Standard Deviation Of Time Intervals Research Articles

Pressure-Sensor-Based Sleep Status and Quality Evaluation System

Sleep quality evaluation is a major approach to clinical diagnosis of different types of sleep andmental disturbances.How to render it possible for test subjects to complete sleep status detection and quality assessment in a natural environment is what this paper mainly highlights. Clinically, sleep disturbances are analyzed by the so-called Polysomnography (PSG). However, due to limitations in space and high cost, as well as the fact that test subjects must wear various physiological detection equipment during the test, the collected signal is susceptible to interference due to uncomfortable sensations. As such it usually does not reflect the realistic situation of the subject. For this reason,we propose in this paper a pressure-sensor-based smart mattress to realize sleep status detection and quality evaluation. Regarding sleep posture recognition, a proposed convolutional neural network (CNN) model in conjunction with a pressure distribution image formed by the pressure sensing matrix are applied. With respect to assessing the subjects’ time in bed, a support vectormachine (SVM) is used to determine sitting or lying postures, and further recognize the actual time in bed. As for sleep quality assessment, Fuzzy inference is adopted in this paper base on a set of four predefined sleep parameters. Compared with some of prior arts, the proposed systemdoes not require the test subjects to wear any equipment, and as such the subjects can complete the test in a natural environment. Experimental results show that the accuracy of the proposed SVM classifier for differentiating sitting and lying posture and that of CNN model for the recognition of four different sleep postures can be up to 99.986% and 96.987%, respectively. With the proposed model, precise sleep parameters, including time in bed, number of times of bed-leaving, number of times of body movements all night, standard deviation of time interval between body movements, and sleep posture can be provided. Moreover, the system does not use devices such as microphones or surveillance cameras to collect the data of the test subjects; thus, there is no concern about infringing the privacy of the subjects. It is believed that the system will be of considerable help and serve as an aid to clinical diagnosis of sleep disturbance.

Subclinical left ventricular dysfunction in men under androgen deprivation therapy for prostate cancer, revealed by speckle‐tracking‐derived parameters, repolarization, and myocardial injury markers

ObjectiveTo analyze global left ventricular longitudinal strain (GLS), mechanical dispersion (MD), electrocardiographic repolarization, and myocardial injury markers changes during androgen deprivation therapy (ADT) and subsequent hypogonadism in men with advanced prostate cancer.MethodsWe included 31 patients 69.7 ± 7.3 years old, in sinus rhythm, with stable cardiac conditions and evaluated them by echocardiography, electrocardiography, and blood sampling for high sensitivity cardiac troponin I (hs‐cTnI), and N‐terminal pro‐brain natriuretic peptide (NTproBNP), at ADT initiation (M0) and after 6 months of treatment (M1). Peak longitudinal strain by speckle‐tracking echocardiography was assessed in 17 left ventricular segments and averaged to GLS. Standard deviation of time intervals from the start of Q/R on electrocardiogram to peak longitudinal strain in the 17 segments (MDSD), and the difference between the longest and shortest time‐to‐peak strain intervals (MDdelta) were calculated as indices of MD. Fridericia corrected electrocardiographic repolarization parameters were analyzed as follows: QT interval (QTc), mean and maximum values of Tpeak‐Tend interval (Tpe), and Tpe/QT ratio, Tpe dispersion (Tped).ResultsSignificant impairments of the following parameters were registered between M0 and M1: GLS (%) (−16.93 ± 3.89; −14.43 ± 3.57, P < .001), MDSD (ms) (77.4 ± 21.4; 89 ± 27, P = .004), MDdelta (ms) (225.3 ± 78.3; 259.9 ± 108.4, P = .02), QTc (ms) (458.8 ± 43.4; 485.6 ± 45.1, P = .01), maxTpe/QT (0.246 ± 0.04; 0.268 ± 0.04, P = .01), maxTpe (ms) (105.4 ± 23.2; 119.5 ± 26.4 P = .01), meanTpe (ms) (83.3 ± 16.8; 90.7 ± 19.3, P = .02), and hs‐cTnI (ng/mL) (4.6 ± 5.4; 5.4 ± 6.4, P = .01). Mean serum testosterone level at M1 was 0.1 ± 0.13 ng/mL. The patients’ clinical cardiological status remained stable during follow‐up.ConclusionsADT and subsequent hypogonadism induce subclinical alterations in GLS, MD, electrocardiographic repolarization parameters, and hs‐cTnI during the first 6 months of treatment.

