimental data. This review includes the conceptual and theoretical formulations of the bioconcentration ratio, constructing and calibrating empirical and mathematical algorithms to describe this ratio and the experimental data used to quantify BCRs and calibrate the model performance. We first evaluate the theoretical basis for the BCR concept and BCR models and consider how lack of knowledge and datamore » limits reliability and consistency of BCR estimates. We next consider alternate modeling strategies for BCR. A key focus of this evaluation is the relative contributions to overall uncertainty from model uncertainty versus variability in the experimental data used to develop and test the models. As a case study, we consider a single chemical, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and focus on variability of bioconcentration measurements obtained from 81 experiments with different plant species, different plant tissues, different experimental conditions, and different methods for reporting concentrations in the soil and plant tissues. We use these observations to evaluate both the magnitude of experimental variability in plant bioconcentration and compare this to model uncertainty. Among these 81 measurements, the variation of the plant/soil BCR has a geometric standard deviation (GSD) of 3.5 and a coefficient of variability (CV-ratio of arithmetic standard deviation to mean) of 1.7. These variations are significant but low relative to model uncertainties--which have an estimated GSD of 10 with a corresponding CV of 14.« less

Experimental Design for Stochastic Models of Nonlinear Signaling Pathways Using an Interval-Wise Linear Noise Approximation and State Estimation

PubMed Central

Zimmer, Christoph

2016-01-01

Background Computational modeling is a key technique for analyzing models in systems biology. There are well established methods for the estimation of the kinetic parameters in models of ordinary differential equations (ODE). Experimental design techniques aim at devising experiments that maximize the information encoded in the data. For ODE models there are well established approaches for experimental design and even software tools. However, data from single cell experiments on signaling pathways in systems biology often shows intrinsic stochastic effects prompting the development of specialized methods. While simulation methods have been developed for decades and parameter estimation has been targeted for the last years, only very few articles focus on experimental design for stochastic models. Methods The Fisher information matrix is the central measure for experimental design as it evaluates the information an experiment provides for parameter estimation. This article suggest an approach to calculate a Fisher information matrix for models containing intrinsic stochasticity and high nonlinearity. The approach makes use of a recently suggested multiple shooting for stochastic systems (MSS) objective function. The Fisher information matrix is calculated by evaluating pseudo data with the MSS technique. Results The performance of the approach is evaluated with simulation studies on an Immigration-Death, a Lotka-Volterra, and a Calcium oscillation model. The Calcium oscillation model is a particularly appropriate case study as it contains the challenges inherent to signaling pathways: high nonlinearity, intrinsic stochasticity, a qualitatively different behavior from an ODE solution, and partial observability. The computational speed of the MSS approach for the Fisher information matrix allows for an application in realistic size models. PMID:27583802

Soil moisture and precipitation monitoring in the South Fork experimental watershed during the Iowa flood studies (IFloodS)

USDA-ARS?s Scientific Manuscript database

Soil moisture estimates are valuable for hydrologic modeling and agricultural decision support. These estimates are typically produced via a combination of sparse in situ networks and remotely-sensed products or where sensory grids and quality satellite estimates are unavailable, through derived hy...

Are Structural Estimates of Auction Models Reasonable? Evidence from Experimental Data

ERIC Educational Resources Information Center

Bajari, Patrick; Hortacsu, Ali

2005-01-01

Recently, economists have developed methods for structural estimation of auction models. Many researchers object to these methods because they find the strict rationality assumptions to be implausible. Using bid data from first-price auction experiments, we estimate four alternative structural models: (1) risk-neutral Bayes-Nash, (2) risk-averse…

A method for the estimate of the wall diffusion for non-axisymmetric fields using rotating external fields

NASA Astrophysics Data System (ADS)

Frassinetti, L.; Olofsson, K. E. J.; Fridström, R.; Setiadi, A. C.; Brunsell, P. R.; Volpe, F. A.; Drake, J.

2013-08-01

A new method for the estimate of the wall diffusion time of non-axisymmetric fields is developed. The method based on rotating external fields and on the measurement of the wall frequency response is developed and tested in EXTRAP T2R. The method allows the experimental estimate of the wall diffusion time for each Fourier harmonic and the estimate of the wall diffusion toroidal asymmetries. The method intrinsically considers the effects of three-dimensional structures and of the shell gaps. Far from the gaps, experimental results are in good agreement with the diffusion time estimated with a simple cylindrical model that assumes a homogeneous wall. The method is also applied with non-standard configurations of the coil array, in order to mimic tokamak-relevant settings with a partial wall coverage and active coils of large toroidal extent. The comparison with the full coverage results shows good agreement if the effects of the relevant sidebands are considered.

Identification of modal parameters including unmeasured forces and transient effects

NASA Astrophysics Data System (ADS)

Cauberghe, B.; Guillaume, P.; Verboven, P.; Parloo, E.

2003-08-01

In this paper, a frequency-domain method to estimate modal parameters from short data records with known input (measured) forces and unknown input forces is presented. The method can be used for an experimental modal analysis, an operational modal analysis (output-only data) and the combination of both. A traditional experimental and operational modal analysis in the frequency domain starts respectively, from frequency response functions and spectral density functions. To estimate these functions accurately sufficient data have to be available. The technique developed in this paper estimates the modal parameters directly from the Fourier spectra of the outputs and the known input. Instead of using Hanning windows on these short data records the transient effects are estimated simultaneously with the modal parameters. The method is illustrated, tested and validated by Monte Carlo simulations and experiments. The presented method to process short data sequences leads to unbiased estimates with a small variance in comparison to the more traditional approaches.

Estimation of medium effects on equilibrium constants in moderate and high ionic strength solutions at elevated temperatures by using specific interaction theory (SIT): Interaction coefficients involving Cl, OH- and Ac- up to 200°C and 400 bars

PubMed Central

Xiong, Yongliang

2006-01-01

In this study, a series of interaction coefficients of the Brønsted-Guggenheim-Scatchard specific interaction theory (SIT) have been estimated up to 200°C and 400 bars. The interaction coefficients involving Cl- estimated include ε(H+, Cl-), ε(Na+, Cl-), ε(Ag+, Cl-), ε(Na+, AgCl2 -), ε(Mg2+, Cl-), ε(Ca2+, Cl-), ε(Sr2+, Cl-), ε(Ba2+, Cl-), ε(Sm3+, Cl-), ε(Eu3+, Cl-), ε(Gd3+, Cl-), and ε(GdAc2+, Cl-). The interaction coefficients involving OH- estimated include ε(Li+, OH-), ε(K+, OH-), ε(Na+, OH-), ε(Cs+, OH-), ε(Sr2+, OH-), and ε(Ba2+, OH-). In addition, the interaction coefficients of ε(Na+, Ac-) and ε(Ca2+, Ac-) have also been estimated. The bulk of interaction coefficients presented in this study has been evaluated from the mean activity coefficients. A few of them have been estimated from the potentiometric and solubility studies. The above interaction coefficients are tested against both experimental mean activity coefficients and equilibrium quotients. Predicted mean activity coefficients are in satisfactory agreement with experimental data. Predicted equilibrium quotients are in very good agreement with experimental values. Based upon its relatively rapid attainment of equilibrium and the ease of determining magnesium concentrations, this study also proposes that the solubility of brucite can be used as a pH (pcH) buffer/sensor for experimental systems in NaCl solutions up to 200°C by employing the predicted solubility quotients of brucite in conjunction with the dissociation quotients of water and the first hydrolysis quotients of Mg2+, all in NaCl solutions. PMID:16759370

Impact and quantification of the sources of error in DNA pooling designs.

PubMed

Jawaid, A; Sham, P

2009-01-01

The analysis of genome wide variation offers the possibility of unravelling the genes involved in the pathogenesis of disease. Genome wide association studies are also particularly useful for identifying and validating targets for therapeutic intervention as well as for detecting markers for drug efficacy and side effects. The cost of such large-scale genetic association studies may be reduced substantially by the analysis of pooled DNA from multiple individuals. However, experimental errors inherent in pooling studies lead to a potential increase in the false positive rate and a loss in power compared to individual genotyping. Here we quantify various sources of experimental error using empirical data from typical pooling experiments and corresponding individual genotyping counts using two statistical methods. We provide analytical formulas for calculating these different errors in the absence of complete information, such as replicate pool formation, and for adjusting for the errors in the statistical analysis. We demonstrate that DNA pooling has the potential of estimating allele frequencies accurately, and adjusting the pooled allele frequency estimates for differential allelic amplification considerably improves accuracy. Estimates of the components of error show that differential allelic amplification is the most important contributor to the error variance in absolute allele frequency estimation, followed by allele frequency measurement and pool formation errors. Our results emphasise the importance of minimising experimental errors and obtaining correct error estimates in genetic association studies.

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

NASA Astrophysics Data System (ADS)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

Sample size considerations for paired experimental design with incomplete observations of continuous outcomes.

PubMed

Zhu, Hong; Xu, Xiaohan; Ahn, Chul

2017-01-01

Paired experimental design is widely used in clinical and health behavioral studies, where each study unit contributes a pair of observations. Investigators often encounter incomplete observations of paired outcomes in the data collected. Some study units contribute complete pairs of observations, while the others contribute either pre- or post-intervention observations. Statistical inference for paired experimental design with incomplete observations of continuous outcomes has been extensively studied in literature. However, sample size method for such study design is sparsely available. We derive a closed-form sample size formula based on the generalized estimating equation approach by treating the incomplete observations as missing data in a linear model. The proposed method properly accounts for the impact of mixed structure of observed data: a combination of paired and unpaired outcomes. The sample size formula is flexible to accommodate different missing patterns, magnitude of missingness, and correlation parameter values. We demonstrate that under complete observations, the proposed generalized estimating equation sample size estimate is the same as that based on the paired t-test. In the presence of missing data, the proposed method would lead to a more accurate sample size estimate comparing with the crude adjustment. Simulation studies are conducted to evaluate the finite-sample performance of the generalized estimating equation sample size formula. A real application example is presented for illustration.

Development of an Agent-Based Model (ABM) to Simulate the Immune System and Integration of a Regression Method to Estimate the Key ABM Parameters by Fitting the Experimental Data

PubMed Central

Tong, Xuming; Chen, Jinghang; Miao, Hongyu; Li, Tingting; Zhang, Le

2015-01-01

Agent-based models (ABM) and differential equations (DE) are two commonly used methods for immune system simulation. However, it is difficult for ABM to estimate key parameters of the model by incorporating experimental data, whereas the differential equation model is incapable of describing the complicated immune system in detail. To overcome these problems, we developed an integrated ABM regression model (IABMR). It can combine the advantages of ABM and DE by employing ABM to mimic the multi-scale immune system with various phenotypes and types of cells as well as using the input and output of ABM to build up the Loess regression for key parameter estimation. Next, we employed the greedy algorithm to estimate the key parameters of the ABM with respect to the same experimental data set and used ABM to describe a 3D immune system similar to previous studies that employed the DE model. These results indicate that IABMR not only has the potential to simulate the immune system at various scales, phenotypes and cell types, but can also accurately infer the key parameters like DE model. Therefore, this study innovatively developed a complex system development mechanism that could simulate the complicated immune system in detail like ABM and validate the reliability and efficiency of model like DE by fitting the experimental data. PMID:26535589

Maximum likelihood estimation of protein kinetic parameters under weak assumptions from unfolding force spectroscopy experiments

NASA Astrophysics Data System (ADS)

Aioanei, Daniel; Samorì, Bruno; Brucale, Marco

2009-12-01

Single molecule force spectroscopy (SMFS) is extensively used to characterize the mechanical unfolding behavior of individual protein domains under applied force by pulling chimeric polyproteins consisting of identical tandem repeats. Constant velocity unfolding SMFS data can be employed to reconstruct the protein unfolding energy landscape and kinetics. The methods applied so far require the specification of a single stretching force increase function, either theoretically derived or experimentally inferred, which must then be assumed to accurately describe the entirety of the experimental data. The very existence of a suitable optimal force model, even in the context of a single experimental data set, is still questioned. Herein, we propose a maximum likelihood (ML) framework for the estimation of protein kinetic parameters which can accommodate all the established theoretical force increase models. Our framework does not presuppose the existence of a single force characteristic function. Rather, it can be used with a heterogeneous set of functions, each describing the protein behavior in the stretching time range leading to one rupture event. We propose a simple way of constructing such a set of functions via piecewise linear approximation of the SMFS force vs time data and we prove the suitability of the approach both with synthetic data and experimentally. Additionally, when the spontaneous unfolding rate is the only unknown parameter, we find a correction factor that eliminates the bias of the ML estimator while also reducing its variance. Finally, we investigate which of several time-constrained experiment designs leads to better estimators.

Experimental and theoretical characterization of an AC electroosmotic micromixer.

PubMed

Sasaki, Naoki; Kitamori, Takehiko; Kim, Haeng-Boo

2010-01-01

We have reported on a novel microfluidic mixer based on AC electroosmosis. To elucidate the mixer characteristics, we performed detailed measurements of mixing under various experimental conditions including applied voltage, frequency and solution viscosity. The results are discussed through comparison with results obtained from a theoretical model of AC electroosmosis. As predicted from the theoretical model, we found that a larger voltage (approximately 20 V(p-p)) led to more rapid mixing, while the dependence of the mixing on frequency (1-5 kHz) was insignificant under the present experimental conditions. Furthermore, the dependence of the mixing on viscosity was successfully explained by the theoretical model, and the applicability of the mixer in viscous solution (2.83 mPa s) was confirmed experimentally. By using these results, it is possible to estimate the mixing performance under given conditions. These estimations can provide guidelines for using the mixer in microfluidic chemical analysis.

Estimation of Soil-Water Characteristic Curves in Multiple-Cycles Using Membrane and TDR System

PubMed Central

Hong, Won-Taek; Jung, Young-Seok; Kang, Seonghun; Lee, Jong-Sub

2016-01-01

The objective of this study is to estimate multiple-cycles of the soil-water characteristic curve (SWCC) using an innovative volumetric pressure plate extractor (VPPE), which is incorporated with a membrane and time domain reflectometry (TDR). The pressure cell includes the membrane to reduce the experimental time and the TDR probe to automatically estimate the volumetric water content. For the estimation of SWCC using the VPPE system, four specimens with different grain size and void ratio are prepared. The volumetric water contents of the specimens according to the matric suction are measured by the burette system and are estimated in the TDR system during five cycles of SWCC tests. The volumetric water contents estimated by the TDR system are almost identical to those determined by the burette system. The experimental time significantly decreases with the new VPPE. The hysteresis in the SWCC is largest in the first cycle and is nearly identical after 1.5 cycles. As the initial void ratio decreases, the air entry value increases. This study suggests that the new VPPE may effectively estimate multiple-cycles of the SWCC of unsaturated soils. PMID:28774139

Sound wood residue left after experimental cuttings in old-growth redwood

Treesearch

Kenneth N. Boe

1967-01-01

An estimate was made of the sound wood logging residue remaining after three different experimental cuttings on the Redwood Experimental Forest, north coastal California. The statistics on volume, size, and soundness classes are indicators of what to expect where similar volumes are harvested. The information can be useful to those planning use of logging residues,...

Efficacy and safety of remifentanil for analgesia in cesarean delivery

PubMed Central

Zhou, Xuan; Jin, Lian-jin; Hu, Chun-yang; Chen, Meng; Li, Ying; Zhang, Yue-shun

2017-01-01

Abstract Background: This study aimed to assess the efficacy and safety of remifentanil as a general anesthetic during cesarean delivery. Material and Methods: Fifty women with singleton pregnancies undergoing cesarean delivery were randomly divided into intervention and control groups, each group containing 25 subjects. Participants in the intervention group received remifentanil (infused at 2 μg/kg/h), whereas subjects in the control group were given dexmedetomidine (infused at 0.4 μg/kg/h). Outcome measurements included mean arterial blood pressure (MAP), heart rate (HR), bispectral index (BIS), Apgar scores at 1 and 5 minutes, and the pH, PCO2, PO2, and base excess (BE) of umbilical venous and arterial blood. Results: Forty-four participants completed the study. Patients in the intervention group did not experience greater effect and safety than those in the control group (P > .05), although MAP and BIS values decreased significantly immediately before laryngoscopy (P < .05). In addition, BIS values were reduced significantly at the time of skin incision, at uterine incision, and immediately after fetal delivery when compared with baseline values in both groups (P < .01). Conclusion: This study concluded that remifentanil and dexmedetomidine exhibited similar efficacy and safety during general anesthesia for cesarean delivery. PMID:29310326

Wireless modification of the intraoperative examination monitor for awake surgery.

PubMed

Yoshimitsu, Kitaro; Maruyama, Takashi; Muragaki, Yoshihiro; Suzuki, Takashi; Saito, Taiichi; Nitta, Masayuki; Tanaka, Masahiko; Chernov, Mikhail; Tamura, Manabu; Ikuta, Soko; Okamoto, Jun; Okada, Yoshikazu; Iseki, Hiroshi

2011-01-01

The dedicated intraoperative examination monitor for awake surgery (IEMAS) was originally developed by us to facilitate the process of brain mapping during awake craniotomy and successfully used in 186 neurosurgical procedures. This information-sharing device provides the opportunity for all members of the surgical team to visualize a wide spectrum of the integrated intraoperative information related to the condition of the patient, nuances of the surgical procedure, and details of the cortical mapping, practically without interruption of the surgical manipulations. The wide set of both anatomical and functional parameters, such as view of the patient's mimic and face movements while answering the specific questions, type of the examination test, position of the surgical instruments, parameters of the bispectral index monitor, and general view of the surgical field through the operating microscope, is presented compactly in one screen with several displays. However, the initially designed IEMAS system was occasionally affected by interruption or detachment of the connecting cables, which sometimes interfered with its effective clinical use. Therefore, a new modification of the device was developed. The specific feature is installation of wireless information transmitting technology using audio-visual transmitters and receivers for transfer of images and verbal information. The modified IEMAS system is very convenient to use in the narrow space of the operating room.

Asymmetry of wind waves studied in a laboratory tank

NASA Astrophysics Data System (ADS)

Ileykin, L. A.; Donelan, M. A.; Mellen, R. H.; McLaughlin, D. J.

1995-03-01

Asymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves) varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves). At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976). The phase shift between o). harmonics is found and shown to increase with the asymmetry of the waves.

Asymmetry of wind waves studied in a laboratory tank

NASA Astrophysics Data System (ADS)

Leykin, I. A.; Donelan, M. A.; Mellen, R. H.; McLaughlin, D. J.

Asymmetry of wind waves was studied in laboratory tank tinder varied wind and fetch conditions using both bispectral analysis of wave records and third-order statistics of the surface elevation. It is found skewness S (the normalized third-order moment of surface elevation describing the horizontal asymmetry waves) varies only slightly with the inverse wave u*/Cm (where u* is the air friction velocity and Cm is phase speed of the dominant waves). At the same time asymmetry A, which is determined from the Hilbert transform of the wave record and characterizes the skewness of the rate of change of surface elevation, increase consistently in magnitude with the ratio u*/Cm. This suggests that nonlinear distortion of the wave profile determined by the degree of wind forcing and is a sensitive indicator of wind-wave interaction processes. It is shown that the asymmetric profile of waves can described within the frameworks of the nonlinear nonspectral concept (Plate, 1972; Lake and Yuen, 197 according to which the wind-wave field can be represented as a coherent bound-wave system consisting mainly of dominant component w. and its harmonics propagating with the same speed C. , as observed by Ramamonjiaris and Coantic (1976). The phase shift between o). harmonics is found and shown to increase with the asymmetry of the waves.

