Behavioral-Independent Features of Complex Heartbeat Dynamics

We test whether the complexity of cardiac interbeat interval time series is simply a consequence of the wide range of scales characterizing human behavior, especially physical activity, by analyzing data taken from healthy adult subjects under three conditions with controls: (i) a ``constant routine'' protocol where physical activity and postural changes are kept to a minimum, (ii) sympathetic blockade, and (iii) parasympathetic blockade. We find that when fluctuations in physical activity and other behavioral modifiers are minimized, a remarkable level of complexity of heartbeat dynamics remains, while for neuroautonomic blockade the multifractal complexity decreases.Comment: 4 pages with 6 eps figures. Latex file. For more details or for downloading the PDF file of the published article see http://polymer.bu.edu/~amaral/Heart.html and http://polymer.bu.edu/~amaral/Multifractal.htm

FAKTOR-FAKTOR PEMBENTUK PERILAKU PELANGGAN "PINNOCHIO" DI KUPANG

Understanding why exaggerated negative word of mouth customers complain the way they do is important from theorical, managerial and public policy perspectives. This research try to answer customer negative WOM and desirable organizational outcomes, the possibility that customer might routinely exaggerate their consumption experience stories has been neglected. This research uses non-random sampling method (convenience sampling) in order to collect data. 138 people in Kupang were used as respondents. Data were collected using questionnaire (google form). This study uses SEM analyze to test the data. The result suggested consumer dissatisfaction and consumer vanting had effect toward exaggerated negative word of mouth, interactional justice and perceived tie had no effect toward exaggerated negative word of mouth.   Keywords: word of mouth, exaggeration, negative word of mouth, consumer dissatisfaction, consumer ventingUnderstanding why exaggerated negative word of mouth customers complain the way they do is important from theorical, managerial and public policy perspectives. This research try to answer customer negative WOM and desirable organizational outcomes, the possibility that customer might routinely exaggerate their consumption experience stories has been neglected. This research uses non-random sampling method (convenience sampling) in order to collect data. 138 people in Kupang were used as respondents. Data were collected using questionnaire (google form). This study uses SEM analyze to test the data. The result suggested consumer dissatisfaction and consumer vanting had effect toward exaggerated negative word of mouth, interactional justice and perceived tie had no effect toward exaggerated negative word of mouth.   Keywords: word of mouth, exaggeration, negative word of mouth, consumer dissatisfaction, consumer ventin

Stochastic Feedback and the Regulation of Biological Rhythms

We propose a general approach to the question of how biological rhythms spontaneously self-regulate, based on the concept of ``stochastic feedback''. We illustrate this approach by considering the neuroautonomic regulation of the heart rate. The model generates complex dynamics and successfully accounts for key characteristics of cardiac variability, including the $1/f$ power spectrum, the functional form and scaling of the distribution of variations, and correlations in the Fourier phases. Our results suggest that in healthy systems the control mechanisms operate to drive the system away from extreme values while not allowing it to settle down to a constant output.Comment: 15 pages, latex2e using rotate and epsf, with 4 ps figures. Submitted to PR

DETERMINANT FACTORS OF MOBILE BANKING USAGE: CASE STUDY IN KUPANG, EAST NUSA TENGGARA

A review of previous research on m-banking in developing countries reveals that research on the drivers of trust in mobile banking is somewhat limited. Therefore, this study attempts to investigate the factors that influence the user's perception of confidence in mobile banking services. This model was tested empirically using an online survey from a convenience sampling of 95 respondents and analyzed using SEM PLS. This study estimates that six variables (perceived credibility, perceived benefits, security risks, privacy risks, social influence, and perceived behavioral control) directly impact perceived trust in mobile banking. The results, in particular, perceived benefits positively affect perceived trust in mobile banking, followed by social influence, security risk, and privacy risk has power on perceived trust in mobile banking. On the other hand, perceived credibility and PBC show no significant effect on the belief of mobile banking users

Scale Invariance in the Nonstationarity of Physiological Signals

We introduce a segmentation algorithm to probe temporal organization of heterogeneities in human heartbeat interval time series. We find that the lengths of segments with different local values of heart rates follow a power-law distribution. This scale-invariant structure is not a simple consequence of the long-range correlations present in the data. We also find that the differences in mean heart rates between consecutive segments display a common functional form, but with different parameters for healthy individuals and for patients with heart failure. This finding may provide information into the way heart rate variability is reduced in cardiac disease.Comment: 13 pages, 5 figures, corrected typo

Dynamics of Sleep-Wake Transitions During Sleep

We study the dynamics of the awakening during the night for healthy subjects and find that the wake and the sleep periods exhibit completely different behavior: the durations of wake periods are characterized by a scale-free power-law distribution, while the durations of sleep periods have an exponential distribution with a characteristic time scale. We find that the characteristic time scale of sleep periods changes throughout the night. In contrast, there is no measurable variation in the power-law behavior for the durations of wake periods. We develop a stochastic model which agrees with the data and suggests that the difference in the dynamics of sleep and wake states arises from the constraints on the number of microstates in the sleep-wake system.Comment: Final form with some small corrections. To be published in Europhysics Letters, vol. 57, issue no. 5, 1 March 2002, pp. 625-63

Tissue multifractality and Born approximation in analysis of light scattering: a novel approach for precancers detection

Multifractal, a special class of complex self-affine processes, are under recent intensive investigations because of their fundamental nature and potential applications in diverse physical systems. Here, we report on a novel light scattering-based inverse method for extraction/quantification of multifractality in the spatial distribution of refractive index of biological tissues. The method is based on Fourier domain pre-processing via the Born approximation, followed by the Multifractal Detrended Fluctuation Analysis. The approach is experimentally validated in synthetic multifractal scattering phantoms, and tested on biopsy tissue slices. The derived multifractal properties appear sensitive in detecting cervical precancerous alterations through an increase of multifractality with pathology progression, demonstrating the potential of the developed methodology for novel precancer biomarker identification and tissue diagnostic tool. The novel ability to delineate the multifractal optical properties from light scattering signals may also prove useful for characterizing a wide variety of complex scattering media of non-biological origin

Multifractal properties of resistor diode percolation

Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the non-percolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents $\{\psi_l \}$. We calculate the family $\{\psi_l \}$ to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods.Comment: 21 pages, 5 figures, to appear in Phys. Rev.