Narrow Results

The directional effects of near-fault ground motions significantly influence the severity and damage patterns of transportation infrastructure. However, the directional characteristics of ground motion duration, particularly for long-period motions, remain unclear. This study investigates the response spectra and duration spectra of near-fault long-period ground motions recorded during the Noto Peninsula earthquake on January 1, 2014. A novel method, called the omnidirectional duration spectrum, is proposed to investigate the characteristics of long-period ground motion duration. This approach provides an intuitive visualization of the relationships among duration, period, and direction. When combined with omnidirectional response spectra, this method is applied to analyze ground motion records from five stations near the fault during the earthquake, examining the relationship between ground motion directionality and fault strike. The study further details the damage characteristics observed in railway and highway systems during the earthquake. A statistical analysis is conducted to evaluate the damage across different intensity zones, highlighting the correlation between damage patterns and the directionality of strong ground motion records near fault. Finally, the seismic design of transportation structures in the hanging wall region of reverse faults is discussed. The results reveal that uniform duration spectra effectively capture the dominant directional characteristics of ground motion duration, whereas significant duration spectra lack clear directionality for longer periods. The Noto Peninsula earthquake exhibited prominent directional characteristics in near-fault long-period ground motions, with maximum directionality aligned with the reverse fault rupture direction on the fault slip plane. The dominant period range for these motions was 1.6–8s, closely matching the damage patterns of long-period structures such as railways and highways in the strong motion region. The settlement of bridge abutments and the design of landslide protections along highways should comprehensively account for the characteristics of potential seismogenic faults, and corresponding seismic measures should be implemented.

Changes in heart rate, most often increases, are associated with the onset of epileptic seizures and may be used in lieu of cortical activity for automated seizure detection. The feasibility of this aim was tested on 241 clinical seizures from 81 subjects admitted to several Epilepsy Centers for invasive monitoring for evaluation for epilepsy surgery. The performance of the EKG-based seizure detection algorithm was compared to that of a validated algorithm applied to electrocorticogram (ECoG). With the most sensitive detection settings [threshold T: 1.15; duration D: 0 s], 5/241 seizures (2%) were undetected (false negatives) and with the highest [T: 1.3; D: 5 s] settings, the number of false negative detections rose to 34 (14%). The rate of potential false positive (PFP) detections was 9.5/h with the lowest and 1.1/h with the highest T, D settings. Visual review of 336 ECoG segments associated with PFPs revealed that 120 (36%) were associated with seizures, 127 (38%) with bursts of epileptiform discharges and only 87 (26%) were true false positives. Electrocardiographic (EKG)-based seizure onset detection preceded clinical onset by 0.8 s with the lowest and followed it by 13.8 s with the highest T, D settings. Automated EKG-based seizure detection is feasible and has potential clinical utility given its ease of acquisition, processing, high signal/noise and ergonomic advantages viz-a-viz EEG (electroencephalogram) or ECoG. Its use as an "electronic" seizure diary will remedy in part, the inaccuracies of those generated by patients/care-givers in a cost-effective manner.

This paper examines how socio-demographic and health-lifestyle factors determine participation and duration of leisure-time physical activity in Malaysia. Based on the Malaysia Non-Communicable Disease Surveillance-1 data, Heckman's sample selection model is employed to estimate the probability to participate and duration on physical activity. Results indicate that gender, age, years of education and family illness history are significant in explaining participation probability in leisure-time physical activity. Gender, income level, smoking-status and years of education are significant in explaining the weekly duration conditional on participation, whereas smoking-status and years of education are significant in determining the unconditional level of leisure-time physical activity.

Credit risk is an important issue of current research in finance. While there is a lot of work on modeling credit risk, there is only a few works on continuous-time portfolio optimization with defaultable securities. In this paper we solve investment problems with defaultable bonds and stocks. We assume that credit risk is modeled by a firm value model.

Duration and convexity are important measures in fixed-income portfolio management. In this paper, we analyze this measure of the bonds by applying the beta model. The general usefulness of the beta probability distribution enhances its applicability in a wide range of reliability analyses, especially in the theory and practice of reliability management. We estimate the beta density function of the duration/convexity. This estimate is based on two important and simple models of short rates, namely, Vasicek and CIR (Cox, Ingersoll, and Ross CIR). The models are described and then their sensitivity of the models with respect to changes in the parameters is studied. We generate the stochastic interest rate on the duration and convexity model. The main results show that the beta probability distribution can be applied to model each phase of the risk function. This distribution approved its effectiveness, simplicity and flexibility. In this paper, we are interested in providing a decision-making tool for the manager in order to minimize the portfolio risk. It is helpful to have a model that is reasonably simple and suitable to different maturity of bonds. Also, it is widely used by investors for choosing bond portfolio immunization through the investment strategy. The finding also shows that the probability of risk measured by the reliability function is to highlight the relationship between duration/convexity and different risk levels. With these new results, this paper offers several implications for investors and risk management purposes.