Computational Depth of Anesthesia via Multiple Vital Signs Based on Artificial Neural Networks.

PubMed

Sadrawi, Muammar; Fan, Shou-Zen; Abbod, Maysam F; Jen, Kuo-Kuang; Shieh, Jiann-Shing

2015-01-01

This study evaluated the depth of anesthesia (DoA) index using artificial neural networks (ANN) which is performed as the modeling technique. Totally 63-patient data is addressed, for both modeling and testing of 17 and 46 patients, respectively. The empirical mode decomposition (EMD) is utilized to purify between the electroencephalography (EEG) signal and the noise. The filtered EEG signal is subsequently extracted to achieve a sample entropy index by every 5-second signal. Then, it is combined with other mean values of vital signs, that is, electromyography (EMG), heart rate (HR), pulse, systolic blood pressure (SBP), diastolic blood pressure (DBP), and signal quality index (SQI) to evaluate the DoA index as the input. The 5 doctor scores are averaged to obtain an output index. The mean absolute error (MAE) is utilized as the performance evaluation. 10-fold cross-validation is performed in order to generalize the model. The ANN model is compared with the bispectral index (BIS). The results show that the ANN is able to produce lower MAE than BIS. For the correlation coefficient, ANN also has higher value than BIS tested on the 46-patient testing data. Sensitivity analysis and cross-validation method are applied in advance. The results state that EMG has the most effecting parameter, significantly.

Computational Depth of Anesthesia via Multiple Vital Signs Based on Artificial Neural Networks

PubMed Central

Sadrawi, Muammar; Fan, Shou-Zen; Abbod, Maysam F.; Jen, Kuo-Kuang; Shieh, Jiann-Shing

2015-01-01

This study evaluated the depth of anesthesia (DoA) index using artificial neural networks (ANN) which is performed as the modeling technique. Totally 63-patient data is addressed, for both modeling and testing of 17 and 46 patients, respectively. The empirical mode decomposition (EMD) is utilized to purify between the electroencephalography (EEG) signal and the noise. The filtered EEG signal is subsequently extracted to achieve a sample entropy index by every 5-second signal. Then, it is combined with other mean values of vital signs, that is, electromyography (EMG), heart rate (HR), pulse, systolic blood pressure (SBP), diastolic blood pressure (DBP), and signal quality index (SQI) to evaluate the DoA index as the input. The 5 doctor scores are averaged to obtain an output index. The mean absolute error (MAE) is utilized as the performance evaluation. 10-fold cross-validation is performed in order to generalize the model. The ANN model is compared with the bispectral index (BIS). The results show that the ANN is able to produce lower MAE than BIS. For the correlation coefficient, ANN also has higher value than BIS tested on the 46-patient testing data. Sensitivity analysis and cross-validation method are applied in advance. The results state that EMG has the most effecting parameter, significantly. PMID:26568957

Sample Entropy Analysis of EEG Signals via Artificial Neural Networks to Model Patients' Consciousness Level Based on Anesthesiologists Experience

PubMed Central

Jiang, George J. A.; Fan, Shou-Zen; Abbod, Maysam F.; Huang, Hui-Hsun; Lan, Jheng-Yan; Tsai, Feng-Fang; Chang, Hung-Chi; Yang, Yea-Wen; Chuang, Fu-Lan; Chiu, Yi-Fang; Jen, Kuo-Kuang; Wu, Jeng-Fu; Shieh, Jiann-Shing

2015-01-01

Electroencephalogram (EEG) signals, as it can express the human brain's activities and reflect awareness, have been widely used in many research and medical equipment to build a noninvasive monitoring index to the depth of anesthesia (DOA). Bispectral (BIS) index monitor is one of the famous and important indicators for anesthesiologists primarily using EEG signals when assessing the DOA. In this study, an attempt is made to build a new indicator using EEG signals to provide a more valuable reference to the DOA for clinical researchers. The EEG signals are collected from patients under anesthetic surgery which are filtered using multivariate empirical mode decomposition (MEMD) method and analyzed using sample entropy (SampEn) analysis. The calculated signals from SampEn are utilized to train an artificial neural network (ANN) model through using expert assessment of consciousness level (EACL) which is assessed by experienced anesthesiologists as the target to train, validate, and test the ANN. The results that are achieved using the proposed system are compared to BIS index. The proposed system results show that it is not only having similar characteristic to BIS index but also more close to experienced anesthesiologists which illustrates the consciousness level and reflects the DOA successfully. PMID:25738152

Coexistence of gamma and high-frequency oscillations in rat medial entorhinal cortex in vitro

PubMed Central

Cunningham, M O; Halliday, David M; Davies, Ceri H; Traub, Roger D; Buhl, Eberhard H; Whittington, Miles A

2004-01-01

High frequency oscillations (> 80–90 Hz) occur in neocortex and hippocampus in vivo where they are associated with specific behavioural states and more classical EEG frequency bands. In the hippocampus in vitro these oscillations can occur in the absence of pyramidal neuronal somatodendritic compartments and are temporally correlated with on-going, persistent gamma frequency oscillations. Their occurrence in the hippocampus is dependent on gap-junctional communication and it has been suggested that these high frequency oscillations originate as collective behaviour in populations of electrically coupled principal cell axonal compartments. Here we demonstrate that the superficial layers of medial entorhinal cortex can also generate high frequency oscillations associated with gamma rhythms. During persistent gamma frequency oscillations high frequency oscillations occur with a high bispectral coherence with the field gamma activity. Bursts of high frequency oscillations are temporally correlated with both the onset of compound excitatory postsynaptic potentials in fast-spiking interneurones and spikelet potentials in both pyramidal and stellate principal neurones. Both the gamma frequency and high frequency oscillations were attenuated by the gap junction blocker carbenoxolone. These data suggest that high frequency oscillations may represent the substrate for phasic drive to interneurones during persistent gamma oscillations in the medial entorhinal cortex. PMID:15254156

Cloud-property retrieval using merged HIRS and AVHRR data

NASA Technical Reports Server (NTRS)

Baum, Bryan A.; Wielicki, Bruce A.; Minnis, Patrick; Parker, Lindsay

1992-01-01

A technique is developed that uses a multispectral, multiresolution method to improve the overall retrieval of mid- to high-level cloud properties by combining HIRS sounding channel data with higher spatial resolution AVHRR radiometric data collocated with the HIRS footprint. Cirrus cloud radiative and physical properties are determined using satellite data, surface-based measurements provided by rawinsondes and lidar, and aircraft-based lidar data collected during the First International Satellite Cloud Climatology Program Regional Experiment in Wisconsin during the months of October and November 1986. HIRS cloud-height retrievals are compared to ground-based lidar and aircraft lidar when possible. Retrieved cloud heights are found to have close agreement with lidar for thin cloud, but are higher than lidar for optically thick cloud. The results of the reflectance-emittance relationships derived are compared to theoretical scattering model results for both water-droplet spheres and randomly oriented hexagonal ice crystals. It is found that the assumption of 10-micron water droplets is inadequate to describe the reflectance-emittance relationship for the ice clouds seen here. Use of this assumption would lead to lower cloud heights using the ISCCP approach. The theoretical results show that use of hexagonal ice crystal phase functions could lead to much improved results for cloud retrieval algorithms using a bispectral approach.

Comparison of recovery parameters for xenon versus other inhalation anesthetics: systematic review and meta-analysis.

PubMed

Hou, Bingzong; Li, Fujing; Ou, Shanshan; Yang, Lukun; Zhou, Shaopeng

2016-03-01

To summarize and evaluate the available data describing the recovery parameters of xenon anesthesia. Systematic review and meta-analysis. Anesthesia for elective surgeries. Systematic review of randomized controlled trials (RCTs) from databases including Medline (1964-2013), the Cochrane Central Register of Controlled Trials (CENTRAL, 1990-2012), and Google Scholar (1966-2013). Inhalation of xenon or other anesthetics was administered in elective surgery. Recovery parameters (time to recovery, alertness/sedation scale scores at "eye opening," bispectral index at "reaction on demand," time to extubation, and time to orientation). Eleven RCTs (N = 661 patients) met the inclusion criteria. Recovery from xenon anesthesia was significantly faster in terms of the time to eye opening (mean difference [MD], -4.18 minutes; 95% confidence interval [CI], -5.03 to -3.32 minutes; P < .00001), the time to reaction on demand (MD, -5.35 minutes; 95% CI, -6.59 to -4.11 minutes; P < .00001), the time to extubation (MD, -4.49 minutes; 95% CI, -5.40 to -3.58 minutes; P < .00001), and the time to orientation (MD, -4.99 minutes; 95% CI, -6.45 to -3.52 minutes; P < .00001). This meta-analysis confirmed that recovery from xenon anesthesia is faster than other inhalation anesthesia. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A wavelet transform based method to determine depth of anesthesia to prevent awareness during general anesthesia.

PubMed

Mousavi, Seyed Mortaza; Adamoğlu, Ahmet; Demiralp, Tamer; Shayesteh, Mahrokh G

2014-01-01

Awareness during general anesthesia for its serious psychological effects on patients and some juristically problems for anesthetists has been an important challenge during past decades. Monitoring depth of anesthesia is a fundamental solution to this problem. The induction of anesthesia alters frequency and mean of amplitudes of the electroencephalogram (EEG), and its phase couplings. We analyzed EEG changes for phase coupling between delta and alpha subbands using a new algorithm for depth of general anesthesia measurement based on complex wavelet transform (CWT) in patients anesthetized by Propofol. Entropy and histogram of modulated signals were calculated by taking bispectral index (BIS) values as reference. Entropies corresponding to different BIS intervals using Mann-Whitney U test showed that they had different continuous distributions. The results demonstrated that there is a phase coupling between 3 and 4 Hz in delta and 8-9 Hz in alpha subbands and these changes are shown better at the channel T 7 of EEG. Moreover, when BIS values increase, the entropy value of modulated signal also increases and vice versa. In addition, measuring phase coupling between delta and alpha subbands of EEG signals through continuous CWT analysis reveals the depth of anesthesia level. As a result, awareness during anesthesia can be prevented.

[Evaluation of pain during mobilization and endotracheal aspiration in critical patients].

PubMed

Robleda, G; Roche-Campo, F; Membrilla-Martínez, L; Fernández-Lucio, A; Villamor-Vázquez, M; Merten, A; Gich, I; Mancebo, J; Català-Puigbó, E; Baños, J E

2016-03-01

1) To assess the prevalence of pain during nursing care procedures, and 2) to evaluate the usefulness of certain vital signs and the bispectral index (BIS) in detecting pain. A prospective, observational analytical study was made of procedures (endotracheal aspiration and mobilization with turning) in critically ill sedated patients on mechanical ventilation. The Behavioral Pain Scale was used to assess pain, with scores of ≥3 indicating pain. Various physiological signs and BIS values were recorded, with changes of >10% being considered clinically relevant. A total of 146 procedures in 70 patients were analyzed. Pain prevalence during the procedures was 94%. Vital signs and BIS values increased significantly during the procedures compared to resting conditions, but only the changes in BIS were considered clinically relevant. In the subgroup of patients receiving preemptive analgesia prior to the procedure, pain decreased significantly compared to the group of patients who received no such analgesia (-2 [IQR: {-5}-0] vs. 3 [IQR: 1-4]; P<.001, respectively). The procedures evaluated in this study are painful. Changes in vital signs are not good indicators of pain. Changes in BIS may provide useful information about pain, but more research is needed. The administration of preemptive analgesia decreases pain during the procedures. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Experimental verification of an interpolation algorithm for improved estimates of animal position

NASA Astrophysics Data System (ADS)

Schell, Chad; Jaffe, Jules S.

2004-07-01

This article presents experimental verification of an interpolation algorithm that was previously proposed in Jaffe [J. Acoust. Soc. Am. 105, 3168-3175 (1999)]. The goal of the algorithm is to improve estimates of both target position and target strength by minimizing a least-squares residual between noise-corrupted target measurement data and the output of a model of the sonar's amplitude response to a target at a set of known locations. Although this positional estimator was shown to be a maximum likelihood estimator, in principle, experimental verification was desired because of interest in understanding its true performance. Here, the accuracy of the algorithm is investigated by analyzing the correspondence between a target's true position and the algorithm's estimate. True target position was measured by precise translation of a small test target (bead) or from the analysis of images of fish from a coregistered optical imaging system. Results with the stationary spherical test bead in a high signal-to-noise environment indicate that a large increase in resolution is possible, while results with commercial aquarium fish indicate a smaller increase is obtainable. However, in both experiments the algorithm provides improved estimates of target position over those obtained by simply accepting the angular positions of the sonar beam with maximum output as target position. In addition, increased accuracy in target strength estimation is possible by considering the effects of the sonar beam patterns relative to the interpolated position. A benefit of the algorithm is that it can be applied ``ex post facto'' to existing data sets from commercial multibeam sonar systems when only the beam intensities have been stored after suitable calibration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sisniega, A.; Vaquero, J. J., E-mail: juanjose.vaquero@uc3m.es; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007

Purpose: The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammography. However, most of these models cannot be used directly for modeling microfocus x-ray sources due to differences in inherent filtration, energy range and/or anode material. For this reason the authors propose in this work a new model for the simulation of microfocus spectra based on existing models for mammography and radiology, modifiedmore » to compensate for the effects of inherent filtration and energy range. Methods: The authors used the radiology and mammography versions of an existing empirical model [tungsten anode spectral model interpolating polynomials (TASMIP)] as the basis of the microfocus model. First, the authors estimated the inherent filtration included in the radiology model by comparing the shape of the spectra with spectra from the mammography model. Afterwards, the authors built a unified spectra dataset by combining both models and, finally, they estimated the parameters of the new version of TASMIP for microfocus sources by calibrating against experimental exposure data from a microfocus x-ray source. The model was validated by comparing estimated and experimental exposure and attenuation data for different attenuating materials and x-ray beam peak energy values, using two different x-ray tubes. Results: Inherent filtration for the radiology spectra from TASMIP was found to be equivalent to 1.68 mm Al, as compared to spectra obtained from the mammography model. To match the experimentally measured exposure data the combined dataset required to apply a negative filtration of about 0.21 mm Al and an anode roughness of 0.003 mm W. The validation of the model against real acquired data showed errors in exposure and attenuation in line with those reported for other models for radiology or mammography. Conclusions: A new version of the TASMIP model for the estimation of x-ray spectra in microfocus x-ray sources has been developed and validated experimentally. Similarly to other versions of TASMIP, the estimation of spectra is very simple, involving only the evaluation of polynomial expressions.« less

Estimating Per-Pixel GPP of the Contiguous USA Directly from MODIS EVI Data

NASA Astrophysics Data System (ADS)

Rahman, A. F.; Sims, D. A.; El-Masri, B. Z.; Cordova, V. D.

2005-12-01

We estimated gross primary production (GPP) of the contiguous USA using enhanced vegetation index (EVI) data from NASA's moderate resolution imaging spectroradiometer (MODIS). Based on recently published values of correlation coefficients between EVI and GPP of North American vegetations, we derived GPP maps of the contiguous USA for 2001-2004, which included one La Nina year and three moderately El Nino years. The product was a truly per-pixel GPP estimate (named E-GPP), in contrast to the pseudo-continuous MOD17, the standard MODIS GPP product. We compared E-GPP with fine-scale experimental GPP data and MOD17 estimates from three Bigfoot experimental sites, and also with MOD17 estimates from the whole contiguous USA for the above-mentioned four years. For each of the '7 by 7' km Bigfoot experimental sites, E-GPP was able to track the primary production activity during the green-up period while MOD17 failed to do so. The E-GPP estimates during peak production season were similar to those from Bigfoot and MOD17 for most vegetation types except for the deciduous types, where it was lower. Annual E-GPP of the Bigfoot sites compared well with Bigfoot experimental GPP (r = 0.71) and MOD17 (r = 0.78). But for the contiguous USA for 2001-2004, annual E-GPP showed disagreement with MOD17 in both magnitude and seasonal trends for deciduous forests and grass lands. In this study we explored the reasons for this mismatch between E-GPP and MOD17 and also analyzed the uncertainties in E-GPP across multiple spatial scales. Our results show that the E-GPP, based on a simple regression model, can work as a robust alternative to MOD17 for large-area annual GPP estimation. The relative advantages of E-GPP are that it is truly per-pixel, solely dependent on remotely sensed data that is routinely available from NASA, easy to compute and has the potential of being used as an operational product.

Relative Navigation for Formation Flying of Spacecraft

NASA Technical Reports Server (NTRS)

Alonso, Roberto; Du, Ju-Young; Hughes, Declan; Junkins, John L.; Crassidis, John L.

2001-01-01

This paper presents a robust and efficient approach for relative navigation and attitude estimation of spacecraft flying in formation. This approach uses measurements from a new optical sensor that provides a line of sight vector from the master spacecraft to the secondary satellite. The overall system provides a novel, reliable, and autonomous relative navigation and attitude determination system, employing relatively simple electronic circuits with modest digital signal processing requirements and is fully independent of any external systems. Experimental calibration results are presented, which are used to achieve accurate line of sight measurements. State estimation for formation flying is achieved through an optimal observer design. Also, because the rotational and translational motions are coupled through the observation vectors, three approaches are suggested to separate both signals just for stability analysis. Simulation and experimental results indicate that the combined sensor/estimator approach provides accurate relative position and attitude estimates.

Composing problem solvers for simulation experimentation: a case study on steady state estimation.

PubMed

Leye, Stefan; Ewald, Roland; Uhrmacher, Adelinde M

2014-01-01

Simulation experiments involve various sub-tasks, e.g., parameter optimization, simulation execution, or output data analysis. Many algorithms can be applied to such tasks, but their performance depends on the given problem. Steady state estimation in systems biology is a typical example for this: several estimators have been proposed, each with its own (dis-)advantages. Experimenters, therefore, must choose from the available options, even though they may not be aware of the consequences. To support those users, we propose a general scheme to aggregate such algorithms to so-called synthetic problem solvers, which exploit algorithm differences to improve overall performance. Our approach subsumes various aggregation mechanisms, supports automatic configuration from training data (e.g., via ensemble learning or portfolio selection), and extends the plugin system of the open source modeling and simulation framework James II. We show the benefits of our approach by applying it to steady state estimation for cell-biological models.

SDR input power estimation algorithms

NASA Astrophysics Data System (ADS)

Briones, J. C.; Nappier, J. M.

