| 1. |
- Delvenne, A., et al.
(författare)
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Cerebrospinal fluid proteomic profiling of individuals with mild cognitive impairment and suspected non-Alzheimer's disease pathophysiology
- 2023
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 19:3, s. 807-820
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Tidskriftsartikel (refereegranskat)abstract
- Background Suspected non-Alzheimer's disease pathophysiology (SNAP) is a biomarker concept that encompasses individuals with neuronal injury but without amyloidosis. We aim to investigate the pathophysiology of SNAP, defined as abnormal tau without amyloidosis, in individuals with mild cognitive impairment (MCI) by cerebrospinal fluid (CSF) proteomics. Methods Individuals were classified based on CSF amyloid beta (A beta)1-42 (A) and phosphorylated tau (T), as cognitively normal A-T- (CN), MCI A-T+ (MCI-SNAP), and MCI A+T+ (MCI-AD). Proteomics analyses, Gene Ontology (GO), brain cell expression, and gene expression analyses in brain regions of interest were performed. Results A total of 96 proteins were decreased in MCI-SNAP compared to CN and MCI-AD. These proteins were enriched for extracellular matrix (ECM), hemostasis, immune system, protein processing/degradation, lipids, and synapse. Fifty-one percent were enriched for expression in the choroid plexus. Conclusion The pathophysiology of MCI-SNAP (A-T+) is distinct from that of MCI-AD. Our findings highlight the need for a different treatment in MCI-SNAP compared to MCI-AD.
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| 2. |
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| 3. |
- Sandberg, Henrik, et al.
(författare)
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The Statistical Mechanics of Fluctuation-Dissipation and Measurement Back Action
- 2007
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Ingår i: 2007 AMERICAN CONTROL CONFERENCE, VOLS 1-13. ; , s. 1033-1038
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Konferensbidrag (refereegranskat)abstract
- In this paper, we take a control-theoretic approach to answering some standard questions in statistical mechanics. A central problem is the relation between systems which appear macroscopically dissipative but are microscopically lossless. We show that a linear macroscopic system is dissipative if and only if it can be approximated by a linear lossless microscopic system, over arbitrarily long time intervals. As a by-product, we obtain mechanisms explaining Johnson-Nyquist noise as initial uncertainty in the lossless state, as well as measurement back action and a trade-off between process and measurement noise.
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| 4. |
- Schofield, PN, et al.
(författare)
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Pathbase: a database of mutant mouse pathology
- 2004
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Ingår i: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962. ; 32:Database issue, s. D512-D515
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Sandberg, Henrik, et al.
(författare)
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Thermodynamic costs in implementing Kalman-Bucy filters
- 2014
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Ingår i: 2014 52nd Annual Allerton Conference on Communication, Control, and Computing. - 9781479980093 ; , s. 550-555
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate fundamental limits for physical implementations of the Kalman-Bucy filter for state estimation of a class of linear port-Hamiltonian systems. In particular, for the studied class of systems we show the Kalman-Bucy filter itself is a port-Hamiltonian systems and by invoking the second law of thermodynamics, we can characterize the external power supply needed to generate an optimal state estimate. We also show how the required external power supply can be decreased by allowing the filter to perturb the measured system to a larger extent. Hence, it is possible to decrease the so-called back action of the filter by spending more energy. We illustrate our results using passive electric circuits.
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| 6. |
- Delvenne, J. -C, et al.
(författare)
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Deriving thermodynamics from linear dissipativity theory
- 2016
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : IEEE conference proceedings. - 9781479978861 ; , s. 537-542
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Konferensbidrag (refereegranskat)abstract
- Complete and rigorous foundations for basic thermodynamic laws from the statistical description of microscopic systems has been a long-standing goal for mathematicians and physicists alike since Boltzmann. In this paper, we show how Willems's dissipativity theory provides a convenient framework to study a physical system at both microscopic and macroscopic level, and suggests a natural storage function different from the usual free energy to derive the theorem of energy equipartition of energy for linear systems. In this setup, we introduce a simple and general definition for temperature defined also out of equilibrium which allows to test the limits of validity of Fourier's law describing the transfer of heat from hot systems to cold systems. In particular under time-scale separation conditions, we derive the Maxwell-Cattaneo law, allowing for instantaneous flow of energy from cold to hot systems, which should be considered instead of Fourier's law for a proper description of energy exchanges between interconnected linear systems.
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| 7. |
- Delvenne, J. -C, et al.
(författare)
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Towards a thermodynamics of control : Entropy, energy and Kalman filtering
- 2013
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Ingår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC). - : IEEE conference proceedings. - 9781467357173 ; , s. 3109-3114
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Konferensbidrag (refereegranskat)abstract
- We propose a method to analyse the flows of information and energy between two systems (plant and controller) connected in feedback. Extending a work by Touchette and Lloyd (2000, 2004), we estimate the advantage, both in terms of entropy reduction and energy extraction, of a feedback controller over an open-loop control in terms of the information on the plant state that is available to the controller. By energy here we mean any objective function that we seek to minimize, for example the square of the state. We apply this methodology on the Kalman filter, and develop a physical interpretation comparable to Mitter and Newton's (2005).
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