Evaluation of the effects of aerobic exercise in the aqueous environment on heart rate variability by using Poincare plot nonlinear method

Background and Aim: Heart rate variability used as a non-invasive method to investigate the effect of aerobics exercise on the cardiac autonomic system. The aim of this study was the nonlinear analysis of the effect of aerobic exercise in the water on the cardiac autonomic system in academic young's males. Materials and Methods: A total of 28 young men were randomly assigned to two groups of control and aerobic exercise in water. In the pre-test period and after the training intervention, all parameters of heart rate variability were measured by examining heart rate sequences, In the pre-test period and after the training intervention, all parameters of heart rate variability were measured by examining heart rate sequences, and then the standard deviation of the recorded sequences was interpreted by using the Poincare plot method. Independent t-test and paired t-test were used to compare the differences in the research stages. Results: Regular participation in aerobic exercise in water caused a significant (45.1±9.2 vs. 34.1±12.3) and standard deviation of time intervals of heart rate sequences compared to their adjacent sequence compared to the control group (P=0.03). The longitudinal standard deviation of time intervals of heart rate sequences compared to the pre-test (P=0.04) had a significant increase (79.5±12.5 vs. 56.9±15.8 After transferring the absolute results to normal, the normal state of the standard deviation of time intervals of heart rate sequences compared to its adjacent sequence compared to the control group (P=0.03) had a significant increase (44.7±12.05 vs. 36.5±13.52). Also, the normal state of the longitudinal standard deviation of time intervals of heart rate sequences compared to the pre-test (P=0.02) increased significantly (76.4±15.29 vs. 61.3±9.32). Conclusion: Performing aerobic exercise in an aqueous environment can be used as a useful training method to improve the responsiveness of the cardiac autonomic system.

Layer-specific dyssynchrony and its relationship to the change of left ventricular function in hypertensive patients.

Left ventricular (LV) remodeling in systemic arterial hypertension causes electrical conduction delay and impairs synchronous contraction, which may contribute to the development of heart failure. This study aimed to assess the change of LV mechanics in hypertension by layer-specific dyssynchrony. One hundred and twenty-one patients with primary hypertension and LV ejection fraction >50 % (mean age, 62 ± 10 years) and 31 normotensive controls (mean age, 63 ± 9 years) were prospectively included. Layer-specific dyssynchrony index (DI) was defined as standard deviation of time interval (TI) from the onset of Q wave to peak longitudinal strain obtained from 18 segments in each endocardial, myocardial, and epicardial layer. The global TI between the onset of Q wave to peak global longitudinal strain in each layer was obtained and the time difference (TD) of global TI between layers was calculated. DIs were significantly different in three layers (P < 0.001 in both groups), and were significantly greater in hypertensive patients than in controls except epicardial DI. End diastolic filling pressure and LV global longitudinal strain were related with endocardial DI. TD between endocardium and myocardium was greater in hypertensive patients than in controls (P = 0.001). Layer-specific DI revealed delayed contraction in each layer and between layers in hypertensive patients, which were apparent in endocardium and between endocardium and myocardium. Increased layer-specific DIs were associated with subclinical LV dysfunction, although LV ejection fraction was preserved. These may be helpful to understand layer-specific mechanical property of LV myocardium and for early detection of subclinical impairment of myocardial function.