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

SDR Input Power Estimation Algorithms

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

Thermal Property Parameter Estimation of TPS Materials

NASA Technical Reports Server (NTRS)

Maddren, Jesse

1998-01-01

Accurate knowledge of the thermophysical properties of TPS (thermal protection system) materials is necessary for pre-flight design and post-flight data analysis. Thermal properties, such as thermal conductivity and the volumetric specific heat, can be estimated from transient temperature measurements using non-linear parameter estimation methods. Property values are derived by minimizing a functional of the differences between measured and calculated temperatures. High temperature thermal response testing of TPS materials is usually done in arc-jet or radiant heating facilities which provide a quasi one-dimensional heating environment. Last year, under the NASA-ASEE-Stanford Fellowship Program, my work focused on developing a radiant heating apparatus. This year, I have worked on increasing the fidelity of the experimental measurements, optimizing the experimental procedures and interpreting the data.

Long-term radon concentrations estimated from 210Po embedded in glass

USGS Publications Warehouse

Lively, R.S.; Steck, D.J.

1993-01-01

Measured surface-alpha activity on glass exposed in radon chambers and houses has a linear correlation to the integrated radon exposure. Experimental results in chambers and houses have been obtained on glass exposed to radon concentrations between 100 Bq m-3 and 9 MBq m-3 for periods of a few days to several years. Theoretical calculations support the experimental results through a model that predicts the fractions of airborne activity that deposit and become embedded or adsorbed. The combination of measured activity and calculated embedded fraction for a given deposition environment can be applied to most indoor areas and produces a better estimate for lifetime radon exposure than estimates based on short-term indoor radon measurements.

Optimized parameter estimation in the presence of collective phase noise

NASA Astrophysics Data System (ADS)

Altenburg, Sanah; Wölk, Sabine; Tóth, Géza; Gühne, Otfried

2016-11-01

We investigate phase and frequency estimation with different measurement strategies under the effect of collective phase noise. First, we consider the standard linear estimation scheme and present an experimentally realizable optimization of the initial probe states by collective rotations. We identify the optimal rotation angle for different measurement times. Second, we show that subshot noise sensitivity—up to the Heisenberg limit—can be reached in presence of collective phase noise by using differential interferometry, where one part of the system is used to monitor the noise. For this, not only Greenberger-Horne-Zeilinger states but also symmetric Dicke states are suitable. We investigate the optimal splitting for a general symmetric Dicke state at both inputs and discuss possible experimental realizations of differential interferometry.

Estimating Flow-Through Balance Momentum Tares with CFD

NASA Technical Reports Server (NTRS)

Melton, John E.; James, Kevin D.; Long, Kurtis R.; Flamm, Jeffrey D.

2016-01-01

This paper describes the process used for estimating flow-through balance momentum tares. The interaction of jet engine exhausts on the BOEINGERA Hybrid Wing Body (HWB) was simulated in the NFAC 40x80 wind tunnel at NASA Ames using a pair of turbine powered simulators (TPS). High-pressure air was passed through a flow-through balance and manifold before being delivered to the TPS units. The force and moment tares that result from the internal shear and pressure distribution were estimated using CFD. Validation of the CFD simulations for these complex internal flows is a challenge, given limited experimental data due to the complications of the internal geometry. Two CFD validation efforts are documented, and comparisons with experimental data from the final model installation are provided.

Local Intrinsic Dimension Estimation by Generalized Linear Modeling.

PubMed

Hino, Hideitsu; Fujiki, Jun; Akaho, Shotaro; Murata, Noboru

2017-07-01

We propose a method for intrinsic dimension estimation. By fitting the power of distance from an inspection point and the number of samples included inside a ball with a radius equal to the distance, to a regression model, we estimate the goodness of fit. Then, by using the maximum likelihood method, we estimate the local intrinsic dimension around the inspection point. The proposed method is shown to be comparable to conventional methods in global intrinsic dimension estimation experiments. Furthermore, we experimentally show that the proposed method outperforms a conventional local dimension estimation method.

Robust Alternatives to the Standard Deviation in Processing of Physics Experimental Data

NASA Astrophysics Data System (ADS)

Shulenin, V. P.

2016-10-01

Properties of robust estimations of the scale parameter are studied. It is noted that the median of absolute deviations and the modified estimation of the average Gini differences have asymptotically normal distributions and bounded influence functions, are B-robust estimations, and hence, unlike the estimation of the standard deviation, are protected from the presence of outliers in the sample. Results of comparison of estimations of the scale parameter are given for a Gaussian model with contamination. An adaptive variant of the modified estimation of the average Gini differences is considered.

Approaches to Incorporating Late Pretests in Experiments: Evaluation of Two Early Mathematics and Self-Regulation Interventions

ERIC Educational Resources Information Center

Unlu, Fatih; Layzer, Carolyn; Clements, Douglas; Sarama, Julie; Cook, David

2013-01-01

Many educational Randomized Controlled Trials (RCTs) collect baseline versions of outcome measures (pretests) to be used in the estimation of impacts at posttest. Although pretest measures are not necessary for unbiased impact estimates in well executed experimental studies, using them increases the precision of impact estimates and reduces sample…

Estimation of Organic Vapor Breakthrough in Humidified Activated Carbon Beds: -Application of Wheeler-Jonas Equation, NIOSH MultiVapor™ and RBT (Relative Breakthrough Time)

PubMed Central

Abiko, Hironobu; Furuse, Mitsuya; Takano, Tsuguo

2016-01-01

Objectives: In the use of activated carbon beds as adsorbents for various types of organic vapor in respirator gas filters, water adsorption of the bed and test gas humidity are expected to alter the accuracy in the estimation of breakthrough data. There is increasing interest in the effects of moisture on estimation methods, and this study has investigated the effects with actual breakthrough data. Methods: We prepared several activated carbon beds preconditioned by equilibration with moisture at different relative humidities (RH=40%-70%) and a constant temperature of 20°C. Then, we measured breakthrough curves in the early region of breakthrough time for 10 types of organic vapor, and investigated the effects of moisture on estimation using the Wheeler-Jonas equation, the simulation software NIOSH MultiVapor™ 2.2.3, and RBT (Relative Breakthrough Time) proposed by Tanaka et al. Results: The Wheeler-Jonas equation showed good accordance with breakthrough curves at all RH in this study. However, the correlation coefficient decreased gradually with increasing RH regardless of type of organic vapor. Estimation of breakthrough time by MultiVapor showed good accordance with experimental data at RH=50%. In contrast, it showed discordance at high RH (>50%). RBTs reported previously were consistent with experimental data at RH=50%. On the other hand, the values of RBT changed markedly with increasing RH. Conclusions: The results of each estimation method showed good accordance with experimental data under comparatively dry conditions (RH≤50%). However, there were discrepancies under high humidified conditions, and further studies are warranted. PMID:27725483

On the dipole approximation with error estimates

NASA Astrophysics Data System (ADS)

Boßmann, Lea; Grummt, Robert; Kolb, Martin

2018-01-01

The dipole approximation is employed to describe interactions between atoms and radiation. It essentially consists of neglecting the spatial variation of the external field over the atom. Heuristically, this is justified by arguing that the wavelength is considerably larger than the atomic length scale, which holds under usual experimental conditions. We prove the dipole approximation in the limit of infinite wavelengths compared to the atomic length scale and estimate the rate of convergence. Our results include N-body Coulomb potentials and experimentally relevant electromagnetic fields such as plane waves and laser pulses.

High-pressure phase transitions - Examples of classical predictability

NASA Astrophysics Data System (ADS)

Celebonovic, Vladan

1992-09-01

The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.

Blinded sample size re-estimation in three-arm trials with 'gold standard' design.

PubMed

Mütze, Tobias; Friede, Tim

2017-10-15

In this article, we study blinded sample size re-estimation in the 'gold standard' design with internal pilot study for normally distributed outcomes. The 'gold standard' design is a three-arm clinical trial design that includes an active and a placebo control in addition to an experimental treatment. We focus on the absolute margin approach to hypothesis testing in three-arm trials at which the non-inferiority of the experimental treatment and the assay sensitivity are assessed by pairwise comparisons. We compare several blinded sample size re-estimation procedures in a simulation study assessing operating characteristics including power and type I error. We find that sample size re-estimation based on the popular one-sample variance estimator results in overpowered trials. Moreover, sample size re-estimation based on unbiased variance estimators such as the Xing-Ganju variance estimator results in underpowered trials, as it is expected because an overestimation of the variance and thus the sample size is in general required for the re-estimation procedure to eventually meet the target power. To overcome this problem, we propose an inflation factor for the sample size re-estimation with the Xing-Ganju variance estimator and show that this approach results in adequately powered trials. Because of favorable features of the Xing-Ganju variance estimator such as unbiasedness and a distribution independent of the group means, the inflation factor does not depend on the nuisance parameter and, therefore, can be calculated prior to a trial. Moreover, we prove that the sample size re-estimation based on the Xing-Ganju variance estimator does not bias the effect estimate. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

What Are the Environmental Determinants of Phenotypic Selection? A Meta-analysis of Experimental Studies.

PubMed

Caruso, Christina M; Martin, Ryan A; Sletvold, Nina; Morrissey, Michael B; Wade, Michael J; Augustine, Kate E; Carlson, Stephanie M; MacColl, Andrew D C; Siepielski, Adam M; Kingsolver, Joel G

2017-09-01

Although many selection estimates have been published, the environmental factors that cause selection to vary in space and time have rarely been identified. One way to identify these factors is by experimentally manipulating the environment and measuring selection in each treatment. We compiled and analyzed selection estimates from experimental studies. First, we tested whether the effect of manipulating the environment on selection gradients depends on taxon, trait type, or fitness component. We found that the effect of manipulating the environment was larger when selection was measured on life-history traits or via survival. Second, we tested two predictions about the environmental factors that cause variation in selection. We found support for the prediction that variation in selection is more likely to be caused by environmental factors that have a large effect on mean fitness but not for the prediction that variation is more likely to be caused by biotic factors. Third, we compared selection gradients from experimental and observational studies. We found that selection varied more among treatments in experimental studies than among spatial and temporal replicates in observational studies, suggesting that experimental studies can detect relationships between environmental factors and selection that would not be apparent in observational studies.

Characterizing Protease Specificity: How Many Substrates Do We Need?

PubMed Central

Schauperl, Michael; Fuchs, Julian E.; Waldner, Birgit J.; Huber, Roland G.; Kramer, Christian; Liedl, Klaus R.

2015-01-01

Calculation of cleavage entropies allows to quantify, map and compare protease substrate specificity by an information entropy based approach. The metric intrinsically depends on the number of experimentally determined substrates (data points). Thus a statistical analysis of its numerical stability is crucial to estimate the systematic error made by estimating specificity based on a limited number of substrates. In this contribution, we show the mathematical basis for estimating the uncertainty in cleavage entropies. Sets of cleavage entropies are calculated using experimental cleavage data and modeled extreme cases. By analyzing the underlying mathematics and applying statistical tools, a linear dependence of the metric in respect to 1/n was found. This allows us to extrapolate the values to an infinite number of samples and to estimate the errors. Analyzing the errors, a minimum number of 30 substrates was found to be necessary to characterize substrate specificity, in terms of amino acid variability, for a protease (S4-S4’) with an uncertainty of 5 percent. Therefore, we encourage experimental researchers in the protease field to record specificity profiles of novel proteases aiming to identify at least 30 peptide substrates of maximum sequence diversity. We expect a full characterization of protease specificity helpful to rationalize biological functions of proteases and to assist rational drug design. PMID:26559682

A hybrid experimental-numerical technique for determining 3D velocity fields from planar 2D PIV data

NASA Astrophysics Data System (ADS)

Eden, A.; Sigurdson, M.; Mezić, I.; Meinhart, C. D.

2016-09-01

Knowledge of 3D, three component velocity fields is central to the understanding and development of effective microfluidic devices for lab-on-chip mixing applications. In this paper we present a hybrid experimental-numerical method for the generation of 3D flow information from 2D particle image velocimetry (PIV) experimental data and finite element simulations of an alternating current electrothermal (ACET) micromixer. A numerical least-squares optimization algorithm is applied to a theory-based 3D multiphysics simulation in conjunction with 2D PIV data to generate an improved estimation of the steady state velocity field. This 3D velocity field can be used to assess mixing phenomena more accurately than would be possible through simulation alone. Our technique can also be used to estimate uncertain quantities in experimental situations by fitting the gathered field data to a simulated physical model. The optimization algorithm reduced the root-mean-squared difference between the experimental and simulated velocity fields in the target region by more than a factor of 4, resulting in an average error less than 12% of the average velocity magnitude.

Application of iterative robust model-based optimal experimental design for the calibration of biocatalytic models.

PubMed

Van Daele, Timothy; Gernaey, Krist V; Ringborg, Rolf H; Börner, Tim; Heintz, Søren; Van Hauwermeiren, Daan; Grey, Carl; Krühne, Ulrich; Adlercreutz, Patrick; Nopens, Ingmar

2017-09-01

The aim of model calibration is to estimate unique parameter values from available experimental data, here applied to a biocatalytic process. The traditional approach of first gathering data followed by performing a model calibration is inefficient, since the information gathered during experimentation is not actively used to optimize the experimental design. By applying an iterative robust model-based optimal experimental design, the limited amount of data collected is used to design additional informative experiments. The algorithm is used here to calibrate the initial reaction rate of an ω-transaminase catalyzed reaction in a more accurate way. The parameter confidence region estimated from the Fisher Information Matrix is compared with the likelihood confidence region, which is not only more accurate but also a computationally more expensive method. As a result, an important deviation between both approaches is found, confirming that linearization methods should be applied with care for nonlinear models. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1278-1293, 2017. © 2017 American Institute of Chemical Engineers.

Assessing the Accuracy of Generalized Inferences From Comparison Group Studies Using a Within-Study Comparison Approach: The Methodology.

PubMed

Jaciw, Andrew P

2016-06-01

Various studies have examined bias in impact estimates from comparison group studies (CGSs) of job training programs, and in education, where results are benchmarked against experimental results. Such within-study comparison (WSC) approaches investigate levels of bias in CGS-based impact estimates, as well as the success of various design and analytic strategies for reducing bias. This article reviews past literature and summarizes conditions under which CGSs replicate experimental benchmark results. It extends the framework to, and develops the methodology for, situations where results from CGSs are generalized to untreated inference populations. Past research is summarized; methods are developed to examine bias in program impact estimates based on cross-site comparisons in a multisite trial that are evaluated against site-specific experimental benchmarks. Students in Grades K-3 in 79 schools in Tennessee; students in Grades 4-8 in 82 schools in Alabama. Grades K-3 Stanford Achievement Test (SAT) in reading and math scores; Grades 4-8 SAT10 reading scores. Past studies show that bias in CGS-based estimates can be limited through strong design, with local matching, and appropriate analysis involving pretest covariates and variables that represent selection processes. Extension of the methodology to investigate accuracy of generalized estimates from CGSs shows bias from confounders and effect moderators. CGS results, when extrapolated to untreated inference populations, may be biased due to variation in outcomes and impact. Accounting for effects of confounders or moderators may reduce bias. © The Author(s) 2016.

Assessment of ultrasound modulation of near infrared light on the quantification of scattering coefficient.

PubMed

Singh, M Suheshkumar; Yalavarthy, Phaneendra K; Vasu, R M; Rajan, K

2010-07-01

To assess the effect of ultrasound modulation of near infrared (NIR) light on the quantification of scattering coefficient in tissue-mimicking biological phantoms. A unique method to estimate the phase of the modulated NIR light making use of only time averaged intensity measurements using a charge coupled device camera is used in this investigation. These experimental measurements from tissue-mimicking biological phantoms are used to estimate the differential pathlength, in turn leading to estimation of optical scattering coefficient. A Monte-Carlo model based numerical estimation of phase in lieu of ultrasound modulation is performed to verify the experimental results. The results indicate that the ultrasound modulation of NIR light enhances the effective scattering coefficient. The observed effective scattering coefficient enhancement in tissue-mimicking viscoelastic phantoms increases with increasing ultrasound drive voltage. The same trend is noticed as the ultrasound modulation frequency approaches the natural vibration frequency of the phantom material. The contrast enhancement is less for the stiffer (larger storage modulus) tissue, mimicking tumor necrotic core, compared to the normal tissue. The ultrasound modulation of the insonified region leads to an increase in the effective number of scattering events experienced by NIR light, increasing the measured phase, causing the enhancement in the effective scattering coefficient. The ultrasound modulation of NIR light could provide better estimation of scattering coefficient. The observed local enhancement of the effective scattering coefficient, in the ultrasound focal region, is validated using both experimental measurements and Monte-Carlo simulations.

An analytical method of estimating turbine performance

NASA Technical Reports Server (NTRS)

Kochendorfer, Fred D; Nettles, J Cary

1949-01-01

A method is developed by which the performance of a turbine over a range of operating conditions can be analytically estimated from the blade angles and flow areas. In order to use the method, certain coefficients that determine the weight flow and the friction losses must be approximated. The method is used to calculate the performance of the single-stage turbine of a commercial aircraft gas-turbine engine and the calculated performance is compared with the performance indicated by experimental data. For the turbine of the typical example, the assumed pressure losses and the tuning angles give a calculated performance that represents the trends of the experimental performance with reasonable accuracy. The exact agreement between analytical performance and experimental performance is contingent upon the proper selection of a blading-loss parameter.

On the use of the noncentral chi-square density function for the distribution of helicopter spectral estimates

NASA Technical Reports Server (NTRS)

Garber, Donald P.

1993-01-01

A probability density function for the variability of ensemble averaged spectral estimates from helicopter acoustic signals in Gaussian background noise was evaluated. Numerical methods for calculating the density function and for determining confidence limits were explored. Density functions were predicted for both synthesized and experimental data and compared with observed spectral estimate variability.

Health insurance for the poor: impact on catastrophic and out-of-pocket health expenditures in Mexico

PubMed Central

Galárraga, Omar; Salinas-Rodríguez, Aarón; Sesma-Vázquez, Sergio

2009-01-01

The goal of Seguro Popular (SP) in Mexico was to improve the financial protection of the uninsured population against excessive health expenditures. This paper estimates the impact of SP on catastrophic health expenditures (CHE), as well as out-of-pocket (OOP) health expenditures, from two different sources. First, we use the SP Impact Evaluation Survey (2005–2006), and compare the instrumental variables (IV) results with the experimental benchmark. Then, we use the same IV methods with the National Health and Nutrition Survey (ENSANUT 2006). We estimate naïve models, assuming exogeneity, and contrast them with IV models that take advantage of the specific SP implementation mechanisms for identification. The IV models estimated included two-stage least squares (2SLS), bivariate probit, and two-stage residual inclusion (2SRI) models. Instrumental variables estimates resulted in comparable estimates against the “gold standard.” Instrumental variables estimates indicate a reduction of 54% in catastrophic expenditures at the national level. SP beneficiaries also had lower expenditures on outpatient and medicine expenditures. The selection-corrected protective effect is found not only in the limited experimental dataset, but also at the national level. PMID:19756796

Health insurance for the poor: impact on catastrophic and out-of-pocket health expenditures in Mexico.

