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1

Electrocardiogram voltage attenuation and shortening of the duration of P-waves, QRS complexes, and QT intervals  

PubMed Central

Multiple pathologies in concert may lead to attenuation of the electrocardiogram (ECG) voltage. A case of a patient illustrating the above is presented, who showed marked attenuation of the ECG voltage. Automated values of the amplitude of the ECG QRS complexes, P-waves, and T-waves (in mm), duration of the QRS complexes, P-waves, and QT intervals (in ms), in 2 ECGs were compared. The patient was a 64-year-old woman who developed in the setting of a fatal illness, pleural and pericardial effusions, pneumomediastinum, pneumoperitoneum, subcutaneous emphysema in the neck and chest, peripheral edema with weight gain of 43.4 lbs, marked hypoalbuminemia, abnormal liver tests, and renal failure. All the above pathologies led to a marked attenuation of the ECG voltage, and shortening of the mean P-wave, QRS complexes, and QTc interval durations. The postulated mechanism of the observed ECG phenomena is discussed.

Madias, John E.

2013-01-01

2

[Wide QRS complex tachycardia: an old and new problem].  

PubMed

The correct diagnosis of wide QRS complex tachycardia is an old problem, but it is still a new problem since no simple approach aimed at solving it is up to now available, despite the amount of research devoted to this topic. A wide QRS tachycardia can be: 1) ventricular tachycardia; 2) supraventricular tachycardia with bundle branch block that may be either preexisting or due to aberrant conduction, namely tachycardia-dependent; a further possibility is the effect of antiarrhythmic drugs, which slow down intraventricular conduction, resulting in marked QRS complex widening; 3) supraventricular tachycardia with conduction of impulses to the ventricles over an accessory pathway (preexcited tachycardia). The origin of a wide QRS complex tachycardia can be reliably identified using a "holistic" approach, namely taking into account all of the available items: no single criterion, thus, is able to provide a simple and quick solution to the problem in all cases. The electrocardiographic signs are, without any exception, suggestive of ectopy, namely ventricular origin of the impulses; supraventricular tachycardia with aberrant conduction may be diagnosed only by excluding all of the items favoring ectopy. The classic diagnostic criteria include: 1) atrio-ventricular dissociation, characterized by absence of any relationship between QRS complexes and P waves; this phenomenon is at times immediately recognizable but more often can be discovered only by means of a detailed analysis of the tracing; 2) second degree ventriculo-atrial block, characterized by a relationship between QRS complexes and P waves, but with more ventricular complexes than P waves; 3) fusion and/or capture beats; 4) concordant precordial pattern, a sign that can be also expressed as absence of RS (or even rs, Rs, rS) complexes in the precordial leads; 5) an interval > 100 ms from the beginning of the QRS complex to the nadir of S wave in any precordial lead. Vagal maneuvers and analysis of previous ECGs recorded during sinus rhythm, if available, can provide further keys to the diagnosis. Some criteria proposed in the past, such as QRS axis or ventricular complex duration, are nowadays no longer considered; in addition, it has been demonstrated that items such as age, hemodynamic status, heart rate and regularity of R-R intervals may be misleading and should not be taken into account. Analysis of QRS configuration in leads V1 and V6 is a keystone in distinguishing the origin of wide QRS tachycardia: diagnostic criteria rely upon the assumption that aberration is due to a functional bundle branch block, whereas ectopy derives from a totally abnormal activation of the ventricles. Aberration, thus, results in a "typical" bundle branch block morphology, whereas ectopy is expressed by an "atypical" bundle branch block. Specific criteria, based on analysis of leads V1 and V6, have been developed to distinguish the two conditions from each other. The criteria based on QRS configuration, however, suffer from limitations since unexpected complicating factors, such as a previous myocardial infarction, can result in an "atypical" form of bundle branch block even in the presence of supraventricular tachycardia. A new algorithm has recently been introduced, based on analysis of lead aVR only. Any of the following features, observed in this lead, pinpoints a diagnosis of ventricular tachycardia: 1) a dominant R wave (R or Rs complexes); 2) an initial q or r wave with duration > 40 ms (qR or rS complexes); 3) a notch in the descending Q wave limb in a negative (Qr or QS) complex. In the absence of these signs, the ratio between the voltages recorded during the first and the last 40 ms of the QRS complex helps distinction between ectopy and aberration: a ratio < or = 1 suggests ventricular tachycardia whereas a ratio > 1 indicates supraventricular tachycardia. A hard diagnostic problem is associated with preexcited tachycardia, the condition resulting whenever supraventricular tachycardia impulses are conducted to the ventr

Oreto, Giuseppe; Luzza, Francesco; Satullo, Gaetano; Donato, Antonino; Carbone, Vincenzo; Calabrň, Maria Pia

2009-09-01

3

FETAL QRS COMPLEX DETECTION FROM ABDOMINAL ECG: A FUZZY APPROACH  

Microsoft Academic Search

Signal processing problems related to abdominal-lea d fetal ECG include the cancellation of the maternal QRS complex, signal enhancement of the fetal QRS complex and detection of the presence of a fetal R-wave to compute the fetal heart rate. This paper describes an improved scheme for detecting the presence of the QRS complexes from the enhanced fetal electrocardiograph (ECG) signal

Khandaker Abul; Kalam Azad

4

Correlation between QRS Duration, Pulmonary Insufficiency and Right Ventricle Performance in Totally Corrected Tetralogy of Fallot  

PubMed Central

Objective Despite progresses in surgical correction of Tetralogy of Fallot, pulmonary insufficiency and progressive dysfunction of the right ventricle impress its long-term prognosis. In this study we examined the correlations between QRS duration, pulmonary insufficiency and right ventricular performance index. Methods We enrolled 57 repaired Tetralogy of Fallot patients. QRS duration on electrocardiogram, pulmonary regurgitation index (regurgitation time to diastolic time ratio), and right ventricular myocardial performance index were measured. Findings There was a strong inverse correlation between QRS duration and pulmonary regurgitation index. However, significant correlation did not exist between QRS duration and right ventricular myocardial performance index. QRS duration ?160 ms predicted severe pulmonary regurgitation with 100% sensitivity and 87% specificity. Conclusion Increased QRS duration can predict severity of pulmonary regurgitation.

Tanasan, Asadolah; Kocharian, Armen; Zanjani, Keyhan Sayadpour; Payravian, Farah K.; Torabian, Sadat

2013-01-01

5

On-line QRS complex detection using wavelet filtering  

Microsoft Academic Search

This paper presents a new QRS complex detection algorithm that can be applied in various on-line ECG processing systems. The algorithm is performed in two steps: first a wavelet transform filtering is applied to the signal, then QRS complex localization is performed using a maximum detection and peak classification algorithm. The algorithm has been tested in two phases. First QRS

L. Szilagyi; Z. Benyo; S. M. Szilagyi; A. Szlavecz; L. Nagy

2001-01-01

6

A QRS complex detection algorithm using electrocardiogram leads  

Microsoft Academic Search

A QRS complex detection algorithm was developed using the available leads of the electrocardiogram (ECG). This detector is based on the combination of two improved versions of QRS detectors available in the literature. An important characteristic of this algorithm is the possibility of using two or more ECG channels for QRS detection. The first detection method is based on a

J. C. T. B. Moraes; M. M. Freitas; F. N. Vilani; E. V. Costa

2002-01-01

7

QRS complex detection using Empirical Mode Decomposition  

Microsoft Academic Search

In this paper, we present a new Empirical Mode Decomposition based algorithm for the purpose of QRS complex detection. This algorithm requires the following stages: a high-pass filter, signal Empirical Mode Decomposition, a nonlinear transform, an integration and finally, a low-pass filter is used. In order to evaluate the proposed technique, the well known ECG MIT–BIH database has been used.

Zine-Eddine Hadj Slimane; Amine Naďt-Ali

2010-01-01

8

A Robust QRS Complex Detection Algorithm Using Dynamic Thresholds  

Microsoft Academic Search

Automatic QRS complex detection is important in ECG signal analysis. QRS detection methods are affected by the quality of the ECG recordings and the abnormalities in the ECG signals. In this paper, a generic algorithm is introduced to improve the detection of QRS complexes in arrhythmia ECG signals that suffer from: (1) non-stationary effects, (2) low signal-to-noise ratio, (3) negative

Mohamed Elgendi; Sivaram Mahalingam; Mirjam Jonkman; Friso De Boer

2008-01-01

9

On-Line QRS Complex Detection Using Wavelet Filtering.  

National Technical Information Service (NTIS)

This paper presents a new QRS complex detection algorithm that can be applied in various on-line FCC processing systems The algorithm is performed in two steps: first a wavelet transform filtering is applied to the signal, then QRS complex localization is...

L. Szilagyi Z. Benyo S. M. Szilagyi L. Nagy

2001-01-01

10

An approach to QRS complex detection using mathematical morphology  

Microsoft Academic Search

An approach to QRS complex detection based on mathematical morphology is presented. QRS complexes are detected by the application of a simple morphological operator. This operator works as a peak-valley extractor and it is controlled by the shape of the structuring element. A set (horizontal line segment) is used as a structuring element, resulting in very fast execution times. The

P. E. Trahanias

1993-01-01

11

A real time QRS complex classification method using Mahalanobis distance  

Microsoft Academic Search

An unsupervised method to recognize and classify QRS complexes was developed in order to create an automatic cardiac beat classifier in real time. After exhaustive analysis, four features extracted from the QRS complex in the time domain were selected as the ones presenting the best results: width, total sum of the areas under the positive and negative curves, total sum

J. C. T. B. Moraes; M. O. Seixas; F. N. Vilani; E. V. Costa

2002-01-01

12

The value of electrocardiography for differential diagnosis in wide QRS complex tachycardia.  

PubMed

Correct diagnosis in wide QRS complex tachycardia remains a challenge. Differential diagnosis between ventricular and supraventricular tachycardia has important therapeutic and prognostic implications, and although data from clinical history and physical examination may suggest a particular origin, it is the 12-lead surface electrocardiogram that usually enables this differentiation. Since 1978, various electrocardiographic criteria have been proposed for the differential diagnosis of wide complex tachycardias, particularly the presence of atrioventricular dissociation, and the axis, duration and morphology of QRS complexes. Despite the wide variety of criteria, diagnosis is still often difficult, and errors can have serious consequences. To reduce such errors, several differential diagnosis algorithms have been proposed since 1991. However, in a small percentage of wide QRS tachycardias the diagnosis remains uncertain and in these the wisest decision is to treat them as ventricular tachycardias. The authors' objective was to review the main electrocardiographic criteria and differential diagnosis algorithms of wide QRS tachycardia. PMID:24656320

Sousa, Pedro A; Pereira, Salomé; Candeias, Rui; de Jesus, Ilídio

2014-03-01

13

A prolonged QRS duration on surface electrocardiogram is a specific indicator of left ventricular dysfunction  

Microsoft Academic Search

Objective. We sought to determine whether a prolonged QRS interval duration is associated with decreased left ventricular (LV) systolic function.Background. The 12-lead electrocardiogram (ECG) is a routine test for suspected cardiac disease. Although several scoring systems have been devised to estimate LV systolic function, no studies have examined the direct relationship between QRS duration alone and LV systolic function.Methods. We

Rachel L Murkofsky; George Dangas; Joseph A Diamond; Davendra Mehta; Abraham Schaffer; John A Ambrose

1998-01-01

14

Cardiac resynchronisation therapy in patients with heart failure and a normal QRS duration: the RESPOND study  

Microsoft Academic Search

ObjectivesTo evaluate the clinical response to cardiac resynchronisation therapy (CRT) in patients with heart failure and a normal QRS duration (<120 ms).SettingSingle centre.Patients60 patients with heart failure and a normal QRS duration receiving optimal pharmacological treatment (OPT).InterventionsPatients were randomly assigned to CRT (n=29) or to a control group (OPT, n=31). Cardiovascular magnetic resonance was used in order to avoid scar

Paul W X Foley; Kiran Patel; Nick Irwin; John E Sanderson; Michael P Frenneaux; Russell E A Smith; Berthold Stegemann; Francisco Leyva

2011-01-01

15

Myocardial ischemia analysis based on electrocardiogram QRS complex.  

PubMed

Electrocardiogram (ECG) is an economic, convenient, and non-invasive detecting tool in myocardial ischemia (MI), and its clinical appearance is mainly exhibited by the changes in ST-T complex. Recently, QRS complex characters were proposed to analyze MI by more and more researchers. In this paper, various QRS complex characters were extracted in ECG signals, and their relationship was analyzed systematically. As a result, these characters were divided into two groups, and there existed good relationship among them for each group, while the poor relationship between the groups. Then these QRS complex characters were applied for statistical analysis on MI, and five characters had significant differences after ECG recording verification, which were: QRS upward and downward slopes, transient heart rate, angle R and angle Q. On the other hand, these QRS complex characters were analyzed in frequency domain. Experimental results showed that the frequency features of RR interval series (Heart Rate Variability, HRV), and QRS barycenter sequence had significant differences between MI states and normal states. Moreover, QRS barycenter sequence performed better. PMID:21971843

Song, Jinzhong; Yan, Hong; Xu, Zhi; Yu, Xinming; Zhu, Ruiyun

2011-12-01

16

Adaptive Threshold for QRS Complex Detection Based on Wavelet Transform  

Microsoft Academic Search

This paper presents a novel approach, adaptive threshold algorithm, for QRS complex detection. It is based on two-to-four scales in COIFLET wavelet transform. Two initial thresholds are defined as up-limited-threshold (ULT) and down-limited-threshold (DLT) at the beginning of the detection. The system then automatically adjusts the values of the threshold to achieve optimal QRS detection. Simulation work shows that adaptive

Xiaomin Xu; Ying Liu

2005-01-01

17

Common variants in 22 loci are associated with QRS duration and cardiac ventricular conduction  

PubMed Central

QRS interval on the electrocardiogram reflects ventricular depolarization and conduction time, and is a risk factor for mortality, sudden death, and heart failure. We performed a genome-wide association meta-analysis in 40,407 European-descent individuals from 14 studies, with further genotyping in 7170 additional Europeans, and identified 22 loci associated with QRS duration (P < 5 × 10?8). These loci map in or near genes in pathways with established roles in ventricular conduction such as sodium channels, transcription factors, and calcium-handling proteins, but also point to novel biologic processes, such as kinase inhibitors and genes related to tumorigenesis. We demonstrate that SCN10A, a gene at our most significant locus, is expressed in the mouse ventricular conduction system, and treatment with a selective SCN10A blocker prolongs QRS duration. These findings extend our current knowledge of ventricular depolarization and conduction.

Sotoodehnia, Nona; Isaacs, Aaron; de Bakker, Paul I.W.; Dorr, Marcus; Newton-Cheh, Christopher; Nolte, Ilja M.; van der Harst, Pim; Muller, Martina; Eijgelsheim, Mark; Alonso, Alvaro; Hicks, Andrew A.; Padmanabhan, Sandosh; Hayward, Caroline; Smith, Albert Vernon; Polasek, Ozren; Giovannone, Steven; Fu, Jingyuan; Magnani, Jared W.; Marciante, Kristin D.; Pfeufer, Arne; Gharib, Sina A.; Teumer, Alexander; Li, Man; Bis, Joshua C.; Rivadeneira, Fernando; Aspelund, Thor; Kottgen, Anna; Johnson, Toby; Rice, Kenneth; Sie, Mark P.S.; Wang, Amanda Ying; Klopp, Norman; Fuchsberger, Christian; Wild, Sarah H.; Leach, Irene Mateo; Estrada, Karol; Volker, Uwe; Wright, Alan F.; Asselbergs, Folkert W.; Qu, Jiaxiang; Chakravarti, Aravinda; Sinner, Moritz F.; Kors, Jan A.; Petersmann, Astrid; Harris, Tamara B.; Soliman, Elsayed Z.; Munroe, Patricia B.; Psaty, Bruce M.; Oostra, Ben A.; Cupples, L. Adrienne; Perz, Siegfried; de Boer, Rudolf A.; Uitterlinden, Andre G.; Vozke, Henry; Spector, Timothy D.; Liu, Fang-Yu; Boerwinkle, Eric; Dominiczak, Anna F.; Rotter, Jerome I.; van Herpen, Ge; Levy, Daniel; Wichmann, H.-Erich; van Gilst, Wiek H.; Witteman, Jacqueline C.M.; Kroemer, Heyo K.; Kao, W.H. Linda; Heckbert, Susan R.; Meitinger, Thomas; Hofman, Albert; Campbell, Harry; Folsom, Aaron R.; van Veldhuisen, Dirk J.; Schwienbacher, Christine; O'Donnell, Christopher J.; Volpato, Claudia Beu; Caulfield, Mark J.; Connell, John M.; Launer, Lenore; Lu, Xiaowen; Franke, Lude; Fehrmann, Rudolf S.N.; Meerman, Gerard te; Groen, Harry J.M.; Weersma, Rinse K.; van den Berg, Leonard H.; Wijmenga, Cisca; Ophoff, Roel A.; Navis, Gerjan; Rudan, Igor; Snieder, Harold; Wilson, James F.; Pramstaller, Peter P.; Siscovick, David S.; Wang, Thomas J.; Gudnason, Vilmundur; van Duijn, Cornelia M.; Felix, Stephan B.; Fishman, Glenn I.; Jamshidi, Yalda; Stricker, Bruno H Ch; Samani, Nilesh J.; Kaab, Stefan; Arking, Dan E.

2010-01-01

18

[QRS complex detection using empirical mode decomposition and windowing technique].  

PubMed

A QRS complex detection algorithm based on empirical mode decomposition (EMD) and adaptive windowing technique is proposed in this paper. In this algorithm we mainly used Hilbert-Huang transform to propose EMD method suitable for QRS complex detection, with which the 30th signal in sddb database and the 208th signal in mit-db database could be processed, and then obtained R wave detection results. At the same time, Q and S points' detection technique was analyzed with adaptive windowing technique. The detection results, through proceeding R wave detection on part data of MIT/BIT arrhythmia database, showed that the proposed algorithm in this paper had a very good detection effect, and that its average correct detection rate of R wave reached 99.62%, its average sensitivity of QRS complex was 98.91%, and the corresponding average specificity was 99.35%. PMID:22826929

Zhang, Kaiyu; Wang, Li; Wang, Yujing; Song, Lixin

2012-06-01

19

QRS complexes detection for ECG signal: The Difference Operation Method  

Microsoft Academic Search

This paper proposes a simple and reliable method termed the Difference Operation Method (DOM) to detect the QRS complex of an electrocardiogram (ECG) signal. The proposed DOM includes two stages. The first stage is to find the point R by applying the difference equation operation to an ECG signal. The second stage looks for the points Q and S based

Yun-chi Yeh; Wen-june Wang

2008-01-01

20

QRS complex detection based on Symmlets wavelet function  

Microsoft Academic Search

Wavelet theory is inspired the development of a strong methodology for signal processing and can be used as a good tool for non-stationary electrocardiogram (ECG signal) detection. In this paper a QRS complex detection method is proposed based on wavelet transform (WT) with Symmlets function. The proposed method show sharp results for ECG detection parameters. The fiducial points are easily

Khaled Daqrouq; Ibrahim N. Abu-Isbeih; Abdel-Rahman AI-Qawasmi

2008-01-01

21

Wavelet-transform-based QRS complex detection in on-line Holter systems  

Microsoft Academic Search

Presents a QRS complex detection algorithm that can be applied in on-line Holter systems. The algorithm is performed in two steps: first the wavelet transform is applied to filter the signal, then QRS complex localization is accomplished using a maximum detection algorithm. The algorithm has been tested in two phases. First the QRS detection in ECG registrations from the MIT-BIH

L. Szilagyi

1999-01-01

22

Several common variants modulate heart rate, PR interval and QRS duration  

Microsoft Academic Search

Electrocardiographic measures are indicative of the function of the cardiac conduction system. To search for sequence variants that modulate heart rate, PR interval and QRS duration in individuals of European descent, we performed a genome-wide association study in ?10,000 individuals and followed up the top signals in an additional ?10,000 individuals. We identified several genome-wide significant associations (with P <

Daniel F Gudbjartsson; David O Arnar; Gudmar Thorleifsson; Gudmundur Thorgeirsson; Hrafnhildur Stefansdottir; Sigurjon A Gudjonsson; Aslaug Jonasdottir; Ellisiv B Mathiesen; Inger Njřlstad; Audhild Nyrnes; Tom Wilsgaard; Erin M Hald; Kristian Hveem; Camilla Stoltenberg; Maja-Lisa Lřchen; Augustine Kong; Unnur Thorsteinsdottir; Hilma Holm; Kari Stefansson

2010-01-01

23

Relationship between fragmented QRS complex and left ventricular systolic and diastolic function in kidney transplant patients.  

PubMed

Background-Kidney transplant is a most important replacement therapy. It reduces cardiovascular mortality and morbidity but does not fully correct impairments in cardiac function. Fragmented QRS (fQRS) complex includes various RSR' patterns with different QRS complex morphologies on electrocardiograms.Objective-To analyze fQRS frequency and the relationship between fQRS and left ventricular function in kidney transplant patients.Method-After demographic data on 39 kidney transplant patients were recorded and biochemical parameters were investigated, electrocardiograms were evaluated for the presence of fQRS. Left ventricular ejection fraction, mitral annular plane systolic excursion, peak early diastolic mitral annular velocities, late diastolic mitral annular velocities, and systolic mitral annular velocity were analyzed.Results-Fragmented QRS was detected in 16 patients. A history of hypertension was associated with the presence of fQRS. Patients with fQRS had significantly lower systolic and peak early diastolic mitral annular velocities, mitral annular plane systolic excursion, and left ventricular ejection fraction than did patients without fQRS (P= .03, .01, <.001, and .03, respectively).Conclusion-Detection of fQRS on electrocardiograms may be useful in predicting systolic and diastolic dysfunction of the left ventricle in kidney transplant patients. PMID:24919731

Ulusoy, Sükrü; Ozkan, Gulsum; Adar, Adem; Bekta?, Hüseyin; K?r??, Abdulkadir; Celik, Sükrü

2014-06-01

24

Several common variants modulate heart rate, PR interval and QRS duration.  

PubMed

Electrocardiographic measures are indicative of the function of the cardiac conduction system. To search for sequence variants that modulate heart rate, PR interval and QRS duration in individuals of European descent, we performed a genome-wide association study in approximately 10,000 individuals and followed up the top signals in an additional approximately 10,000 individuals. We identified several genome-wide significant associations (with P < 1.6 x 10(-7)). We identified one locus for heart rate (MYH6), four for PR interval (TBX5, SCN10A, CAV1 and ARHGAP24) and four for QRS duration (TBX5, SCN10A, 6p21 and 10q21). We tested for association between these loci and subjects with selected arrhythmias in Icelandic and Norwegian case-control sample sets. We observed correlations between TBX5 and CAV1 and atrial fibrillation (P = 4.0 x 10(-5) and P = 0.00032, respectively), between TBX5 and advanced atrioventricular block (P = 0.0067), and between SCN10A and pacemaker implantation (P = 0.0029). We also replicated previously described associations with the QT interval. PMID:20062063

Holm, Hilma; Gudbjartsson, Daniel F; Arnar, David O; Thorleifsson, Gudmar; Thorgeirsson, Gudmundur; Stefansdottir, Hrafnhildur; Gudjonsson, Sigurjon A; Jonasdottir, Aslaug; Mathiesen, Ellisiv B; Njřlstad, Inger; Nyrnes, Audhild; Wilsgaard, Tom; Hald, Erin M; Hveem, Kristian; Stoltenberg, Camilla; Lřchen, Maja-Lisa; Kong, Augustine; Thorsteinsdottir, Unnur; Stefansson, Kari

2010-02-01

25

Current algorithms for the diagnosis of wide QRS complex tachycardias.  

PubMed

The differential diagnosis of a regular, monomorphic wide QRS complex tachycardia (WCT) mechanism represents a great diagnostic dilemma commonly encountered by the practicing physician, which has important implications for acute arrhythmia management, further work-up, prognosis and chronic management as well. This comprehensive review discusses the causes and differential diagnosis of WCT, and since the ECG remains the cornerstone of WCT differential diagnosis, focuses on the application and diagnostic value of different ECG criteria and algorithms in this setting and also provides a practical clinical approach to patients with WCTs. PMID:24827795

Vereckei, Andras

2014-08-01

26

QRS duration on electrocardiography and cardiovascular mortality (from the National Health and Nutrition Examination Survey-III).  

PubMed

The relation of bundle branch block (BBB) with adverse outcome is controversial. We hypothesized that increased QRS duration is an independent predictor of cardiovascular (CV) mortality in a cross-sectional US population. This is a retrospective cohort study on prospectively collected data to assess the relationship between QRS duration on routine ECG and CV mortality. Participants included 8,527 patients with ECG data available from the National Health and Nutrition Examination Survey data set, representing 74,062,796 individuals in the United States. Mean age was 60.5 ± 13.6 years. Most subjects were white (87%) and women (53%). During the follow-up period of 106,244.6 person-years, 1,433 CV deaths occurred. Multivariate analysis revealed that the highest quartile of QRS duration was associated with higher CV mortality than lowest quartile (hazard ratio [HR] 1.3, 95% confidence interval [CI] 1.01 to 1.7, p = 0.04) after adjustment for established risk factors. Both left BBB (HR 2.4, 95% CI 1.3 to 4.7, p = 0.009) and right BBB (HR 1.90, 95% CI 1.2 to 3.0, p = 0.008) were significantly associated with increased CV mortality. The addition of the QRS duration in 10-millisecond increments to the Framingham Risk Score model resulted in 4.4% overall net reclassification improvement (95% CI 0.02 to 0.04; p = 0.00006). In conclusion, increased QRS duration was found to be an independent predictor of CV mortality in this cross-sectional US population. A model including QRS duration in addition to traditional risk factors was associated with improved CV risk prediction. PMID:23726176

Badheka, Apurva Omkar; Singh, Vikas; Patel, Nileshkumar Jasmatbhai; Deshmukh, Abhishek; Shah, Neeraj; Chothani, Ankit; Mehta, Kathan; Grover, Peeyush; Savani, Ghanshyambhai Tulsibhai; Gupta, Sandeepkumar; Rathod, Ankit; Marzouka, George Robert; Mitrani, Raul David; Moscucci, Mauro; Cohen, Mauricio Gabriel

2013-09-01

27

Quick QRS Complex Detection for On-Line ECG and Holter Systems  

Microsoft Academic Search

This paper presents a new QRS complex detection algorithm that can be applied in various on-line ECG processing systems. The algorithm is performed in two steps: first a wavelet transform filtering is applied to the signal, then QRS complex localization is performed using a maximum detection and peak classification algorithm. The algorithm has been tested in two phases. First the

László Szilágyi; Sándor M. Szilágyi; Attila Frigy; Sándor E. László; Levente K. Görög; Zoltán Benyó

2005-01-01

28

QRS complex detection by the combination of maxima and zero-crossing points of wavelet transform  

Microsoft Academic Search

The proposed algorithm uses the wavelet transform (WT) to detect the QRS complex of an electrocardiogram (ECG). Compared to other algorithms, which only use WT zero-crossing points, this algorithm detects the ECG characteristic points by a combination of the maxima and the zero-crossings of the WT. This algorithm can easily distinguish the QRS complex by comparison with prior work. The

Yanli Zheng; Guangshu Hu

1998-01-01

29

A new approach of QRS complex detection based on matched filtering and triangle character analysis.  

PubMed

QRS complex detection usually provides the fundamentals to automated electrocardiogram (ECG) analysis. In this paper, a new approach of QRS complex detection without the stage of noise suppression was developed and evaluated, which was based on the combination of two techniques: matched filtering and triangle character analysis. Firstly, a template of QRS complex was selected automatically by the triangle character in ECG, and then it was time-reversed after removing its direct current component. Secondly, matched filtering was implemented at low computational cost by finite impulse response, which further enhanced QRS complex and attenuated non-QRS regions containing P-wave, T-wave and various noise components. Subsequently, triangle structure-based threshold decision was processed to detect QRS complexes. And RR intervals and triangle structures were further analyzed for the reduction of false-positive and false-negative detections. Finally, the performance of the proposed algorithm was tested on all 48 records of the MIT-BIH Arrhythmia Database. The results demonstrated that the detection rate reached 99.62 %, the sensitivity got 99.78 %, and the positive prediction was 99.85 %. In addition, the proposed method was able to identify QRS complexes reliably even under the condition of poor signal quality. PMID:22806315

Li, Yanjun; Yan, Hong; Hong, Feng; Song, Jinzhong

2012-09-01

30

Real Time Matched Filter Detection of the Qrs Complex by Replica Correlation.  

National Technical Information Service (NTIS)

The report describes an approach to optimum detection of each cardiac cycle from noisy electrocardiograms. A filter matched to the QRS complex of the electrocardiogram is proposed to achieve the results. It is demonstrated analytically that such a filter ...

A. J. Welch C. A. Braun F. B. Vogt F. X. Bostick P. C. Richardson

1970-01-01

31

A QRS Complex Detection Algorithm Based on Mathematical Morphology and Envelope  

Microsoft Academic Search

The QRS complex detection is very important to ECG analysis. This paper aims to present an algorithm of QRS complex detection based on mathematical morphology and envelope. Baseline wandering is removed from ECG signal by morphological method. Then the signal gets the envelope through a low-pass filter, improving signal-to-noise .The performance of the algorithm is evaluated with MIT-BIH database. The

Yongli Chen; Huilong Duan

2005-01-01

32

Usefulness of spatial dispersion of QRS duration in predicting mortality in patients with mild to moderate chronic heart failure.  

PubMed

To prospectively evaluate the prognostic significance of spatial dispersion of QRS duration (S-QRSd) on a signal-averaged electrocardiogram in patients with chronic heart failure (CHF), we studied 114 consecutive stable outpatients with radionuclide left ventricular ejection fraction <40%. Cardiac and sudden deaths were significantly more often observed in patients with than without abnormal S-QRSd. S-QRSd is a powerful prognostic marker of the mortality in patients with mild to moderate CHF. PMID:15464690

Yamada, Takahisa; Shimonagata, Tsuyoshi; Misaki, Naoyuki; Asai, Mitsutoshi; Makino, Nobuhiko; Kioka, Hidetaka; Tamaki, Shunsuke; Fukunami, Masatake

2004-10-01

33

Methodology for automated detection of fragmentation in QRS complex of Standard 12-lead ECG.  

PubMed

Fragmented QRS (f-QRS) has been found to have higher sensitivity and/or specificity values for several diseases including remote and acute myocardial infarction, cardiac sarcoidosis etc, compared to other conventional bio-markers viz. Q-wave, ST-elevation etc. Several of these diseases do not have a reliable bio-marker and hence, patients suffering from them have to undergo expensive and sometimes invasive tests for diagnosis viz. myocardial biopsy, cardiac catheterization etc. This paper proposes automation of fragmentation detection which will lead to a more reliable diagnosis and therapy reducing human error, time consumption and thereby alleviating the need of enormous training required for detection of fragmentation. In this paper, we propose a novel approach to detect the discontinuities present in QRS complex of standard 12-lead ECG, known as fragmented QRS, using Discrete Wavelet transform (DWT) targeting both hospital-based and remote health monitoring environments. Fragmentation Detection Algorithm (FDA) was designed and modeled using PhysioNet's PTBDB and upon reiterative refinements it successfully detected all discontinuities in the QRS complex. The QRS complexes of 31 patients obtained randomly from PhysioNet's PTBDB were examined by two experienced cardiologists and the measurements obtained were compared with the results of our proposed FDA leading to 89.8% agreement among them. PMID:24110556

Maheshwari, Sidharth; Acharyya, Amit; Puddu, Paolo Emilio; Schiariti, Michele

2013-01-01

34

Time-Voltage QRS Area of the 12Lead Electrocardiogram Detection of Left Ventricular Hypertrophy  

Microsoft Academic Search

Identification of left ventricular hypertrophy (LVH) using 12-lead ECG criteria based primarily on QRS amplitudes has been limited by poor sensitivity at acceptable levels of specificity. Because the product of QRS voltage and duration, as an approximation of the time-voltage area of the QRS complex, can improve accuracy of the 12-lead ECG for LVH, we examined the diagnostic value of

Peter M. Okin; Mary J. Roman; Richard B. Devereux; Thomas G. Pickering; Jeffrey S. Borer; Paul Kligfield

2010-01-01

35

Common variants in 22 loci are associated with QRS duration and cardiac ventricular conduction  

Microsoft Academic Search

The QRS interval, from the beginning of the Q wave to the end of the S wave on an electrocardiogram, reflects ventricular depolarization and conduction time and is a risk factor for mortality, sudden death and heart failure. We performed a genome-wide association meta-analysis in 40,407 individuals of European descent from 14 studies, with further genotyping in 7,170 additional Europeans,

Aaron Isaacs; Paul I W de Bakker; Marcus Dörr; Christopher Newton-Cheh; Ilja M Nolte; Pim van der Harst; Martina Müller; Mark Eijgelsheim; Alvaro Alonso; Andrew A Hicks; Sandosh Padmanabhan; Caroline Hayward; Albert Vernon Smith; Ozren Polasek; Steven Giovannone; Jingyuan Fu; Jared W Magnani; Kristin D Marciante; Arne Pfeufer; Sina A Gharib; Alexander Teumer; Man Li; Joshua C Bis; Fernando Rivadeneira; Thor Aspelund; Anna Köttgen; Toby Johnson; Kenneth Rice; Mark P S Sie; Ying A Wang; Norman Klopp; Christian Fuchsberger; Sarah H Wild; Irene Mateo Leach; Karol Estrada; Uwe Völker; Alan F Wright; Folkert W Asselbergs; Jiaxiang Qu; Aravinda Chakravarti; Moritz F Sinner; Jan A Kors; Astrid Petersmann; Tamara B Harris; Elsayed Z Soliman; Patricia B Munroe; Bruce M Psaty; Ben A Oostra; L Adrienne Cupples; Siegfried Perz; Rudolf A de Boer; André G Uitterlinden; Henry Völzke; Timothy D Spector; Fang-Yu Liu; Eric Boerwinkle; Anna F Dominiczak; Jerome I Rotter; Gé van Herpen; Daniel Levy; H-Erich Wichmann; Wiek H van Gilst; Jacqueline C M Witteman; Heyo K Kroemer; W H Linda Kao; Susan R Heckbert; Thomas Meitinger; Albert Hofman; Harry Campbell; Aaron R Folsom; Dirk J van Veldhuisen; Christine Schwienbacher; Christopher J O'Donnell; Claudia Beu Volpato; Mark J Caulfield; John M Connell; Lenore Launer; Xiaowen Lu; Lude Franke; Rudolf S N Fehrmann; Gerard te Meerman; Harry J M Groen; Rinse K Weersma; Leonard H van den Berg; Cisca Wijmenga; Roel A Ophoff; Gerjan Navis; Igor Rudan; Harold Snieder; James F Wilson; Peter P Pramstaller; David S Siscovick; Thomas J Wang; Vilmundur Gudnason; Cornelia M van Duijn; Stephan B Felix; Glenn I Fishman; Yalda Jamshidi; Bruno H Ch Stricker; Nilesh J Samani; Nona Sotoodehnia; Stefan Kääb; Dan E Arking

2010-01-01

36

An efficient unsupervised fetal QRS complex detection from abdominal maternal ECG.  

PubMed

Non-invasive fetal heart rate is of great relevance in clinical practice to monitor fetal health state during pregnancy. To date, however, despite significant advances in the field of electrocardiography, the analysis of abdominal fetal ECG is considered a challenging problem for biomedical and signal processing communities. This is mainly due to the low signal-to-noise ratio of fetal ECG and difficulties in cancellation of maternal QRS complexes, motion and electromyographic artefacts. In this paper we present an efficient unsupervised algorithm for fetal QRS complex detection from abdominal multichannel signal recordings combining ICA and maternal ECG cancelling, which outperforms each single method. The signal is first pre-processed to remove impulsive artefacts, baseline wandering and power line interference. The following steps are then applied: maternal ECG extraction through independent component analysis (ICA); maternal QRS detection; maternal ECG cancelling through weighted singular value decomposition; enhancing of fetal ECG through ICA and fetal QRS detection. We participated in the Physionet/Computing in Cardiology Challenge 2013, obtaining the top official scores of the challenge (among 53 teams of participants) of event 1 and event 2 concerning fetal heart rate and fetal interbeat intervals estimation section. The developed algorithms are released as open-source on the Physionet website. PMID:25069520

Varanini, M; Tartarisco, G; Billeci, L; Macerata, A; Pioggia, G; Balocchi, R

2014-08-01

37

Effects of cardiac resynchronisation therapy in patients with heart failure having a narrow QRS Complex enrolled in PROSPECT  

Microsoft Academic Search

IntroductionCurrent guidelines recommend cardiac resynchronisation therapy (CRT) in patients with severe symptomatic heart failure, depressed left ventricular (LV) systolic function and a wide QRS complex (?120 ms). However, patients with heart failure having a narrow QRS complex might also benefit from CRT.Design setting patients interventionsDuring the Predictors of Response to Cardiac Resynchronisation Therapy (PROSPECT) trial, 41 patients were enrolled in

R. J. van Bommel; J. Gorcsan; E. S. Chung; W. T. Abraham; F. T. Gjestvang; C. Leclercq; M. J. Monaghan; P. Nihoyannopoulos; C. Peraldo; C.-M. Yu; M. Demas; B. Gerritse; J. J. Bax

2010-01-01

38

QRS wave detection  

Microsoft Academic Search

A QRS complex detector based on optimum predetection with a matched filter is described. In order to improve the accuracy\\u000a of the QRS complex recognition under conditions of Gaussian noise and variable QRS amplitude, the first derivative of the\\u000a e.c.g. was used with zero threshold detection. In addition, two nonlinear circuits cut off low amplitude noise and all spikes\\u000a which

J. Fraden; M. R. Neuman

1980-01-01

39

Neural network for automatic anomalous QRS complex detection  

Microsoft Academic Search

An application of the back-propagation (BP) neural network (NN) for the discrimination between normal and pathological electrocardiogram (ECG) complexes is presented. The BP is used as a part of an unsupervised method: the network output has not been used to discriminate normal and pathological complexes, but only to extract the prototype complex of the analyzed ECG. An attempt is made

A. Casaleggio; M. Morando; S. Ridella

1990-01-01

40

A FPGA system for QRS complex detection based on Integer Wavelet Transform  

NASA Astrophysics Data System (ADS)

Due to complexity of their mathematical computation, many QRS detectors are implemented in software and cannot operate in real time. The paper presents a real-time hardware based solution for this task. To filter ECG signal and to extract QRS complex it employs the Integer Wavelet Transform. The system includes several components and is incorporated in a single FPGA chip what makes it suitable for direct embedding in medical instruments or wearable health care devices. It has sufficient accuracy (about 95%), showing remarkable noise immunity and low cost. Additionally, each system component is composed of several identical blocks/cells what makes the design highly generic. The capacity of today existing FPGAs allows even dozens of detectors to be placed in a single chip. After the theoretical introduction of wavelets and the review of their application in QRS detection, it will be shown how some basic wavelets can be optimized for easy hardware implementation. For this purpose the migration to the integer arithmetic and additional simplifications in calculations has to be done. Further, the system architecture will be presented with the demonstrations in both, software simulation and real testing. At the end, the working performances and preliminary results will be outlined and discussed. The same principle can be applied with other signals where the hardware implementation of wavelet transform can be of benefit.

Stojanovi?, R.; Karadagli?, D.; Mirkovi?, M.; Miloševi?, D.

2011-01-01

41

Electrocardiographic identification of increased left ventricular mass by simple voltage-duration products  

Microsoft Academic Search

Objectives. This study was conducted to validate the hypothesis that the product of QRS voltage and duration, as an approximation of the time-voltage area of the QRS complex, can improve the electrocardiographic (ECG) detection of echocardiographically determined left ventricular hypertrophy and to further assess the relative contribution of QRS duration to the ECG detection of hypertrophy.Background. The ECG identification of

Peter M. Okin; Mary J. Roman; Richard B. Devereux; Paul Kligfield

1995-01-01

42

On the relationship between block of the cardiac Na+ channel and drug-induced prolongation of the QRS complex  

PubMed Central

BACKGROUND AND PURPOSE Inhibition of the human cardiac Na+ channel (hNav1.5) can prolong the QRS complex and has been associated with increased mortality in patients with underlying cardiovascular disease. The safety implications of blocking hNav1.5 channels suggest the need to test for this activity early in drug discovery in order to design out any potential liability. However, interpretation of hNav1.5 blocking potency requires knowledge of how hNav1.5 block translates into prolongation of the QRS complex. EXPERIMENTAL APPROACH We tested Class I anti-arrhythmics, other known QRS prolonging drugs and drugs not reported to prolong the QRS complex. Their block of hNav1.5 channels (as IC50 values) was measured in an automated electrophysiology-based assay. These IC50 values were compared with published reports of the corresponding unbound (free) plasma concentrations attained during clinical use (fCmax) to provide an IC50 : fCmax ratio. KEY RESULTS For 42 Class I anti-arrhythmics and other QRS prolonging drugs, 67% had IC50 : fCmax ratios <30. For 55 non-QRS prolonging drugs tested, 72% had ratios >100. Finally, we determined the relationship between the IC50 value and the free drug concentration associated with prolongation of the QRS complex in humans. For 37 drugs, QRS complex prolongation was observed at free plasma concentrations that were about 15-fold lower than the corresponding IC50 at hNav1.5 channels. CONCLUSIONS AND IMPLICATIONS A margin of 30- to 100-fold between hNav1.5 IC50 and fCmax appears to confer an acceptable degree of safety from QRS prolongation. QRS prolongation occurs on average at free plasma levels 15-fold below the IC50 at hNav1.5 channels. LINKED ARTICLE This article is commented on by Gintant et al., pp. 254–259 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2011.01433.x

Harmer, AR; Valentin, J-P; Pollard, CE

2011-01-01

43

Radial dyssynchrony assessed by cardiovascular magnetic resonance in relation to left ventricular function, myocardial scarring and QRS duration in patients with heart failure  

PubMed Central

Background Intuitively, cardiac dyssynchrony is the inevitable result of myocardial injury. We hypothezised that radial dyssynchrony reflects left ventricular remodeling, myocardial scarring, QRS duration and impaired LV function and that, accordingly, it is detectable in all patients with heart failure. Methods 225 patients with heart failure, grouped according to QRS duration of <120 ms (A, n = 75), between 120-149 ms (B, n = 75) or ?150 ms (C, n = 75), and 50 healthy controls underwent assessment of radial dyssynchrony using the cardiovascular magnetic resonance tissue synchronization index (CMR-TSI = SD of time to peak inward endocardial motion in up to 60 myocardial segments). Results Compared to 50 healthy controls (21.8 ± 6.3 ms [mean ± SD]), CMR-TSI was higher in A (74.8 ± 34.6 ms), B (92.4 ± 39.5 ms) and C (104.6 ± 45.6 ms) (all p < 0.0001). Adopting a cut-off CMR-TSI of 34.4 ms (21.8 plus 2xSD for controls) for the definition of dyssynchrony, it was present in 91% in A, 95% in B and 99% in C. Amongst patients in NYHA class III or IV, with a LVEF<35% and a QRS>120 ms, 99% had dyssynchrony. Amongst those with a QRS<120 ms, 91% had dyssynchrony. Across the study sample, CMR-TSI was related positively to left ventricular volumes (p < 0.0001) and inversely to LVEF (CMR-TSI = 178.3 e (-0.033 LVEF) ms, p < 0.0001). Conclusion Radial dyssynchrony is almost universal in patients with heart failure. This vies against the notion that a lack of response to CRT is related to a lack of dyssynchrony.

2009-01-01

44

Prognostic value of QRS duration after transcatheter aortic valve implantation for aortic stenosis using the CoreValve.  

PubMed

Transcatheter aortic valve implantation (TAVI) is effective in treating severe aortic stenosis in high-risk surgical patients. We evaluated the value of the QRS duration (QRSd) in predicting the mid-term morbidity and mortality after TAVI. We conducted a prospective cohort study of 91 consecutive patients who underwent TAVI using the CoreValve at our teaching hospital cardiology unit in 2008 to 2010 who survived to hospital discharge; 57% were women, and their mean age was 84 ± 7 years. The QRSd at discharge was used to classify the patients into 3 groups: QRSd ?120 ms, n = 18 (20%); QRSd >120 ms but ?150 ms, n = 30 (33%); and QRSd >150 ms, n = 43 (47%). We used 2 end points: (1) all-cause mortality and (2) all-cause mortality or admission for heart failure. After a median of 12 months, the normal-QRSd patients showed a trend toward, or had, significantly better overall survival and survival free of admission for heart failure compared with the intermediate-QRSd group (p = 0.084 and p = 0.002, respectively) and the long-QRSd group (p = 0.015 and p = 0.001, respectively). The factors significantly associated with all-cause mortality were the Society of Thoracic Surgeons score, aortic valve area, post-TAVI dilation, acute kidney injury, hospital days after TAVI, and QRSd at discharge. On multivariate analysis, QRSd was the strongest independent predictor of all-cause mortality (hazard ratio 1.036, 95% confidence interval 1.016 to 1.056; p <0.001) and all-cause mortality or heart failure admission (hazard ratio 1.025, 95% confidence interval 1.011 to 1.039; p <0.001). The other independent predictors were the Society of Thoracic Surgeons score, acute kidney injury, and post-TAVI hospital days. In conclusion, a longer QRSd after TAVI was associated with greater morbidity and mortality after 12 months. The QRSd at discharge independently predicted mortality and morbidity after TAVI. PMID:23528030

Meguro, Kentaro; Lellouche, Nicolas; Yamamoto, Masanori; Fougeres, Emilie; Monin, Jean-Luc; Lim, Pascal; Mouillet, Gauthier; Dubois-Rande, Jean-Luc; Teiger, Emmanuel

2013-06-15

45

Wavelets for QRS Detection.  

National Technical Information Service (NTIS)

This paper examines the use of wavelets for the detection of QRS complex in ECG. Wavelets provide temporal and spectral information simultaneously and offer flexibility with a choice of wavelet functions with different properties. This research has examin...

H. A. Dinh D. K. Kumar N. D. Pah P. Burton

2001-01-01

46

Variations of QRS Morphology in Patients with Dilated Cardiomyopathy; Clinical and Prognostic Implications  

PubMed Central

The QRS represents the simultaneous activation of the right and left ventricles, although most of the QRS waveform is derived from the larger left ventricular musculature. Although normal QRS duration is <100 millisecond (ms), its duration and shape are quite variable from patient to patient in idiopathic dilated cardiomyopathy (IDCM). Prolongation of QRS occurs in 14% to 47% of heart failure (HF) patients. Left bundle branch block (LBBB) is far more common than right bundle branch block (RBBB). Dyssynchronous left ventricular activation due to LBBB and other intraventricular conduction blocks provides the rationale for the use of cardiac resynchronization therapy with biventricular pacing in patients with IDCM. Fragmented QRS (fQRS) is a marker of depolarization abnormality and present in significant number of the patients with IDCM and narrow QRS complexes. It is associated with arrhythmic events and intraventricular dyssynchrony. The purpose of this manuscript is to present an overview on some clinical, echocardiographic and prognostic implications of various QRS morphologies in patients with IDCM.

Akgun, Taylan; Kalkan, Sedat; Tigen, Mustafa Kursat

2014-01-01

47

Fragmented QRS in patients with systemic lupus erythematosus.  

PubMed

Abstract Introduction. Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with a variety of clinical features. Cardiac involvement is present in more than half of the patients with SLE. Fragmentation of QRS (fQRS) is presumed marker of cardiovascular risk and has not been previously evaluated in SLE. Methods. A total of 56 women previously diagnosed with SLE were recruited. In addition, a control group consisting of 51 healthy people was formed. QRS complexes were also evaluated in terms of fragmentations. All patients with SLE and control subjects underwent transthoracic echocardiographic examination. Erythrocyte sedimentation rate and C-reactive protein levels were also obtained. Results. Frequency of fQRS was higher in patients with SLE (41% vs. 21%, p = 0.03). Left ventricular posterior wall thickness and mass index were higher in the patients with SLE. CRP levels and age were significantly higher, and disease duration was significantly longer in the fQRS(+) group (p = 0.02, 0.01, and 0.006, respectively). Conclusion. A careful cardiovascular evaluation and follow-up is essential to continuously improve survival in SLE. For this purpose, fQRS may be used for the early detection in patients with SLE. PMID:24978862

Dem?r, Kenan; Avc?, Ahmet; Y?lmaz, Sema; Dem?r, Tar?k; Ersecg?n, Ahmet; Altunkeser, Bulent Behlul

2014-08-01

48

Prevalence and Prognostic Significance of Fragmented QRS Complex in Middle-Aged Subjects With and Without Clinical or Electrocardiographic Evidence of Cardiac Disease.  

