The paper studies the construction of the Hamiltonian for circuits built from the (α,β) elements of Chua's periodic table. It starts from the Lagrange function, whose existence is limited to Σ-circuits, i.e., circuits built exclusively from elements located on a common Σ-diagonal of the table. We show that the Hamiltonian can also be constructed via the generalized Tellegen's theorem. According to the ideas of predictive modeling, the resulting Hamiltonian is made up exclusively of the constitutive relations of the elements in the circuit. Within the frame of Ostrogradsky's formalism, the simulation scheme of Σ-circuits is designed and examined with the example of a nonlinear Pais-Uhlenbeck oscillator.

• Klíčová slova
• Chua’s table, Euler-Lagrange equation, Hamiltonian, Lagrangian, constitutive relation, higher-order element, memristor,
• Publikační typ
• časopisecké články MeSH

This paper discusses ergodic properties and circular statistical characteristics in neuronal spike trains. Ergodicity means that the average taken over a long time period and over smaller population should equal the average in less time and larger population. The objectives are to show simple examples of design and validation of a neuronal model, where the ergodicity assumption helps find correspondence between variables and parameters. The methods used are analytical and numerical computations, numerical models of phenomenological spiking neurons and neuronal circuits. Results obtained using these methods are the following. They are: a formula to calculate vector strength of neural spike timing dependent on the spike train parameters, description of parameters of spike train variability and model of output spiking density based on assumption of the computation realized by sound localization neural circuit. Theoretical results are illustrated by references to experimental data. Examples of neurons where spike trains have and do not have the ergodic property are then discussed.

• Klíčová slova
• Auditory pathway, Circular statistics, Ergodic theory, Ergodicity, Interspike interval, Probability distribution function, Sensory modality, Spike timing jitter, Vector strength,
• MeSH
• akční potenciály fyziologie   MeSH
• časové faktory MeSH
• lidé MeSH
• modely neurologické * MeSH
• nervová síť fyziologie   MeSH
• neurony fyziologie   MeSH
• počítačová simulace MeSH
• pravděpodobnost * MeSH
• sluch fyziologie   MeSH
• sluchová dráha fyziologie   MeSH
• sluchová percepce fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Background: The pathogenesis of adolescent idiopathic scoliosis (AIS), including the role of brain and spinal inhibitory circuits, is still poorly elucidated. The aim of this study was to identify which central inhibitory mechanisms are involved in the pathogenesis of AIS.Design: A prospective neurophysiological study, using a battery of neurophysiological tests, such as cutaneous (CuSP) and cortical (CoSP) silent periods, motor evoked potentials (MEP) and paired-pulse transcranial magnetic stimulation (ppTMS).Settings: Neurophysiological laboratory.Participants: Sixteen patients with AIS (14 females, median age 14.4) and healthy controls.Outcome measures: MEPs were obtained after transcranial magnetic stimulation (TMS) and recorded from the abductor pollicis muscle (APB). ppTMS was obtained at interval ratios (ISI) of 1, 2, 3, 6, 10, 15 and 20 ms. The cortical silent period (CoSP) was recorded from the APB. The cutaneous silent period (CuSP) was measured after painful stimuli delivered to the thumb while the subjects maintained voluntary contraction of the intrinsic hand muscles. The data were analyzed and compared with those from healthy subjects.Results: The CoSP duration was significantly prolonged in AIS patients. A significantly higher amplitude of ppTMS for ISI was found in all AIS patients, without remarkable left-right side differences. No significant difference in MEP latency or amplitude nor in the CuSP duration was obtained.Conclusion: Our observation demonstrates evidence of central nervous system involvement in adolescent idiopathic scoliosis (AIS). Lower intracortical inhibition, higher motor cortex excitability, and preserved spinal inhibitory circuits are the main findings of this study. A possible explanation of these changes could be attributed to impaired sensorimotor integration predominantly at the cortical level.

• Klíčová slova
• Adolescent idiopathic scoliosis, Cortical silent period, Cutaneous silent period, Inhibitory circuit, Paired-pulse transcranial magnetic stimulation,
• MeSH
• elektrická stimulace MeSH
• elektromyografie MeSH
• kosterní svaly fyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• motorické evokované potenciály fyziologie   MeSH
• motorické korové centrum * fyziologie   MeSH
• poranění míchy * MeSH
• prospektivní studie MeSH
• skolióza * MeSH
• transkraniální magnetická stimulace MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The maintenance of plasma sodium concentration within a narrow limit is crucial to life. When it differs from normal physiological patterns, several mechanisms are activated in order to restore body fluid homeostasis. Such mechanisms may be vegetative and/or behavioral, and several regions of the central nervous system (CNS) are involved in their triggering. Some of these are responsible for sensory pathways that perceive a disturbance of the body fluid homeostasis and transmit information to other regions. These regions, in turn, initiate adequate adjustments in order to restore homeostasis. The main cardiovascular and autonomic responses to a change in plasma sodium concentration are: i) changes in arterial blood pressure and heart rate; ii) changes in sympathetic activity to the renal system in order to ensure adequate renal sodium excretion/absorption, and iii) the secretion of compounds involved in sodium ion homeostasis (ANP, Ang-II, and ADH, for example). Due to their cardiovascular effects, hypertonic saline solutions have been used to promote resuscitation in hemorrhagic patients, thereby increasing survival rates following trauma. In the present review, we expose and discuss the role of several CNS regions involved in body fluid homeostasis and the effects of acute and chronic hyperosmotic challenges.

