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Je uvedeno celé znění Norimberského kodexu, který je pokusem o formulaci všeobecných zásad výzkumu s použitím lidských subjektů. Problematika současného vědeckého zkoumání (informovaný souhlas, úmrtnost závislá na léčbě) je konfrontována s výzvou tohoto kodexu.
The Nuremberg Code, an attempt to formulate am universal standard for human experimentation, is presented. Some problems of present scientific research (informed consent, treatement-related mortality) are confronted with the calls of this code.
In this paper we investigate the rate coding capabilities of neurons whose input signal are alterations of the base state of balanced inhibitory and excitatory synaptic currents. We consider different regimes of excitation-inhibition relationship and an established conductance-based leaky integrator model with adaptive threshold and parameter sets recreating biologically relevant spiking regimes. We find that given mean post-synaptic firing rate, counter-intuitively, increased ratio of inhibition to excitation generally leads to higher signal to noise ratio (SNR). On the other hand, the inhibitory input significantly reduces the dynamic coding range of the neuron. We quantify the joint effect of SNR and dynamic coding range by computing the metabolic efficiency-the maximal amount of information per one ATP molecule expended (in bits/ATP). Moreover, by calculating the metabolic efficiency we are able to predict the shapes of the post-synaptic firing rate histograms that may be tested on experimental data. Likewise, optimal stimulus input distributions are predicted, however, we show that the optimum can essentially be reached with a broad range of input distributions. Finally, we examine which parameters of the used neuronal model are the most important for the metabolically efficient information transfer.
- MeSH
- adenosintrifosfát metabolismus MeSH
- akční potenciály fyziologie MeSH
- excitační postsynaptické potenciály fyziologie MeSH
- membránové potenciály fyziologie MeSH
- modely neurologické * MeSH
- nervové vedení fyziologie MeSH
- nervový přenos fyziologie MeSH
- nervový útlum fyziologie MeSH
- neurony fyziologie MeSH
- počítačová simulace MeSH
- poměr signál - šum MeSH
- výpočetní biologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This paper presents a rate-code model of binaural interaction inspired by recent neurophysiological findings. The model consists of a peripheral part and a binaural part. The binaural part is composed of models of the medial superior olive (MSO) and the lateral superior olive (LSO), which are parts of the auditory brainstem. The MSO and LSO model outputs are preprocessed in the interaural time difference (ITD) and interaural level difference (ILD) central stages, respectively, which give absolute values of the predicted lateralization at their outputs, allowing a direct comparison with psychophysical data. The predictions obtained with the MSO and LSO models are compared with subjective data on the lateralization of pure tones and narrowband noises, discrimination of the ITD and ILD, and discrimination of the phase warp. The lateralization and discrimination experiments show good agreement with the subjective data. In the case of the phase-warp experiment, the models agree qualitatively with the subjective data. The results demonstrate that rate-code models of MSO and LSO can be used to explain psychophysical data considering lateralization and discrimination based on binaural cues.
- MeSH
- diskriminace (psychologie) MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- lokalizace zvuku * MeSH
- modely neurologické * MeSH
- mozkový kmen fyziologie MeSH
- sluchové kmenové evokované potenciály MeSH
- ucho fyziologie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: The LUCAS (Lund University Cardiopulmonary Assist System; Physio-Control Inc./Jolife AB, Lund, Sweden) was developed for automatic chest compressions during cardiopulmonary resuscitation (CPR). Evidence on the use of this device in out-of-hospital cardiac arrest (OHCA) suggests that it should not be used routinely because it has no superior effects. OBJECTIVE: The aim of this study was to compare the effect of CPR for OHCA with and without LUCAS via a regional nonurban emergency medical service (EMS) physician-present prehospital medical system. METHODS: We analyzed a prospective registry of all consecutive OHCA patients in four EMS stations. Two of them used a LUCAS device in all CPR, and the EMS crews in the other two stations used manual CPR. Individuals with contraindication to LUCAS or with EMS-witnessed arrest were excluded. RESULTS: Data from 278 patients were included in the analysis, 144 with LUCAS and 134 with manual CPR. There were more witnessed arrests in the LUCAS group (79.17% vs. 64.18%; p = 0.0074) and patients in the LUCAS group were older (p = 0.03). We found no significant difference in return of spontaneous circulation (30.6% in non-LUCAS vs. 25% in LUCAS; p = 0.35). In the LUCAS group, we observed significantly more conversions from nonshockable to shockable rhythm (20.7% vs. 10.10%; p = 0.04). The 30-day survival rate was significantly lower in the LUCAS group (5.07% vs. 16.31% in the non-LUCAS group; p = 0.044). At 180-day follow-up, we observed no significant difference (5.45% in non-LUCAS vs. 9.42% in LUCAS; p = 0.25). CONCLUSIONS: Use of the LUCAS system decreased survival rate in OHCA patients. Significantly higher 30-day mortality was seen in LUCAS-treated patients.