PubMed

We wanted to evaluate the prevalence and prognostic value of the fragmented QRS (fQRS) complex, defined as changes in QRS morphology with various RSR'-patterns in 12-lead electrocardiogram (ECG) in a middle-aged general population. We evaluated the 12-lead ECGs of 10,904 Finnish middle-aged subjects (52% men, mean age 44 ± 8.5 years) with (n = 2,543) and without (n = 8,361) an evidence of cardiac disease drawn from general population and followed them for 30 ± 11 years. Fragmentation of the QRS complex was defined as various RSR'-patterns in at least 2 consecutive leads within the same territory (inferior II, III, aVF; lateral I, aVL, V4 to V6; anterior V1 to V3). Primary end points were death from any cause, cardiac, and arrhythmic deaths. In the total population, fQRS was present in 19.7% (n = 2,147) of subjects, including 15.7% (n = 1714) in inferior leads, 0.8% (n = 84) in lateral leads, and 2.9% (n = 314) in anterior leads. Fragmentation was not associated with increased mortality in subjects without a known cardiac disease. However, fQRS observed in lateral leads in subjects with an evidence of cardiac disease was associated with an increased risk of all-cause (p = 0.001), cardiac (p = 0.001), and arrhythmic (p = 0.004) mortalities. In conclusion, fQRS reflecting minor intraventricular conduction defect is a common finding, especially in the inferior leads, but it is not a sign of increased risk of mortality in subjects without a known cardiac disease. Lateral fQRS, which is less commonly observed in the ECG, is associated with a worse outcome in patients with a known cardiac disease. PMID:24819902

Terho, Henri K; Tikkanen, Jani T; Junttila, Juhani M; Anttonen, Olli; Kenttä, Tuomas V; Aro, Aapo L; Kerola, Tuomas; Rissanen, Harri A; Reunanen, Antti; Huikuri, Heikki V

2014-07-01

49

Fragmented QRS complexes-a novel but underutilized electrocardiograhic marker of heart disease.  

PubMed

The electrocardiogram is the mainstay approach for diagnosing a myocardial infarction (MI). The diagnosis of an old MI and the identification of myocardial scar via the electrocardiogram are difficult because there are no other specific signs for a non-Q-wave MI. In this article, we will review the fragmented QRS and its role in identifying myocardial scar and depolarization abnormalities in patients with coronary artery disease. PMID:24240545

Fares, Hassan; Heist, Kevin; Lavie, Carl J; Kumbala, Damodar; Ventura, Hector; Meadows, Renee; Carter, William; Deitelzweig, Steven; Ray, Indranill Basu

2013-12-01

50

Influence of QRS complex detection errors on entropy algorithms. Application to heart rate variability discrimination.  

PubMed

Signal entropy measures such as approximate entropy (ApEn) and sample entropy (SampEn) are widely used in heart rate variability (HRV) analysis and biomedical research. In this article, we analyze the influence of QRS detection errors on HRV results based on signal entropy measures. Specifically, we study the influence that QRS detection errors have on the discrimination power of ApEn and SampEn using the cardiac arrhythmia suppression trial (CAST) database. The experiments assessed the discrimination capability of ApEn and SampEn under different levels of QRS detection errors. The results demonstrate that these measures are sensitive to the presence of ectopic peaks: from a successful classification rate of 100%, down to a 75% when spikes are present. The discriminating capability of the metrics degraded as the number of misdetections increased. For an error rate of 2% the segmentation failed in a 12.5% of the experiments, whereas for a 5% rate, it failed in a 25%. PMID:23246085

Molina-Picó, Antonio; Cuesta-Frau, David; Miró-Martínez, Pau; Oltra-Crespo, Sandra; Aboy, Mateo

2013-04-01

51

A multi-step method with signal quality assessment and fine-tuning procedure to locate maternal and fetal QRS complexes from abdominal ECG recordings.  

PubMed

Non-invasive monitoring of fetal electrocardiogram (fECG) plays an important role in detecting and diagnosing fetal diseases. This study aimed to develop a multi-step method for locating both maternal and fetal QRS complexes from abdominal ECG (aECG) recordings. The proposed method included four major steps: abdominal ECG pre-processing, maternal QRS complex locating, maternal ECG cancellation and fetal QRS complex locating. Signal quality assessment (SQA) and fine-tuning for maternal ECG (FTM) were implemented in the first and third steps, respectively. The method was then evaluated using 75 non-invasive 4-channel aECG recordings provided by the PhysioNet/Computing in Cardiology Challenge 2013. The F1 measure, which is a new index introduced by Behar et al (2013 Proc. Comput. Cardiol. 40 297-300), was used to assess the locating accuracy. The other two indices, mean squared error of heart rate (MSE_HR) between the fetal HR signals estimated from the reference and our method (MSE_HR in bpm(2)) and root mean squared difference between the corresponding fetal RR intervals (MSE_RR in ms) were also used to assess the locating accuracy. Overall, for the maternal QRS complex, the F1 measure was 98.4% from the method without the implementation of SQA, and it was improved to 99.8% with SQA. For the fetal QRS complex, the F1 measure, MSE_HR and MSE_RR were 84.9%, 185.6?bpm(2) and 19.4?ms for the method without both SQA and FTM procedures. They were improved to 93.9%, 47.5?bpm(2) and 7.6?ms with both SQA and FTM procedures. These improvements were observed from each individual subject. It can be concluded that implementing both SQA and FTM procedures could achieve better performance for locating both maternal and fetal QRS complexes. PMID:25069817

Liu, Chengyu; Li, Peng; Di Maria, Costanzo; Zhao, Lina; Zhang, Henggui; Chen, Zhiqing

2014-08-01

52

Comparison of the Relation Between Left Ventricular Anatomy and QRS Duration in Patients With Cardiomyopathy With Versus Without Left Bundle Branch Block.  

PubMed

QRS duration (QRSd) is used to diagnose left bundle branch block (LBBB) and is important to determine cardiac resynchronization therapy eligibility. The same QRSd thresholds established decades ago are used for all patients. However, significant interpatient variability of normal QRSd exists, and individualized QRSd thresholds might improve diagnosis and intervention strategies. Previous work reported left ventricular (LV) mass and papillary muscle location predicted QRSd in healthy subjects, but the relation in diseased ventricles is unknown. The aim of the present study was to determine the association between LV anatomy and QRSd in patients with cardiomyopathy. Patients referred for primary prevention implantable defibrillators (n = 166) received cardiac magnetic resonance imaging, and those with normal conduction (without bundle branch or fascicular block) and LBBB were studied. The LV mass, length, internal diameter, LV end-diastolic volume, septal and lateral wall thicknesses, and papillary muscle location were measured. In patients with normal conduction, LV length (r = 0.35, p <0.001), mass (r = 0.32, p <0.001), diameter (r = 0.20, p = 0.03), and septal wall thickness (r = 0.20, p = 0.03) had positive correlations with QRSd. In patients with LBBB, LV length (r = 0.32, p = 0.03), mass (r = 0.39, p = 0.01), diameter (r = 0.34, p = 0.02), and LV end-diastolic volume (r = 0.32, p = 0.04) had positive correlations with QRSd. Contrary to previous studies in healthy subjects, papillary muscle angle (location) was not associated with QRSd in cardiomyopathy patients with normal conduction or LBBB. In conclusion, increasing LV anatomical measurements were associated with increasing QRSd in patients with cardiomyopathy. Future work should investigate the use of LV anatomical measurements in developing individualized QRSd thresholds for diagnosing conduction abnormalities such as LBBB and identifying candidates for cardiac resynchronization therapy. PMID:24698465

Chan, Dulciana D; Wu, Katherine C; Loring, Zak; Galeotti, Loriano; Gerstenblith, Gary; Tomaselli, Gordon; Weiss, Robert G; Wagner, Galen S; Strauss, David G

2014-05-15

53

Wavelets for QRS detection  

Microsoft Academic Search

This paper examines the use of different wavelet functions for QRS complex detection in ECG. Wavelets provide time and frequency\\u000a analysis simultaneously and offer flexibility with a number of wavelet functions with different properties available. This\\u000a research has examined wavelet functions with different properties to determine the effects of orthogonality and time\\/ frequency\\u000a compactness of the wavelet on the ability

H. A. N. Dinh; D. K. Kumar; N. D. Pah; P. Burton

2001-01-01

54

QRS detection using morphological and rhythm information  

Microsoft Academic Search

An approach has been developed using artificial neural networks to detect QRS complexes within an ambulatory ECG signal. The method employs the use of an artificial neural network classifier to recognise the morphology of a QRS complex based on amplitude and derivative features. The feature vectors are derived from a representative annotated ECG trace and are used in the formulation

A. I. Rasiah; R. Togneri; Y. Attikiouzel

1995-01-01

55

Adaptive threshold QRS detection algorithm for ambulatory ECG  

Microsoft Academic Search

The authors have developed an algorithm for detection of QRS complexes of ambulatory electrocardiogram (ECG) signals. The threshold, which is obtained from a distribution function of the amplitude of the filtered ECG signal, changes with time, adapting to changes in the QRS morphology, levels of noise, and artifacts. The threshold extracts the period which include the QRS complex, and then

K. Akazawa; K. Motoda; A. Sasamori; T. Ishizawa; E. Harasawa

1991-01-01

56

QRS detection based on wavelet coefficients.  

PubMed

Electrocardiogram (ECG) signal processing and analysis provide crucial information about functional status of the heart. The QRS complex represents the most important component within the ECG signal. Its detection is the first step of all kinds of automatic feature extraction. QRS detector must be able to detect a large number of different QRS morphologies. This paper examines the use of wavelet detail coefficients for the accurate detection of different QRS morphologies in ECG. Our method is based on the power spectrum of QRS complexes in different energy levels since it differs from normal beats to abnormal ones. This property is used to discriminate between true beats (normal and abnormal) and false beats. Significant performance enhancement is observed when the proposed approach is tested with the MIT-BIH arrhythmia database (MITDB). The obtained results show a sensitivity of 99.64% and a positive predictivity of 99.82%. PMID:22296976

Zidelmal, Zahia; Amirou, Ahmed; Adnane, Mourad; Belouchrani, Adel

2012-09-01

57

A QRS detection algorithm  

Microsoft Academic Search

In this article we present the choices that the designers of any QRS detector must make and explain the constraints we adopted.\\u000a We outline the signal processing that precedes and the beat analysis that follows QRS detection in our single-channel, arrhythmia-monitoring\\u000a algorithm and then expound the QRS detection algorithm in detail. Finally, we present the results of a QRS detector

A. Dean Forbes; Holly B. Jimison

1987-01-01

58

A simple real-time QRS detection algorithm  

Microsoft Academic Search

A simple algorithm using topological mapping has been developed for a real-time detection of the QRS complexes of ECG signals. As a measure of QRS complex energy, the authors used topological mapping from one dimensional sampled ECG signals to two dimensional vectors. To describe a change of curvature, the authors derive modified spatial velocity (MSV), from MSV the authors can

Jeongwhan Lee; Keesam Jeong; Jiyoung Yoon; Myoungho Lee

1996-01-01

59

QRS Slopes for Detection and Characterization of Myocardial Ischemia  

Microsoft Academic Search

In this study, the upward (IUS) and downward (IDS) slopes of the QRS complex are proposed as indices for quantifying ischemia-induced electrocardiogram (ECG) changes. Using ECG recordings acquired before and during percutaneous transluminal coronary angioplasty (PTCA), it is found that the QRS slopes are considerably less steep during artery occlusion, in particular for IDS. With respect to ischemia detection, the

Esther Pueyo; Leif Sörnmo; Pablo Laguna

2008-01-01

60

Neural-network-based adaptive matched filtering for QRS detection  

Microsoft Academic Search

The authors have developed an adaptive matched filtering algorithm based upon an artificial neural network (ANN) for QRS detection. They use an ANN adaptive whitening filter to model the lower frequencies of the electrocardiogram (ECG) which are inherently nonlinear and nonstationary. The residual signal which contains mostly higher frequency QRS complex energy is then passed through a linear matched filter

Qiuzhen Xue; Yu Hen Hu; Willis J. Tompkins

1992-01-01

61

Performance of three QRS detection algorithms during sleep: a comparative study  

Microsoft Academic Search

A comparison of the performance of three QRS detectors used in the analysis of electrocardiogram (ECG) during sleep is presented in this paper. Two widely used QRS detection algorithms based on digital filtering (DF) are compared with a newly introduced one, based on higher-order statistics (HOS). The percentage of QRS complexes failed detection along with the number of false positives

Leontios J. Hadjileontiadis; Kostas I. Panoulas; T. Penzel; Stavros M. Panas

2001-01-01

62

A Method of Continuous Wavelet Transform for QRS Wave Detection in ECG Signal  

Microsoft Academic Search

Reliable detection of QRS is not only the important basis for diagnosis of arrhythmia, but also the further analysis of other detail ECG information can be defined through the detected QRS wave. According to the relationship of singular point, Lipschitz exponent and wavelet transform maximum modulus, a method called zero-crossings is introduced to detect QRS complex waves. With properly selected

Qi Haibing; Liu Xiongfei; Pan Chao

2010-01-01

63

Development of a fuzzy rule-based QRS detection algorithm for fetal and maternal heart rate monitoring  

Microsoft Academic Search

Signal processing problems related to abdominal-lead fetal ECG include the cancellation of the maternal QRS complex, signal enhancement of the fetal QRS complex and detection of the presence of a fetal R-wave to compute the fetal heart rate. This paper describes an improved scheme for detecting the presence of the QRS complexes from the enhanced fetal ECG signal obtained by

K. A. K. Azad; Z. M. Darus; M. A. M. Ali

1998-01-01

64

Association of QRS duration with left ventricular structure and function and risk of heart failure in middle-aged and older adults: the Multi-Ethnic Study of Atherosclerosis (MESA)  

PubMed Central

Aims Prolonged QRS duration (QRSd) on the electrocardiogram (ECG) has been associated with cardiac structural and functional abnormalities by echocardiography and an increased risk of heart failure (HF). Data are sparse on these relationships in middle-aged and elderly individuals free of baseline cardiovascular disease with respect to cardiac magnetic resonance imaging (MRI). We sought to determine whether QRSd is associated with incident HF and measures of cardiac structure and function by cardiac MRI. Methods and results We analysed baseline ECGs in the Multi-Ethnic Study of Atherosclerosis (MESA) to determine whether QRSd >100 ms was associated with incident HF. We adjusted for demographic and clinical risk factors, as well as MRI measures of left ventricular (LV) structure and function. Among 4591 eligible participants (51% women; 39% white; mean age 61 years), 75 developed incident HF over a mean follow-up of 7.1 years. QRSd >100 ms was significantly associated with MRI measures of cardiac structure and function, as well as incident HF, even after adjustment for demographic covariates [hazard ratio (HR) 2.10, 95% confidence interval (CI) 1.29–3.42; P = 0.003] and clinical risk factors (HR 1.86, 95% CI 1.14–3.03; P = 0.01). With further adjustment for individual LV structural measures, findings were attenuated to non-significance. Separate adjustment for LV functional measures yielded only mild attenuation. Conclusion In middle-aged and older adults without cardiovascular disease, a QRSd >100 ms was significantly associated with incident HF. After adjustment for LV structural measures, the association was attenuated to non-significance, suggesting that prolonged QRSd is potentially a useful marker of LV structure that may predispose to HF risk.

Ilkhanoff, Leonard; Liu, Kiang; Ning, Hongyan; Nazarian, Saman; Bluemke, David A.; Soliman, Elsayed Z.; Lloyd-Jones, Donald M.

2012-01-01

65

The principles of software QRS detection  

Microsoft Academic Search

The QRS complex is the most striking waveform within the electrocardiogram (ECG). Since it reflects the electrical activity within the heart during the ventricular contraction, the time of its occurrence as well as its shape provide much information about the current state of the heart. Due to its characteristic shape it serves as the basis for the automated determination of

Bert-Uwe Köhler; Carsten Hennig; Reinhold Orglmeister

2002-01-01

66

The timing of onset of mechanical systole and diastole in reference to the QRS-T complex: a study to determine performance criteria for a non-invasive diastolic timed vibration massage system in treatment of potentially unstable cardiac disorders.  

PubMed

Our institution is in development of a low frequency, non-invasive Diastolic Timed Vibrator (DTV) for use in emergency treatment of ST Elevation Myocardial Infarction (STEMI). It is preferable to avoid vibration emissions during the IsoVolumetric Contraction Period (IVCP) and at least the majority of mechanical systole thereafter, as systolic vibration may cause a negative inotropic effect in the ischemic heart. Furthermore diastolic vibration should preferably include the IsoVolumetric Relaxation Period (IVRP) which has been shown in clinical studies to improve cardiac performance and enhance coronary flow. Electrocardiographic (ECG) monitoring can be used to enable diastolic tracking, however, the timing of the phases of the cardiac cycle in relation to the ECG waveform must first be verified. The objective of this study was therefore to determine timing of onset of mechanical systole and diastole in reference to the QRS-T Complex. One hundred and twenty-three adult echocardiographic studies were assessed for the point of mitral and aortic valve closure in relation to the QRS complex and T wave in a representative population. We found that onset of mechanical systole occurred on and usually shortly after the peak of a first dominant QRS complex deflection, and onset of diastole occurred at the earliest on and most commonly beyond the peak or midpoint of the T wave. A DTV should ideally be able to stop vibrating on or before the peak of the first dominant deflection of a QRS complex, and begin vibrating near the peak of the T wave. Given early detection of ventricular depolarization can occur 10-20 ms prior to R wave peak, it is proposed that a DTV should preferably be able to stop vibrating within 10 ms of a triggered stop command. Onset of vibration during peak of T wave could be approximated by a rate adapted Q-T interval regression equation, and then fine tuned by manual adjustment during therapy. PMID:21113800

Gill, Harjit; Hoffmann, Andrew

2010-12-01

67

A QRS detection algorithm for discriminating artifacts in ECG records  

Microsoft Academic Search

A simple and efficient algorithm has been developed to detect QRS complexes at high speed (approximately 32 times real-time speed) from the single-channel digitized ECG (electrocardiogram) data records. This algorithm discriminate QRS complexes against various artifacts, including those due to tape-recorder amplifier saturation. Attenuation of noise (60-Hz power-line frequency) is obtained in a systematic way by a suitable differentiation procedure.

Murari L. Kejariwal

1989-01-01

68

An automated algorithm for online detection of fragmented QRS and identification of its various morphologies.  

PubMed

Fragmented QRS (f-QRS) has been proven to be an efficient biomarker for several diseases, including remote and acute myocardial infarction, cardiac sarcoidosis, non-ischaemic cardiomyopathy, etc. It has also been shown to have higher sensitivity and/or specificity values than the conventional markers (e.g. Q-wave, ST-elevation, etc.) which may even regress or disappear with time. Patients with such diseases have to undergo expensive and sometimes invasive tests for diagnosis. Automated detection of f-QRS followed by identification of its various morphologies in addition to the conventional ECG feature (e.g. P, QRS, T amplitude and duration, etc.) extraction will lead to a more reliable diagnosis, therapy and disease prognosis than the state-of-the-art approaches and thereby will be of significant clinical importance for both hospital-based and emerging remote health monitoring environments as well as for implanted ICD devices. An automated algorithm for detection of f-QRS from the ECG and identification of its various morphologies is proposed in this work which, to the best of our knowledge, is the first work of its kind. Using our recently proposed time-domain morphology and gradient-based ECG feature extraction algorithm, the QRS complex is extracted and discrete wavelet transform (DWT) with one level of decomposition, using the 'Haar' wavelet, is applied on it to detect the presence of fragmentation. Detailed DWT coefficients were observed to hypothesize the postulates of detection of all types of morphologies as reported in the literature. To model and verify the algorithm, PhysioNet's PTB database was used. Forty patients were randomly selected from the database and their ECG were examined by two experienced cardiologists and the results were compared with those obtained from the algorithm. Out of 40 patients, 31 were considered appropriate for comparison by two cardiologists, and it is shown that 334 out of 372 (89.8%) leads from the chosen 31 patients complied favourably with our proposed algorithm. The sensitivity and specificity values obtained for the detection of f-QRS were 0.897 and 0.899, respectively. Automation will speed up the detection of fragmentation, reducing the human error involved and will allow it to be implemented for hospital-based remote monitoring and ICD devices. PMID:24132202

Maheshwari, Sidharth; Acharyya, Amit; Puddu, Paolo Emilio; Mazomenos, Evangelos B; Leekha, Gourav; Maharatna, Koushik; Schiariti, Michele

2013-12-01

69

QRS alterations in body surface potential distributions during percutaneous transluminal coronary angioplasty in single-vessel disease.  

PubMed

Body surface QRS potentials were recorded with 63 chest leads in 20 patients with proximal single-vessel disease located on either the left anterior descending coronary artery (n = 10), the right coronary artery (n = 6), or the left circumflex coronary artery (n = 4) before, during, and after percutaneous transluminal coronary angioplasty. In each case, three consecutive inflations of relatively short duration (37 +/- 14 seconds) were carried out. Electrical activity was displayed as unipolar electrograms and body surface potential maps. The total QRS complex duration decreased in 14 of the 20 patients. Focal conduction disturbances were observed in six cases; all six had left anterior descending coronary artery occlusion and two were also accompanied by a clear shortening of the right epicardial breakthrough time. In these two cases, an initial activation loss seemed to be characteristic, whereas in the other four cases, a rather diffuse slowing of intraventricular conduction, especially during the terminal portion of the QRS, could be observed. Individual and group mean isointegral difference body surface potential maps (during-minus-before dilation) were considered valuable for the interpretation of localized changes in intraventricular conduction during percutaneous transluminal coronary angioplasty, and their individual variations could, at least partly, be explained by the presence or absence of collateral circulation. Two different hypotheses are suggested to account for the QRS complex shortening observed during short-term myocardial ischemic injury: (1) coronary artery occlusion delayed activation of the portion of the septal region that is normally activated early during the QRS, and/or (2) coronary artery occlusion increased the speed of propagation within the ventricles. Both of these hypotheses are discussed in light of earlier clinical and experimental results. PMID:7815009

Préda, I; Nadeau, R; Savard, P; Hamel, D; Palisaitis, D; Shenasa, M; Nasmith, J

1994-10-01

70

A New QRS Detection Method Using Wavelets and Artificial Neural Networks  

Microsoft Academic Search

We present a new method for detection and classification of QRS complexes in ECG signals using continuous wavelets and neural\\u000a networks. Our wavelet method consists of four wavelet basis functions that are suitable in detection of QRS complexes within\\u000a different QRS morphologies in the signal and thresholding technique for denoising and feature extraction. The results demonstrate\\u000a that the proposed method

Berdakh Abibullaev; Hee Don Seo

71

Development of QRS detection algorithm designed for wearable cardiorespiratory system  

Microsoft Academic Search

An in-home sleep monitoring system was developed previously in our laboratory for monitoring electrocardiography (ECG) and respiratory signals. However, the ECG signal acquired with this system is prone to high-grade noise caused by motion artifact. Since the detection of the QRS complexes with high accuracy is very important in a computer-based analysis of the ECG, a high accuracy QRS detection

Mourad Adnane; Zhongwei Jiang; Samjin Choi

2009-01-01

72

An innovative approach of QRS segmentation based on first-derivative, Hilbert and Wavelet Transforms.  

PubMed

The QRS detection and segmentation processes constitute the first stages of a greater process, e.g., electrocardiogram (ECG) feature extraction. Their accuracy is a prerequisite to a satisfactory performance of the P and T wave segmentation, and also to the reliability of the heart rate variability analysis. This work presents an innovative approach of QRS detection and segmentation and the detailed results of the proposed algorithm based on First-Derivative, Hilbert and Wavelet Transforms, adaptive threshold and an approach of surface indicator. The method combines the adaptive threshold, Hilbert and Wavelet Transforms techniques, avoiding the whole ECG signal preprocessing. After each QRS detection, the computation of an indicator related to the area covered by the QRS complex envelope provides the detection of the QRS onset and offset. The QRS detection proposed technique is evaluated based on the well-known MIT-BIH Arrhythmia and QT databases, obtaining the average sensitivity of 99.15% and the positive predictability of 99.18% for the first database, and 99.75% and 99.65%, respectively, for the second one. The QRS segmentation approach is evaluated on the annotated QT database with the average segmentation errors of 2.85±9.90ms and 2.83±12.26ms for QRS onset and offset, respectively. Those results demonstrate the accuracy of the developed algorithm for a wide variety of QRS morphology and the adaptation of the algorithm parameters to the existing QRS morphological variations within a single record. PMID:22226589

Madeiro, Joăo P V; Cortez, Paulo C; Marques, Joăo A L; Seisdedos, Carlos R V; Sobrinho, Carlos R M R

2012-11-01

73

Wavelet transform and neural-network-based adaptive filtering for QRS detection  

Microsoft Academic Search

This paper presents an adaptive neural-network-based ECG signal filtering, and a wavelet transform based QRS detection method. An adaptive whitening filter is modeling the lower frequencies of the ECG, which are inherently nonlinear and nonstationary. In this way the estimation error will consist of the QRS wave. The wavelet-transform-based QRS detection method will determine the position of these complexes and

S. M. Szilagyi; L. Szilagyi

2000-01-01

74

Accuracy of QRS detection in relation to the analysis of high-frequency components in the electrocardiogram  

Microsoft Academic Search

The detection of high-frequency components in the QRS complex by means of coherent signal averaging is affected by inaccuracy\\u000a in the time reference. Jitter of the time reference or trigger, which is derived from the low-frequency QRS complex, will\\u000a be caused by the noise in the QRS complex. A theory is developed by which the trigger jitter can be predicted

G. J. H. Uijen; J. P. C. de Weerd; A. J. H. Vendrik

1979-01-01

75

QRS detection by wavelet transform  

Microsoft Academic Search

In this paper, the wavelet transform is used for QW detection. Some detection strategies are applied to decrease the fake detection succes~fully. The correct QRS detection rate reaches to 99. 8% in the experiment with the bflT\\/BLH arrhythmia database.

Cuiwei Li; Chongxun Zheng

1993-01-01

76

Absence and Resolution of Fragmented QRS Predict Reversible Myocardial Ischemia With Higher Probability of ST Segment Resolution in Patients With ST Segment Elevation Myocardial Infarction  

PubMed Central

Background and Objectives Fragmented QRS complexes (fQRS) are associated with increased morbidity and mortality. The causative relationship between fQRS and cardiac fibrosis has been shown, but whether the presence and the number of fQRS on admission of electrocardiogram (ECG) predicts ST segment resolution in patients undergoing primary percutaneous coronary intervention (p-PCI) has not been investigated until now. Subjects and Methods This study included one hundred and eighty-four consecutive patients with ST elevation myocardial infarction (STEMI) who underwent p-PCI. The presence or absence of fQRS on pre and post-PCI ECG and their relation with myocardial infarction and reperfusion parameters were investigated. Results Patients with fQRS on admission of ECG or newly developed fQRS after p-PCI had increased inflammatory markers, higher cardiac enzyme levels, increased pain to balloon time, prolonged QRS time, more extended coronary involvement and more frequent Q waves on ECG in comparison to patients with absence or resolved fQRS. The presence and higher number of fQRS on admission or post-PCI ECGs were significantly related with low percent of ST resolution and myocardial reperfusion parameters. The area under the receiver operating characteristics curve values for the presence and number of fQRS to detect Thrombolysis in Myocardial Infarction Blush Grade 0 and 1, were 0.682 and 0.703. Conclusion In our study, fQRS was significantly related to infarction and myocardial reperfusion parameters before and after p-PCI. Successful myocardial reperfusion by p-PCI caused the reduction in number of fQRS and QRS time with higher ST resolution. fQRS may be useful in identifying the patients at higher cardiac risk with increased ischemic jeopardized or infarcted myocardium, and persistent or newly developed fQRS may predict low percent of ST segment resolution in patients undergoing p-PCI.

Cetin, Mustafa; Kiris, Tuncay; Erdogan, Turan; Canga, Aytun; Durakoglugil, Murtaza Emre; Cicek, Yuksel; Dogan, Sitki; Satiroglu, Omer

2012-01-01

77

Factors affecting the duration effect in pitch perception for unresolved complex tones  

NASA Astrophysics Data System (ADS)

Previous research has shown that fundamental frequency (F0) discrimination thresholds for complex tones containing unresolved harmonics decrease as the duration of the tone increases [White and Plack, J. Acoust. Soc. Am. 103, 2051-2063 (1998)]. In this paper F0 discrimination was measured as a function of duration for complexes with F0s of 62.5, 125, and 250 Hz, bandpass filtered into two spectral regions (2750-3750 and 5500-7500 Hz). The harmonics were summed either in sine phase (SINE) or with alternating sine-cosine phase (ALT), which affects the envelope of the waveform and the pitch of the complex. Tone duration was 20, 40, 80, and 160 ms. The improvement in F0 discrimination with duration increased with decreasing F0. When harmonics where spectrally filtered between 2750 and 3750 Hz, for complexes with an F0 of 62.5 Hz, F0 discrimination thresholds decreased from approximately 30% for a 20-ms tone to approximately 3% for a 160-ms tone. For complexes with an F0 of 250 Hz, thresholds decreased from 3% for a 20-ms tone to 1% for a 160-ms tone: a lower envelope repetition rate led to a larger change in performance with increasing duration. The phase manipulation also affected the size of the duration effect, in that the effect was less for an ALT complex compared to a SINE complex with the same F0, consistent with the change in envelope repetition rate. Overall, the results suggest that for unresolved complex tones it is primarily envelope repetition rate, not spectral region, that determines both the F0 discrimination threshold and the size of the duration effect.

White, Louise J.; Plack, Christopher J.

2003-12-01

78

QRS morphology representation and noise estimation using the Karhunen-Loeve transform  

Microsoft Academic Search

The authors describe robust methods for deriving Karhunen-Loeve (KL) basis functions, which can be used to represent the QRS complex. Using a five-term KL expansion of a 200-ms interval, which includes the QRS complex and part of the ST segment, one can represent morphology on two simultaneous ECG (electrocardiographic) leads with sufficient fidelity for beat classification. The residual error of

George B. Moody; Roger G. Mark

1989-01-01

79

A comparison of the noise sensitivity of nine QRS detection algorithms  

Microsoft Academic Search

The noise sensitivities of nine different QRS detection algorithms were measured for a normal, single-channel, lead-II, synthesized ECG corrupted with five different types of synthesized noise: electromyographic interference, 60-Hz power line interference, baseline drift due to respiration, abrupt baseline shift, and a composite noise constructed from all of the other noise types. The percentage of QRS complexes detected, the number

GARY M. FRIESEN; THOMAS C. JANNETT; MANAL AFIFY JADALLAH; STANFORD L. YATES; STEPHEN R. QUINT; H. TROY NAGLE

1990-01-01

80

Adaptive matched filtering for QRS detection  

Microsoft Academic Search

The authors have investigated the use of an adaptive filter to whiten the noise in the ECG (electrocardiogram) signal and adjust the matched filter response accordingly. They applied a simple QRS detection strategy to the filtered signal and evaluated the QRS detector with ECG data containing severe motion artifact and muscle noise. Preliminary results indicate that in the presence of

P. S. Hamilton; W. J. Tompkins

1988-01-01

81

QRS detection using S-Transform and Shannon energy.  

PubMed

This paper presents a novel method for QRS detection in electrocardiograms (ECG). It is based on the S-Transform, a new time frequency representation (TFR). The S-Transform provides frequency-dependent resolution while maintaining a direct relationship with the Fourier spectrum. We exploit the advantages of the S-Transform to isolate the QRS complexes in the time-frequency domain. Shannon energy of each obtained local spectrum is then computed in order to localize the R waves in the time domain. Significant performance enhancement is confirmed when the proposed approach is tested with the MIT-BIH arrhythmia database (MITDB). The obtained results show a sensitivity of 99.84%, a positive predictivity of 99.91% and an error rate of 0.25%. Furthermore, to be more convincing, the authors illustrated the detection parameters in the case of certain ECG segments with complicated patterns. PMID:24856322

Zidelmal, Z; Amirou, A; Ould-Abdeslam, D; Moukadem, A; Dieterlen, A

2014-08-01

82

COMPARATIVE STUDY OF QRS DETECTION IN SINGLE LEAD AND 12LEAD ECG BASED ON ENTROPY AND COMBINED ENTROPY CRITERIA USING SUPPORT VECTOR MACHINE  

Microsoft Academic Search

Application of Support Vector Machine (SVM) for QRS detection in single lead and 12-lead Electrocardiogram (ECG) using entropy and combined entropy criterion is presented in this paper. The ECG signal is filtered using digital filtering techniques to remove power line interference and base line wander. SVM is used as a classifier for detection of QRS complexes in ECG. Using the

S. S. Mehta; N. S. Lingayat

83

Increased omega complexity and decreased microstate duration in nonmedicated schizophrenic patients.  

PubMed

To explore brain functions in schizophrenic patients, the global analytic strategy of multichannel EEG was performed that combines measures of global complexity (Omega), total power (Sigma) and generalized frequency (Phi), and EEG microstate analysis was applied to multichannel EEG data for 24 nonmedicated patients and 24 healthy subjects. The patients had higher Omega and Sigma values, and lower Phi values compared with healthy subjects. Three topographical classes were obtained from all EEG data by EEG microstate analysis. The mean duration of one topographical class in the patients was shortened compared to healthy subjects. These results indicated looser cooperativity, or decreased connectivity of the active brain process and deviant brain information processing in schizophrenic patients. PMID:17199099

Irisawa, Satoshi; Isotani, Toshiaki; Yagyu, Takami; Morita, Sachi; Nishida, Keiichiro; Yamada, Keizo; Yoshimura, Masafumi; Okugawa, Gaku; Nobuhara, Kenji; Kinoshita, Toshihiko

2006-01-01

84

Complex H(sub alpha) Loop Activity in a Long Duration Flare  

NASA Technical Reports Server (NTRS)

A long duration Bare was observed in the active region NOAA 6555 on March 23, 1991 at a location of low magnetic shear. This flare displayed complex H(sub alpha) loop activity during the decay phase. Initially, there were a few long loops orientated at an angle of about 45 degree with the east-west axis followed by the appearance of east-west axis. This configuration was aligned shorter loops. By using different magnetic field models, we have extrapolated the photospheric magnetogram.9 to the chromospheric heights. The magnetic field lines computed by using the potential field model correspond to most of the observed H. loops. In this paper, we report the analysis of high resolution chromospheric observations of the event and describe a possible scenario for the post-flare loop activity.

Debi Prasad, Choudhary; Gary, G. Allen; Ambastha, Ashok K.

1998-01-01

85

Month-to-Month and Year-to-Year Reproducibility of High Frequency QRS ECG signals.  

National Technical Information Service (NTIS)

High frequency (HF) electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized....

N. Batdorf A. H. Feiveson T. T. Schlegel

2006-01-01

86

QRS Detection for Pacemakers in a Noisy Environment Using a Time Lagged Artificial Neural Network  

Microsoft Academic Search

A time lagged feedforward artificial neural network (TLFN) is used to detect QRS complexes for pacemakers in a noisy environment. The TLFN reduces the influence of lower frequencies in the invasive electrogram (EG) signals, such as the P and T waves. The TLFN output is then subjected to matched filtering with a dynamically updated impulse response. Detector performance is studied

J. Neves Rodrigues; V. Owall; L. Sonzino

87

A real-time simulated QRS detection system constructed using wavelet filtering technique  

Microsoft Academic Search

Electrocardiography (ECG) signals analysis is a very important step in the detection of some of the electrophysiological abnormalities that distinguish patients with and without sustained late potential problems. Unfortunately, approaches developed so far, both in time and frequency domain of the QRS complex suffer from a relatively low positive-predictive accuracy. This underscores the requirement to improve methods. In this study,

Gulden Kokturk

1998-01-01

88

Nonlinear transforms of ECG signals for digital QRS detection: a quantitative analysis  

Microsoft Academic Search

A class of algorithms has been developed which detects QRS complexes in the electrocardiogram (ECG). The algorithms employ nonlinear transforms derived from multiplication of backward differences (MOBD). The algorithms are evaluated with the American Heart Association ECG database, and comparisons are made with the algorithms reported by Okada (1979) and by Hamilton and Tompkins (1986). The MOBD algorithms provide a

Seth Suppappola; Ying Sun

1994-01-01

89

A Real Time QRS Detection Using Delay-Coordinate Mapping for the Microcontroller Implementation  

Microsoft Academic Search

In this article, we propose a new algorithm using the characteristics of reconstructed phase portraits by delay-coordinate mapping utilizing lag rotundity for a real-time detection of QRS complexes in ECG signals. In reconstructing phase portrait the mapping parameters, time delay, and mapping dimension play important roles in shaping of portraits drawn in a new dimensional space. Experimentally, the optimal mapping

Jeong-Whan Lee; Kyeong-Seop Kim; Bongsoo Lee; Byungchae Lee; Myoung-Ho Lee

2002-01-01

90

Robust and computational efficient QRS detection  

Microsoft Academic Search

A QRS detection algorithm has been developed based on a multivariate model. It included three normalized measures-amplitude, first difference and spatial frequency. The terms are combined in a weighted sum to generate an indicator variable that is then compared to a detection threshold. An FIR band-pass filter, consisting of a cascaded series of running medians and means prefiltered the raw

Alan B. Bond; E. C. Greco; R. Bowser; N. H. Kadri

1993-01-01

91

Integrate and fire pulse train automaton for QRS detection.  

PubMed

Monitoring heart activity from electrocardiograms (ECG) is crucial to avoid unnecessary fatalities; therefore, detection of QRS complex is fundamental to automated ECG monitoring. Continuous, portable 24/7 ECG monitoring requires wireless technology with constraints on power, bandwidth, area, and resolution. In order to provide continuous remote monitoring of patients and fast transmission of data to medical personnel for instantaneous intervention, we propose a methodology that converts analog inputs into pulses for ultralow power implementation. The signal encoding scheme is the time-based integrate and fire (IF) sampler from which a set of signal descriptors in the pulse domain are proposed. Furthermore, a logical decision rule for QRS detection based on morphological checking is derived. The proposed decision logic depends exclusively on relational and logical operators resulting in ultrafast recognition and can be implemented using combinatorial logic hardware to guarantee power consumption orders of magnitude lower than any microprocessor device. The algorithm was evaluated using the MIT-BIH arrhythmia database and results show that our algorithm performance is comparable to the state-of-the art software-based detection. PMID:24107919

Nallathambi, Gabriel; Príncipe, José C

2014-02-01

92

Variation in canopy duration in the perennial biofuel crop Miscanthus reveals complex associations with yield.  

PubMed

Energy crops can provide a sustainable source of power and fuels, and mitigate the negative effects of CO2 emissions associated with fossil fuel use. Miscanthus is a perennial C4 energy crop capable of producing large biomass yields whilst requiring low levels of input. Miscanthus is largely unimproved and therefore there could be significant opportunities to increase yield. Further increases in yield will improve the economics, energy balance, and carbon mitigation of the crop, as well as reducing land-take. One strategy to increase yield in Miscanthus is to maximize the light captured through an extension of canopy duration. In this study, canopy duration was compared among a diverse collection of 244 Miscanthus genotypes. Canopy duration was determined by calculating the number of days between canopy establishment and senescence. Yield was positively correlated with canopy duration. Earlier establishment and later senescence were also both separately correlated with higher yield. However, although genotypes with short canopy durations were low yielding, not all genotypes with long canopy durations were high yielding. Differences of yield between genotypes with long canopy durations were associated with variation in stem and leaf traits. Different methodologies to assess canopy duration traits were investigated, including visual assessment, image analysis, light interception, and different trait thresholds. The highest correlation coefficients were associated with later assessments of traits and the use of quantum sensors for canopy establishment. A model for trait optimization to enable yield improvement in Miscanthus and other bioenergy crops is discussed. PMID:23599277

Robson, Paul R H; Farrar, Kerrie; Gay, Alan P; Jensen, Elaine F; Clifton-Brown, John C; Donnison, Iain S

2013-05-01

93

Variation in canopy duration in the perennial biofuel crop Miscanthus reveals complex associations with yield  

PubMed Central

Energy crops can provide a sustainable source of power and fuels, and mitigate the negative effects of CO2 emissions associated with fossil fuel use. Miscanthus is a perennial C4 energy crop capable of producing large biomass yields whilst requiring low levels of input. Miscanthus is largely unimproved and therefore there could be significant opportunities to increase yield. Further increases in yield will improve the economics, energy balance, and carbon mitigation of the crop, as well as reducing land-take. One strategy to increase yield in Miscanthus is to maximize the light captured through an extension of canopy duration. In this study, canopy duration was compared among a diverse collection of 244 Miscanthus genotypes. Canopy duration was determined by calculating the number of days between canopy establishment and senescence. Yield was positively correlated with canopy duration. Earlier establishment and later senescence were also both separately correlated with higher yield. However, although genotypes with short canopy durations were low yielding, not all genotypes with long canopy durations were high yielding. Differences of yield between genotypes with long canopy durations were associated with variation in stem and leaf traits. Different methodologies to assess canopy duration traits were investigated, including visual assessment, image analysis, light interception, and different trait thresholds. The highest correlation coefficients were associated with later assessments of traits and the use of quantum sensors for canopy establishment. A model for trait optimization to enable yield improvement in Miscanthus and other bioenergy crops is discussed.

Robson, Paul R.H.

2013-01-01

94

QRS detection using a fuzzy neural network  

Microsoft Academic Search

We developed a QRS detection algorithm which uses a fuzzy neural network (FNN) to process lead II recordings of the ECG. We trained and tested our algorithm using the MIT\\/BIH arrhythmia database, and compared our results to existing algorithms. For tapes 100, 105 and 108, our FNN reduced the total number of combined false-positive and false-negative detections from 174 to

K. P. Cohen; W. J. Tompkins; A. Djohan; J. G. Webster; Y. H. Hu

1995-01-01

95

Products of the complex, long duration, AD 1305 rhyolitic eruption of Tarawera, New Zealand  

NASA Astrophysics Data System (ADS)

The youngest rhyolite eruption in New Zealand is the ~4 km3 (DRE) Kaharoa eruption episode from Tarawera volcano at ~1305AD. The complex eruption sequence occurred from seven magmatic vents which define an 8-km linear fissure across the volcano. The main events were: 1) phreatic blasts; 2) sub-plinian/plinian eruptions dispersing fallout over the northeastern North Island; 3) a rhyolite dome extrusion; 4) more sub-plinian fall units and pyroclastic flows, including at least two plinian fall units widespread to the NW over the North Island; 5)a final effusive phase producing three large lava domes. The total eruption duration is unknown, but the time required to extrude the lava domes indicates that it may have spanned several years to perhaps a decade. Collapse of the domes generated extensive block-and-ash flow deposits (BAFD). Four BAF fans were constructed during this time. The two largest fans are 1x108 m3 (N) and 5x107 m3 (SE), with the NW and W fans contributing 1x107 m3 and 4x106 m3 respectively. Unconfined BAFs within the SE fan reached a distance of 7.6 km from the dome margin. The N fan comprises a region of unconfined BAFD which reach 5.4 km from the source, and two valley-confined deposits that reach 9.2 km from source. Despite a complex internal stratigraphy, due in part to the irregular underlying topography, only three block and ash flow depositional units and associated ash cloud deposits may be identified in each of the two major fans. The block and ash flows of the Kaharoa eruptive episode are significantly larger and more widespread than many documented in the literature (Unzen, Japan; Soufriere Hills, Montserrat; Merapi, Indonesia; Mount St Helens, USA). Enhanced mobility of the Kaharoa block and ash flows is interpreted to be principally due to the large volumes of each collapse, involving substantial amounts of hot dome lava. BAF-related ash clouds and their deposits, which were so devastating at Unzen, may extend for up to 20 km from source. The potential for such voluminous and far-reaching BAFs and ash cloud deposits at Tarawera has clear implication for volcanic hazard assessment for future eruptions of this type.

Self, S.; Scutter, C. R.; Nairn, I. A.; Sahetapy-Engel, S. T.

2001-12-01

96

Revisiting QRS detection methodologies for portable, wearable, battery-operated, and wireless ECG systems.  

PubMed

Cardiovascular diseases are the number one cause of death worldwide. Currently, portable battery-operated systems such as mobile phones with wireless ECG sensors have the potential to be used in continuous cardiac function assessment that can be easily integrated into daily life. These portable point-of-care diagnostic systems can therefore help unveil and treat cardiovascular diseases. The basis for ECG analysis is a robust detection of the prominent QRS complex, as well as other ECG signal characteristics. However, it is not clear from the literature which ECG analysis algorithms are suited for an implementation on a mobile device. We investigate current QRS detection algorithms based on three assessment criteria: 1) robustness to noise, 2) parameter choice, and 3) numerical efficiency, in order to target a universal fast-robust detector. Furthermore, existing QRS detection algorithms may provide an acceptable solution only on small segments of ECG signals, within a certain amplitude range, or amid particular types of arrhythmia and/or noise. These issues are discussed in the context of a comparison with the most conventional algorithms, followed by future recommendations for developing reliable QRS detection schemes suitable for implementation on battery-operated mobile devices. PMID:24409290

Elgendi, Mohamed; Eskofier, Björn; Dokos, Socrates; Abbott, Derek

2014-01-01

97

Revisiting QRS Detection Methodologies for Portable, Wearable, Battery-Operated, and Wireless ECG Systems  

PubMed Central

Cardiovascular diseases are the number one cause of death worldwide. Currently, portable battery-operated systems such as mobile phones with wireless ECG sensors have the potential to be used in continuous cardiac function assessment that can be easily integrated into daily life. These portable point-of-care diagnostic systems can therefore help unveil and treat cardiovascular diseases. The basis for ECG analysis is a robust detection of the prominent QRS complex, as well as other ECG signal characteristics. However, it is not clear from the literature which ECG analysis algorithms are suited for an implementation on a mobile device. We investigate current QRS detection algorithms based on three assessment criteria: 1) robustness to noise, 2) parameter choice, and 3) numerical efficiency, in order to target a universal fast-robust detector. Furthermore, existing QRS detection algorithms may provide an acceptable solution only on small segments of ECG signals, within a certain amplitude range, or amid particular types of arrhythmia and/or noise. These issues are discussed in the context of a comparison with the most conventional algorithms, followed by future recommendations for developing reliable QRS detection schemes suitable for implementation on battery-operated mobile devices.

Elgendi, Mohamed; Eskofier, Bjorn; Dokos, Socrates; Abbott, Derek

2014-01-01

98

Missouri Quality Rating System: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Missouri's Quality Rating System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

99

Indiana Paths to Quality: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Indiana's Paths to Quality prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

100

Oregon Child Care Quality Indicators Program: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Oregon's Child Care Quality Indicators Program prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4)…

Child Trends, 2010

2010-01-01

101

North Carolina Star Rated License System: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of North Carolina's Star Rated License System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4)…

Child Trends, 2010

2010-01-01

102

Miami-Dade Quality Counts: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Miami-Dade's Quality Counts prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

103

Ohio Step Up to Quality: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Ohio's Step Up to Quality prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family…

Child Trends, 2010

2010-01-01

104

Illinois Quality Counts: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Illinois' Quality Counts prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family…

Child Trends, 2010

2010-01-01

105

Kentucky STARS for KIDS NOW: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Kentucky's STARS for KIDS NOW prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

106

Virginia Star Quality Initiative: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Virginia's Star Quality Initiative prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators…

Child Trends, 2010

2010-01-01

107

Iowa Child Care Quality Rating System: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Iowa's Child Care Quality Rating System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile is divided into the following categories: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family Child Care Programs;…

Child Trends, 2010

2010-01-01

108

Colorado Qualistar. QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Colorado's Qualistar prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family…

Child Trends, 2010

2010-01-01

109

Maine Quality for ME: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Maine's Quality for ME prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family…

Child Trends, 2010

2010-01-01

110

New Hampshire Quality Rating System: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of New Hampshire's Quality Rating System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4)…

Child Trends, 2010

2010-01-01

111

Delaware Stars for Early Success. QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Delaware's Stars for Early Success prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators…

Child Trends, 2010

2010-01-01

112

Palm Beach Quality Counts: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Palm Beach's Quality Counts prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

113

Pennsylvania Keystone STARS: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Pennsylvania's Keystone STARS prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for…

Child Trends, 2010

2010-01-01

114

Minnesota Parent Aware: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Minnesota's Parent Aware prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Indicators for Family…

Child Trends, 2010

2010-01-01

115

Mississippi Quality Step System: QRS Profile. The Child Care Quality Rating System (QRS)Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Mississippi's Quality Step System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4) Application…

Child Trends, 2010

2010-01-01

116

Interventricular delay interval optimization in cardiac resynchronization therapy guided by echocardiography versus guided by electrocardiographic QRS interval width.  

