Verifying Weak and Strong kk-Step Opacity in Discrete-Event Systems

Opacity is an important system-theoretic property expressing whether a system may reveal its secret to a passive observer (an intruder) who knows the structure of the system but has only limited observations of its behavior. Several notions of opacity have been discussed in the literature, including current-state opacity, $k$-step opacity, and infinite-step opacity. We investigate weak and strong $k$-step opacity, notions that generalize both current-state opacity and infinite-step opacity, and ask whether the intruder is not able to decide, at any instant, when respectively whether the system was in a secret state during the last $k$ observable steps. We design a new algorithm verifying weak $k$-step opacity, the complexity of which is lower than the complexity of existing algorithms and does not depend on the parameter $k$, and show how to use it to verify strong $k$-step opacity by reducing strong $k$-step opacity to weak $k$-step opacity. The complexity of the resulting algorithm is again better than the complexity of existing algorithms and does not depend on the parameter $k$

Two power-decreasing derivation restrictions in generalized scattered context grammars

The present paper introduces and discusses generalized scattered context grammars that are based upon sequences of productions whose left-hand sides are formed by nonterminal strings, not just single nonterminals. It places two restrictions on the derivations in these grammars. More specifically, let k be a positive integer. The first restriction requires that all rewritten symbols occur within the first k symbols of the first continuous block of nonterminals in the sentential form during every derivation step. The other restriction defines derivations over sentential forms containing no more than k occurrences of nonterminals. As its main result, the paper demonstrates that both restrictions decrease the generative power of these grammars to the power of context-free grammars

Leftmost derivations of propagating scattered context grammars: a new proof

Automata, Logic and Semantic

THE DYNAMICS OF HAEMOSTATIC PARAMETERS IN ACUTE PSYCHOTIC PATIENTS: A ONE-YEAR PROSPECTIVE STUDY

Background: The primary goal of the present study was to replicate our previous finding of increased coagulation and thrombocytes activity in drug-naïve psychotic patients in comparison with healthy controls and ascertain whether the blood levels of thrombogenesis markers further increase over the course of a consecutive one-year antipsychotic treatment. Subjects and methods: We investigated the plasma levels of markers indicating activation of coagulation (D-dimers and Factor VIII) and platelets (soluble P-selectin, sP-selectin) in an antipsychotic-naive group of nineteen men and seventeen women with acute psychosis (age 28.1±8.0 years, body mass index 22.6±4.2), and thirty-seven healthy volunteers matched for age, gender and body mass index. In the patient group, we repeated these assessments after three months and again after one year of antipsychotic treatment. Results: D-dimers (median 0.38 versus 0.19 mg/l; p=0.00008), factor VIII (median 141.5% versus 110%; p=0.02) and sPselectin (median 183.6 versus 112.4 ng/ml; p=0.00005) plasma levels were significantly increased in the group of patients with acute psychosis prior to treatment compared with healthy volunteers. The plasma levels of sP-selectin varied significantly (p=0.016) in the course of the one-year antipsychotic treatment, mainly between 3 and 6 months after start of therapy. The plasma levels of D-dimers and factor VIII did not change significantly, D-dimers remained elevated in contrast to the healthy controls. Conclusions: Patients with acute psychosis had increased levels of markers of thrombogenesis in comparison to the healthy volunteers. The haemostatic parameters also remained elevated during the one-year antipsychotic treatment

Electronic Control Board for Phased Antenna Array Research and Prototyping

Czech Science Foundation under the project number 20-02046S (Antenna Arrays with Quantized Controlling)Current state-of-the-art phased antenna arrays used in modern generations of mobile networks and radars in terrestrial applications or as spacecraft antennas in space applications tend to be very complex and expensive devices with many mutually coupled elements and many input/output ports that are excited with varying amplitude and phase. Also, the simulation and design of such complex antenna arrays may not be accurate due to many sources of uncertainty, such as inhomogeneity of high-frequency substrate properties over large area, manufacturing tolerances, idealized component models, etc. Therefore, simpler solutions of these antenna arrays in the form of sparse arrays, non-uniform arrays or arrays with parasitic elements are intensively studied. In this paper, we present an experimental electronic control board, which is used in our research of simplified phased array antennas. This digitally controllable board, in addition to the commonly used changes in the amplitude and phase of the propagated signal, can connect the individual antenna elements to a programmable impedance load, variable in the capacitive and inductive range. The aim of the implementation of this control electronic board is to study the influence of the mutual couplings of actively excited elements of the antenna array and parasitic elements loaded by variable impedance load on the resulting properties of the antenna array

Transformace obsahu ve třídě: vliv detailů výuky na žákovské porozumění struktuře vědecké znalosti

Cílem studie je v kontextu historického vývoje didaktiky analyticky vysvětlit teoretický konstrukt transformace obsahu včetně struktury jeho podpojmů, zdůvodnit jeho operacionalizaci pro výzkum vztahů mezi vyučováním a učením prostřednictvím sémanticko-logických sítí (S-L sítí) a demonstrovat aplikační potenciál tohoto přístupu replikací ve výuce fyziky, geografie a matematiky. Cílem výzkumu bylo popsat a vysvětlit důvody, které způsobily potíže žáků v porozumění vědeckým schématům během transformací obsahu ve třídě. Metody: Pro analýzu vztahů mezi vyučováním a učením prostřednictvím vzdělávacího obsahu byla použita modifikovaná metodika 3A rozšířená o kognitivní vrstvu. Metodologickým východiskem analýzy je komparace S-L sítí tří základních dimenzí obsahové transformace: vědecké schéma, tematizace vědeckého obsahu ve vzdělávacím prostředí a reprezentace mentálních schémat žáků při řešení problémů. Výsledky: Teoretické konstrukty a jejich metodologická operacionalizace byly ověřeny replikací ve vzdělávacích oborech fyzika, geografie a matematika. V každém z těchto oborů umožnily vysvětlovat vliv detailů výuky na změny ve struktuře žákovské znalosti s ohledem na specifický obsah daného oboru. Závěry: Prokázalo se, že i detailní momenty S-L struktury, v praxi obtížně zachytitelné, mohou mít silný vliv na žákovské porozumění struktuře vědecké znalosti. Přitom byly úspěšně replikovány teoretické a metodologické konstrukty. Získané poznatky mohou sloužit k bezprostřední podpoře vzdělávací praxe v příslušných oblastech učiva