• MeSH
• centrální nervový systém účinky léků   fyziologie   MeSH
• hemoragický šok farmakoterapie   patofyziologie   MeSH
• homeostáza účinky léků   fyziologie   MeSH
• hypertonický solný roztok aplikace a dávkování   MeSH
• krevní tlak účinky léků   fyziologie   MeSH
• ledviny účinky léků   fyziologie   MeSH
• lidé MeSH
• nervová síť fyziologie   MeSH
• osmóza účinky léků   fyziologie   MeSH
• srdeční frekvence účinky léků   fyziologie   MeSH
• tělesné tekutiny účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• hypertonický solný roztok MeSH

OBJECTIVE: The cutaneous silent period (SP) is a spinal inhibitory reflex, which suppresses activity in spinal motor nuclei. Transcranial magnetic stimulation (TMS) elicits a cortical SP, which represents GABA(B) receptor-mediated inhibition of cortical excitability. Baclofen as a strong GABA(B) agonist effectively reduces muscle hypertonia, however, it is not known whether intrathecal baclofen (ITB) may modulate spinal inhibitory circuits. METHODS: We evaluated clinical and neurophysiological effects of ITB in ten patients with severe spasticity due to spinal cord injury (n = 9) and chronic progressive multiple sclerosis (n = 1). Neurophysiological assessment included H reflex and cutaneous and cortical SPs, before and 15, 30, 60, 90, 120, and 180 min after ITB bolus administration. RESULTS: ITB suppressed soleus H reflex as early as 15 min after lumbar bolus injection; MAS scores declined after 1 h. Cortical SP end latency and duration increased progressively with a significant maximum 3h following ITB bolus, whereas cutaneous SP latency and duration did not change significantly. CONCLUSION: The present findings suggest that baclofen does not affect the cutaneous SP, but prolongs the cortical SP. SIGNIFICANCE: The spinal inhibitory circuitry of the cutaneous SP is not modulated by GABA(B) receptor-mediated activity, in contrast to the cortical inhibitory circuitry of the cortical SP, which is subject to powerful GABA(B) control.

• MeSH
• agonisté receptorů GABA-B aplikace a dávkování   farmakologie   MeSH
• baklofen aplikace a dávkování   farmakologie   MeSH
• časové faktory MeSH
• dospělí MeSH
• H-reflex účinky léků   fyziologie   MeSH
• kosterní svaly inervace   MeSH
• lidé středního věku MeSH
• lidé MeSH
• míšní nervy účinky léků   patofyziologie   MeSH
• mozková kůra účinky léků   patofyziologie   MeSH
• poranění páteře komplikace   MeSH
• reakční čas účinky léků   fyziologie   MeSH
• reflex účinky léků   fyziologie   MeSH
• roztroušená skleróza komplikace   MeSH
• spinální injekce MeSH
• svalová spasticita etiologie   patofyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• agonisté receptorů GABA-B MeSH
• baklofen MeSH

Aromaticity is a fundamental concept in chemistry. It is described by Hückel's rule that states that a cyclic planar π-system is aromatic when it shares 4n+2 π-electrons and antiaromatic when it possesses 4n π-electrons. Antiaromatic compounds are predicted to exhibit remarkable charge transport properties and high redox activities. However, it has so far only been possible to measure compounds with reduced aromaticity but not antiaromatic species due to their energetic instability. Here, we address these issues by investigating the single-molecule charge transport properties of a genuinely antiaromatic compound, showing that antiaromaticity results in an order of magnitude increase in conductance compared with the aromatic counterpart. Single-molecule current-voltage measurements and ab initio transport calculations reveal that this results from a reduced energy gap and a frontier molecular resonance closer to the Fermi level in the antiaromatic species. The conductance of the antiaromatic complex is further modulated electrochemically, demonstrating its potential as a high-conductance transistor.

• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Both nonvirulent (15 strains) and virulent (1 strain) variants of Naegleria fowleri were isolated from the cooling circuits in seven of ten examined plants in North Moravia. No amoebae were found in waters with a high salinity (electric conductivity more than 614 microseconds) and with a low content of phosphates (less than 0.37 mg . 1(-1)) and oxygen (less than 7.4 mg . 1(-1)). Other results of the physical, chemical and bacteriological examinations showed no direct bearing on the occurrence of N. fowleri.