PubMed

Present devices for cardiac resynchronization therapy offer the possibility of tailoring the hemodynamic effect of biventricular pacing by optimization of the interventricular delay (VV) beyond atrioventricular (AV)-interval optimization. It was not yet defined whether a QRS width-based strategy may be a helpful tool for echocardiography for device programming. The aim of the study was to investigate the relation between VV-interval optimization guided by echocardiography and guided by QRS interval width. One hundred six patients with a cardiac resynchronization therapy device for > or =3 months were enrolled. All patients underwent echocardiographic AV and VV delay optimization. The AV interval was optimized according to the E wave-A wave (EA) interval and left ventricular filling time. At the optimal AV delay, VV optimization was performed by measuring the aortic velocity time integral at 5 different settings: simultaneous right and left ventricle output, left ventricle pre-excitation (left ventricle + 40 and 80 ms, respectively), and right ventricle pre-excitation (right ventricle + 40 and 80 ms, respectively). A 12-lead electrocardiogram was recorded and QRS duration was measured in the lead with the greatest QRS width. The electrocardiographic (ECG)-optimized VV interval was defined according to the narrowest achievable QRS interval among 5 VV intervals. The echocardiographic-optimized VV interval was left ventricle + 40 ms in 28 patients, left ventricle + 80 ms in 15 patients, simultaneous in 46 patients, right ventricle + 40 ms in 14 patients, and right ventricle + 80 ms in 3 patients. Significant concordance (kappa = 0.69, p <0.001) was found between the echocardiographic- and ECG-optimized VV interval. In conclusion, significant concordance appeared to exist during biventricular pacing between VV programming based on the shortest QRS interval at 12-lead ECG pacing and echocardiographic-guided VV-interval optimization. A combined ECG- and echocardiographic approach could be a less time-consuming solution in performing this operation. PMID:18993158

Bertini, Matteo; Ziacchi, Matteo; Biffi, Mauro; Martignani, Cristian; Saporito, Davide; Valzania, Cinzia; Diemberger, Igor; Cervi, Elena; Frisoni, Jessica; Sangiorgi, Diego; Branzi, Angelo; Boriani, Giuseppe

2008-11-15

117

Prosodic Planning: Effects of Phrasal Length and Complexity on Pause Duration  

PubMed Central

Research on pause duration has mainly focused on the impact of syntactic structure on the duration of pauses within an utterance and on the impact of syntax, discourse, and prosodic structure on the likelihood of pause occurrence. Relatively little is known about what factors play a role in determining the duration of pauses between utterances or phrases. Two experiments examining the effect of prosodic structure and phrase length on pause duration are reported. Subjects read sentences varying along the following parameters: a) the length in syllables of the intonational phrase preceding and following the pause, and b) the prosodic structure of the intonational phrase preceding and following the pause, specifically whether or not the intonational phrase branches into smaller phrases. In order to minimize variability due to speech rate and individual differences, speakers read sentences synchronously in dyads. The results showed a significant post-boundary effect of prosodic branching and significant pre- and post-boundary phrase length effects. The results are discussed in terms of production units.

Krivokapi, Jelena

2007-01-01

118

An Improved QRS Wave Group Detection Algorithm and Matlab Implementation  

NASA Astrophysics Data System (ADS)

This paper presents an algorithm using Matlab software to detect QRS wave group of MIT-BIH ECG database. First of all the noise in ECG be Butterworth filtered, and then analysis the ECG signal based on wavelet transform to detect the parameters of the principle of singularity, more accurate detection of the QRS wave group was achieved.

Zhang, Hongjun

119

Body Sensor Network Based Context Aware QRS Detection  

Microsoft Academic Search

In this paper, a body sensor network (BSN) based context aware QRS detection scheme is proposed. The algorithm uses the context information provided by the body sensor network to improve the QRS detection performance by dynamically selecting the leads with best SNR and taking advantage of the best features of two complementary detection algorithms. The accelerometer data from the BSN

Huaming Li; Jindong Tan

2006-01-01

120

Towards real time QRS detection: A fast method using minimal pre-processing  

Microsoft Academic Search

This paper proposes a method for the detection of QRS complexes. The method applies the algorithm proposed by Kupeev [K.Y. Kupeev, On significant maxima detection: a fine-to-coarse algorithm, in: Proceedings of the 13th International Conference on Pattern Recognition, IEEE, vol. 2, August 1996, pp. 270–274] to a shifting window over the ECG signal. The method was tested on the MIT-BIH

John Darrington

2006-01-01

121

QRS detection based ECG quality assessment.  

PubMed

Although immediate feedback concerning ECG signal quality during recording is useful, up to now not much literature describing quality measures is available. We have implemented and evaluated four ECG quality measures. Empty lead criterion (A), spike detection criterion (B) and lead crossing point criterion (C) were calculated from basic signal properties. Measure D quantified the robustness of QRS detection when applied to the signal. An advanced Matlab-based algorithm combining all four measures and a simplified algorithm for Android platforms, excluding measure D, were developed. Both algorithms were evaluated by taking part in the Computing in Cardiology Challenge 2011. Each measure's accuracy and computing time was evaluated separately. During the challenge, the advanced algorithm correctly classified 93.3% of the ECGs in the training-set and 91.6 % in the test-set. Scores for the simplified algorithm were 0.834 in event 2 and 0.873 in event 3. Computing time for measure D was almost five times higher than for other measures. Required accuracy levels depend on the application and are related to computing time. While our simplified algorithm may be accurate for real-time feedback during ECG self-recordings, QRS detection based measures can further increase the performance if sufficient computing power is available. PMID:22902864

Hayn, Dieter; Jammerbund, Bernhard; Schreier, Günter

2012-09-01

122

A real-time QRS detection and delineation algorithm based on the inflection angle of the ECG waveform  

Microsoft Academic Search

A fast and accurate algorithm is developed for the detection and delineation of QRS complexes. This algorithm uses an efficient data compression scheme to reduce the number of processing points. Easy implementation, accurate delineation, fast execution speed, baseline ignored, and no adaptive threshold values are the advantages of using the inflection angle. The average time to detect and delineate one

H.-S. H. Hsiung; C.-K. Cheng; G.-J. Jan

1989-01-01

123

Fusing conventional ECG QRS detection algorithms with an auto-associative neural network for the detection of ectopic beats  

Microsoft Academic Search

The onset of a potentially fatal arrhythmia is often preceded by abnormal morphologies in the QRS complex, the main feature in the electrocardiogram. However, these ectopic beats are difficult to detect as their shape is very similar to those found in a normal sinus rhythm. We show how an auto-associative multi-layer perceptron can be trained to detect normal beats only,

G. Clifford; L. Tarassenko; N. Townsend

2000-01-01

124

Quantitative analysis of the high-frequency components of the terminal portion of the body surface QRS in normal subjects and in patients with ventricular tachycardia.  

PubMed

Quantitative analysis of the high-frequency components of the terminal portion of the surface QRS was performed in 42 normal subjects (group 1, ages 18-67 years, mean +/- SEM 34.7 +/- 2.2 years) and in 12 patients with symptomatic, sustained ventricular tachycardia (VT) (group 2, ages 48-76 years, mean 59 +/- 2.3 years). Signal averaging and high-pass, bidirectional digital filtering were used for analysis. The total duration of the QRS, the duration of the low-amplitude signals (less than 40 microV) in the terminal portion of the QRS and the amplitude of the signals in the last 40 and 50 msec of the QRS were measured at filter settings of 25 and 40 Hz. Reproducibility of the measurements was tested in 15 normal subjects by comparing results obtained from two consecutive recordings. Significant differences were found between normal subjects and VT patients for all four indexes at both 25- and 40-Hz filters. Specific values for each of the indexes were identified at the 40-Hz filtering, which could separate normal subjects from VT patients (20 microV for the amplitude of last 40 msec; 30 microV for the amplitude of last 50 msec; 120 msec for the total duration; and 39 msec for the low-amplitude signal of the filtered QRS). Using these values for the four indexes, respectively, 90%, 98%, 100% and 90% of the normal subjects and 83%, 83%, 58% and 83% for the VT group were correctly classified. The results show that the high-frequency analysis of the signal-averaged body surface QRS is a reliable, reproducible, noninvasive method for distinguishing patients with VT from normal subjects. PMID:6831674

Denes, P; Santarelli, P; Hauser, R G; Uretz, E F

1983-05-01

125

Fetal QRS extraction from abdominal recordings via model-based signal processing and intelligent signal merging.  

PubMed

Noninvasive fetal ECG (fECG) monitoring has potential applications in diagnosing congenital heart diseases in a timely manner and assisting clinicians to make more appropriate decisions during labor. However, despite advances in signal processing and machine learning techniques, the analysis of fECG signals has still remained in its preliminary stages. In this work, we describe an algorithm to automatically locate QRS complexes in noninvasive fECG signals obtained from a set of four electrodes placed on the mother's abdomen. The algorithm is based on an iterative decomposition of the maternal and fetal subspaces and filtering of the maternal ECG (mECG) components from the fECG recordings. Once the maternal components are removed, a novel merging technique is applied to merge the signals and detect the fetal QRS (fQRS) complexes. The algorithm was trained and tested on the fECG datasets provided by the PhysioNet/CinC challenge 2013. The final results indicate that the algorithm is able to detect fetal peaks for a variety of signals with different morphologies and strength levels encountered in clinical practice. PMID:25069479

Haghpanahi, Masoumeh; Borkholder, David A

2014-08-01

126

[Wide QRS tachycardia preceded by pacemaker spikes].  

PubMed

The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral. PMID:23768570

Romero, M; Aranda, A; Gómez, F J; Jurado, A

2014-04-01

127

Analysis of First-Derivative Based QRS Detection Algorithms  

Microsoft Academic Search

Accurate QRS detection is an important first step for the analysis of heart rate variability. Algorithms based on the differentiated ECG are computationally efficient and hence ideal for real-time analysis of large datasets. Here, we analyze traditional first-derivative based squaring function (Hamilton-Tompkins) and Hilbert transform-based methods for QRS detection and their modifications with improved detection thresholds. On a standard ECG

Natalia M. Arzeno; Zhi-De Deng; Chi-Sang Poon

2008-01-01

128

Software QRS detection in ambulatory monitoring — a review  

Microsoft Academic Search

The QRS detection algorithm is an essential part of any computer-based system for the analysis of ambulatory ECG recordings.\\u000a This review asserts that most one-channel QRS detectors described in the literature can be considered as having the same basic\\u000a structure. A discussion of some of the current detection schemes is presented with regard to this structure. Some additional\\u000a features of

O. Pahlm; L. Sörnmo

1984-01-01

129

Body Sensor Network Based Context-Aware QRS Detection  

Microsoft Academic Search

In this paper, a body sensor network (BSN) based context-aware QRS detection scheme is proposed. The algorithm uses the context\\u000a information provided by the body sensor network to improve the QRS detection performance by dynamically selecting those leads\\u000a with the best SNR and taking advantage of the best features of two complementary detection algorithms. The accelerometer data\\u000a from the BSN

Hongxing Wei; Huaming Li; Jindong Tan

130

Month-to-month and year-to-year reproducibility of high frequency QRS ECG signals  

NASA Technical Reports Server (NTRS)

High frequency electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized. Therefore, we prospectively investigated the reproducibility of the root mean squared voltage, kurtosis, and the presence versus absence of reduced amplitude zones in signal averaged 12-lead high frequency QRS recordings acquired in the supine position one month apart in 16 subjects and one year apart in 27 subjects. Reproducibility of root mean squared voltage and kurtosis was excellent over these time intervals in the limb leads, and acceptable in the precordial leads using both the V-lead and CR-lead derivations. The relative error of root mean squared voltage was 12% month-to-month and 16% year-to-year in the serial recordings when averaged over all 12 leads. Reduced amplitude zones were also reproducible up to a rate of 87% and 81%, respectively, for the month-to-month and year-to-year recordings. We conclude that 12-lead high frequency QRS electrocardiograms are sufficiently reproducible for clinical use.

Batdorf, Niles J.; Feiveson, Alan H.; Schlegel, Todd T.

2004-01-01

131

Month-to-Month and Year-to-Year Reproducibility of High Frequency QRS ECG signals  

NASA Technical Reports Server (NTRS)

High frequency (HF) electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized. We therefore prospectively investigated the reproducibility of the root mean squared (RMS) voltage, kurtosis, and the presence versus absence of reduced amplitude zones (RAzs) in signal averaged 12-lead HF QRS recordings acquired in the supine position one month apart in 16 subjects and one year apart in 27 subjects. Reproducibility of RMS voltage and kurtosis was excellent over these time intervals in the limb leads, and acceptable in the precordial leads using both the V-lead and CR-lead derivations. The relative error of RMS voltage was 12% month-to-month and 16% year-to-year in the serial recordings when averaged over all 12 leads. RAzs were also reproducible at a rate of up to 87% and 8 1 %, respectively, for the month-to-month and year-to-year recordings. We conclude that 12-lead HF QRS electrocardiograms are sufficiently reproducible for clinical use.

Batdorf, Niles; Feiveson, Alan H.; Schlegel, Todd T.

2006-01-01

132

QRS slopes for assessment of myocardial damage in chronic chagasic patients  

NASA Astrophysics Data System (ADS)

In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease.

Pueyo, E.; Laciar, E.; Anzuola, E.; Laguna, P.; Jané, R.

2007-11-01

133

Chromosome passenger complexes control anaphase duration and spindle elongation via a kinesin-5 brake  

PubMed Central

During mitosis, chromosome passenger complexes (CPCs) exhibit a well-conserved association with the anaphase spindle and have been implicated in spindle stability. However, their precise effect on the spindle is not clear. In this paper, we show, in budding yeast, that a CPC consisting of CBF3, Bir1, and Sli15, but not Ipl1, is required for normal spindle elongation. CPC mutants slow spindle elongation through the action of the bipolar kinesins Cin8 and Kip1. The same CPC mutants that slow spindle elongation also result in the enrichment of Cin8 and Kip1 at the spindle midzone. Together, these findings argue that CPCs function to organize the spindle midzone and potentially switch motors between force generators and molecular brakes. We also find that slowing spindle elongation delays the mitotic exit network (MEN)–dependent release of Cdc14, thus delaying spindle breakdown until a minimal spindle size is reached. We propose that these CPC- and MEN-dependent mechanisms are important for coordinating chromosome segregation with spindle breakdown and mitotic exit.

Rozelle, Daniel K.; Hansen, Scott D.

2011-01-01

134

Chromosome passenger complexes control anaphase duration and spindle elongation via a kinesin-5 brake.  

PubMed

During mitosis, chromosome passenger complexes (CPCs) exhibit a well-conserved association with the anaphase spindle and have been implicated in spindle stability. However, their precise effect on the spindle is not clear. In this paper, we show, in budding yeast, that a CPC consisting of CBF3, Bir1, and Sli15, but not Ipl1, is required for normal spindle elongation. CPC mutants slow spindle elongation through the action of the bipolar kinesins Cin8 and Kip1. The same CPC mutants that slow spindle elongation also result in the enrichment of Cin8 and Kip1 at the spindle midzone. Together, these findings argue that CPCs function to organize the spindle midzone and potentially switch motors between force generators and molecular brakes. We also find that slowing spindle elongation delays the mitotic exit network (MEN)-dependent release of Cdc14, thus delaying spindle breakdown until a minimal spindle size is reached. We propose that these CPC- and MEN-dependent mechanisms are important for coordinating chromosome segregation with spindle breakdown and mitotic exit. PMID:21482719

Rozelle, Daniel K; Hansen, Scott D; Kaplan, Kenneth B

2011-04-18

135

Low Power Adder Based Digital Filter for QRS Detector  

PubMed Central

Most of the Biomedical applications use dedicated processors for the implementation of complex signal processing. Among them, sensor network is also a type, which has the constraint of low power consumption. Since the processing elements are the most copiously used operations in the signal processors, the power consumption of this has the major impact on the system level application. In this paper, we introduce low power concept of transistor stacking to reduce leakage power; and new architectures based on stacking to implement the full adder and its significance at the digital filter level for QRS detector are implemented. The proposed concept has lesser leakage power at the adder as well as filter level with trade-off in other quality metrics of the design. This enabled the design to be dealt with as the low-power corner and can be made adaptable to any level of hierarchical abstractions as per the requirement of the application. The proposed architectures are designed, modeled at RTL level using the Verilog-HDL, and synthesized in Synopsys Design Compiler by mapping the design to 65?nm technology library standard cells.

Murali, L.; Chitra, D.; Manigandan, T.

2014-01-01

136

Aviation System Analysis Capability (ASAC) Quick Response System (QRS) Test Report  

NASA Technical Reports Server (NTRS)

This document is the Aviation System Analysis Capability (ASAC) Quick Response System (QRS) Test Report. The purpose of this document is to present the results of the QRS unit and system tests in support of the ASAC QRS development effort. This document contains an overview of the project background and scope, defines the QRS system and presents the additions made to the QRS this year, explains the assumptions, constraints, and approach used to conduct QRS Unit and System Testing, and presents the schedule used to perform QRS Testing. The document also presents an overview of the Logistics Management Institute (LMI) Test Facility and testing environment and summarizes the QRS Unit and System Test effort and results.

Roberts, Eileen; Villani, James A.; Ritter, Paul

1997-01-01

137

Separated right and left ventricular excitation during right ventricular septal pacing in a patient with narrow QRS wave: a case report  

PubMed Central

Introduction Right ventricular septal pacing is thought to be better than right ventricular apical pacing for shortening the QRS duration and for preserving left ventricular function. However, right ventricular septal pacing may not be effective in all cases. In this case report, we present a rare case in which right ventricular septal pacing induced thoroughly separated right and left ventricular excitation despite the presence of a relatively narrow QRS wave during atrium-only pacing. Case presentation We report a case of 63-year-old Japanese man with cardiomyopathy with an implantable cardioverter defibrillator placement for ventricular tachycardia. Three years after implantation, he developed second-degree atrio-ventricular block. Therefore, atrio-ventricular sequential pacing was started; then his heart failure was much worsened. His electrocardiogram showed a dissociated biphasic QRS wave during right ventricular high-septal pacing, despite the presence of a non-fragmented QRS morphology during atrium-only pacing. An activation map during right ventricular high-septal pacing showed that right ventricular conduction started at the pacing site and ended at the right ventricular basal inferior site. Subsequently after a 10ms interval, left ventricular conduction started at the left ventricular posteroseptum and ended at the left ventricular lateral wall. These data indicate that during right ventricular high-septal pacing, the first component of the QRS wave supposedly reflects only right ventricular excitation and the second component only left ventricular excitation. Also due to the intracardiac electrograms, it was assumed that this phenomenon was caused by transversely limited severe transseptal conduction disturbance. Conclusion It should be noted that even ventricular septal pacing could evoke harmful interventricular dyssynchrony due to transversely limited severe septal conduction disturbance, despite the presence of a relatively narrow QRS wave.

2014-01-01

138

Complex Biventricular Pacing - A Case Series  

PubMed Central

It is established that cardiac resynchronisation therapy (CRT) reduces mortality and hospitalisation and improves functional class in patients with NYHA class 3-4 heart failure, an ejection fraction of ? 35% and a QRS duration of ? 120ms. Recent updates in the American guidelines have expanded the demographic of patients in whom CRT may be appropriate. Here we present two cases of complex CRT; one with a conventional indication but occluded central veins and the second with a novel indication for CRT post cardiac transplant.

Hodkinson, Emily Catherine; Morrice, Keith; Loan, William; Nicholas, Jacob; Chew, EngWooi

2014-01-01

139

Evaluation of real-time QRS detection algorithms in variable contexts  

Microsoft Academic Search

A method is presented to evaluate the detection performance of real-time QRS detection algorithms to propose a strategy for\\u000a the adaptive selection of QRS detectors, in variable signal contexts. Signal contexts are defined as different combinations\\u000a of QRS morphologies and clinical noise. Four QRS detectors are compared in these contexts by means of a multivariate analysis.\\u000a This evaluation strategy is

François Portet; Alfredo I. Hernández; Guy Carrault

2005-01-01

140

Age and sex dependent criteria for lower limits of QRS voltages  

Microsoft Academic Search

The aim of this study was to examine whether criteria for low QRS voltage should be age and sex dependent. A database of 1496 normal ECGs from healthy adults was analysed using the University of Glasgow ECG analysis program. Correlation coefficients between peak- to-peak QRS voltages (ppQRS) and age were obtained. Differences in ppQRS due to sex were measured statistically.

E. Clark; B. Devine; P. W. Macfarlane

2006-01-01

141

QRS detection for pacemakers in a noisy environment using a time lagged artificial neural network  

Microsoft Academic Search

ABSTRACT A time lagged feedforward,artificial neural network,(TLFN) is used,to detect QRS complexes,for pacemakers,in a noisy environment.,The,TLFN reduces,the,influence,of,lower frequencies in the invasive electrogram (EG) signals, such as the P and T waves. The TLFN output is then subjected to matched filtering with a dynamically,updated impulse,response. Detector performance($#$#$#Commof databases,containing electrograms,and noise such that different types of noise and interferences,from,electronic,appliances,are added,to the electrograms.

Joachim Neves Rodrigues; Viktor Öwall; Leif Sörnmo

2001-01-01

142

A new QRS detection algorithm based on the Hilbert transform  

Microsoft Academic Search

A robust new algorithm for QRS defection using the properties of the Hilbert transform is proposed. The method allows R waves to be differentiated from large, peaked T and P waves with a high degree of accuracy and minimizes the problems associated with baseline drift, motion artifacts and muscular noise. The performance of the algorithm was tested using the records

D. S. Benitez; P. A. Gaydecki; A. Zaidi; A. P. Fitzpatrick

2000-01-01

143

A QRS detection algorithm based on Haar wavelet  

Microsoft Academic Search

An on-line QRS detection algorithm was developed. It is based on the Haar wavelet and implemented as a recursive filter. Because it works with fixed-point arithmetic and it avoids overflow error, there is no cumulative error. The performance of the detector was evaluated: 1) On a set of clinical records. 2) On a normal segment of lead II. Here, it

A. Gutierrez; PR Hernandez; M. Lara; SJ Perez

1998-01-01

144

Real time electrocardiogram QRS detection using combined adaptive threshold  

Microsoft Academic Search

BACKGROUND: QRS and ventricular beat detection is a basic procedure for electrocardiogram (ECG) processing and analysis. Large variety of methods have been proposed and used, featuring high percentages of correct detection. Nevertheless, the problem remains open especially with respect to higher detection accuracy in noisy ECGs METHODS: A real-time detection method is proposed, based on comparison between absolute values of

Ivaylo I Christov

2004-01-01

145

Novel QRS Detection by CWT for ECG Sensor  

Microsoft Academic Search

Existing wavelet transform methods usually realize the QRS detection by sourcing for two modulus maxima with opposite sign and locating the zero crossing point between them at high decomposition scale. However high scale wavelet transform is often contaminated with severe baseline drift. In addition, common sense indicates that detecting zero crossing is not an easy task compared to the detection

Fei Zhang; Yong Lian

2007-01-01

146

Louisiana Quality Start Child Care Rating System: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Louisiana's Quality Start Child Care Rating System prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs;…

Child Trends, 2010

2010-01-01

147

Los Angeles County Steps to Excellence Project: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Los Angeles County's Steps to Excellence Project prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs;…

Child Trends, 2010

2010-01-01

148

New Mexico Look for the STARS--AIM HIGH: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of New Mexico's Look for the STARS--AIM HIGH prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4)…

Child Trends, 2010

2010-01-01

149

Tennessee Star-Quality Child Care Program: QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of Tennessee's Star-Quality Child Care Program prepared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for Center-Based Programs; (4)…

Child Trends, 2010

2010-01-01

150

Complex Valued Wavelet Analysis for QRS Detection in ECG signals  

Microsoft Academic Search

During the last fifteen years, the wavelet transform has proven to be a valuable tool in many application areas for analysis of nonstationary signals such as the biomedical signals, and the ECG signal in particular. The wavelet transform provides a time-frequency representation of the signal, and thus permits the inspection of characteristic waves of the ECG signal at different scales

Vladimir Johneff

151

Electrocardiogram QRS Detection Using Multiscale Filtering Based on Mathematical Morphology  

Microsoft Academic Search

A novel QRS detection algorithm based on multi-scale mathematical morphology (3M) and multi-frame differential modulus cumulation is proposed in this paper. The algorithm introduces the multi-stage filtering based on mathematical morphology from image processing field into ECG analysis to suppress the impulsive noise, and adopts multi-frame differential modulus cumulation to remove the baseline drift and enhance the signal. An average

Fei Zhang; Yong Lian

2007-01-01

152

Interglacial Durations  

NASA Astrophysics Data System (ADS)

In the context of future global warming induced by human activities, it is essential to assess the role of natural climatic variations. Precise knowledge of the duration of past interglacial periods is fundamental to the understanding of the potential future evolution of the Holocene. Past ice age cycles provide a natural laboratory for exploring the progression and duration of interglacial climate. Palaeorecords from ice, land and oceans extend over the last 800 ka, revealing eight glacial-interglacial cycles, with a range of insolation and greenhouse gas influences. The interglacials display a correspondingly large variety of intensity and duration, thus providing an opportunity for major insights into the mechanisms involved in the behaviour of interglacial climates. A comparison of the duration of these interglacials, however, is often difficult, as the definition of an interglacial depends on the archive that is considered. Therefore, to compare interglacial length and climate conditions from different archives, a consistent definition of interglacial conditions is required, ideally one that is not bound to the method nor to the archive under consideration. Here we present a method to identify interglacials and to calculate their length by mean of a simple statistical approach. We based our method on ~ 400 ka windows of time to determine mean climatic conditions while allowing for the possibility of long term evolution of the climatic baseline. For our study of interglacials of the past 800 ka, we used two windows that largely align with the pre- (800-430 ka ago) and post- (430-0 ka ago) mid-Brunhes event (MBE), although the resulting conclusions are not sensitive to this particular division. We applied this method to the last 800 ka of a few palaeoclimate records: the deuterium ice core (EDC) record as a climatic proxy, the benthic ?18O stack (LR04) as a proxy for sea level/ice volume, ice core (Vostok, EDC) atmospheric CO2 and additional records. Although each climatic parameter has its own interglacial duration in this approach, important overall patterns emerge for individual interglacials. Interglacial conditions during the last interglacial, marine isotope stage (MIS) 5, as well as most pre-MBE interglacials persisted somewhat longer than the elapsed duration of the Holocene, while MIS 7 was shorter, and MIS 9 and MIS 19 were similar in duration. The longest interglacial durations overall characterized MIS 11, a frequent candidate as a potential Holocene and near future analogue because of similar orbital configurations (similarity shared also with MIS 19). Our study also reveals that interglacial high CO2 levels on the whole are within the duration range of the other paleoclimatic proxies and similar in length with the deuterium EDC record. This suggests that CO2 essentially plays a role of feedback when contributing to interglacial's duration. This exercise highlights the stability and variability in duration of the different interglacials as recorded in various proxy records under natural climate conditions. It may help identify past interglacial periods with conditions similar to those observed in the Holocene thus far, thereby allowing improved understanding of the human impact on climate.

Mangili, Clara; McManus, Jerry F.; Raynaud, Dominique

2014-05-01

153

Real-Time, High-Frequency QRS Electrocardiograph  

NASA Technical Reports Server (NTRS)

An electronic system that performs real-time analysis of the low-amplitude, high-frequency, ordinarily invisible components of the QRS portion of an electrocardiographic signal in real time has been developed. Whereas the signals readily visible on a conventional electrocardiogram (ECG) have amplitudes of the order of a millivolt and are characterized by frequencies <100 Hz, the ordinarily invisible components have amplitudes in the microvolt range and are characterized by frequencies from about 150 to about 250 Hz. Deviations of these high-frequency components from a normal pattern can be indicative of myocardial ischemia or myocardial infarction

Schlegel, Todd T.; DePalma, Jude L.; Moradi, Saeed

2003-01-01

154

Performance of Three QRS Detection Algorithms During Sleep: A comparative Study.  

National Technical Information Service (NTIS)

A comparison of the performance of three QRS detectors used in the analysis of electrocardiogram (ECG) during sleep in presented in this paper. Two widely used QRS detection algorithms based on digital filtering (DF) are compared with a newly introduced o...

L. J. Hadjileontiadis K. I. Panoulas T. Penzel S. M. Panas

2001-01-01

155

A robust method for QRS detection based on modified p-spectrum  

Microsoft Academic Search

In this paper, we propose a robust method based on the mod- iřed p-spectrum to detect heart beats in ECG signals, which is also referred as QRS detection in the literature. QRS de- tection is an old problem that has been studied for several decades. In the literature, there are many methods based on various forms of transformations and thresholding,

Peng Qiu; K. J. Ray Liu

2008-01-01

156

An Effective QRS Detection Algorithm for Wearable ECG in Body Area Network  

Microsoft Academic Search

A novel QRS detection algorithm for wearable ECG devices and its FPGA implementation are presented in this paper. The proposed algorithm utilizes the hybrid opening- closing mathematical morphology filtering to suppress the impulsive noise and remove the baseline drift and uses modulus accumulation to enhance the signal. The proposed algorithm achieves an average QRS detection rate of 99.53%, a sensitivity

Fei Zhang; Jun Tan; Yong Lian

2007-01-01

157

A real-time microprocessor QRS detector system with a 1-ms timing accuracy for the measurement of ambulatory HRV  

Microsoft Academic Search

The design, test methods, and results of an ambulatory QRS detector are presented. The device is intended for the accurate measurement of heart rate variability (HRV) and reliable QRS detection in both ambulatory and clinical use. The aim of the design work was to achieve high QRS detection performance in terms of timing accuracy and reliability, without compromising the size

Antti Ruha; Sami Sallinen; S. Nissila

1997-01-01

158

Risk of Mortality in Individuals With Low QRS Voltage and Free of Cardiovascular Disease.  

PubMed

The prognostic significance of low QRS voltage (LQRSV) in the electrocardiogram (ECG) of individuals free of cardiovascular disease (CVD) is unclear. We evaluated the association between LQRSV and all-cause mortality in 6,440 participants (53% women, mean age 60 years) from the Third National Health and Nutrition Examination Survey, a representative sample of the US population. Participants with history of CVD or major ECG abnormalities were excluded. LQRSV was automatically defined from standard 12-lead ECG as QRS complex amplitudes of <0.5 mV in all frontal leads and/or <1.0 mV in all precordial leads. Mortality data through 2006 were obtained from National Death Index records. LQRSV was detected in 1.4% (n = 89) of the participants. During a median follow-up of 13.8 years, 2,000 deaths occurred. The mortality rate in individuals with LQRSV was almost twice that in those without LQRSV (51.1 vs 23.5 events per 1,000 person-years, p <0.01). In a demographic-adjusted model, LQRSV was associated with 63% increased risk of mortality (hazard ratio 1.63, 95% confidence interval [1.21, 2.18]). The magnitude of this risk did not appreciably change after additional adjustment for body mass index, smoking status, systolic blood pressure, blood pressure medication use, dyslipidemia, diabetes, cancer, pulmonary disease, and ECG abnormalities (hazard ratio 1.61, 95% confidence interval [1.20, 2.16]) and was consistent across age, race, and sex subcategories. In conclusion, LQRSV is associated with an increased risk of mortality in individuals free of apparent CVD. More research is warranted to determine the mechanisms by which LQRSV is associated with increased risk of mortality in apparently healthy individuals. PMID:24630386

Usoro, Andrew O; Bradford, Natalie; Shah, Amit J; Soliman, Elsayed Z

2014-05-01

159

Relation of QRS Shortening to Cardiac Output During Temporary Resynchronization Therapy after Cardiac Surgery  

PubMed Central

Cardiac resynchronization therapy (CRT) can improve cardiac function in heart failure without increasing myocardial oxygen consumption. However, CRT optimization based on hemodynamics or echocardiography is difficult. QRS duration (QRSd) is a possible alternative optimization parameter. Accordingly, we assessed QRSd optimization of CRT during cardiac surgery. We hypothesized that QRSd shortening during changes in interventricular pacing delay (VVD) would increase cardiac output (CO). Seven patients undergoing coronary artery bypass, aortic or mitral valve surgery with LV ejection fraction ? 40% and QRSd ? 100 msec were studied. CRT was implemented at epicardial pacing sites in the left and right ventricle and right atrium during VVD variation after cardiopulmonary bypass. QRSd was correlated with CO from an electromagnetic aortic flow probe. Both positive and negative correlations were observed. Correlation coefficients ranged from 0.70 to ?0.74 during VVD testing. Clear minima in QRSd were observed in four patients and were within 40 msec of maximum CO in two. We conclude that QRSd is not useful for routine optimization of VVD after cardiac surgery but may be useful in selected patients. Decreasing QRSd is associated with decreasing CO in some patients, suggesting that CRT can affect determinants of QRSd and ventricular function independently.

Spotnitz, Matthew E.; Richmond, Marc E.; Quinn, T. Alexander; Cabreriza, Santos E.; Wang, Daniel Y.; Albright, Catherine M.; Weinberg, Alan D.; Dizon, Jose M.; Spotnitz, Henry M.

2011-01-01

160

Determinants of arrhythmogenic ventricular activity detected on the body surface QRS in patients with coronary artery disease.  

PubMed

The prevalence of arrhythmogenic ventricular activity (AVA) was investigated in 166 patients with coronary artery disease. Thirty patients had documented ventricular tachycardia (VT)/ventricular fibrillation (VF). Bipolar X, Y, Z leads were signal-averaged and filtered with a 40-Hz, bidirectional, high-pass digital filter. The filtered QRS signals were analyzed for the amplitude of the last 40 and 50 ms; duration of low-amplitude potentials (less than 40 microV) in the terminal portion; and duration of the filtered QRS. A positive AVA test result was defined as the presence of 2 or more abnormal indexes. Of the 30 patients with VT/VF, 66% had positive AVA test results (AVA-positive patients). Of the 136 patients without VT/VF, 25% had positive AVA test results. The following univariate variables showed significant correlation with an AVA-positive test: age, previous myocardial infarction, previous VT/VF, left ventricular wall motion abnormalities and left ventricular ejection fraction. Multivariate stepwise discriminant function analysis revealed that the presence of previous myocardial infarction and history of sustained VT/VF were the only independent determinants of AVA. During electrophysiologic studies, sustained VT/VF could be induced in 77% of the AVA-positive patients (24 of 31) and in 30% of the AVA-negative patients (3 of 10). The survival probabilities for 6, 12 and 18 months of follow-up were 92%, 85% and 85% for the AVA-positive and 97%, 92% and 90% for the AVA-negative patients. Our findings support the concept that a positive AVA test result reflects areas of delayed ventricular activation. The areas of delayed ventricular activation are associated with previous myocardial injury and scar tissue and serve as an anatomic basis for reentry.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6731295

Denes, P; Uretz, E; Santarelli, P

1984-06-01

161

Development of a Multi-Channel, High Frequency QRS Electrocardiograph  

NASA Technical Reports Server (NTRS)

With the advent of the ISS era and the potential requirement for increased cardiovascular monitoring of crewmembers during extended EVAs, NASA flight surgeons would stand to benefit from an evolving technology that allows for a more rapid diagnosis of myocardial ischemia compared to standard electrocardiography. Similarly, during the astronaut selection process, NASA flight surgeons and other physicians would also stand to benefit from a completely noninvasive technology that, either at rest or during maximal exercise tests, is more sensitive than standard ECG in identifying the presence of ischemia. Perhaps most importantly, practicing cardiologists and emergency medicine physicians could greatly benefit from such a device as it could augment (or even replace) standard electrocardiography in settings where the rapid diagnosis of myocardial ischemia (or the lack thereof) is required for proper clinical decision-making. A multi-channel, high-frequency QRS electrocardiograph is currently under development in the Life Sciences Research Laboratories at JSC. Specifically the project consisted of writing software code, some of which contained specially-designed digital filters, which will be incorporated into an existing commercial software program that is already designed to collect, plot and analyze conventional 12-lead ECG signals on a desktop, portable or palm PC. The software will derive the high-frequency QRS signals, which will be analyzed (in numerous ways) and plotted alongside of the conventional ECG signals, giving the PC-viewing clinician advanced diagnostic information that has never been available previously in all 12 ECG leads simultaneously. After the hardware and software for the advanced digital ECG monitor have been fully integrated, plans are to use the monitor to begin clinical studies both on healthy subjects and on patients with known coronary artery disease in both the outpatient and hospital settings. The ultimate goal is to get the technology out into the clinical world, where it has the potential to save lives.

DePalma, Jude L.

2003-01-01

162

A real-time QRS detection method based on moving-averaging incorporating with wavelet denoising  

Microsoft Academic Search

In this paper, a simple moving average-based computing method for real-time QRS detection is proposed. In addition, for signal preprocessing our detection algorithm also incorporates a wavelet-based denoising procedure to effectively reduce the noise level for electrocardiogram (ECG) data. The overall computational structure of the proposed algorithm allows the QRS detection to be performed and implemented in real-time with high

Szi-wen Chen; Hsiao-chen Chen; Hsiao-lung Chan

2006-01-01

163

Cardiac magnetic resonance imaging in arrhythmogenic right ventricular cardiomyopathy: correlation to the QRS dispersion.  

PubMed

The aim of the study was to evaluate the relationship between the presence of right ventricular abnormalities detected by cardiac magnetic resonance (CMR) and QRS dispersion, the strongest independent predictor of sudden death in ARVC. A consecutive series of 40 patients from a single institution were recruited with a clinical diagnosis of ARVC based on the diagnostic criteria. All patients underwent systematic clinical evaluation, including history and examination, electrocardiography, 24-h Holter monitor, chest radiography, echocardiography and CMR examination and were divided into two groups according to the QRS dispersion: group I, QRS dispersion ?40 ms; group II, QRS dispersion <40 ms. The relationship between the characteristic parameters of CMR image and QRS dispersion were analyzed in two groups. There were significant differences in QRS dispersion (57±14 ms vs. 26±11 ms), right ventricular end-diastolic diameter (57±10 mm vs. 48±11 mm, P=.012), right ventricular end-systolic diameter (52±10 mm vs. 44±11 mm, P=.010), right ventricular end-diastolic volume (260±105 ml vs. 180±66 ml, P=.006), right ventricular end-systolic volume (222±98 ml vs. 148±61 ml, P=.006) and myocardial fibrosis detection rate (74% vs. 38%, P=.024) between two groups. For all patients with ARVC, QRS dispersion and right ventricular end-diastolic volume (r=0.66, P<.001), right ventricular end-systolic volume (r=0.67, P<.001), right ventricular outflow tract area (r=0.68, P<.001) showed a moderate positive correlation. Right ventricular outflow tract area, right ventricular end-diastolic volume and end-systolic volume detected by CMR in patients with ARVC were positively correlated to the extent of QRS dispersion (?40 ms), the strongest independent predictor of sudden cardiac death. PMID:22819580

Ma, Ning; Cheng, Huaibing; Lu, Minjie; Jiang, Shiliang; Yin, Gang; Zhao, Shihua

2012-12-01

164

A 0.83- ?W QRS detection processor using quadratic spline wavelet transform for wireless ECG acquisition in 0.35- ?m CMOS.  

PubMed

Healthcare electronics count on the effectiveness of the on-patient signal preprocessing unit to moderate the wireless data transfer for better power efficiency. In order to reduce the system power in long-time ECG acquisition, this work describes an on-patient QRS detection processor for arrhythmia monitoring. It extracts the concerned ECG part, i.e., the RR-interval between the QRS complex for evaluating the heart rate variability. The processor is structured by a scale-3 quadratic spline wavelet transform followed by a maxima modulus recognition stage. The former is implemented via a symmetric FIR filter, whereas the latter includes a number of feature extraction steps: zero-crossing detection, peak (zero-derivative) detection, threshold adjustment and two finite state machines for executing the decision rules. Fabricated in 0.35-?m CMOS the 300-Hz processor draws only 0.83 ?W, which is favorably comparable with the prior arts. In the system tests, the input data is placed via an on-chip 10-bit SAR analog-to-digital converter, while the output data is emitted via an off-the-shelf wireless transmitter (TI CC2500) that is configurable by the processor for different data transmission modes: 1) QRS detection result, 2) raw ECG data or 3) both. Validated with all recordings from the MIT-BIH arrhythmia database, 99.31% sensitivity and 99.70% predictivity are achieved. Mode 1 with solely the result of QRS detection exhibits 6× reduction of system power over modes 2 and 3. PMID:23853259

Ieong, Chio-In; Mak, Pui-In; Lam, Chi-Pang; Dong, Cheng; Vai, Mang-I; Mak, Peng-Un; Pun, Sio-Hang; Wan, Feng; Martins, Rui P

2012-12-01

165

Spatial, individual, and temporal variation of the high-frequency QRS amplitudes in the 12 standard electrocardiographic leads  

Microsoft Academic Search

Background Analysis of high-frequency QRS amplitudes (HF-QRS) may provide an additional diagnostic tool in patients with heart disease, but the basic properties of these waveforms have not been sufficiently investigated. This study describes the spatial, individual, and temporal variation at rest of HF-QRS recorded with the 12 standard electrocardiographic leads in patients with ischemic heart disease.Methods and Results Two consecutive

Jonas Pettersson; Elena Carro; Lars Edenbrandt; Charles Maynard; Olle Pahlm; Michael Ringborn; Leif Sörnmo; Stafford G Warren; Galen S Wagner

2000-01-01

166

Etanercept Induces Low QRS Voltage and Autonomic Dysfunction in Mice with Experimental Chagas Disease  

PubMed Central

Background Chagas disease is a tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. Chagasic cardiomyopathy is characterized by disorders of autonomic regulation and action potential conduction in the acute and chronic phases of infection. Although tumor necrosis factor alpha (TNF-?) has been linked to cardiomyopathy in experimental models and in patients with Chagas disease, other reports suggest that TNF-? may exert anti-parasitic actions during the acute phase of infection. Objectives This study aimed to determine the effects of a soluble TNF-? blocker, etanercept, on electrocardiographic parameters in the acute phase of experimental infection with Trypanosoma cruzi. Methods Electrocardiograms were obtained from untreated infected mice and infected mice who were treated with etanercept 7 days after infection. ECG wave and heart rate variability parameters were determined using Chart for Windows. Results Etanercept treatment resulted in a low QRS voltage and decreased heart rate variability compared with no treatment. However, the treated mice exhibited a delay in the fall of the survival curve during the acute phase. Conclusion The results of this study suggest that although etanercept treatment promotes survival in mice infected with a virulent T. cruzi strain, TNF-? blockade generates a low voltage complex and autonomic dysfunction during the acute phase of infection. These findings indicate that mortality during the acute phase can be attributed to a systemic inflammatory response rather than cardiac dysfunction.

Rodriguez-Angulo, Hector; Garcia, Oscar; Castillo, Endher; Cardenas, Edward; Marques, Juan; Mijares, Alfredo

2013-01-01

167

Influence of crude protein content, ingredient complexity, feed form, and duration of feeding of the Phase I diets on productive performance and nutrient digestibility of Iberian pigs.  

PubMed

The influence of CP content and ingredient complexity, feed form, and duration of feeding of the Phase I diets on growth performance and total tract apparent digestibility (TTAD) of energy and nutrients was studied in Iberian pigs weaned at 28 d of age. There were 12 dietary treatments with 2 type of feeds (high-quality, HQ; and low-quality, LQ), 2 feed forms (pellets vs. mash), and 3 durations (7, 14, and 21 d) of supply of the Phase I diets. From d 7, 14, or 21 (depending on treatment) to d 35, all pigs received a common diet in mash form. Each treatment was replicated 3 times (6 pigs/pen). For the entire experiment, ADG (P < 0.05) and ADFI (P < 0.01) were less with the HQ than the LQ Phase I diets, but G:F was not affected. Pelleting of the Phase I diets did not affect ADG but improved G:F (P < 0.01). Feeding the Phase I diets from d 0 to 21 improved G:F (P < 0.05) but decreased ADG (P < 0.01) as compared with 7 or 14 d of feeding. Postweaning diarrhea (PWD) tended to be greater (P = 0.06) for pigs fed the HQ diets than pigs fed the LQ diets and pigs fed pellets than those fed mash (P < 0.001). Also, PWD was greater for pigs fed the Phase I diet for 14 or 21 d than those fed the diet for 7 d (P < 0.01). From d 0 to 21, ADG and G:F were not affected (P > 0.10) by feed quality, but feeding pellets or increasing the duration of feeding the Phase I diets improved G:F (P < 0.01). Also, in this period, PWD was greater with pellets than with mash and for pigs fed the Phase I diets for 14 or 21 d than for pigs fed the diet for only 7 d (P < 0.01). From d 21 to 35, pigs previously fed the LQ diet had greater ADG than pigs fed the HQ Phase I diets (P < 0.001). Also, pigs fed the Phase I diets for 21 d had decreased ADG (P < 0.05) and ADFI (P < 0.001) and reduced G:F (P < 0.05) than pigs fed these diets for 7 or 14 d. Organic matter digestibility was greater for pigs fed the HQ Phase I diets than pigs fed the LQ Phase I diets (P < 0.05). Pelleting improved TTAD of all nutrients (P < 0.01). It is concluded that HQ Phase I diets increased TTAD of nutrients but not feed efficiency of Iberian pigs from d 0 to 35. Also, pelleting improved energy and nutrient digestibility and feed efficiency. Increasing the duration of supply of the Phase I diets from 7 to 21 d improved feed efficiency but reduced ADG. Therefore, the use of LQ Phase I diets in pellet form for no more than 7 d after weaning is recommended in Iberian pigs. PMID:23307842

Berrocoso, J D; Saldańa, B; Serrano, M P; Cámara, L; Ibáńez, M A; Mateos, G G

2013-03-01

168

District of Columbia Going for the Gold Tiered Rate Reimbursement System. QRS Profile. The Child Care Quality Rating System (QRS) Assessment  

ERIC Educational Resources Information Center

This paper presents a profile of District of Columbia's Going for the Gold Tiered Rate Reimbursement Systemp repared as part of the Child Care Quality Rating System (QRS) Assessment Study. The profile consists of several sections and their corresponding descriptions including: (1) Program Information; (2) Rating Details; (3) Quality Indicators for…

Child Trends, 2010

2010-01-01

169

Development of an automated updated Selvester QRS scoring system using SWT-based QRS fractionation detection and classification.  

PubMed

The Selvester score is an effective means for estimating the extent of myocardial scar in a patient from low-cost ECG recordings. Automation of such a system is deemed to help implementing low-cost high-volume screening mechanisms of scar in the primary care. This paper describes, for the first time to the best of our knowledge, an automated implementation of the updated Selvester scoring system for that purpose, where fractionated QRS morphologies and patterns are identified and classified using a novel stationary wavelet transform (SWT)-based fractionation detection algorithm. This stage informs the two principal steps of the updated Selvester scoring scheme--the confounder classification and the point awarding rules. The complete system is validated on 51 ECG records of patients detected with ischemic heart disease. Validation has been carried out using manually detected confounder classes and computation of the actual score by expert cardiologists as the ground truth. Our results show that as a stand-alone system it is able to classify different confounders with 94.1% accuracy whereas it exhibits 94% accuracy in computing the actual score. When coupled with our previously proposed automated ECG delineation algorithm, that provides the input ECG parameters, the overall system shows 90% accuracy in confounder classification and 92% accuracy in computing the actual score and thereby showing comparable performance to the stand-alone system proposed here, with the added advantage of complete automated analysis without any human intervention. PMID:24403417

Bono, Valentina; Mazomenos, Evangelos B; Chen, Taihai; Rosengarten, James A; Acharyya, Amit; Maharatna, Koushik; Morgan, John M; Curzen, Nick

2014-01-01

170

Changes in High-Frequency QRS Components Are More Sensitive than ST-Segment Deviation for Detecting Acute Coronary Artery Occlusion  

Microsoft Academic Search

OBJECTIVES This study describes changes in high-frequency QRS components (HF-QRS) during percutaneous transluminal coronary angioplasty (PTCA) and compares the ability of these changes in HF-QRS and ST-segment deviation in the standard 12-lead electrocardiogram (ECG) to detect acute coronary artery occlusion. BACKGROUND Previous studies have shown decreased HF-QRS in the frequency range of 150 -250 Hz during acute myocardial ischemia. It

Jonas Pettersson; Olle Pahlm; Elena Carro; Lars Edenbrandt; Michael Ringborn; Leif Sornmo; Stafford G. Warren; Galen S. Wagner

2000-01-01

171

[ECG QRS signal detection and control system design of ventricular assist device].  