Cardiac Sympathetic Dominance and Systemic Inflammation in COPD

Cardiac autonomic dysfunction is an independent determinant of adverse outcomes in many diseases. The available literature on the relative changes in sympathetic and parasympathetic components in chronic obstructive pulmonary disease (COPD) is equivocal, the clinical and physiological correlates are poorly defined and association with markers of systemic inflammation has not been explored. As both autonomic dysfunction and systemic inflammation may contribute to cardiovascular morbidity in COPD, we hypothesized that these may be associated. Sixty three stable patients of COPD and 36 controls underwent spirometry, estimation of diffusion capacity, six-minute walk test and measurements of serum interleukin-6 (IL-6) and high-sensitivity C-Reactive protein. Cardiac autonomic activity was evaluated by standard five-minute heart rate variability (HRV) recordings to obtain time- and frequency-domain indices and the averaged heart rate. We observed that HRV indices of overall autonomic modulation, the standard deviation of time intervals between consecutive normal beats (SDNN) and total power, were greater in patients with higher levels of indices of both parasympathetic and sympathetic activity. The heart rate was significantly higher in patients indicating an overall sympathetic dominance and was inversely correlated with diffusion capacity. Serum IL-6 was inversely correlated with pNN50, an index of parasympathetic activity, and positively with LF/HF ratio, a measure of sympathetic: parasympathetic balance. None of the HRV indices was significantly correlated with physiological measures of severity. It was concluded that patients with COPD have increased cardiac autonomic modulation with sympathetic dominance. This is associated with decreased lung diffusion capacity and systemic inflammation.

A Fast Blind Rendezvous Method by Alternate Hop-and-Wait Channel Hopping in Cognitive Radio Networks

Rendezvous is an essential operation for secondary users communicating in a cognitive radio network (CRN). Because it is infeasible to employ a common control channel in a licensed spectrum, blind rendezvous is an expected solution and generally estimated by the criteria of asynchronous rendezvous support, guaranteed rendezvous, asymmetric model support, heterogeneity of roles, and short time-to-rendezvous (TTR). Most existing blind rendezvous methods fail to fully satisfy these criteria or have considerable TTR significantly increased with the number of channels. This paper presents a new alternate hop-and-wait channel hopping method, called E-AHW, which can support fast blind rendezvous. By assigning each secondary user a unique alternate channel hopping sequence composed of HOP/WAIT-mode subsequences, all blind rendezvous criteria can be satisfied with shorter TTR. According to simulation results, the performance of E-AHW is better than existing methods. Moreover, using E-AHW, the average value and standard deviation of time intervals between two rendezvous are also less than other methods. Thus, E-AHW can provide an efficient and stable communication environment.

Left Ventricular Mechanical Dyssynchrony Impairs Exercise Capacity in Patients With Coronary Artery Disease With Preserved Left Ventricular Systolic Function and a QRS Duration ≤120ms

Left ventricular (LV) mechanical dyssynchrony can lead to impairment of LV function and is associated with adverse clinical outcomes in coronary artery disease (CAD) patients. The impact of LV dyssynchrony on exercise capacity (EC) in patients with CAD was investigated. An echocardiographic examination with tissue Doppler imaging and exercise treadmill testing in 151 CAD patients with normal LV ejection fraction was performed. LV intra- and inter-ventricular dyssynchrony were defined by the standard deviation of time interval between LV 6 basal segments (Ts-SD), and the time interval from the right ventricular (RV) free wall to LV lateral wall (Ts-RV) respectively, and EC was measured as metabolic equivalents (METs) on the treadmill. Patients with impaired EC (defined by a METs ≤ 8, which is the mean MET of the study population) were older (71 ± 7 vs. 62 ± 2 years, P<0.01), however, there were no differences in gender and clinical status such as prevalence of prior myocardial infarction (MI), regional wall motion abnormality (RWMA), and coronary revascularization between patients with (n=90) or without (n=61) impaired EC. Univariate analysis showed that age, body mass index, LV systolic and diastolic volume, mitral inflow A velocity, and Ts-SD were all significantly associated with METs (all P<0.05). However, multivariate regression analysis revealed that old age (odd ratio [OR]: 1.136, 95% confidence interval [CI]: 1.080-1.196, P<0.001), and Ts-SD (OR: 1.026, 95%CI: 1.003-1.049, P=0.027) only were independent predictors for impaired EC. In patients with CAD, LV systolic dyssynchrony predicts impaired EC independently of history of previous MI or RWMA.