PubMed

Galárraga, Omar; Sosa-Rubí, Sandra G; Salinas-Rodríguez, Aarón; Sesma-Vázquez, Sergio

2010-10-01

The goal of Seguro Popular (SP) in Mexico was to improve the financial protection of the uninsured population against excessive health expenditures. This paper estimates the impact of SP on catastrophic health expenditures (CHE), as well as out-of-pocket (OOP) health expenditures, from two different sources. First, we use the SP Impact Evaluation Survey (2005-2006), and compare the instrumental variables (IV) results with the experimental benchmark. Then, we use the same IV methods with the National Health and Nutrition Survey (ENSANUT 2006). We estimate naïve models, assuming exogeneity, and contrast them with IV models that take advantage of the specific SP implementation mechanisms for identification. The IV models estimated included two-stage least squares (2SLS), bivariate probit, and two-stage residual inclusion (2SRI) models. Instrumental variables estimates resulted in comparable estimates against the "gold standard." Instrumental variables estimates indicate a reduction of 54% in catastrophic expenditures at the national level. SP beneficiaries also had lower expenditures on outpatient and medicine expenditures. The selection-corrected protective effect is found not only in the limited experimental dataset, but also at the national level.

Lesion contrast and detection using sonoelastographic shear velocity imaging: preliminary results

NASA Astrophysics Data System (ADS)

Hoyt, Kenneth; Parker, Kevin J.

2007-03-01

This paper assesses lesion contrast and detection using sonoelastographic shear velocity imaging. Shear wave interference patterns, termed crawling waves, for a two phase medium were simulated assuming plane wave conditions. Shear velocity estimates were computed using a spatial autocorrelation algorithm that operates in the direction of shear wave propagation for a given kernel size. Contrast was determined by analyzing shear velocity estimate transition between mediums. Experimental results were obtained using heterogeneous phantoms with spherical inclusions (5 or 10 mm in diameter) characterized by elevated shear velocities. Two vibration sources were applied to opposing phantom edges and scanned (orthogonal to shear wave propagation) with an ultrasound scanner equipped for sonoelastography. Demodulated data was saved and transferred to an external computer for processing shear velocity images. Simulation results demonstrate shear velocity transition between contrasting mediums is governed by both estimator kernel size and source vibration frequency. Experimental results from phantoms further indicates that decreasing estimator kernel size produces corresponding decrease in shear velocity estimate transition between background and inclusion material albeit with an increase in estimator noise. Overall, results demonstrate the ability to generate high contrast shear velocity images using sonoelastographic techniques and detect millimeter-sized lesions.

Interaction force and motion estimators facilitating impedance control of the upper limb rehabilitation robot.

PubMed

Mancisidor, Aitziber; Zubizarreta, Asier; Cabanes, Itziar; Bengoa, Pablo; Jung, Je Hyung

2017-07-01

In order to enhance the performance of rehabilitation robots, it is imperative to know both force and motion caused by the interaction between user and robot. However, common direct measurement of both signals through force and motion sensors not only increases the complexity of the system but also impedes affordability of the system. As an alternative of the direct measurement, in this work, we present new force and motion estimators for the proper control of the upper-limb rehabilitation Universal Haptic Pantograph (UHP) robot. The estimators are based on the kinematic and dynamic model of the UHP and the use of signals measured by means of common low-cost sensors. In order to demonstrate the effectiveness of the estimators, several experimental tests were carried out. The force and impedance control of the UHP was implemented first by directly measuring the interaction force using accurate extra sensors and the robot performance was compared to the case where the proposed estimators replace the direct measured values. The experimental results reveal that the controller based on the estimators has similar performance to that using direct measurement (less than 1 N difference in root mean square error between two cases), indicating that the proposed force and motion estimators can facilitate implementation of interactive controller for the UHP in robotmediated rehabilitation trainings.

Estimation of the ionic charge of non-metallic species into an electrical discharge through a web application

NASA Astrophysics Data System (ADS)

Pérez Gutiérrez, B. R.; Vera-Rivera, F. H.; Niño, E. D. V.

2016-08-01

Estimate the ionic charge generated in electrical discharges will allow us to know more accurately the concentration of ions implanted on the surfaces of nonmetallic solids. For this reason, in this research a web application was developed to allow us to calculate the ionic charge generated in an electrical discharge from the experimental parameters established in an ion implantation process performed in the JUPITER (Joint Universal Plasma and Ion Technologies Experimental Reactor) reactor. The estimated value of the ionic charge will be determined from data acquired on an oscilloscope, during startup and shutdown of electrical discharge, which will then be analyzed and processed. The study will provide best developments with regard to the application of ion implantation in various industrial sectors.

Estimation of the activation energy in the Belousov-Zhabotinsky reaction by temperature effect on excitable waves.

PubMed

Zhang, Jinzhong; Zhou, Luqun; Ouyang, Qi

2007-02-15

We report the temperature effect on the propagation of excitable traveling waves in a quasi-two-dimensional Belousov-Zhabotinsky reaction-diffusion system. The onset of excitable waves as a function of the sulfuric acid concentration and temperature is identified, on which the sulfuric acid concentration exhibits an Arrhenius dependence on temperature. On the basis of this experimental data, the activation energy of the self-catalyzed reaction in the Oregonator model is estimated to be 83-113 kJ/mol, which is further supported by our numerical simulations. The estimation proceeds without analyzing detailed reaction steps but rather through observing the global dynamic behaviors in the BZ reaction. For a supplement, the wave propagation velocities are calculated based on our results and compared with the experimental observations.

Experimental Quasi-Microwave Whole-Body Averaged SAR Estimation Method Using Cylindrical-External Field Scanning

NASA Astrophysics Data System (ADS)

Kawamura, Yoshifumi; Hikage, Takashi; Nojima, Toshio

The aim of this study is to develop a new whole-body averaged specific absorption rate (SAR) estimation method based on the external-cylindrical field scanning technique. This technique is adopted with the goal of simplifying the dosimetry estimation of human phantoms that have different postures or sizes. An experimental scaled model system is constructed. In order to examine the validity of the proposed method for realistic human models, we discuss the pros and cons of measurements and numerical analyses based on the finite-difference time-domain (FDTD) method. We consider the anatomical European human phantoms and plane-wave in the 2GHz mobile phone frequency band. The measured whole-body averaged SAR results obtained by the proposed method are compared with the results of the FDTD analyses.

Estimation of beam material random field properties via sensitivity-based model updating using experimental frequency response functions

NASA Astrophysics Data System (ADS)

Machado, M. R.; Adhikari, S.; Dos Santos, J. M. C.; Arruda, J. R. F.

2018-03-01

Structural parameter estimation is affected not only by measurement noise but also by unknown uncertainties which are present in the system. Deterministic structural model updating methods minimise the difference between experimentally measured data and computational prediction. Sensitivity-based methods are very efficient in solving structural model updating problems. Material and geometrical parameters of the structure such as Poisson's ratio, Young's modulus, mass density, modal damping, etc. are usually considered deterministic and homogeneous. In this paper, the distributed and non-homogeneous characteristics of these parameters are considered in the model updating. The parameters are taken as spatially correlated random fields and are expanded in a spectral Karhunen-Loève (KL) decomposition. Using the KL expansion, the spectral dynamic stiffness matrix of the beam is expanded as a series in terms of discretized parameters, which can be estimated using sensitivity-based model updating techniques. Numerical and experimental tests involving a beam with distributed bending rigidity and mass density are used to verify the proposed method. This extension of standard model updating procedures can enhance the dynamic description of structural dynamic models.

Base Pressure at Supersonic Speeds on Two-dimensional Airfoils and on Bodies of Revolution with and Without Fins Having Turbulent Boundary Layers

NASA Technical Reports Server (NTRS)

LOVE EUGENE S

1957-01-01

An analysis has been made of available experimental data to show the effects of most of the variables that are more predominant in determining base pressure at supersonic speeds. The analysis covers base pressures for two-dimensional airfoils and for bodies of revolution with and without stabilizing fins and is restricted to turbulent boundary layers. The present status of available experimental information is summarized as are the existing methods for predicting base pressure. A simple semiempirical method is presented for estimating base pressure. For two-dimensional bases, this method stems from an analogy established between the base-pressure phenomena and the peak pressure rise associated with the separation of the boundary layer. An analysis made for axially symmetric flow indicates that the base pressure for bodies of revolution is subject to the same analogy. Based upon the methods presented, estimations are made of such effects as Mach number, angle of attack, boattailing, fineness ratio, and fins. These estimations give fair predictions of experimental results. (author)

Large electroweak penguin contribution in B{yields}K{pi} and {pi}{pi} decay modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishima, Satoshi; Yoshikawa, Tadashi

2004-11-01

We discuss a possibility of large electroweak penguin contribution in B{yields}K{pi} and {pi}{pi} from recent experimental data. The experimental data may be suggesting that there are some discrepancies between the data and theoretical estimation in the branching ratios of them. In B{yields}K{pi} decays, to explain it, a large electroweak penguin contribution and large strong phase differences seem to be needed. The contributions should appear also in B{yields}{pi}{pi}. We show, as an example, a solution to solve the discrepancies in both B{yields}K{pi} and B{yields}{pi}{pi}. However the magnitude of the parameters and the strong phase estimated from experimental data are quite largemore » compared with the theoretical estimations. It may be suggesting some new physics effects are included in these processes. We will have to discuss about the dependence of the new physics. To explain both modes at once, we may need large electroweak penguin contribution with new weak phases and some SU(3) breaking effects by new physics in both QCD and electroweak penguin-type processes.« less

GD SDR Automatic Gain Control Characterization Testing

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showi ng how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

Modelling mass transfer during venting/soil vapour extraction: Non-aqueous phase liquid/gas mass transfer coefficient estimation

NASA Astrophysics Data System (ADS)

Esrael, D.; Kacem, M.; Benadda, B.

2017-07-01

We investigate how the simulation of the venting/soil vapour extraction (SVE) process is affected by the mass transfer coefficient, using a model comprising five partial differential equations describing gas flow and mass conservation of phases and including an expression accounting for soil saturation conditions. In doing so, we test five previously reported quations for estimating the non-aqueous phase liquid (NAPL)/gas initial mass transfer coefficient and evaluate an expression that uses a reference NAPL saturation. Four venting/SVE experiments utilizing a sand column are performed with dry and non-saturated sand at low and high flow rates, and the obtained experimental results are subsequently simulated, revealing that hydrodynamic dispersion cannot be neglected in the estimation of the mass transfer coefficient, particularly in the case of low velocities. Among the tested models, only the analytical solution of a convection-dispersion equation and the equation proposed herein are suitable for correctly modelling the experimental results, with the developed model representing the best choice for correctly simulating the experimental results and the tailing part of the extracted gas concentration curve.

GD SDR Automatic Gain Control Characterization Testing

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

Stability and Control Estimation Flight Test Results for the SR-71 Aircraft With Externally Mounted Experiments

NASA Technical Reports Server (NTRS)

Moes, Timothy R.; Iliff, Kenneth

2002-01-01

A maximum-likelihood output-error parameter estimation technique is used to obtain stability and control derivatives for the NASA Dryden Flight Research Center SR-71A airplane and for configurations that include experiments externally mounted to the top of the fuselage. This research is being done as part of the envelope clearance for the new experiment configurations. Flight data are obtained at speeds ranging from Mach 0.4 to Mach 3.0, with an extensive amount of test points at approximately Mach 1.0. Pilot-input pitch and yaw-roll doublets are used to obtain the data. This report defines the parameter estimation technique used, presents stability and control derivative results, and compares the derivatives for the three configurations tested. The experimental configurations studied generally show acceptable stability, control, trim, and handling qualities throughout the Mach regimes tested. The reduction of directional stability for the experimental configurations is the most significant aerodynamic effect measured and identified as a design constraint for future experimental configurations. This report also shows the significant effects of aircraft flexibility on the stability and control derivatives.

Estimation of the Reactive Flow Model Parameters for an Ammonium Nitrate-Based Emulsion Explosive Using Genetic Algorithms

NASA Astrophysics Data System (ADS)

Ribeiro, J. B.; Silva, C.; Mendes, R.

2010-10-01

A real coded genetic algorithm methodology that has been developed for the estimation of the parameters of the reaction rate equation of the Lee-Tarver reactive flow model is described in detail. This methodology allows, in a single optimization procedure, using only one experimental result and, without the need of any starting solution, to seek the 15 parameters of the reaction rate equation that fit the numerical to the experimental results. Mass averaging and the plate-gap model have been used for the determination of the shock data used in the unreacted explosive JWL equation of state (EOS) assessment and the thermochemical code THOR retrieved the data used in the detonation products' JWL EOS assessments. The developed methodology was applied for the estimation of the referred parameters for an ammonium nitrate-based emulsion explosive using poly(methyl methacrylate) (PMMA)-embedded manganin gauge pressure-time data. The obtained parameters allow a reasonably good description of the experimental data and show some peculiarities arising from the intrinsic nature of this kind of composite explosive.

Refining Markov state models for conformational dynamics using ensemble-averaged data and time-series trajectories

NASA Astrophysics Data System (ADS)

Matsunaga, Y.; Sugita, Y.

2018-06-01

A data-driven modeling scheme is proposed for conformational dynamics of biomolecules based on molecular dynamics (MD) simulations and experimental measurements. In this scheme, an initial Markov State Model (MSM) is constructed from MD simulation trajectories, and then, the MSM parameters are refined using experimental measurements through machine learning techniques. The second step can reduce the bias of MD simulation results due to inaccurate force-field parameters. Either time-series trajectories or ensemble-averaged data are available as a training data set in the scheme. Using a coarse-grained model of a dye-labeled polyproline-20, we compare the performance of machine learning estimations from the two types of training data sets. Machine learning from time-series data could provide the equilibrium populations of conformational states as well as their transition probabilities. It estimates hidden conformational states in more robust ways compared to that from ensemble-averaged data although there are limitations in estimating the transition probabilities between minor states. We discuss how to use the machine learning scheme for various experimental measurements including single-molecule time-series trajectories.

ADMIT: a toolbox for guaranteed model invalidation, estimation and qualitative–quantitative modeling

PubMed Central

Streif, Stefan; Savchenko, Anton; Rumschinski, Philipp; Borchers, Steffen; Findeisen, Rolf

2012-01-01

Summary: Often competing hypotheses for biochemical networks exist in the form of different mathematical models with unknown parameters. Considering available experimental data, it is then desired to reject model hypotheses that are inconsistent with the data, or to estimate the unknown parameters. However, these tasks are complicated because experimental data are typically sparse, uncertain, and are frequently only available in form of qualitative if–then observations. ADMIT (Analysis, Design and Model Invalidation Toolbox) is a MatLabTM-based tool for guaranteed model invalidation, state and parameter estimation. The toolbox allows the integration of quantitative measurement data, a priori knowledge of parameters and states, and qualitative information on the dynamic or steady-state behavior. A constraint satisfaction problem is automatically generated and algorithms are implemented for solving the desired estimation, invalidation or analysis tasks. The implemented methods built on convex relaxation and optimization and therefore provide guaranteed estimation results and certificates for invalidity. Availability: ADMIT, tutorials and illustrative examples are available free of charge for non-commercial use at http://ifatwww.et.uni-magdeburg.de/syst/ADMIT/ Contact: stefan.streif@ovgu.de PMID:22451270

ADMIT: a toolbox for guaranteed model invalidation, estimation and qualitative-quantitative modeling.

PubMed

Streif, Stefan; Savchenko, Anton; Rumschinski, Philipp; Borchers, Steffen; Findeisen, Rolf

2012-05-01

Often competing hypotheses for biochemical networks exist in the form of different mathematical models with unknown parameters. Considering available experimental data, it is then desired to reject model hypotheses that are inconsistent with the data, or to estimate the unknown parameters. However, these tasks are complicated because experimental data are typically sparse, uncertain, and are frequently only available in form of qualitative if-then observations. ADMIT (Analysis, Design and Model Invalidation Toolbox) is a MatLab(TM)-based tool for guaranteed model invalidation, state and parameter estimation. The toolbox allows the integration of quantitative measurement data, a priori knowledge of parameters and states, and qualitative information on the dynamic or steady-state behavior. A constraint satisfaction problem is automatically generated and algorithms are implemented for solving the desired estimation, invalidation or analysis tasks. The implemented methods built on convex relaxation and optimization and therefore provide guaranteed estimation results and certificates for invalidity. ADMIT, tutorials and illustrative examples are available free of charge for non-commercial use at http://ifatwww.et.uni-magdeburg.de/syst/ADMIT/

Local Spatial Obesity Analysis and Estimation Using Online Social Network Sensors.

PubMed

Sun, Qindong; Wang, Nan; Li, Shancang; Zhou, Hongyi

2018-03-15

Recently, the online social networks (OSNs) have received considerable attentions as a revolutionary platform to offer users massive social interaction among users that enables users to be more involved in their own healthcare. The OSNs have also promoted increasing interests in the generation of analytical, data models in health informatics. This paper aims at developing an obesity identification, analysis, and estimation model, in which each individual user is regarded as an online social network 'sensor' that can provide valuable health information. The OSN-based obesity analytic model requires each sensor node in an OSN to provide associated features, including dietary habit, physical activity, integral/incidental emotions, and self-consciousness. Based on the detailed measurements on the correlation of obesity and proposed features, the OSN obesity analytic model is able to estimate the obesity rate in certain urban areas and the experimental results demonstrate a high success estimation rate. The measurements and estimation experimental findings created by the proposed obesity analytic model show that the online social networks could be used in analyzing the local spatial obesity problems effectively. Copyright © 2018. Published by Elsevier Inc.

Timber marking costs in spruce-fir: experience on the Penobscot Experimental Forest

Treesearch

Paul E. Sendak

2002-01-01

In the application of partial harvests, time needs to be allocated to marking trees to be cut. On the Penobscot Experimental Forest located in Maine, eight major experimental treatments have been applied to northern conifer stands for more than 40 yr. Data recorded at the time of marking were used to estimate the time required to mark trees for harvest. A simple linear...

Simple Form of MMSE Estimator for Super-Gaussian Prior Densities

NASA Astrophysics Data System (ADS)

Kittisuwan, Pichid

2015-04-01

The denoising method that become popular in recent years for additive white Gaussian noise (AWGN) are Bayesian estimation techniques e.g., maximum a posteriori (MAP) and minimum mean square error (MMSE). In super-Gaussian prior densities, it is well known that the MMSE estimator in such a case has a complicated form. In this work, we derive the MMSE estimation with Taylor series. We show that the proposed estimator also leads to a simple formula. An extension of this estimator to Pearson type VII prior density is also offered. The experimental result shows that the proposed estimator to the original MMSE nonlinearity is reasonably good.

Dynamical Model of Drug Accumulation in Bacteria: Sensitivity Analysis and Experimentally Testable Predictions

DOE PAGES

Vesselinova, Neda; Alexandrov, Boian; Wall, Michael E.

