10 research outputs found
On the preservation of co-positive Lyapunov functions under Padé discretization for positive systems
In this paper the discretization of switched and
non-switched linear positive systems using Padé approximations
is considered. We show:
1) first order diagonal Padé approximation preserves both
linear and quadratic co-positive Lyapunov functions,
higher order transformations need an additional condition
on the sampling time1;
2) positivity need not be preserved even for arbitrarily small
sampling time for certain Padé approximations.
Sufficient conditions on the Padé approximations are given to
preserve positivity of the discrete-time system. Finally, some
examples are given to illustrate the efficacy of our results
Molecular Characterization of Cancer Associated Fibroblasts in Prostate Cancer
Background: Stromal components surrounding epithelial cancer cells seem to play a pivotal
role during epithelial-to-mesenchymal transition (EMT), tumor invasion, and metastases. To identify
the molecular mechanisms underlying tumor–stroma interactions may yield novel therapeutic targets
for prostate cancer. Methods: Gene expression profile of prostate-cancer associated fibroblast (PCAF)
and prostate non-cancer associated fibroblast (PNAF) cells isolated from radical prostatectomy was
performed by Illumina, analyzed, and further processed by Ingenuity®: IPA® software. qRT-PCR
was performed on an independent set of 17 PCAF, 12 PNAF, and 12 fibroblast cell lines derived from
patients with benign prostatic hyperplasia (BPHF). Results: Using microarray analysis, we found
six upregulated genes and two downregulated genes in PCAFs compared to PNAFs. To validate microarray results, we performed qRT-PCR for the most significantly regulated genes involved in
the modulation of proliferation and androgen resistance on an independent set of PNAF, PCAF, and
BHPF samples. We confirmed the increased expression of SCARB1, MAPK3K1, and TGF-β as well as
the decreased expression of S100A10 in PCAFs compared to PNAFs and BPHFs. Conclusions: These
results provide strong evidence that the observed changes in the gene expression profile of PCAFs
can contribute to functional alteration of adjacent prostate cancer cells
Molecular Characterization of Cancer Associated Fibroblasts in Prostate Cancer
Background: Stromal components surrounding epithelial cancer cells seem to play a pivotal role during epithelial-to-mesenchymal transition (EMT), tumor invasion, and metastases. To identify the molecular mechanisms underlying tumor-stroma interactions may yield novel therapeutic targets for prostate cancer. Methods: Gene expression profile of prostate-cancer associated fibroblast (PCAF) and prostate non-cancer associated fibroblast (PNAF) cells isolated from radical prostatectomy was performed by Illumina, analyzed, and further processed by Ingenuity (R) : IPA (R) software. qRT-PCR was performed on an independent set of 17 PCAF, 12 PNAF, and 12 fibroblast cell lines derived from patients with benign prostatic hyperplasia (BPHF). Results: Using microarray analysis, we found six upregulated genes and two downregulated genes in PCAFs compared to PNAFs. To validate microarray results, we performed qRT-PCR for the most significantly regulated genes involved in the modulation of proliferation and androgen resistance on an independent set of PNAF, PCAF, and BHPF samples. We confirmed the increased expression of SCARB1, MAPK3K1, and TGF-beta as well as the decreased expression of S100A10 in PCAFs compared to PNAFs and BPHFs. Conclusions: These results provide strong evidence that the observed changes in the gene expression profile of PCAFs can contribute to functional alteration of adjacent prostate cancer cells
On the preservation of co-positive Lyapunov functions under Padédiscretization for positive systems
On the preservation of co-positive Lyapunov functions under Padé discretization for positive systems
In this paper the discretization of switched and
non-switched linear positive systems using Padé approximations
is considered. We show:
1) first order diagonal Padé approximation preserves both
linear and quadratic co-positive Lyapunov functions,
higher order transformations need an additional condition
on the sampling time1;
2) positivity need not be preserved even for arbitrarily small
sampling time for certain Padé approximations.
Sufficient conditions on the Padé approximations are given to
preserve positivity of the discrete-time system. Finally, some
examples are given to illustrate the efficacy of our results
On the preservation of co-positive Lyapunov functions under Padé discretization for positive systems
In this paper the discretization of switched and
non-switched linear positive systems using Padé approximations
is considered. We show:
1) first order diagonal Padé approximation preserves both
linear and quadratic co-positive Lyapunov functions,
higher order transformations need an additional condition
on the sampling time1;
2) positivity need not be preserved even for arbitrarily small
sampling time for certain Padé approximations.
Sufficient conditions on the Padé approximations are given to
preserve positivity of the discrete-time system. Finally, some
examples are given to illustrate the efficacy of our results
On the preservation of co-positive Lyapunov functions under Padé discretization for positive systems
In this paper the discretization of switched and
non-switched linear positive systems using Padé approximations
is considered. We show:
1) first order diagonal Padé approximation preserves both
linear and quadratic co-positive Lyapunov functions,
higher order transformations need an additional condition
on the sampling time1;
2) positivity need not be preserved even for arbitrarily small
sampling time for certain Padé approximations.
Sufficient conditions on the Padé approximations are given to
preserve positivity of the discrete-time system. Finally, some
examples are given to illustrate the efficacy of our results
Designing On-Demand Four-Wheel-Drive Vehicles via Active Control of the Central Transfer Case
New driveline architectures equipped with torquebiasing
devices such as active differentials and active transfer
cases have yielded a new generation of on-demand four-wheel-drive vehicles, where the torque distribution between left and right and between front and rear axles can actively be modulated online. This allows one to design active vehicle-control systems that are capable of altering, via electronic control, the behavior of a car dictated from its mechanical layout, e.g., understeering and oversteering characteristics. This paper proposes a control strategy that optimizes vehicle performance while guaranteeing vehicle stability and drivability by actively controlling the transfer case. The performance of the overall control strategy is assessed on both a multibody simulator and an instrumented test vehicle
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)
In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field