Effects of right low atrial septal vs. right atrial appendage pacing on atrial mechanical function and dyssynchrony in patients with sinus node dysfunction and paroxysmal atrial fibrillation

To study the effects of right low atrial septum (AS) and right atrial appendage (RAA) pacing on atrial mechanical function and dyssynchrony in patients with sinus node disease (SND) and paroxysmal atrial fibrillation (AF). Detailed echocardiographic examination was performed on 30 patients with SND and paroxysmal AF and a dual-chamber, dual sensing, dual response pacemaker with atrial lead implantation at AS(n= 15) or RAA(n= 15). Peak atrial velocities were recorded by pulsed tissue Doppler spectrum. The timing of atrial contractions (Ta) was measured at the middle of the left atrial (LA) and right atrial (RA) free wall. Intra-[standard deviation (SD) of time of Ta (Ta-SD)] and inter-atrial delay(Ta-RL) was measured as the SD of time interval among LA six segments and time difference between the LA and RA wall, respectively. The baseline clinical statuses were similar between groups. Indexes of LA function, and intra- or inter-atrial dyssynchrony were also similar during intrinsic sinus rhythm in both groups (all P> 0.05). During atrial pacing, LA ejection fraction (52 ± 16 vs. 39 ± 14%, P= 0.029) and LA active emptying fraction (34 ± 7 vs. 23 ± 15%, P= 0.012) were higher in patients with AS than RAA pacing. Atrial velocity was also higher at the RA free wall (14.3 ± 3.1 vs. 10.3 ± 4.4 cm/s, P= 0.009), LA septal (7.5 ± 2.1 vs. 5.2 ± 1.7 cm/s, P= 0.004) and lateral wall (8.6 ± 2.4 vs. 6.3 ± 3.0 cm/s, P= 0.024) during AS compared with RAA pacing. There was no difference in Ts-SD during atrial pacing, nevertheless Ta-RL was significantly prolonged in patients with RAA compared with those with AS pacing (42 ± 36 vs. 27 ± 25 ms, P= 0.011). In patients with SND and paroxysmal AF, right low AS pacing significantly improved global and regional atrial mechanical function and synchronized inter-atrial electromechanical contraction compared with RAA pacing.

The effect of grain type and processing on equine chewing time

An experiment was conducted to study the hypothesis that increased grain NDF and feed particle size result in increased chewing time in horse. Three adult Standardbred horses (Group I) and 3 adult Icelandic horses (Group II) were fed 3 daily meals during 3 consecutive days in two 3 x 3 completely randomized block design experiments. Meals of (Group I: 1.0 kg and Group II: 0.5 kg) oats, barley and wheat were fed whole, rolled and ground at 10 am, 12 pm, 2 pm. Chewing activity was measured using a special chewing halter. The basic chewing rate is estimated as jaw movements (JM) per min. Efficient chewing time (EPTIME) in min per kg DM is chewing time corrected for pauses. Regularity of JM is standard deviation of time intervals between individual JM. Faecal particle size was analysed using sieving technique and image analysis. The mean EPTIME was 22 and 15 min/kg DM grain (P<0.01) for Icelandic and Standardbred horses, respectively. The basic chewing rate, chewing regularity and faecal particle size did not differ between horses. The EPTIME for whole grain was 18 min/kg DM but not systematically shorter than for ground grain (20 min/kg DM). EPTIME for oats was 21 min/kg DM but not significantly longer than wheat (18 min/kg DM). Jaw movements were systematically more regular during intake of whole grain as compared to ground grain (P<0.01). In conclusion, the presumed hypothesis could not be accepted. The achieved results indicate that regularity of jaw movements during eating provide a new method for quantifying cereal grain characteristics. The achieved results indicate that regularity of jaw movements during eating provide a new biological method for quantifying cereal grain characteristics.

Experimental observation of coherence resonance in an excitable chemical reaction system.

Dynamics of an excitable Belousov-Zabotinsky reaction system under an external noise are investigated using cation exchange beads loaded with the cationic catalyst. When a noise amplitude is increased above a certain value, an oscillatory state appears. It is shown that the coherence of these noise-excited oscillations is maximal for a suitable value of the noise amplitude. This phenomenon is characterized by using various statistical measures, such as the signal-to-noise ratio in the power spectrum, the correlation time of the noise-excited oscillation, and the standard deviation of time intervals between successive firing events. We find the experimental evidence that the period of coherent oscillation is determined by a characteristic time scale of the system.