2016-11-08

We present a dynamical model of drug accumulation in bacteria. The model captures key features in experimental time courses on ofloxacin accumulation: initial uptake; two-phase response; and long-term acclimation. In combination with experimental data, the model provides estimates of import and export rates in each phase, the time of entry into the second phase, and the decrease of internal drug during acclimation. Global sensitivity analysis, local sensitivity analysis, and Bayesian sensitivity analysis of the model provide information about the robustness of these estimates, and about the relative importance of different parameters in determining the features of the accumulation time coursesmore » in three different bacterial species: Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The results lead to experimentally testable predictions of the effects of membrane permeability, drug efflux and trapping (e.g., by DNA binding) on drug accumulation. A key prediction is that a sudden increase in ofloxacin accumulation in both E. coli and S. aureus is accompanied by a decrease in membrane permeability.« less

Dynamical Model of Drug Accumulation in Bacteria: Sensitivity Analysis and Experimentally Testable Predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vesselinova, Neda; Alexandrov, Boian; Wall, Michael E.

We present a dynamical model of drug accumulation in bacteria. The model captures key features in experimental time courses on ofloxacin accumulation: initial uptake; two-phase response; and long-term acclimation. In combination with experimental data, the model provides estimates of import and export rates in each phase, the time of entry into the second phase, and the decrease of internal drug during acclimation. Global sensitivity analysis, local sensitivity analysis, and Bayesian sensitivity analysis of the model provide information about the robustness of these estimates, and about the relative importance of different parameters in determining the features of the accumulation time coursesmore » in three different bacterial species: Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The results lead to experimentally testable predictions of the effects of membrane permeability, drug efflux and trapping (e.g., by DNA binding) on drug accumulation. A key prediction is that a sudden increase in ofloxacin accumulation in both E. coli and S. aureus is accompanied by a decrease in membrane permeability.« less

Experimental demonstration of non-iterative interpolation-based partial ICI compensation in100G RGI-DP-CO-OFDM transport systems.

PubMed

Mousa-Pasandi, Mohammad E; Zhuge, Qunbi; Xu, Xian; Osman, Mohamed M; El-Sahn, Ziad A; Chagnon, Mathieu; Plant, David V

2012-07-02

We experimentally investigate the performance of a low-complexity non-iterative phase noise induced inter-carrier interference (ICI) compensation algorithm in reduced-guard-interval dual-polarization coherent-optical orthogonal-frequency-division-multiplexing (RGI-DP-CO-OFDM) transport systems. This interpolation-based ICI compensator estimates the time-domain phase noise samples by a linear interpolation between the CPE estimates of the consecutive OFDM symbols. We experimentally study the performance of this scheme for a 28 Gbaud QPSK RGI-DP-CO-OFDM employing a low cost distributed feedback (DFB) laser. Experimental results using a DFB laser with the linewidth of 2.6 MHz demonstrate 24% and 13% improvement in transmission reach with respect to the conventional equalizer (CE) in presence of weak and strong dispersion-enhanced-phase-noise (DEPN), respectively. A brief analysis of the computational complexity of this scheme in terms of the number of required complex multiplications is provided. This practical approach does not suffer from error propagation while enjoying low computational complexity.

Alcohol and Sexuality Research in the AIDS Era: Trends in Publication Activity, Target Populations and Research Design

PubMed Central

George, William H.

2009-01-01

Research addressing relationships between alcohol and human sexuality has proliferated, due in part to efforts to characterize alcohol's role in HIV risk behavior. This study provides a descriptive review of the alcohol–sexuality literature, using abstracts from 264 identified studies to estimate changes in publication activity, target populations, and the prevalence of HIV-related studies over time. We also examine methodological trends by estimating the prevalence of experimental vs. non-experimental studies. Findings show considerable increases in research activity and diversity of populations studied since the mid-1980's and highlight the emergence of HIV-related studies as a focal point of alcohol–sexuality research efforts. Results also demonstrate a substantial decline in the proportion of studies utilizing experimental methods, in part because of frequent use of non-experimental approaches in studies of alcohol and HIV risk behavior. We discuss implications and review the role of experiments in evaluating causal relationships between alcohol and sexual risk behavior. PMID:16897352

Alcohol and sexuality research in the AIDS era: trends in publication activity, target populations and research design.

PubMed

Hendershot, Christian S; George, William H

2007-03-01

Research addressing relationships between alcohol and human sexuality has proliferated, due in part to efforts to characterize alcohol's role in HIV risk behavior. This study provides a descriptive review of the alcohol-sexuality literature, using abstracts from 264 identified studies to estimate changes in publication activity, target populations, and the prevalence of HIV-related studies over time. We also examine methodological trends by estimating the prevalence of experimental vs. non-experimental studies. Findings show considerable increases in research activity and diversity of populations studied since the mid-1980's and highlight the emergence of HIV-related studies as a focal point of alcohol-sexuality research efforts. Results also demonstrate a substantial decline in the proportion of studies utilizing experimental methods, in part because of frequent use of non-experimental approaches in studies of alcohol and HIV risk behavior. We discuss implications and review the role of experiments in evaluating causal relationships between alcohol and sexual risk behavior.

Estimating the Stoichiometry of HIV Neutralization

PubMed Central

Magnus, Carsten; Regoes, Roland R.

2010-01-01

HIV-1 virions infect target cells by first establishing contact between envelope glycoprotein trimers on the virion's surface and CD4 receptors on a target cell, recruiting co-receptors, fusing with the cell membrane and finally releasing the genetic material into the target cell. Specific experimental setups allow the study of the number of trimer-receptor-interactions needed for infection, i.e., the stoichiometry of entry and also the number of antibodies needed to prevent one trimer from engaging successfully in the entry process, i.e., the stoichiometry of (trimer) neutralization. Mathematical models are required to infer the stoichiometric parameters from these experimental data. Recently, we developed mathematical models for the estimations of the stoichiometry of entry [1]. In this article, we show how our models can be extended to investigate the stoichiometry of trimer neutralization. We study how various biological parameters affect the estimate of the stoichiometry of neutralization. We find that the distribution of trimer numbers—which is also an important determinant of the stoichiometry of entry—influences the estimated value of the stoichiometry of neutralization. In contrast, other parameters, which characterize the experimental system, diminish the information we can extract from the data about the stoichiometry of neutralization, and thus reduce our confidence in the estimate. We illustrate the use of our models by re-analyzing previously published data on the neutralization sensitivity [2], which contains measurements of neutralization sensitivity of viruses with different envelope proteins to antibodies with various specificities. Our mathematical framework represents the formal basis for the estimation of the stoichiometry of neutralization. Together with the stoichiometry of entry, the stoichiometry of trimer neutralization will allow one to calculate how many antibodies are required to neutralize a virion or even an entire population of virions. PMID:20333245

Experimental demonstration of OFDM/OQAM transmission with DFT-based channel estimation for visible laser light communications

NASA Astrophysics Data System (ADS)

He, Jing; Shi, Jin; Deng, Rui; Chen, Lin

2017-08-01

Recently, visible light communication (VLC) based on light-emitting diodes (LEDs) is considered as a candidate technology for fifth-generation (5G) communications, VLC is free of electromagnetic interference and it can simplify the integration of VLC into heterogeneous wireless networks. Due to the data rates of VLC system limited by the low pumping efficiency, small output power and narrow modulation bandwidth, visible laser light communication (VLLC) system with laser diode (LD) has paid more attention. In addition, orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) is currently attracting attention in optical communications. Due to the non-requirement of cyclic prefix (CP) and time-frequency domain well-localized pulse shapes, it can achieve high spectral efficiency. Moreover, OFDM/OQAM has lower out-of-band power leakage so that it increases the system robustness against inter-carrier interference (ICI) and frequency offset. In this paper, a Discrete Fourier Transform (DFT)-based channel estimation scheme combined with the interference approximation method (IAM) is proposed and experimentally demonstrated for VLLC OFDM/OQAM system. The performance of VLLC OFDM/OQAM system with and without DFT-based channel estimation is investigated. Moreover, the proposed DFT-based channel estimation scheme and the intra-symbol frequency-domain averaging (ISFA)-based method are also compared for the VLLC OFDM/OQAM system. The experimental results show that, the performance of EVM using the DFT-based channel estimation scheme is improved about 3dB compared with the conventional IAM method. In addition, the DFT-based channel estimation scheme can resist the channel noise effectively than that of the ISFA-based method.

Computation of transmitted and received B1 fields in magnetic resonance imaging.

PubMed

Milles, Julien; Zhu, Yue Min; Chen, Nan-Kuei; Panych, Lawrence P; Gimenez, Gérard; Guttmann, Charles R G

2006-05-01

Computation of B1 fields is a key issue for determination and correction of intensity nonuniformity in magnetic resonance images. This paper presents a new method for computing transmitted and received B1 fields. Our method combines a modified MRI acquisition protocol and an estimation technique based on the Levenberg-Marquardt algorithm and spatial filtering. It enables accurate estimation of transmitted and received B1 fields for both homogeneous and heterogeneous objects. The method is validated using numerical simulations and experimental data from phantom and human scans. The experimental results are in agreement with theoretical expectations.

An improved hybrid of particle swarm optimization and the gravitational search algorithm to produce a kinetic parameter estimation of aspartate biochemical pathways.

PubMed

Ismail, Ahmad Muhaimin; Mohamad, Mohd Saberi; Abdul Majid, Hairudin; Abas, Khairul Hamimah; Deris, Safaai; Zaki, Nazar; Mohd Hashim, Siti Zaiton; Ibrahim, Zuwairie; Remli, Muhammad Akmal

2017-12-01

Mathematical modelling is fundamental to understand the dynamic behavior and regulation of the biochemical metabolisms and pathways that are found in biological systems. Pathways are used to describe complex processes that involve many parameters. It is important to have an accurate and complete set of parameters that describe the characteristics of a given model. However, measuring these parameters is typically difficult and even impossible in some cases. Furthermore, the experimental data are often incomplete and also suffer from experimental noise. These shortcomings make it challenging to identify the best-fit parameters that can represent the actual biological processes involved in biological systems. Computational approaches are required to estimate these parameters. The estimation is converted into multimodal optimization problems that require a global optimization algorithm that can avoid local solutions. These local solutions can lead to a bad fit when calibrating with a model. Although the model itself can potentially match a set of experimental data, a high-performance estimation algorithm is required to improve the quality of the solutions. This paper describes an improved hybrid of particle swarm optimization and the gravitational search algorithm (IPSOGSA) to improve the efficiency of a global optimum (the best set of kinetic parameter values) search. The findings suggest that the proposed algorithm is capable of narrowing down the search space by exploiting the feasible solution areas. Hence, the proposed algorithm is able to achieve a near-optimal set of parameters at a fast convergence speed. The proposed algorithm was tested and evaluated based on two aspartate pathways that were obtained from the BioModels Database. The results show that the proposed algorithm outperformed other standard optimization algorithms in terms of accuracy and near-optimal kinetic parameter estimation. Nevertheless, the proposed algorithm is only expected to work well in small scale systems. In addition, the results of this study can be used to estimate kinetic parameter values in the stage of model selection for different experimental conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Maxwell-Stefan diffusion coefficient estimation for ternary systems: an ideal ternary alcohol system.

PubMed

Allie-Ebrahim, Tariq; Zhu, Qingyu; Bräuer, Pierre; Moggridge, Geoff D; D'Agostino, Carmine

2017-06-21

The Maxwell-Stefan model is a popular diffusion model originally developed to model diffusion of gases, which can be considered thermodynamically ideal mixtures, although its application has been extended to model diffusion in non-ideal liquid mixtures as well. A drawback of the model is that it requires the Maxwell-Stefan diffusion coefficients, which are not based on measurable quantities but they have to be estimated. As a result, numerous estimation methods, such as the Darken model, have been proposed to estimate these diffusion coefficients. However, the Darken model was derived, and is only well defined, for binary systems. This model has been extended to ternary systems according to two proposed forms, one by R. Krishna and J. M. van Baten, Ind. Eng. Chem. Res., 2005, 44, 6939-6947 and the other by X. Liu, T. J. H. Vlugt and A. Bardow, Ind. Eng. Chem. Res., 2011, 50, 10350-10358. In this paper, the two forms have been analysed against the ideal ternary system of methanol/butan-1-ol/propan-1-ol and using experimental values of self-diffusion coefficients. In particular, using pulsed gradient stimulated echo nuclear magnetic resonance (PGSTE-NMR) we have measured the self-diffusion coefficients in various methanol/butan-1-ol/propan-1-ol mixtures. The experimental values of self-diffusion coefficients were then used as the input data required for the Darken model. The predictions of the two proposed multicomponent forms of this model were then compared to experimental values of mutual diffusion coefficients for the ideal alcohol ternary system. This experimental-based approach showed that the Liu's model gives better predictions compared to that of Krishna and van Baten, although it was only accurate to within 26%. Nonetheless, the multicomponent Darken model in conjunction with self-diffusion measurements from PGSTE-NMR represents an attractive method for a rapid estimation of mutual diffusion in multicomponent systems, especially when compared to exhaustive MD simulations.

A confidence building exercise in data and identifiability: Modeling cancer chemotherapy as a case study.

PubMed

Eisenberg, Marisa C; Jain, Harsh V

2017-10-27

Mathematical modeling has a long history in the field of cancer therapeutics, and there is increasing recognition that it can help uncover the mechanisms that underlie tumor response to treatment. However, making quantitative predictions with such models often requires parameter estimation from data, raising questions of parameter identifiability and estimability. Even in the case of structural (theoretical) identifiability, imperfect data and the resulting practical unidentifiability of model parameters can make it difficult to infer the desired information, and in some cases, to yield biologically correct inferences and predictions. Here, we examine parameter identifiability and estimability using a case study of two compartmental, ordinary differential equation models of cancer treatment with drugs that are cell cycle-specific (taxol) as well as non-specific (oxaliplatin). We proceed through model building, structural identifiability analysis, parameter estimation, practical identifiability analysis and its biological implications, as well as alternative data collection protocols and experimental designs that render the model identifiable. We use the differential algebra/input-output relationship approach for structural identifiability, and primarily the profile likelihood approach for practical identifiability. Despite the models being structurally identifiable, we show that without consideration of practical identifiability, incorrect cell cycle distributions can be inferred, that would result in suboptimal therapeutic choices. We illustrate the usefulness of estimating practically identifiable combinations (in addition to the more typically considered structurally identifiable combinations) in generating biologically meaningful insights. We also use simulated data to evaluate how the practical identifiability of the model would change under alternative experimental designs. These results highlight the importance of understanding the underlying mechanisms rather than purely using parsimony or information criteria/goodness-of-fit to decide model selection questions. The overall roadmap for identifiability testing laid out here can be used to help provide mechanistic insight into complex biological phenomena, reduce experimental costs, and optimize model-driven experimentation. Copyright © 2017. Published by Elsevier Ltd.

Random Measurement Error Does Not Bias the Treatment Effect Estimate in the Regression-Discontinuity Design. II. When an Interaction Effect Is Present.

ERIC Educational Resources Information Center

Trochim, William M. K.; And Others

1991-01-01

The regression-discontinuity design involving a treatment interaction effect (TIE), pretest-posttest functional form specification, and choice of point-of-estimation of the TIE are examined. Formulas for controlling the magnitude of TIE in simulations can be used for simulating the randomized experimental case where estimation is not at the…

Evaluating the microscopic fecal technique for estimating hard mast in turkey diets

Treesearch

Mark A. Rumble; Stanley H. Anderson

1993-01-01

Wild and domestic dark turkeys (Meleagris gallopavo) were fed experimental diets containing acorn (Quercus gambelli), ponderosa pine (Pinus ponderosa) seed, grasses, forbs, and arthropods. In fecal estimates of diet composition, acorn and ponderosa pine seed were underestimated and grass was overestimated....

Estimation of Kubo number and correlation length of fluctuating magnetic fields and pressure in BOUT + + edge pedestal collapse simulation

NASA Astrophysics Data System (ADS)

Kim, Jaewook; Lee, W.-J.; Jhang, Hogun; Kaang, H. H.; Ghim, Y.-C.

2017-10-01

Stochastic magnetic fields are thought to be as one of the possible mechanisms for anomalous transport of density, momentum and heat across the magnetic field lines. Kubo number and Chirikov parameter are quantifications of the stochasticity, and previous studies show that perpendicular transport strongly depends on the magnetic Kubo number (MKN). If MKN is smaller than one, diffusion process will follow Rechester-Rosenbluth model; whereas if it is larger than one, percolation theory dominates the diffusion process. Thus, estimation of Kubo number plays an important role to understand diffusion process caused by stochastic magnetic fields. However, spatially localized experimental measurement of fluctuating magnetic fields in a tokamak is difficult, and we attempt to estimate MKNs using BOUT + + simulation data with pedestal collapse. In addition, we calculate correlation length of fluctuating pressures and Chirikov parameters to investigate variation correlation lengths in the simulation. We, then, discuss how one may experimentally estimate MKNs.

Modification of the TASMIP x-ray spectral model for the simulation of microfocus x-ray sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sisniega, A.; Vaquero, J. J., E-mail: juanjose.vaquero@uc3m.es; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007

2014-01-15

Purpose: The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammography. However, most of these models cannot be used directly for modeling microfocus x-ray sources due to differences in inherent filtration, energy range and/or anode material. For this reason the authors propose in this work a new model for the simulation of microfocus spectra based on existing models for mammography and radiology, modifiedmore » to compensate for the effects of inherent filtration and energy range. Methods: The authors used the radiology and mammography versions of an existing empirical model [tungsten anode spectral model interpolating polynomials (TASMIP)] as the basis of the microfocus model. First, the authors estimated the inherent filtration included in the radiology model by comparing the shape of the spectra with spectra from the mammography model. Afterwards, the authors built a unified spectra dataset by combining both models and, finally, they estimated the parameters of the new version of TASMIP for microfocus sources by calibrating against experimental exposure data from a microfocus x-ray source. The model was validated by comparing estimated and experimental exposure and attenuation data for different attenuating materials and x-ray beam peak energy values, using two different x-ray tubes. Results: Inherent filtration for the radiology spectra from TASMIP was found to be equivalent to 1.68 mm Al, as compared to spectra obtained from the mammography model. To match the experimentally measured exposure data the combined dataset required to apply a negative filtration of about 0.21 mm Al and an anode roughness of 0.003 mm W. The validation of the model against real acquired data showed errors in exposure and attenuation in line with those reported for other models for radiology or mammography. Conclusions: A new version of the TASMIP model for the estimation of x-ray spectra in microfocus x-ray sources has been developed and validated experimentally. Similarly to other versions of TASMIP, the estimation of spectra is very simple, involving only the evaluation of polynomial expressions.« less

Transverse oscillations in plasma wakefield experiments at FACET

NASA Astrophysics Data System (ADS)

Adli, E.; Lindstrøm, C. A.; Allen, J.; Clarke, C. I.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Litos, M. D.; White, G. R.; Yakimenko, V.; An, W.; Clayton, C. E.; Marsh, K. A.; Mori, W. B.; Joshi, C.; Vafaei-Najafabadi, N.; Corde, S.; Lu, W.