• MeSH
• Amoeba izolace a purifikace   MeSH
• elektrárny * MeSH
• mikrobiologie vody * MeSH
• průmysl * MeSH
• Publikační typ
• časopisecké články MeSH

Antiaromatic molecules have been predicted to exhibit increased electron transport properties when placed between two nanoelectrodes compared to their aromatic analogues. While some studies have demonstrated this relationship, others have found no substantial increase. We use atomistic simulations to establish a general relationship between the electronic spectra of aromatic, antiaromatic, and quinoidal molecules and illustrate its implications for electron transport. We compare the electronic properties of a series of aromatic-antiaromatic counterparts and show that antiaromaticity effectively p-dopes the aromatic electronic spectra. As a consequence, the conducting properties of aromatic-antiaromatic analogues are closely related. For similar attachment points to the electrodes, an interference feature is expected in the HOMO-LUMO gap of one whenever it is absent in the other one. We demonstrate how the relative conductance of aromatic-antiaromatic pairs can be tuned and even reversed through the choice of chemical linker groups. Our work provides a general picture relating connectivity, (anti)aromaticity, and quantum interference and establishes new design rules for single molecule circuits.

• Klíčová slova
• aromaticity, density functional calculations, electron transport, electronic structure, molecular electronics,
• Publikační typ
• časopisecké články MeSH

We studied cognitive functions related to processing sensory and motor activities in the basal ganglia (BG), specifically in the putamen and in cortical structures forming the BG-frontocortical circuits. Intracerebral recordings were made from 160 brain sites in 32 epilepsy surgery candidates. We studied P3-like potentials in five different tests evoked by auditory and visual stimuli, and two sustained potentials that are related to cognitive activities linked with movement preparation: BP (Bereitschaftspotential) and CNV (contingent negative variation). We compared the presence of a potential with a phase reversal or an amplitude gradient to the absence of a generator. All of the studied cognitive potentials were generated in the BG; the occurrence in frontal cortical areas was more selective. The frequency of all but one potential was significantly higher in the BG than in the prefrontal and in the cingulate cortices. The P3-like potentials elicited in the oddball paradigm were also more frequent in the BG than in the motor/premotor cortex, while the occurrence of potentials elicited in motor tasks (BP, CNV, and P3-like potentials in the CNV paradigm) in the motor cortex did not significantly differ from the occurrence in the BG. The processing of motor tasks fits with the model by Alexander et al. of segregated information processing in the motor loop. A variable and task-dependent internal organisation is more probable in cognitive sensory information processing. Cognitive potentials were recorded from all over the putamen. The BG may play an integrative role in cognitive information processing.

• MeSH
• akustická stimulace MeSH
• bazální ganglia fyziologie   MeSH
• čelní lalok fyziologie   MeSH
• cingulární gyrus fyziologie   MeSH
• dospělí MeSH
• evokované potenciály fyziologie   MeSH
• kognice fyziologie   MeSH
• kontingentní negativní variace fyziologie   MeSH
• lidé MeSH
• mapování mozku MeSH
• mladiství MeSH
• motorické korové centrum fyziologie   MeSH
• nervové dráhy fyziologie   MeSH
• pohyb fyziologie   MeSH
• prefrontální mozková kůra fyziologie   MeSH
• putamen fyziologie   MeSH
• reakční čas fyziologie   MeSH
• sluchová percepce fyziologie   MeSH
• sluchové evokované potenciály fyziologie   MeSH
• zraková percepce fyziologie   MeSH
• zrakové evokované potenciály fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Miniaturized energy storage devices are essential to power the growing number and variety of microelectronic technologies. Here, a concept of self-propelled microscale energy storage elements that can move, reach, and power electronic circuits is reported. Microrockets consisting of a nickel sulfide (NiS) outer layer and a Pt inner layer are prepared by template-assisted electrodeposition, and designed to store energy through NiS-mediated redox reactions and propel via the Pt-catalyzed decomposition of H2 O2 fuel. Scanning electrochemical microscopy allows visualizing and studying the energy storage ability of a single microrocket, revealing its pseudocapacitive nature. This proves the great potential of such technique in the field of micro/nanomotors. On-demand delivery of energy storage units to electronic circuits has been demonstrated by releasing microrockets on an interdigitated array electrode as an example of electronic circuit. Owing to their self-propulsion ability, they reach the active area of the electrode and, in principle, power its functions. These autonomously moving energy storage devices will be employed for next-generation electronics to store and deliver energy in previously inaccessible locations.

• Klíčová slova
• electronics, energy devices, micromotors, microrobots, supercapacitors,
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH