scholarly journals Cardiovascular control and time domain Granger causality: insights from selective autonomic blockade

2013 ◽  
Vol 371 (1997) ◽  
pp. 20120161 ◽  
Author(s):  
Alberto Porta ◽  
Paolo Castiglioni ◽  
Marco Di Rienzo ◽  
Tito Bassani ◽  
Vlasta Bari ◽  
...  
Keyword(s):  
Granger Causality ◽  
Time Domain ◽  
Closed Loop ◽  
Systolic Arterial Pressure ◽  
Cardiovascular Control ◽  
Causal Direction ◽  
Autonomic Blockade ◽  
Definition Of ◽  
The Time Domain ◽  
Bidirectional Interactions

We studied causal relations among heart period (HP), systolic arterial pressure (SAP) and respiration (R) according to the definition of Granger causality in the time domain. Autonomic pharmacological challenges were used to alter the complexity of cardiovascular control. Atropine (AT), propranolol and clonidine (CL) were administered to block muscarinic receptors, β-adrenergic receptors and centrally sympathetic outflow, respectively. We found that: (i) at baseline, HP and SAP interacted in a closed loop with a dominant causal direction from HP to SAP; (ii) pharmacological blockades did not alter the bidirectional closed-loop interactions between HP and SAP, but AT reduced the dominance of the causal direction from HP to SAP; (iii) at baseline, bidirectional interactions between HP and R were frequently found; (iv) the closed-loop relation between HP and R was unmodified by the administration of drugs; (v) at baseline, unidirectional interactions from R to SAP were often found; and (vi) while AT induced frequently an uncoupling between R and SAP, CL favoured bidirectional interactions. These results prove that time domain measures of Granger causality can contribute to the description of cardiovascular control by suggesting the temporal direction of the interactions and by separating different causality schemes (e.g. closed loop versus unidirectional relations).

Discrete Time, Discrete Frequency

2021 ◽  
pp. 106-155
Author(s):  
Victor Lazzarini
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Discrete Time ◽  
Time Domain ◽  
Continuous Time ◽  
Time Varying ◽  
Discrete Frequency ◽  
The Fourier Transform ◽  
Definition Of ◽  
The Time Domain

This chapter is dedicated to exploring a form of the Fourier transform that can be applied to digital waveforms, the discrete Fourier transform (DFT). The theory is introduced and discussed as a modification to the continuous-time transform, alongside the concept of windowing in the time domain. The fast Fourier transform is explored as an efficient algorithm for the computation of the DFT. The operation of discrete-time convolution is presented as a straight application of the DFT in musical signal processing. The chapter closes with a detailed look at time-varying convolution, which extends the principles developed earlier. The conclusion expands the definition of spectrum once more.

Suspending the “Time Domain” : Technological Tempor(e)alities of Media Infrastructures

2021 ◽  
Author(s):  
Wolfgang Ernst
Keyword(s):  
Time Domain ◽  
Time Function ◽  
Archaeological Investigation ◽  
Temporal Structures ◽  
Definition Of ◽  
The Time Domain ◽  
Effects Of Media ◽  
Media Event

Any media event is a time function of signals. In favor of a diagrammatic definition of technological media, media archaeological investigation is not only concerned with their structural “hardwired” level but with their operative unfolding-in-time as well. Such an understanding of techno-temporalities does not focus on phenomenal effects of media on humans but primarily refers to the microregimes within technological devices. In that sense, “hardwired temporality” refers to the infrastructuring of time by technologies and to temporal structures which are revealed from within techno-logical knowledge itself. From that arises an epistemology of technical processuality beyond the conventional notion of “time.”

scholarly journals Introduction to Communication Systems

2021 ◽  
pp. 1-17
Author(s):  
Stevan Berber
Keyword(s):  
Theoretical Analysis ◽  
Time Domain ◽  
Communication Systems ◽  
Theoretical Concepts ◽  
Analysis And Design ◽  
The Subject ◽  
Definition Of ◽  
The Time Domain ◽  
Analogue To Digital ◽  
Power And Energy

This chapter introduces the subject of the book, defines the main terms in communication systems that will be used in the book, and presents the objectives of the book. It also presents classifications of signals and systems, and theoretical concepts related to the signal conversions in the time domain that will be used in subsequent chapters. The signals are classified using various criteria, including periodicity and symmetry, continuity and discreteness, power and energy properties, randomness, and physical realizability of signals. Analogue-to digital and digital-to-analogue conversions and their places and importance in the processing of signals in relation to their application in communication systems are briefly explained. The final section returns back to the definition of the signals related to the continuity and discreteness in time and their values, due to the importance of distinguishing them in the theoretical analysis and design of digital and discrete communication systems.

Spectral Moments and Pre-Envelope Covariances of Nonseparable Processes

1990 ◽  
Vol 57 (1) ◽  
pp. 218-224 ◽  
Author(s):  
Mario Di Paola ◽  
Giovanni Petrucci
Keyword(s):  
Stochastic Process ◽  
Time Domain ◽  
Critical Review ◽  
Stationary Case ◽  
Spectral Moments ◽  
Definition Of ◽  
The Time Domain ◽  
Made In

A critical review of the definition of the spectral moments of a stochastic process in the nonstationary case is presented. An adequate time-domain representation of the spectral moments in the stationary case is first established, showing that the spectral moments are related to the variances of the stationary analytical pre-envelope processes. The extension to the nonstationary case is made in the time domain evaluating the covariances of the nonstationary pre-envelope showing the differences between the proposed definition and the classical one made introducing the evolutionary power.

Spectral balancing in the time domain

Geophysics ◽  
1981 ◽  
Vol 46 (8) ◽  
pp. 1182-1188 ◽  
Author(s):  
D. Tufekčić ◽  
J. F. Claerbout ◽  
Z. Rašperić
Keyword(s):  
Time Domain ◽  
Seismic Data ◽  
Recent Interest ◽  
Definition Of ◽  
The Time Domain

The recent interest in deconvolution and the variety of new deconvolution methods in use demonstrates the importance and complexity of this problem. Each of the existing methods has some advantages for optimum enhancement of definition of seismic data. We believe that the spectral balancing method considered here is appropriate for data in which the frequencies of the organized noise are rather complex, e.g., land data shot by surface sources.

Sign in / Sign up

Export Citation Format

Share Document