Performance comparison of Yb:YAG ceramics and crystal gain material in a large-area, high-energy, high average-power diode-pumped laser.

We compare for the first time the influence of different Yb:YAG gain media on the performance of a large-area, high average-power laser system with an output energy of up to 6 J. Monocrystalline slabs grown by a new technique without central growth defect are compared with ceramics. Small signal gain, maximum output energy and thermal lensing are compared for ceramic slabs with co-sintered amplified spontaneous emission (ASE) absorber cladding, monocrystalline slab with and without optically bonded ASE absorber cladding, and surface structured monocrystalline slabs. We show that these large monocrystals with optically bonded absorber cladding have similar performance to cladded ceramics, so far the only material for high-energy Yb:YAG lasers.

Locally advanced colorectal cancer in pregnancy.

OBJECTIVE: To highlight the issue of diagnostics and treatment management in colorectal cancer of pregnant women. DESIGN: Case report. SETTING: Department of Obstetrics and Gynaecology, Pardubice Hospital. CASE REPORT: We present a case of a 24-year-old secundigravida, diagnosed as colorectal cancer in week 34 of pregnancy, manifesting as a diarrhoea and a stomach ache. The diagnosis was made in an advanced stage due to underestimation of clinical symptoms. CONCLUSION: The diagnosis of the colorectal cancer in pregnancy can be difficult because the presenting symptoms are easily attributable to pregnancy. Therefore the advanced disease is diagnosed more frequently in pregnant patients than in the general population. Colorectal cancer should be managed by multidisciplinary team with regard to gestation.

Organic and mineral fertilization, respectively, increase and decrease the development of external mycelium of arbuscular mycorrhizal fungi in a long-term field experiment.

Effects of long-term mineral fertilization and manuring on the biomass of arbuscular mycorrhizal fungi (AMF) were studied in a field experiment. Mineral fertilization reduced the growth of AMF, as estimated using both measurements of hyphal length and the signature fatty acid 16:1omega5, whereas manuring alone increased the growth of AMF. The results of AMF root colonization followed the same pattern as AMF hyphal length in soil samples, but not AMF spore densities, which increased with increasing mineral and organic fertilization. AMF spore counts and concentration of 16:1omega5 in soil did not correlate positively, suggesting that a significant portion of spores found in soil samples was dead. AMF hyphal length was not correlated with whole cell fatty acid (WCFA) 18:2omega6,9 levels, a biomarker of saprotrophic fungi, indicating that visual measurements of the AMF mycelium were not distorted by erroneous involvement of hyphae of saprotrophs. Our observations indicate that the measurement of WCFAs in soil is a useful research tool for providing information in the characterization of soil microflora.

Long-term fertilization affects the abundance of saprotrophic microfungi degrading resistant forms of soil organic matter.

The effect of mineral and organic fertilization on the occurrence of soil microorganisms was determined in a field experiment. The colony-forming unit counts of saprotrophic microfungi, when estimated on a silicate gel medium containing fulvic acid as a sole carbon source, increased significantly with increasing doses of mineral and organic fertilization. Partial correlation analysis indicated that, unlike bacteria and actinomycetes, microfungi utilizing fulvic acid were significantly associated with soil organic carbon. No significant effects on bacteria and microfungi counted on common microbiological media were observed but counts of actinomycetes increased in a manured soil extensively fertilized by a mineral fertilizer. Fulvic acid utilizing microfungi, which are associated with areas rich in organics, play possibly the main role in mineralization of resistant forms of soil organic matter.

Neurotoxicity profile of supermethrin, a new pyrethroid insecticide.

The use of a standard two-tier neurotoxicity screening procedure in the context of risk assessment is exemplified. Testing of a new pyrethroid in rats addressed the following sequence of questions: Does the substance evoke neurotoxic symptoms in sublethal doses? Do these symptoms reflect a primary neurotropic action? What are the dynamic characteristics of injury, the clinical profile of effect, and the relative potency of the tested substance compared to similar compounds? - The testing protocol is an animal analogue of a systematic neurological and psychological examination in man. First tier tests (structured observation, motor activity measurement, simple neurological examination) were applied after the first dose, during repeated dosing phase and in the restitution phase. Facultative tests for the second-tier examination (motor activity pattern, learning/retention test, evoked potentials, dynamic motor performance) were selected on the basis of effects revealed by the first-tier testing. Supermethrin evoked acute neurotoxicity in sublethal doses, ranging from 1/30 to 1/15 of LD50. The clinical pattern was similar to other cyano-substituted pyrethroids. Behavioural inhibition was transient and complete tolerance to it developed after 4-week repeated dosing. No indications of long-lasting changes in neuronal excitability or in learning and memory processes were found. Ataxia and excitomotoric phenomena dominated both the acute and the subchronic picture. Marked and persistent motor disturbances, including symptoms of lower motoneuron injury, were limited to individual animals of the highest, near-lethal dose group (27 mg-kg-1). Compared to lambda-cyhalothrin, the effects of supermethrin were 2 to 3 times weaker, disappeared more rapidly, cumulated less, and had higher tendency to tolerance.

A comparison of methods for estimating spectral power densities of EEG signals.

The paper suggests an objective method for the choice of a suitable estimate of the spectral power density in the context of the analysis of biosignals. The method is based on the principle evaluating the degree of prewhitening (i.e. elimination of autocorrelation): this prewhitening is achieved just by means of filters exploiting the compared spectral estimates. The method is demonstrated by a practical example estimating the spectral power density of EEG signals.

