Robust positive invariance and ultimate boundedness of nonlinear systems

In this article the problem of characterizing sets, described by vector nonlinear inequalities of the form v(x) = w, as robustly positively invariant and targets of uniformly ultimate bounded nonlinear systems is investigated. The class of general parameter uncertain continuous-time dynamical systems affected by exogenous disturbances is considered. The approach is based on establishing an associated monotone nonlinear comparison system. A numerical example is presented to illustrate the approach

Systemic α-synuclein injection triggers selective neuronal pathology as seen in patients with Parkinson’s disease

Abstract: Parkinson’s disease (PD) is an α-synucleinopathy characterized by the progressive loss of specific neuronal populations. Here, we develop a novel approach to transvascularly deliver proteins of complex quaternary structures, including α-synuclein preformed fibrils (pff). We show that a single systemic administration of α-synuclein pff triggers pathological transformation of endogenous α-synuclein in non-transgenic rats, which leads to neurodegeneration in discrete brain regions. Specifically, pff-exposed animals displayed a progressive deterioration in gastrointestinal and olfactory functions, which corresponded with the presence of cellular pathology in the central and enteric nervous systems. The α-synuclein pathology generated was both time dependent and region specific. Interestingly, the most significant neuropathological changes were observed in those brain regions affected in the early stages of PD. Our data therefore demonstrate for the first time that a single, transvascular administration of α-synuclein pff can lead to selective regional neuropathology resembling the premotor stage of idiopathic PD. Furthermore, this novel delivery approach could also be used to deliver a range of other pathogenic, as well as therapeutic, protein cargos transvascularly to the brain

Robust positive invariance and ultimate boundedness of nonlinear systems

In this article the problem of characterizing sets, described by vector nonlinear inequalities of the form v(x) = w, as robustly positively invariant and targets of uniformly ultimate bounded nonlinear systems is investigated. The class of general parameter uncertain continuous-time dynamical systems affected by exogenous disturbances is considered. The approach is based on establishing an associated monotone nonlinear comparison system. A numerical example is presented to illustrate the approach

Ultimate boundedness and robust stabilization of bilinear discrete-time systems

In this paper nonlinear time-varying and bilinear discrete-time systems with additive bounded disturbances are considered. First, conditions guaranteeing uniform ultimate boundedness for time-varying nonlinear systems are established. Then, algebraic conditions ensuring the existence of polyhedral Lyapunov functions, uniform boundedness and positive invariance for closed-loop bilinear systems are obtained. Finally, these results are applied to various robust stabilization problems for bilinear systems subject to persistent additive disturbances. It is shown that these problems can be reduced to a single or a series of linear programming problems

Vanadium in particles and sediments of the northern Saronikos Gulf, Greece

This study provides data for total and non-residual vanadium distributions in the northern Saronikos Gulf and shows that close to the Athens sewage outfall (ASO), the combined domestic and industrial wastes have resulted in a considerable increase in concentrations of vanadium in sediments and suspended solids. This appears to be the main vanadium source in the area; a second major source is a fertilizer plant (FP) near the entrance of Piraeus Harbour (PH), the impact of which is also important. Atmospheric inputs from the Piraeus industrial site and frequent crude oil spillages from ships and land-based sources seem to contribute significantly to the observed vanadium distribution, which is clearly affected by the prevailing circulation of surface waters and winds. The high percentage of the 0.5NHCl-leachable vanadium fraction in the most polluted sediments, together with positive correlation with organic carbon and certain other trace metals (i.e. Ag, Co, Cr, Fe, Zn) and negative correlation coefficients with Al and Sc, indicate that a considerable portion of the vanadium is of "anthropogenic" origin not related to lithogenous particles. It enters the system in association with relatively large organic aggregates, either authigenic or derived from sewage. © 1989

Vanadium in particles and sediments of the northern Saronikos Gulf, Greece

This study provides data for total and non-residual vanadium distributions in the northern Saronikos Gulf and shows that close to the Athens sewage outfall (ASO), the combined domestic and industrial wastes have resulted in a considerable increase in concentrations of vanadium in sediments and suspended solids. This appears to be the main vanadium source in the area; a second major source is a fertilizer plant (FP) near the entrance of Piraeus Harbour (PH), the impact of which is also important. Atmospheric inputs from the Piraeus industrial site and frequent crude oil spillages from ships and land-based sources seem to contribute significantly to the observed vanadium distribution, which is clearly affected by the prevailing circulation of surface waters and winds. The high percentage of the 0.5NHCl-leachable vanadium fraction in the most polluted sediments, together with positive correlation with organic carbon and certain other trace metals (i.e. Ag, Co, Cr, Fe, Zn) and negative correlation coefficients with Al and Sc, indicate that a considerable portion of the vanadium is of "anthropogenic" origin not related to lithogenous particles. It enters the system in association with relatively large organic aggregates, either authigenic or derived from sewage. © 1989

Neutron activation and X-ray analysis of "Thapsos Class" vases. An attempt to identify their origin

Instrumental neutron activation analysis and X-ray techniques have been applied for the determination of 24 major, minor and trace elements (Al, Ca, Cc, Co, Cr, Cs, Eu, Hf, Fe, K, La, Lu, Na, Rb, Sb, Sc, Si, Sm, Ta, Tb, Th, Ti, Yb and Zn) in three or four different groups of vases (Protocorinthian, Thapsos Class, Late Geometric Corinthian and Aigion Crater). A close agreement for all elements examined between the pottery specimens of all groups was found. The matching in chemical composition of the four groups of vases strongly suggests the same origin for all of them. © 1980 Academic Press Inc. (London) Ltd

Design, synthesis and anti-HBV activity evaluation of new substituted imidazo[4,5-b]pyridines

The design and synthesis of a number of new imidazo[4,5-b]pyridines is described. The heterocyclic scaffold possesses 6-chloro- or 5,6-dichloro-substitution and bears various 2-alkylamino-methyl or ethyl groups. The corresponding N1 and N3-tosylates are also presented. The anti-HBV activity of the compounds was evaluated in HBV infectious system at the level of HBV rcDNA secretion and CC50, EC50 and selectivity index values were determined. The tosylates showed low antiviral potency and relatively high cytotoxicity, on the contrary, a number of 2,5 and/or-6-substituted imidazopyridines, mainly those belonging to the 6-chloroimidazo[4,5-b]pyridine series, were endowed with a very interesting profile and were further investigated. The most promising among them, along with the reduction of the secreted HBV rcDNA, also caused a reduction in HBV cccDNA and pgRNA levels, with a concomitant accumulation of the intracellular encapsidated rcDNA. Surprisingly, the most active 2-diethylaminoethyl-substituted derivative (21d), was highly competitive to interferon. © 2020 Elsevier Inc