Discriminant Analysis of Patterns of Jaw Movement During Rumination and Eating in a Cow

Discriminant analysis was used to identify combinations of variables, characterizing patterns of jaw movement (JM) during eating and rumination, that minimize errors when classifying series of successive JM of known behaviour into rumination and eating. JM data from a non-lactating jersey cow were recorded continuously for 72 h. The cow was fed 1800 g of barley straw and 1375 g of dried sugarbeet pulp pellets twice daily. Average times spent eating and ruminating daily were 294 and 462 min. Successive rumination and eating JM were grouped into series when pauses between JM were equal to or longer than a fixed time interval corresponding to the minimum time interval between successive rumination cycles. Time intervals between successive JM, amplitude (the magnitude of the jaw's movement) and number of chews per series of successive JM were calculated for all rumination and eating series and included in the discriminant analyses. The combination of the four variables, basic chewing rate (BCR), mean of amplitude/standard deviation of amplitude, ln(number of chews) and standard deviation of time intervals between successive jaw movements, gave the least minutes of misclassified chewing behaviour per day (3% of total daily chewing time) and yielded a quadratic discriminant function. The order of the variables mentioned rank the variables according to their ability to classify the series. Combinations of the variables BCR and ln(number of chews), and other variables based on mean and standard deviation of time intervals between successive JM and amplitude of JM, can be used with advantage for classifying series of successive JM into rumination and eating behaviour.

"Probabilities of occurrence of large plate rupturing earthquakes for the San Andreas, San Jacinto, and Imperial faults, California,1983–2003""

The San Andreas, San Jacinto, and Imperial faults in California are divided into 19 segments; conditional probabilities are calculated that a particular segment will be the site of a large plate rupturing earthquake, i.e., an event that breaks the entire down‐dip extent of the seismogenic zone, during the next 20 years. The sizes of such events, which account for most of the slip that occurs seismically, appear to vary greatly for different segments of these faults. Repeat time of large shocks, coseismic displacement, moment release, rupture length, and seismic magnitude appear to correlate with one another and to be a function of the tectonic style of different parts of those fault zones. Tectonic inhomogeneities on a scale of about 1 to 100 km are much larger than displacement in any single seismic event and may be regarded as being invariant in their effects upon earthquake generation over many cycles of large shocks. It is this invariance that appears to lead to a given segment of a fault rupturing repeatedly in events of nearly the same size. Since repeat time varies, however, for a given segment of a fault, a simple probabilistic approach is used to forecast the likelihood of large future earthquakes for each segment, using as input the time of the last large shock, the average recurrence time, and the standard deviation of time intervals between events. Dates of the last large shocks are available for most of the segments investigated. Repeat times are estimated from times of historic and prehistoric events, tectonic similarity, and times calculated from coseismic displacement in the last large shock divided by a rate of fault motion or strain buildup. The standard deviation of time intervals divided by the average repeat time is close to 1/3 for three fault segments in California for which data are available on historic and prehistoric earthquakes; that normalized value is adopted for all calculations of conditional probability. Magnitudes and seismic moments of future plate rupturing events are estimated for each fault segment. Several of the segments have well‐constrained probabilities for rupture during the next 20 years, whereas others have large uncertainties. Eight of the segments, constituting about 40% of the total lengths of the three faults, have moderate to high probability and thus should be instrumented and studied extensively so as to provide shorter time warnings. In some cases two adjacent segments may be nearly in phase in their loading history and may break in a single event. The segment of the San Andreas fault from opposite San Jose to San Juan Bautista, which ruptured less than 1.5 m in 1906 and which probably also broke in 1838, is calculated to have a moderate to high probability of an earthquake of magnitude 6¾ to ¼ during the next 20 years. A 325 km section of the southern San Andreas between Tejon Pass and the Salton Sea has about a 25% chance of rupturing in a shock of magnitude near 8 during the next 20 years. All the other segments have only a small chance (i.e., less than 5 to 10%) of rupturing in an event of magnitude near 8 during that interval.