2016-09-01

We study transverse effects in a plasma wakefield accelerator. Experimental data from FACET with asymmetry in the beam-plasma system is presented. Energy dependent centroid oscillations are observed on the accelerated part of the charge. The experimental results are compared to PIC simulations and theoretical estimates.

OPTIMIZING THE PRECISION OF TOXICITY THRESHOLD ESTIMATION USING A TWO-STAGE EXPERIMENTAL DESIGN

EPA Science Inventory

An important consideration for risk assessment is the existence of a threshold, i.e., the highest toxicant dose where the response is not distinguishable from background. We have developed methodology for finding an experimental design that optimizes the precision of threshold mo...

Theoretical and experimental investigation of supersonic aerodynamic characteristics of a twin-fuselage concept

NASA Technical Reports Server (NTRS)

Wood, R. M.; Miller, D. S.; Brentner, K. S.

1983-01-01

A theoretical and experimental investigation has been conducted to evaluate the fundamental supersonic aerodynamic characteristics of a generic twin-body model at a Mach number of 2.70. Results show that existing aerodynamic prediction methods are adequate for making preliminary aerodynamic estimates.

Comparison of laser anemometer measurements and theory in an annular turbine cascade with experimental accuracy determined by parameter estimation

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Seasholtz, R. G.

1982-01-01

Experimental measurements of the velocity components in the blade to blade (axial tangential) plane were obtained with an axial flow turbine stator passage and were compared with calculations from three turbomachinery computer programs. The theoretical results were calculated from a quasi three dimensional inviscid code, a three dimensional inviscid code, and a three dimensional viscous code. Parameter estimation techniques and a particle dynamics calculation were used to assess the accuracy of the laser measurements, which allow a rational basis for comparison of the experimenal and theoretical results. The general agreement of the experimental data with the results from the two inviscid computer codes indicates the usefulness of these calculation procedures for turbomachinery blading. The comparison with the viscous code, while generally reasonable, was not as good as for the inviscid codes.

Identifying the Oscillatory Mechanism of the Glucose Oxidase-Catalase Coupled Enzyme System.

PubMed

Muzika, František; Jurašek, Radovan; Schreiberová, Lenka; Radojković, Vuk; Schreiber, Igor

2017-10-12

We provide experimental evidence of periodic and aperiodic oscillations in an enzymatic system of glucose oxidase-catalase in a continuous-flow stirred reactor coupled by a membrane with a continuous-flow reservoir supplied with hydrogen peroxide. To describe such dynamics, we formulate a detailed mechanism based on partial results in the literature. Finally, we introduce a novel method for estimation of unknown kinetic parameters. The method is based on matching experimental data at an oscillatory instability with stoichiometric constraints of the mechanism formulated by applying the stability theory of reaction networks. This approach has been used to estimate rate coefficients in the catalase part of the mechanism. Remarkably, model simulations show good agreement with the observed oscillatory dynamics, including apparently chaotic intermittent behavior. Our method can be applied to any reaction system with an experimentally observable dynamical instability.

Comparison of the excretion of sodium and meglumine diatrizoate at urography with simulated compression: an experimental study in the rat.

PubMed

Owman, T

1981-07-01

In the experimental model in the rabbit the excretion of sodium and meglumine diatrizoate, respectively, have been compared. Urographic density which was estimated through renal pelvic volume as calculated according to previous experiments (Owman 1978; Owman & Olin 1980) and urinary iodine concentration, is suggested to be more accurate than mere determination of urine iodine concentration and diuresis when evaluating and comparing urographic contrast media experimentally. More reliable dose optima are probably found when calculating density rather than determining urine concentrations. Of the examined media in this investigation, the sodium salt of diatrizoate was not superior to the meglumine salt in dose ranges up to 320 mg I/kg body weight, while at higher doses sodium diatrizoate gave higher urinary iodine concentrations and higher estimated density.

Structure and energetics of Cr(CO)6 and Cr(CO)5

NASA Technical Reports Server (NTRS)

Barnes, Leslie A.; Liu, Bowen; Lindh, Roland

1993-01-01

The geometric structures and energetics of Cr(CO)6 and Cr(CO)5 are determined at the modified coupled-pair functional, single and double excitation coupled-cluster (CCSD), and CCSD(T) levels of theory. For Cr(CO)6, the structure and force constants for the totally symmetric representation are in good agreement with experimental data once basis set constants are taken into account. In the largest basis set at the CCSD(T) level of theory, the total binding energy of CR(CO)6 is estimated at around 140 kcal/mol, or about 86 percent of the experimental value. In contrast, the first bond energy of Cr(CO)6 is very well described at the CCSD(T) level of theory, with the best estimated value of 38 kcal/mol being within the experimental uncertainty.

Title I preliminary engineering for: A. S. E. F. solid waste to methane gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1976-01-01

An assignment to provide preliminary engineering of an Advanced System Experimental Facility for production of methane gas from urban solid waste by anaerobic digestion is documented. The experimental facility will be constructed on a now-existing solid waste shredding and landfill facility in Pompano Beach, Florida. Information is included on: general description of the project; justification of basic need; process design; preliminary drawings; outline specifications; preliminary estimate of cost; and time schedules for design and construction of accomplishment of design and construction. The preliminary cost estimate for the design and construction phases of the experimental program is $2,960,000, based on Dec.more » 1975 and Jan. 1976 costs. A time schedule of eight months to complete the Detailed Design, Equipment Procurement and the Award of Subcontracts is given.« less

Officer Career Development: Analytic Strategy Recommendations

DTIC Science & Technology

1989-07-01

model is perhaps better suited to experimental designs where investigators determine discrete values for each Xi and then randomly sample subjects into... experimental designs . New York: McGraw-Hill. ,Terlove, 4. (1971). Further evidence on the estimation of dynamic economic relations from a time series of...Cunningham. W. R., & Birren, 1. E. (1980). Age chsane in the factor Newseroade. I R., & Labouvie. E V. 1985) Experimental design in structure of

Damage Precursor Detection in Polymer Matrix Composites Using Novel Smart Composite Particles

DTIC Science & Technology

2016-09-20

during the deformation test. Good agreement was observed with experimental results : the intensity of fluorescence was found to be directly proportional to...agreement is observed with experimental results , for which the intensity of fluorescence was found to be directly proportional to the deformation. Epoxy...the estimated Tgs of both neat epoxy and the smart polymer were compared with the experimental results obtained by DSC. Unit cell preparation

Optimal experimental design for parameter estimation of a cell signaling model.

PubMed

Bandara, Samuel; Schlöder, Johannes P; Eils, Roland; Bock, Hans Georg; Meyer, Tobias

2009-11-01

Differential equation models that describe the dynamic changes of biochemical signaling states are important tools to understand cellular behavior. An essential task in building such representations is to infer the affinities, rate constants, and other parameters of a model from actual measurement data. However, intuitive measurement protocols often fail to generate data that restrict the range of possible parameter values. Here we utilized a numerical method to iteratively design optimal live-cell fluorescence microscopy experiments in order to reveal pharmacological and kinetic parameters of a phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) second messenger signaling process that is deregulated in many tumors. The experimental approach included the activation of endogenous phosphoinositide 3-kinase (PI3K) by chemically induced recruitment of a regulatory peptide, reversible inhibition of PI3K using a kinase inhibitor, and monitoring of the PI3K-mediated production of PIP(3) lipids using the pleckstrin homology (PH) domain of Akt. We found that an intuitively planned and established experimental protocol did not yield data from which relevant parameters could be inferred. Starting from a set of poorly defined model parameters derived from the intuitively planned experiment, we calculated concentration-time profiles for both the inducing and the inhibitory compound that would minimize the predicted uncertainty of parameter estimates. Two cycles of optimization and experimentation were sufficient to narrowly confine the model parameters, with the mean variance of estimates dropping more than sixty-fold. Thus, optimal experimental design proved to be a powerful strategy to minimize the number of experiments needed to infer biological parameters from a cell signaling assay.

Modal Damping Ratio and Optimal Elastic Moduli of Human Body Segments for Anthropometric Vibratory Model of Standing Subjects.

PubMed

Gupta, Manoj; Gupta, T C

2017-10-01

The present study aims to accurately estimate inertial, physical, and dynamic parameters of human body vibratory model consistent with physical structure of the human body that also replicates its dynamic response. A 13 degree-of-freedom (DOF) lumped parameter model for standing person subjected to support excitation is established. Model parameters are determined from anthropometric measurements, uniform mass density, elastic modulus of individual body segments, and modal damping ratios. Elastic moduli of ellipsoidal body segments are initially estimated by comparing stiffness of spring elements, calculated from a detailed scheme, and values available in literature for same. These values are further optimized by minimizing difference between theoretically calculated platform-to-head transmissibility ratio (TR) and experimental measurements. Modal damping ratios are estimated from experimental transmissibility response using two dominant peaks in the frequency range of 0-25 Hz. From comparison between dynamic response determined form modal analysis and experimental results, a set of elastic moduli for different segments of human body and a novel scheme to determine modal damping ratios from TR plots, are established. Acceptable match between transmissibility values calculated from the vibratory model and experimental measurements for 50th percentile U.S. male, except at very low frequencies, establishes the human body model developed. Also, reasonable agreement obtained between theoretical response curve and experimental response envelop for average Indian male, affirms the technique used for constructing vibratory model of a standing person. Present work attempts to develop effective technique for constructing subject specific damped vibratory model based on its physical measurements.

A joint-space numerical model of metabolic energy expenditure for human multibody dynamic system.

PubMed

Kim, Joo H; Roberts, Dustyn

2015-09-01

Metabolic energy expenditure (MEE) is a critical performance measure of human motion. In this study, a general joint-space numerical model of MEE is derived by integrating the laws of thermodynamics and principles of multibody system dynamics, which can evaluate MEE without the limitations inherent in experimental measurements (phase delays, steady state and task restrictions, and limited range of motion) or muscle-space models (complexities and indeterminacies from excessive DOFs, contacts and wrapping interactions, and reliance on in vitro parameters). Muscle energetic components are mapped to the joint space, in which the MEE model is formulated. A constrained multi-objective optimization algorithm is established to estimate the model parameters from experimental walking data also used for initial validation. The joint-space parameters estimated directly from active subjects provide reliable MEE estimates with a mean absolute error of 3.6 ± 3.6% relative to validation values, which can be used to evaluate MEE for complex non-periodic tasks that may not be experimentally verifiable. This model also enables real-time calculations of instantaneous MEE rate as a function of time for transient evaluations. Although experimental measurements may not be completely replaced by model evaluations, predicted quantities can be used as strong complements to increase reliability of the results and yield unique insights for various applications. Copyright © 2015 John Wiley & Sons, Ltd.

Assessment of reduced-order unscented Kalman filter for parameter identification in 1-dimensional blood flow models using experimental data.

PubMed

Caiazzo, A; Caforio, Federica; Montecinos, Gino; Muller, Lucas O; Blanco, Pablo J; Toro, Eluterio F

2016-10-25

This work presents a detailed investigation of a parameter estimation approach on the basis of the reduced-order unscented Kalman filter (ROUKF) in the context of 1-dimensional blood flow models. In particular, the main aims of this study are (1) to investigate the effects of using real measurements versus synthetic data for the estimation procedure (i.e., numerical results of the same in silico model, perturbed with noise) and (2) to identify potential difficulties and limitations of the approach in clinically realistic applications to assess the applicability of the filter to such setups. For these purposes, the present numerical study is based on a recently published in vitro model of the arterial network, for which experimental flow and pressure measurements are available at few selected locations. To mimic clinically relevant situations, we focus on the estimation of terminal resistances and arterial wall parameters related to vessel mechanics (Young's modulus and wall thickness) using few experimental observations (at most a single pressure or flow measurement per vessel). In all cases, we first perform a theoretical identifiability analysis on the basis of the generalized sensitivity function, comparing then the results owith the ROUKF, using either synthetic or experimental data, to results obtained using reference parameters and to available measurements. Copyright © 2016 John Wiley & Sons, Ltd.

A Strain-Based Method to Detect Tires' Loss of Grip and Estimate Lateral Friction Coefficient from Experimental Data by Fuzzy Logic for Intelligent Tire Development.

PubMed

Yunta, Jorge; Garcia-Pozuelo, Daniel; Diaz, Vicente; Olatunbosun, Oluremi

2018-02-06

Tires are a key sub-system of vehicles that have a big responsibility for comfort, fuel consumption and traffic safety. However, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or vehicle safety. The lack of information from the tire during driving gives cause for developing an intelligent tire. Therefore, the aim of the intelligent tire is to monitor tire working conditions in real-time, providing useful information to other systems and becoming an active system. In this paper, tire tread deformation is measured to provide a strong experimental base with different experiments and test results by means of a tire fitted with sensors. Tests under different working conditions such as vertical load or slip angle have been carried out with an indoor tire test rig. The experimental data analysis shows the strong relation that exists between lateral force and the maximum tensile and compressive strain peaks when the tire is not working at the limit of grip. In the last section, an estimation system from experimental data has been developed and implemented in Simulink to show the potential of strain sensors for developing intelligent tire systems, obtaining as major results a signal to detect tire's loss of grip and estimations of the lateral friction coefficient.

A Strain-Based Method to Detect Tires’ Loss of Grip and Estimate Lateral Friction Coefficient from Experimental Data by Fuzzy Logic for Intelligent Tire Development

PubMed Central

Garcia-Pozuelo, Daniel; Diaz, Vicente; Olatunbosun, Oluremi

2018-01-01

Tires are a key sub-system of vehicles that have a big responsibility for comfort, fuel consumption and traffic safety. However, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or vehicle safety. The lack of information from the tire during driving gives cause for developing an intelligent tire. Therefore, the aim of the intelligent tire is to monitor tire working conditions in real-time, providing useful information to other systems and becoming an active system. In this paper, tire tread deformation is measured to provide a strong experimental base with different experiments and test results by means of a tire fitted with sensors. Tests under different working conditions such as vertical load or slip angle have been carried out with an indoor tire test rig. The experimental data analysis shows the strong relation that exists between lateral force and the maximum tensile and compressive strain peaks when the tire is not working at the limit of grip. In the last section, an estimation system from experimental data has been developed and implemented in Simulink to show the potential of strain sensors for developing intelligent tire systems, obtaining as major results a signal to detect tire’s loss of grip and estimations of the lateral friction coefficient. PMID:29415513

Phase Helps Find Geometrically Optimal Gaits

NASA Astrophysics Data System (ADS)

Revzen, Shai; Hatton, Ross

Geometric motion planning describes motions of animals and machines governed by g ˙ = gA (q) q ˙ - a connection A (.) relating shape q and shape velocity q ˙ to body frame velocity g-1 g ˙ ∈ se (3) . Measuring the entire connection over a multidimensional q is often unfeasible with current experimental methods. We show how using a phase estimator can make tractable measuring the local structure of the connection surrounding a periodic motion q (φ) driven by a phase φ ∈S1 . This approach reduces the complexity of the estimation problem by a factor of dimq . The results suggest that phase estimation can be combined with geometric optimization into an iterative gait optimization algorithm usable on experimental systems, or alternatively, to allow the geometric optimality of an observed gait to be detected. ARO W911NF-14-1-0573, NSF 1462555.

Unbalanced and Minimal Point Equivalent Estimation Second-Order Split-Plot Designs

NASA Technical Reports Server (NTRS)

Parker, Peter A.; Kowalski, Scott M.; Vining, G. Geoffrey

2007-01-01

Restricting the randomization of hard-to-change factors in industrial experiments is often performed by employing a split-plot design structure. From an economic perspective, these designs minimize the experimental cost by reducing the number of resets of the hard-to- change factors. In this paper, unbalanced designs are considered for cases where the subplots are relatively expensive and the experimental apparatus accommodates an unequal number of runs per whole-plot. We provide construction methods for unbalanced second-order split- plot designs that possess the equivalence estimation optimality property, providing best linear unbiased estimates of the parameters; independent of the variance components. Unbalanced versions of the central composite and Box-Behnken designs are developed. For cases where the subplot cost approaches the whole-plot cost, minimal point designs are proposed and illustrated with a split-plot Notz design.

Discriminative Learning of Receptive Fields from Responses to Non-Gaussian Stimulus Ensembles

PubMed Central

Meyer, Arne F.; Diepenbrock, Jan-Philipp; Happel, Max F. K.; Ohl, Frank W.; Anemüller, Jörn

2014-01-01

Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and in settings where rapid adaptation is induced by experimental design. PMID:24699631

Discriminative learning of receptive fields from responses to non-Gaussian stimulus ensembles.

PubMed

Meyer, Arne F; Diepenbrock, Jan-Philipp; Happel, Max F K; Ohl, Frank W; Anemüller, Jörn

2014-01-01

Analysis of sensory neurons' processing characteristics requires simultaneous measurement of presented stimuli and concurrent spike responses. The functional transformation from high-dimensional stimulus space to the binary space of spike and non-spike responses is commonly described with linear-nonlinear models, whose linear filter component describes the neuron's receptive field. From a machine learning perspective, this corresponds to the binary classification problem of discriminating spike-eliciting from non-spike-eliciting stimulus examples. The classification-based receptive field (CbRF) estimation method proposed here adapts a linear large-margin classifier to optimally predict experimental stimulus-response data and subsequently interprets learned classifier weights as the neuron's receptive field filter. Computational learning theory provides a theoretical framework for learning from data and guarantees optimality in the sense that the risk of erroneously assigning a spike-eliciting stimulus example to the non-spike class (and vice versa) is minimized. Efficacy of the CbRF method is validated with simulations and for auditory spectro-temporal receptive field (STRF) estimation from experimental recordings in the auditory midbrain of Mongolian gerbils. Acoustic stimulation is performed with frequency-modulated tone complexes that mimic properties of natural stimuli, specifically non-Gaussian amplitude distribution and higher-order correlations. Results demonstrate that the proposed approach successfully identifies correct underlying STRFs, even in cases where second-order methods based on the spike-triggered average (STA) do not. Applied to small data samples, the method is shown to converge on smaller amounts of experimental recordings and with lower estimation variance than the generalized linear model and recent information theoretic methods. Thus, CbRF estimation may prove useful for investigation of neuronal processes in response to natural stimuli and in settings where rapid adaptation is induced by experimental design.

Estimation of hydrogen sulfide emission rates at several wastewater treatment plants through experimental concentration measurements and dispersion modeling.

PubMed

Llavador Colomer, Fernando; Espinós Morató, Héctor; Mantilla Iglesias, Enrique

2012-07-01

The management and operation of wastewater treatment plants (WWTP) usually involve the release into the atmosphere of malodorous substances with the potential to reduce the quality of life of people living nearby. In this type of facility, anaerobic degradation processes contribute to the generation of hydrogen sulfide (H2S), often at quite high concentrations; thus, the presence of this chemical compound in the atmosphere can be a good indicator of the occurrence and intensity of the olfactory impact in a specific area. The present paper describes the experimental and modelling work being carried out by CEAM-UMH in the surroundings of several wastewater treatment plants located in the Valencia Autonomous Community (Spain). This work has permitted the estimation of H2S emission rates at different WWTPs under different environmental and operating conditions. Our methodological approach for analyzing and describing the most relevant aspects of the olfactory impact consisted of several experimental campaigns involving intensive field measurements using passive samplers in the vicinity of several WWTPs, in combination with numerical simulation results from a diagnostic dispersion model. A meteorological tower at each WWTP provided the input values for the dispersion code, ensuring a good fit of the advective component and therefore more confidence in the modelled concentration field in response to environmental conditions. Then, comparisons between simulated and experimental H2S concentrations yielded estimates of the global emission rate for this substance at several WWTPs at different time periods. The results obtained show a certain degree of temporal and spatial (between-plant) variability (possibly due to both operational and environmental conditions). Nevertheless, and more importantly, the results show a high degree of uniformity in the estimates, which consistently stay within the same order of magnitude.