PubMed

In order to achieve auxiliary timing of ventricular assisting device to automatically track the ECG signals, we designed a set of ECG acquisition circuit in our study for the first time. Then we carried out ECG acquisition, smoothing filter and QRS detection on the LabVIEW. With the QRS signal as a benchmark, the control system immediately triggered ventricular assisting device to trigger the heart to contract for ejection for about 300 ms, and then to assist to make it relax. The practical effects of the experiment proved that ECG acquisition circuit had the feature of strong anti-interference, and control system had no false QRS detection and no false triggering of assist device. This achieves the auxiliary timing which could automatically track the ECG signal. PMID:23865330

Liao, Huogen; Yang, Ming; Zhuang, Xiaoqi; Huang, Huan

2013-06-01

172

Online digital filter and QRS detector applicable in low resource ECG monitoring systems.  

PubMed

The present work describes fast computation methods for real-time digital filtration and QRS detection, both applicable in autonomous personal ECG systems for long-term monitoring. Since such devices work under considerable artifacts of intensive body and electrode movements, the input filtering should provide high-quality ECG signals supporting the accurate ECG interpretation. In this respect, we propose a combined high-pass and power-line interference rejection filter, introducing the simple principle of averaging of samples with a predefined distance between them. In our implementation (sampling frequency of 250 Hz), we applied averaging over 17 samples distanced by 10 samples (Filter10x17), thus realizing a comb filter with a zero at 50 Hz and high-pass cut-off at 1.1 Hz. Filter10x17 affords very fast filtering procedure at the price of minimal computing resources. Another benefit concerns the small ECG distortions introduced by the filter, providing its powerful application in the preprocessing module of diagnostic systems analyzing the ECG morphology. Filter10x17 does not attenuate the QRS amplitude, or introduce significant ST-segment elevation/depression. The filter output produces a constant error, leading to uniform shifting of the entire P-QRS-T segment toward about 5% of the R-peak amplitude. Tests with standardized ECG signals proved that Filter10x17 is capable to remove very strong baseline wanderings, and to fully suppress 50 Hz interferences. By changing the number of the averaged samples and the distance between them, a filter design with different cut-off and zero frequency could be easily achieved. The real-time QRS detector is designed with simplified computations over single channel, low-resolution ECGs. It relies on simple evaluations of amplitudes and slopes, including history of their mean values estimated over the preceding beats, smart adjustable thresholds, as well as linear logical rules for identification of the R-peaks in real-time. The performance of the QRS detector was tested with internationally recognized ECG databases (AHA, MIT-BIH, European ST-T database), showing mean sensitivity of 99.65% and positive predictive value of 99.57%. The performance of the presented QRS detector can be highly rated, comparable and even better than other published real-time QRS detectors. Examples representing some typical unfavorable conditions in real ECGs, illustrate the common operation of Filter10x17 and the QRS detector. PMID:18752068

Tabakov, Serafim; Iliev, Ivo; Krasteva, Vessela

2008-11-01

173

Duration discretisation for activity recognition.  

PubMed

Activity recognition has become a key component within smart environments that aim at providing assistive solutions for their users. Learning high level activities from low level sensor data depends on several parameters, one of which is the duration of the activities themselves. Nevertheless, directly incorporating continuous duration values into a model is a complex process and may not prove to be very qualitative. In this paper we aim at discretising activity related durations using different clustering algorithms. We explore the possibility of discretising duration data through the use of rudimentary clustering algorithms such as visual inspection to more established methods such as model based clustering. In addition, a probabilistic model is built that predicts both person and activities from the observed values of sensor sequence, time and discrete duration values. Each of the models created is compared in terms of its performance in the prediction of activities. Following analysis of the results attained it has been found that irrespective of the clustering algorithm used for duration discretisation, incorporating the duration information increases the prediction performance. Prediction accuracy was improved by almost 3% when the model was built incorporating durations. PMID:23000560

Chaurasia, Priyanka; McClean, Sally; Scotney, Bryan; Nugent, Chris

2012-01-01

174

Quantitative Analysis of QRS Detection Algorithms Based on the First Derivative of the ECG  

Microsoft Academic Search

Accurate processing of electrocardiogram (ECG) signals requires a sensitive and robust QRS detection method. In this study, three methods are quantitatively compared using a similar algorithm structure but applying different transforms to the differentiated ECG. The three transforms used are the Hilbert transformer, the squaring function, and a second discrete derivative stage. The first two have been widely used in

Natalia M. Arzeno; Chi-Sang Poon; Zhi-De Deng

2006-01-01

175

A Comparison Of Three QRS Detection Algorithms Using The ABA ECG Database  

Microsoft Academic Search

Many real-time QRS detection algorithms have been proposed in the literature. However, these algorithms usually either exhibit too long a response time or lack robustness. An algorithm has been developed which offers a balance between these two traits, with a very low response time yet with performance comparable to the slower algorithms. Using the AHA ECG database, this algorithm is

Seth Suppappola; Ying Sun

1991-01-01

176

Efficient QRS detection in wearable ECG devices for body sensor network  

Microsoft Academic Search

This paper presented an efficient QRS detection algorithm for wearable ECG devices used in body sensor network. The algorithm is based on interpolated finite impulse response filter and an approximated envelope to remove motion artifact in ECG signals captured from wearable devices. Evaluation of the performance was based on both MIT-BIH ECG database and ECG signals from wearable devices. It

Fei Zhang; Ying Wei; Yong Lian

2008-01-01

177

Simultaneous QRS detection and feature extraction using simple matched filter basis functions  

Microsoft Academic Search

A simple, easily implemented method is presented for extracting from an electrocardiogram (ECG) features describing QRS morphology. Tests using the American Heart Association (AHA) database indicate that these features are successful at enabling premature ventricular contractions (PVCs) to be associated with other PVCs on the basis of morphology 99% of the time. The good performance of this method suggests that

D. T. Kaplan

1990-01-01

178

A moving average based filtering system with its application to real-time QRS detection  

Microsoft Academic Search

This paper presents a novel real-time QRS detection algorithm designed based on a simple moving average filter. The proposed algorithm demands no redundant preprocessing step, thus allowing a simple architecture for its implementation as well as low computational cost. Algorithm performance was validated against a subset of the MIT-BIH arrhythmia database. Consequently, numerical results showed that the proposed algorithm correctly

H. C. Chen; S. W. Chen

2003-01-01

179

QRS Detection Based on Multiscale Mathematical Morphology for Wearable ECG Devices in Body Area Networks  

Microsoft Academic Search

A novel wearable electrocardiograph (ECG) QRS detection algorithm for wearable ECG devices in body area networks is presented in this paper, which utilizes the multistage multiscale mathematical morphology filtering to suppress the impulsive noise and uses the multiframe differential modulus accumulation to remove the baseline drift and enhance the signal. The proposed algorithm, verified with data from the MIT\\/BIH Arrhythmia

Fei Zhang; Yong Lian

2009-01-01

180

Embedded real-time QRS detection algorithm for pervasive cardiac care system  

Microsoft Academic Search

The emergence and development of pervasive computing technology leads to the revolution of remote cardiac care and also brings forth challenges to the automatic ECG diagnosis (AED) techniques. Due to the high resource requirements, traditional AED methods are unsuitable for pervasive cardiac care (PCC) applications. This paper proposes an embedded real-time QRS detection algorithm dedicated to PCC systems. By analyzing

H.-Y. Zhou; K.-M. Hou

2008-01-01

181

Fetal QRS detection and heart rate estimation: a wavelet-based approach.  

PubMed

Fetal heart rate monitoring is used for pregnancy surveillance in obstetric units all over the world but in spite of recent advances in analysis methods, there are still inherent technical limitations that bound its contribution to the improvement of perinatal indicators. In this work, a previously published wavelet transform based QRS detector, validated over standard electrocardiogram (ECG) databases, is adapted to fetal QRS detection over abdominal fetal ECG. Maternal ECG waves were first located using the original detector and afterwards a version with parameters adapted for fetal physiology was applied to detect fetal QRS, excluding signal singularities associated with maternal heartbeats. Single lead (SL) based marks were combined in a single annotator with post processing rules (SLR) from which fetal RR and fetal heart rate (FHR) measures can be computed. Data from PhysioNet with reference fetal QRS locations was considered for validation, with SLR outperforming SL including ICA based detections. The error in estimated FHR using SLR was lower than 20 bpm for more than 80% of the processed files. The median error in 1 min based FHR estimation was 0.13 bpm, with a correlation between reference and estimated FHR of 0.48, which increased to 0.73 when considering only records for which estimated FHR > 110 bpm. This allows us to conclude that the proposed methodology is able to provide a clinically useful estimation of the FHR. PMID:25070210

Almeida, Rute; Gonçalves, Hernâni; Bernardes, Joăo; Rocha, Ana Paula

2014-08-01

182

QRS scoring with the Mason-Likar lead system at rest and during ischaemia.  

PubMed

The stability of the post-infarction simplified 29-point Selvester QRS score during maximal exercise testing was studied using both standard 12 and Mason-Likar (modified standard, M-L) ECG lead systems. Thirty-eight patients participated in the standard exercise test (mean interval after single infarction 4 months) and a total of 54 patients underwent exercise 201thallium emission tomography with M-L lead system 2 months later. None had electrocardiographic features complicating the scoring. There were no significant differences between the (paired) mean QRS scores, except between the M-L score at rest (2.3 +/- 2.4) and at exercise (3.2 +/- 2.6, P less than 0.01). The correlation coefficient (r) between resting scores was 0.87, between rest and exercise 0.90 (standard leads) and 0.80 (M-L leads). In 78% nuclear imaging revealed ischaemia, but this had no significant effect on the mean scores or correlation between rest and exercise scores. It is concluded that the QRS score is relatively stable during exercise with standard leads if the limb leads are recorded immediately after the exercise. Scoring with the M-L lead system is somewhat inaccurate, especially during exercise, and is not recommended for stratification of clinical risk. The QRS score is protected against ischaemia, which emphasizes its value as an independent prognostic tool. PMID:1934938

Walamies, M

1991-09-01

183

Atlas of paced body surface QRS integral maps for localization of the site of origin of postinfarction ventricular tachycardia.  

PubMed

Current mapping during radiofrequency (RF) catheter ablation of postinfarction ventricular tachycardia (VT) is based primarily on the use of single-site mapping techniques. Although such techniques are highly suitable for distinguishing the ultimate site where RF energy is delivered by enabling detailed localization of the exit site or critical component of the VT reentrant circuit, they are time-consuming and inefficient for initial rapid identification of the arrhythmogenic target area. This study features the design and preliminary clinical application of a new noninvasive method that is aimed at speeding up the initial phase of the VT mapping procedure. This method is based on the use of an atlas of 62-lead body surface QRS integral map patterns that was previously developed using left ventricular pace mapping in patients with remote anterior or inferior myocardial infarction. The atlas contains 18 and 22 different paced QRS integral map patterns obtained in patients with previous anterior or inferior myocardial infarction, respectively. Each specific QRS pattern in the atlas provides a unique infarct-specific spatial electrocardiographic representation of the onset of ectopic ventricular activation in a circumscribed endocardial segment of the left ventricle. Localization of the segment of VT origin is obtained by visually or mathematically comparing the QRS integral map recorded during VT with one of the two sets of paced QRS integral maps contained within the atlas with the purpose of selecting the best matching paced QRS integral map pattern.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7884343

SippensGroenewegen, A; Hauer, R N; van Hemel, N M; Janse, M J; Robles de Medina, E O

1994-01-01

184

Fast QRS detection with an optimized knowledge-based method: evaluation on 11 standard ECG databases.  

PubMed

The current state-of-the-art in automatic QRS detection methods show high robustness and almost negligible error rates. In return, the methods are usually based on machine-learning approaches that require sufficient computational resources. However, simple-fast methods can also achieve high detection rates. There is a need to develop numerically efficient algorithms to accommodate the new trend towards battery-driven ECG devices and to analyze long-term recorded signals in a time-efficient manner. A typical QRS detection method has been reduced to a basic approach consisting of two moving averages that are calibrated by a knowledge base using only two parameters. In contrast to high-accuracy methods, the proposed method can be easily implemented in a digital filter design. PMID:24066054

Elgendi, Mohamed

2013-01-01

185

Fast QRS Detection with an Optimized Knowledge-Based Method: Evaluation on 11 Standard ECG Databases  

PubMed Central

The current state-of-the-art in automatic QRS detection methods show high robustness and almost negligible error rates. In return, the methods are usually based on machine-learning approaches that require sufficient computational resources. However, simple-fast methods can also achieve high detection rates. There is a need to develop numerically efficient algorithms to accommodate the new trend towards battery-driven ECG devices and to analyze long-term recorded signals in a time-efficient manner. A typical QRS detection method has been reduced to a basic approach consisting of two moving averages that are calibrated by a knowledge base using only two parameters. In contrast to high-accuracy methods, the proposed method can be easily implemented in a digital filter design.

Elgendi, Mohamed

2013-01-01

186

Implications of progressive aberrancy versus true fusion for diagnosis of wide complex tachycardia.  

PubMed

At the onset of wide complex tachycardia, beats with intermediate morphologies sometimes occur between the normally conducted beats and the wide complex tachycardia QRS. Intermediate beats could be true fusion; however, progressive aberrancy has been reported to mimic true fusion. To evaluate the incidence of progressive aberrancy, wide complex tachycardia tracings were collected in which an intermediate beat was noted at the onset. When the associated electrocardiographic findings were diagnosed as supraventricular tachycardia, the beat was identified as progressive aberrancy. When diagnosed as ventricular tachycardia, the intermediate beat was identified as true fusion. Electrocardiographic criteria were then identified from this cohort to identify the distinguishing features between progressive aberrancy and true fusion. Of 24 episodes of wide complex tachycardia, 17 (71%) were identified as true fusion and 7 (29%) as progressive aberrancy. The QRS duration of the intermediate and wide complex tachycardia beats were shorter with progressive aberrancy than with true fusion (109 ± 23 ms vs 131 ± 20 ms, p <0.023; and 139 ± 21 ms vs 177 ± 24 ms, p <0.001, respectively). In progressive aberrancy (n = 3), the PR interval of the intermediate beat was always greater than the PR interval of the normally conducted beat. In contrast, in true fusion (n = 11), the PR interval of the intermediate beat was always less than the PR interval of the normally conducted beat. Multiple intermediate beats were present in 4 of 7 cases of progressive aberrancy and in 0 of 17 cases of true fusion. In conclusion, true fusion is the most common explanation for intermediate beats, but progressive aberrancy occurs a significant proportion of the time (29%). The identified criteria will be helpful in differentiating ventricular tachycardia from supraventricular tachycardia with aberrancy as a cause of wide complex tachycardia. PMID:21529737

Greenstein, Eugene; Goldberger, Jeffrey J

2011-07-01

187

Does Maturity Affect Cephalic Perfusion and T/QRS Ratio during Prolonged Umbilical Cord Occlusion in Fetal Sheep?  

PubMed Central

T/QRS ratio monitoring is used to help identify fetal asphyxia. However, immature animals have greater capacity to maintain blood pressure during severe asphyxia, raising the possibility that they may show an attenuated T/QRS increase during asphyxia. Chronically instrumented fetal sheep at 0.6 of gestation (0.6?GA; n = 12), 0.7?GA (n = 12), and 0.8?GA (n = 8) underwent complete umbilical cord occlusion for 30?min, 25?min, or 15?min, respectively. Cord occlusion was associated with progressive metabolic acidosis and initial hypertension followed by severe hypotension, with a more rapid fall in mean arterial blood pressure (MAP) and carotid blood flow (CaBF) with advancing gestation. T/QRS ratio rose after occlusion more rapidly at 0.8?GA than in immature fetuses, to a similar final peak at all ages, followed by a progressive fall that was slower at 0.8?GA than in the immature fetuses. The increase in T/QRS ratio correlated with initial hypertension at 0.8?GA (P < 0.05, R2 = 0.38), and conversely, its fall correlated closely with falling MAP in all gestational groups (P < 0.01, R2 = 0.67). In conclusion, elevation of the T/QRS ratio is an index of onset of severe asphyxia in the last third of gestation, but not of fetal compromise.

Drury, Paul P.; Gunn, Eleanor R.; Bennet, Laura; Gunn, Alistair J.

2014-01-01

188

Implications of Franciscan Complex graywacke geochemistry for sediment transport, provenance determination, burial-exposure duration, and fluid exchange with cosubducted metabasites  

NASA Astrophysics Data System (ADS)

of graywacke provenance has long been used to evaluate the record of tectonic process in orogenic belts. Our geochemical data from graywackes of the Franciscan subduction complex, California, show that the connection between sedimentary record and geologic processes may be more complex than previously believed. Trace elements and Nd-Sr-Pb isotopes of Franciscan graywackes indicate two sources types. One group lacking negative Eu anomaly (Eu/Eu* > 0.9), shows slightly concave-up heavy rare earth elements, arc-like trace element patterns, and western Pacific island arc-like Pb isotopes, reflecting derivation from older accreted oceanic-arc terranes in the Sierra Nevada-Klamath Mountains. The other group displays small negative Eu anomalies, with trace element patterns resembling post-Archean Australian shale and Pb isotopes similar to Jurassic-Cretaceous Sierran batholith. There is no systematic separation of these two groups by depositional ages. Thus, geochemistry of the graywackes may partly reflect variation in location of sediment delivery systems, rather than solely reflecting evolution of the neighboring arc. Variation of Nd-Sr isotopes with stratigraphic-age for the graywackes mimics the trends of the coeval Great Valley Group clastic-rocks, suggesting that (1) they share the same sediment sources, (2) there are no "exotic" sediment sources that fed the Franciscan trench, and (3) burial-exposure cycles for Franciscan clastic rocks were comparatively brief. Comparison of Franciscan graywacke and metabasite geochemistry corroborates earlier conclusions that metabasites had little or no chemical exchange with fluids from cosubducted graywacke. Detrital zircon age populations, major element chemistry, and detrital framework modes, when compared to our data suggest that the former three parameters underrepresent the mafic component of clastic sediment provenance.

Ghatak, Arundhuti; Basu, Asish R.; Wakabayashi, John

2013-09-01

189

Memory consolidation for duration.  

PubMed

Humans and animals encode and store in memory elapsed intervals as evidenced through their temporal expectancies. However, there are very few experimental studies on long-term memory of duration. The aim of this original study was to examine the consolidation process for duration and its effect on time judgement. In our study, memory of duration was tested in humans with a temporal generalization task. Consolidation was assessed by means of a 15-min nontemporal interference task introduced at different delays after the initial learning of a 4-s standard duration. The results showed that (a) when tested 24?hours after the learning phase, memory of the 4-s duration was disrupted (less precision and lengthening effect) if the interference task was introduced 30-45?min after learning; (b) no disruption was observed when memory was tested immediately after the interference task; and (c) there was a temporal gradient of the disruptive interference effect within the first hour after learning. Overall, these results fulfil the key criteria for the inference of a synaptic/cellular consolidation process and thus demonstrate that, as is the case for other memories, memory of duration undergoes a consolidation process that lasts at least one hour. PMID:24279983

Cocenas-Silva, Raquel; Bueno, José Lino Oliveira; Doyčre, Valérie; Droit-Volet, Sylvie

2014-07-01

190

Therapeutic efficacy of liposomal clofazimine against Mycobacterium avium complex in mice depends on size of initial inoculum and duration of infection.  

PubMed Central

The therapeutic efficacy of liposomal clofazimine (L-CLF) against Mycobacterium avium complex (MAC) was evaluated in the acute and chronic infection models of the beige mouse (C57BL/6J bgj bgj). The maximum tolerated dose of L-CLF was inversely proportional to the infection level. L-CLF showed higher antibacterial activity than free clofazimine. Treatment with 25 mg of L-CLF per kg of body weight (intravenously) was started at days 1, 8, 15, and 22 postinfection and was studied at three levels of MAC infection (10(4), 10(5), and 10(6) bacilli/mouse). L-CLF treatment caused a significant (P < 0.05 to 0.001) reduction in the numbers of viable bacteria in lung, liver, and spleen at all infection levels, irrespective of time of treatment. However, the best results were obtained when an already established infection was treated (day 22). The organ-related differences in response to the treatment were also affected by the level of infection. A marked reduction in the numbers of CFU was observed in the lungs of mice with lower infection levels, whereas liver and spleen were treated more efficiently at higher infection levels. These studies might help in evaluations of host responses to therapy.

Kansal, R G; Gomez-Flores, R; Sinha, I; Mehta, R T

1997-01-01

191

Case Report Cardiac Pacemaker Battery Discharge After External Electrical Cardioversion for Broad QRS Complex Tachycardia  

Microsoft Academic Search

External electrical cardioversion or defibrillation may be necessary in patients with implanted cardiac pacemaker (PM) or implantable cardioverter defibrillator (ICD). Sudden discharge of high electrical energy employed in direct current (DC) transthoracic countershock may damage the PM\\/ICD system resulting in a series of possible device malfunctions. For this reason, when defibrillation or cardioversion must be attempted in a patient with

Martino Annamaria; Scapigliati Andrea; Casella Michela; Sanna Tommaso; Pelargonio Gemma; Dello Russo Antonio; Zamparelli Roberto; Paulis Stefano; Bellocci Fulvio; Schiavello Rocco

192

A robust physiology-based source separation method for QRS detection in low amplitude fetal ECG recordings.  

PubMed

The use of the non-invasively obtained fetal electrocardiogram (ECG) in fetal monitoring is complicated by the low signal-to-noise ratio (SNR) of ECG signals. Even after removal of the predominant interference (i.e. the maternal ECG), the SNR is generally too low for medical diagnostics, and hence additional signal processing is still required. To this end, several methods for exploiting the spatial correlation of multi-channel fetal ECG recordings from the maternal abdomen have been proposed in the literature, of which principal component analysis (PCA) and independent component analysis (ICA) are the most prominent. Both PCA and ICA, however, suffer from the drawback that they are blind source separation (BSS) techniques and as such suboptimum in that they do not consider a priori knowledge on the abdominal electrode configuration and fetal heart activity. In this paper we propose a source separation technique that is based on the physiology of the fetal heart and on the knowledge of the electrode configuration. This technique operates by calculating the spatial fetal vectorcardiogram (VCG) and approximating the VCG for several overlayed heartbeats by an ellipse. By subsequently projecting the VCG onto the long axis of this ellipse, a source signal of the fetal ECG can be obtained. To evaluate the developed technique, its performance is compared to that of both PCA and ICA and to that of augmented versions of these techniques (aPCA and aICA; PCA and ICA applied on preprocessed signals) in generating a fetal ECG source signal with enhanced SNR that can be used to detect fetal QRS complexes. The evaluation shows that the developed source separation technique performs slightly better than aPCA and aICA and outperforms PCA and ICA and has the main advantage that, with respect to aPCA/PCA and aICA/ICA, it performs more robustly. This advantage renders it favorable for employment in automated, real-time fetal monitoring applications. PMID:20530846

Vullings, R; Peters, C H L; Hermans, M J M; Wijn, P F F; Oei, S G; Bergmans, J W M

2010-07-01

193

Flow-duration curves  

USGS Publications Warehouse

The flow-duration curve is a cumulative frequency curve that shows the percent of time specified discharges were equaled or exceeded during a given period. It combines in one curve the flow characteristics of a stream throughout the range of discharge, without regard to the sequence of occurrence. If the period upon which the curve is based represents the long-term flow of a stream, the curve may be used to predict the distribution of future flows for water- power, water-supply, and pollution studies. This report shows that differences in geology affect the low-flow ends of flow-duration curves of streams in adjacent basins. Thus, duration curves are useful in appraising the geologic characteristics of drainage basins. A method for adjusting flow-duration curves of short periods to represent long-term conditions is presented. The adjustment is made by correlating the records of a short-term station with those of a long-term station.

Searcy, James Kincheon

1959-01-01

194

When Deriving the Spatial QRS-T Angle from the 12-lead ECG, which Transform is More Frank: Regression or Inverse Dower?  

NASA Technical Reports Server (NTRS)

Our primary objective was to ascertain which commonly used 12-to-Frank-lead transformation yields spatial QRS-T angle values closest to those obtained from simultaneously collected true Frank-lead recordings. Simultaneous 12-lead and Frank XYZ-lead recordings were analyzed for 100 post-myocardial infarction patients and 50 controls. Relative agreement, with true Frank-lead results, of 12-to-Frank-lead transformed results for the spatial QRS-T angle using Kors regression versus inverse Dower was assessed via ANOVA, Lin s concordance and Bland-Altman plots. Spatial QRS-T angles from the true Frank leads were not significantly different than those derived from the Kors regression-related transformation but were significantly smaller than those derived from the inverse Dower-related transformation (P less than 0.001). Independent of method, spatial mean QRS-T angles were also always significantly larger than spatial maximum (peaks) QRS-T angles. Spatial QRS-T angles are best approximated by regression-related transforms. Spatial mean and spatial peaks QRS-T angles should also not be used interchangeably.

Schlegel, Todd T.; Cortez, Daniel

2010-01-01

195

Usefulness of Electrocardiographic QRS/T Angles With Versus Without Bundle Branch Blocks to Predict Heart Failure (from the Atherosclerosis Risk in Communities Study).  

PubMed

Repolarization abnormalities in the setting of bundle branch blocks (BBB) are generally ignored. We used Cox regression models to determine hazard ratios (HRs) with 95% confidence intervals (CIs) for incident heart failure (HF) associated with wide spatial and frontal QRS/T angle (upper twenty-fifth percentile of each) in men and women with and without BBB. This analysis included 14,478 participants (54.6% women, 26.4% blacks, 377 [2.6%] with BBB) from the Atherosclerosis Risk in Communities Study who were free of HF at baseline. Using No-BBB with normal spatial QRS/T angle as the reference group, the risk for HF in multivariable adjusted models was increased 51% for No-BBB with wide spatial QRS/T angle (HR 1.51, 95% CI 1.37 to 1.66), 48% for BBB with normal spatial QRS/T angle (HR 1.48, 95% CI 1.17 to 1.88), and the risk for incident HF was increased more than threefold for BBB with wide spatial QRS/T angle (HR 3.37, 95% CI 2.47 to 4.60). The results were consistent across subgroups by gender. Similar results were observed for the frontal plane QRS/T angle. In the pooled BBB group excluding right BBB, a positive T wave in lead aVR and heart rate 70 bpm and higher were also potent predictors of incident HF similar to the QRS/T angles. In conclusion, both BBB and wide QRS/T angles are predictive of HF, and concomitant presence of both carries a much higher risk than for either predictor alone. These findings suggest that repolarization abnormalities in the setting of BBB should not be considered benign or an expected consequence of BBB. PMID:24929625

Zhang, Zhu-Ming; Rautaharju, Pentti M; Prineas, Ronald J; Loehr, Laura; Rosamond, Wayne; Soliman, Elsayed Z

2014-08-01

196

Long duration flights management  

NASA Astrophysics Data System (ADS)

Long duration flights (LDF) require a special management to take the best decisions in terms of ballast consumption and instant of separation. As a contrast to short duration flights, where meteorological conditions are relatively well known, for LDF we need to include the meteorological model accuracy in trajectory simulations. Dispersions on the fields of model (wind, temperature and IR fluxes) could make the mission incompatible with safety rules, authorized zones and others flight requirements. Last CNES developments for LDF act on three main axes: 1. Although ECMWF-NCEP forecast allows generating simulations from a 4D point (altitude, latitude, longitude and UT time), result is not statistical, it is determinist. To take into account model dispersion a meteorological NCEP data base was analyzed. A comparison between Analysis (AN) and Forecast (FC) for the same time frame had been done. Result obtained from this work allows implementing wind and temperature dispersions on balloon flight simulator. 2. For IR fluxes, NCEP does not provide ascending IR fluxes in AN mode but only in FC mode. To obtain the IR fluxes for each time frame, satellite images are used. A comparison between FC and satellites measurements had been done. Results obtained from this work allow implementing flux dispersions on balloon flight simulator. 3. An improved cartography containing a vast data base had been included in balloon flight simulator. Mixing these three points with balloon flight dynamics we have obtained two new tools for observing balloon evolution and risk, one of them is called ASTERISK (Statistic Tool for Evaluation of Risk) for calculations and the other one is called OBERISK (Observing Balloon Evolution and Risk) for visualization. Depending on the balloon type (super pressure, zero pressure or MIR) relevant information for the flight manager is different. The goal is to take the best decision according to the global situation to obtain the largest flight duration with a minimum risk for population. Telemetry system is based on satellite communication technologies. Housekeeping data and GPS data are transferred to the Ground Station by IRIDIUM network. Gondola is interrogated automatically each hour and all data stocked onboard are downloaded to ground station. Communication takes a few minutes to transfer all data stocked from last request. Tools had been used in SCOUT-MIR campaign 2008 for the first time. The results obtained encourage CNES teams to improve ergonomics and functionalities of these prototype.

Sosa-Sesma, Sergio; Letrenne, Gérard; Spel, Martin; Charbonnier, Jean-Marc

197

Impact of response duration on multisensory integration.  

PubMed

Multisensory neurons in the superior colliculus (SC) have been shown to have large receptive fields that are heterogeneous in nature. These neurons have the capacity to integrate their different sensory inputs, a process that has been shown to depend on the physical characteristics of the stimuli that are combined (i.e., spatial and temporal relationship and relative effectiveness). Recent work has highlighted the interdependence of these factors in driving multisensory integration, adding a layer of complexity to our understanding of multisensory processes. In the present study our goal was to add to this understanding by characterizing how stimulus location impacts the temporal dynamics of multisensory responses in cat SC neurons. The results illustrate that locations within the spatial receptive fields (SRFs) of these neurons can be divided into those showing short-duration responses and long-duration response profiles. Most importantly, discharge duration appears to be a good determinant of multisensory integration, such that short-duration responses are typically associated with a high magnitude of multisensory integration (i.e., superadditive responses) while long-duration responses are typically associated with low integrative capacity. These results further reinforce the complexity of the integrative features of SC neurons and show that the large SRFs of these neurons are characterized by vastly differing temporal dynamics, dynamics that strongly shape the integrative capacity of these neurons. PMID:22896723

Ghose, Dipanwita; Barnett, Zachary P; Wallace, Mark T

2012-11-01

198

Long Duration Exposure Facility  

NASA Technical Reports Server (NTRS)

This is an onboard photo of the deployment of the Long Duration Exposure Facility (LDEF) from the cargo bay of the Space Shuttle Orbiter Challenger STS-41C mission, April 7, 1984. After a five year stay in space, the LDEF was retrieved during the STS-32 mission by the Space Shuttle Orbiter Columbia in January 1990 and was returned to Earth for close examination and analysis. The LDEF was designed by the Marshall Space Flight Center (MSFC) to test the performance of spacecraft materials, components, and systems that have been exposed to the environment of micrometeoroids, space debris, radiation particles, atomic oxygen, and solar radiation for an extended period of time. Proving invaluable to the development of both future spacecraft and the International Space Station (ISS), the LDEF carried 57 science and technology experiments, the work of more than 200 investigators, 33 private companies, 21 universities, 7 NASA centers, 9 Department of Defense laboratories, and 8 forein countries.

1984-01-01

199

A vector-free ECG interpretation with P, QRS & T waves as unbalanced transitions between stable configurations of the heart electric field during P-R, S-T & T-P segments  

PubMed Central

Since cell membranes are weak sources of electrostatic fields, this ECG interpretation relies on the analogy between cells and electrets. It is here assumed that cell-bound electric fields unite, reach the body surface and the surrounding space and form the thoracic electric field that consists from two concentric structures: the thoracic wall and the heart. If ECG leads measure differences in electric potentials between skin electrodes, they give scalar values that define position of the electric field center along each lead. Repolarised heart muscle acts as a stable positive electric source, while depolarized heart muscle produces much weaker negative electric field. During T-P, P-R and S-T segments electric field is stable, only subtle changes are detectable by skin electrodes. Diastolic electric field forms after ventricular depolarization (T-P segments in the ECG recording). Telediastolic electric field forms after the atria have been depolarized (P-Q segments in the ECG recording). Systolic electric field forms after the ventricular depolarization (S-T segments in the ECG recording). The three ECG waves (P, QRS and T) can then be described as unbalanced transitions of the heart electric field from one stable configuration to the next and in that process the electric field center is temporarily displaced. In the initial phase of QRS, the rapidly diminishing septal electric field makes measured potentials dependent only on positive charges of the corresponding parts of the left and the right heart that lie within the lead axes. If more positive charges are near the "DOWN" electrode than near the "UP" electrode, a Q wave will be seen, otherwise an R wave is expected. Repolarization of the ventricular muscle is dampened by the early septal muscle repolarization that reduces deflection of T waves. Since the "UP" electrode of most leads is near the usually larger left ventricle muscle, T waves are in these leads positive, although of smaller amplitude and longer duration than the QRS wave in the same lead. The proposed interpretation is applied to bundle branch blocks, fascicular (hemi-) blocks and changes during heart muscle ischemia.

2014-01-01

200

Effect of QRS morphology on clinical event reduction with cardiac resynchronization therapy: Meta-analysis of randomized controlled trials  

PubMed Central

Background Cardiac resynchronization therapy (CRT) is effective in reducing clinical events in systolic heart failure patients with a wide QRS. Previous retrospective studies suggest only patients with QRS prolongation due to a left bundle-branch block (LBBB) benefit from CRT. Our objective was to examine this by performing a meta-analysis of all randomized controlled trials of CRT. Methods Systematic searches of MEDLINE and the Food and Drug Administration official website were conducted for randomized controlled CRT trials. Trials reporting adverse clinical events (eg, all-cause mortality, heart failure hospitalizations) according to QRS morphology were included in the meta-analysis. Results Four randomized trials totaling 5,356 patients met the inclusion criteria. In patients with LBBB at baseline, there was a highly significant reduction in composite adverse clinical events with CRT (RR = 0.64 [95% CI (0.52–0.77)], P = .00001). However no such benefit was observed for patients with non-LBBB conduction abnormalities (RR = 0.97 [95% CI (0.82–1.15)], P = .75). When examined separately, there was no benefit in patients with right-bundle branch block (RR = 0.91 [95% CI (0.69–1.20)], P = .49) or non-specific intraventricular conduction delay (RR = 1.19 [95% CI (0.87–1.63)], P = .28). There was no heterogeneity among the clinical trials with regards to the lack of benefit in non-LBBB patients (I2 = 0%). When directly compared, the difference in effect of CRT between LBBB versus non-LBBB patients was highly statistically significant (P = .0001 by heterogeneity analysis). Conclusions While CRT was very effective in reducing clinical events in patients with LBBB, it did not reduce such events in patients with wide QRS due to other conduction abnormalities.

Sipahi, Ilke; Chou, Josephine C.; Hyden, Marshall; Rowland, Douglas Y.; Simon, Daniel I.; Fang, James C.

2014-01-01

201

Long duration ash probe  

DOEpatents

A long duration ash probe includes a pressure shell connected to a port in a combustor with a sample coupon mounted on a retractable carriage so as to retract the sample coupon within the pressure shell during soot blowing operation of the combustor. A valve mounted at the forward end of the pressure shell is selectively closeable to seal the sample coupon within the shell, and a heating element in the shell is operable to maintain the desired temperature of the sample coupon while retracted within the shell. The carriage is operably mounted on a pair of rails within the shell for longitudinal movement within the shell. A hollow carrier tube connects the hollow cylindrical sample coupon to the carriage, and extends through the carriage and out the rearward end thereof. Air lines are connected to the rearward end of the carrier tube and are operable to permit coolant to pass through the air lines and thence through the carrier tube to the sample coupon so as to cool the sample coupon. 8 figs.

Hurley, J.P.; McCollor, D.P.; Selle, S.J.

1994-07-26

202

Long duration ash probe  

DOEpatents

A long duration ash probe includes a pressure shell connected to a port in a combustor with a sample coupon mounted on a retractable carriage so as to retract the sample coupon within the pressure shell during sootblowing operation of the combustor. A valve mounted at the forward end of the pressure shell is selectively closeable to seal the sample coupon within the shell, and a heating element in the shell is operable to maintain the desired temperature of the sample coupon while retracted within the shell. The carriage is operably mounted on a pair of rails within the shell for longitudinal movement within the shell. A hollow carrier tube connects the hollow cylindrical sample coupon to the carriage, and extends through the carriage and out the rearward end thereof. Air lines are connected to the rearward end of the carrier tube and are operable to permit coolant to pass through the air lines and thence through the carrier tube to the sample coupon so as to cool the sample coupon.

Hurley, John P. (Grand Forks, ND); McCollor, Don P. (Grand Forks, ND); Selle, Stanley J. (Grand Forks, MN)

1994-01-01

203

Quantitative analysis of QRS detection algorithms based on the first derivative of the ECG.  

PubMed

Accurate processing of electrocardiogram (ECG) signals requires a sensitive and robust QRS detection method. In this study, three methods are quantitatively compared using a similar algorithm structure but applying different transforms to the differentiated ECG. The three transforms used are the Hilbert transformer, the squaring function, and a second discrete derivative stage. The first two have been widely used in ECG and heart rate variability analysis while the second derivative method aims to explain the success of the Hilbert transform. The algorithms were compared in terms of the number of false positive and false negative detections produced for records of the MIT/BIH Arrhythmia Database. The Hilbert transformer and the squaring function both produced a sensitivity and positive predictivity of over 99%, though the squaring function had a lower overall detection error rate. The second derivative resulted in the highest overall detection error rate. Different algorithms performed better for diverse ECG characteristics; suggesting that an algorithm can be specified for different recordings, the algorithms can be combined based on each one's characteristics to determine a new more accurate method, or an additional detection stage can be added to reduce the number of false negatives. PMID:17946480

Arzeno, Natalia M; Poon, Chi-Sang; Deng, Zhi-De

2006-01-01

204

Is subjective duration a signature of coding efficiency?  

PubMed Central

Perceived duration is conventionally assumed to correspond with objective duration, but a growing literature suggests a more complex picture. For example, repeated stimuli appear briefer in duration than a novel stimulus of equal physical duration. We suggest that such duration illusions appear to parallel the neural phenomenon of repetition suppression, and we marshal evidence for a new hypothesis: the experience of duration is a signature of the amount of energy expended in representing a stimulus, i.e. the coding efficiency. This novel hypothesis offers a unified explanation for almost a dozen illusions in the literature in which subjective duration is modulated by properties of the stimulus such as size, brightness, motion and rate of flicker.

Eagleman, David M.; Pariyadath, Vani

2009-01-01

205

Impacts of Coulomb Interactions on the Magnetic Responses of Excitonic Complexes in Single Semiconductor Nanostructures  

PubMed Central

We report on the diamagnetic responses of different exciton complexes in single InAs/GaAs self-assembled quantum dots (QDs) and quantum rings (QRs). For QDs, the imbalanced magnetic responses of inter-particle Coulomb interactions play a crucial role in the diamagnetic shifts of excitons (X), biexcitons (XX), and positive trions (X?). For negative trions (X?) in QDs, anomalous magnetic responses are observed, which cannot be described by the conventional quadratic energy shift with the magnetic field. The anomalous behavior is attributed to the apparent change in the electron wave function extent after photon emission due to the strong Coulomb attraction by the hole in its initial state. In QRs, the diamagnetic responses of X and XX also show different behaviors. Unlike QDs, the diamagnetic shift of XX in QRs is considerably larger than that of X. The inherent structural asymmetry combined with the inter-particle Coulomb interactions makes the wave function distribution of XX very different from that of X in QRs. Our results suggest that the phase coherence of XX in QRs may survive from the wave function localization due to the structural asymmetry or imperfections.

2010-01-01

206

Uncertainty and Labor Contract Durations.  

National Technical Information Service (NTIS)

This paper provides an empirical investigation into the relationship between ex ante U.S. labor contract durations and uncertainty over the period 1970 to 1995. We construct measures of inflation uncertainty as well as aggregate nominal and real uncertain...

R. Rich J. Tracy

2000-01-01

207

JACEE long duration balloon flights  

SciTech Connect

JACEE balloon-borne emulsion chamber detectors are used to observe the spectra and interactions of cosmic ray protons and nuclei in the energy range 1-100A TeV. Experience with long duration mid-latitude balloon flights and characteristics of the detector system that make it ideal for planned Antarctic balloon flights are discussed. 5 refs., 2 figs.

Burnett, T.; Iwai, J.; Lord, J.J.; Strausz, S.; Wilkes, R.J. (Washington Univ., Seattle, WA (USA)); Dake, S.; Oda, H. (Kobe Univ. (Japan)); Miyamura, O. (Osaka Univ. (Japan)); Fuki, M. (Matsusho Gakuen Junior Coll., Matsumoto (Japan)); Jones, W.V. (National Aeronautics and Space Administration, Washington, DC (USA)); Gregory, J.; Hayashi, T.; Takahashi, U. (Alabama Univ., Huntsville, AL (USA)); Tominaga,

1989-01-01

208

Optimal Duration of Magazine Promotions  

Microsoft Academic Search

The planning of promotions and other marketing events frequently requires manufacturers to make decisions about the optimal duration of these activities. Yet manufacturers often lack the support tools for decision making. We assume that customer decisions at the aggregated level follow a state-dependent Markov process. On the basis of the expected economic return associated with dynamic response to stimuli, we

Mercedes Esteban-Bravo; José M. Múgica; Jose M. Vidal-Sanz

2005-01-01

209

OPTIMAL DURATION OF MAGAZINE PROMOTIONS  

Microsoft Academic Search

The planning of promotions and other marketing events frequently requires manufacturers to make decisions about the optimal duration of these activities. Yet manufacturers often lack the support tools for decision making. We assume that customer decisions at the aggregated level follow a state-dependent Markov process. On the basis of the expected economic return associated with dynamic response to stimuli, we

Mercedes Esteban-Bravo; Jose M. Mugica; Jose M. Vidal-Sanz

2004-01-01

210

Duration of an Elastic Collision  

ERIC Educational Resources Information Center

With a pedagogical goal, this paper deals with a study of the duration of an elastic collision of an inflatable spherical ball on a planar surface suitable for undergraduate studies. First, the force generated by the deformed spherical ball is obtained under assumptions that are discussed. The study of the motion of the spherical ball colliding…

de Izarra, Charles

2012-01-01

211

Sleep duration, asthma and obesity  

PubMed Central

Background Obesity is more prevalent in asthmatics. Short sleep duration is a novel risk factor for obesity in general populations. Objective We tested the association of sleep duration and asthma characteristics with obesity. Methods Adults at tertiary clinics were surveyed on asthma symptoms and habitual sleep duration. Medical records were used to assess asthma severity step (1-4), extract height and weight, current medications and diagnosed comorbid conditions. BMI?30 kg/m2 defined obesity. Habitual sleep was categorized as <6 (very short), 6 to <7h (short), 7-8h (normal), >8 to ?9h (long) and >9h (very long). Inhaled corticosteroid doses were categorized as low, moderate and high. Results Among 611 participants (mean BMI 30±8), 249 (41%) were obese. After adjustment for covariates, obesity was associated with short and very long sleep: as compared to normal sleepers, the odds of being obese were on average 66% higher ([95% Confidence Interval: 1.07-2.57], p=0.02) among short and 124% higher ([1.08-1.65], p=0.03) among very long sleepers, and the association with very short sleep approached significance (1.74 [0.96-3.14], p=0.06). Obesity was also significantly related to highest asthma step (1.87 [1.09-3.21], p=0.02) and psychopathology (1.64 [1.08-2.48], p=0.02), and a trend was seen with high dose inhaled corticosteroids (1.82 [0.93-3.56], p=0.08). Conclusions Obesity in asthmatics is associated with shorter and very long sleep duration, worse asthma severity, psychopathology, and high dose inhaled corticosteroids. Although this cross-sectional study cannot prove causality, we speculate that further investigation of sleep may provide new opportunities to reduce the rising prevalence of obesity among asthmatics.

Teodorescu, Mihaela; Polomis, David A.; Gangnon, Ronald E.; Consens, Flavia B.; Chervin, Ronald D.; Teodorescu, Mihai C.

2013-01-01

212

Vacancies, Hirings, and the Duration Function  

Microsoft Academic Search

While the matching function relates hirings (H) to vacancies (V) and unemployment, the duration function relates the average duration of vacancies as measured by V\\/H to unemployment. Shifts of the duration function are equivalent to shifts of the matching function but easier to interpret. Therefore, this paper focuses on the microfoundations of the duration function. We find, first, that outward

Ante Farm

2003-01-01

213

Some effects of duration on vowel recognition.  

PubMed

This study was designed to examine the role of duration in vowel perception by testing listeners on the identification of CVC syllables generated at different durations. Test signals consisted of synthesized versions of 300 utterances selected from a large, multitalker database of /hVd/ syllables [Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099-3111 (1995)]. Four versions of each utterance were synthesized: (1) an original duration set (vowel duration matched to the original utterance), (2) a neutral duration set (duration fixed at 272 ms, the grand mean across all vowels), (3) a short duration set (duration fixed at 144 ms, two standard deviations below the mean), and (4) a long duration set (duration fixed at 400 ms, two standard deviations above the mean). Experiment 1 used a formant synthesizer, while a second experiment was an exact replication using a sinusoidal synthesis method that represented the original vowel spectrum more precisely than the formant synthesizer. Findings included (1) duration had a small overall effect on vowel identity since the great majority of signals were identified correctly at their original durations and at all three altered durations; (2) despite the relatively small average effect of duration, some vowels, especially [see text] and [see text], were significantly affected by duration; (3) some vowel contrasts that differ systematically in duration, such as [see text], and [see text], were minimally affected by duration; (4) a simple pattern recognition model appears to be capable of accounting for several features of the listening test results, especially the greater influence of duration on some vowels than others; and (5) because a formant synthesizer does an imperfect job of representing the fine details of the original vowel spectrum, results using the formant-synthesized signals led to a slight overestimate of the role of duration in vowel recognition, especially for the shortened vowels. PMID:11144593

Hillenbrand, J M; Clark, M J; Houde, R A

2000-12-01

214

Electrocardiographical findings of WBN\\/Kob rats  

Microsoft Academic Search

Summary Electrocardiographical (RCG) investigations were carried out on 4 and 12 week old WBN\\/Kob and Wistar male rats. In comparison with Wistar rats which showed ECG findings typical of those of normal rats, WBN\\/Kob ratsshowed signifi- cantly larger QRS complex amplitude, smaller T wave amplitude, longer QRS duration, and longer QT interval at 4 weeks of age. This tendency became

K. MACHIDAl; K. Doi; M. Kaburaki; S. Sugano

1990-01-01

215

Cohabitation Duration and Transient Domesticity  

PubMed Central

Research finds that many impoverished urban Black adults engage in a pattern of partnering and family formation involving a succession of short cohabitations yielding children, a paradigm referred to as transient domesticity. Researchers have identified socioeconomic status, cultural adaptations, and urbanicity as explanations for aspects of this pattern. We used longitudinal data from the 2001 Survey of Income and Program Participation to analyze variation in cohabitation and marriage duration by race/ethnicity, income, and urban residence. Proportional hazards regression indicated that separation risk is greater among couples that are cohabiting, below 200% of the federal poverty line, and Black but is not greater among urban dwellers. This provides empirical demographic evidence to support the emerging theory of transient domesticity and suggests that both socioeconomic status and race explain this pattern. We discuss the implications of these findings for understanding transient domesticity and make recommendations for using the Survey of Income and Program Participation to further study this family formation paradigm.

GOLUB, ANDREW; REID, MEGAN; STRICKLER, JENNIFER; DUNLAP, ELOISE

2013-01-01

216

Intra-QRS high-frequency ECG changes with ischemia. Is it possible to evaluate these changes using the signal-averaged Holter ECG in dogs?  

