So just what is a Linear Time-Invariant (LTI) system, and why should you care? Systems are used to perform signal processing. The effect of a system on the spectrum of a signal can be analyzed easily if and only if the system is LTI, as we will see in these notes. The ability to design a filter to perform a specific signal processing task (e.g., filter out noise, differentiate, equalize frequen...

We consider uncertain fractional-order linear time invariant (FO-LTI) systems with interval coefficients. Our focus is on the robust controllability issue for interval FO-LTI systems in statespace form. We re-visited the controllability problem for the case when there is no interval uncertainty. It turns out that the stability check for FO-LTI systems amounts to checking the conventional intege...

This paper revisits the definition of linear time-invariant (LTI) stochastic process within a behavioral systems framework. Building on Willems (2013), we derive a canonical representation of an LTI stochastic process and a physically grounded notion of interconnection between independent stochastic processes. We use this framework to analyze the invariance properties enjoyed by distances betwe...

Hematopoietic lymphoid tissue inducer (LTi) cells are essential for the development of secondary lymphoid tissues including lymph nodes and Peyer's patches. Two transcription factors, the helix-loop-helix inhibitor Id2 and the retinoic acid-related orphan receptor γt (Rorγt), have been shown to be crucial for LTi cell development. However, it remains unclear how the specification of multipotent...

The leader-following consensus of multiple linear time invariant (LTI) systems under switching topology is considered. The leader-following consensus problem consists of designing for each agent a distributed protocol to make all agents track a leader vehicle, which has the same LTI dynamics as the agents. The interaction topology describing the information exchange of these agents is time-vary...

BACKGROUND The prevalence of cardiovascular disease (CVD) has increased steadily in recent years. Literature data show that about 35% of atherosclerotic events occur in the absence of classic risk factors, requiring a broader assessment of the individual to better characterize the risk. Lipid Tetrad Index (LTI) and Lipid Pentad Index (LPI) constitute a new and efficient evaluation of the lipid ...

Lymphoid tissue inducer (LTi) cells are required for lymph node formation during fetal development, and recent evidence implies a role in mucosal immunity in the adult. LTi cells share some phenotypic features of conventional natural killer (NK; cNK) cells; however, little is known to date about the relationship between these two cell types. We show that lineage(-) (Lin(-)) CD127(+)RORC(+) LTi-...

Characteristics of inhibitors identified by prospective screening may differ from those detected clinically. In a prospective study at 17 hemophilia centers with central inhibitor measurement by Nijmegen-Bethesda assay, 23 (2.8%) of 824 hemophilia A patients had new inhibitors detected: nine high-titer inhibitors (HTI: 7 ≥ 5.0 NBU plus 2 of 2.6 and 3.4 NBU at immune tolerance induction initiati...

Approximations of slightly nonlinear systems with linear time-invariant (LTI) models are often used in applications. Here, LTI models that are optimal approximations in the mean-square error sense are studied. It is shown that these models can be very sensitive to small nonlinearities. Furthermore, the significance of the distribution of the input process is discussed. From the examples studied...