Estimation of surface soil moisture and roughness from multi-angular ASAR imagery in the Watershed Allied Telemetry Experimental Research (WATER)

NASA Astrophysics Data System (ADS)

Wang, S. G.; Li, X.; Han, X. J.; Jin, R.

2011-05-01

Radar remote sensing has demonstrated its applicability to the retrieval of basin-scale soil moisture. The mechanism of radar backscattering from soils is complicated and strongly influenced by surface roughness. Additionally, retrieval of soil moisture using AIEM (advanced integrated equation model)-like models is a classic example of underdetermined problem due to a lack of credible known soil roughness distributions at a regional scale. Characterization of this roughness is therefore crucial for an accurate derivation of soil moisture based on backscattering models. This study aims to simultaneously obtain surface roughness parameters (standard deviation of surface height σ and correlation length cl) along with soil moisture from multi-angular ASAR images by using a two-step retrieval scheme based on the AIEM. The method firstly used a semi-empirical relationship that relates the roughness slope, Zs (Zs = σ2/cl) and the difference in backscattering coefficient (Δσ) from two ASAR images acquired with different incidence angles. Meanwhile, by using an experimental statistical relationship between σ and cl, both these parameters can be estimated. Then, the deduced roughness parameters were used for the retrieval of soil moisture in association with the AIEM. An evaluation of the proposed method was performed in an experimental area in the middle stream of the Heihe River Basin, where the Watershed Allied Telemetry Experimental Research (WATER) was taken place. It is demonstrated that the proposed method is feasible to achieve reliable estimation of soil water content. The key challenge is the presence of vegetation cover, which significantly impacts the estimates of surface roughness and soil moisture.

Estimating loop length from CryoEM images at medium resolutions.

PubMed

McKnight, Andrew; Si, Dong; Al Nasr, Kamal; Chernikov, Andrey; Chrisochoides, Nikos; He, Jing

2013-01-01

De novo protein modeling approaches utilize 3-dimensional (3D) images derived from electron cryomicroscopy (CryoEM) experiments. The skeleton connecting two secondary structures such as α-helices represent the loop in the 3D image. The accuracy of the skeleton and of the detected secondary structures are critical in De novo modeling. It is important to measure the length along the skeleton accurately since the length can be used as a constraint in modeling the protein. We have developed a novel computational geometric approach to derive a simplified curve in order to estimate the loop length along the skeleton. The method was tested using fifty simulated density images of helix-loop-helix segments of atomic structures and eighteen experimentally derived density data from Electron Microscopy Data Bank (EMDB). The test using simulated density maps shows that it is possible to estimate within 0.5 Å of the expected length for 48 of the 50 cases. The experiments, involving eighteen experimentally derived CryoEM images, show that twelve cases have error within 2 Å. The tests using both simulated and experimentally derived images show that it is possible for our proposed method to estimate the loop length along the skeleton if the secondary structure elements, such as α-helices, can be detected accurately, and there is a continuous skeleton linking the α-helices.

Modeling animal movements using stochastic differential equations

Treesearch

Haiganoush K. Preisler; Alan A. Ager; Bruce K. Johnson; John G. Kie

2004-01-01

We describe the use of bivariate stochastic differential equations (SDE) for modeling movements of 216 radiocollared female Rocky Mountain elk at the Starkey Experimental Forest and Range in northeastern Oregon. Spatially and temporally explicit vector fields were estimated using approximating difference equations and nonparametric regression techniques. Estimated...

Field design factors affecting the precision of ryegrass forage yield estimation

USDA-ARS?s Scientific Manuscript database

Field-based agronomic and genetic research relies heavily on the data generated from field evaluations. Therefore, it is imperative to optimize the precision and accuracy of yield estimates in cultivar evaluation trials to make reliable selections. Experimental error in yield trials is sensitive to ...

The effects of ionic strength and organic matter on virus inactivation at low temperatures: general likelihood uncertainty estimation (GLUE) as an alternative to least-squares parameter optimization for the fitting of virus inactivation models

NASA Astrophysics Data System (ADS)

Mayotte, Jean-Marc; Grabs, Thomas; Sutliff-Johansson, Stacy; Bishop, Kevin

2017-06-01

This study examined how the inactivation of bacteriophage MS2 in water was affected by ionic strength (IS) and dissolved organic carbon (DOC) using static batch inactivation experiments at 4 °C conducted over a period of 2 months. Experimental conditions were characteristic of an operational managed aquifer recharge (MAR) scheme in Uppsala, Sweden. Experimental data were fit with constant and time-dependent inactivation models using two methods: (1) traditional linear and nonlinear least-squares techniques; and (2) a Monte-Carlo based parameter estimation technique called generalized likelihood uncertainty estimation (GLUE). The least-squares and GLUE methodologies gave very similar estimates of the model parameters and their uncertainty. This demonstrates that GLUE can be used as a viable alternative to traditional least-squares parameter estimation techniques for fitting of virus inactivation models. Results showed a slight increase in constant inactivation rates following an increase in the DOC concentrations, suggesting that the presence of organic carbon enhanced the inactivation of MS2. The experiment with a high IS and a low DOC was the only experiment which showed that MS2 inactivation may have been time-dependent. However, results from the GLUE methodology indicated that models of constant inactivation were able to describe all of the experiments. This suggested that inactivation time-series longer than 2 months were needed in order to provide concrete conclusions regarding the time-dependency of MS2 inactivation at 4 °C under these experimental conditions.

3D shape reconstruction of specular surfaces by using phase measuring deflectometry

NASA Astrophysics Data System (ADS)

Zhou, Tian; Chen, Kun; Wei, Haoyun; Li, Yan

2016-10-01

The existing estimation methods for recovering height information from surface gradient are mainly divided into Modal and Zonal techniques. Since specular surfaces used in the industry always have complex and large areas, considerations must be given to both the improvement of measurement accuracy and the acceleration of on-line processing speed, which beyond the capacity of existing estimations. Incorporating the Modal and Zonal approaches into a unifying scheme, we introduce an improved 3D shape reconstruction version of specular surfaces based on Phase Measuring Deflectometry in this paper. The Modal estimation is firstly implemented to derive the coarse height information of the measured surface as initial iteration values. Then the real shape can be recovered utilizing a modified Zonal wave-front reconstruction algorithm. By combining the advantages of Modal and Zonal estimations, the proposed method simultaneously achieves consistently high accuracy and dramatically rapid convergence. Moreover, the iterative process based on an advanced successive overrelaxation technique shows a consistent rejection of measurement errors, guaranteeing the stability and robustness in practical applications. Both simulation and experimentally measurement demonstrate the validity and efficiency of the proposed improved method. According to the experimental result, the computation time decreases approximately 74.92% in contrast to the Zonal estimation and the surface error is about 6.68 μm with reconstruction points of 391×529 pixels of an experimentally measured sphere mirror. In general, this method can be conducted with fast convergence speed and high accuracy, providing an efficient, stable and real-time approach for the shape reconstruction of specular surfaces in practical situations.

14 CFR 437.25 - Flight test plan.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Flight test plan. 437.25 Section 437.25... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Requirements to Obtain an Experimental Permit Flight Test Plan § 437.25 Flight test plan. An applicant must— (a) Describe any flight test program, including estimated...

14 CFR 437.25 - Flight test plan.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Flight test plan. 437.25 Section 437.25... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Requirements to Obtain an Experimental Permit Flight Test Plan § 437.25 Flight test plan. An applicant must— (a) Describe any flight test program, including estimated...

14 CFR 437.25 - Flight test plan.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Flight test plan. 437.25 Section 437.25... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Requirements to Obtain an Experimental Permit Flight Test Plan § 437.25 Flight test plan. An applicant must— (a) Describe any flight test program, including estimated...

THE USE OF NON-TUMOR DATA IN CANCER RISK ASSESSMENT: REFLECTIONS ON BENZENE, BUTADIENE AND VINYL CHLORIDE

EPA Science Inventory

1.0 Introduction. Quantitative estimation of human cancer risk from exposure to chemicals has traditionally been almost exclusively based on tumor incidence in experimental animals. While improvements in carcinogenicity testing in experimental animals (1,2) and structure-...

76 FR 78927 - Proposed Information Collection Activity; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... estimates of the effectiveness of the programs. This component will use an experimental design. Program... inform decisions related to future investments in this kind of programming as well as the design and operation of such services. To meet the objective of the study, experimental impact studies with...

Experimental Method Development for Estimating Solid-phase Diffusion Coefficients and Material/Air Partition Coefficients of SVOCs

EPA Science Inventory

The solid-phase diffusion coefficient (Dm) and material-air partition coefficient (Kma) are key parameters for characterizing the sources and transport of semivolatile organic compounds (SVOCs) in the indoor environment. In this work, a new experimental method was developed to es...

Essays on Policy Evaluation with Endogenous Adoption

ERIC Educational Resources Information Center

Gentile, Elisabetta

2011-01-01

Over the last decade, experimental and quasi-experimental methods have been favored by researchers in empirical economics, as they provide unbiased causal estimates. However, when implementing a program, it is often not possible to randomly assign subjects to treatment, leading to a possible endogeneity bias. This dissertation consists of two…

EXPERIMENTAL METHODOLOGIES AND PRELIMINARY TRANSFER FACTOR DATA FOR ESTIMATION OF DERMAL EXPOSURES TO PARTICLES

EPA Science Inventory

Developmental efforts and experimental data are described that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin. Methods were developed that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate ...

Convergence in parameters and predictions using computational experimental design.

PubMed

Hagen, David R; White, Jacob K; Tidor, Bruce

2013-08-06

Typically, biological models fitted to experimental data suffer from significant parameter uncertainty, which can lead to inaccurate or uncertain predictions. One school of thought holds that accurate estimation of the true parameters of a biological system is inherently problematic. Recent work, however, suggests that optimal experimental design techniques can select sets of experiments whose members probe complementary aspects of a biochemical network that together can account for its full behaviour. Here, we implemented an experimental design approach for selecting sets of experiments that constrain parameter uncertainty. We demonstrated with a model of the epidermal growth factor-nerve growth factor pathway that, after synthetically performing a handful of optimal experiments, the uncertainty in all 48 parameters converged below 10 per cent. Furthermore, the fitted parameters converged to their true values with a small error consistent with the residual uncertainty. When untested experimental conditions were simulated with the fitted models, the predicted species concentrations converged to their true values with errors that were consistent with the residual uncertainty. This paper suggests that accurate parameter estimation is achievable with complementary experiments specifically designed for the task, and that the resulting parametrized models are capable of accurate predictions.

Two biased estimation techniques in linear regression: Application to aircraft

NASA Technical Reports Server (NTRS)

Klein, Vladislav

1988-01-01

Several ways for detection and assessment of collinearity in measured data are discussed. Because data collinearity usually results in poor least squares estimates, two estimation techniques which can limit a damaging effect of collinearity are presented. These two techniques, the principal components regression and mixed estimation, belong to a class of biased estimation techniques. Detection and assessment of data collinearity and the two biased estimation techniques are demonstrated in two examples using flight test data from longitudinal maneuvers of an experimental aircraft. The eigensystem analysis and parameter variance decomposition appeared to be a promising tool for collinearity evaluation. The biased estimators had far better accuracy than the results from the ordinary least squares technique.

Mortality estimation from carcass searches using the R-package carcass: a tutorial

USGS Publications Warehouse

Korner-Nievergelt, Fränzi; Behr, Oliver; Brinkmann, Robert; Etterson, Matthew A.; Huso, Manuela M. P.; Dalthorp, Daniel; Korner-Nievergelt, Pius; Roth, Tobias; Niermann, Ivo

2015-01-01

This article is a tutorial for the R-package carcass. It starts with a short overview of common methods used to estimate mortality based on carcass searches. Then, it guides step by step through a simple example. First, the proportion of animals that fall into the search area is estimated. Second, carcass persistence time is estimated based on experimental data. Third, searcher efficiency is estimated. Fourth, these three estimated parameters are combined to obtain the probability that an animal killed is found by an observer. Finally, this probability is used together with the observed number of carcasses found to obtain an estimate for the total number of killed animals together with a credible interval.

Methods for the accurate estimation of confidence intervals on protein folding ϕ-values

PubMed Central

Ruczinski, Ingo; Sosnick, Tobin R.; Plaxco, Kevin W.

2006-01-01

ϕ-Values provide an important benchmark for the comparison of experimental protein folding studies to computer simulations and theories of the folding process. Despite the growing importance of ϕ measurements, however, formulas to quantify the precision with which ϕ is measured have seen little significant discussion. Moreover, a commonly employed method for the determination of standard errors on ϕ estimates assumes that estimates of the changes in free energy of the transition and folded states are independent. Here we demonstrate that this assumption is usually incorrect and that this typically leads to the underestimation of ϕ precision. We derive an analytical expression for the precision of ϕ estimates (assuming linear chevron behavior) that explicitly takes this dependence into account. We also describe an alternative method that implicitly corrects for the effect. By simulating experimental chevron data, we show that both methods accurately estimate ϕ confidence intervals. We also explore the effects of the commonly employed techniques of calculating ϕ from kinetics estimated at non-zero denaturant concentrations and via the assumption of parallel chevron arms. We find that these approaches can produce significantly different estimates for ϕ (again, even for truly linear chevron behavior), indicating that they are not equivalent, interchangeable measures of transition state structure. Lastly, we describe a Web-based implementation of the above algorithms for general use by the protein folding community. PMID:17008714

Estimates of the values of elk in the Blue Mountains of Oregon and Washington: evidence from existing literature.

Treesearch

N.A. Bolon

1994-01-01

Existing literature was used to estimate the economic value of elk to hunters and wildlife watchers, and the economic impact on personal income to local communities in the Blue Mountains (Blues) of Oregon and Washington. An annual survey of hunters at the Starkey Experimental Forest and Range provided data for estimated elk hunting values and expenditure impacts. The...

Flight-path estimation in passive low-altitude flight by visual cues

NASA Technical Reports Server (NTRS)

Grunwald, Arthur J.; Kohn, S.

1993-01-01

A series of experiments was conducted, in which subjects had to estimate the flight path while passively being flown in straight or in curved motion over several types of nominally flat, textured terrain. Three computer-generated terrain types were investigated: (1) a random 'pole' field, (2) a flat field consisting of random rectangular patches, and (3) a field of random parallelepipeds. Experimental parameters were the velocity-to-height (V/h) ratio, the viewing distance, and the terrain type. Furthermore, the effect of obscuring parts of the visual field was investigated. Assumptions were made about the basic visual-field information by analyzing the pattern of line-of-sight (LOS) rate vectors in the visual field. The experimental results support these assumptions and show that, for both a straight as well as a curved flight path, the estimation accuracy and estimation times improve with the V/h ratio. Error scores for the curved flight path are found to be about 3 deg in visual angle higher than for the straight flight path, and the sensitivity to the V/h ratio is found to be considerably larger. For the straight motion, the flight path could be estimated successfully from local areas in the far field. Curved flight-path estimates have to rely on the entire LOS rate pattern.

The investigation and implementation of real-time face pose and direction estimation on mobile computing devices

NASA Astrophysics Data System (ADS)

Fu, Deqian; Gao, Lisheng; Jhang, Seong Tae

2012-04-01

The mobile computing device has many limitations, such as relative small user interface and slow computing speed. Usually, augmented reality requires face pose estimation can be used as a HCI and entertainment tool. As far as the realtime implementation of head pose estimation on relatively resource limited mobile platforms is concerned, it is required to face different constraints while leaving enough face pose estimation accuracy. The proposed face pose estimation method met this objective. Experimental results running on a testing Android mobile device delivered satisfactory performing results in the real-time and accurately.

USE OF EXPOSURE RELATED DOSE ESTIMATING MODEL ( ERDEM ) TO CONSTRUCT A PBPK /MODEL FOR CARBOFURAN WITH THE REPORTED EXPERIMENTAL DATA IN THE RAT

EPA Science Inventory

To better understand the relationships among carbofuran exposure, dose, and effects, a physiologically-based pharmacokinetic and pharmacodynamic (PBPK/PD) model was developed for the rat using the Exposure Related Dose Estimating Model (ERDEM) framework.

Sweep Width Estimation for Ground Search and Rescue

DTIC Science & Technology

2004-12-30

Develop data compatible with search planning and POD estimation methods that are de- signed to use sweep width data. An experimental...important for Park Rangers and man- trackers . Search experience was expected to be a significant correction factor. However, the re- sults indicate...41 4.1.1 Signing In

Independent Peer Evaluation of the Large Area Crop Inventory Experiment (LACIE): The LACIE Symposium

NASA Technical Reports Server (NTRS)

1978-01-01

Yield models and crop estimate accuracy are discussed within the Large Area Crop Inventory Experiment. The wheat yield estimates in the United States, Canada, and U.S.S.R. are emphasized. Experimental results design, system implementation, data processing systems, and applications were considered.

39 CFR 3050.21 - Content of the Postal Service's section 3652 report.

Code of Federal Regulations, 2011 CFR

2011-07-01

... competitive advantage for the Postal Service or any mailer. (i) For each nonpostal service, estimate its costs... unreasonable. (g) For each competitive negotiated service agreement: (1) Identify its rates and service... and by competitive product group; (2) Estimate the quality of service of each individual experimental...

Comparison of standing volume estimates using optical dendrometers

Treesearch

Neil A. Clark; Stanley J. Zarnoch; Alexander Clark; Gregory A. Reams

2001-01-01

This study compared height and diameter measurements and volume estimates on 20 hardwood and 20 softwood stems using traditional optical dendrometers, an experimental camera instrument, and mechanical calipers. Multiple comparison tests showed significant differences among the means for lower stem diameters when the camera was used. There were no significant...

Comparison of Standing Volume Estimates Using Optical Dendrometers

Treesearch

Neil A. Clark; Stanley J. Zarnoch; Alexander Clark; Gregory A. Reams

2001-01-01

This study compared height and diameter measurements and volume estimates on 20 hardwood and 20 softwood stems using traditional optical dendrometers, an experimental camera instrument, and mechanical calipers. Multiple comparison tests showed significant differences among the means for lower stem diameters when the camera was used. There were no significant...

Measuring landscape esthetics: the scenic beauty estimation method

Treesearch

Terry C. Daniel; Ron S. Boster

1976-01-01

The Scenic Beauty Estimation Method (SBE) provides quantitative measures of esthetic preferences for alternative wildland management systems. Extensive experimentation and testing with user, interest, and professional groups validated the method. SBE shows promise as an efficient and objective means for assessing the scenic beauty of public forests and wildlands, and...