It is generally perceived that ground motion duration has an effect on structural seismic response and damage, despite the neglect of current seismic codes. Based on friction SDOF systems, this paper investigates the duration effect of ground motions on seismic responses and damage of sliding bearings. Ground motions are divided into long-duration (LD) and short-duration (SD) cases, taking the significant duration of 25s as the boundary. Each case consists of natural records and spectrally equivalent artificial ground motions to decouple duration from other earthquake characteristics. Results from response history analyses implicate that duration has hardly any effect on seismic responses of the system exhibiting an approximate linear elasticity. Nevertheless, for systems with distinct frictional nonlinearity, selecting LD ground motions as seismic inputs usually leads to a conservative result. By performing incremental dynamic analysis (IDA), nonlinear systems in SD cases bear 10% higher damage risk than those in LD cases without considering the influence of temperature rise. The same is true for systems with a small friction coefficient of 0.005 when earthquakes are in the low intensity range. It was also found that damage exceedance probabilities of these small friction coefficient systems are almost unaffected by the duration as the peak ground acceleration increases to more than 0.6$g$. When the effect of temperature rise caused by friction is considered, the damage exceedance probability in LD cases is higher than SD cases. The damage probability of friction SDOF system under LD earthquake will be underestimated without considering the influence of temperature rise.

A dataset of 690 strong motion component records of horizontal accelerations are analysed to derive predictive relationships for Arias Intensity, duration and number of pulses as functions of acceleration level as well as their dependence on the magnitude and distance of the source. The relationships show that the records should follow the patterns set by such relationships and cannot entirely be random. The use of some of the parameters to generate artificial time histories of acceleration is shown merely as an example.

Chile presents a high seismicity and very particular characteristics due to its subductive environment and high convergence rate of the interacting plates. In this paper, ground motion models (GMM) for Arias Intensity and strong ground motion duration are developed based on recently compiled Chilean earthquakes records. The Chilean derived GMM are later compared with global and subduction models. For the duration case, two definitions are considered: significant duration and bracketed duration. Care is taken to consider newly define rupture areas for the major earthquake in the catalog, which allows to redefine the distances to be used in the analysis. The strong motion records are processed using robust techniques and standardized procedures. The model parameters are selected using a Bayesian updating method. This allows to estimate the parameters as well as their corresponding uncertainties recognizing the variability of the coefficients and of the selected model. The derived ground motion predictive model associated is validated through a residual analysis and probability distributions, obtained from the adjustment method. Additionally, for the bracketed duration analysis, a classification method based on Support Vector Machine (SVM) is used, with the aim to incorporate the records with duration of zero seconds. The comparison of the resultant model with the existing ones allows to confirm the differences that the tectonic Chilean environment produces, characterized mainly by a high relative convergence rate between plates and interplate thrust earthquakes with high magnitudes.

This paper identifies a fundamental relationship between the present value of a given cash flow and the present value of the period by period change in that cash flow. The new relationship is shown to be highly useful for the identification of analytic expressions for present value and related measures such as duration and convexity; expressions that continue to play an instructive role by helping to relate the quantitative outcomes of numerical calculations to the driving forces behind those calculations. This new method applies only simple arithmetic operations and avoids the use of differential calculus and advanced series summation in order to derive these analytic results.

We apply the method to a variety of nontraditional cash flows, including cash flows with linear growth or decay, cash flows that are subject to different tax effects for dividends and capital gain, and cash flows that are projected to exhibit cyclical variation over time.

A variety of approaches have been proposed to extend classical fixed income portfolio immunization theory to cases where shifts in the term structure are not parallel. Following Reitano (1991a, 1991b, 1992, 1996) and Poitras (2007), this paper uses partial durations and convexities to specify benchmark partial immunization bounds for non-parallel term structure shifts. Theoretical results are obtained by exploiting properties of the multivariate Taylor series expansion of the spot interest rate pricing function. It is demonstrated that the partial immunization bounds can be effectively manipulated by adequate selection of the securities being used to immunize the portfolio. The inclusion of time values permits the results obtained to be related to previous studies by Christensen and Sorensen (1994), Chance and Jordan (1996), Barber and Copper (1997) and Poitras (2005, Ch. 5) on the time value-convexity tradeoff.

This chapter first focuses on the bond strategies of riding the yield curve and structuring the maturity of the bond portfolio in order to generate additional return. This is followed by a discussion of swapping, which are essentially interest-rate swaps. Next is an analysis of duration or the measure of the portfolio sensitivity to changes in interest rates with and without convexity, after which immunization is the focus. The convexity is essentially discussed in nonlinear relationship between bond price and duration. Finally, a case study is presented of bond-portfolio management in the context of portfolio theory. Overall, this chapter presents how interest rate changes affect bond price and how maturity and duration can be used to manage portfolios.

This chapter first focuses on the bond strategies of riding the yield curve and structuring the maturity of the bond portfolio in order to generate additional return. This is followed by a discussion on swapping, which is essentially interest-rate swapping. Next is an analysis of duration or the measure of the portfolio sensitivity to changes in interest rates with and without convexity, after which immunization is the focus. The convexity is essentially discussed as a nonlinear relationship between bond price and duration. Finally, a case study of bond-portfolio management is presented in the context of portfolio theory. Overall, this chapter presents how interest rates change affect bond price and how maturity and duration can be used to manage portfolios.

Movie shots of singular scenes have a preferential duration of 2 to 3 s regardless of producers, movie types, and cultural environments. This observation suggests that the temporal structure of movies matches a neural mechanism of information processing in the time domain.

In the contemporary philosophy of mind, the notion of subjective experience plays a central role. One of the most interesting dimensions of the subjective experience is its time dimension. In this paper I will attempt to develop a plausible model of subjective experience of time based on the following conceptual tools: on the metaphor of the ‘Specious Present’ developed by William James and on the concept of the ‘Thick Moment’ of consciousness, introduced by the British psychologist Nicholas Humphrey. Subsequently, I will deal with two basic properties of time experience: change and duration. I will examine their relation to the previously introduced container view of consciousness. In the second part of this paper, I will apply this model of conscious time experience on some ‘extraordinary’ time experiences to see how this model can accommodate this type of experiences.