Detection and interpolation of outliers in biosignals.

Detection of outliers in recorded biosignals and their interpolation is described. The detection of outliers is based on the simple rule of 3 sigma. The subsequent interpolation is performed according to the method proposed by Brubacher and Wilson for autoregressive processes. The output of the suggested procedure can be treated by standard programs of statistical analysis as long as the influence of outliers is eliminated. The program in Fortran IV developed in the Institute of Hygiene and Epidemiology, Prague, performs automatically the detection of outliers in an input signal and their replacement by means of the proposed interpolation method.

[Long-term survival after palliative embolization of kidneys affected by tumors]. / Dlouhodobé prezívání po paliativní embolizaci ledviny postizené nádorem.

Based on their own experience and data in the literature, the authors recommend to use also in future palliative embolization of the kidney as part of comprehensive treatment of patients with inoperable tumours of the kidney. They describe their experience with a group of 20 patients. In one female patient after palliative embolization an unusually favourable effect was observed with macroscopic disappearance of the tumour and affection of the pleura, associated with prolonged survival.

EEG as a neurotoxicological indicator.

In living organisms both chemical agents and physical factors [16] may produce neurophysiological change that affects EEG activity. EEG signals are very suitable for non-invasive measurement of CNS reactions, but quite complicated equipment is necessary for measurement and analysis. We have implemented a system that permits the study of EEG changes both in time and frequency domains using broad-band analysis or fast Fourier transformation (FFT). Experimental animals were influenced by high doses of toxic agents (CO, CS2, barbiturates, pesticides), drugs and both non-ionizing and ionizing radiation. The EEG changes reflecting the influencing factor, respectively its quantity may be divided into several classes: (1) appearance of new activities; (2) disappearance of some activities; (3) increase of amplitudes, respectively spectral power densities (SPD) in certain frequencies; and (4) decrease of amplitudes, respectively SPD in certain frequencies. All changes are related to the controls, i.e. to the relatively normal state of CNS. Furthermore it is possible to investigate the temporal dynamics of these changes. Physiological concordance of these findings is sometimes possible from clinical analogues, but in other cases is unknown and considerable effort will be necessary to elucidate these correlates. Anyhow in some toxic substances, the EEG may be quite insensitive as an indicator of neurotoxicity. The best way to solve these problems is to collect sufficient experimental data for complex analysis. Although few relevant data are currently available, temporal and frequency domain measures of EEG activity appear to have promise as neurotoxicity indicators.

Analysis of the time series of the EEG frequency spectra and of EEG spectral power densities.

Some examples of the use of the principal component model for the economic description of the structure of the multiple time series and for the data reduction in the quantitative EEG studies are presented. The broad-band EEG frequency spectra were measured with the use of an electronic system designed by J. Dvorák. The EEG spectral power densities were computed via the discrete Fourier Transform (namely FFT) algorithm. The estimated two or three first principal components account for the major part of the total variance of individual EEG variables: The results hold for the used elementary epoch of measurement, i.e. 5 sec. - With the use of the algorithms and FORTRAN IV programs developed by J. Andel, T. Cipra and L. Tomásek a data reduction by a factor of 1:2000 can be achieved without any substantial loss of biological information. - The described methods help to obtain a better insight into the structure of the data and represent a powerful tool for data reduction at least in a certain class of experimental EEG studies (experimental toxicology, pharmacology, experimental neurology).

Influence of fluctuating temperature on soil microflora.

The effect of different constant and "square-wave" fluctuating temperatures on the soil microflora was studied in laboratory experiments. The growth of soil microorganisms was higher at lower temperatures, indicating the higher degree of substrate immobilization and the better energy economy of the soil bionta. Microbial counts were slightly higher after five days of incubation at fluctuating temperatures than those obtained at a constant mean temperature. It was important whether the fluctuation started at lower or at higher temperatures. At a fluctuating temperature the amount of nitrates decreased compared to the amount at a constant temperature. The development dynamics of soil microorganisms was accelerated by the fluctuation of temperature as judged by nitrogen transformation and simultaneous changes in microbial counts.

Spreading EEG depression elicited by controlled deformation of the rat cerebral cortex.

The elicitation of cortical spreading depression (SD) by electronically generated mechanical stimuli was studied in 52 pentobarbital-anaesthetized rats. The stimuli were applied with a rod (target area 7.065 mm2) immersed at a constant velocity (3 X 10(-6) to 2 X 10(-1) m/sec) to varying depths (0 to 2.5 mm) from the surface of the cerebral cortex at the level of the bregma. SD elicitation depended on the velocity as well as the amplitude of deformation. The relationship between the velocity, v (m/sec), and amplitude, A (m), of threshold stimuli for SD elicitation is described by the equation 6.4 log A + log v = -21.08 in the given measuring range. The mean threshold velocity at a depth of 0.9 mm was 2.85 X 10(-2) m/sec; at 2.2 mm it was 8.54 X 10(-5) m/sec. If the rod was immersed to a given depth at a subthreshold velocity, to elicit SD by plunging it in a further 0.5 mm it was necessary to use velocities of a higher order than the one needed to obtain the same total deformation with a single threshold pulse. In extensive deformation, this velocity difference disappeared. Comparison of the results obtained by a free fall and electronically controlled deformation showed that the threshold of the mechanical stimulus eliciting spreading EEG depression could be expressed by the deformation velocity and amplitude better than by the amount of kinetic energy absorbed.