- MeSH
- hrudník MeSH
- kardiopulmonální resuscitace * MeSH
- lidé MeSH
- míra přežití MeSH
- urgentní zdravotnické služby * MeSH
- zástava srdce mimo nemocnici * terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Článek popisuje hardware a software mikropočítačového systému určeného pro měření a vyhodnocování variability srdeční frekvence v medicínské praxi. System se skládá z nastavitelného hradního pásu s elektrodami, z vysilače a přijímače kódovaného radiového Signálu. Přijímač je připojen k osobnímu počítači IBM PC prostřednictvím standardního sériového portu (COMl nebo COM2). Součástí systému je softwarové vybavení pro vyhodnocení stavu autonomního nervového systému během speciálních testů jako Ewingova baterie kardiovaskulárních testů a tzv. „Short time" spektrální analýza variability srdeční frekvence. Popisovaný systém může být použit jak v běžné medicinské praxi, tak pro výzkumné účely především v kardiológii, diabetológii, neurologii a sportovním lékařství.
Hardware and software of a microcomputer system for measurement and evaluation of heart rate variability in medical practice is presented. The system involves an adjustable thorax belt with electrodes, a transmitter and a receiver of coded radio signals. The receiver is connected to a standard serial port (COMl or COM2) of IBM PC compatible personal computer. The system is completed by software programs allowing the determination of the autonomic nervous system state during special examinations, it means so-called Ewing's batery of cardiovascular tests and „Short Time" spectral analysis of heart rate variability. The described system -an be used both in daily medical practice and under conditions of experimental work. It can be applied especially in cardiology, diabetology, neurology and sport medicine.
The apparent stochastic nature of neuronal activity significantly affects the reliability of neuronal coding. To quantify the encountered fluctuations, both in neural data and simulations, the notions of variability and randomness of inter-spike intervals have been proposed and studied. In this article we focus on the concept of the instantaneous firing rate, which is also based on the spike timing. We use several classical statistical models of neuronal activity and we study the corresponding probability distributions of the instantaneous firing rate. To characterize the firing rate variability and randomness under different spiking regimes, we use different indices of statistical dispersion. We find that the relationship between the variability of interspike intervals and the instantaneous firing rate is not straightforward in general. Counter-intuitively, an increase in the randomness (based on entropy) of spike times may either decrease or increase the randomness of instantaneous firing rate, in dependence on the neuronal firing model. Finally, we apply our methods to experimental data, establishing that instantaneous rate analysis can indeed provide additional information about the spiking activity.
- Publikační typ
- časopisecké články MeSH
Statistika úmrtnosti patří mezi základní zdravotnické ukazatele, a proto je často analyzována. Autoři se domnívají, že je metodicky vhodné shrnout obtíže, se kterými je možné se setkat, i statistické postupy, které je nutné použít, aby prováděná porovnání i analyzované časové trendy maximálně odpovídaly skutečnému vývoji zdravotního stavu populace. Diskutují metodiku Mezinárodní klasifikace nemocí a dále popisují postup přímé standardizace dat včetně stanovení variability standardizovanéhoúdaje.Naproblematiceonemocněnídýchacíchcestpakdokládají,jakáúskalípro praxi přinášejí revize kódového systému Mezinárodní klasifikace nemocí, a ilustrují numericky popisované postupy.
The death rate statistics belongs to the essential health parameters and it is therefore frequently analysed. Authors suggest reviewing problems, which could be met, and discussing statistical methods in order to make the comparison and analysis of the development as much corresponding to the actual health state of the population as possible. Authors also discuss methods of the „International classification of diseases“ and describe methods of direct data standardisation, including estimation of the variability. Using respiratory diseases as an example, authors illustrate the problems of revision of the code system in the „International classification of diseases“ and the give examples of numerical evaluation.
- MeSH
- dítě MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mortalita MeSH
- nemoc etnologie MeSH
- nemoci dýchací soustavy diagnóza klasifikace MeSH
- referenční standardy MeSH
- statistika jako téma MeSH
- Check Tag
- dítě MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- přehledy MeSH
- Geografické názvy
- Česká republika MeSH
Recent studies on the theoretical performance of latency and rate code in single neurons have revealed that the ultimate accuracy is affected in a nontrivial way by aspects such as the level of spontaneous activity of presynaptic neurons, amount of neuronal noise or the duration of the time window used to determine the firing rate. This study explores how the optimal decoding performance and the corresponding conditions change when the energy expenditure of a neuron in order to spike and maintain the resting membrane potential is accounted for. It is shown that a nonzero amount of spontaneous activity remains essential for both the latency and the rate coding. Moreover, the optimal level of spontaneous activity does not change so much with respect to the intensity of the applied stimulus. Furthermore, the efficiency of the temporal and the rate code converge to an identical finite value if the neuronal activity is observed for an unlimited period of time.
- MeSH
- časové faktory MeSH
- energetický metabolismus * MeSH
- lidé MeSH
- membránové potenciály MeSH
- modely neurologické * MeSH
- nervová síť cytologie fyziologie MeSH
- neuronové sítě * MeSH
- neurony fyziologie MeSH
- počítačová simulace MeSH
- výpočetní biologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