PubMed

The purpose of this experiment is to study the possibility of intra-QRS high-frequency electrocardiographic (HFECG) changes for the evaluation of and recovery from myocardial ischemia in both the time-domain and spectral-turbulence analyses on the signal-averaged ECG using the Holter ECG monitoring (Holter SAECG) system. A balloon catheter was inserted into the left anterior descending coronary artery (LAD of 8 mongrel dogs and was maintained inflated for 2 hours to occlude the LAD and then was deflated to allow for reperfusion. The cardiac signal from the three orthogonal leads of the surface ECG (X, Y, and Z) was recorded and analyzed with a Del Mar Avionics (model 459, Irvine, CA) recorder and analyzer (model 563). The Holter SAECG was assessed before the LAD occlusion phase (control), during the coronary occlusion phase (ischemia), after the reperfusion phase (recovery). To evaluate intra-QRS ECG changes in the time-domain analysis, root-mean-square (RMS) voltage of the entire QRS in 40-250 HZ (40 RMS), 100-250 Hz (100 RMS), and 150-250 Hz (150 RMS) were studied and the vector magnitude of the QRS was depicted. In the spectral-turbulence analysis and spectrocardiogram to study the discordance of the ECG wave front velocity by fast Fourier transformation analysis, the interslice correlation mean (IC mean) and interslice correlation standard deviation (IC SD), which were calculated as the mean and standard deviation of the Pearson correlation coefficient of each time slice with its neighbor, were investigated. In the time-domain analysis, the LAD occlusion by balloon catheter at ischemia produced a reduction in 40 RMS, 100 RMS, and 150 RMS, while a restoration was seen at recovery in 40 RMS and 100 RMS. In the spectral-turbulence analysis, LAD occlusion at ischemia caused a decrease in IC mean and an increase in IC SD. The waveform of the vector magnitude and the spectrocardiogram seen at control showed changes with ischemia and was restored at recovery with the coronary reperfusion. It was thought possible to capture the intra-QRS HFECG changes that occur during myocardial ischemia and recovery from it in the time-domain analysis and spectral-turbulence analysis on the Holter SAECG system in spite of the limitation of this methodology. To evaluate myocardial ischemia and recovery, this method should be useful clinically. PMID:8656120

Yakubo, S; Ozawa, Y; Komaki, K

1995-01-01

217

Using Quantile Regression for Duration Analysis  

Microsoft Academic Search

Quantile regression methods are emerging as a popular technique in econometrics and biometrics for exploring the distribution of duration data. This paper discusses quantile regression for duration analysis allowing for a flexible specification of the functional relationship and of the error distribution. Censored quantile regression address the issue of right censoring of the response variable which is common in duration

Bernd Fitzenberger; Ralf A. Wilke

2005-01-01

218

Mortality and Duration of Hemodialysis Treatment  

Microsoft Academic Search

Decrease in the average duration of hemodialysis treatment time is a continuing phenomenon. We investigated the relationship of 3-year mortality to duration of dialysis in a 1984-1985 national random sample of 600 hemodialysis patients from 36 dialysis units. Mortality was negatively associated with duration of dialysis treatments, as shown by the Cox model, adjusted for other patient and dialysis unit

Philip J. Held; Nathan W. Levin; Randall R. Bovbjerg; Mark V. Pauly; Louis H. Diamond

2010-01-01

219

Sentence durations and accentedness judgments  

NASA Astrophysics Data System (ADS)

Talkers in a second language can frequently be identified as speaking with a foreign accent. It is not clear to what degree a foreign accent represents specific deviations from a target language versus more general characteristics. We examined the identifications of native and non-native talkers by listeners with various amount of knowledge of the target language. Native and non-native speakers of Latvian provided materials. All the non-native talkers spoke Russian as their first language and were long-term residents of Latvia. A listening test, containing sentences excerpted from a short recorded passage, was presented to three groups of listeners: native speakers of Latvian, Russians for whom Latvian was a second language, and Americans with no knowledge of either of the two languages. The listeners were asked to judge whether each utterance was produced by a native or non-native talker. The Latvians identified the non-native talkers very accurately, 88%. The Russians were somewhat less accurate, 83%. The American listeners were least accurate, but still identified the non-native talkers at above chance levels, 62%. Sentence durations correlated with the judgments provided by the American listeners but not with the judgments provided by native or L2 listeners.

Bond, Z. S.; Stockmal, Verna; Markus, Dace

2003-04-01

220

Extended Duration Orbiter Medical Project  

NASA Technical Reports Server (NTRS)

Biomedical issues have presented a challenge to flight physicians, scientists, and engineers ever since the advent of high-speed, high-altitude airplane flight in the 1940s. In 1958, preparations began for the first manned space flights of Project Mercury. The medical data and flight experience gained through Mercury's six flights and the Gemini, Apollo, and Skylab projects, as well as subsequent space flights, comprised the knowledge base that was used to develop and implement the Extended Duration Orbiter Medical Project (EDOMP). The EDOMP yielded substantial amounts of data in six areas of space biomedical research. In addition, a significant amount of hardware was developed and tested under the EDOMP. This hardware was designed to improve data gathering capabilities and maintain crew physical fitness, while minimizing the overall impact to the microgravity environment. The biomedical findings as well as the hardware development results realized from the EDOMP have been important to the continuing success of extended Space Shuttle flights and have formed the basis for medical studies of crew members living for three to five months aboard the Russian space station, Mir. EDOMP data and hardware are also being used in preparation for the construction and habitation of International Space Station. All data sets were grouped to be non-attributable to individuals, and submitted to NASA s Life Sciences Data Archive.

Sawin, Charles F. (Editor); Taylor, Gerald R. (Editor); Smith, Wanda L. (Editor); Brown, J. Travis (Technical Monitor)

1999-01-01

221

Icing Encounter Duration Sensitivity Study  

NASA Technical Reports Server (NTRS)

This paper describes a study performed to investigate how aerodynamic performance degradation progresses with time throughout an exposure to icing conditions. It is one of the first documented studies of the effects of ice contamination on aerodynamic performance at various points in time throughout an icing encounter. Both a 1.5 and 6 ft chord, two-dimensional, NACA-23012 airfoils were subjected to icing conditions in the NASA Icing Research Tunnel for varying lengths of time. At the end of each run, lift, drag, and pitching moment measurements were made. Measurements with the 1.5 ft chord model showed that maximum lift and pitching moment degraded more rapidly early in the exposure and degraded more slowly as time progressed. Drag for the 1.5 ft chord model degraded more linearly with time, although drag for very short exposure durations was slightly higher than expected. Only drag measurements were made with the 6 ft chord airfoil. Here, drag for the long exposures was higher than expected. Novel comparison of drag measurements versus an icing scaling parameter, accumulation parameter times collection efficiency was used to compare the data from the two different size model. The comparisons provided a means of assessing the level of fidelity needed for accurate icing simulation.

Addy, Harold E., Jr.; Lee, Sam

2011-01-01

222

Differences in QRS configuration during unipolar pacing from adjacent sites: implications for the spatial resolution of pace-mapping.  

PubMed

To examine the spatial resolution of unipolar pace-mapping, 12 lead electrocardiograms (ECGs) recorded during pacing from each of the poles of a quadripolar catheter (5 mm interelectrode distance) were examined. Unipolar pacing was performed from each of the poles at late diastolic threshold, twice threshold and 10 mA at a cycle length of 500 ms. In 15 patients, pacing was performed at the right ventricular apex and in 14 at various left ventricular sites. Pacing from the distal catheter pole at threshold (index ECG) was used to simulate the site of origin of ventricular tachycardia, and all other ECGs were compared with the index ECG. Electrocardiograms were evaluated by two independent observers for 1) minor configuration differences (notch, new small component, change in the amplitude of individual components or change in QRS shape); 2) major differences in configuration (new large component, marked change in the amplitude of an existing component or two minor changes); and 3) peak to peak changes in amplitude. Minor differences in configuration were seen in a mean 2.4 +/- 1.9, 4.6 +/- 2.4 and 4.4 +/- 2.9 leads during pacing at 5, 10 and 15 mm from the distal electrode (index site). Major differences in configuration were seen in a mean of 0.3 +/- 0.5, 2.1 +/- 2.1 and 3.7 +/- 2.3 leads during pacing at 5, 10 and 15 mm from the index site. Differences in amplitude were seen in a mean of 3.1 +/- 2.2, 5.6 +/- 2.5 and 6.8 +/- 3.0 leads per ECG during pacing at 5, 10 and 15 mm from the index ECG pacing site, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1987218

Kadish, A H; Childs, K; Schmaltz, S; Morady, F

1991-01-01

223

Ablation of Premature Ventricular Complexes Triggering Ventricular Fibrillation in a Patient with Long QT Syndrome  

PubMed Central

We describe the case of a patient with long QT syndrome and recurrent ventricular fibrillation, triggered by premature ventricular complexes (PVCs) with a left bundle branch block pattern and inferior axis of the QRS. Activation mapping demonstrated the origin of the PVCs to be in the right ventricular outflow tract. Ventricular fibrillation (VF) was successfully treated by catheter ablation of the triggering PVCs and there has been no recurrence of VF during a follow-up period of 14 months.

Sanchez-Munoz, Juan Jose; Garcuia-Alberola, Arcadi; Martinez-Sanchez, Juan; Garcia-Molina, Esperanza; Valdes-Chavarri, Mariano

2011-01-01

224

Trends in electric utility load duration curves  

SciTech Connect

This report documents the development and analysis of annual and quarterly load duration curves for each of the 10 Federal regions. The report describes analyses performed to test for changes in load duration curve shapes over time. These analyses are intended to aid the electric utility analyses and modeling activities of the Energy Information Administration (EIA) by expanding the understanding of current and expected load duration curve shapes. 7 figs., 13 tabs.

Not Available

1984-12-01

225

Using quantile regression for duration analysis  

Microsoft Academic Search

Summary  Quantile regression methods are emerging as a popular technique in econometrics and biometrics for exploring the distribution\\u000a of duration data. This paper discusses quantile regression for duration analysis allowing for a flexible specification of\\u000a the functional relationship and of the error distribution. Censored quantile regression addresses the issue of right censoring\\u000a of the response variable which is common in duration

Bernd Fitzenberger; Ralf A. Wilke

2006-01-01

226

Training for long duration space missions  

NASA Technical Reports Server (NTRS)

The successful completion of an extended duration manned mission to Mars will require renewed research effort in the areas of crew training and skill retention techniques. The current estimate of inflight transit time is about nine months each way, with a six month surface visit, an order of magnitude beyond previous U.S. space missions. Concerns arise when considering the level of skill retention required for highly critical, one time operations such as an emergency procedure or a Mars orbit injection. The factors responsible for the level of complex skill retention are reviewed, optimal ways of refreshing degraded skills are suggested, and a conceptual crew training design for a Mars mission is outlined. Currently proposed crew activities during a Mars mission were reviewed to identify the spectrum of skills which must be retained over a long time period. Skill retention literature was reviewed to identify those factors which must be considered in deciding when and which tasks need retraining. Task, training, and retention interval factors were identified. These factors were then interpreted in light of the current state of spaceflight and adaptive training systems.

Goldberg, Joseph H.

1987-01-01

227

Sleep duration and personality in Croatian twins.  

PubMed

The objective of this study was to examine which genetic and environmental influences contribute to individual differences in sleep duration in a sample of Croatian adolescent/early adult twins, as well as to investigate the relationship between personality and sleep duration. Participants included 339 twin pairs (105 monozygotic and 234 dizygotic) aged between 15 and 22 years. They reported on their average sleep duration and personality. The broad heritability estimate (additive and non-additive genetic influences) for sleep duration was 0.63, while personality estimates ranged between 0.47 and 0.62. Significant negative phenotypic associations with neuroticism and openness were mainly genetically mediated 100 and 80%, respectively. Only 6% of the sleep duration variance was explained by genetic influences shared with neuroticism and openness. In regression analysis, age, gender and five personality traits explained 5% of sleep duration variance, with neuroticism and openness as significant predictors. Comparison of short, moderate and long sleepers showed that participants in the short sleepers group had significantly higher neuroticism scores than groups of moderate and long sleepers, as well as a significantly higher openness score than the group of long sleepers. This indicates that personality traits of neuroticism and openness contribute to the prediction of sleep duration due to overlapping genetic influences that contribute to both these personality traits and sleep duration. However, as phenotypic overlap of personality and sleep duration is relatively weak, heritability of sleep duration is not only related to individual differences in personality traits, so future research needs to examine other phenotypic correlates of sleep duration. PMID:24635510

Butkovic, Ana; Vukasovic, Tena; Bratko, Denis

2014-04-01

228

COMPLEX TRAUMA, COMPLEX REACTIONS: ASSESSMENT AND TREATMENT  

Microsoft Academic Search

Complex trauma occurs repeatedly and escalates over its duration. In families, it is exemplified by domestic violence and child abuse and in other situations by war, prisoner of war or refugee status, and human trafficking. Complex trauma also refers to situations such as acute\\/chronic illness that requires intensive medical intervention or a single traumatic event that is calamitous. Complex trauma

Christine A. Courtois

2004-01-01

229

On the Duration of Civil War  

Microsoft Academic Search

The duration of large-scale, violent civil conflict increases substantially if the society is composed of a few large ethnic groups, if there is extensive forest cover, and if the conflict has commenced since 1980. None of these factors affects the initiation of conflict. And neither the duration nor the initiation of conflict is affected by initial inequality or political repression.Collier,

Paul Collier; Anke Hoeffler

2001-01-01

230

Stimulus Intensity and the Perception of Duration  

ERIC Educational Resources Information Center

This article explores the widely reported finding that the subjective duration of a stimulus is positively related to its magnitude. In Experiments 1 and 2 we show that, for both auditory and visual stimuli, the effect of stimulus magnitude on the perception of duration depends upon the background: Against a high intensity background, weak stimuli…

Matthews, William J.; Stewart, Neil; Wearden, John H.

2011-01-01

231

Mortality Associated With Sleep Duration and Insomnia  

Microsoft Academic Search

Background: Patients often complain about insuffi- cient sleep or chronic insomnia in the belief that they need 8 hours of sleep. Treatment strategies may be guided by what sleep durations predict optimal survival and whether insomnia might signal mortality risks. Methods: In 1982, the Cancer Prevention Study II of the American Cancer Society asked participants about their sleep duration and

Daniel F. Kripke; Lawrence Garfinkel; Deborah L. Wingard; Melville R. Klauber; Matthew R. Marler

2002-01-01

232

Duration of cannabis use — a novel phenotype?  

Microsoft Academic Search

Although cannabis is the most commonly used illicit drug, duration of cannabis use is typically short, with many of those who initiate cannabis use ceasing use by their late twenties. In this paper we analyze data from a volunteer Australian cohort of 6265 male and female twins to examine whether the duration of cannabis use is an informative phenotype for

Michael T. Lynskey; Julia D. Grant; Elliot C. Nelson; Kathleen K. Bucholz; Pamela A. F. Madden; Dixie J. Statham; Nicholas G. Martin; Andrew C. Heath

2006-01-01

233

Determinants of unemployment duration in Ukraine  

Microsoft Academic Search

There are few studies of unemployment duration in transition economies, including members of the CIS. This paper presents the first evidence of the determinants of unemployment duration in Ukraine. We examine the effects of various individual characteristics and local demand conditions on the hazards to employment or inactivity using multiple unemployment spell data from the Ukrainian Longitudinal Monitoring Survey (ULMS)

Olga Kupets

2006-01-01

234

Does aftershock duration scale with mainshock size?  

Microsoft Academic Search

It has been claimed that aftershock duration scales with the mainshock recurrence interval [Dieterich, 1994]. This implies a scaling between aftershock duration and mainshock magnitude. To see if such a scaling exist, we compare properties of aftershock sequences associated with mainshocks whose size span several magnitude units. Earthquake properties were examined along two northern California fault segments, one is the

A. Ziv

2006-01-01

235

Repetition duration influences ratings of perceived exertion.  

PubMed

This study investigated the effect of different repetition durations on ratings of perceived exertion (RPE) in active muscles (RPE-AM) and the overall body (RPE-O). 19 male volunteers (M age = 25.4 yr., SD = 3.5) performed strength training protocols with multiple sets matched by the number of sets and repetitions, intensity and rest interval but different repetition durations: 4 sec., 6 sec., or self-paced. Participants were asked to estimate their RPE-AM and RPE-O after each set. Training protocols with a 6-sec. repetition duration produced distinct responses on RPE during and after performance compared to 4-sec. and self-paced durations. However, there were no significant differences between 4-sec. and self-paced durations. PMID:24724526

Diniz, Rodrigo C R; Martins-Costa, Hugo C; Machado, Sandra C; Lima, Fernando V; Chagas, Mauro H

2014-02-01

236

Thermoresponsive nanogels for prolonged duration local anesthesia  

PubMed Central

Nanogels based on poly(N-isopropylacrylamide) are attractive vehicles for prolonged duration local anesthesia because of their tunable size, number of functional groups, thermoresponsiveness, and their anionic charge. Nerve block durations of up to nine hours were achieved using acrylic acid-loaded nanogels loaded with bupivacaine. Increasing the anionic charge density of the nanogels or (for more highly acid-functionalized nanogels) decreasing the nanogel size facilitated longer duration anesthetic release. Small (<300 nm diameter) nanogels formed dense aggregates upon injection in vivo and induced only mild inflammatory responses, while large (>500 nm diameter) nanogels typically remained as liquid-like residues in vivo and induced more severe inflammatory reactions.

Hoare, Todd; Young, Stuart; Lawlor, Michael W.; Kohane, Daniel S.

2012-01-01

237

Short Duration Base Heating Test Improvements.  

National Technical Information Service (NTIS)

Significant improvements have been made to a short duration space launch vehicle base heating test technique. This technique was first developed during the 1960's to investigate launch vehicle plume induced convective environments. Recent improvements inc...

R. L. Bender M. G. Dagostino B. A. Engel C. D. Engel

1999-01-01

238

Duration discrimination in the mouse ( Mus musculus )  

Microsoft Academic Search

Detection thresholds for an increment in duration of a 10-kHz pure tone were determined in the NMRI mouse using a Go\\/NoGo-procedure and the method of constant stimuli. Thresholds for reference durations of 50, 100 and 200 ms were obtained presenting the signals at a fixed level or at a level varying by ±3 dB. Thresholds were determined using signal-detection theory ( d?=1.0

Karin B. Klink; Georg M. Klump

2004-01-01

239

Ischemic Ventricular Tachycardia Presenting as a Narrow Complex Tachycardia  

PubMed Central

This report describes a patient presenting with a narrow complex tachycardia in the context of prior myocardial infarction and impaired ventricular function. Electrophysiological studies confirmed ventricular tachycardia and activation and entrainment mapping demonstrated a critical isthmus within an area of scar involving the His-Purkinje system accounting for the narrow QRS morphology. This very rare case shares some similarities with upper septal ventricular tachycardia seen in patients with structurally normal hearts, but to our knowledge has not been seen previously in patients with ischemic heart disease.

Page, Stephen P; Watts, Troy; Yeo, Wee Tiong; Mehul, Dhinoja

2014-01-01

240

Microcontroller uses in Long-Duration Ballooning  

NASA Astrophysics Data System (ADS)

This paper discusses how microcontrollers are being utilized to fulfill the demands of long duration ballooning (LDB) and the advantages of doing so. The Columbia Scientific Balloon Facility (CSBF) offers the service of launching high altitude balloons (120k ft) which provide an over the horizon telemetry system and platform for scientific research payloads to collect data. CSBF has utilized microcontrollers to address multiple tasks and functions which were previously performed by more complex systems. A microcontroller system has been recently developed and programmed in house to replace our previous backup navigation system which is used on all LDB flights. A similar microcontroller system was developed to be independently launched in Antarctica before the actual scientific payload. This system's function is to transmit its GPS position and a small housekeeping packet so that we can confirm the upper level float winds are as predicted from satellite derived models. Microcontrollers have also been used to create test equipment to functionally check out the flight hardware used in our telemetry systems. One test system which was developed can be used to quickly determine if our communication link we are providing for the science payloads is functioning properly. Another system was developed to provide us with the ability to easily determine the status of one of our over the horizon communication links through a closed loop system. This test system has given us the capability to provide more field support to science groups than we were able to in years past. The trend of utilizing microcontrollers has taken place for a number of reasons. By using microcontrollers to fill these needs, it has given us the ability to quickly design and implement systems which meet flight critical needs, as well as perform many of the everyday tasks in LDB. This route has also allowed us to reduce the amount of time required for personnel to perform a number of the tasks required during the initial fabrication and also refurbishing processes of flight hardware systems. The recent use of microcontrollers in the design of both LDB flight hardware and test equipment has shown some examples of the adaptability and usefulness they have provided for our workplace.

Jones, Joseph

241

Sleep duration, cardiovascular disease, and proinflammatory biomarkers  

PubMed Central

Habitual sleep duration has been associated with cardiometabolic disease, via several mechanistic pathways, but few have been thoroughly explored. One hypothesis is that short and/or long sleep duration is associated with a proinflammatory state, which could increase risk for cardiovascular and metabolic diseases. This hypothesis has been largely explored in the context of experimental sleep deprivation studies which have attempted to demonstrate changes in proinflammatory markers following acute sleep loss in the laboratory. Despite the controlled environment available in these studies, samples tend to lack generalization to the population at large and acute sleep deprivation may not be a perfect analog for short sleep. To address these limitations, population based studies have explored associations between proinflammatory markers and habitual sleep duration. This review summarizes what is known from experimental and cross-sectional studies about the association between sleep duration, cardiovascular disease, and proinflammatory biomarkers. First, the association between sleep duration with both morbidity and mortality, with a focus on cardiovascular disease, is reviewed. Then, a brief review of the potential role of proinflammatory markers in cardiovascular disease is presented. The majority of this review details specific findings related to specific molecules, including tumor necrosis factor-?, interleukins-1, -6, and -17, C-reactive protein, coagulation molecules, cellular adhesion molecules, and visfatin. Finally, a discussion of the limitations of current studies and future directions is provided.

Grandner, Michael A; Sands-Lincoln, Megan R; Pak, Victoria M; Garland, Sheila N

2013-01-01

242

Ongoing behavior predicts perceptual report of interval duration.  

PubMed

The ability to estimate the passage of time is essential for adaptive behavior in complex environments. Yet, it is not known how the brain encodes time over the durations necessary to explain animal behavior. Under temporally structured reinforcement schedules, animals tend to develop temporally structured behavior, and interval timing has been suggested to be accomplished by learning sequences of behavioral states. If this is true, trial to trial fluctuations in behavioral sequences should be predictive of fluctuations in time estimation. We trained rodents in an duration categorization task while continuously monitoring their behavior with a high speed camera. Animals developed highly reproducible behavioral sequences during the interval being timed. Moreover, those sequences were often predictive of perceptual report from early in the trial, providing support to the idea that animals may use learned behavioral patterns to estimate the duration of time intervals. To better resolve the issue, we propose that continuous and simultaneous behavioral and neural monitoring will enable identification of neural activity related to time perception that is not explained by ongoing behavior. PMID:24672473

Gouvęa, Thiago S; Monteiro, Tiago; Soares, Sofia; Atallah, Bassam V; Paton, Joseph J

2014-01-01

243

Stimulus intensity and the perception of duration.  

PubMed

This article explores the widely reported finding that the subjective duration of a stimulus is positively related to its magnitude. In Experiments 1 and 2 we show that, for both auditory and visual stimuli, the effect of stimulus magnitude on the perception of duration depends upon the background: Against a high intensity background, weak stimuli are judged to last longer. In Experiment 3 we show that the effect of intensity becomes more pronounced at longer durations, consistent with the idea that stimulus intensity affects the pacemaker component of an internal clock, and that it is the difference of a stimulus from the background, rather than its absolute magnitude, which influences the rate of the pacemaker. These results urge a modification to the oft-repeated claim that more intense stimuli seem to last longer, and provide an important constraint on any model of human timing. PMID:20731508

Matthews, William J; Stewart, Neil; Wearden, John H

2011-02-01

244

Perceived duration decreases with increasing eccentricity.  

PubMed

Previous studies examining the influence of stimulus location on temporal perception yield inhomogeneous and contradicting results. Therefore, the aim of the present study is to soundly examine the effect of stimulus eccentricity. In a series of five experiments, subjects compared the duration of foveal disks to disks presented at different retinal eccentricities on the horizontal meridian. The results show that the perceived duration of a visual stimulus declines with increasing eccentricity. The effect was replicated with various stimulus orders (Experiments 1-3), as well as with cortically magnified stimuli (Experiments 4-5), ruling out that the effect was merely caused by different cortical representation sizes. The apparent decreasing duration of stimuli with increasing eccentricity is discussed with respect to current models of time perception, the possible influence of visual attention and respective underlying physiological characteristics of the visual system. PMID:24880978

Kliegl, Katrin M; Huckauf, Anke

2014-07-01

245

STS mission duration enhancement study: (orbiter habitability)  

NASA Technical Reports Server (NTRS)

Habitability improvements for early flights that could be implemented with minimum impact were investigated. These included: (1) launching the water dispenser in the on-orbit position instead of in a locker; (2) the sleep pallet concept; and (3) suction cup foot restraints. Past studies that used volumetric terms and requirements for crew size versus mission duration were reviewed and common definitions of key habitability terms were established. An accurately dimensioned drawing of the orbiter mid-deck, locating all of the known major elements was developed. Finally, it was established that orbiter duration and crew size can be increased with minimum modification and impact to the crew module. Preliminary concepts of the aft med-deck, external versions of expanded tunnel adapters (ETA), and interior concepts of ETA-3 were developed and comparison charts showing the various factors of volume, weight, duration, size, impact to orbiter, and number of sleep stations were generated.

Carlson, A. D.

1979-01-01

246

Chronotype and sleep duration: The influence of season of assessment.  

PubMed

Little is known about human entrainment under natural conditions, partly due to the complexity of human behavior, torn between biological and social time and influenced by zeitgebers (light-dark cycles) that are progressively "polluted" (and thereby weakened) by artificial light. In addition, data about seasonal variations in sleep parameters are scarce. We, therefore, investigated seasonal variation in cross-sectional assessments of sleep/wake times of 9765 subjects from four European populations (EGCUT?=?Estonian Genome Centre, University of Tartu in Estonia; KORA?=?Cooperative Health Research in the Region of Augsburg in Germany; KORCULA?=?The Korcula study in Croatia; and ORCADES?=?The Orkney Complex Disease Study in Scotland). We identified time-of-year dependencies for the distribution of chronotype (phase of entrainment assessed as the mid-sleep time point on free days adjusted for sleep deficit of workdays) in cohorts from Estonia (EGCUT) and Germany (KORA). Our results indicate that season (defined as daylight saving time - DST and standard zonetime periods - SZT) specifications of photoperiod influence the distribution of chronotype (adjusted for age and sex). Second, in the largest investigated sample, from Estonia (EGCUT; N?=?5878), we could detect that seasonal variation in weekly average sleep duration was dependent on individual chronotype. Later chronotypes in this cohort showed significant variation in their average sleep duration across the year, especially during DST (1?h advance in social time from the end of March to end of October), while earlier chronotypes did not. Later chronotypes not only slept less during the DST period but the average chronotype of the population assessed during this period was earlier than during the SZT (local time for a respective time zone) period. More in detail, hierarchical multiple regression analyses showed that, beyond season of assessment (DST or SZT), social jetlag (SJl; the discrepancy between the mid sleep on free and work days - which varied with age and sex) contributed to a greater extent to the variation in sleep duration than chronotype (after taking into account factors that are known to influence sleep duration, i.e. age, sex and body mass index). Variation in chronotype was also dependent on age, sex, season of assessment and SJl (which is highly correlated with chronotype - SJl was larger among later chronotypes). In summary, subjective assessments of sleep/wake times are very reliable to assess internal time and sleep duration (e.g. reproducing sleep duration and timing tendencies related to age and sex across the investigated populations), but season of assessment should be regarded as a potential confounder. We identified in this study photoperiod (seasonal adaptation) and SJl as two main factors influencing seasonal variation in chronotype and sleep duration. In conclusion, season of assessment, sex and age have an effect on epidemiological variation in sleep duration, chronotype and SJl, and should be included in studies investigating associations between these phenotypes and health parameters, and on the development of optimal prevention strategies. PMID:24679223

Allebrandt, Karla V; Teder-Laving, Maris; Kantermann, Thomas; Peters, Annette; Campbell, Harry; Rudan, Igor; Wilson, James F; Metspalu, Andres; Roenneberg, Till

2014-06-01

247

Slow Wave Sleep and Long Duration Spaceflight  

NASA Technical Reports Server (NTRS)

To review the literature on slow wave sleep (SWS) in long duration space flight, and place this within the context of the broader literature on SWS particularly with respect to analogous environments such as the Antarctic. Explore how SWS could be measured within the International Space Station (ISS) context with the aim to utilize the ISS as an analog for future extra-orbital long duration missions. Discuss the potential use of emergent minimally intrusive wireless technologies like ZEO for integrated prelaunch, flight, and return to Earth analysis and optimization of SWS (and general quality of sleep).

Orr, M.; Whitmire, A.; Arias, D.; Leveton, L.

2011-01-01

248

Duration of the earth-formation interval  

NASA Astrophysics Data System (ADS)

The duration of the formation interval of prototerrestrial matter is estimated on the basis of the iodine-xenon and plutonium-xenon dating techniques. The formation interval is shown to include two phases: (1) a galactic (nebular) phase corresponding to the independent existence of two sources and lasting 150 million years; and (2) a planetesimal (accretion) phase lasting not more than 140 million years. The total duration of the formation interval from the termination of nucleosynthesis to the formation of the planet amounts to not more than 300-400 million years.

Levskii, L. K.

249

Effect of Second-Phase Duration on the Strength-Duration Relation for Human Transvenous Defibrillation  

Microsoft Academic Search

Background—The mechanism by which biphasic waveforms improve defibrillation efficacy is unclear. In addition, the optimal shape of the biphasic waveforms remains controversial. Animal experiments suggest that prolonging the duration of the second phase longer than the first worsens defibrillation thresholds (DFT). The purpose of this study was to determine the strength-duration relation for the second phase of a biphasic defibrillation

Stephen R. Shorofsky; Michael R. Gold

250

Duration of Incubation of Fungal Cultures  

Microsoft Academic Search

To determine the optimum duration of incubation for recovery of fungi, the results of 2,173 consecutive clinical cultures were reviewed. Overall, 94% of fungal isolates were detected by day 7 and 98% were detected by day 14. Yeasts were usually (98%) detected within thefirst week of incubation. Recovery of molds required more time, but 81% were detected by day 7

ARTHUR J. MORRIS; TERRY C. BYRNE; JOHN F. MADDEN; BARTH RELLER

1996-01-01

251

LONG DURATION EXPOSURE FACILITY (LDEF) ARCHIVE SYSTEM  

Microsoft Academic Search

SUMMARY The Long Duration Exposure Facility (LDEF) Archive System is designed to provide spacecraft designers and space environment researchers single point access to all available resources from LDEF. These include data, micrographs, photographs, technical reports, papers, hardware and test specimens, as well as technical expertise. Further, the LDEF Archive System is planned such that it could be the foundation for

Brenda K. Wilson

252

Duration of antiviral immunity after smallpox vaccination  

Microsoft Academic Search

Although naturally occurring smallpox was eliminated through the efforts of the World Health Organization Global Eradication Program, it remains possible that smallpox could be intentionally released. Here we examine the magnitude and duration of antiviral immunity induced by one or more smallpox vaccinations. We found that more than 90% of volunteers vaccinated 25–75 years ago still maintain substantial humoral or

Erika Hammarlund; Matthew W Lewis; Scott G Hansen; Lisa I Strelow; Jay A Nelson; Gary J Sexton; Jon M Hanifin; Mark K Slifka

2003-01-01

253

Sleep Duration and Breast Cancer Phenotype  

PubMed Central

Emerging evidence suggests that short sleep is associated with an increased risk of cancer; however, little has been done to study the role of sleep on tumor characteristics. In this study, we evaluated the relationship between sleep duration and tumor phenotype in 972 breast cancer patients. Sleep duration was inversely associated with tumor grade (univariate P = 0.032), particularly in postmenopausal women (univariate P = 0.018). This association did not reach statistical significance after adjustments for age, race, body mass index, hormone replacement therapy use, alcohol consumption, smoking, and physical activity in the entire study sample (P = 0.052), but it remained statistically significant (P = 0.049) among post-menopausal patients. We did not observe a statistically significant association between sleep duration and stage at diagnosis, ER, or HER2 receptor status. These results present a modest association between short duration of sleep and higher grade breast cancer in post-menopausal women. Further work needs to be done to validate these findings.

Khawaja, Ali; Rao, Santosh; Li, Li; Thompson, Cheryl L.

2013-01-01

254

Small, Short Duration Technical Team Dynamics.  

National Technical Information Service (NTIS)

How to build effective teams is one of the most significant management questions of the day. Small, short duration technical teams drive critically important decision-making processes in a broad range of organizations in all sectors of the economy. Thus, ...

P. J. Knight

2006-01-01

255

Perception of duration in the parvocellular system.  

PubMed

Both theoretical and experimental evidence suggests that duration perception is mediated preferentially by the color-blind but high temporally sensitive luminance pathway. In this experiment we tested whether color modulated stimuli and high spatial frequency luminance modulated stimuli, which are known to be relayed mostly by the slow parvocellular system, are able to elicit reliable sense of duration. We show that ramped color modulated stimuli seem to last less than luminance modulated stimuli matched for visibility. The effect is large, about 200 ms and is constant at all durations tested (range 500-1100 ms). However, high spatial frequency luminance stimuli obtain duration matches similar to those of low spatial frequency luminance modulated stimuli. The results at various levels of contrast and temporal smoothing indicate that equiluminant stimuli have higher contrast thresholds to activate the mechanisms which time visual stimuli. Overall the results imply that both the magnocellular and the parvocellular systems access reliably the timing mechanisms with a difference only in the way these are engaged. PMID:22470323

Cicchini, Guido M

2012-01-01

256

long duration dust storm sequences on Mars  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor (MGS) Mars Observer Camera (MOC) and Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI) Mars daily global maps have revealed new characteristics for long duration dust storm sequences. These dust storm sequences have long histories of more than a week, travel long distances out of their origination region, and influence large areas in different regions of the planet. During the Ls = 180 - 360 season, except for global dust storms which involve multiple remote dust lifting centers and generally expand explosively from the southern hemisphere northward, other long-lived dust storm sequences usually travel southward through the Acidalia-Chryse, Utopia-Isidis or Arcadia-Amazonis channels with subsequent dust lifting along the way. Sometimes, they penetrate remarkably deep to the southern high latitudes, producing fantastic display of dust band. During the rest of the year, long duration dust storm sequences usually originate from the Argyre/Solis, Hellas/Noachis, or Cimmeria/Sirenum area and travel northward toward the southern low latitudes. Each route exhibits its own peculiar characteristics. We will present our results about these long duration dust storm sequences summarized from the complete archive of MGS MOC daily global maps and two years of MRO MARCI daily global maps. The systematic daily nearly global coverage of these maps makes it feasible to reconstruct the history of long duration dust storm sequences with detail.

Wang, H.

2012-12-01

257

Haloperidol affects guinea pig chewing burst durations.  

PubMed

Previous investigations have reported that most movement patterns in humans and other mammalian species are partitioned into 1-5-s units. This finding has led to the hypothesis that a highly conservative physiological system, common among mammalian species, segments ongoing movement patterns into 1-5-s 'chunks'. However, to date little or no work has been done to explore the physiological and neurochemical nature of this segmenting phenomenon; therefore, it is unknown whether the same evolutionarily conservative mechanism controls partitioning of all movement patterns. The literature suggests that central dopamine plays a key role in this 1-5-s partitioning. If this is so, then dopamine blockers should result in significant alterations in the 1-5-s segmentation of mammalian movement patterns. To test this hypothesis, the current study determined whether the neuroleptic haloperidol significantly affected guinea pig chewing burst durations, which reportedly average 1-3 s and are therefore considered to manifest this partitioning phenomenon. Seven male albino guinea pigs received daily 0.5 mg/kg i.m. haloperidol injections, and three male albino guinea pigs received comparable saline injections (controls). After either 3 or 11 weeks, injections were stopped, and 1 week thereafter the animals were starved for 24 h and then videotaped singly in an experimental arena. Animals inevitably fed on alfalfa pellets during the taping session, and the chewing bursts that occurred while the animals fed were timed. The results showed that control animals' chewing bursts had durations similar to those previously reported for free-roaming, non-drug-treated guinea pigs. However, haloperidol-treated guinea pigs' chewing bursts were significantly more variable in duration (p = 0.0013) than those of matched control animals. Inspection of the data from individual animals revealed that two haloperidol-treated animals had abnormally short chewing burst durations, whereas three haloperidol-treated animals had abnormally long chewing burst durations. The fact that haloperidol treatment was associated with either abnormally short or long chewing burst durations is reminiscent of neuroleptic-induced human movement disorders, which reportedly range from a 'paucity of movement' to 'perseverant movements'. This suggests that intact central dopaminergic systems may play an important role in modulating the duration of mammalian movement patterns, which normally ranges 0.2-5 s. PMID:8853875

Gerstner, G E

1996-01-01

258

The employment service and vacancy durations.  

PubMed

In the literature, there are few examples of studies analyzing the impact of labor market programs on vacancies. This article presents the results of a study of the impact of personnel increase at Swedish employment offices on vacancy durations. The evaluation method in the study is quasi-experimental. The main results of the study are as follows: (a) The increase of employment office staff members reduced their vacancy durations by approximately 2 days, and the probability that a vacancy is cancelled from the register is 1.17 times higher for the program offices; and (b) this effect is too small for the increase of staff members to represent a socially efficient use of resources and for a positive outcome in a public finance context. PMID:12465572

Behrenz, Lars

2002-12-01

259

Extended duration Orbiter life support definition  

NASA Technical Reports Server (NTRS)

Extending the baseline seven-day Orbiter mission to 30 days or longer and operating with a solar power module as the primary source for electrical power requires changes to the existing environmental control and life support (ECLS) system. The existing ECLS system imposes penalties on longer missions which limit the Orbiter capabilities and changes are required to enhance overall mission objectives. Some of these penalties are: large quantities of expendables, the need to dump or store large quantities of waste material, the need to schedule fuel cell operation, and a high landing weight penalty. This paper presents the study ground rules and examines the limitations of the present ECLS system against Extended Duration Orbiter mission requirements. Alternate methods of accomplishing ECLS functions for the Extended Duration Orbiter are discussed. The overall impact of integrating these options into the Orbiter are evaluated and significant Orbiter weight and volume savings with the recommended approaches are described.

Kleiner, G. N.; Thompson, C. D.

1978-01-01

260

Long Duration Incoherent Scatter Data Sets  

NASA Astrophysics Data System (ADS)

Recent developments in Incoherent Scatter radar hardware, coding techniques, data processing and data distribution make the recording of extended datasets both practical and valuable. The EISCAT Svalbard Radar has been developing the infrastructure to support long experiments and can already handle programmes with durations of two to four weeks (or more). Long duration experiments provide possibilities to study phenomena not normally accessible to these facilities and also provide datasets applicable to comparison with many ionospheric and atmospheric models. The ready availability of fully analysed data through WWW-based database tools allows these data to be easily exploited by a wide user community. Using examples from recent operations, this paper investigates some of the potential of these new capabilities and shows how users can easily exploit the data as a resource for their own research.

van Eyken, A.

2002-12-01

261

Extended Duration Orbiter - Meeting the challenge  

NASA Technical Reports Server (NTRS)

The paper overviews the Extended Duration Orbiter (EDO) program designed to provide an on-orbit stay capability of 16 days using the Orbiter Vehicle OV-102. Special attention is given to the EDO's subsystems and substructures, including the cryogenic pallet, the cryogenic storage tanks, the cryogenic solenoid valves, the regenerable carbon dioxide removal system, and the waste collection system. The EDO program will start with the STS-50 U.S. Microgravity Lab mission planned for June 1992.

Saucier, D. R.

1992-01-01

262

Sleep Duration and Circulating Adipokine Levels  

PubMed Central

Introduction: Short sleep duration is associated with systemic inflammation and diabetes; however the mechanisms by which reduced sleep leads to these complications are unclear. One possibility is sleep may impact secretion of adipocyte derived hormones that regulate inflammation and insulin resistance. In this study we assessed the association between sleep duration and 3 adipokine levels. Methods: A total of 561 adults from the Cleveland Family Study underwent standardized laboratory polysomnography followed by a morning fasting blood draw assayed for leptin, visfatin, and retinol binding protein-4 (RBP4) levels. Results: The cohort had an age of 44.5 (16.1) years and total sleep time (TST) of 6.2 (1.3) hours (mean [SD]). Each hour reduction in TST was associated with a 10% increase in leptin (P = 0.01) and a 14% increase in visfatin levels (P = 0.03) in analyses adjusted for age, gender, and race. After additional adjustment for obesity, sleep apnea severity, hypertension, and diabetes, each hour reduction in TST was associated with a 6% increase in leptin (P = 0.01) and a 14% increase in visfatin levels (P = 0.02). Leptin increased by 15% (P = 0.01) and visfatin increased by 31% (P = 0.05) for every 1-h decrease in REM sleep. In contrast, no association between sleep duration and RBP4 was found. Conclusions: Reduced sleep and reduced REM sleep are associated with elevations in leptin and visfatin, 2 adipokines associated with inflammation and insulin resistance. Further investigation of the effect of sleep on adipose tissue function should be pursued. Citation: Hayes AL; Xu F; Babineau D; Patel SR. Sleep duration and circulating adipokine levels. SLEEP 2011;34(2):147–152.

Hayes, Amanda L.; Xu, Fang; Babineau, Denise; Patel, Sanjay R.

2011-01-01

263

Evaluation of Long Duration Flight on Venus  

NASA Technical Reports Server (NTRS)

An analysis was performed to evaluate the potential of utilizing either an airship or aircraft as a flight platform for long duration flight within the atmosphere of Venus. In order to achieve long-duration flight, the power system for the vehicle had to be capable of operating for extended periods of time. To accomplish these, two types of power systems were considered, a solar energy-based power system utilizing a photovoltaic array as the main power source and a radioisotope heat source power system utilizing a Stirling engine as the heat conversion device. Both types of vehicles and power systems were analyzed to determine their flight altitude range. This analysis was performed for a station-keeping mission where the vehicle had to maintain a flight over a location on the ground. This requires the vehicle to be capable of flying faster than the wind speed at a particular altitude. An analysis was also performed to evaluate the altitude range and maximum duration for a vehicle that was not required to maintain station over a specified location. The results of the analysis show that each type of flight vehicle and power system was capable of flight within certain portions of Venus s atmosphere. The aircraft, both solar and radioisotope power proved to be the most versatile and provided the greatest range of coverage both for station-keeping and non-station-keeping missions.

Landis, Geoffrey A.; Colozza, Anthony J.

2006-01-01

264

ON THE DURATION OF BLAZAR SYNCHROTRON FLARES  

SciTech Connect

A semi-analytical model is presented that describes the temporal development of a blazar synchrotron flare for the case of a broadband synchrotron power spectrum. We examine three different injection scenarios and present its influence on the synchrotron flare. An accurate approximation of the half-life of a synchrotron flare is analytically computed and we give some illustrative examples of the time evolution of the emergent synchrotron intensity by using a numerical integration method. The synchrotron flare starts at all photon energies right after the injection of ultrarelativistic electrons into the spherical emission volume of radius R and its duration exceeds the light travel time 2R/c in the low energy regime. Furthermore, the flare duration extends by the period of injection of relativistic electrons into the emission knot. However, the energetic and spatial distribution of these injected electrons has no significant influence on the flare duration. We obtain a temporal behavior that agrees most favorably with the observations of PKS 2155-304 on 2006 July 29-30 and it differs considerably from the results that were recently achieved by using a monochromatic approximation of the synchrotron power.

Eichmann, B.; Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, 44780 Bochum (Germany); Rhode, W. [Experimentelle Physik V, Technische Universitaet Dortmund, 44221 Dortmund (Germany)

2012-01-10

265

16 CFR 613.1 - Duration of active duty alerts.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Duration of active duty alerts. 613.1 Section 613.1 Commercial...CREDIT REPORTING ACT DURATION OF ACTIVE DUTY ALERTS § 613.1 Duration of active duty alerts. The duration of an active duty alert...

2012-01-01

266

16 CFR 613.1 - Duration of active duty alerts.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Duration of active duty alerts. 613.1 Section 613.1 Commercial...CREDIT REPORTING ACT DURATION OF ACTIVE DUTY ALERTS § 613.1 Duration of active duty alerts. The duration of an active duty alert...

2011-01-01

267

16 CFR 613.1 - Duration of active duty alerts.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Duration of active duty alerts. 613.1 Section 613.1 Commercial...CREDIT REPORTING ACT DURATION OF ACTIVE DUTY ALERTS § 613.1 Duration of active duty alerts. The duration of an active duty alert...

2010-01-01

268

16 CFR 613.1 - Duration of active duty alerts.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Duration of active duty alerts. 613.1 Section 613.1 Commercial...CREDIT REPORTING ACT DURATION OF ACTIVE DUTY ALERTS § 613.1 Duration of active duty alerts. The duration of an active duty alert...

2009-01-01

269

Flow Duration at Selected Stream-Sites in Kentucky  

USGS Publications Warehouse

Flow duration characteristics were determined for 195 streamflow stations in Kentucky. The data includes flow duration tables for the period of record of the stations based on mean daily discharges. Seasonal flow durations are also presented from monthly analysis of the data. At sites affected by regulation, tables are published showing both the before and after regulation flow duration data. (USGS)

Quinones, F.; Kiesler, J.; Macy, J.

1980-01-01

270

Comparative Study in the Use of Brachial Photoplethysmography and the QRS Complex as Timing References in Determination of Pulse Transit Time.  

National Technical Information Service (NTIS)

For more than a century, there has been interest in pulse wave velocity and pulse transit time as a possible metric for blood pressure and other cardiovascular parameters. The most common approach in noninvasive measurement of these metrics has been to me...

M. Maguire T. Ward C. Markham D. O'Shea L. Kevin

2001-01-01

271

Postintervention duration of anticoagulation in venous surgery.  

PubMed

For a substantial proportion of patients with deep venous thrombosis (DVT), current treatment strategies are suboptimal and new treatment options are needed. Especially for the group of patients who are at the highest risk for post-thrombotic syndrome, new treatment modalities such as catheter-directed thrombolysis and additional stenting are being investigated. With current clinical studies addressing new technical options, the medical management of patients following these interventions deserves attention. The duration of anticoagulant treatment following surgical or radiological interventions for DVT seems not to be influenced by the presence of a venous stent. According to recent ACCP 2012 guidelines the anticoagulant management in patients who have had any method of thrombus removal performed, the same intensity and duration of anticoagulant therapy as in comparable patients who do not undergo thrombosis removal is recommended (Grade 1B). In the acute phase of thrombosis, irrespective of the technique and whether or not stenting is applied, immediate anticoagulation following the procedure is pertinent to reduce the risk of recurrent thrombosis and thrombus propagation. The long-term treatment duration after venous interventions therefore may be tailored based on common risk factors for recurrent thrombosis and the individual risk for bleeding. Selected thrombophilia factors, d-dimer assessment and residual venous thrombosis provide markers for recurrent DVT. Currently, vitamin K antagonists) provide the main anticoagulants for (prolonged) anticoagulation, while the new oral anticoagulants emerge as promising alternatives. In case prolonged anticoagulation after unprovoked DVT is not indicated, cardiovascular risk management is warranted because of an increased rate of arterial thrombotic events after DVT; aspirin may be indicated as secondary prevention against recurrent thrombosis (while providing primary prevention against arterial thrombosis). PMID:23482544

Ten Cate-Hoek, A J; Prins, M H; Wittens, C H A; ten Cate, H

2013-03-01

272

Caffeine intake reduces sleep duration in adolescents.  

PubMed

In our study, we hypothesized that higher caffeine intake would be associated with lower sleep duration among 13-year-old adolescents. In addition, we aimed to identify food sources of caffeine intake in this sample. Eligible participants were adolescents who were born in 1990 and attended school in Porto, Portugal, in 2003/2004. Self-administered questionnaires were used, and diet was evaluated using a food frequency questionnaire. From the 2160 eligible participants, only 1522 with valid information regarding their diet were included in this study. In our sample, the median intake of caffeine was 23.1 mg/d, with soft drinks being the major source. Ice tea presented the highest median (25th-75th percentiles) contribution (33.1% [14.0-52.1]), followed by cola (21.1% [6.4-37.6]). Regarding cocoa products, chocolate bars presented a median contribution of 5.1% (1.0-14.0), and snacks containing chocolate had a contribution of 3.0% (0.5-7.2). Coffee and tea presented a negligible contribution. Adolescents who reported less sleep duration and those who spent more time watching TV during the weekend had a significantly higher caffeine intake. Overall, boys had higher intakes of caffeine from soft drinks, and private school attendees, those who had parents with more education, who reported less television viewing time and had lower body mass index presented higher intakes of caffeine from chocolate. Considering sleeping more than 9.5 hours as a reference class, for each increase of 10 mg/d in caffeine intake, we found that the odds ratio of sleeping 8.5 hours or less was 1.12 (95% confidence interval, 1.06-1.19). Our results support the hypothesis that caffeine intake was inversely associated with sleep duration in adolescents. PMID:24034572

Lodato, Francesca; Araújo, Joana; Barros, Henrique; Lopes, Carla; Agodi, Antonella; Barchitta, Martina; Ramos, Elisabete

2013-09-01

273

Long Duration Exposure Facility space optics handbook  

NASA Astrophysics Data System (ADS)

This handbook provides a user a space optics design guide to materials based on the Long Duration Exposure Facility (LDEF) Space Optics Experiments. The materials covered are refractive optics, coatings, filters, mirrors, second surface mirrors, quartz microbalances, and fiber optics. The guide presents the data and the experience learned from the LDEF Space Optics Experiments in one volume in a user-friendly fashion. The data reported in the handbook are a compilation of the data published by the individual experimenters. Natural space environment data with an emphasis on the microparticle environment are also presented.

Kemp, William T.; Taylor, Edward; Bloemker, Carl; White, Frank; Rensner, Gary; Watts, Alan

1993-09-01

274

The extended duration orbiter waste collection system  

NASA Technical Reports Server (NTRS)

A new waste collection system (WCS) is undergoing development for use in the extended duration orbiter (EDO). Requirements for missions up to 18 days and the capability for missions up to 30 days necessitate the development of a new WCS that will have the appropriate capacity. The new system incorporates design features from both Skylab and Space Shuttle Orbiter WCSs. The system for EDO utilizes redundant fans and urine separators. Plans call for the new WCS to be implemented for OV-105 (Endeavor) as well as for EDO. This paper describes the design and development status of the new WCS.

Brasseaux, Hubert J., Jr.; Winkler, H. E.; North, Jeffrey D.; Orlando, Samuel P.

1990-01-01

275

Long duration human exposure to microgravity  

NASA Technical Reports Server (NTRS)

Looking toward the era of long duration manned spaceflight, questions remain regarding human adaptation to the weightless environment. In particular, bone calcium loss, cardiovascular deconditioning, and effects of radiation require further study. NASA has undertaken a series of experiments to increase the knowledge base of human adaptation to spaceflight. To date, results in the area of cardiovascular deconditioning countermeasures are the furthest advanced. The results from the upcoming SLS-1 mission will enhance knowledge in all areas. With continued research, there is every confidence that astronauts will be able to be kept healthy for long periods of time.

Huntoon, C. L.

1991-01-01

276

Pulmonary rehabilitation: timing, location, and duration.  

PubMed

Pulmonary rehabilitation programs vary in terms of duration and location. Differences also exists in the patients who are judged eligible for rehabilitation. This article reviews the options clinicians have to organize programs in terms of who should be referred, when, where, and for how long. There are several risk factors for lack of uptake and non-adherence to programs. Logistical aspects are also an important barrier. In terms of election, patients with muscle dysfunction are likely the best candidates for exercise training. Patients with exercise-induced symptoms and those after exacerbations should also be referred. PMID:24874126

Troosters, Thierry; Hornikx, Miek; Demeyer, Heleen; Camillo, Carlos A; Janssens, Wim

2014-06-01

277

The long duration exposure facility structural interface  

NASA Technical Reports Server (NTRS)

The development of an efficient structural interface between the Long Duration Exposure Facility (LDEF) and the space shuttle orbiter is discussed. Thermal gradients and manufacturing tolerances restrict the number of retention points in the shuttle to four with no more than three in one plane. Loads during the powered exit, high drag reentry, and landing are also critical factors in the location of retention points. A LDEF design is described that meets all requirements while avoiding the structural weight penalties associated with an asymmetrical arrangement. The ground handling and assembly problems are resolved in an economical and effective manner.

Long, M. J.

1981-01-01

278

Study of the restitution of action potential duration using the artificial neural network  

Microsoft Academic Search

It is widely accepted that the APD (action potential duration) restitution plays a key role in the initializing and maintaining of the reentry arrhythmias. The Luo–Rudy II models paced with different protocols showed that the current APD had a complex relation with the previous APDs and diastole intervals (DIs). This relation could not be accurately described by a single exponential

Xinwei Han; Yao Chen; Weihua Gao; Juel Xue; Xiaodong Han; Zuxiang Fang; Cuiwei Yang; Xiaomei Wu

2007-01-01

279

VOGUE: A variable order hidden Markov model with duration based on frequent sequence mining  

Microsoft Academic Search

We present VOGUE, a novel, variable order hidden Markov model with state durations, that combines two separate techniques for modeling complex patterns in sequential data: pattern mining and data modeling. VOGUE relies on a variable gap sequence mining method to extract frequent patterns with different lengths and gaps between elements. It then uses these mined sequences to build a variable

Mohammed J. Zaki; Christopher D. Carothers; Boleslaw K. Szymanski

2010-01-01

280

Duration of Nocturnal Hypoglycemia Before Seizures  

PubMed Central

OBJECTIVE—Despite a high incidence of nocturnal hypoglycemia documented by the use of continuous glucose monitoring (CGM), there are no reports in the literature of nocturnal hypoglycemic seizures while a patient is wearing a CGM device. RESEARCH DESIGN AND METHODS—In this article, we describe four such cases and assess the duration of nocturnal hypoglycemia before the seizure. RESULTS—In the cases where patients had a nocturnal hypoglycemic seizure while wearing a CGM device, sensor hypoglycemia (<60 mg/dl) was documented on the CGM record for 2.25–4 h before seizure activity. CONCLUSIONS—Even with a subcutaneous glucose lag of 18 min when compared with blood glucose measurements, glucose sensors have time to provide clinically meaningful alarms. Current nocturnal hypoglycemic alarms need to be improved, however, since patients can sleep through the current alarm systems.

Buckingham, Bruce; Wilson, Darrell M.; Lecher, Todd; Hanas, Ragnar; Kaiserman, Kevin; Cameron, Fergus

2008-01-01

281

Expanded capabilities of the Extended Duration Orbiter  

NASA Technical Reports Server (NTRS)

The Extended Duration Orbiter (EDO) is presented emphasizing the ability of the program to enhance the stay times of Spacelab, Spacehab, and Commercially Developed Space Facility missions. An overview of EDO is given with particular attention given to the modifications required for the implementation of Environmental Control and Life Support Systems specific to the Space Shuttle. The configuration, operation, and location of proposed regenerative CO2 removal, N2 supply, improved waste-collection, and power-reactant storage and distribution systems are described in detail. The EDO also includes a trash compactor, additional cryogenic hydrogen and oxygen, extra gaseous nitrogen, and a method for reducing stowed lithium hydroxide. The first utilization of the EDO system is a 13-day mission on the space shuttle Columbia planned for March 1992.

Cerna, Peter J.; Williams, David E.

1990-01-01

282

Short duration thermal metamorphism in CR chondrites  

NASA Astrophysics Data System (ADS)

CR chondrites are considered as one of the most primitive classes of meteorites. Most of them experienced a mild aqueous alteration and show no evidence of significant effect of thermal metamorphism. We present here a search for low degree metamorphic effects in CR chondrites. We studied 15 CR chondrites using different metamorphic indicators: (1) structure and Ni content of metal grains; (2) hydration state of matrix; (3) structure and composition of organic matter. The different metamorphic indicators show that two of the analyzed CR chondrites, GRA 06100 and GRO 03116, experienced thermal metamorphism. Indeed, all of the metal grains in GRA 06100 and half of the metal grains in GRO 03116 show Ni-rich phases; the matrix of GRA 06100 is almost completely dehydrated, and the matrix of GRO 03116 is partially dehydrated; Raman spectra of organic matter in these two meteorites are clearly different from those obtained for organic matter in the other CR chondrites, which resemble Raman spectra of organic matter in unmetamorphosed, CM2 meteorites; IR spectra of insoluble organic matter extracted from GRA 06100 and GRO 03116 show lower carbonyl abundance and higher CH2/CH3 ratio with respect to organic matter of unmetamorphosed chondrites. The other CR chondrites analyzed here lack these characteristics and only show a few metal grains with Ni-rich inclusions. Our results also show that the metamorphic effects observed in GRA 06100 and GRO 03116 are different from those observed in type 3 chondrites, which experienced long-duration metamorphism of radiogenic origin. We infer that thermal processing in these two CRs extended over a short duration and was triggered by impacts.

Briani, G.; Quirico, E.; Gounelle, M.; Paulhiac-Pison, M.; Montagnac, G.; Beck, P.; Orthous-Daunay, F.-R.; Bonal, L.; Jacquet, E.; Kearsley, A.; Russell, S. S.

2013-12-01

283

Nodoventricular pathway associated with twin AV nodes: complexity of ablation in single ventricle physiology.  

PubMed

We report the case of a patient with heterotaxy syndrome including complex single ventricular morphology and interrupted IVC in association with twin conduction systems and a nodoventricular accessory pathway connection. The presence of 3 distinct QRS morphologies was inadvertently discovered during a hemodynamic catheterization study and prompted formal EP testing prior to hepatic venous inclusion into the Fontan circuit and loss of access to the atrial chamber for testing and therapy. This patient underscores the importance of close surveillance and high index of suspicion of arrhythmia mechanisms in patients with heterotaxy syndrome in conjunction with single ventricle morphology. PMID:20132387

Czosek, Richard J; Anderson, Jeffrey; Connor, Chad; Knilans, Timothy

2010-08-01

284

15 CFR 2008.6 - Duration of original classification.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Duration of original classification. 2008.6 Section 2008.6 Commerce and Foreign Trade Regulations Relating...UNITED STATES TRADE REPRESENTATIVE Classification § 2008.6 Duration of original classification....

2010-01-01

285

Sprint performance-duration relationships are set by the fractional duration of external force application.  

PubMed

We hypothesized that the maximum mechanical power outputs that can be maintained during all-out sprint cycling efforts lasting from a few seconds to several minutes can be accurately estimated from a single exponential time constant (k(cycle)) and two measurements on individual cyclists: the peak 3-s power output (P(mech max)) and the maximum mechanical power output that can be supported aerobically (P(aer)). Tests were conducted on seven subjects, four males and three females, on a stationary cycle ergometer at a pedal frequency of 100 rpm. Peak mechanical power output (P(mech max)) was the highest mean power output attained during a 3-s burst; the maximum power output supported aerobically (P(aer)) was determined from rates of oxygen uptake measured during a progressive, discontinuous cycling test to failure. Individual power output-duration relationships were determined from 13 to 16 all-out constant load sprints lasting from 5 to 350 s. In accordance with the above hypothesis, the power outputs measured during all-out sprinting efforts were estimated to within an average of 34 W or 6.6% from P(mech max), P(aer), and a single exponential constant (k(cycle) = 0.026 s(-1)) across a sixfold range of power outputs and a 70-fold range of sprint trial durations (R2 = 0.96 vs. identity, n = 105; range: 180 to 1,136 W). Duration-dependent decrements in sprint cycling power outputs were two times greater than those previously identified for sprint running speed (k(run) = 0.013 s(-1)). When related to the respective times of pedal and ground force application rather than total sprint time, decrements in sprint cycling and running performance followed the same time course (k = 0.054 s(-1)). We conclude that the duration-dependent decrements in sprinting performance are set by the fractional duration of the relevant muscular contractions. PMID:16254125

Weyand, Peter G; Lin, Jennifer E; Bundle, Matthew W

2006-03-01

286

A comparison of financial duration models via density forecasts  

Microsoft Academic Search

Using density forecast evaluation techniques, we compare the predictive performance of econometric specifications that have been developed for modeling duration processes in intra-day financial markets. The model portfolio encompasses various variants of the Autoregressive Conditional Duration (ACD) model and recently proposed dynamic factor models. The evaluation is conducted on time series of trade, price and volume durations computed from transaction

Luc Bauwens; Pierre Giot; Joachim Grammig; David Veredas

2004-01-01

287

A comparison of financial duration models via density forecasts  

Microsoft Academic Search

Using density forecasts, we compare the predictive performance of duration models that have been developed for modelling intra-day data on stock markets. Our model portfolio encompasses the autoregressive conditional duration (ACD) model, its logarithmic version (Log-ACD), the threshold ACD (TACD) model - in each case with alternative error distributions -, the stochastic conditional duration model (SCD), and the stochastic volatility

Luc BAUWENS; Pierre GIOT; Joachim GRAMMIG; David VEREDAS

2000-01-01

288

Judging Relative Duration: The Role of Rule and Instructional Variables  

Microsoft Academic Search

Humans compared 2 durations according to different rules. Some judged which duration lasted longer, some judged whether the duration ratio was less or greater than 3:1, and others judged according to a same–different rule. Under each condition, ˝ of the participants had advance knowledge of the rule, whereas the others acquired the discrimination solely on the basis of informative feedback.

J. Gregor Fetterman; Leon R. Dreyfus; D. Alan Stubbs

1996-01-01

289

Time in Language: Event Duration in Language Comprehension  

ERIC Educational Resources Information Center

This work investigates how we process and represent event duration in on-line language comprehension. Specifically, it examines how events of different duration are processed and what type of knowledge underlies their representations. Studies 1-4 examined verbs and phrases in different contexts. They showed that durative events took longer to…

Coll-Florit, Marta; Gennari, Silvia P.

2011-01-01

290

The duration and convexity of convertible preferred stock: an extension  

Microsoft Academic Search

The purpose of this paper is to provide mathematical expressions for the duration and convexity of a convertible preferred stock. In general, the duration of a convertible preferred stock is the product of the Macaulay duration for a pure preferred stock and an elasticity measure that relates the convertible's price to the price of its straight preferred component. Convexity has

Ghassem Homaifar; Hassan Ehsani; John T. Lee

1994-01-01

291

Effects of Resource Allocation Policies on Project Durations  

Microsoft Academic Search

Minimizing duration is critical to success in many construction projects. As a primary driver of progress and an effective management tool, resource allocation among development activities can strongly influence durations. Limitations and costs of improving development processes and increasing resource quantities and productivities make improving resource allocation policies an important source of schedule improvement. Policies for reduced project duration are

Zee Woon Lee; David N. Ford; Nitin Joglekar

292

Dietary nutrients associated with short and long sleep duration. Data from a nationally representative sample?  

PubMed Central

Short sleep duration is associated with weight gain and obesity, diabetes, cardiovascular disease, psychiatric illness, and performance deficits. Likewise, long sleep duration is also associated with poor physical and mental health. The role of a healthy diet in habitual sleep duration represents a largely unexplored pathway linking sleep and health. This study evaluated associations between habitual sleep parameters and dietary/nutritional variables obtained via the National Health and Nutrition Examination Survey (NHANES), 2007–2008. We hypothesized that habitual very short (<5 h) short (5–6 h) and long (9+ h) sleep durations are associated with intake of a number of dietary nutrient variables. Overall, energy intake varied across very short (2036 kcal), short (2201 kcal), and long (1926 kcal) sleep duration, relative to normal (2151 kcal) sleep duration (p = 0.001). Normal sleep duration was associated with the greatest food variety (17.8), compared to very short (14.0), short (16.5) and long (16.3) sleep duration (p < 0.001). Associations between sleep duration were found across nutrient categories, with significant associations between habitual sleep duration and proteins, carbohydrates, vitamins and minerals. In stepwise analyses, significant contributors of unique variance included theobromine (long sleep RR = 0.910, p < 0.05), vitamin C (short sleep RR = 0.890, p < 0.05), tap water (short sleep RR = 0.952, p < 0.001; very short (<5 h) sleep RR = 0.941, p < 0.05), lutein + zeaxanthin (short sleep RR = 1.123, p < 0.05), dodecanoic acid (long sleep RR = 0.812, p < 0.05), choline (long sleep RR = 0.450, p = 0.001), lycopene (very short (<5 h) sleep RR = 0.950, p <0.05), total carbohydrate (very short (<5 h) sleep RR = 0.494, p <0.05; long sleep RR = 0.509, p <0.05), selenium (short sleep RR = 0.670, p <0.01) and alcohol (long sleep RR = 1.172, p < 0.01). Overall, many nutrient variables were associated with short and/or long sleep duration, which may be explained by differences in food variety. Future studies should assess whether these associations are due to appetite dysregulation, due to short/long sleep and/or whether these nutrients have physiologic effects on sleep regulation. In addition, these data may help us better understand the complex relationship between diet and sleep and the potential role of diet in the relationship between sleep and obesity and other cardiometabolic risks.

Grandner, Michael A.; Jackson, Nicholas; Gerstner, Jason R.; Knutson, Kristen L.

2013-01-01

293

Long Duration Richtmyer-Meshkov Instability Experiments  

NASA Astrophysics Data System (ADS)

This experimental study investigates the Richtmyer-Meshkov (RM) instability of an interface between incompressible, miscible liquids with an initial 2-D sinusoidal perturbation. The experiments are conducted in NASA Glenn Research Center's 2.2 Second Drop Tower. The experimental rig is isolated from aerodynamic drag by a surrounding drag shield. The rig falls 7 1/2 inches relative to the drag shield during the 79 ft fall of the system. An internal spring-driven sled impacting a clay ball provides the impulsive acceleration while the package is at the top of the drop tower, with the package timed to release just after the impulsive acceleration is complete. The instability evolves for 2.2 seconds until the package impacts an air bag at the bottom of the drop tower. The increased duration of these experiments provides for more than twice the observation time of the RM instability in the non-linear regime that will allow for better experimental comparison with asymptotic theories of perturbation amplitude and velocity.

Hunyadi, Sarah; Niederhaus, Charles; Jacobs, Jeffrey

2004-11-01

294

Long Duration Richtmyer-Meshkov Instability Experiments  

NASA Astrophysics Data System (ADS)

This experimental study investigates the Richtmyer-Meshkov (RM) instability of an interface between incompressible, miscible liquids with an initial 2-D sinusoidal perturbation. The experiments are conducted in NASA Glenn Research Center's 2.2 Second Drop Tower. The experimental rig is isolated from aerodynamic drag by a surrounding drag shield. The rig falls 7 1/2 inches relative to the drag shield during the 79 ft fall of the system. An internal spring-driven sled impacting a clay ball provides the impulsive acceleration while the package is at the top of the drop tower, with the package timed to release just after the impulsive acceleration is complete. The instability evolves for 2.2 seconds until the package impacts an air bag at the bottom of the drop tower. The increased duration of these experiments provides for more than twice the observation time of the RM instability in the non-linear regime that will allow for better experimental comparison with asymptotic theories of perturbation amplitude and velocity.

Niederhaus, Charles; Hunyadi, Sarah; Jacobs, Jeffrey

2003-11-01

295

Analysis of the duration of migraine prophylaxis.  

PubMed

To determine the minimum duration of migraine prophylaxis, after patients become pain-free. Migraine patients diagnosed according to criteria of International Classification of Headache Disorders-2 were treated prophylactically. After becoming pain-free, they were divided into two equal groups: in group 1, prophylaxis was maintained for another 12 months and in group 2, for 24 months. Each group was followed for more three years after prophylaxis period. Of the 50 patients, 39 (78%) were female and 11 (22%) were male. The age ranged from 18 to 50 years. Before treatment, the attack frequency for groups 1 and 2 was, respectively, 16.3 ± 12.8 and 16.4 ± 11.8 days per month (p = 0.769). Patients in groups 1 and 2 have become pain-free, respectively, with 21.4 ± 11.2 and 16.8 ± 9.9 months (p = 0.161). During three years without treatment, groups 1 and 2 maintained an annual frequency of respectively 3.2 and 0.5 headache days. Of the patients in group 2, 76.0% (19/25) remained pain-free during follow-up, versus 44.0% (11/25) of group 1, with a significant difference (p=0.001). The best results were obtained when migraine prophylaxis was maintained for 24 months after patients became pain-free. PMID:24308946

Silva-Néto, Raimundo Pereira; Almeida, Kelson James; Bernardino, Silvya Neri

2014-02-15

296

Immune changes during short-duration missions.  

PubMed

Spaceflight materially influences the immune mechanism of humans and animals. Effects resulting from missions of less than 1 month are examined. Effects from longer missions are discussed in the companion paper by Konstantinova et al. Most immunology studies have involved analyses of subjects and samples from subjects obtained after flight, with the data being compared with similar data obtained before flight. These studies have demonstrated that short-duration missions can result in a postflight depression in blast cell transformation, major changes in cytokine function, and alterations in the relative numbers of immune cell populations. In addition to these post- vs. preflight studies, some data have been produced in flight. However, these in vitro analyses have been less than satisfactory because of differences between in-flight and ground-control conditions. Recently, both the U.S. and Russian space programs have started collecting in-flight, in vivo, cell-mediated immunity data. These studies have confirmed that the human cell-mediated immune system is blunted during spaceflight. PMID:8371049

Taylor, G R

1993-09-01

297

Prolonged duration of fertility of dog ova.  

PubMed

The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2-3 days PO and viability of secondary oocytes for 48-60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 +/- 1.6 and 64.3 +/- 0.3 days, 4.0 +/- 1.4 and 66.3 +/- 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4-5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment. PMID:19754575

Tsutsui, T; Takahashi, F; Hori, T; Kawakami, E; Concannon, P W

2009-07-01

298

NASA's extended duration orbiter medical program  

NASA Technical Reports Server (NTRS)

The physiological issues involved in safely extending Shuttle flights from 10 to 16 days have been viewed by some as academic. After all, they reasoned, humans already have lived and worked in space for periods exceeding even 28 days in the United States Skylab Program and onboard the Russian space stations. The difference in the Shuttle program is in the physical position of the astronauts as they reenter the Earth's atmosphere. Crewmembers in the earlier Apollo, Skylab, and Russian programs were returned to Earth in the supine position. Space Shuttle crewmembers, in contrast, are seated upright during reentry and landing; reexperiencing the Earth's g forces in this position has far more pronounced effects on the crewmember's physiological functions. The goal of the Extended Duration Orbiter (EDO) Medical Project (EDOMP) has been to ensure that crewmembers maintain physiological reserves sufficient to perform entry, landing, and egress safely. Early in the Shuttle Program, it became clear that physiological deconditioning during space flight could produce significant symptoms upon return to Earth. The signs and symptoms observed during the entry, landing, and egress after Shuttle missions have included very high heart rates and low blood pressures upon standing. Dizziness, 'graying out,' and fainting have occurred on ambulation or shortly thereafter. Other symptoms at landing have included headache, light-headedness, nausea and vomitting, leg cramping, inability to stand for several minutes after wheel-stop, and unsteadiness of gait.

Pool, Sam Lee; Sawin, Charles F.

1992-01-01

299

Shortening ocular pain duration following intravitreal injections.  

PubMed

Purpose. To determine ocular pain duration after routine in-office intravitreal injection and to determine whether topical eyedrops are beneficial in increasing patient comfort. Methods. Forty injection-naďve patients receiving routine intravitreal injections of bevacizumab for age-related macular degeneration were randomized into 3 groups: group 1 (control, no drops), group 2 (generic artificial tears), and group 3 (ketorolac tromethamine 0.4% eyedrops). Those who received topical medications were given a Visual Analog Pain score survey and asked to record their pain on a scale from 0 (no distress) to 10 (unbearable distress) daily until a score of 0 was achieved, at which point they were instructed to discontinue use of their given drops. Self-reported pain scores were assessed. Results. Pain after routine intravitreal injection lasts on average between 3 and 7 days. Patients receiving topical ketorolac eyedrops reported the fewest average number of pain days (2.25±1.22) vs patients receiving artificial tears (3.54±1.13) or those who received no postprocedure eyedrops (5.13±1.25); p<0.05. At most, patients receiving ketorolac eyedrops reported 3 days of recordable pain. Those who received artificial tears reported at most 5 days of recordable pain, and patients who did not receive any postprocedure eyedrops reported at most 7 days of recordable pain. Conclusions. Pain after intravitreal injection is generally mild, may be reduced by postinjection topical ketorolac eyedrops, and lasts less than 1 week. PMID:22562296

Rifkin, Lana; Schaal, Shlomit

2012-04-24

300

Local and Duration Magnitudes in Western Anatolia  

NASA Astrophysics Data System (ADS)

Kandilli Observatory and Earthquake Research Institute (KOERI) National Earthquake Monitoring Center (NEMC) has a well-designed broadband seismic network throughout Turkey. The network consists of 107 broadband seismometers (CMG-3T, CMG-3ESP/C, CMG-40T). Two types of magnitude scales used for broadband stations at NEMC. Local magnitude (Ml) and duration magnitude (Md) are calibrated using broadband stations. From 2006 through 2010, we calculate Ml values for western Anatolia earthquakes using maximum amplitudes on digital records from synthetic Wood-Anderson seismographs. We determine empirical Ml station corrections that minimize differences between Ml’s calculated from different type of broadband sensors. Application of these station corrections, in combination with distance corrections from Richter (1958) which have been in use at NEMC since 2003, produces Ml values that do not show any significant distance dependence. Ml determinations for western Anatolia (Marmara and Aegean regions) for 2006-2010 using our station corrections and Richter’s distance corrections have provided a reliable data set for recalibrating the Md scales for these regions. Our revised Ml values are consistent with available moment magnitude determinations for the western Anatolia earthquakes. Finally Md is calibrated against revised Ml and empirical equations are determined both magnitude scales.

Gorgun, E.; Comoglu, M.; Koseoglu Kusmezer, A.; Kekovali, K.; Kalafat, D.

2010-12-01

301

Immune changes during short-duration missions  

NASA Technical Reports Server (NTRS)

Spaceflight materially influences the immune mechanism of humans and animals. Effects resulting from missions of less than 1 month are examined. Effects from longer missions are discussed in the companion paper by Konstantinova et al. Most immunology studies have involved analyses of subjects and samples from subjects obtained after flight, with the data being compared with similar data obtained before flight. These studies have demonstrated that short-duration missions can result in a postflight depression in blast cell transformation, major changes in cytokine function, and alterations in the relative numbers of immune cell populations. In addition to these post- vs. preflight studies, some data have been produced in flight. However, these in vitro analyses have been less than satisfactory because of differences between in-flight and ground-control conditions. Recently, both the U.S. and Russian space programs have started collecting in-flight, in vivo, cell-mediated immunity data. These studies have confirmed that the human cell-mediated immune system is blunted during spaceflight.

Taylor, G. R.

1993-01-01

302

Prolonged duration local anesthesia with minimal toxicity  

PubMed Central

Injectable local anesthetics that would last for many days could have a marked impact on periprocedural care and pain management. Formulations have often been limited in duration of action, or by systemic toxicity, local tissue toxicity from local anesthetics, and inflammation. To address those issues, we developed liposomal formulations of saxitoxin (STX), a compound with ultrapotent local anesthetic properties but little or no cytotoxicity. In vitro, the release of bupivacaine and STX from liposomes depended on the lipid composition and on whether dexamethasone was incorporated. In cell culture, bupivacaine, but not STX, was myotoxic (to C2C12 cells) and neurotoxic (to PC12 cells) in a concentration- and time-dependent manner. Liposomal formulations containing combinations of the above compounds produced sciatic nerve blockade lasting up to 7.5 days (with STX + dexamethasone liposomes) in male Sprague–Dawley rats. Systemic toxicity only occurred where high loadings of dexamethasone increased the release of liposomal STX. Mild myotoxicity was only seen in formulations containing bupivacaine. There was no nerve injury on Epon-embedded sections, and these liposomes did not up-regulate the expression of 4 genes associated with nerve injury in the dorsal root ganglia. These results suggest that controlled release of STX and similar compounds can provide very prolonged nerve blocks with minimal systemic and local toxicity.

Epstein-Barash, Hila; Shichor, Iris; Kwon, Albert H.; Hall, Sherwood; Lawlor, Michael W.; Langer, Robert; Kohane, Daniel S.

2009-01-01

303

Organizational determinants of outpatient substance abuse treatment duration in women.  

PubMed

Longer treatment duration has consistently been related to improved substance use outcomes. This study examined how tailored women's programming and organizational characteristics were related to duration in outpatient substance abuse treatment in women. Data were from two waves of a national outpatient substance abuse treatment unit survey (n = 571 in 1999/2000, n = 566 in 2005). Analyses were conducted separately for methadone and nonmethadone programs. Negative binomial regressions tested associations between organizational determinants, tailored programming, and women's treatment duration. Of the tailored programming services, childcare was significantly related to longer duration in the nonmethadone programs, but few other organizational factors were. Tailored programming was not associated to treatment duration in methadone programs, but ownership, affiliation, and accreditation were related to longer duration. Study findings suggest evidence for how external relationships related to resources, treatment constraints, and legitimacy may influence women's treatment duration. Methadone programs may be more vulnerable to external influences. PMID:19038526

Campbell, Cynthia I; Alexander, Jeffrey A; Lemak, Christy Harris

2009-07-01

304

Organizational Determinants of Outpatient Substance Abuse Treatment Duration in Women  

PubMed Central

Longer treatment duration has consistently been related to improved substance use outcomes. This study examined how tailored women's programming and organizational characteristics were related to duration in outpatient substance abuse treatment in women. Data were from two waves of a national outpatient substance abuse treatment unit survey (n=571 in 1999/2000, n=566 in 2005). Analyses were conducted separately for methadone and non-methadone programs. Negative binomial regressions tested associations between organizational determinants, tailored programming, and women's treatment duration. Of the tailored programming services, childcare was significantly related to longer duration in the non-methadone programs, but few other organizational factors were. Tailored programming was not associated to treatment duration in methadone programs, but ownership, affiliation, and accreditation were related to longer duration. Study findings suggest evidence for how external relationships related to resources, treatment constraints, and legitimacy may influence women's treatment duration. Methadone programs may be more vulnerable to external influences.

Alexander, Jeffrey A.; Lemak, Christy Harris

2009-01-01

305

Dependence on pulse duration and foil thickness in high-contrast-laser proton acceleration  

SciTech Connect

Experimental measurements of proton acceleration with high intensity and high-contrast short laser pulses have been carried out over an order of magnitude range in target thickness and laser pulse duration. The dependence of the maximum proton energy with these parameters is qualitatively supported by two-dimensional particle-in-cell simulations. They evidence that two regimes of proton acceleration can take place, depending on the ratio between the density gradient and the hot electron Debye length at the rear target surface. As this ratio can be affected by the target thickness, a complex interplay between pulse duration and target thickness is observed. Measurements and simulations support unexpected variations in the laser absorption and hot electron temperature with the pulse duration and laser intensity, for which density profile modification at the target front surface is the controlling parameter.

Flacco, A.; Sylla, F.; Malka, V. [Laboratoire d'Optique Appliquee, ENSTA-ParisTech, Ecole Polytechnique-ParisTech, CNRS UMR 7639, Chemin de la Huniere, 91761 Palaiseau Cedex (France); Veltcheva, M. [Laboratoire d'Optique Appliquee, ENSTA-ParisTech, Ecole Polytechnique-ParisTech, CNRS UMR 7639, Chemin de la Huniere, 91761 Palaiseau Cedex (France); Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Carrie, M.; Nuter, R.; Lefebvre, E. [CEA, DAM, DIF, 91297 Arpajon (France); Batani, D. [Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano (Italy)

2010-03-15

306

Endocardial focal activation originating from Purkinje fibers plays a role in the maintenance of long duration ventricular fibrillation.  

PubMed

Aim. To determine the role of repetitive endocardial focal activations and Purkinje fibers in the maintenance of long duration ventricular fibrillation (LDVF, VF>1 minute) in canine hearts in vivo. Methods. The study was conducted in electrophysiological laboratory of Shanghai Ruijin hospital from July 2010 to August 2012. A 64-electrode basket was introduced through a carotid artery into the left ventricle (LV) of 11 beagle dogs for global endocardial electrical mapping. In the Lugol's solution group (n=5), the subendocardium was ablated by washing with Lugol's solution. In the control group, (n=6) saline was used for ablation. Before and after saline or Lugol ablation, we determined QRS duration and QT/QTc interval in sinus rhythm (SR). We also measured the activation rates in the first 2 seconds of each minute during 7 minutes of VF for each group. If VF terminated spontaneously in less than 7 minutes, the VF segments used in activation rate analysis were reduced accordingly. Results. At the beginning of VF there was no difference between the groups in the activation rate. However, after 1 minute of LDVF the Lugol's solution group had significantly slower activation rate than the control group. In the control group, all episodes of LDVF (6/6) were successfully sustained for 7 minutes, while in the Lugol's solution group 4/5 episodes of LDVF spontaneously terminated before 7 minutes (4.8±1.4 minutes) (P=0.015). In the control group, at 5.1±1.3 minutes of LDVF, a successive, highly organized focal LV endocardial activation pattern was observed. During this period, activations partly arose in PF and spread to the working ventricular myocardium. Mapping analysis showed that these events were consistent with repetitive endocardial focal activations. No evidence of similar focal activations was observed in the Lugol's solution group. Conclusions. Repetitive endocardial focal activations in the LV endocardium may be associated with activation of subendocardial PFs. This mechanism may play an important role in the maintenance of LDVF. PMID:24778098

Lin, Changjian; Jin, Qi; Zhang, Ning; Zhou, Jian; Pang, Yang; Xin, Yangxun; Liu, Shaohua; Wu, Qiong; Wu, Liqun

2014-04-28

307

Endocardial focal activation originating from Purkinje fibers plays a role in the maintenance of long duration ventricular fibrillation  

PubMed Central

Aim To determine the role of repetitive endocardial focal activations and Purkinje fibers in the maintenance of long duration ventricular fibrillation (LDVF, VF>1 minute) in canine hearts in vivo. Methods The study was conducted in electrophysiological laboratory of Shanghai Ruijin hospital from July 2010 to August 2012. A 64-electrode basket was introduced through a carotid artery into the left ventricle (LV) of 11 beagle dogs for global endocardial electrical mapping. In the Lugol’s solution group (n?=?5), the subendocardium was ablated by washing with Lugol’s solution. In the control group, (n?=?6) saline was used for ablation. Before and after saline or Lugol ablation, we determined QRS duration and QT/QTc interval in sinus rhythm (SR). We also measured the activation rates in the first 2 seconds of each minute during 7 minutes of VF for each group. If VF terminated spontaneously in less than 7 minutes, the VF segments used in activation rate analysis were reduced accordingly. Results At the beginning of VF there was no difference between the groups in the activation rate. However, after 1 minute of LDVF the Lugol’s solution group had significantly slower activation rate than the control group. In the control group, all episodes of LDVF (6/6) were successfully sustained for 7 minutes, while in the Lugol’s solution group 4/5 episodes of LDVF spontaneously terminated before 7 minutes (4.8?±?1.4 minutes) (P?=?0.015). In the control group, at 5.1?±?1.3 minutes of LDVF, a successive, highly organized focal LV endocardial activation pattern was observed. During this period, activations partly arose in PF and spread to the working ventricular myocardium. Mapping analysis showed that these events were consistent with repetitive endocardial focal activations. No evidence of similar focal activations was observed in the Lugol’s solution group. Conclusions Repetitive endocardial focal activations in the LV endocardium may be associated with activation of subendocardial PFs. This mechanism may play an important role in the maintenance of LDVF.

Lin, Changjian; Jin, Qi; Zhang, Ning; Zhou, Jian; Pang, Yang; Xin, Yangxun; Liu, Shaohua; Wu, Qiong; Wu, Liqun

2014-01-01

308

Rainfall intensity-duration-frequency relationships derived from large partial duration series  

NASA Astrophysics Data System (ADS)

SummaryA procedure is proposed for basing intensity-duration-frequency (IDF) curves on partial duration series (PDS) which are substantially larger than those commonly used for this purpose. The PDS are derived from event maxima series (EMS), composed of the maximum average intensities, over a given duration, determined for all rainfall events recorded at a station. The generalized Pareto distribution (GP) is fitted to many PDS nested within the EMS and the goodness-of-fit is determined by the Anderson-Darling test. The best fitted distribution is selected for predicting intensities associated with the given duration and with a number of recurrence intervals. This procedure was repeated for eleven rainfall durations, from 5 to 240 min, at four stations of the Israel Meteorological Service. For comparison, the GP and the generalized extreme value (GEV) distributions were fitted to annual maxima series (AMS) and the Gumbel and lognormal distributions were fitted to the PDS and to the AMS at these stations. In almost all cases, the GP distribution well fits to ranges of PDS within an EMS, while in a few cases the best fit is fair only. Another result is that the GP distribution does not fit to AMS and to EMS. The GEV distribution well fits to most AMS, and fairly fits to the others. The Gumbel and the lognormal distributions well fit to most of the AMS and to a very few PDS. In most cases of good fits of different distributions, the predicted values by the different distributions are not much different from one another. This indicates the importance of good fit of the distribution and of the power of the AD test used for determining it. In most cases the best fit of the GP distribution is to a PDS series substantially larger than its corresponding AMS. In most cases, the standard error of the estimated 100-year intensity, through the best fitted GP to PDS, is smaller than that estimated through the GEV fitted to the corresponding AMS. All these make the proposed procedure superior to the current ones. It also enables interpolated predictions down to recurrence intervals of N/ n years ( N is number of years of complete records and n is PDS size). The use of large samples would reduce the sensitivity of predicted intensities to sampling variations.

Ben-Zvi, Arie

2009-03-01

309

The ATIC Long Duration Balloon Project  

NASA Technical Reports Server (NTRS)

Long Duration Balloon (LDB) scientific experiments, launched to circumnavigate the south pole over Antarctica, have particular advantages compared to Shuttle or other Low Earth Orbit (LEO) missions in terms of cost, weight, scientific 'duty factor' and work force development. The Advanced Thin Ionization Calorimeter (ATIC) cosmic ray astrophysics experiment is a good example of a university-based project that takes full advantage of current LDB capability. The ATIC experiment is currently being prepared for its first LDB science flight that will investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10(exp 10) to 10(exp 14) eV. The instrument is built around a fully active, Bismuth Germanate (BGO) ionization calorimeter to measure the energy deposited by the cascades formed by particles interacting in a thick carbon target. A highly segmented silicon matrix, located above the target, provides good incident charge resolution plus rejection of the 'backscattered' particles from the interaction. Trajectory reconstruction is based on the cascade profile in the BGO calorimeter, plus information from the three pairs of scintillator hodoscope layers in the target section above it. A full evaluation of the experiment was performed during a test flight occurring between 28 December 2000 and 13 January 2001 where ATIC was carried to an altitude of approx. 37 km above Antarctica by an approx. 850,000 cu m helium filled balloon for one circumnavigation of the continent. All systems behaved well, the detectors performed as expected, more than 43 gigabytes of engineering and cosmic ray event data was returned and these data are now undergoing preliminary data analysis. During the coming 2002-2003 Antarctica summer season, we are preparing for a ATIC science flight with approx. 15 to 30 days of continuous data collection in the near-space environment of LDB float altitudes.

Guzik, T. G.; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Granger, D.; Gunasingha, R.

2003-01-01

310

Duration of patients' visits to the hospital emergency department  

PubMed Central

Background Length of stay is an important indicator of quality of care in Emergency Departments (ED). This study explores the duration of patients’ visits to the ED for which they are treated and released (T&R). Methods Retrospective data analysis and multivariate regression analysis were conducted to investigate the duration of T&R ED visits. Duration for each visit was computed by taking the difference between admission and discharge times. The Healthcare Cost and Utilization Project (HCUP) State Emergency Department Databases (SEDD) for 2008 were used in the analysis. Results The mean duration of T&R ED visit was 195.7 minutes. The average duration of ED visits increased from 8 a.m. until noon, then decreased until midnight at which we observed an approximately 70-minute spike in average duration. We found a substantial difference in mean duration of ED visits (over 90 minutes) between Mondays and other weekdays during the transition time from the evening of the day before to the early morning hours. Black / African American patients had a 21.4-minute longer mean duration of visits compared to white patients. The mean duration of visits at teaching hospitals was substantially longer than at non-teaching hospitals (243.8 versus 175.6 minutes). Hospitals with large bed size were associated with longer duration of visits (222.2 minutes) when compared to hospitals with small bed size (172.4 minutes) or those with medium bed size (166.5 minutes). The risk-adjusted results show that mean duration of visits on Mondays are longer by about 4 and 9 percents when compared to mean duration of visits on non-Monday workdays and weekends, respectively. Conclusions The duration of T&R ED visits varied significantly by admission hour, day of the week, patient volume, patient characteristics, hospital characteristics and area characteristics.

2012-01-01

311

Some exposure duration effects in simple reaction time  

Microsoft Academic Search

Studied simple reaction time (RT) as a function of exposure duration in 3 successive conditions using 4 trained university students: (a) foveal stimulation-target luminance constant, (b) nonfoveal stimulation-target luminance constant, and (c) foveal stimulation-target luminance randomly but slightly varying. Evidence was found for a critical duration beyond which RT increased with exposure duration in both foveal conditions. Within the critical

Ira H. Bernstein; D. Gregory Futch; D. L. Schurman

1973-01-01

312

Enhancing Team Performance for Long-Duration Space Missions  

NASA Technical Reports Server (NTRS)

Success of exploration missions will depend on skilled performance by a distributed team that includes both the astronauts in space and Mission Control personnel. Coordinated and collaborative teamwork will be required to cope with challenging complex problems in a hostile environment. While thorough preflight training and procedures will equip creW'S to address technical problems that can be anticipated, preparing them to solve novel problems is much more challenging. This presentation will review components of effective team performance, challenges to effective teamwork, and strategies for ensuring effective team performance. Teamwork skills essential for successful team performance include the behaviors involved in developing shared mental models, team situation awareness, collaborative decision making, adaptive coordination behaviors, effective team communication, and team cohesion. Challenges to teamwork include both chronic and acute stressors. Chronic stressors are associated with the isolated and confined environment and include monotony, noise, temperatures, weightlessness, poor sleep and circadian disruptions. Acute stressors include high workload, time pressure, imminent danger, and specific task-related stressors. Of particular concern are social and organizational stressors that can disrupt individual resilience and effective mission performance. Effective team performance can be developed by training teamwork skills, techniques for coping with team conflict, intracrew and intercrew communication, and working in a multicultural team; leadership and teamwork skills can be fostered through outdoor survival training exercises. The presentation will conclude with an evaluation of the special requirements associated with preparing crews to function autonomously in long-duration missions.

Orasanu, Judith M.

2009-01-01

313

Rashes and Exanthems on Long Duration Space Flights  

NASA Technical Reports Server (NTRS)

INTRODUCTION: As NASA expands its human space exploration to the Moon, Mars and beyond, it will be presented with many challenges, not the least of which will be dealing with medical conditions, which on earth are simple, but take on new levels of complexity in space habitats. Skin conditions exemplify this complexity. METHODS AND RESULTS: While skin conditions account for 7 % of outpatient presentations to a primary care provider in the United States, NASA Longitudinal Study of Astronaut Health (LSAH) database indicates that cutaneous manifestations are significantly prevalent on-orbit. Reviewing this data for US astronauts, there have been 90 total cases of skin rashes during 27.34 person-years of spaceflight, or 3.29 cases/person. Specifically, STS-1 though 114 had 56 cases, ISS Expeditions 1 though 13 had 7 cases, Mir had 4 cases, Skylab had 5 cases and the Apollo program had 18 cases. If there was a period of 24 hours or more between rashes in the same crewmember, this was counted as an additional case. DISCUSSION: This prevalence is likely due, in some part, to constraints of hygiene and to immunologic changes that occur. The stresses of microgravity and austere Earth environments such as the Antarctic, submarine and military deployments, no doubt, similarly contribute to cutaneous reactions; but the difference of the environments are significant enough to warrant further study and discussion. This paper will discuss rashes, exanthems, and cutaneous reactions in space habitats; it will address diagnosis, causation, mitigation and treatment of skin conditions seen on orbit, to date, with a look to anticipating what may be seen with larger crews on future extended duration expeditions.

Ilscus, L.S.; Johnston, S.L.; Moynihan, S.; Kerstman, E.L.; Marshall, G.D.

2009-01-01

314

Dutch and English listeners' interpretation of vowel duration  

PubMed Central

Dutch and English listeners’ interpretation of vowel duration changes was examined in a word transcription task. Listeners were presented with spoken words realized with canonical or altered vowel durations. Dutch listeners often misperceived lengthened short vowels and shortened long vowels, identifying them as the short?long counterpart of the target, whereas English listeners more rarely misidentified words with altered vowel duration. Although Dutch and English are similar prosodically and phonologically, listeners’ treatment of vowel duration in clear speech is different across the two languages.

van der Feest, Suzanne V. H.; Swingley, Daniel

2011-01-01

315

Factors that Influence Weekday Sleep Duration in European Children  

PubMed Central

Study Objectives: To compare nocturnal sleep duration in children from 8 European countries and identify its determinants. Design: Cross-sectional. Setting: Primary schools and preschools participating in the IDEFICS study. Participants: 8,542 children aged 2 to 9 years from 8 European countries with complete information on nocturnal sleep duration. Interventions: Not applicable. Measurements: Nocturnal sleep duration was assessed by means of a computer based parental 24-h recall. Data on personal, social, environmental, and behavioral factors were collected by means of standardized parental questionnaire. Physical activity was surveyed with accelerometers. Results: Nocturnal sleep duration in the participating countries ranged from 9.5 h (SD 0.8) in Estonia to 11.2 h (SD 0.7) in Belgium and differed significantly between countries (P < 0.001) in univariate as well as in multivariate analyses, with children from northern countries sleeping the longest. Sleep duration decreased by about 6 min with each year of age over all countries. No effect of season, daylight duration, overweight, parental education level, or lifestyle factors could be seen. Conclusion: Sleep duration differs significantly between countries. Our findings allow for the conclusion that regional affiliation, including culture and environmental characteristics, seems to overlay individual determinants of sleep duration. Citation: Hense S; Barba G; Pohlabeln H; De Henauw S; Marild S; Molnar D; Moreno LA; Hadjigeorgiou C; Veidebaum T; Ahrens W. Factors that influence weekday sleep duration in European children. SLEEP 2011;34(5):633-639.

Hense, Sabrina; Barba, Gianvincenzo; Pohlabeln, Hermann; De Henauw, Stefaan; Marild, Staffan; Molnar, Denes; Moreno, Luis A.; Hadjigeorgiou, Charalampos; Veidebaum, Toomas; Ahrens, Wolfgang

2011-01-01

316

The Mission Execution Crew Assistant: Improving Human Machine Team Resilience for Long Duration Missions  

Microsoft Academic Search

Manned long-duration missions to the Moon and Mars set high operational, human factors and technical demands for a distributed support system, which enhances human-machine teams' capabilities to cope autonomously with unexpected, complex and potentially hazardous situations. Based on a situated Cognitive Engineering (sCE) method, we specified a theoretical and empirical founded Requirements Baseline (RB) for such a system (called Mission

M. A. Neerincx; U. Brauer; M. Wolff

317

Long duration balloon flights - A probe for deep hard X-ray astronomy investigation  

Microsoft Academic Search

An assessment is presented of the progress to date in hard X-ray astronomy, with attention to the use of long duration balloon flights carrying the sensitive and complex payloads needed for observations in the 15-300 keV range, and the comparative performance of balloon and satellite observational platforms. Both galactic and extragalactic balloon-borne observation results are considered. It is noted that

P. Ubertini

1983-01-01

318

Sleep Duration and Depressive Symptoms: A Gene-Environment Interaction  

PubMed Central

Objective: We used quantitative genetic models to assess whether sleep duration modifies genetic and environmental influences on depressive symptoms. Method: Participants were 1,788 adult twins from 894 same-sex twin pairs (192 male and 412 female monozygotic [MZ] pairs, and 81 male and 209 female dizygotic [DZ] pairs] from the University of Washington Twin Registry. Participants self-reported habitual sleep duration and depressive symptoms. Data were analyzed using quantitative genetic interaction models, which allowed the magnitude of additive genetic, shared environmental, and non-shared environmental influences on depressive symptoms to vary with sleep duration. Results: Within MZ twin pairs, the twin who reported longer sleep duration reported fewer depressive symptoms (ec = -0.17, SE = 0.06, P < 0.05). There was a significant gene × sleep duration interaction effect on depressive symptoms (a'c = 0.23, SE = 0.08, P < 0.05), with the interaction occurring on genetic influences that are common to both sleep duration and depressive symptoms. Among individuals with sleep duration within the normal range (7-8.9 h/night), the total heritability (h2) of depressive symptoms was approximately 27%. However, among individuals with sleep duration within the low (< 7 h/night) or high (? 9 h/night) range, increased genetic influence on depressive symptoms was observed, particularly at sleep duration extremes (5 h/night: h2 = 53%; 10 h/night: h2 = 49%). Conclusion: Genetic contributions to depressive symptoms increase at both short and long sleep durations. Citation: Watson NF; Harden KP; Buchwald D; Vitiello MV; Pack AI; Stachan E; Goldberg J. Sleep duration and depressive symptoms: a gene-environment interaction. SLEEP 2014;37(2):351-358.

Watson, Nathaniel F.; Harden, Kathryn Paige; Buchwald, Dedra; Vitiello, Michael V.; Pack, Allan I.; Strachan, Eric; Goldberg, Jack

2014-01-01

319

Relationship between value and duration of construction projects  

Microsoft Academic Search

A strong relationship exists between the cost and duration of construction projects. This relationship can be used in contractors' budgeting systems and the corporate financial model developed at Loughborough University (Kaka, 1990). The client can use this relationship to estimate the approximate duration of a project and compare it with the proposed ones.Two samples were collected to model this relationship.

Ammar Kaka; A. D. F. Price

1991-01-01

320

Investigation of Depth-Area-Duration Curves for Kurdistan Province  

Microsoft Academic Search

Determining Depth-Area-Duration (DAD) curves in drainage basins is one of the applied researches in hydrology. DAD curves exhibit the depth and the area covered by the rainfall with a particular duration. DAD analysis is widely used in characterizat ion of precipitation extremes for specification of so -called design storms. In this study the DAD curves for the Kurdistan province were

Shirko Ebrahimi Mohammadi; Mohammad Mahdavi

321

Physiology, Medicine, Long-Duration Space Flight and the NSBRI  

Microsoft Academic Search

The hazards of long-duration space flight are real and unacceptable. In order for humans to participate effectively in long-duration orbital missions or continue the exploration of space, we must first secure the health of the astronaut and the success of such missions by assessing in detail the biomedical risks of space flight and developing countermeasures to these hazards. Acquiring the

R. J. White; J. P. Sutton; J. C. McPhee

2002-01-01

322

20 CFR 617.15 - Duration of TRA.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Duration of TRA. 617.15 Section 617.15 Employees' Benefits...TRADE ACT OF 1974 Trade Readjustment Allowances (TRA) § 617.15 Duration of TRA. (a) Basic weeks. An individual shall...

2009-04-01

323

20 CFR 617.15 - Duration of TRA.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Duration of TRA. 617.15 Section 617.15 Employees' Benefits...TRADE ACT OF 1974 Trade Readjustment Allowances (TRA) § 617.15 Duration of TRA. (a) Basic weeks. An individual shall...

2010-04-01

324

Physiology, medicine, long-duration space flight and the NSBRI  

Microsoft Academic Search

The hazards of long-duration space flight are real and unacceptable. In order for humans to participate effectively in long-duration orbital missions or continue the exploration of space, we must first secure the health of the astronaut and the success of such missions by assessing in detail the biomedical risks of space flight and developing countermeasures to these hazards. Acquiring the

R. J. White

2003-01-01

325

40 CFR 147.2910 - Duration of authorization by rule.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Duration of authorization by rule. 147.2910 Section 147.2910 Protection...147.2910 Duration of authorization by rule. Existing Class II injuction wells are authorized for the life of the well, subject to the obligation...

2013-07-01

326

40 CFR 85.2303 - Duration of model year.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Duration of model year. 85.2303 Section 85.2303...FROM MOBILE SOURCES Determination of Model Year for Motor Vehicles and Engines Used...Clean Air Act § 85.2303 Duration of model year. A specific model year...

2013-07-01

327

Return Migration, Wage Differentials, and the Optimal Migration Duration  

Microsoft Academic Search

In simple static models, migration increases with the wage differential between host and home country. In a dynamic framework, and if migrations are temporary, the size of the migrant population in the host country depends also on the migration duration. This paper analyses optimal migration durations in a model which rationalises the decision of the migrant to return to his

Christian Dustmanna

2001-01-01

328

Duration of symptoms in patients with infective endocarditis  

Microsoft Academic Search

Despite progress in the management of infective endocarditis, delays in diagnosis or prior antimicrobial treatment may adversely influence the symptom duration and outcome. The duration of symptoms in patients with infective endocarditis was studied in 683 cases among 653 patients with 703 episodes of the disease; patients were hospitalized within 10 days of symptom onset in 169 (24.7%) cases. Antimicrobial

Victor Sarli Issa; José Fabri; Pablo M. A. Pomerantzeff; Max Grinberg; Antonio Carlos Pereira-Barreto; Alfredo José Mansur

2003-01-01

329

Competitive routing of virtual circuits with unknown duration  

Microsoft Academic Search

In this paper we present a strategy to route unknown duration virtual circuits in a highspeed communication network. Previous work on virtual circuit routing concentrated on the case where the call duration is known in advance. We show that by allowing O(logn) reroutes per call, we can achieve O(logn) competitive ratio with respect to the maximum load (congestion) for the

Baruch Awerbuch; Yossi Azart; Serge A. Plotkin; Orli Waarts

1994-01-01

330

Leaving Teaching in the UK: A Duration Analysis  

Microsoft Academic Search

In this paper, the authors analyze the decision by teachers to leave the profession. Their results affirm the importance of relative earnings in the tenure and turnover decisions of teachers. The econometric modeling approach used yields important insights into the appropriateness of adopting a flexible, semiparametric specification of the duration dependence structure and of the unobserved heterogeneity distribution in duration

Peter J Dolton; Wilbert van der Klaauw

1995-01-01

331

Internal Clock Processes and the Filled-Duration Illusion  

ERIC Educational Resources Information Center

In 3 experiments, the authors compared duration judgments of filled stimuli (tones) with unfilled ones (intervals defined by clicks or gaps in tones). Temporal generalization procedures (Experiment 1) and verbal estimation procedures (Experiments 2 and 3) all showed that subjective durations of the tones were considerably longer than those of…

Wearden, John H.; Norton, Roger; Martin, Simon; Montford-Bebb, Oliver

2007-01-01

332

Using duration and pitch for mandarin digit string recognition  

Microsoft Academic Search

Mandarin digit string recognition (MDSR) is a challenge because there exist many difficulties in acoustic discrimination for such a small vocabulary speech recognition task. In this paper, we propose to improve MDSR performance by using duration and pitch information. Speech rate dispersion is used to involve duration knowledge and is incorporated in the MDSR system by rescoring the N-best candidates

Rui Zhao; Y. Kida; Xiang Yan; Pei Ding; Lei He

2010-01-01

333

Incidence and Duration of Breastfeeding in Active Duty Military Women.  

National Technical Information Service (NTIS)

The purpose of this investigation was to examine the incidence and duration of breastfeeding in active duty women in the armed forces. No data existed regarding the duration of breastfeeding for these women. A convenience sample of 20 active duty women wh...

D. Sandercock

1993-01-01

334

Stimulus Duration Preference at Electrode Sites Yielding Elicited Behavior  

NASA Technical Reports Server (NTRS)

The latency to display eating or drinking during hypothalamic stimulation was compared with the preferred duration of the same stimulus intensity in a self-stimulation situation. All the animals preferred longer stimulus durations than those required to elicit eating or drinking

Cox, V. C.

1970-01-01

335

Communication apprehension and motivation as predictors of public speaking duration  

Microsoft Academic Search

Communication apprehension (CA) has attracted considerable attention in the research literature over the past fifteen years. The present study attempted to predict the duration of informative speeches using an interactive model employing CA scores and estimates of situational motivation. Results indicated that CA alone accounted for a significant but small proportion of variance in speech duration. However, a full regression

Michael J. Beatty; Edmund C. Forst; Robert A. Stewart

1986-01-01

336

Unemployment Insurance and Male Unemployment Duration in Canada  

Microsoft Academic Search

A model of unemployment duration is estimated with weekly micro data on Canadian men. Ent itlement provisions in the unemployment insurance program and demand conditions are found to have a significant effect on the probability of leaving unemployment. The probability of a worker leaving unemploy ment declines with the duration of unemployment, holding unemployment insurance entitlement constant. When entitlement is

John C. Ham

1987-01-01

337

Bargaining over International Multilateral Agreements: The Duration of Negotiations  

Microsoft Academic Search

This article examines the duration of international multilateral agreement negotiations. Based on propositions in the literature concerning factors which may have an effect on the length of negotiations, I derive testable hypotheses concerning the involvement of intergovernmental and nongovernmental organizations in the negotiation process, the number of negotiating parties, and the duration of the agreement. These hypotheses are tested using

Nicole M. Simonelli

2011-01-01

338

Depth-duration frequency of precipitation for Texas  

USGS Publications Warehouse

The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, conducted a study of the depth-duration frequency of precipitation for Texas. Depth-duration frequency is an estimate of the depth of precipitation for a specified duration and frequency or recurrence interval. For this report, precipitation durations of 15, 30, and 60 minutes; 1, 2, 3, 6, 12, and 24 hours; and 1, 2, 3, 5, and 7 days were investigated. The recurrence intervals for the frequencies range from 2 to 500 years. The time series of precipitation annual maxima for 173 fifteen-minute, 274 hourly, and 865 daily National Weather Service precipitation stations with at least 10 years of record in Texas provide the basis of depth-duration frequency for each identified duration. In total, about 3,030; 10,160; and 38,120 cumulative years of record are available for the 15-minute, hourly, and daily stations, respectively. L-moment statistics of the precipitation annual maxima were calculated for each duration and for each station using unbiased L-moment estimators. The statistics calculated were the mean, L-scale, L-coefficient of variation, L-skew, and L-kurtosis. The mean for each station and duration was corrected for the bias associated with fixed-interval recording of precipitation. The generalized logistic distribution was determined, using L-moment ratio diagrams, as an appropriate probability distribution for modeling the frequency of annual maxima for durations of 15 minutes to 24 hours; whereas, the generalized extreme-value distribution was determined as appropriate for durations of 1 to 7 days. The location, scale, and shape parameters of the distributions for each duration and each station were calculated from the L-moments. These parameters were contoured using spatial interpolation, based on the geostatistical method of kriging, to produce 37 maps that depict the spatial variation and magnitude of each parameter. Contour maps of the shape parameter for the generalized extreme-value distribution for durations of 1 to 7 days are not presented; the root mean square errors of preliminary maps for 1- to 7-day shape parameters were not appreciably smaller than the statewide standard deviation. Therefore, a single statewide mean shape parameter was used for 1- to 7-day durations. The depth-duration frequency for any location in Texas can be estimated using the contour maps and the equation of the corresponding distribution.

Asquith, William H.

1998-01-01

339

Self-reported sleep duration in Finnish general population.  

PubMed

Self-reported short or long sleep duration has been repeatedly found to be associated with increased mortality and health risks. However, there is still an insufficient amount of detailed knowledge available to characterize the short and long sleep duration groups in general population. Consequently, the underlying mechanisms potentially explaining the health risks associated with short and long sleep duration are unclear. In the present study, the self-reported sleep duration in a sample of Finnish general population was studied, and its possible associations with such factors as self-perceived health, sociodemographic characteristics, lifestyle, sleep difficulties and daytime concomitants were analyzed. In particular, an effort was made to define mutually statistically-independent determinants of sleep duration. In the Finnish Health 2000 Survey, a representative sample of 8,028 subjects of 30 years of age or older and a sample of 1,894 subjects of 18-29 years of age were invited to take part in the health interview and health examination. The participation rate of the study was over 80%. The most important and statistically-independent determinants of short and long sleep duration were gender, physical tiredness, sleep problems, marital status, main occupation and physical activity. However, in the multivariable model they only accounted for approximately 16% of the variance in sleep duration in short and long sleepers, suggesting multiple sources of variance. The present study also suggests a dose-response like relationship between the sleep duration and many of its determinants within both short and long sleepers. A more detailed analysis of the clinical status of the short and long sleep duration groups is needed to evaluate the possible importance of these findings for health risks associated with sleep duration. PMID:16911030

Kronholm, Erkki; Härmä, Mikko; Hublin, Christer; Aro, Arja R; Partonen, Timo

2006-09-01

340

Sequential forecast of incident duration using Artificial Neural Network models.  

PubMed

This study creates an adaptive procedure for sequential forecasting of incident duration. This adaptive procedure includes two adaptive Artificial Neural Network-based models as well as the data fusion techniques to forecast incident duration. Model A is used to forecast the duration time at the time of incident notification, while Model B provides multi-period updates of duration time after the incident notification. These two models together provide a sequential forecast of incident duration from the point of incident notification to the incident road clearance. Model inputs include incident characteristics, traffic data, time gap, space gap, and geometric characteristics. The model performance of mean absolute percentage error for forecasted incident duration at each time point of forecast are mostly under 40%, which indicates that the proposed models have a reasonable forecast ability. With these two models, the estimated duration time can be provided by plugging in relevant traffic data as soon as an incident is reported. Thereby travelers and traffic management units can better understand the impact of the existing incident. Based on the model effect assessments, this study shows that the proposed models are feasible in the Intelligent Transportation Systems (ITS) context. PMID:17303059

Wei, Chien-Hung; Lee, Ying

2007-09-01

341

Forecasting the duration of volcanic eruptions: an empirical probabilistic model  

NASA Astrophysics Data System (ADS)

The ability to forecast future volcanic eruption durations would greatly benefit emergency response planning prior to and during a volcanic crises. This paper introduces a probabilistic model to forecast the duration of future and on-going eruptions. The model fits theoretical distributions to observed duration data and relies on past eruptions being a good indicator of future activity. A dataset of historical Mt. Etna flank eruptions is presented and used to demonstrate the model. The data have been compiled through critical examination of existing literature along with careful consideration of uncertainties on reported eruption start and end dates between the years 1300 AD and 2010. Data following 1600 is considered to be reliable and free of reporting biases. The distribution of eruption duration between the years 1600 and 1669 is found to be statistically different from that following it and the forecasting model is run on two datasets of Mt. Etna flank eruption durations: 1600-2010 and 1670-2010. Each dataset is modelled using a log-logistic distribution with parameter values found by maximum likelihood estimation. Survivor function statistics are applied to the model distributions to forecast (a) the probability of an eruption exceeding a given duration, (b) the probability of an eruption that has already lasted a particular number of days exceeding a given total duration and (c) the duration with a given probability of being exceeded. Results show that excluding the 1600-1670 data has little effect on the forecasting model result, especially where short durations are involved. By assigning the terms `likely' and `unlikely' to probabilities of 66 % or more and 33 % or less, respectively, the forecasting model based on the 1600-2010 dataset indicates that a future flank eruption on Mt. Etna would be likely to exceed 20 days (± 7 days) but unlikely to exceed 86 days (± 29 days). This approach can easily be adapted for use on other highly active, well-documented volcanoes or for different duration data such as the duration of explosive episodes or the duration of repose periods between eruptions.

Gunn, L. S.; Blake, S.; Jones, M. C.; Rymer, H.

2014-01-01

342

Vehicle Routing Problem with Time Windows: Minimizing Route Duration.  

National Technical Information Service (NTIS)

The author investigates the implementation of edge-exchange improvement methods for the vehicle routing problem with time windows with minimization of route duration as the objective. The presence of time windows as well as the chosen objective cause veri...

M. W. P. Savelsbergh

1991-01-01

343

Long Duration Exposure Facility (LDEF). Mission 1 Experiments  

NASA Technical Reports Server (NTRS)

Spaceborne experiments using the space shuttle payload known as the Long Duration Exposure Facility are described. Experiments in the fields of materials, coatings, thermal systems, power and propulsion, electronic, and optics are discussed.

Clark, L. G. (editor); Kinard, W. H. (editor); Carter, D. L., Jr. (editor); Jones, J. L., Jr. (editor)

1984-01-01

344

10 CFR 451.6 - Duration of incentive payments.  

Code of Federal Regulations, 2011 CFR

...Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration...payments under this part with respect to a qualified renewable energy facility for 10 consecutive fiscal...

2011-01-01

345

10 CFR 451.6 - Duration of incentive payments.  

Code of Federal Regulations, 2012 CFR

...Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration...payments under this part with respect to a qualified renewable energy facility for 10 consecutive fiscal...

2012-01-01

346

10 CFR 451.6 - Duration of incentive payments.  

Code of Federal Regulations, 2010 CFR

...Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration...payments under this part with respect to a qualified renewable energy facility for 10 consecutive fiscal...

2010-01-01

347

10 CFR 451.6 - Duration of incentive payments.  

...Section 451.6 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION RENEWABLE ENERGY PRODUCTION INCENTIVES § 451.6 Duration...payments under this part with respect to a qualified renewable energy facility for 10 consecutive fiscal...

2014-01-01

348

49 CFR 385.715 - Duration of safety monitoring system.  

Code of Federal Regulations, 2013 CFR

...FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS SAFETY FITNESS PROCEDURES Safety Monitoring System for Non-North American Carriers § 385.715 Duration of safety monitoring...

2013-10-01

349

49 CFR 385.117 - Duration of safety monitoring system.  

Code of Federal Regulations, 2013 CFR

...FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS SAFETY FITNESS PROCEDURES Safety Monitoring System for Mexico-Domiciled Carriers § 385.117 Duration of safety monitoring...

2013-10-01

350

Vocal corollary discharge communicates call duration to vertebrate auditory system.  

PubMed

Corollary discharge is essential to an animal's ability to filter self-generated from external stimuli. This includes acoustic communication, although direct demonstration of a corollary discharge that both conveys a vocal motor signal and informs the auditory system about the physical attributes of a self-generated vocalization has remained elusive for vertebrates. Here, we show the underlying synaptic activity of a neuronal vocal corollary discharge pathway in the hindbrain of a highly vocal species of fish. Neurons carrying the vocal corollary discharge are specifically adapted for the transmission of duration information, a predominant acoustic cue. The results reveal that vertebrates, like some insects, have a robust corollary discharge conveying call duration. Along with evidence for the influence of vocal duration on auditory encoding in mammals, these new findings suggest that linking vocal motor and corollary discharge pathways with pattern generating, call duration neurons is a shared network character across the animal kingdom. PMID:24285884

Chagnaud, Boris P; Bass, Andrew H

2013-11-27

351

25 CFR 163.24 - Duration of timber contracts.  

Code of Federal Regulations, 2011 CFR

... Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER GENERAL FORESTRY REGULATIONS Forest Management and Operations § 163.24 Duration of timber contracts. After the effective date of a forest product contract,...

2011-04-01

352

42 CFR 86.36 - Duration and continuation.  

Code of Federal Regulations, 2012 CFR

...SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES GRANTS FOR EDUCATION PROGRAMS IN OCCUPATIONAL SAFETY AND HEALTH Occupational Safety and Health Direct Traineeships § 86.36 Duration...

2012-10-01

353

43 CFR 3430.6-3 - Duration of leases.  

Code of Federal Regulations, 2013 CFR

43 Public Lands: Interior 2 2013-10-01... false Duration of leases. 3430.6-3 Section 3430.6-3 Public Lands: Interior Regulations...Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT...3000) NONCOMPETITIVE LEASES Preference Right...

2013-10-01

354

43 CFR 3120.2-1 - Duration of lease.  

Code of Federal Regulations, 2013 CFR

43 Public Lands: Interior 2 2013-10-01... false Duration of lease. 3120.2-1 Section 3120.2-1 Public Lands: Interior Regulations...Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT...3000) COMPETITIVE LEASES Competitive Leases...

2013-10-01

355

THE ASSOCIATION BETWEEN BATHING AND WEANING TRIAL DURATION  

PubMed Central

OBJECTIVE To describe patterns of bath care for patients who are weaning from prolonged mechanical ventilation (PMV) and to explore the association between bathing and weaning trial duration. METHODS Descriptive correlational study. Clinical records from 439 weaning trial days for 30 patients who required PMV were abstracted for bathing occurrences during weaning trials, within1-hour before a trial, and nocturnally. RESULTS Most baths occurred during weaning trials (30.8%) or at night (35.3%), and less frequently (16%) within 1-hour before a trial. No significant effects were found on trial duration for nocturnal bathing or bathing within 1-hour before a trial. Using random coefficient modeling, weaning duration was shown to be longer when bathing occurred during a weaning trial (p<.05), even when controlling for age, severity of illness, and days on bedrest. CONCLUSION Bathing occurred during nearly one-third of PMV weaning trials. Baths during PMV weaning trials were associated with longer weaning trial duration.

Sereika, Susan M.; Tate, Judith A.; DiVirgilio-Thomas, Dana; Hoffman, Leslie A.; Swigart, Valerie A.; Broyles, Lauren; Roesch, Tricia; Happ, Mary Beth

2010-01-01

356

Vocal Corollary Discharge Communicates Call Duration to Vertebrate Auditory System  

PubMed Central

Corollary discharge is essential to an animal's ability to filter self-generated from external stimuli. This includes acoustic communication, although direct demonstration of a corollary discharge that both conveys a vocal motor signal and informs the auditory system about the physical attributes of a self-generated vocalization has remained elusive for vertebrates. Here, we show the underlying synaptic activity of a neuronal vocal corollary discharge pathway in the hindbrain of a highly vocal species of fish. Neurons carrying the vocal corollary discharge are specifically adapted for the transmission of duration information, a predominant acoustic cue. The results reveal that vertebrates, like some insects, have a robust corollary discharge conveying call duration. Along with evidence for the influence of vocal duration on auditory encoding in mammals, these new findings suggest that linking vocal motor and corollary discharge pathways with pattern generating, call duration neurons is a shared network character across the animal kingdom.

2013-01-01

357

KIVA-I Extended Duration MHD Generator Development.  

National Technical Information Service (NTIS)

An extended duration magnetohydrodynamic (MHD) generator system was developed. This system consists of the MHD combustor, nozzle, generator channel, diffuser, high speed data acquisition system and high voltage converter. Two steady-state generator channe...

H. W. Hehn J. K. Lytle L. W. Buechler R. A. Nimmo R. V. Shanklin

1975-01-01

358

45 CFR 400.113 - Duration of eligibility.  

Code of Federal Regulations, 2013 CFR

...HUMAN SERVICES REFUGEE RESETTLEMENT PROGRAM Child Welfare Services § 400.113 Duration of eligibility...IV-B plan prescribes for the availability of child welfare services to any other child in the...

2013-10-01

359

42 CFR 61.38 - Duration of service fellowships.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Duration of service fellowships. 61.38 Section 61.38 Public Health...DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING FELLOWSHIPS Service Fellowships § 61.38...

2013-10-01

360

The Effects of Long-Duration Spaceflight on Postflight Terrestrial Locomotion  

NASA Technical Reports Server (NTRS)

Locomotion is a complex task requiring the coordinated integration of multiple sensorimotor subsystems. This coordination is exemplified by the precise control of segmental kinematics that allows smooth progression of movement in the face of changing environmental constraints. Exposure to the microgravity environment encountered during space flight induces adaptive modification in the central processing of sensory input to produce motor responses appropriate for the prevailing environment. This inflight adaptive change in sensorimotor function is inappropriate for movement control in 1-g and leads to postflight disturbances in terrestrial locomotor function. We have previously explored the effects of short-duration (7-16 days) space flight on the control of locomotion. The goal of the present set of studies was to investigate the effects of long-duration spaceflight (3-6 months) on the control of locomotion with particular emphasis on understanding how the multiple interacting systems are adaptively modified by prolonged microgravity exposure.

Bloomberg, J. J.; Mulavara, A. P.; McDonald, P. V.; Layne, C. S.; Merkle, L. A.; Cohen, H. S.; Kozlovskaya, I. B.

1999-01-01

361

Clinical parameters predicting survival duration after hepatectomy for intrahepatic cholangiocarcinoma  

PubMed Central

BACKGROUND: Currently, the most effective treatment for intrahepatic cholangiocarcinoma (ICC) is complete hepatic tumour excision. OBJECTIVE: To identify the clinical parameters associated with survival duration for ICC patients following hepatectomy, and to construct a mathematical model for predicting survival duration. METHODS: Demographic data and clinical variables for 102 patients diagnosed with ICC, who underwent exploratory laparotomy at a single centre from July 1998 to December 2000 and were followed for an average of 24 months, were collected in 2011. Patients were randomly assigned into training (n=76) and validation (n=26) groups. Univariate and multivariate analyses were performed to identify factors associated with posthepatectomy survival duration. RESULTS: Univariate analysis revealed that more than three lymph node metastases, a serum carbohydrate antigen 19-9 level >37 U/mL, stage IVa tumours, and intra- or perihepatic metastases were significantly associated with decreased survival duration. Curative resection was significantly associated with increased survival duration. A mathematical model incorporating parameters of age, sex, metastatic lymph node number, curative surgery, carbohydrate antigen 19-9 concentration, alpha-fetoprotein concentration, hepatitis B, TNM stage and tumour differentiation was constructed for predicting survival duration. For a survival duration of less than one year, the model exhibited 93.8% sensitivity, 92.3% total accuracy and a positive predictive value of 93.8%; for a survival duration of one to three years, the corresponding values were 80.0%, 69.2% and 57.1%, repsectively. CONCLUSIONS: The mathematical model presented in the current report should prove to be useful in the clinical setting for predicting the extent to which curative resection affects the survival of ICC patients, and for selecting optimal postoperative treatment strategies.

Jiang, Bei-ge; Ge, Rui-liang; Sun, Liang-liang; Zong, Ming; Wei, Gong-tian; Zhang, Yong-jie

2011-01-01

362

A long-duration propulsive lunar landing testbed  

Microsoft Academic Search

Affordable test articles for descent and landing are crucial for developing commercial lunar landing capability. To ensure successful lunar landing, flight software must be tested over mission-length durations on hardware exhibiting dynamics analogous to those of true flight articles. Energetic and structural constraints typically preclude affordable long- duration lander tests. This paper details a first-in-kind propulsive lunar lander testbed designed

Krishna Shankar; Kevin Peterson; Heather Jones; Justin Moidel; William Whittaker

2011-01-01

363

Strategies for crew selection for long duration missions  

NASA Technical Reports Server (NTRS)

Issues surrounding psychological reactions to long duration spaceflight are discussed with respect to the definition of criteria for selecting crewmembers for such expeditions. Two broad dimensions of personality and behavior are defined - Instrumentality including achievement orientation, leadership, and ability to perform under pressure and Expressivity encompassing interpersonal sensitivity and competence. A strategy for validating techniques to select in candidates with the optimum psychological profile to perform successfully on long duration missions is described.

Helmreich, Robert L.; Holland, Albert W.; Santy, Patricia A.; Rose, Robert M.; Mcfadden, Terry J.

1990-01-01

364

Predicting the Phytoextraction Duration to Remediate Heavy Metal Contaminated Soils  

Microsoft Academic Search

The applicability of phytoextraction to remediate soils contaminated with heavy metals (HMs) depends on, amongst others, the\\u000a duration before remediation is completed. The impact of changes in the HM content in soil occurring during remediation on\\u000a plant uptake has to be considered in order to obtain a reliable estimate of the phytoextraction duration. To simulate the\\u000a decrease in the HM

G. F. Koopmans; P. F. A. M. Römkens; J. Song; E. J. M. Temminghoff; J. Japenga

2007-01-01

365

Procedures used for assessment of stuttering frequency and stuttering duration.  

PubMed

Frequency of stuttered syllables and their durations were assessed using different procedures. The experiment examined overall syllable counts, counts of stuttered syllables and measures of stutter durations when they were made simultaneously or successively. Samples of speech with associated syllable, stuttered syllable and duration measurements of stuttering events were employed in reference transcriptions. Samples contained a minimum of 200 syllables. Ten participants assessed these samples for syllables, stuttered syllables and duration in an experiment. The responses of these participants were stored in alignment with the speech recordings for analysis. Performance was significantly more accurate (relative to transcriptions) for measures other than duration when the successive procedure was used as opposed to the simultaneous procedure. Although the successive method was more accurate, accuracy of stutter event identification was low for most participants. The procedure that allowed listeners to replay a speech sample and count the syllables, stuttered syllables and durations in three passes yielded more accurate syllable and stuttered syllable counts than procedures that required these judgments to be made in one pass. PMID:23848369

Jani, Leanne; Huckvale, Mark; Howell, Peter

2013-12-01

366

Sleep duration and survival percentiles across categories of physical activity.  

PubMed

The association between long sleep duration and death is not fully understood. Long sleep is associated with low physical activity, which is a strong predictor of death. Our aim was to investigate the association between sleep duration and death across categories of total physical activity in a large prospective cohort of Swedish men and women. We followed a population-based cohort of 70,973 participants (37,846 men and 33,127 women), aged 45-83 years, from January 1998 to December 2012. Sleep duration and physical activity levels were assessed through a questionnaire. We evaluated the association of interest in terms of mortality rates by estimating hazard ratios with Cox regression and in terms of survival by evaluating 15th survival percentile differences with Laplace regression. During 15 years of follow-up, we recorded 14,575 deaths (8,436 men and 6,139 women). We observed a significant interaction between sleep duration and physical activity in predicting death (P < 0.001). Long sleep duration (>8 hours) was associated with increased mortality risk (hazard ratio = 1.24; 95% confidence interval: 1.11, 1.39) and shorter survival (15th percentile difference = -20 months; 95% confidence interval: -30, -11) among only those with low physical activity. The association between long sleep duration and death might be partly explained by comorbidity with low physical activity. PMID:24264294

Bellavia, Andrea; Ĺkerstedt, Torbjörn; Bottai, Matteo; Wolk, Alicja; Orsini, Nicola

2014-02-15

367

Asymmetric processing of durational differences - Electrophysiological investigations in Bengali.  

PubMed

Duration is used contrastively in many languages to distinguish word meaning (e.g. in Bengali, [pata] 'leaf' vs. [pat:a] 'whereabouts'). While there is a large body of research on other contrasts in speech perception (e.g. vowel contrasts and consonantal place features), little work has been done on how durational information is used in speech processing. In non-linguistic studies of low-level processing, such as visual and non-linguistic acoustic pop-out tasks, an asymmetry is found where additional information is more readily detected than missing information. In this study, event-related potentials were recorded during two cross-modal auditory-visual semantic priming studies, where nonword mispronunciations of spoken prime words were created by changing the duration of a medial consonant (real word [dana] 'seed'>nonword (?)[dan:a]). N400 amplitudes showed an opposite asymmetric pattern of results, where increases in consonantal duration were tolerated and led to priming of the visual target, but decreases in consonantal duration were not accepted. This asymmetrical pattern of acceptability is attributed to the fact that a longer consonant includes all essential information for the recognition of the original word with a short medial consonant (a possible default category) and any additional information can be ignored. However, when a consonant is shortened, it lacks the required durational information to activate the word with the original long consonant. PMID:24726333

Roberts, Adam C; Kotzor, Sandra; Wetterlin, Allison; Lahiri, Aditi

2014-05-01

368

Sleep duration and incidence of colorectal cancer in postmenopausal women  

PubMed Central

Background: Sleep duration is dependent on circadian rhythm that controls a variety of key cellular functions. Circadian disruption has been implicated in colorectal tumorigenesis in experimental studies. We prospectively examined the association between sleep duration and risk of colorectal cancer (CRC). Methods: In the Women's Health Initiative Observational Study, 75?828 postmenopausal women reported habitual sleep duration at baseline 1993–1998. We used Cox proportional hazards regression model to estimate the hazard ratio (HR) of CRC and its associated 95% confidence interval (CI). Results: We ascertained 851 incident cases of CRC through 2010, with an average 11.3 years of follow-up. Compared with 7?h of sleep, the HRs were 1.36 (95% CI 1.06–1.74) and 1.47 (95% CI 1.10–1.96) for short (?5?h) and long (?9?h) sleep duration, respectively, after adjusting for age, ethnicity, fatigue, hormone replacement therapy (HRT), physical activity, and waist to hip ratio. The association was modified by the use of HRT (P-interaction=0.03). Conclusion: Both extreme short and long sleep durations were associated with a moderate increase in the risk of CRC in postmenopausal women. Sleep duration may be a novel, independent, and potentially modifiable risk factor for CRC.

Jiao, L; Duan, Z; Sangi-Haghpeykar, H; Hale, L; White, D L; El-Serag, H B

2013-01-01

369

Depth-Duration Frequency of Precipitation for Oklahoma  

USGS Publications Warehouse

A regional frequency analysis was conducted to estimate the depth-duration frequency of precipitation for 12 durations in Oklahoma (15, 30, and 60 minutes; 1, 2, 3, 6, 12, and 24 hours; and 1, 3, and 7 days). Seven selected frequencies, expressed as recurrence intervals, were investigated (2, 5, 10, 25, 50, 100, and 500 years). L-moment statistics were used to summarize depth-duration data and to determine the appropriate statistical distributions. Three different rain-gage networks provided the data (15minute, 1-hour, and 1-day). The 60-minute, and 1-hour; and the 24-hour, and 1-day durations were analyzed separately. Data were used from rain-gage stations with at least 10-years of record and within Oklahoma or about 50 kilometers into bordering states. Precipitation annual maxima (depths) were determined from the data for 110 15-minute, 141 hourly, and 413 daily stations. The L-moment statistics for depths for all durations were calculated for each station using unbiased L-mo-ment estimators for the mean, L-scale, L-coefficient of variation, L-skew, and L-kur-tosis. The relation between L-skew and L-kurtosis (L-moment ratio diagram) and goodness-of-fit measures were used to select the frequency distributions. The three-parameter generalized logistic distribution was selected to model the frequencies of 15-, 30-, and 60-minute annual maxima; and the three-parameter generalized extreme-value distribution was selected to model the frequencies of 1-hour to 7-day annual maxima. The mean for each station and duration was corrected for the bias associated with fixed interval recording of precipitation amounts. The L-scale and spatially averaged L-skew statistics were used to compute the location, scale, and shape parameters of the selected distribution for each station and duration. The three parameters were used to calculate the depth-duration-frequency relations for each station. The precipitation depths for selected frequencies were contoured from weighted depth surfaces to produce maps from which the precipitation depth-duration-frequency curve for selected storm durations can be determined for any site in Oklahoma.

Tortorelli, Robert L.; Rea, Alan; Asquith, William H.

1999-01-01

370

Duration of gestation in pregnant dogs carrying cloned fetuses.  

PubMed

The aim of this study was to investigate gestation duration and the physiologic characteristics of pregnant dogs bearing cloned fetuses, especially in the prepartum period. A retrospective study was performed to compare gestation duration in females pregnant with cloned (somatic cell nuclear transfer) fetuses (cloned group) with those bearing noncloned fetuses (control group), and effects of litter size, birth weight, and breed of somatic cell donors on gestation duration in the cloned group were evaluated. Clinical delivery onset signs associated with serum progesterone concentration and rectal temperature were also compared in both groups. The gestation duration calculated from day of ovulation was significantly longer in the cloned (62.8 ± 0.3 days) versus the control group (60.9 ± 0.5 days; P < 0.001). There was a negative correlation between litter size and gestation duration including both groups (r = -0.59; P < 0.01), but there were no differences between birth weights or breed of cell donors and gestation duration in the cloned group. Even though the basal rectal temperature in the prepartum period was not different between control and cloned groups (36.9 ± 0.1 °C and 37.2 ± 0.1 °C, respectively), serum progesterone concentration on delivery day was significantly higher in the cloned group (2.2 ± 0.4 ng/ml) compared with the control group (0.5 ± 0.1 ng/ml; P < 0.05). The longer gestation duration of pregnant dogs bearing cloned fetuses might be because of the smaller litter size in this group. Also, the weaker drop in serum progesterone levels in the prepartum period in cloned dog pregnancies indicates that the parturition signaling process might be altered resulting in longer gestation periods. PMID:23174777

Kim, Min Jung; Oh, Hyun Ju; Park, Jung Eun; Kim, Geon A; Park, Eun Jung; Jo, Young Kwang; Lee, Byeong Chun

2013-01-15

371

An Electroencephalographic Investigation of the Filled-Duration Illusion  

PubMed Central

The study investigated how the brain activity changed when participants were engaged in a temporal production task known as the “filled-duration illusion.” Twelve right-handed participants were asked to memorize and reproduce the duration of time intervals (600 or 800?ms) bounded by two flashes. Random trials contained auditory stimuli in the form of three 20?ms sounds between the flashes. In one session, the participants were asked to ignore the presence of the sounds, and in the other, they were instructed to pay attention to sounds. The behavioral results showed that duration reproduction was clearly affected by the presence of the sounds and the duration of time intervals. The filled-duration illusion occurred when there were sounds; the participants overestimated the interval in the 600-ms interval condition with sounds. On the other hand, the participants underestimated the 800-ms interval condition without sounds. During the presentation of the interval to be encoded, the contingent negative variation (CNV) appeared around the prefrontal scalp site, and P300 appeared around the parieto-central scalp site. The CNV grew larger when the intervals contained the sounds, whereas the P300 grew larger when the intervals were 800?ms and did not contain the sounds. During the reproduction of the interval to be presented, the Bereitschaftspotential (BP) appeared over the fronto-central scalp site from 1000?ms before the participants’ response. The BP could refer to the decision making process associated with the duration reproduction. The occurrence of three event-related potentials (ERPs), the P300, CNV, and BP, suggests that the fronto-parietal area, together with supplementary motor area (SMA), is associated with timing and time perception, and magnitude of these potentials is modulted by the “filled-duration illusion”.

Mitsudo, Takako; Gagnon, Caroline; Takeichi, Hiroshige; Grondin, Simon

2011-01-01

372

Human responses to bright light of different durations  

PubMed Central

Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18 ± 3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (<3 lux), and were then randomized for exposure to a bright light pulse (?10,000 lux) of 0.2 h, 1.0 h, 2.5 h or 4.0 h duration during a 4.5 h controlled-posture episode centred in a 16 h wake episode. After another 8 h sleep episode, participants completed a second circadian phase assessment. Phase shifts were calculated from the difference in the clock time of the dim light melatonin onset (DLMO) between the initial and final phase assessments. Exposure to varying durations of bright light reset the circadian pacemaker in a dose-dependent, non-linear manner. Per minute of exposure, the 0.2 h duration was over 5 times more effective at phase delaying the circadian pacemaker (1.07 ± 0.36 h) as compared with the 4.0 h duration (2.65 ± 0.24 h). Acute melatonin suppression and subjective sleepiness also had a dose-dependent response to light exposure duration. These results provide strong evidence for a non-linear resetting response of the human circadian pacemaker to light duration.

Chang, Anne-Marie; Santhi, Nayantara; St Hilaire, Melissa; Gronfier, Claude; Bradstreet, Dayna S; Duffy, Jeanne F; Lockley, Steven W; Kronauer, Richard E; Czeisler, Charles A

2012-01-01

373

Earth-Space Links and Fade-Duration Statistics  

NASA Technical Reports Server (NTRS)

In recent years, fade-duration statistics have been the subject of several experimental investigations. A good knowledge of the fade-duration distribution is important for the assessment of a satellite communication system's channel dynamics: What is a typical link outage duration? How often do link outages exceeding a given duration occur? Unfortunately there is yet no model that can universally answer the above questions. The available field measurements mainly come from temperate climatic zones and only from a few sites. Furthermore, the available statistics are also limited in the choice of frequency and path elevation angle. Yet, much can be learned from the available information. For example, we now know that the fade-duration distribution is approximately lognormal. Under certain conditions, we can even determine the median and other percentiles of the distribution. This paper reviews the available data obtained by several experimenters in different parts of the world. Areas of emphasis are mobile and fixed satellite links. Fades in mobile links are due to roadside-tree shadowing, whereas fades in fixed links are due to rain attenuation.

Davarian, Faramaz

1996-01-01

374

Earth-space links and fade-duration statistics  

NASA Technical Reports Server (NTRS)

In recent years, fade-duration statistics have been the subject of several experimental investigations. A good knowledge of the fade-duration distribution is important for the assessment of a satellite communication system's channel dynamics: What is a typical link outage duration? How often do link outages exceeding a given duration occur? Unfortunately there is yet no model that can universally answer the above questions. The available field measurements mainly come from temperate climatic zones and only from a few sites. Furthermore, the available statistics are also limited in the choice of frequency and path elevation angle. Yet, much can be learned from the available information. For example, we now know that the fade-duration distribution is approximately lognormal. Under certain conditions, we can even determine the median and other percentiles of the distribution. This paper reviews the available data obtained by several experimenters in different parts of the world. Areas of emphasis are mobile and fixed satellite links. Fades in mobile links are due to roadside-tree shadowing, whereas fades in fixed links are due to rain attenuation.

Davarian, Faramaz

1995-01-01

375

Building a Shared Definitional Model of Long Duration Human Spaceflight  

NASA Technical Reports Server (NTRS)

In 1956, on the eve of human space travel Strughold first proposed a simple classification of the present and future stages of manned flight that identified key factors, risks and developmental stages for the evolutionary journey ahead. As we look to optimize the potential of the ISS as a gateway to new destinations, we need a current shared working definitional model of long duration human space flight to help guide our path. Initial search of formal and grey literature augmented by liaison with subject matter experts. Search strategy focused on both the use of term long duration mission and long duration spaceflight, and also broader related current and historical definitions and classification models of spaceflight. The related sea and air travel literature was also subsequently explored with a view to identifying analogous models or classification systems. There are multiple different definitions and classification systems for spaceflight including phase and type of mission, craft and payload and related risk management models. However the frequently used concepts of long duration mission and long duration spaceflight are infrequently operationally defined by authors, and no commonly referenced classical or gold standard definition or model of these terms emerged from the search. The categorization (Cat) system for sailing was found to be of potential analogous utility, with its focus on understanding the need for crew and craft autonomy at various levels of potential adversity and inability to gain outside support or return to a safe location, due to factors of time, distance and location.

Orr, M.; Whitmire, A.; Sandoval, L.; Leveton, L.; Arias, D.

2011-01-01

376

Duration of Lactation and Maternal Metabolism at 3 Years Postpartum  

PubMed Central

Abstract Objective Lactation has been associated with reduced risk of type 2 diabetes and the metabolic syndrome in mothers. We examined the relation between breastfeeding duration and metabolic markers at 3 years postpartum. Methods We used linear regression to relate duration of lactation to maternal glucose and lipid metabolism, inflammatory markers, and anthropometry at 3 years postpartum among 570 participants with 3-year blood samples (175 fasting) in Project Viva, a cohort study of mothers and children. Results Among the participants, 88% had initiated breastfeeding, and 26% had breastfed ?12 months. In multivariate analyses, we observed no consistent trends relating duration of lactation to maternal metabolism at 3 years postpartum. Women who exclusively breastfed for >6 months had lower postpartum weight retention at 3 years than women with shorter durations of exclusive breastfeeding (multivariate adjusted predicted mean ?0.5, ?3.6–2.6?kg vs. 4.8, 2.0–7.6?kg for those who never exclusively breastfed, partial F p?=?0.03). Conclusions In this prospective cohort study, we did not observe a dose-response relationship between duration of lactation and metabolic risk at 3 years postpartum.

Kleinman, Ken; Gillman, Matthew W.; Rifas-Shiman, Sheryl L.; Gunderson, Erica P.; Rich-Edwards, Janet

2010-01-01

377

Effectiveness and duration of intramuscular antimotion sickness medications  

NASA Technical Reports Server (NTRS)

Motion sickness inhibits gastric motility, making the oral route ineffective for medications. The intramuscular route is an effective alternative. The rotating chair was used to produce the M 111 level of motion sickness on the Graybiel Symptom Scale. The intramuscular medications given 30 minutes before rotation were compared with placebo (saline, 1 mL) for effectiveness and duration in increasing the number of tolerated head movements. Average placebo number of head movements was 294. Promethazine 25 mg increased head movements by 78% (P < .05), with a duration of 12 hours. Scopolamine 0.2 mg increased head movements by 91% (P < .05), with a duration of 4 hours. The effect of caffeine 250 mg and ephedrine 25 mg was not significant. When combined with scopolamine, ephedrine produced an 32% additive effect. Scopolamine 0.08 mg, 0.1 mg, and 0.2 mg and also promethazine 12.5 mg and 25 mg were significant (P < .05). Promethazine appears to be the drug of choice for intramuscular use because of a longer duration and a high level of effectiveness. Scopolamine was of high effectiveness, but had a duration of 4 hours. It was eight times as potent by the intramuscular as by the oral route.

Wood, C. D.; Stewart, J. J.; Wood, M. J.; Mims, M.

1992-01-01

378

Driver sensitivity to brake pulse duration and magnitude.  

PubMed

Adaptive cruise control (ACC) requires that the driver intervene in situations that exceed the capability of ACC. A brake pulse might provide a particularly compatible means of alerting the driver to situations in which the acceleration authority of the ACC has been exceeded. This study examined the sensitivity of the driver to brake pulses of five different amplitudes (0.01-0.025 g) and five different durations (50-800 ms). Drivers were sensitive to accelerations as low as 0.015 g. Pulse duration interacted with pulse amplitude, such that moderate duration pulses were more detectable than long and short duration pulses at intermediate levels of pulse amplitude. A power function with an exponent of 1.0 accounted for 99% of the variance in drivers' sensitivity to pulse amplitude; however, a power function with an exponent of 0.23 accounted for only 70% of the variance in drivers' sensitivity to pulse duration. These results can help designers create ACC algorithms and develop brake pulse warnings. PMID:17457744

Lee, J D; McGehee, D V; Brown, T L; Nakamoto, J

2007-06-01

379

ECG diagnosis: The effect of ionized serum calcium levels on electrocardiogram.  

PubMed

High and low levels of ionized serum calcium concentration can produce characteristic changes on the electrocardiogram. These changes are almost entirely limited to the duration of the ST segment, with no change in the QRS complexes or T waves. High ionized serum calcium shortens the ST segment, and low ionized serum calcium prolongs the ST segment. Two common clinical scenarios are presented. PMID:24626084

Gardner, Jonathan D; Calkins, Joe B; Garrison, Glen E

2014-01-01

380

Aerosol-induced signal in sunshine duration records: A review of evidences  

NASA Astrophysics Data System (ADS)

Aerosols play a complex and crucial role in the Earth's radiation budget, by enhancing the absorption and scattering of incoming solar radiation. Consequently, knowledge of the interannual and decadal changes of the atmospheric turbidity induced by aerosols is fundamental for a better understanding of the climate variability and change since pre-industrial times. However, there is a little knowledge regarding changes in aerosol concentrations in the atmosphere on decadal time scales, especially before 1980s, when both ground-based platforms (spectrophotometers) and satellite-borne measurements were available. Nevertheless, sunshine duration observations may be affected by changes in atmospheric aerosol loading, therefore they may provide an adequate proxy measurement for turbidity from the late 19th century up to present. This work reviews publications reporting the suitability of the sunshine duration records measured by Campbell-Stokes instruments to detect changes in atmospheric turbidity, with special emphasis on decadal time scales. In addition, some possible directions for future research are also suggested, particularly pointing out that analyses based on sunshine duration measurements could be extended worldwide since the 1950s due to the availability of records; for some regions, these data are available since as far as the late 19th century.

Sanchez-Romero, Alejandro; Sanchez-Lorenzo, Arturo; Azorin-Molina, Cesar; Calbó, Josep; González, Josep-Abel

2013-04-01

381

New method development in prehistoric stone tool research: Evaluating use duration and data analysis protocols.  

PubMed

Lithic microwear is a research field of prehistoric stone tool (lithic) analysis that has been developed with the aim to identify how stone tools were used. It has been shown that laser scanning confocal microscopy has the potential to be a useful quantitative tool in the study of prehistoric stone tool function. In this paper, two important lines of inquiry are investigated: (1) whether the texture of worn surfaces is constant under varying durations of tool use, and (2) the development of rapid objective data analysis protocols. This study reports on the attempt to further develop these areas of study and results in a better understanding of the complexities underlying the development of flexible analytical algorithms for surface analysis. The results show that when sampling is optimised, surface texture may be linked to contact material type, independent of use duration. Further research is needed to validate this finding and test an expanded range of contact materials. The use of automated analytical protocols has shown promise but is only reliable if sampling location and scale are defined. Results suggest that the sampling protocol reports on the degree of worn surface invasiveness, complicating the ability to investigate duration related textural characterisation. PMID:25041833

Evans, Adrian A; Macdonald, Danielle A; Giusca, Claudiu L; Leach, Richard K

2014-10-01

382

Long Duration Testing of Type C Thermocouples at 1500 °C  

SciTech Connect

Experience with Type C thermocouples operating for long periods in the 1400 to 1600 °C temperature range indicate that significant decalibration occurs, often leading to expensive downtime and material waste. As part of an effort to understand the mechanisms causing drift in these thermocouples, the Idaho National Laboratory conducted a long duration test at 1500 °C containing eight Type C thermocouples. As report in this document, results from this long duration test were adversely affected due to oxygen ingress. Nevertheless, results provide key insights about the impact of precipitate formation on thermoelectric response. Post-test examinations indicate that thermocouple signal was not adversely impacted by the precipitates detected after 1,000 hours of heating at 1,500 °C and suggest that the signal would not have been adversely impacted by these precipitates for longer durations (if oxygen ingress had not occurred in this test).

Joy L. Rempe; Darrell L. Knudson; J. E. Daw; S. C. Wilkins

2008-04-01

383

Hypothesis testing as an approach to the analysis of complex tachycardias--an illustrative case of a preexcitation variant.  