SPECIFYING PHYSIOLOGICAL PARAMETERS FOR THE KINETICS OF INHALED TOLUENE IN RATS PERFORMING THE VISUAL SIGNAL DETECTION TASK (SDT).

EPA Science Inventory

A physiologically-based pharmacokinetic (PBPK) model is being developed to estimate the dosimetry of toluene in rats inhaling the VOC under various experimental conditions. The effects of physical activity are currently being estimated utilizing a three-step process. First, we d...

Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods

EPA Science Inventory

Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

Experimental setup for the measurement of induction motor cage currents

NASA Astrophysics Data System (ADS)

Bottauscio, Oriano; Chiampi, Mario; Donadio, Lorenzo; Zucca, Mauro

2005-04-01

An experimental setup for measurement of the currents flowing in the rotor bars of induction motors during synchronous no-load tests is described in the paper. The experimental verification of the high-frequency phenomena in the rotor cage is fundamental for a deep insight of the additional loss estimation by numerical methods. The attention is mainly focused on the analysis and design of the transducers developed for the cage current measurement.

A new device to estimate abundance of moist-soil plant seeds

USGS Publications Warehouse

Penny, E.J.; Kaminski, R.M.; Reinecke, K.J.

2006-01-01

Methods to sample the abundance of moist-soil seeds efficiently and accurately are critical for evaluating management practices and determining food availability. We adapted a portable, gasoline-powered vacuum to estimate abundance of seeds on the surface of a moist-soil wetland in east-central Mississippi and evaluated the sampler by simulating conditions that researchers and managers may experience when sampling moist-soil areas for seeds. We measured the percent recovery of known masses of seeds by the vacuum sampler in relation to 4 experimentally controlled factors (i.e., seed-size class, sample mass, soil moisture class, and vacuum time) with 2-4 levels per factor. We also measured processing time of samples in the laboratory. Across all experimental factors, seed recovery averaged 88.4% and varied little (CV = 0.68%, n = 474). Overall, mean time to process a sample was 30.3 ? 2.5 min (SE, n = 417). Our estimate of seed recovery rate (88%) may be used to adjust estimates for incomplete seed recovery, or project-specific correction factors may be developed by investigators. Our device was effective for estimating surface abundance of moist-soil plant seeds after dehiscence and before habitats were flooded.

Determining the composition of gold nanoparticles: a compilation of shapes, sizes, and calculations using geometric considerations.

PubMed

Mori, Taizo; Hegmann, Torsten

2016-01-01

Size, shape, overall composition, and surface functionality largely determine the properties and applications of metal nanoparticles. Aside from well-defined metal clusters, their composition is often estimated assuming a quasi-spherical shape of the nanoparticle core. With decreasing diameter of the assumed circumscribed sphere, particularly in the range of only a few nanometers, the estimated nanoparticle composition increasingly deviates from the real composition, leading to significant discrepancies between anticipated and experimentally observed composition, properties, and characteristics. We here assembled a compendium of tables, models, and equations for thiol-protected gold nanoparticles that will allow experimental scientists to more accurately estimate the composition of their gold nanoparticles using TEM image analysis data. The estimates obtained from following the routines described here will then serve as a guide for further analytical characterization of as-synthesized gold nanoparticles by other bulk (thermal, structural, chemical, and compositional) and surface characterization techniques. While the tables, models, and equations are dedicated to gold nanoparticles, the composition of other metal nanoparticle cores with face-centered cubic lattices can easily be estimated simply by substituting the value for the radius of the metal atom of interest.

Efficient implementation of a real-time estimation system for thalamocortical hidden Parkinsonian properties

NASA Astrophysics Data System (ADS)

Yang, Shuangming; Deng, Bin; Wang, Jiang; Li, Huiyan; Liu, Chen; Fietkiewicz, Chris; Loparo, Kenneth A.

2017-01-01

Real-time estimation of dynamical characteristics of thalamocortical cells, such as dynamics of ion channels and membrane potentials, is useful and essential in the study of the thalamus in Parkinsonian state. However, measuring the dynamical properties of ion channels is extremely challenging experimentally and even impossible in clinical applications. This paper presents and evaluates a real-time estimation system for thalamocortical hidden properties. For the sake of efficiency, we use a field programmable gate array for strictly hardware-based computation and algorithm optimization. In the proposed system, the FPGA-based unscented Kalman filter is implemented into a conductance-based TC neuron model. Since the complexity of TC neuron model restrains its hardware implementation in parallel structure, a cost efficient model is proposed to reduce the resource cost while retaining the relevant ionic dynamics. Experimental results demonstrate the real-time capability to estimate thalamocortical hidden properties with high precision under both normal and Parkinsonian states. While it is applied to estimate the hidden properties of the thalamus and explore the mechanism of the Parkinsonian state, the proposed method can be useful in the dynamic clamp technique of the electrophysiological experiments, the neural control engineering and brain-machine interface studies.

Nonparametric estimates of drift and diffusion profiles via Fokker-Planck algebra.

PubMed

Lund, Steven P; Hubbard, Joseph B; Halter, Michael

2014-11-06

Diffusion processes superimposed upon deterministic motion play a key role in understanding and controlling the transport of matter, energy, momentum, and even information in physics, chemistry, material science, biology, and communications technology. Given functions defining these random and deterministic components, the Fokker-Planck (FP) equation is often used to model these diffusive systems. Many methods exist for estimating the drift and diffusion profiles from one or more identifiable diffusive trajectories; however, when many identical entities diffuse simultaneously, it may not be possible to identify individual trajectories. Here we present a method capable of simultaneously providing nonparametric estimates for both drift and diffusion profiles from evolving density profiles, requiring only the validity of Langevin/FP dynamics. This algebraic FP manipulation provides a flexible and robust framework for estimating stationary drift and diffusion coefficient profiles, is not based on fluctuation theory or solved diffusion equations, and may facilitate predictions for many experimental systems. We illustrate this approach on experimental data obtained from a model lipid bilayer system exhibiting free diffusion and electric field induced drift. The wide range over which this approach provides accurate estimates for drift and diffusion profiles is demonstrated through simulation.

Comparison of linear and non-linear method in estimating the sorption isotherm parameters for safranin onto activated carbon.

PubMed

Kumar, K Vasanth; Sivanesan, S

2005-08-31

Comparison analysis of linear least square method and non-linear method for estimating the isotherm parameters was made using the experimental equilibrium data of safranin onto activated carbon at two different solution temperatures 305 and 313 K. Equilibrium data were fitted to Freundlich, Langmuir and Redlich-Peterson isotherm equations. All the three isotherm equations showed a better fit to the experimental equilibrium data. The results showed that non-linear method could be a better way to obtain the isotherm parameters. Redlich-Peterson isotherm is a special case of Langmuir isotherm when the Redlich-Peterson isotherm constant g was unity.

Measurements of surface-pressure fluctuations on the XB-70 airplane at local Mach numbers up to 2.45

NASA Technical Reports Server (NTRS)

Lewis, T. L.; Dods, J. B., Jr.; Hanly, R. D.

1973-01-01

Measurements of surface-pressure fluctuations were made at two locations on the XB-70 airplane for nine flight-test conditions encompassing a local Mach number range from 0.35 to 2.45. These measurements are presented in the form of estimated power spectral densities, coherence functions, and narrow-band-convection velocities. The estimated power spectral densities compared favorably with wind-tunnel data obtained by other experimenters. The coherence function and convection velocity data supported conclusions by other experimenters that low-frequency surface-pressure fluctuations consist of small-scale turbulence components with low convection velocity.

Estimation of the object orientation and location with the use of MEMS sensors

NASA Astrophysics Data System (ADS)

Sawicki, Aleksander; Walendziuk, Wojciech; Idzkowski, Adam

2015-09-01

The article presents the implementation of the estimation algorithms of orientation in 3D space and the displacement of an object in a 2D space. Moreover, a general orientation storage methods using Euler angles, quaternion and rotation matrix are presented. The experimental part presents the results of the complementary filter implementation. In the study experimental microprocessor module based on STM32f4 Discovery system and myRIO hardware platform equipped with FPGA were used. The attempt to track an object in two-dimensional space, which are showed in the final part of this article, were made with the use of the equipment mentioned above.

Experimental and calculative estimation of femtosecond laser induced-impulsive force in culture medium solution with motion analysis of polymer micro-beads

NASA Astrophysics Data System (ADS)

Yamakawa, Takeshi; Maruyama, Akihiro; Uedan, Hirohisa; Iino, Takanori; Hosokawa, Yoichiroh

2015-03-01

A new methodology to estimate the dynamics of femtosecond laser-induced impulsive force generated into water under microscope was developed. In this method, the position shift of the bead in water before and after the femtosecond laser irradiation was investigated experimentally and compared with motion equation assuming stress wave propagation with expansion and collapse the cavitation bubble. In the process of the comparison, parameters of force and time of the stress wave were determined. From these results, dynamics of propagations of shock and stress waves, cavitation bubble generation, and these actions to micro-objects were speculated.

New infrastructure for studies of transmutation and fast systems concepts

NASA Astrophysics Data System (ADS)

Panza, Fabio; Firpo, Gabriele; Lomonaco, Guglielmo; Osipenko, Mikhail; Ricco, Giovanni; Ripani, Marco; Saracco, Paolo; Viberti, Carlo Maria

2017-09-01

In this work we report initial studies on a low power Accelerator-Driven System as a possible experimental facility for the measurement of relevant integral nuclear quantities. In particular, we performed Monte Carlo simulations of minor actinides and fission products irradiation and estimated the fission rate within fission chambers in the reactor core and the reflector, in order to evaluate the transmutation rates and the measurement sensitivity. We also performed a photo-peak analysis of available experimental data from a research reactor, in order to estimate the expected sensitivity of this analysis method on the irradiation of samples in the ADS considered.

A low power ADS for transmutation studies in fast systems

NASA Astrophysics Data System (ADS)

Panza, Fabio; Firpo, Gabriele; Lomonaco, Guglielmo; Osipenko, Mikhail; Ricco, Giovanni; Ripani, Marco; Saracco, Paolo; Viberti, Carlo Maria

2017-12-01

In this work, we report studies on a fast low power accelerator driven system model as a possible experimental facility, focusing on its capabilities in terms of measurement of relevant integral nuclear quantities. In particular, we performed Monte Carlo simulations of minor actinides and fission products irradiation and estimated the fission rate within fission chambers in the reactor core and the reflector, in order to evaluate the transmutation rates and the measurement sensitivity. We also performed a photo-peak analysis of available experimental data from a research reactor, in order to estimate the expected sensitivity of this analysis method on the irradiation of samples in the ADS considered.

Parameter Estimation for Viscoplastic Material Modeling

NASA Technical Reports Server (NTRS)

Saleeb, Atef F.; Gendy, Atef S.; Wilt, Thomas E.

1997-01-01

A key ingredient in the design of engineering components and structures under general thermomechanical loading is the use of mathematical constitutive models (e.g. in finite element analysis) capable of accurate representation of short and long term stress/deformation responses. In addition to the ever-increasing complexity of recent viscoplastic models of this type, they often also require a large number of material constants to describe a host of (anticipated) physical phenomena and complicated deformation mechanisms. In turn, the experimental characterization of these material parameters constitutes the major factor in the successful and effective utilization of any given constitutive model; i.e., the problem of constitutive parameter estimation from experimental measurements.

Laser activation of a nutrient medium and antibiotic solutions and its estimation by of bacteria growth dynamics

NASA Astrophysics Data System (ADS)

Malov, Alexander N.; Neupokoeva, Anna V.; Kokorina, Lubov A.; Simonova, Elena V.

2016-11-01

A laser photomodifacation of nutrient mediums and antibiotics results at the microbiological supervision of bacteria colonies growth are discussed. It is experimentally shown, that on the irradiated media there is a delay of bacterial colonies growth number. Influence of laser radiation on activity of an antibiotic also is experimentally studied. It is revealed, that laser photomodifacation increases antimicrobic activity of a preparation. The mechanism of biological solutions activation is connected with the phenomenon laser nanoclusterization. Parameters of bacteria growth bacteria growth dynamics allow to numerically estimate degree of laser activation of nutrient mediums and pharmaceutical preparations.

A new approach to estimate the geometrical factors, solid angle approximation, geometrical efficiency and their use in basic interaction cross section measurements

NASA Astrophysics Data System (ADS)

Rao, D. V.; Cesareo, R.; Brunetti, A.; Gigante, G. E.; Takeda, T.; Itai, Y.; Akatsuka, T.

2002-10-01

A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic Kα radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work.

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE PAGES

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien; ...

2017-06-15

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

On Patarin's Attack against the lIC Scheme

NASA Astrophysics Data System (ADS)

Ogura, Naoki; Uchiyama, Shigenori

In 2007, Ding et al. proposed an attractive scheme, which is called the l-Invertible Cycles (lIC) scheme. lIC is one of the most efficient multivariate public-key cryptosystems (MPKC); these schemes would be suitable for using under limited computational resources. In 2008, an efficient attack against lIC using Gröbner basis algorithms was proposed by Fouque et al. However, they only estimated the complexity of their attack based on their experimental results. On the other hand, Patarin had proposed an efficient attack against some multivariate public-key cryptosystems. We call this attack Patarin's attack. The complexity of Patarin's attack can be estimated by finding relations corresponding to each scheme. In this paper, we propose an another practical attack against the lIC encryption/signature scheme. We estimate the complexity of our attack (not experimentally) by adapting Patarin's attack. The attack can be also applied to the lIC- scheme. Moreover, we show some experimental results of a practical attack against the lIC/lIC- schemes. This is the first implementation of both our proposed attack and an attack based on Gröbner basis algorithm for the even case, that is, a parameter l is even.

Experimental approach for thermal parameters estimation during glass forming process

NASA Astrophysics Data System (ADS)

Abdulhay, B.; Bourouga, B.; Alzetto, F.; Challita, C.

2016-10-01

In this paper, an experimental device designed and developedto estimate thermal conditions at the Glass / piston contact interface is presented. This deviceis made of two parts: the upper part contains the piston made of metal and a heating device to raise the temperature of the piston up to 500 °C. The lower part is composed of a lead crucible and a glass sample. The assembly is provided with a heating system, an induction furnace of 6 kW for heating the glass up to 950 °C.The developed experimental procedure has permitted in a previous published study to estimate the Thermal Contact ResistanceTCR using the inverse technique developed by Beck [1]. The semi-transparent character of the glass has been taken into account by an additional radiative heat flux and an equivalent thermal conductivity. After the set-up tests, reproducibility experiments for a specific contact pressure have been carried outwith a maximum dispersion that doesn't exceed 6%. Then, experiments under different conditions for a specific glass forming process regarding the application (Packaging, Buildings and Automobile) were carried out. The objective is to determine, experimentallyfor each application,the typical conditions capable to minimize the glass temperature loss during the glass forming process.

Optimization of planar PIV-based pressure estimates in laminar and turbulent wakes

NASA Astrophysics Data System (ADS)

McClure, Jeffrey; Yarusevych, Serhiy

2017-05-01

The performance of four pressure estimation techniques using Eulerian material acceleration estimates from planar, two-component Particle Image Velocimetry (PIV) data were evaluated in a bluff body wake. To allow for the ground truth comparison of the pressure estimates, direct numerical simulations of flow over a circular cylinder were used to obtain synthetic velocity fields. Direct numerical simulations were performed for Re_D = 100, 300, and 1575, spanning laminar, transitional, and turbulent wake regimes, respectively. A parametric study encompassing a range of temporal and spatial resolutions was performed for each Re_D. The effect of random noise typical of experimental velocity measurements was also evaluated. The results identified optimal temporal and spatial resolutions that minimize the propagation of random and truncation errors to the pressure field estimates. A model derived from linear error propagation through the material acceleration central difference estimators was developed to predict these optima, and showed good agreement with the results from common pressure estimation techniques. The results of the model are also shown to provide acceptable first-order approximations for sampling parameters that reduce error propagation when Lagrangian estimations of material acceleration are employed. For pressure integration based on planar PIV, the effect of flow three-dimensionality was also quantified, and shown to be most pronounced at higher Reynolds numbers downstream of the vortex formation region, where dominant vortices undergo substantial three-dimensional deformations. The results of the present study provide a priori recommendations for the use of pressure estimation techniques from experimental PIV measurements in vortex dominated laminar and turbulent wake flows.

A Simplified Approach to Cloud Masking with VIIRS in the S-NPP/JPSS Era

NASA Technical Reports Server (NTRS)

Jedlovec, Gary J.; Lafontaine, Frank J.

2014-01-01

The quantitative detection of clouds in satellite imagery has a number of important applications in weather analysis. The proper interpretation of satellite imagery for improved situational awareness depends on knowing where the clouds are at all times of the day. Additionally, many products derived from infrared measurements need accurate cloud information to mask out regions where retrieval of geophysical parameters in the atmosphere or on the surface are not possible. Thus, the accurate detection of the presence of clouds in satellite imagery on a global basis is important to the product developers and the operational weather community to support their decision-making process. This abstract describes an application of a two-channel bispectral composite threshold (BCT) approach applied to VIIRS imagery. The simplified BCT approach uses only the 10.76 and 3.75 micrometer spectral channels in two spectral tests; a straightforward infrared threshold test with the longwave channel and a shortwave minus longwave channel difference test. The key to the success of this approach as demonstrated in past applications to GOES and MODIS data is the generation of temporally and spatially dependent thresholds used in the tests from a previous number of days at similar observations to the current data. The presentation will present an overview of the approach and intercomparison results with other satellites, methods, and against verification data.

Phase Coupling Between Spectral Components of Collapsing Langmuir Solitons in Solar Type III Radio Bursts

NASA Technical Reports Server (NTRS)

Thejappa, G.; MacDowall, R. J.; Bergamo, M.

2012-01-01

We present the high time resolution observations of one of the Langmuir wave packets obtained in the source region of a solar type III radio burst. This wave packet satisfies the threshold condition of the supersonic modulational instability, as well as the criterion of a collapsing Langmuir soliton, i.e., the spatial scale derived from its peak intensity is less than that derived from its short time scale. The spectrum of t his wave packet contains an intense spectral peak at local electron plasma frequency, f(sub pe) and relatively weaker peaks at 2f(sub pe) and 3f(sub pe). We apply the wavelet based bispectral analysis technique on this wave packet and compute the bicoherence between its spectral components. It is found that the bicoherence exhibits two peaks at (approximately f(sub pe), approximately f(sub pe)) and (approximately f(sub pe) approximately 2f(sub pe)), which strongly suggest that the spectral peak at 2f(sub pe) probably corresponds to the second harmonic radio emission, generated as a result of the merging of antiparallel propagating Langmuir waves trapped in the collapsing Langmuir soliton, and, the spectral peak at 3f(sub pe) probably corresponds to the third harmonic radio emission, generated as a result of merging of a trapped Langmuir wave and a second harmonic electromagnetic wave.