PubMed

The correct elucidation of the electrophysiological substrate and mechanism(s) responsible for a complex arrhythmia requires a systematic approach to the analysis of the electrophysiological data. One approach calls for the formulation of a set of hypotheses that could explain the data obtained during the study. The hypotheses are then tested for compatibility with phenomena observed and the one that agrees with the majority of the findings would represent the most tenable explanation. We present the case of a young girl with a wide QRS complex tachycardia and a history of ventricular preexcitation that illustrates this approach. The complexities were resolved only after intraoperative analysis and surgical ablation of a right-sided accessory pathway with decremental properties, and provides further insight into our understanding of the nodoventricular Mahaim fiber. PMID:1721133

Teo, W S; Yee, R; Klein, G J; Guiraudon, G M; Leitch, J W

1991-10-01

384

Secondhand Smoke Exposure, Restless Sleep, and Sleep Duration in Adolescents  

PubMed Central

Purpose. To examine whether secondhand smoke (SHS) exposure is associated with restless sleep and/or nighttime sleep duration among adolescents. Methods. Data were analyzed from 1,592 adolescents who completed an internet-delivered survey as part of the British Columbia Adolescent Substance Use Survey cohort study. Ordinal logistic and linear regression models were used to examine associations between frequency of SHS exposure in the past month and frequency of restless sleep and nighttime sleep duration, respectively. Results. SHS exposure was significantly positively associated with restless sleep and significantly negatively associated with sleep duration. In fully adjusted models, compared with students who reported never being exposed to SHS in the past month, students who reported a low, medium, or high frequency of SHS exposure were 1.53, 1.76, and 2.51 times as likely, respectively, to report more frequent restless sleep (OR = 1.53, 95% CI 1.08–2.16; OR = 1.76, 95% CI 1.22–2.53; OR = 2.51, 95% CI 1.59–3.98). With regard to sleep duration, as frequency of SHS exposure increased by one category, nighttime sleep duration during the week and weekend decreased by 4 minutes (B = ?0.06, 95% CI = ?0.01– ? 0.11) and 6 minutes (B = ?0.09, 95% CI = ?0.03– ? 0.14), respectively. Conclusions. This study suggests that frequency of SHS exposure has a significant dose-response relationship with restless sleep and sleep duration in adolescents.

Bottorff, Joan L.

2014-01-01

385

Comparison of Postural Recovery Following Short and Long Duration Spaceflights  

NASA Technical Reports Server (NTRS)

INTRODUCTION: Post-flight postural ataxia reflects adaptive changes to vestibulo-spinal reflexes and control strategies adopted for movement in weightlessness. Quantitative measures obtained during computerized dynamic posturography (CDP) from US and Russian programs provide insight into the effect of spaceflight duration in terms of both the initial decrements and recovery of postural stability. METHODS: CDP was obtained on 117 crewmembers following Shuttle flights lasting 4-17 days, and on 64 crewmembers following long-duration missions lasting 48-380 days. Although the number and timing of sessions varied, the goal was to characterize postural recovery pooling similar measures from different research and flight medicine programs. This report focuses on eyes closed, head erect conditions with either a fixed or sway-referenced base of support. A smaller subset of subjects repeated the sway-referenced condition while making pitch head movements (+/- 20deg at 0.33Hz). Equilibrium scores were derived from peak-to-peak anterior-posterior sway. Fall probability was modeled using Bayesian statistical methods to estimate parameters of a logit function. RESULTS: The standard Romberg condition was the least sensitive. Longer duration flights led to larger decrements in stability with sway-reference support during the first 1-2 days, although the timecourse of recovery was similar across flight duration with head erect. Head movements led to increased incidence of falls during the first week, with a significantly longer recovery following long duration flights. CONCLUSIONS: The diagnostic assessment of postural instability, and differences in the timecourse of postural recovery between short and long flight durations, are more pronounced during unstable support conditions requiring active head movements.

Wood, S. J.; Fiedler, J.; Taylor, L. C.; Kozlovskaya, I.; Black, F. O.; Paloski, W. H.

2010-01-01

386

Self-Reported Sleep Duration and Weight-Control Strategies Among US High School Students  

PubMed Central

Study Objective: To determine if self-reported sleep duration was associated with weight-control behaviors among US high school students. Design: National Youth Risk Behavior Survey. Setting: United States, 2007. Participants: US high school students (N = 12,087). Measurements: Students were asked if they had engaged in several weight-control behaviors during the 30 days before the survey to lose or maintain weight. Self-reported sleep duration categories included very short (? 5 h), short (6 or 7 h), referent moderate (8 or 9 h), and long (? 10 h). Sex-specific logistic regression analyses with race/ethnicity, grade, and body mass index category as covariates were conducted using SUDAAN to account for complex study design. Results: Approximately half the students reported short sleep duration (51.8% of males and 54.3% of females), whereas very short sleep durations were reported by another 14.8% of males and 16.9% of females. Among males, very short sleepers were significantly (P < 0.05) more likely than moderate sleepers to report dieting (36.3% versus 26.1%), fasting (14.2% versus 4.3%), and purging (4.3% versus 1.1%) to lose or maintain weight during the 30 days before the survey. Among females, the respective very short, short, and moderate sleepers varied (P < 0.05) in dieting (59.9%, 55.0%, and 47.5% respectively), fasting (28.3%, 15.2%, and 10.3%, respectively), and taking diet pills (13.3%, 6.8%, and 4.3%, respectively). Prevalence of purging was significantly higher only for very short sleepers (12.3%, 6.0%, and 3.9%, respectively). Conclusion: Self-reported short sleep duration was associated with dieting and three unhealthy weight-control behaviors in this population. If our findings are confirmed, intervention studies should be conducted to examine the effect of educational interventions. Citation: Wheaton AG; Perry GS; Chapman DP; Croft JB. Self-reported sleep duration and weight-control strategies among US high school students. SLEEP 2013;36(8):1139-1145.

Wheaton, Anne G.; Perry, Geraldine S.; Chapman, Daniel P.; Croft, Janet B.

2013-01-01

387

Building a Shared Definitional Model of Long Duration Human Spaceflight  

NASA Technical Reports Server (NTRS)

Objective: To establish the need for a shared definitional model of long duration human spaceflight, that would provide a framework and vision to facilitate communication, research and practice In 1956, on the eve of human space travel, Hubertus Strughold first proposed a "simple classification of the present and future stages of manned flight" that identified key factors, risks and developmental stages for the evolutionary journey ahead. As we look to new destinations, we need a current shared working definitional model of long duration human space flight to help guide our path. Here we describe our preliminary findings and outline potential approaches for the future development of a definition and broader classification system

Arias, Diana; Orr, Martin; Whitmire, Alexandra; Leveton, Lauren; Sandoval, Luis

2012-01-01

388

Crew productivity issues in long-duration space flight  

NASA Technical Reports Server (NTRS)

Considerable evidence suggests the importance of teamwork, coordination, and conflict resolution to the performance and survival of isolated, confined groups in high-technology environments. With the advent of long-duration space flight, group-related issues of crew functioning will take on added significance. This paper discusses the influence of crew roles, status, leadership, and norms on the performance of small, confined groups, and offers guidelines and suggestions regarding organizational design, crew selection, training, and team building for crew productivity and social well-being in long-duration spaceflight.

Nicholas, John M.; Foushee, H. Clayton; Ulschak, Francis L.

1988-01-01

389

Increasing point-count duration increases standard error  

USGS Publications Warehouse

We examined data from point counts of varying duration in bottomland forests of west Tennessee and the Mississippi Alluvial Valley to determine if counting interval influenced sampling efficiency. Estimates of standard error increased as point count duration increased both for cumulative number of individuals and species in both locations. Although point counts appear to yield data with standard errors proportional to means, a square root transformation of the data may stabilize the variance. Using long (>10 min) point counts may reduce sample size and increase sampling error, both of which diminish statistical power and thereby the ability to detect meaningful changes in avian populations.

Smith, W.P.; Twedt, D.J.; Hamel, P.B.; Ford, R.P.; Wiedenfeld, D.A.; Cooper, R.J.

1998-01-01

390

Discharge-Duration-Frequency Surfaces: An Intergrating Approach  

NASA Astrophysics Data System (ADS)

Discharge-Duration-Frequency curves are a concise form of capturing the information of hydrological-engineering interest from marginal and joint probability distribution functions of a river-discharge stochastic process. They are nomograms, obtained from constant-T sections of Q(T,D) surfaces. In the present work, we propose the direct construction and use of Q(D,P) surfaces that allow for an easy swap between maxima and minima of discharges of different durations. They are hereby comprehensive in scope and appropriate for engineering use, which we illustrate by an example from the Villa de Fuentes (Mexico) hydrological gauging station.

Bâ, Khalidou; Díaz-Delgado, Carlos; Carsteanu, Alin

2014-05-01

391

Duration of liquid water habitats on early Mars  

NASA Astrophysics Data System (ADS)

The duration of ice-covered lakes after the initial freezing of the early Mars is presently estimated via a climate model whose critical parameter is the existence of peak seasonal temperatures above freezing, and in which the variability of insolation is included. Under conditions in which meltwater was supplied by an ice source, it is found that water habitats could have been maintained under relatively thin ice sheets for as many as 700 million years after the onset of below-freezing global temperatures. The duration of such habitats on the early Mars therefore exceeds the upper limit of the time envisioned for the emergence of aquatic life on earth.

McKay, C. P.; Davis, W. L.

1991-04-01

392

Cognitive Assessment in Long-Duration Space Flight  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the development and use of a tool for assessing spaceflight cognitive ability in astronauts. This tool. the Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) has been used to provide ISS flight surgeons with an objective clinical tool to monitor the astronauts cognitive status during long-duration space flight and allow immediate feedback to the astronaut. Its use is medically required for all long-duration missions and it contains a battery of five cognitive assessment subtests that are scheduled monthly and compared against the individual preflight baseline.

Kane, Robert; Seaton, Kimberly; Sipes, Walter

2011-01-01

393

XeCl master oscillator with 300-ns pulse duration  

NASA Astrophysics Data System (ADS)

Development of a long-pulse master oscillator with pulse duration of 300 ns (FWHM) is reported. The oscillator is made on the base of a long-pulse spark preionized XeCl-laser pumped by a self-sustained discharge using a double- discharge circuit. The pre-pulse is formed by a generator with an inductive energy storage and a semiconductor opening switch. The laser produces up to 1,5 J in pulse with total duration up to 450 ns.

Baksht, Evgenii H.; Losev, Valery F.; Panchenko, Alexei N.; Panchenko, Yury N.; Tarasenko, Victor F.

2002-03-01

394

A comparison of sunshine duration records from the Campbell-Stokes sunshine recorder and CSD3 sunshine duration sensor  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to compare daily sunshine duration data measured using a Campbell-Stokes sunshine recorder (CS) and a CSD3 sunshine duration sensor (AUTO) as well as to attempt to explain discrepancies between the two data sets. The paper is based on heliographic data and cloudiness observations for 2007-2012. All the data come from the research station of the Jagiellonian University located in Krakow, Poland. Both instruments tend to produce similar sunshine duration data; however, the electronic sensor tends to show more sunshine duration than the CS. The difference may amount to several hours a day, especially on days with maximum solar radiation. The CSD3 sensor is twice as sensitive as the CS and reacts quickly to solar radiation. This is especially true for the first hour following sunrise, the last hour before sunset and when the Sun's disc becomes visible for short periods of time due to changes in cloudiness. However, there are days when the CSD3 registers less sunshine duration (up to an hour) than the CS. This happens with Cumulus clouds in the sky, which tend to pass the Sun's disc very quickly. The CSD3 sensor does not register sunshine in the presence of thick Altostratus and Cirrostratus clouds due to the relative lack of direct radiation. The sunshine recorder, on the other hand, registers this low level of sunshine.

Matuszko, Dorota

2014-02-01

395

Right Hemispheric Contributions to Fine Auditory Temporal Discriminations: High-Density Electrical Mapping of the Duration Mismatch Negativity (MMN)  

PubMed Central

That language processing is primarily a function of the left hemisphere has led to the supposition that auditory temporal discrimination is particularly well-tuned in the left hemisphere, since speech discrimination is thought to rely heavily on the registration of temporal transitions. However, physiological data have not consistently supported this view. Rather, functional imaging studies often show equally strong, if not stronger, contributions from the right hemisphere during temporal processing tasks, suggesting a more complex underlying neural substrate. The mismatch negativity (MMN) component of the human auditory evoked-potential provides a sensitive metric of duration processing in human auditory cortex and lateralization of MMN can be readily assayed when sufficiently dense electrode arrays are employed. Here, the sensitivity of the left and right auditory cortex for temporal processing was measured by recording the MMN to small duration deviants presented to either the left or right ear. We found that duration deviants differing by just 15% (i.e. rare 115?ms tones presented in a stream of 100?ms tones) elicited a significant MMN for tones presented to the left ear (biasing the right hemisphere). However, deviants presented to the right ear elicited no detectable MMN for this separation. Further, participants detected significantly more duration deviants and committed fewer false alarms for tones presented to the left ear during a subsequent psychophysical testing session. In contrast to the prevalent model, these results point to equivalent if not greater right hemisphere contributions to temporal processing of small duration changes.

De Sanctis, Pierfilippo; Molholm, Sophie; Shpaner, Marina; Ritter, Walter; Foxe, John J.

2009-01-01

396

Cyclostratigraphic and magnetostratigraphic constraints on the duration of the CAMP  

Microsoft Academic Search

The duration of what may be the largest known flood basalt, the Central Atlantic Magmatic Province (CAMP), has major implications for the magmatic processes intimately related to one of the largest known continental rift provinces formed just antecedent to the break-up of central Pangea. While the reported scatter in radiometric dates from the CAMP has been decreasing in recent years

P. E. Olsen; D. V. Kent

2001-01-01

397

Duration of spermatogenesis in the bullfrog (Lithobates catesbeianus).  

PubMed

The bullfrog (Lithobates catesbeianus) has substantial economic importance and has also been used as an experimental model for biological studies in the fields of pharmacology, medicine, and reproductive biology, especially studies addressing gametogenesis. However, there is a lack of comprehensive information in the literature regarding testis structure and function in this amphibian. The main objective of the current study was to estimate the duration of the various phases of spermatogenesis in this vertebrate. Sixteen sexually mature bullfrogs received an intracoelomic administration of tritiated thymidine. Testes were analyzed at various times between 1h and 33 d after administration to detect the most advanced germ cell types labeled at each interval, as well as labeled preleptotene spermatocytes, which presumably originated from spermatogonial stem cells. The duration of the spermatogonial, spermatocytic, and spermiogenic phases of spermatogenesis in the bullfrog were approximately 18, 14, and 8 d, respectively. Thus, the total duration of the spermatogenesis process from early spermatogonia through to spermatozoa was 40 d in this species, similar to that of most previously investigated mammalian species. To our knowledge, this is the first reliable report on the duration of the full spermatogenic process in any amphibian species. These findings will be very useful for tracking the pace of germ cells in studies involving spermatogonial transplantation in lower vertebrates. PMID:19683337

Segatelli, T M; Batlouni, S R; França, L R

2009-10-15

398

Markov Switching Model of GNP Growth with Duration Dependence.  

National Technical Information Service (NTIS)

We use a regime-switching model of real GNP growth to examine the duration dependence of business cycles. The model extends Hamilton (1989) and Durland and McCurdy (1994) and is estimated using both the postwar NIPA data and the secular data constructed b...

P. Lam

1997-01-01

399

Temporal Context in Concurrent Chains: I. Terminal-Link Duration  

ERIC Educational Resources Information Center

Two experiments are reported in which the ratio of the average times spent in the terminal and initial links ("Tt/Ti") in concurrent chains was varied. In Experiment 1, pigeons responded in a three-component procedure in which terminal-link variable-interval schedules were in constant ratio, but their average duration increased across components…

Grace, Randolph C.

2004-01-01

400

The effects of odor and body posture on perceived duration.  

PubMed

This study reports an examination of the internal clock model, according to which subjective time duration is influenced by attention and arousal state. In a time production task, we examine the hypothesis that an arousing odor and an upright body posture affect perceived duration. The experimental task was performed while participants were exposed to an odor and either sitting upright (arousing condition) or lying down in a relaxing chair (relaxing condition). They were allocated to one of three experimental odor conditions: rosemary (arousing condition), peppermint (relaxing condition), and no odor (control condition). The predicted effects of the odors were not borne out by the results. Self-reported arousal (SRA) and pleasure (PL) states were measured before, during (after each body posture condition) and postexperimentally. Heart rate (HR) and skin conductance were measured before and during the experiment. As expected, odor had an effect on perceived duration. When participants were exposed to rosemary odor, they produced significantly shorter time intervals than in the no odor condition. This effect, however, could not be explained by increased arousal. There was no effect of body posture on perceived duration, even though body posture did induce arousal. The results do not support the proposed arousal mechanism of the internal clock model. PMID:24567718

Schreuder, Eliane; Hoeksma, Marco R; Smeets, Monique A M; Semin, Gün R

2014-01-01

401

Long Duration Space Missions: Human Subsystem Risks and Requirements  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the human health and performance risks associated with long duration space flight beyond low earth orbit. The contents include: 1) Human Research Program; 2) Human Subsystem Risks; 3) Human Exploration Framework Team (HEFT) Architecture Elements; 4) Potentially Unacceptable Risks -1; 5) Potentially Unacceptable Risks-2; and 6) Major Mission Drivers of Risk.

Kundrot, Criag E.

2011-01-01

402

Ecohydrological model of flow duration curves and annual minima  

Microsoft Academic Search

To address streamflow variability in river basins, Botter et al. (2007a) recently provided an analytical solution for the seasonal probability distribution function of daily streamflows on the basis of a stochastic description of soil moisture dynamics at basin scales. In this paper the above model is extended to the annual timescale to derive analytical expressions for the long-term flow duration

Gianluca Botter; Stefano Zanardo; Amilcare Porporato; Ignacio Rodriguez-Iturbe; Andrea Rinaldo

2008-01-01

403

A Method for modeling long-duration joint motion  

Microsoft Academic Search

Musculoskeletal disorders of the upper extremities, in particular the wrist and the shoulder, have become the largest class of injury in workers' compensation claims in the United States. Monitoring the development, progression, and treatment of degenerative orthopedic diseases, such as carpal tunnel and shoulder impingement syndrome, may be more effective when joint motions are assessed over long durations in real-world

M. J. Qadri; D. R. Peterson

2011-01-01

404

Short Sleep Duration and Incident Coronary Artery Calcification  

Microsoft Academic Search

Context Coronary artery calcification is a subclinical predictor of coronary heart dis- ease. Recent studies have found that sleep duration is correlated with established risk factors for calcification including glucose regulation, blood pressure, sex, age, educa- tion, and body mass index. Objective To determine whether objective and subjective measures of sleep dura- tion and quality are associated with incidence of

Christopher Ryan King; Kristen L. Knutson; Paul J. Rathouz; Steve Sidney; Kiang Liu; Diane S. Lauderdale

405

MULTIFREQUENCY DATA EXTRAPOLATION THROUGH MINIMIZATION OF TIME SIGNAL DURATION  

Microsoft Academic Search

Method of signal extrapolation in frequency domain for improvement of resolution in time domain is proposed. The main idea of this method is use of concept of duration of signal for formulation of non-energy constraints, when there is a priori information about finiteness of signal support in time domain. Unlike traditional extrapolation techniques no strict model of extrapolated data is

O. Antropov; V. Borulko; O. Drobakhin; S. Vovk

406

Superresolution via extrapolation with constraints on signal duration  

Microsoft Academic Search

Method of signal extrapolation in frequency domain for improvement of resolution in time domain is proposed. The main idea of this method is use of concept of duration of signal through formulation of non-energy constraints, when there is a priori information about finiteness of signal support in time domain. Unlike traditional extrapolation techniques no strict model of extrapolated data is

O. Antropov; V. Borulko; O. Drobakhin; S. Vovk

2008-01-01

407

CRISP: A Computational Model of Fixation Durations in Scene Viewing  

ERIC Educational Resources Information Center

Eye-movement control during scene viewing can be represented as a series of individual decisions about where and when to move the eyes. While substantial behavioral and computational research has been devoted to investigating the placement of fixations in scenes, relatively little is known about the mechanisms that control fixation durations.…

Nuthmann, Antje; Smith, Tim J.; Engbert, Ralf; Henderson, John M.

2010-01-01

408

The Effect of Congenital Deafness on Duration Judgment  

ERIC Educational Resources Information Center

Objective: Congenital deafness provides the opportunity to study how atypical sensory and language experiences affect different aspects of information processing, e.g., time perception. Methods: Using two methods of temporal estimation, reproduction (Exp. 1) and production (Exp. 2), the effect of deafness on duration judgment was investigated…

Kowalska, Joanna; Szelag, Elzbieta

2006-01-01

409

Mediating Civil War Settlements and the Duration of Peace  

Microsoft Academic Search

In this article, we examine the impact of international mediation attempts during civil war on the duration of peace once the war has ended. We include several aspects of the mediation attempt in our theoretical framework and our empirical tests, but we also control for other characteristics of the conflict and the country. While studies often find that decisive victories

Mehmet Gurses; Nicolas Rost; Patrick McLeod

2008-01-01

410

Perceived duration as a function of auditory stimulus frequency  

Microsoft Academic Search

Ss made absolute magnitude estimations of durations ranging from 8-250 sec. Auditory clicks were broadcast during each trial at frequencies ranging from 0-10 clicks\\/sec. Magnitude estimations were found to be an increasing function of click frequency from 0-1.50\\/sec, thereafter declining slightly. The magnitude of this \\

Austin Jones; Marilyn Maclean

1966-01-01

411

Duration of the pharmacodynamic interaction between pancuronium and mivacurium.  

PubMed

The aim of this study was to determine for how long the duration of action of increments of mivacurium can be influenced by previous pancuronium administration. Fifteen patients, ASA I or II, undergoing general anaesthesia for major abdominal surgery were investigated. The post-tetanic count (PTC) was measured at the adductor pollicis muscle. Pancuronium 0.1 mg kg-1 was injected first. At recovery of the 10th response of the PTC (PTC10), a second dose of pancuronium was injected (0.02 mg kg-1). On recovery to PTC10, a bolus of mivacurium (0.04 mg kg-1) was given and regularly repeated at recovery of PTC10 until the end of surgery. The mean duration of the second dose of pancuronium was 53 min (SD 13 min) and of the first dose of mivacurium, 66 min (SD 14 min) (P < 0.01). The duration of action of further mivacurium boluses decreased significantly until the fifth dose. It took 222 minutes (95% confidence interval 190, 253 min) after the second pancuronium dose before the duration of action of mivacurium returned to normal values and became constant and predictable. PMID:9813534

Beaussier, M; Deriaz, H; De Traverse, A; Abdelhalim, Z; Lienhart, A

1998-08-01

412

The Effects of Sound Duration on Newborns' Head Orientation.  

ERIC Educational Resources Information Center

Two experiments assessed the importance of sound duration for eliciting head orientation responses from newborn infants. Results suggest that newborns' head orientation response may reflect a motor program that is initiated by auditory input and then executed in a similar fashion regardless of further stimulation. (Author/AS)

Clarkson, Marsha G.; And Others

1985-01-01

413

The effects of odor and body posture on perceived duration  

PubMed Central

This study reports an examination of the internal clock model, according to which subjective time duration is influenced by attention and arousal state. In a time production task, we examine the hypothesis that an arousing odor and an upright body posture affect perceived duration. The experimental task was performed while participants were exposed to an odor and either sitting upright (arousing condition) or lying down in a relaxing chair (relaxing condition). They were allocated to one of three experimental odor conditions: rosemary (arousing condition), peppermint (relaxing condition), and no odor (control condition). The predicted effects of the odors were not borne out by the results. Self-reported arousal (SRA) and pleasure (PL) states were measured before, during (after each body posture condition) and postexperimentally. Heart rate (HR) and skin conductance were measured before and during the experiment. As expected, odor had an effect on perceived duration. When participants were exposed to rosemary odor, they produced significantly shorter time intervals than in the no odor condition. This effect, however, could not be explained by increased arousal. There was no effect of body posture on perceived duration, even though body posture did induce arousal. The results do not support the proposed arousal mechanism of the internal clock model.

Schreuder, Eliane; Hoeksma, Marco R.; Smeets, Monique A. M.; Semin, Gun R.

2013-01-01

414

How Do Changes in Speed Affect the Perception of Duration?  

ERIC Educational Resources Information Center

Six experiments investigated how changes in stimulus speed influence subjective duration. Participants saw rotating or translating shapes in three conditions: constant speed, accelerating motion, and decelerating motion. The distance moved and average speed were the same in all three conditions. In temporal judgment tasks, the constant-speed…

Matthews, William J.

2011-01-01

415

Estimating weather impact on the duration of construction activities  

Microsoft Academic Search

Weather conditions can have an adverse impact on the duration and cost of construction activities. Quantifying this impact is, clearly, valuable to contractors for preparing realistic schedules, cost estimates, and reliable bids. Productivity loss due to the impact of weather on construction activities can be either partial or complete; partial loss is generally attributed to reduced labor productivity and complete

Osama Moselhi; Daji Gong; Khaled El-Rayes

1997-01-01

416

Global solar radiation estimation using sunshine duration in Spain  

Microsoft Academic Search

Several equations were employed to estimate global solar radiation from sunshine hours for 16 meteorological stations in Spain, using only the relative duration of sunshine. These equations included the original Angström–Prescott linear regression and modified functions (quadratic, third degree, logarithmic and exponential functions). Estimated values were compared with measured values in terms of the coefficient of determination, standard error of

J. Almorox; C. Hontoria

2004-01-01

417

Work Duration and Work Scheduling for Hospital Doctors  

Microsoft Academic Search

In spite of their high responsibility for patients health work practiced schedules and work duration of medical doctors widely offend legal limits. This situation is a conse- quence of putting economic pressure on a formerly charity-based work organization. Actual court decisions enforce a complete rearrangement of clinical shift scheduling, to some extent with questionable consequences. Scheduling of clinical shifts must

Matthias GÖBEL; Martin FRANCK; Wolfgang FRIESDORF

418

Practitioner Empathy and the Duration of the Common Cold  

PubMed Central

Objective To assess the relationship of empathy in medical consultations to subsequent cold outcomes. Methods 350 subjects, ?12 years of age received either a standard or enhanced physician visit as part of a randomized controlled trial. The patient-scored Consultation and Relational Empathy (CARE) questionnaire assessed practitioner-patient interaction, especially empathy. Cold severity and duration were assessed from twice daily symptom reports. Nasal wash was performed to measure the immune cytokine IL-8. Results 84 individuals reported perfect (score of 50) CARE scores. They tended to be older with less education, but reported similar health status, quality of life, and levels of optimism. In those with perfect CARE scores, cold duration was shorter (mean 7.10 days vs. 8.01 days, p=0.032), and there was a trend towards reduced severity (mean AUC 240.40 vs. 284.49, p=0.118). After accounting for possible confounding variables, cold severity and duration were significantly lower in those reporting perfect CARE scores (p=0.037 and p=0.017 respectively). In these models, a perfect score also correlates with a larger increase in IL-8 levels (p=0.015). Conclusions Clinician empathy, as perceived by patients with the common cold, significantly predicts subsequent duration and severity of illness and is associated with immune system changes.

Rakel, David P.; Hoeft, Theresa J.; Barrett, Bruce P.; Chewning, Betty A.; Craig, Benjamin M.; Niu, Min

2009-01-01

419

Sampling duration effects on centre of pressure summary measures  

Microsoft Academic Search

The purpose of the present study was to examine the effect of sample duration on the magnitude and reliability of centre of pressure (COP) summary measures commonly used to characterize the control of upright stance. COP was recorded from 49 participants who stood quietly during three consecutive 120 s trials. Each record was subdivided into 15, 30, 60 and 120

Mark G Carpenter; James S Frank; David A Winter; Gerhard W Peysar

2001-01-01

420

Active shielding for long duration interplanetary manned missions  

Microsoft Academic Search

For long duration interplanetary manned missions the protection of astronauts from cosmic radiation is an unavoidable problem that has been considered by many space agencies. In Europe, during 2002–2004, the European Space Agency supported two research programs on this thematic: one was the constitution of a dedicated study group (on the thematic ‘Shielding from cosmic radiation for interplanetary missions: active

Piero Spillantini

2010-01-01

421

Duration, Satisfaction, and Perceived Effectiveness of Cross- Cultural Counseling.  

ERIC Educational Resources Information Center

Examined relationship between cultural dissimilarity and duration, satisfaction, and perceived effectiveness of counseling in treatment dyads that varied race of counselor and client. Results indicated White counselors provided fewer sessions than non-White counselors and non-White clients expressed less satisfaction with counseling, regardless of…

Neimeyer, Greg J.; Gonzales, Michael

1983-01-01

422

Duration, Satisfaction, and Perceived Effectiveness of Cross-Cultural Counseling.  

ERIC Educational Resources Information Center

It is generally acknowledged that racial groups differ in their values, beliefs and behaviors as well as counseling needs, but evidence is mixed as to the effects of racial differences in the counseling process. A sample of 70 clients participated in a study to examine the differences in the duration, satisfaction, and effectiveness resulting from…

Neimeyer, Greg J.; Gonzales, Michael

423

Sleep Duration, Nap Habits, and Mortality in Older Persons  

PubMed Central

Objective: To examine the effect of nighttime sleep duration on mortality and the effect modification of daytime napping on the relationship between nighttime sleep duration and mortality in older persons. Design: Prospective survey with 20-yr mortality follow-up. Setting: The Cross-Sectional and Longitudinal Aging Study, a multidimensional assessment of a stratified random sample of the older Jewish population in Israel conducted between 1989-1992. Participants: There were 1,166 self-respondent, community-dwelling participants age 75-94 yr (mean, 83.40, standard deviation, 5.30). Measurements: Nighttime sleep duration, napping, functioning (activities of daily living, instrumental activities of daily living, Orientation Memory Concentration Test), health, and mortality. Results: Duration of nighttime sleep of more than 9 hr was significantly related to increased mortality in comparison with sleeping 7-9 hr (hazard ratio [HR] = 1.31, P < 0.01) after adjusting for demographic, health, and function variables, whereas for short nighttime sleep of fewer than 7 hr mortality did not differ from that of 7-9 hr of sleep. For those who nap, sleeping more than 9 hr per night significantly increased mortality risk (HR = 1.385, P < 0.05) and shorter nighttime sleep reduced mortality significantly in the unadjusted model (HR = 0.71, P < 0.001) but only approached significance in the fully adjusted model (HR = 0.82, P = 0.054). For those who do not or sometimes nap, a short amount of sleep appears to be harmful up to age 84 yr and may be protective thereafter (HR = 1.51, confidence interval [CI] = 1.13-2.02, P < 0.01; HR = 0.76, CI = 0.49-1.17, in the fully adjusted model, respectively). Conclusions: The findings are novel in demonstrating the protective effect of short nighttime sleep duration in individuals who take daily naps and suggest that the examination of the effect of sleep needs to take into account sleep duration per 24 hr, rather than daytime napping or nighttime sleep per se. Citation: Cohen-Mansfield J; Perach R. Sleep duration, nap habits, and mortality in older persons. SLEEP 2012;35(7):1003–1009.

Cohen-Mansfield, Jiska; Perach, Rotem

2012-01-01

424

Shortened Sleep Duration does not Predict Obesity in Adolescents  

PubMed Central

Obesity continues to be a major public health issue. In adolescents, there are limited studies on the relationship between obesity and sleep duration. We hypothesied that average sleep duration of less than 6 hours in adolescents was associated with obesity. Data was from the National Longitudinal Study of Adolescent Health (ADD Health); survey of 90,000 youths, ages 12 – 18 years; surveyed in several waves. The sample population for our study was 13,568. Weighted multiple logistic regression was used to identify relationship between obesity at Wave II and sleep duration, having adjusted for skipping breakfast ? 2/week; race, gender, parental income, TV ? 2hrs/day, depression, and obesity at Wave I. At Wave I, mean age 15.96±0.11 yrs; mean sleep hours 7.91±0.04. 10.6% and 11.2% of adolescents were obese at Waves I and II, respectively. Adjusted analyses suggest that effect of shortened sleep duration in Wave I was not significantly predictive of obesity in Wave II (p<0.218).Longitudinally, depression and TV ? 2hrs/day at Wave I was associated with higher risk of obesity at Wave II in adjusted analyses. Depressed adolescents were almost twice as likely to be obese (OR=1.84, 95% CI=1.25–2.72); adolescents who watched TV ? 2hrs/day were 37% more likely to be obese (OR=1.37, 95% CI=1.09–1.72).Environmental factors including TV ? 2hrs/day and depression were significantly associated with obesity; shortened sleep duration was not. Future longitudinal studies in adolescents are needed to determine whether timing of television watching directly influences sleep patterns, and ultimately obesity.

Calamaro, Christina J.; Park, Sunhee; Mason, Thornton B. A.; Marcus, Carole L.; Weaver, Terri E.; Pack, Allan; Ratcliffe, Sarah J.

2010-01-01

425

Effects of Internal Clock and Memory Disorders on Duration Reproductions and Duration Productions in Patients with Parkinson's Disease  

ERIC Educational Resources Information Center

Patients with Parkinson's disease (PD) exhibit deficits in perceptual and motor timing as well as impairments in memory and attentional processes that are related to dysfunction of dopaminergic systems in the basal ganglia. The aim of the present study was to assess the relationships existing between impaired duration judgments and defective…

Perbal, S.; Deweer, B.; Pillon, B.; Vidailhet, M.; Dubois, B.; Pouthas, V.

2005-01-01

426

Hydroperiods of created and natural vernal pools in central Ohio: A comparison of depth and duration of inundation  

Microsoft Academic Search

Water levels were recorded weekly from six natural vernal pools and 10 created vernal pools at two forested wetland complexes\\u000a in central Ohio. Vernal pool median water depth and duration of inundation were significantly greater at the created vernal\\u000a pools than at the natural vernal pools (? = 0.05, P < 0.05). The average period of inundation for created pools was 309 ± 32 days, compared with

Debra L. Gamble; William J. Mitsch

2009-01-01

427

Shape complexity  

Microsoft Academic Search

The complexity of 3D shapes that are represented in digital form and processed in CAD\\/CAM\\/CAE, entertainment, biomedical, and other applications has increased considerably. Much research was focused on coping with or on reducing shape complexity. But, what exactly is shape complexity? We discuss several complexity measures and the corresponding complexity reduction techniques. Algebraic complexity measures the degree of polynomials needed

Jarek Rossignac

2005-01-01

428

Extended duration orbiter study: CO2 removal and water recovery  

NASA Technical Reports Server (NTRS)

Two electrochemical depolarized carbon dioxide concentrator subsystems were evaluated against baseline lithium hydroxide for (1) the baseline orbiter when expanded to accommodate a crew of seven (mission option one), (2) an extended duration orbiter with a power extension package to reduce fuel cell expendables (mission option two), and (3) an extended duration orbiter with a full capability power module to eliminate fuel cell expendables (mission option three). The electrochemical depolarized carbon dioxide concentrator was also compared to the solid amine regenerable carbon dioxide removal concept. Water recovery is not required for Mission Option One since sufficient water is generated by the fuel cells. The vapor compression distillation subsystem was evaluated for mission option two and three only. Weight savings attainable using the vapor compression distillation subsystem for water recovery versus on-board water storage were determined. Combined carbon dioxide removal and water recovery was evaluated to determine the effect on regenerable carbon dioxide removal subsystem selection.

Marshall, R. D.; Ellis, G. S.; Schubert, F. H.; Wynveen, R. A.

1979-01-01

429

Space mechanisms needs for future NASA long duration space missions  

NASA Technical Reports Server (NTRS)

Future NASA long duration missions will require high performance, reliable, long lived mechanical moving systems. In order to develop these systems, high technology components, such as bearings, gears, seals, lubricants, etc., will need to be utilized. There has been concern in the NASA community that the current technology level in these mechanical component/tribology areas may not be adequate to meet the goals of long duration NASA mission such as Space Exploration Initiative (SEI). To resolve this concern, NASA-Lewis sent a questionnaire to government and industry workers (who have been involved in space mechanism research, design, and implementation) to ask their opinion if the current space mechanisms technology (mechanical components/tribology) is adequate to meet future NASA Mission needs and goals. In addition, a working group consisting of members from each NASA Center, DoD, and DOE was established to study the technology status. The results of the survey and conclusions of the working group are summarized.

Fusaro, Robert L.

1991-01-01

430

Extended Duration Orbiter (EDO) Improved Waste Collection System (IWCS)  

NASA Technical Reports Server (NTRS)

This high angle overall view shows the top side components of the Extended Duration Orbiter (EDO) Waste Collection System (WCS) scheduled to fly aboard NASA's Endeavour, Orbiter Vehicle (OV) 105, for the STS-54 mission. Detailed Test Objective 662, Extended duration orbiter WCS evaluation, will verify the design of the new EDO WCS under microgravity conditions for a prolonged period. OV-105 has been modified with additional structures in the waste management compartment (WMC) and additional avionics to support/restrain the EDO WCS. Among the advantages the new IWCS is hoped to have over the currect WCS are greater dependability, better hygiene, virtually unlimited capacity, and more efficient preparation between shuttle missions. Unlike the previous WCS, the improved version will not have to be removed from the spacecraft to be readied for the next flight. The WCS was documented in JSC's Crew Systems Laboratory Bldg 7.

1992-01-01

431

Extended Duration Orbiter (EDO) Improved Waste Collection System (IWCS)  

NASA Technical Reports Server (NTRS)

This overall front view shows the Extended Duration Orbiter (EDO) Waste Collection System (WCS) scheduled to fly aboard NASA's Endeavour, Orbiter Vehicle (OV) 105, for the STS-54 mission. Detailed Test Objective 662, Extended duration orbiter WCS evaluation, will verify the design of the new EDO WCS under microgravity conditions for a prolonged period. OV-105 has been modified with additional structures in the waste management compartment (WMC) and additional avionics to support/restrain the EDO WCS. Among the advantages the new IWCS is hoped to have over the currect WCS are greater dependability, better hygiene, virtually unlimited capacity, and more efficient preparation between shuttle missions. Unlike the previous WCS, the improved version will not have to be removed from the spacecraft to be readied for the next flight. The WCS was documented in JSC's Crew Systems Laboratory Bldg 7.

1992-01-01

432

SHORT-DURATION LENSING EVENTS. II. EXPECTATIONS AND PROTOCOLS  

SciTech Connect

Ongoing microlensing observations by OGLE and MOA regularly identify lensing events with Einstein diameter crossing time, {tau}{sub E}, of 16 or fewer days. Events with estimated values of {tau}{sub E} of one to two days have been detected. Short-duration events tend to be generated by low-mass lenses or by lenses with high transverse velocities. We compute the expected rates, demonstrate the expected ranges of parameters for lenses of different mass, and develop a protocol for observing and modeling short-duration events. Relatively minor additions to the procedures presently used will increase the rate of planet discovery, and also discover or place limits on the population of high-speed dim stars and stellar remnants in the vicinity of the Sun.

Di Stefano, Rosanne [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-08-01

433

Habitability and Performance Issues for Long Duration Space Flights  

NASA Technical Reports Server (NTRS)

Advancing technology, coupled with the desire to explore space has resulted in increasingly longer manned space missions. Although the Long Duration Space Flights (LDSF) have provided a considerable amount of scientific research on human ability to function in extreme environments, findings indicate long duration missions take a toll on the individual, both physiologically and psychologically. These physiological and psychological issues manifest themselves in performance decrements; and could lead to serious errors endangering the mission, spacecraft and crew. The purpose of this paper is to document existing knowledge of the effects of LDSF on performance, habitability, and workload and to identify and assess potential tools designed to address these decrements as well as propose an implementation plan to address the habitability, performance and workload issues.

Whitmore, Mihriban; McQuilkin, Meredith L.; Woolford, Barbara J.

1997-01-01

434

Pulse duration spectra and measurements for laser scanning microscope systems  

Microsoft Academic Search

Computer-controlled, repeatable ultra-short pulse lasers and a broad wavelength range autocorrelator have opened up practical spectral investigations of the group delay dispersion in laser scanning microscope systems. The laser output pulse duration was measured via intensity-based (two-photon absorption) autocorrelation and the laser spectral bandwidth was measured via spinning spectrometer. The separate measurements provided the ~0.39 timebandwidth product for two different

David L. Wokosin

2005-01-01

435

The Effect of Unemployment Compensation on Unemployment Duration in Germany  

Microsoft Academic Search

In West Germany during the 1980s, law changes cut the level of unemployment compensation for the unemployed without children and extended the duration of unemployment insurance for unemployed aged over forty-one. Analysis of these changes using the German Socioeconomic Panel shows that transitions from unemployment for those under forty-nine were particularly responsive to extensions of unemployment insurance. The implied elasticity

Jennifer Hunt

1995-01-01

436

Inductively stabilized, long pulse duration transverse discharge apparatus  

DOEpatents

An inductively stabilized, long pulse duration transverse discharge apparatus. The use of a segmented electrode where each segment is attached to an inductive element permits high-energy, high-efficiency, long pulsed laser outputs to be obtained. The apparatus has been demonstrated with rare gas halide lasing media. Orders of magnitude increase in pulse repetition frequency are obtained in lasing devices that do not utilize gas flow.

Sze, R.C.

1983-09-01

437

Progress toward a microsecond duration, repetitively pulsed, intense- ion beam  

SciTech Connect

A number of intense ion beams applications are emerging requiring repetitive high-average-power beams. These applications include ablative deposition of thin films, rapid melt and resolidification for surface property enhancement, advanced diagnostic neutral beams for the next generation of Tokamaks, and intense pulsed-neutron sources. We are developing a 200-250 keV, 15 kA, 1 {mu}s duration, 1-30 Hz intense ion beam accelerator to address these applications.

Davis, H.A.; Olson, J.C.; Reass, W.A. [Los Alamos National Lab., NM (United States); Coates, D.M.; Hunt, J.W.; Schleinitz, H.M. [Du Pont de Nemours (E.I.) and Co., Wilmington, DE (United States). Central Research and Development Dept.; Lovberg, R.H. [California Univ., San Diego, La Jolla, CA (United States); Greenly, J.B. [Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies

1996-07-01

438

Duration of breast feeding and language ability in middle childhood.  

PubMed

There is controversy over whether increased breast-feeding duration has long-term benefits for language development. The current study examined whether the positive associations of breast feeding on language ability at age 5 years in the Western Australian Pregnancy (Raine) Cohort, were still present at age 10 years. The Raine Study is a longitudinal study of 2868 liveborn children recruited at approximately 18 weeks gestation. Breast-feeding data were based upon information prospectively collected during infancy, and were summarised according to four categories of breast-feeding duration: (1) never breast-fed, (2) breast-fed predominantly for <4 months, (3) breast-fed predominantly for 4-6 months, and (4) breast-fed predominantly for >6 months. Language ability was assessed in 1195 children at the 10 year follow-up (mean age = 10.58 years; standard deviation = 0.19) using the Peabody Picture Vocabulary Test - Revised (PPVT-R), which is based around a mean of 100 and a standard deviation of 15. Associations between breast-feeding duration and PPVT-R scores were assessed before and after adjustment for a range of sociodemographic, obstetric and psychosocial covariates. Analysis of variance revealed a strong positive association between the duration of predominant breast feeding and PPVT-R at age 10 years. A multivariable linear regression analysis adjusted for covariates and found that children who were predominantly breast-fed for >6 months had a mean PPVT-R score that was 4.04 points higher than children who were never breast-fed. This compared with an increase of 3.56 points at age 5 years. Breast feeding for longer periods in early life has a positive and statistically-independent effect on language development in middle childhood. PMID:21133968

Whitehouse, Andrew J O; Robinson, Monique; Li, Jianghong; Oddy, Wendy H

2011-01-01

439

Cultural and Gender Issues in Long-Duration Flights  

NASA Technical Reports Server (NTRS)

Session TA5 includes short reports concerning: (1) Psychological Issues During Long-Duration International Space Missions; (2) Psychosocial Issues in Crew Selection: Finding the Right Mix of the Right Stuff; (3) Culture, Gender and Mission Accomplishment: Operational Experience; (4) Interpersonal Tension in Multicultural Crews; (5) Personality and Coping in Extreme Environments; and (6) Application of Expedition and Polar Work Group Findings for Enhancing Performance in Space.

1997-01-01

440

Average outage duration of multihop communication systems with regenerative relays  

Microsoft Academic Search

Closed-form expressions for the average outage duration (AOD) of multihop regenerative communication systems over generalized fading channels are presented. Both noise-limited and interference-limited systems are studied. To show the usefulness of the presented expressions, some specific fading scenarios are considered. In addition, some numerical examples of interest comparing direct versus relayed transmission and studying the effect of increasing the number

Lin Yang; Mazen O. Hasna; Mohamed-slim Alouini

2005-01-01

441

TDR Using Autocorrelation and Varying-Duration Pulses  

NASA Technical Reports Server (NTRS)

In an alternative to a prior technique of time-domain-reflectometry (TDR) in which very short excitation pulses are used, the pulses have very short rise and fall times and the pulse duration is varied continuously between a minimum and a maximum value. In both the present and prior techniques, the basic idea is to (1) measure the times between the generation of excitation pulses and the reception of reflections of the pulses as indications of the locations of one or more defects along a cable and (2) measure the amplitudes of the reflections as indication of the magnitudes of the defects. In general, an excitation pulse has a duration T. Each leading and trailing edge of an excitation pulse generates a reflection from a defect, so that a unique pair of reflections is associated with each defect. In the present alternative technique, the processing of the measured reflection signal includes computation of the autocorrelation function R(tau) identical with fx(t)x(t-tau)dt where t is time, x(t) is the measured reflection signal at time t, and taus is the correlation interval. The integration is performed over a measurement time interval short enough to enable identification and location of a defect within the corresponding spatial interval along the cable. Typically, where there is a defect, R(tau) exhibits a negative peak having maximum magnitude for tau in the vicinity of T. This peak can be used as a means of identifying a leading-edge/trailing-edge reflection pair. For a given spatial interval, measurements are made and R(tau) computed, as described above, for pulse durations T ranging from the minimum to the maximum value. The advantage of doing this is that the effective signal-to-noise ratio may be significantly increased over that attainable by use of a fixed pulse duration T.

Lucena, Angel; Mullinex, Pam; Huang, PoTien; Santiago, Josephine; Mata, Carlos; Zavala, Carlos; Lane, John

2008-01-01

442

Consequences of shiftworking on sleep duration, sleepiness, and sleep attacks.  

PubMed

Rotating shift and permanent night work arrangements are known to compromise sleep. This study examined the effects of work schedule on sleep duration, excessive sleepiness, sleep attacks, driving, and domestic/professional accidents. A representative sample of the general population of the state of New York--3,345 individuals > or = 18 yrs of age--was interviewed by telephone regarding their sleep and psychiatric and organic disorders. Multivariate models were applied to derive odds ratios (OR) after adjustment for age, sex, physical illness, mental disorders, obstructive sleep apnea, and sleep duration. On average (+/-SE), workers slept 6.7 +/- 1.5 h, but 40% slept < 6.5 h/main sleep episode. Short-sleep duration (< 6 h) was strongly associated with fixed night (OR: 1.7) and day-evening-night shiftwork arrangement (OR: 1.9). Some 20% of the workers manifested excessive sleepiness in situations requiring high attention, and it was associated with the fixed night (OR: 3.3) and day-evening-night work arrangements (OR: 1.5). Overall, 5% of the workers reported sleep attacks; however, they occurred three-times more frequently in the fixed night (15.3%) than other work arrangements (OR: 3.2). Driving accidents during the previous 12 months were reported by 3.6% of the workers and were associated with fixed night (OR: 3.9) and day-evening-night (OR: 2.1) work schedules. The findings of this study indicate that working outside the regular daytime hours was strongly associated with shorter sleep duration, sleepiness, and driving accident risk. Night work is the most disrupting, as it is associated with insufficient sleep during the designated rest span and excessive sleepiness and sleep attacks during the span of activity, with an associated consequence being increased driving accident risk. PMID:20524802

Ohayon, Maurice M; Smolensky, Michael H; Roth, Thomas

2010-05-01

443

Radiation-shielding requirements on long-duration space missions  

Microsoft Academic Search

An analysis of radiation shielding requirements on long duration space missions is presented. The report finds the principal radiation hazards to be galactic cosmic radiation (cosmic rays) and radiation from solar flares. Galactic cosmic radiation is a continuous source of radiation delivering a dose equivalent to the blood-forming organs varying from 20 REM\\/year to 50 REM\\/year over the 11-year solar

J. R. Letaw; S. Clearwater

1986-01-01

444

Racial disparities in short sleep duration by occupation and industry.  

PubMed

Short sleep duration, which is associated with increased morbidity and mortality, has been shown to vary by occupation and industry, but few studies have investigated differences between black and white populations. By using data from a nationally representative sample of US adult short sleepers (n = 41,088) in the National Health Interview Survey in 2004-2011, we estimated prevalence ratios for short sleep duration in blacks compared with whites for each of 8 industry categories by using adjusted Poisson regression models with robust variance. Participants' mean age was 47 years; 50% were women and 13% were black. Blacks were more likely to report short sleep duration than whites (37% vs. 28%), and the black-white disparity was widest among those who held professional occupations. Adjusted short sleep duration was more prevalent in blacks than whites in the following industry categories: finance/information/real estate (prevalence ratio (PR) = 1.44, 95% confidence interval (CI): 1.30, 1.59); professional/administrative/management (PR = 1.30, 95% CI: 1.18, 1.44)